WorldWideScience

Sample records for plant pathogenic fungus

  1. Viruses of the plant pathogenic fungus Sclerotinia sclerotiorum.

    Science.gov (United States)

    Jiang, Daohong; Fu, Yanping; Guoqing, Li; Ghabrial, Said A

    2013-01-01

    Sclerotinia sclerotiorum is a notorious plant fungal pathogen with a broad host range including many important crops, such as oilseed rape, soybean, and numerous vegetable crops. Hypovirulence-associated mycoviruses have attracted much attention because of their potential as biological control agents for combating plant fungal diseases and for use in fundamental studies on fungal pathogenicity and other properties. This chapter describes several mycoviruses that were isolated from hypovirulent strains except for strain Sunf-M, which has a normal phenotype. These viruses include the geminivirus-like mycovirus Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1), Sclerotinia debilitation-associated RNA virus (SsDRV), Sclerotinia sclerotiorum RNA virus L (SsRV-L), Sclerotinia sclerotiorum hypovirus 1 (SsHV-1), Sclerotinia sclerotiorum mitoviruses 1 and 2 (SsMV-1, SsMV-2), and Sclerotinia sclerotiorum partitivirus S (SsPV-S). Unlike many other fungi, incidences of mixed infections with two or more mycoviruses in S. sclerotiorum are particularly high and very common. The interaction between SsDRV and S. sclerotiorum is likely to be unique. The significance of these mycoviruses to fungal ecology and viral evolution and the potential for biological control of Sclerotinia diseases using mycoviruses are discussed.

  2. Endocytosis in the plant-pathogenic fungus Ustilago maydis.

    Science.gov (United States)

    Fuchs, U; Steinberg, G

    2005-10-01

    Filamentous fungi are an important group of tip-growing organisms, which include numerous plant pathogens such as Magnaporthe grisea and Ustilago maydis. Despite their ecological and economical relevance, we are just beginning to unravel the importance of endocytosis in filamentous fungi. Most evidence for endocytosis in filamentous fungi is based on the use of endocytic tracer dyes that are taken up into the cell and delivered to the vacuole. Moreover, genomewide screening for candidate genes in Neurospora crassa and U. maydis confirmed the presence of most components of the endocytic machinery, indicating that endocytosis participates in filamentous growth. Indeed, it was shown that in U. maydis early endosomes cluster at sites of growth, where they support morphogenesis and polar growth, most likely via endosome-based membrane recycling. In humans, such recycling processes to the plasma membrane involve small GTPases such as Rab4. A homologue of this protein is encoded in the genome of U. maydis but is absent from the yeast Saccharomyces cerevisiae, suggesting that Rab4-mediated recycling is important for filamentous growth. Furthermore, human Rab4 regulates traffic of early endosomes along microtubules, and a similar microtubule-based transport is described for U. maydis. These observations suggest that Rab4-like GTPases might regulate endosome- and microtubule-based recycling during tip growth of filamentous fungi.

  3. The plant nitrogen mobilization promoted by Colletotrichum lindemuthianum in Phaseolus leaves depends on fungus pathogenicity.

    Science.gov (United States)

    Tavernier, Virginie; Cadiou, Sandrine; Pageau, Karine; Laugé, Richard; Reisdorf-Cren, Michèle; Langin, Thierry; Masclaux-Daubresse, Céline

    2007-01-01

    Nitrogen plays an essential role in the nutrient relationship between plants and pathogens. Some studies report that the nitrogen-mobilizing plant metabolism that occurs during abiotic and biotic stress could be a 'slash-and-burn' defence strategy. In order to study nitrogen recycling and mobilization in host plants during pathogen attack and invasion, the Colletotrichum lindemuthianum/Phaseolus vulgaris interaction was used as a model. C. lindemuthianum is a hemibiotroph that causes anthracnose disease on P. vulgaris. Non-pathogenic mutants and the pathogenic wild-type strain were used to compare their effects on plant metabolism. The deleterious effects of infection were monitored by measuring changes in chlorophyll, protein, and amino acid concentrations. It was shown that amino acid composition changed depending on the plant-fungus interaction and that glutamine accumulated mainly in the leaves infected by the pathogenic strain. Glutamine accumulation correlated with the accumulation of cytosolic glutamine synthetase (GS1 alpha) mRNA. The most striking result was that the GS1 alpha gene was induced in all the fungus-infected leaves, independent of the strain used for inoculation, and that GS1 alpha expression paralleled the PAL3 and CHS defence gene expression. It is concluded that a role of GS1 alpha in plant defence has to be considered.

  4. Carbon translocation from a plant to an insect-pathogenic endophytic fungus

    Science.gov (United States)

    Behie, Scott W.; Moreira, Camila C.; Sementchoukova, Irina; Barelli, Larissa; Zelisko, Paul M.; Bidochka, Michael J.

    2017-01-01

    Metarhizium robertsii is a common soil fungus that occupies a specialized ecological niche as an endophyte and an insect pathogen. Previously, we showed that the endophytic capability and insect pathogenicity of Metarhizium are coupled to provide an active method of insect-derived nitrogen transfer to a host plant via fungal mycelia. We speculated that in exchange for this insect-derived nitrogen, the plant would provide photosynthate to the fungus. By using 13CO2, we show the incorporation of 13C into photosynthate and the subsequent translocation of 13C into fungal-specific carbohydrates (trehalose and chitin) in the root/endophyte complex. We determined the amount of 13C present in root-associated fungal biomass over a 21-day period by extracting fungal carbohydrates and analysing their composition using nuclear magnetic resonance (NMR) spectroscopy. These findings are evidence that the host plant is providing photosynthate to the fungus, likely in exchange for insect-derived nitrogen in a tripartite, and symbiotic, interaction. PMID:28098142

  5. Draft Genome Sequence of the Plant-Pathogenic Soil Fungus Rhizoctonia solani Anastomosis Group 3 Strain Rhs1AP

    Science.gov (United States)

    Cubeta, Marc A.; Dean, Ralph A.; Jabaji, Suha; Neate, Stephen M.; Tavantzis, Stellos; Toda, Takeshi; Vilgalys, Rytas; Bharathan, Narayanaswamy; Fedorova-Abrams, Natalie; Pakala, Suman B.; Pakala, Suchitra M.; Zafar, Nikhat; Joardar, Vinita; Losada, Liliana; Nierman, William C.

    2014-01-01

    The soil fungus Rhizoctonia solani is a pathogen of agricultural crops. Here, we report on the 51,705,945 bp draft consensus genome sequence of R. solani strain Rhs1AP. A comprehensive understanding of the heterokaryotic genome complexity and organization of R. solani may provide insight into the plant disease ecology and adaptive behavior of the fungus. PMID:25359908

  6. Bergamotane Sesquiterpenes with Alpha-Glucosidase Inhibitory Activity from the Plant Pathogenic Fungus Penicillium expansum.

    Science.gov (United States)

    Ying, You-Min; Fang, Cheng-An; Yao, Feng-Qi; Yu, Yuan; Shen, Ying; Hou, Zhuo-Ni; Wang, Zhen; Zhang, Wei; Shan, Wei-Guang; Zhan, Zha-Jun

    2017-01-01

    Two new bergamotane sesquiterpene lactones, named expansolides C and D (1 and 2), together with two known compounds expansolides A and B (3 and 4), were isolated from the plant pathogenic fungus Penicillium expansum ACCC37275. The structures of the new compounds were established by detailed analyses of the spectroscopic data, especially 1D-, 2D-NMR, and HR-ESI-MS. In an in vitro bioassay, the epimeric mixture of expansolides C and D (1 and 2) (in a ratio of 2:1 at the temprature of the bioassay) exhibited more potent α-glucosidase inhibitory activity (IC50 =0.50 ± 0.02 mm) as compared with the positive control acarbose (IC50 = 1.90 ± 0.05 mm). To the best of our knowledge, it was the first report on the α-glucosidase inhibitory activity of bergamotane sesquiterpenes.

  7. Antifungal activity against plant pathogens of metabolites from the endophytic fungus Cladosporium cladosporioides.

    Science.gov (United States)

    Wang, Xiaoning; Radwan, Mohamed M; Taráwneh, Amer H; Gao, Jiangtao; Wedge, David E; Rosa, Luiz H; Cutler, Horace G; Cutler, Stephen J

    2013-05-15

    Bioassay-guided fractionation of Cladosporium cladosporioides (Fresen.) de Vries extracts led to the isolation of four compounds, including cladosporin, 1; isocladosporin, 2; 5'-hydroxyasperentin, 3; and cladosporin-8-methyl ether, 4. An additional compound, 5',6-diacetylcladosporin, 5, was synthesized by acetylation of compound 3. Compounds 1-5 were evaluated for antifungal activity against plant pathogens. Phomopsis viticola was the most sensitive fungus to the tested compounds. At 30 μM, compound 1 exhibited 92.7, 90.1, 95.4, and 79.9% growth inhibition against Colletotrichum acutatum , Colletotrichum fragariae , Colletotrichum gloeosporioides , and P. viticola, respectively. Compound 2 showed 50.4, 60.2, and 83.0% growth inhibition at 30 μM against Co. fragariae, Co. gloeosporioides, and P. viticola, respectively. Compounds 3 and 4 were isolated for the first time from Cl. cladosporioides. Moreover, the identification of essential structural features of the cladosporin nuclei has also been evaluated. These structures provide new templates for the potential treatment and management of plant diseases.

  8. Proteome Analysis of the Plant Pathogenic Fungus Monilinia laxa Showing Host Specificity

    Directory of Open Access Journals (Sweden)

    Olja Bregar

    2012-01-01

    Full Text Available Brown rot fungus Monilinia laxa (Aderh. & Ruhl. Honey is an important plant pathogen in stone and pome fruits in Europe. We applied a proteomic approach in a study of M. laxa isolates obtained from apples and apricots in order to show the host specifity of the isolates and to analyse differentially expressed proteins in terms of host specifity, fungal pathogenicity and identification of candidate proteins for diagnostic marker development. Extracted mycelium proteins were separated by 2-D electrophoresis (2-DE and visualized by Coomassie staining in a non-linear pH range of 3–11 and Mr of 14–116 kDa. We set up a 2-DE reference map of M. laxa, resolving up to 800 protein spots, and used it for image analysis. The average technical coefficient of variance (13 % demonstrated a high reproducibility of protein extraction and 2-D polyacrylamide gel electrophoresis (2-DE PAGE, and the average biological coefficient of variance (23 % enabled differential proteomic analysis of the isolates. Multivariate statistical analysis (principal component analysis discriminated isolates from two different hosts, providing new data that support the existence of a M. laxa specialized form f. sp. mali, which infects only apples. A total of 50 differentially expressed proteins were further analyzed by LC-MS/MS, yielding 41 positive identifications. The identified mycelial proteins were functionally classified into 6 groups: amino acid and protein metabolism, energy production, carbohydrate metabolism, stress response, fatty acid metabolism and other proteins. Some proteins expressed only in apple isolates have been described as virulence factors in other fungi. The acetolactate synthase was almost 11-fold more abundant in apple-specific isolates than in apricot isolates and it might be implicated in M. laxa host specificity. Ten proteins identified only in apple isolates are potential candidates for the development of M. laxa host-specific diagnostic markers.

  9. Draft Genome Sequence of Sclerotinia borealis, a Psychrophilic Plant Pathogenic Fungus.

    Science.gov (United States)

    Mardanov, Andrey V; Beletsky, Alexey V; Kadnikov, Vitaly V; Ignatov, Alexander N; Ravin, Nikolai V

    2014-01-23

    Sclerotinia borealis is a necrotrophic phytopathogenic fungus notable for its wide host range and environmental persistence. It grows at low temperatures, causing snow mold disease of crop plants. To understand the molecular mechanisms of its pathogenesis and adaptation to the psychrophilic lifestyle, we determined the 39.3-Mb draft genome sequence of S. borealis F-4128.

  10. Molecular characterization of a novel hypovirus from the plant pathogenic fungus Fusarium graminearum.

    Science.gov (United States)

    Li, Pengfei; Zhang, Hailong; Chen, Xiaoguang; Qiu, Dewen; Guo, Lihua

    2015-07-01

    A novel mycovirus, termed Fusarium graminearum Hypovirus 2 (FgHV2/JS16), isolated from a plant pathogenic fungus, Fusarium graminearum strain JS16, was molecularly and biologically characterized. The genome of FgHV2/JS16 is 12,800 nucleotides (nts) long, excluding the poly (A) tail. This genome has only one large putative open reading frame, which encodes a polyprotein containing three normal functional domains, papain-like protease, RNA-dependent RNA polymerase, RNA helicase, and a novel domain with homologous bacterial SMC (structural maintenance of chromosomes) chromosome segregation proteins. A defective RNA segment that is 4553-nts long, excluding the poly (A) tail, was also detected in strain JS16. The polyprotein shared significant aa identities with Cryphonectria hypovirus 1 (CHV1) (16.8%) and CHV2 (16.2%). Phylogenetic analyses based on multiple alignments of the polyprotein clearly divided the members of Hypoviridae into two major groups, suggesting that FgHV2/JS16 was a novel hypovirus of a newly proposed genus-Alphahypovirus-composed of the members of Group 1, including CHV1, CHV2, FgHV1 and Sclerotinia sclerotiorum hypovirus 2. FgHV2/JS16 was shown to be associated with hypovirulence phenotypes according to comparisons of the biological properties shared between FgHV2/JS16-infected and FgHV2/JS16-free isogenic strains. Furthermore, we demonstrated that FgHV2/JS16 infection activated the RNA interference pathway in Fusarium graminearum by relative quantitative real time RT-PCR. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. The plant nitrogen mobilization promoted by Colletotrichum lindemuthianum in Phaseolus leaves depends on fungus pathogenicity

    National Research Council Canada - National Science Library

    Virginie Tavernier; Sandrine Cadiou; Karine Pageau; Richard Laugé; Michèle Reisdorf-Cren; Thierry Langin; Céline Masclaux-Daubresse

    2007-01-01

    .... In order to study nitrogen recycling and mobilization in host plants during pathogen attack and invasion, the Colletotrichum lindemuthianum/Phaseolus vulgaris interaction was used as a model. C...

  12. The role of strigolactones during plant interactions with the pathogenic fungus Fusarium oxysporum.

    Science.gov (United States)

    Foo, Eloise; Blake, Sara N; Fisher, Brendan J; Smith, Jason A; Reid, James B

    2016-06-01

    Strigolactones (SLs) do not influence spore germination or hyphal growth of Fusarium oxysporum. Mutant studies revealed no role for SLs but a role for ethylene signalling in defence against this pathogen in pea. Strigolactones (SLs) play important roles both inside the plant as a hormone and outside the plant as a rhizosphere signal in interactions with mycorrhizal fungi and parasitic weeds. What is less well understood is any potential role SLs may play in interactions with disease causing microbes such as pathogenic fungi. In this paper we investigate the influence of SLs on the hemibiotrophic pathogen Fusarium oxysporum f.sp. pisi both directly via their effects on fungal growth and inside the plant through the use of a mutant deficient in SL. Given that various stereoisomers of synthetic and naturally occuring SLs can display different biological activities, we used (+)-GR24, (-)-GR24 and the naturally occurring SL, (+)-strigol, as well as a racemic mixture of 5-deoxystrigol. As a positive control, we examined the influence of a plant mutant with altered ethylene signalling, ein2, on disease development. We found no evidence that SLs influence spore germination or hyphal growth of Fusarium oxysporum and that, while ethylene signalling influences pea susceptibility to this pathogen, SLs do not.

  13. De Novo Transcriptome Analysis of Plant Pathogenic Fungus Myrothecium roridum and Identification of Genes Associated with Trichothecene Mycotoxin Biosynthesis

    Directory of Open Access Journals (Sweden)

    Wei Ye

    2017-02-01

    Full Text Available Myrothecium roridum is a plant pathogenic fungus that infects different crops and decreases the yield of economical crops, including soybean, cotton, corn, pepper, and tomato. Until now, the pathogenic mechanism of M. roridum has remained unclear. Different types of trichothecene mycotoxins were isolated from M. roridum, and trichothecene was considered as a plant pathogenic factor of M. roridum. In this study, the transcriptome of M. roridum in different incubation durations was sequenced using an Illumina Hiseq 2000. A total of 35,485 transcripts and 25,996 unigenes for M. roridum were obtained from 8.0 Gb clean reads. The protein–protein network of the M. roridum transcriptome indicated that the mitogen-activated protein kinases signal pathway also played an important role in the pathogenicity of M. roridum. The genes related to trichothecene biosynthesis were annotated. The expression levels of these genes were also predicted and validated through quantitative real-time polymerase chain reaction. Tri5 gene encoding trichodiene synthase was cloned and expressed, and the purified trichodiene synthase was able to catalyze farnesyl pyrophosphate into different kinds of sesquiterpenoids.Tri4 and Tri11 genes were expressed in Escherichia coli, and their corresponding enzymatic properties were characterized. The phylogenetic tree of trichodiene synthase showed a great discrepancy between the trichodiene synthase from M. roridum and other species. Our study on the genes related to trichothecene biosynthesis establishes a foundation for the M. roridum hazard prevention, thus improving the yields of economical crops.

  14. Natural selection on coding and noncoding DNA sequences is associated with virulence genes in a plant pathogenic fungus.

    Science.gov (United States)

    Rech, Gabriel E; Sanz-Martín, José M; Anisimova, Maria; Sukno, Serenella A; Thon, Michael R

    2014-09-04

    Natural selection leaves imprints on DNA, offering the opportunity to identify functionally important regions of the genome. Identifying the genomic regions affected by natural selection within pathogens can aid in the pursuit of effective strategies to control diseases. In this study, we analyzed genome-wide patterns of selection acting on different classes of sequences in a worldwide sample of eight strains of the model plant-pathogenic fungus Colletotrichum graminicola. We found evidence of selective sweeps, balancing selection, and positive selection affecting both protein-coding and noncoding DNA of pathogenicity-related sequences. Genes encoding putative effector proteins and secondary metabolite biosynthetic enzymes show evidence of positive selection acting on the coding sequence, consistent with an Arms Race model of evolution. The 5' untranslated regions (UTRs) of genes coding for effector proteins and genes upregulated during infection show an excess of high-frequency polymorphisms likely the consequence of balancing selection and consistent with the Red Queen hypothesis of evolution acting on these putative regulatory sequences. Based on the findings of this work, we propose that even though adaptive substitutions on coding sequences are important for proteins that interact directly with the host, polymorphisms in the regulatory sequences may confer flexibility of gene expression in the virulence processes of this important plant pathogen. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  15. Molecular Characterization of a Trisegmented Mycovirus from the Plant Pathogenic Fungus Colletotrichum gloeosporioides

    Directory of Open Access Journals (Sweden)

    Jie Zhong

    2016-09-01

    Full Text Available A novel double-stranded RNA (dsRNA mycovirus, consisting of three dsRNA genome segments and possibly belonging to the family Chrysoviridae, was isolated from the filamentous phytopathogenic fungus Colletotrichum gloeosporioides and designated as Colletotrichum gloeosprioides chrysovirus 1 (CgCV1. The three dsRNAs of the CgCV1 genome with lengths of 3397, 2869, and 2630 bp (dsRNAs1–3 were found to contain a single open reading frame (ORF putatively encoding the RNA-dependent RNA polymerase (RdRp, a capsid protein, and a protease, respectively, all of which exhibited some degree of sequence similarity to the comparable putative proteins encoded by the genus Chrysovirus. The 5′- and 3′-untranslated regions in each dsRNA segment contained similar sequences that were strictly conserved at the termini. Moreover, isometric virus-like particles (VLPs with a diameter of approximately 40 nm were extracted from fungal mycelia. Phylogenetic analysis based on the conserved dsRNA1-encoded RdRp showed that CgCV1 is a new virus belonging to the Chrysoviridae family. BLAST analysis revealed the presence of CgCV1-like sequences in the chromosomes of Medicago truncatula and Solanum tuberosum. Moreover, some sequences in the transcriptome shotgun assembly (TSA library and expressed sequence tag database (ESTdb of other eudicot and monocot plants were also found to be related to CgCV1.

  16. Molecular Characterization of a Trisegmented Mycovirus from the Plant Pathogenic Fungus Colletotrichum gloeosporioides

    Science.gov (United States)

    Zhong, Jie; Pang, Xi Dan; Zhu, Hong Jian; Gao, Bi Da; Huang, Wen Kun; Zhou, Qian

    2016-01-01

    A novel double-stranded RNA (dsRNA) mycovirus, consisting of three dsRNA genome segments and possibly belonging to the family Chrysoviridae, was isolated from the filamentous phytopathogenic fungus Colletotrichum gloeosporioides and designated as Colletotrichum gloeosprioides chrysovirus 1 (CgCV1). The three dsRNAs of the CgCV1 genome with lengths of 3397, 2869, and 2630 bp (dsRNAs1–3) were found to contain a single open reading frame (ORF) putatively encoding the RNA-dependent RNA polymerase (RdRp), a capsid protein, and a protease, respectively, all of which exhibited some degree of sequence similarity to the comparable putative proteins encoded by the genus Chrysovirus. The 5′- and 3′-untranslated regions in each dsRNA segment contained similar sequences that were strictly conserved at the termini. Moreover, isometric virus-like particles (VLPs) with a diameter of approximately 40 nm were extracted from fungal mycelia. Phylogenetic analysis based on the conserved dsRNA1-encoded RdRp showed that CgCV1 is a new virus belonging to the Chrysoviridae family. BLAST analysis revealed the presence of CgCV1-like sequences in the chromosomes of Medicago truncatula and Solanum tuberosum. Moreover, some sequences in the transcriptome shotgun assembly (TSA) library and expressed sequence tag database (ESTdb) of other eudicot and monocot plants were also found to be related to CgCV1. PMID:27690081

  17. Cloning and functional characterization of BcatrA, a gene encoding an ABC transporter of the plant pathogenic fungus Botryotinia fuckeliana (Botrytis cinerea)

    NARCIS (Netherlands)

    Sorbo, Del G.; Ruocco, M.; Schoonbeek, H.; Scala, F.; Pane, C.; Vinale, F.; Waard, de M.A.

    2008-01-01

    BcatrA was cloned from the plant pathogenic fungus Botryotinia fuckeliana (Botrytis cinerea) and sequenced. Sequence analysis revealed that BcatrA encodes a protein composed of 1562 amino acid residues displaying high similarity with various fungal ATP-binding cassette (ABC) transporters having the

  18. Metabolism and metabolites of dithiocarbamates in the plant pathogenic fungus Leptosphaeria maculans.

    Science.gov (United States)

    Pedras, M Soledade C; Sarma-Mamillapalle, Vijay K

    2012-08-15

    Synthetic compounds containing a dithiocarbamate group are known to have a variety of biological effects and applications including antifungal, herbicidal, and insecticidal application. Leptosphaeria maculans is a fungal pathogen of crucifers able to detoxify efficiently the only plant natural product containing a dithiocarbamate group, the phytoalexin brassinin. To evaluate the effects of dithiocarbamates on L. maculans, a number of structurally diverse S-methyl dithiocarbamates containing indolyl, biphenyl, and benzimidazolyl moieties were synthesized, and their antifungal activities and metabolism by L. maculans were investigated. All dithiocarbamates were transformed by L. maculans through hydrolysis to the corresponding amines, which were less antifungal than the parent compounds. Two dithiocarbonates were shown to be much less antifungal than the corresponding dithiocarbamates. Results of this investigation indicate that S-methyl dithiocarbamates are not useful inhibitors of L. maculans and that their rates of transformation by L. maculans did not correlate with the antifungal activity of the particular compound.

  19. Epigenetic control of effector gene expression in the plant pathogenic fungus Leptosphaeria maculans.

    Directory of Open Access Journals (Sweden)

    Jessica L Soyer

    2014-03-01

    Full Text Available Plant pathogens secrete an arsenal of small secreted proteins (SSPs acting as effectors that modulate host immunity to facilitate infection. SSP-encoding genes are often located in particular genomic environments and show waves of concerted expression at diverse stages of plant infection. To date, little is known about the regulation of their expression. The genome of the Ascomycete Leptosphaeria maculans comprises alternating gene-rich GC-isochores and gene-poor AT-isochores. The AT-isochores harbor mosaics of transposable elements, encompassing one-third of the genome, and are enriched in putative effector genes that present similar expression patterns, namely no expression or low-level expression during axenic cultures compared to strong induction of expression during primary infection of oilseed rape (Brassica napus. Here, we investigated the involvement of one specific histone modification, histone H3 lysine 9 methylation (H3K9me3, in epigenetic regulation of concerted effector gene expression in L. maculans. For this purpose, we silenced the expression of two key players in heterochromatin assembly and maintenance, HP1 and DIM-5 by RNAi. By using HP1-GFP as a heterochromatin marker, we observed that almost no chromatin condensation is visible in strains in which LmDIM5 was silenced by RNAi. By whole genome oligoarrays we observed overexpression of 369 or 390 genes, respectively, in the silenced-LmHP1 and -LmDIM5 transformants during growth in axenic culture, clearly favouring expression of SSP-encoding genes within AT-isochores. The ectopic integration of four effector genes in GC-isochores led to their overexpression during growth in axenic culture. These data strongly suggest that epigenetic control, mediated by HP1 and DIM-5, represses the expression of at least part of the effector genes located in AT-isochores during growth in axenic culture. Our hypothesis is that changes of lifestyle and a switch toward pathogenesis lift chromatin

  20. Host-targeting-motif Harbored Secretary Proteins in Genome of Plant Pathogenic Fungus Botrytis cinerea

    Institute of Scientific and Technical Information of China (English)

    Zhang Yue; Chen Zi-niu; Su Yuan; Yu Lei

    2012-01-01

    According to our previous study, saprophytic fungi Botrytis cinerea contained 579 predicted secretary proteins. Among them, we found that 122 of these proteins contained the highly conserved pathogenic-related host-targeting-motif RxLx within 100 residues adjacent to the signal peptide cleavage site. According to PEDNAT and COG of the GenBank database, the functions of this motif containing proteins included metabolism modification and cell secretion. We blasted them in GenBank and found 47.54% had highly conserved homologues in other species, among them 74.1% had putative functional domains. This suggests these proteins are presumably ancient and vertically transmitted within the species. Many of these domains belonged to proteins which played roles in the pathogenic process of other kinds of pathogens and some had already been proved to be pathogenic secretary proteins of Botrytis cinerea. So we postulated that proteins contained host-targeting-motif RxLx were candidates participating in the pathogenesis of Botrytis cinerea.

  1. Effect of plant extracts and a disinfectant on biological parameters and pathogenicity of the fungus Beauveria bassiana (Bals.) Vuill. (Ascomycota: Cordycipitaceae).

    Science.gov (United States)

    Martins, C C; Alves, L F A; Mamprim, A P

    2016-06-01

    The fungus Beauveria bassiana is naturally found in poultry houses and causes high rates of mortality in Alphitobius diaperinus. Laboratory and field experiments have shown the potential of this fungus as an insect control agent. However, in poultry houses, bacteria as Salmonella, can be found and have been studied alternative control methods for this pathogen. Thus, this study aimed to evaluate the effect of plant extracts and a disinfectant on the fungus Beauveria bassiana (strain Unioeste 4). Conidial viability, colony-forming unit (CFU) counts, vegetative growth, conidia production, insecticidal activity of the fungus and compatibility were used as parameters in the evaluation of the effect of these products on the fungus. Alcoholic and aqueous extracts of jabuticaba (Myrciaria cauliflora (Mart.), guava (Psidium guajava (L.)), and jambolan (Syzygium cumini (L.), at concentrations of 10% as well as the commercial disinfectant, Peroxitane® 1512 AL, were evaluated at the recommended concentrations (RC), 1:200 (RC), 0.5 RC and 2 RC. There was a negative influence of alcoholic and aqueous extracts of jabuticaba, guava and three dilutions of Peroxitane on the viability of conidia. The CFUs and vegetative growth of the fungus were affected only by the Peroxitane (all dilutions). For conidial production, the aqueous extract of guava had a positive effect, increasing production, while the Peroxitane at the R and RC concentrations resulted in a negative influence. The mortality of A. diaperinus, caused by the fungus after exposure to these products, was 60% for the peracetic acid at 0.5 RC, and above 80% for the extracts. Thus, the results showed that all the extracts and Peroxitane at RC 0.5 are compatible with the fungus B. bassiana Unioeste 4, however only the extracts had a low impact on inoculum potential.

  2. Effect of plant extracts and a disinfectant on biological parameters and pathogenicity of the fungus Beauveria bassiana (Bals. Vuill. (Ascomycota: Cordycipitaceae

    Directory of Open Access Journals (Sweden)

    C. C. Martins

    Full Text Available Abstract The fungus Beauveria bassiana is naturally found in poultry houses and causes high rates of mortality in Alphitobius diaperinus. Laboratory and field experiments have shown the potential of this fungus as an insect control agent. However, in poultry houses, bacteria as Salmonella, can be found and have been studied alternative control methods for this pathogen. Thus, this study aimed to evaluate the effect of plant extracts and a disinfectant on the fungus Beauveria bassiana (strain Unioeste 4. Conidial viability, colony-forming unit (CFU counts, vegetative growth, conidia production, insecticidal activity of the fungus and compatibility were used as parameters in the evaluation of the effect of these products on the fungus. Alcoholic and aqueous extracts of jabuticaba (Myrciaria cauliflora (Mart., guava (Psidium guajava (L., and jambolan (Syzygium cumini (L., at concentrations of 10% as well as the commercial disinfectant, Peroxitane® 1512 AL, were evaluated at the recommended concentrations (RC, 1:200 (RC, 0.5 RC and 2 RC. There was a negative influence of alcoholic and aqueous extracts of jabuticaba, guava and three dilutions of Peroxitane on the viability of conidia. The CFUs and vegetative growth of the fungus were affected only by the Peroxitane (all dilutions. For conidial production, the aqueous extract of guava had a positive effect, increasing production, while the Peroxitane at the R and RC concentrations resulted in a negative influence. The mortality of A. diaperinus, caused by the fungus after exposure to these products, was 60% for the peracetic acid at 0.5 RC, and above 80% for the extracts. Thus, the results showed that all the extracts and Peroxitane at RC 0.5 are compatible with the fungus B. bassiana Unioeste 4, however only the extracts had a low impact on inoculum potential.

  3. Plants promote mating and dispersal of the human pathogenic fungus Cryptococcus

    Science.gov (United States)

    Mohan, Rajinikanth; Heitman, Joseph

    2017-01-01

    Infections due to Cryptococcus are a leading cause of fungal infections worldwide and are acquired as a result of environmental exposure to desiccated yeast or spores. The ability of Cryptococcus to grow, mate, and produce infectious propagules in association with plants is important for the maintenance of the genetic diversity and virulence factors important for infection of animals and humans. In the Western United States and Canada, Cryptococcus has been associated with conifers and tree species other than Eucalyptus; however, to date Cryptococcus has only been studied on live Arabidopsis thaliana, Eucalyptus sp., and Terminalia catappa (almond) seedlings. Previous research has demonstrated the ability of Cryptococcus to colonize live plants, leaves, and vasculature. We investigated the ability of Cryptococcus to grow on live seedlings of the angiosperms, A. thaliana, Eucalyptus camaldulensis, Colophospermum mopane, and the gymnosperms, Pseudotsuga menziesii (Douglas fir), and Tsuga heterophylla (Western hemlock). We observed a broad-range ability of Cryptococcus to colonize both traditional infection models as well as newly tested conifer species. Furthermore, C. neoformans, C. deneoformans, C. gattii (VGI), C. deuterogattii (VGII) and C. bacillisporus (VGIII) were able to colonize live plant leaves and needles but also undergo filamentation and mating on agar seeded with plant materials or in saprobic association with dead plant materials. The ability of Cryptococcus to grow and undergo filamentation and reproduction in saprobic association with both angiosperms and gymnosperms highlights an important role of plant debris in the sexual cycle and exposure to infectious propagules. This study highlights the broad importance of plants (and plant debris) as the ecological niche and reservoirs of infectious propagules of Cryptococcus in the environment. PMID:28212396

  4. Plants promote mating and dispersal of the human pathogenic fungus Cryptococcus.

    Science.gov (United States)

    Springer, Deborah J; Mohan, Rajinikanth; Heitman, Joseph

    2017-01-01

    Infections due to Cryptococcus are a leading cause of fungal infections worldwide and are acquired as a result of environmental exposure to desiccated yeast or spores. The ability of Cryptococcus to grow, mate, and produce infectious propagules in association with plants is important for the maintenance of the genetic diversity and virulence factors important for infection of animals and humans. In the Western United States and Canada, Cryptococcus has been associated with conifers and tree species other than Eucalyptus; however, to date Cryptococcus has only been studied on live Arabidopsis thaliana, Eucalyptus sp., and Terminalia catappa (almond) seedlings. Previous research has demonstrated the ability of Cryptococcus to colonize live plants, leaves, and vasculature. We investigated the ability of Cryptococcus to grow on live seedlings of the angiosperms, A. thaliana, Eucalyptus camaldulensis, Colophospermum mopane, and the gymnosperms, Pseudotsuga menziesii (Douglas fir), and Tsuga heterophylla (Western hemlock). We observed a broad-range ability of Cryptococcus to colonize both traditional infection models as well as newly tested conifer species. Furthermore, C. neoformans, C. deneoformans, C. gattii (VGI), C. deuterogattii (VGII) and C. bacillisporus (VGIII) were able to colonize live plant leaves and needles but also undergo filamentation and mating on agar seeded with plant materials or in saprobic association with dead plant materials. The ability of Cryptococcus to grow and undergo filamentation and reproduction in saprobic association with both angiosperms and gymnosperms highlights an important role of plant debris in the sexual cycle and exposure to infectious propagules. This study highlights the broad importance of plants (and plant debris) as the ecological niche and reservoirs of infectious propagules of Cryptococcus in the environment.

  5. Biolistic transformation of the obligate plant pathogenic fungus, Erysiphe graminis f.sp. hordei

    DEFF Research Database (Denmark)

    Christiansen, S.K.; Knudsen, S.; Giese, H.

    1995-01-01

    Particle gun acceleration appears to be a possible way to transform mycelium cells of obligate plant parasites growing on host surfaces, GUS expression was obtained in E. graminis f.sp. hordei cells after bombardment with the GUS gene under the control of the E. graminis f.sp. hordei beta...

  6. Comparative Genomics of a Plant-Pathogenic Fungus, Pyrenophora tritici-repentis, Reveals Transduplication and the Impact of Repeat Elements on Pathogenicity and Population Divergence

    Energy Technology Data Exchange (ETDEWEB)

    Manning, Viola A.; Pandelova, Iovanna; Dhillon, Braham; Wilhelm, Larry J.; Goodwin, Stephen B.; Berlin, Aaron M.; Figueroa, Melania; Freitag, Michael; Hane, James K.; Henrissat, Bernard; Holman, Wade H.; Kodira, Chinnappa D.; Martin, Joel; Oliver, Richard P.; Robbertse, Barbara; Schackwitz, Wendy; Schwartz, David C.; Spatafora, Joseph W.; Turgeon, B. Gillian; Yandava, Chandri; Young, Sarah; Zhou, Shiguo; Zeng, Qiandong; Grigoriev, Igor V.; Ma, Li-Jun; Ciuffetti, Lynda M.

    2012-08-16

    Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes.

  7. Interspecific Comparison and annotation of two complete mitochondrial genome sequences from the plant pathogenic fungus Mycosphaerella graminicola

    Energy Technology Data Exchange (ETDEWEB)

    Millenbaugh, Bonnie A; Pangilinan, Jasmyn L.; Torriani, Stefano F.F.; Goodwin, Stephen B.; Kema, Gert H.J.; McDonald, Bruce A.

    2007-12-07

    The mitochondrial genomes of two isolates of the wheat pathogen Mycosphaerella graminicola were sequenced completely and compared to identify polymorphic regions. This organism is of interest because it is phylogenetically distant from other fungi with sequenced mitochondrial genomes and it has shown discordant patterns of nuclear and mitochondrial diversity. The mitochondrial genome of M. graminicola is a circular molecule of approximately 43,960 bp containing the typical genes coding for 14 proteins related to oxidative phosphorylation, one RNA polymerase, two rRNA genes and a set of 27 tRNAs. The mitochondrial DNA of M. graminicola lacks the gene encoding the putative ribosomal protein (rps5-like), commonly found in fungal mitochondrial genomes. Most of the tRNA genes were clustered with a gene order conserved with many other ascomycetes. A sample of thirty-five additional strains representing the known global mt diversity was partially sequenced to measure overall mitochondrial variability within the species. Little variation was found, confirming previous RFLP-based findings of low mitochondrial diversity. The mitochondrial sequence of M. graminicola is the first reported from the family Mycosphaerellaceae or the order Capnodiales. The sequence also provides a tool to better understand the development of fungicide resistance and the conflicting pattern of high nuclear and low mitochondrial diversity in global populations of this fungus.

  8. Genome-wide profiling of DNA methylation provides insights into epigenetic regulation of fungal development in a plant pathogenic fungus, Magnaporthe oryzae.

    Science.gov (United States)

    Jeon, Junhyun; Choi, Jaeyoung; Lee, Gir-Won; Park, Sook-Young; Huh, Aram; Dean, Ralph A; Lee, Yong-Hwan

    2015-02-24

    DNA methylation is an important epigenetic modification that regulates development of plants and mammals. To investigate the roles of DNA methylation in fungal development, we profiled genome-wide methylation patterns at single-nucleotide resolution during vegetative growth, asexual reproduction, and infection-related morphogenesis in a model plant pathogenic fungus, Magnaporthe oryzae. We found that DNA methylation occurs in and around genes as well as transposable elements and undergoes global reprogramming during fungal development. Such reprogramming of DNA methylation suggests that it may have acquired new roles other than controlling the proliferation of TEs. Genetic analysis of DNA methyltransferase deletion mutants also indicated that proper reprogramming in methylomes is required for asexual reproduction in the fungus. Furthermore, RNA-seq analysis showed that DNA methylation is associated with transcriptional silencing of transposable elements and transcript abundance of genes in context-dependent manner, reinforcing the role of DNA methylation as a genome defense mechanism. This comprehensive approach suggests that DNA methylation in fungi can be a dynamic epigenetic entity contributing to fungal development and genome defense. Furthermore, our DNA methylomes provide a foundation for future studies exploring this key epigenetic modification in fungal development and pathogenesis.

  9. Screening of Fungus Antagonists against Six Main Disease Pathogens in Crops

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    28 soil samples were collected from the rhizosphere of 16 plant species in six different districts in Hunan. As a result of isolation and purification, 122 fungus strains were obtained of which the antagonistic activity was tested against six fungus pathogens in tomato, cotton, cucumber, chilli, rice and rape, and 17 strains were found antagonistic to one or more pathogenic fungi.

  10. An STE12 gene identified in the mycorrhizal fungus Glomus intraradices restores infectivity of a hemibiotrophic plant pathogen.

    Science.gov (United States)

    Tollot, Marie; Wong Sak Hoi, Joanne; van Tuinen, Diederik; Arnould, Christine; Chatagnier, Odile; Dumas, Bernard; Gianinazzi-Pearson, Vivienne; Seddas, Pascale M A

    2009-01-01

    Mechanisms of root penetration by arbuscular mycorrhizal (AM) fungi are unknown and investigations are hampered by the lack of transformation systems for these unculturable obligate biotrophs. Early steps of host infection by hemibiotrophic fungal phytopathogens, sharing common features with those of AM fungal colonization, depend on the transcription factor STE12. Using degenerated primers and rapid amplification of cDNA ends, we isolated the full-length cDNA of an STE12-like gene, GintSTE, from Glomus intraradices and profiled GintSTE expression by real-time and in situ RT-PCR. GintSTE activity and function were investigated by heterologous complementation of a yeast ste12Delta mutant and a Colletotrichum lindemuthianum clste12Delta mutant. * Sequence data indicate that GintSTE is similar to STE12 from hemibiotrophic plant pathogens, especially Colletotrichum spp. Introduction of GintSTE into a noninvasive mutant of C. lindemuthianum restored fungal infectivity of plant tissues. GintSTE expression was specifically localized in extraradicular fungal structures and was up-regulated when G. intraradices penetrated roots of wild-type Medicago truncatula as compared with an incompatible mutant. Results suggest a possible role for GintSTE in early steps of root penetration by AM fungi, and that pathogenic and symbiotic fungi may share common regulatory mechanisms for invasion of plant tissues.

  11. Recent range expansion and agricultural landscape heterogeneity have only minimal effect on the spatial genetic structure of the plant pathogenic fungus Mycosphaerella fijiensis.

    Science.gov (United States)

    Rieux, A; De Lapeyre De Bellaire, L; Zapater, M-F; Ravigne, V; Carlier, J

    2013-01-01

    Understanding how geographical and environmental features affect genetic variation at both the population and individual levels is crucial in biology, especially in the case of pathogens. However, distinguishing between these factors and the effects of historical range expansion on spatial genetic structure remains challenging. In the present study, we investigated the case of Mycosphaerella fijiensis-a plant pathogenic fungus that has recently colonized an agricultural landscape characterized by the presence of potential barriers to gene flow, including several commercial plantations in which disease control practises such as the use of fungicides are applied frequently, and low host density areas. We first genotyped 300 isolates sampled at a global scale on untreated plants in two dimensions over a 50 × 80-km area. Using two different clustering algorithms, no genetic structure was detected in the studied area, suggesting expansion of large populations and/or no influence of potential barriers. Second, we investigated the potential effect of disease control practises on M. fijiensis diversity by comparing populations sampled in commercial vs food-crop plantations. At this local scale, we detected significantly higher allelic richness inside commercial plantations compared with the surrounding food-crop plantation populations. Analysis of molecular variance indicated that 99% of the total genetic variance occurred within populations. We discuss the suggestion that high population size and/or high migration rate between populations might be responsible for the absence of any effect of disease control practises on genetic diversity and differentiation.

  12. Growth under visible light increases conidia and mucilage production and tolerance to UV-B radiation in the plant pathogenic fungus Colletotrichum acutatum.

    Science.gov (United States)

    de Menezes, Henrique D; Massola, Nelson S; Flint, Stephan D; Silva, Geraldo J; Bachmann, Luciano; Rangel, Drauzio E N; Braga, Gilberto U L

    2015-01-01

    Light conditions can influence fungal development. Some spectral wavebands can induce conidial production, whereas others can kill the conidia, reducing the population size and limiting dispersal. The plant pathogenic fungus Colletotrichum acutatum causes anthracnose in several crops. During the asexual stage on the host plant, Colletototrichum produces acervuli with abundant mucilage-embedded conidia. These conidia are responsible for fungal dispersal and host infection. This study examined the effect of visible light during C. acutatum growth on the production of conidia and mucilage and also on the UV tolerance of these conidia. Conidial tolerance to an environmentally realistic UV irradiance was determined both in conidia surrounded by mucilage on sporulating colonies and in conidial suspension. Exposures to visible light during fungal growth increased production of conidia and mucilage as well as conidial tolerance to UV. Colonies exposed to light produced 1.7 times more conidia than colonies grown in continuous darkness. The UV tolerances of conidia produced under light were at least two times higher than conidia produced in the dark. Conidia embedded in the mucilage on sporulating colonies were more tolerant of UV than conidia in suspension that were washed free of mucilage. Conidial tolerance to UV radiation varied among five selected isolates. © 2014 The American Society of Photobiology.

  13. Functional genomics in the rice blast fungus to unravel the fungal pathogenicity

    Institute of Scientific and Technical Information of China (English)

    Junhyun JEON; Jaehyuk CHOI; Jongsun PARK; Yong-Hwan LEE

    2008-01-01

    A rapidly growing number of successful genome sequencing projects in plant pathogenic fungi greatly increase the demands for tools and methodologies to study fungal pathogenicity at genomic scale. Magnaporthe oryzae is an economically important plant pathogenic fungus whose genome is fully sequenced. Recently we have reported the development and application of functional genomics platform technologies in M. oryzae. This model approach would have many practical ramifications in design and implementation of upcoming functional genomics studies of filamentous fungi aimed at understanding fungal pathogenicity.

  14. The PYR1 gene of the plant pathogenic fungus Colletotrichum graminicola: selection by intraspecific complementation and sequence analysis.

    Science.gov (United States)

    Rasmussen, J B; Panaccione, D G; Fang, G C; Hanau, R M

    1992-10-01

    A spontaneous uridine-requiring auxotroph of Colletotrichum graminicola was recovered by selection for resistance to 5-fluoro-orotic acid. The auxotroph lacked orotate phosphoribosyl transferase (OPRTase) and was complemented with a clone from a cosmid library of C. graminicola DNA. A 3.1 kb HindIII-SalI fragment was subcloned from the cosmid and it could efficiently transform the auxotrophic strain to uridine prototrophy and integrate by site-specific recombination. This DNA fragment contains an open reading frame that is similar to OPRTase genes of the fungi Sordaria macrospora, Trichoderma reesei, Podospora anserina, and Saccharomyces cerevisiae. Based on the sequence similarities and the ability to restore uridine prototrophy, we conclude that the fragment contains the C. graminicola gene for OPRTase, which we have named PYR1. Our results demonstrate that cloning by complementation is feasible in C. graminicola, that the gene for OPRTase from C. graminicola can be useful as a selectable marker in transformation of the fungus, and that the OPRTase gene product is similar to OPRTase from other fungi.

  15. Genome Sequence of the Pathogenic Fungus Sporothrix schenckii (ATCC 58251).

    Science.gov (United States)

    Cuomo, Christina A; Rodriguez-Del Valle, Nuri; Perez-Sanchez, Lizaida; Abouelleil, Amr; Goldberg, Jonathan; Young, Sarah; Zeng, Qiandong; Birren, Bruce W

    2014-05-22

    Sporothrix schenckii is a pathogenic dimorphic fungus that grows as a yeast and as mycelia. This species is the causative agent of sporotrichosis, typically a skin infection. We report the genome sequence of S. schenckii, which will facilitate the study of this fungus and of the Sporothrix schenckii group.

  16. Pathogen Phytosensing: Plants to Report Plant Pathogens

    Directory of Open Access Journals (Sweden)

    C. Neal Stewart

    2008-04-01

    Full Text Available Real-time systems that provide evidence of pathogen contamination in crops can be an important new line of early defense in agricultural centers. Plants possess defense mechanisms to protect against pathogen attack. Inducible plant defense is controlled by signal transduction pathways, inducible promoters and cis-regulatory elements corresponding to key genes involved in defense, and pathogen-specific responses. Identified inducible promoters and cis-acting elements could be utilized in plant sentinels, or ‘phytosensors’, by fusing these to reporter genes to produce plants with altered phenotypes in response to the presence of pathogens. Here, we have employed cis-acting elements from promoter regions of pathogen inducible genes as well as those responsive to the plant defense signal molecules salicylic acid, jasmonic acid, and ethylene. Synthetic promoters were constructed by combining various regulatory elements supplemented with the enhancer elements from the Cauliflower mosaic virus (CaMV 35S promoter to increase basal level of the GUS expression. The inducibility of each synthetic promoter was first assessed in transient expression assays using Arabidopsis thaliana protoplasts and then examined for efficacy in stably transgenic Arabidopsis and tobacco plants. Histochemical and fluorometric GUS expression analyses showed that both transgenic Arabidopsis and tobacco plants responded to elicitor and phytohormone treatments with increased GUS expression when compared to untreated plants. Pathogen-inducible phytosensor studies were initiated by analyzing the sensitivity of the synthetic promoters against virus infection. Transgenic tobacco plants infected with Alfalfa mosaic virus showed an increase in GUS expression when compared to mock-inoculated control plants, whereas Tobacco mosaic virus infection caused no changes in GUS expression. Further research, using these transgenic plants against a range of different

  17. Comparative Genomics Including the Early-Diverging Smut Fungus Ceraceosorus bombacis Reveals Signatures of Parallel Evolution within Plant and Animal Pathogens of Fungi and Oomycetes.

    Science.gov (United States)

    Sharma, Rahul; Xia, Xiaojuan; Riess, Kai; Bauer, Robert; Thines, Marco

    2015-08-27

    Ceraceosorus bombacis is an early-diverging lineage of smut fungi and a pathogen of cotton trees (Bombax ceiba). To study the evolutionary genomics of smut fungi in comparison with other fungal and oomycete pathogens, the genome of C. bombacis was sequenced and comparative genomic analyses were performed. The genome of 26.09 Mb encodes for 8,024 proteins, of which 576 are putative-secreted effector proteins (PSEPs). Orthology analysis revealed 30 ortholog PSEPs among six Ustilaginomycotina genomes, the largest groups of which are lytic enzymes, such as aspartic peptidase and glycoside hydrolase. Positive selection analyses revealed the highest percentage of positively selected PSEPs in C. bombacis compared with other Ustilaginomycotina genomes. Metabolic pathway analyses revealed the absence of genes encoding for nitrite and nitrate reductase in the genome of the human skin pathogen Malassezia globosa, but these enzymes are present in the sequenced plant pathogens in smut fungi. Interestingly, these genes are also absent in cultivable oomycete animal pathogens, while nitrate reductase has been lost in cultivable oomycete plant pathogens. Similar patterns were also observed for obligate biotrophic and hemi-biotrophic fungal and oomycete pathogens. Furthermore, it was found that both fungal and oomycete animal pathogen genomes are lacking cutinases and pectinesterases. Overall, these findings highlight the parallel evolution of certain genomic traits, revealing potential common evolutionary trajectories among fungal and oomycete pathogens, shaping the pathogen genomes according to their lifestyle.

  18. The plant pathogenic fungus Gaeumannomyces graminis var. tritici improves bacterial growth and triggers early gene regulations in the biocontrol strain Pseudomonas fluorescens Pf29Arp.

    Science.gov (United States)

    Barret, M; Frey-Klett, P; Boutin, M; Guillerm-Erckelboudt, A-Y; Martin, F; Guillot, L; Sarniguet, A

    2009-01-01

    In soil, some antagonistic rhizobacteria contribute to reduce root diseases caused by phytopathogenic fungi. Direct modes of action of these bacteria have been largely explored; however, commensal interaction also takes place between these microorganisms and little is known about the influence of filamentous fungi on bacteria. An in vitro confrontation bioassay between the pathogenic fungus Gaeumannomyces graminis var. tritici (Ggt) and the biocontrol bacterial strain Pseudomonas fluorescens Pf29Arp was set up to analyse bacterial transcriptional changes induced by the fungal mycelium at three time-points of the interaction before cell contact and up until contact. For this, a Pf29Arp shotgun DNA microarray was constructed. Specifity of Ggt effect was assessed in comparison with one of two other filamentous fungi, Laccaria bicolor and Magnaporthe grisea. During a commensal interaction, Ggt increased the growth rate of Pf29Arp. Before contact, Ggt induced bacterial genes involved in mycelium colonization. At contact, genes encoding protein of stress response and a patatin-like protein were up-regulated. Among all the bacterial genes identified, xseB was specifically up-regulated at contact by Ggt but down-regulated by the other fungi. Data showed that the bacterium sensed the presence of the fungus early, but the main gene alteration occurred during bacterial-fungal cell contact.

  19. 454-pyrosequencing of Coffea arabica leaves infected by the rust fungus Hemileia vastatrix reveals in planta-expressed pathogen-secreted proteins and plant functions in a late compatible plant-rust interaction.

    Science.gov (United States)

    Fernandez, Diana; Tisserant, Emilie; Talhinhas, Pedro; Azinheira, Helena; Vieira, Ana; Petitot, Anne-Sophie; Loureiro, Andreia; Poulain, Julie; Da Silva, Corinne; Silva, Maria Do Céu; Duplessis, Sébastien

    2012-01-01

    Coffee (Coffea arabica L.), one of the key export and cash crops in tropical and subtropical countries, suffers severe losses from the rust fungus Hemileia vastatrix. The transcriptome of H. vastatrix was analysed during a compatible interaction with coffee to obtain an exhaustive repertoire of the genes expressed during infection and to identify potential effector genes. Large-scale sequencing (454-GS-FLEX Titanium) of mixed coffee and rust cDNAs obtained from 21-day rust-infected leaves generated 352 146 sequences which assembled into 22 774 contigs. In the absence of any reference genomic sequences for Coffea or Hemileia, specific trinucleotide frequencies within expressed sequence tags (ESTs) and blast homology against a set of dicots and basidiomycete genomes were used to distinguish pathogen from plant sequences. About 30% (6763) of the contigs were assigned to H. vastatrix and 61% (13 951) to C. arabica. The majority (60%) of the rust sequences did not show homology to any genomic database, indicating that they were potential novel fungal genes. In silico analyses of the 6763 H. vastatrix contigs predicted 382 secreted proteins and identified homologues of the flax rust haustorially expressed secreted proteins (HESPs) and bean rust transferred protein 1 (RTP1). These rust candidate effectors showed conserved amino-acid domains and conserved patterns of cysteine positions suggestive of conserved functions during infection of host plants. Quantitative reverse transcription-polymerase chain reaction profiling of selected rust genes revealed dynamic expression patterns during the time course of infection of coffee leaves. This study provides the first valuable genomic resource for the agriculturally important plant pathogen H. vastatrix and the first comprehensive C. arabica EST dataset.

  20. Plant pathogen resistance

    Science.gov (United States)

    Greenberg, Jean T; Jung, Ho Won; Tschaplinski, Timothy

    2012-11-27

    Azelaic acid or its derivatives or analogs induce a robust and a speedier defense response against pathogens in plants. Azelaic acid treatment alone does not induce many of the known defense-related genes but activates a plant's defense signaling upon pathogen exposure.

  1. Plant pathogen resistance

    Energy Technology Data Exchange (ETDEWEB)

    Greenberg, Jean T.; Jung, Ho Won; Tschaplinski, Timothy

    2015-10-20

    Azelaic acid or its derivatives or analogs induce a robust and a speedier defense response against pathogens in plants. Azelaic acid treatment alone does not induce many of the known defense-related genes but activates a plant's defense signaling upon pathogen exposure.

  2. Advances on Plant Pathogenic Mycotoxin Binding Proteins

    Institute of Scientific and Technical Information of China (English)

    WANG Chao-hua; DONG Jin-gao

    2002-01-01

    Toxin-binding protein is one of the key subjects in plant pathogenic mycotoxin research. In this paper, new advances in toxin-binding proteins of 10 kinds of plant pathogenic mycotoxins belonging to Helminthosporium ,Alternaria ,Fusicoccum ,Verticillium were reviewed, especially the techniques and methods of toxin-binding proteins of HS-toxin, HV-toxin, HMT-toxin, HC-toxin. It was proposed that the isotope-labeling technique and immunological chemistry technique should be combined together in research of toxin-binding protein, which will be significant to study the molecular recognition mechanism between host and pathogenic fungus.

  3. Secondary metabolite arsenal of an opportunistic pathogenic fungus.

    Science.gov (United States)

    Bignell, Elaine; Cairns, Timothy C; Throckmorton, Kurt; Nierman, William C; Keller, Nancy P

    2016-12-05

    Aspergillus fumigatus is a versatile fungus able to successfully exploit diverse environments from mammalian lungs to agricultural waste products. Among its many fitness attributes are dozens of genetic loci containing biosynthetic gene clusters (BGCs) producing bioactive small molecules (often referred to as secondary metabolites or natural products) that provide growth advantages to the fungus dependent on environment. Here we summarize the current knowledge of these BGCs-18 of which can be named to product-their expression profiles in vivo, and which BGCs may enhance virulence of this opportunistic human pathogen. Furthermore, we find extensive evidence for the presence of many of these BGCs, or similar BGCs, in distantly related genera including the emerging pathogen Pseudogymnoascus destructans, the causative agent of white-nose syndrome in bats, and suggest such BGCs may be predictive of pathogenic potential in other fungi.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.

  4. One fungus, one name promotes progressive plant pathology.

    Science.gov (United States)

    Wingfield, Michael J; De Beer, Z Wilhelm; Slippers, Bernard; Wingfield, Brenda D; Groenewald, Johannes Z; Lombard, Lorenzo; Crous, Pedro W

    2012-08-01

    The robust and reliable identification of fungi underpins virtually every element of plant pathology, from disease diagnosis to studies of biology, management/control, quarantine and, even more recently, comparative genomics. Most plant diseases are caused by fungi, typically pleomorphic organisms, for which the taxonomy and, in particular, a dual nomenclature system have frustrated and confused practitioners of plant pathology. The emergence of DNA sequencing has revealed cryptic taxa and revolutionized our understanding of relationships in the fungi. The impacts on plant pathology at every level are already immense and will continue to grow rapidly as new DNA sequencing technologies continue to emerge. DNA sequence comparisons, used to resolve a dual nomenclature problem for the first time only 19 years ago, have made it possible to approach a natural classification for the fungi and to abandon the confusing dual nomenclature system. The journey to a one fungus, one name taxonomic reality has been long and arduous, but its time has come. This will inevitably have a positive impact on plant pathology, plant pathologists and future students of this hugely important discipline on which the world depends for food security and plant health in general. This contemporary review highlights the problems of a dual nomenclature, especially its impact on plant pathogenic fungi, and charts the road to a one fungus, one name system that is rapidly drawing near. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

  5. Genomic insight into pathogenicity of dematiaceous fungus Corynespora cassiicola

    Science.gov (United States)

    Looi, Hong Keat; Toh, Yue Fen; Yew, Su Mei; Na, Shiang Ling; Tan, Yung-Chie; Chong, Pei-Sin; Khoo, Jia-Shiun; Yee, Wai-Yan; Ng, Kee Peng

    2017-01-01

    Corynespora cassiicola is a common plant pathogen that causes leaf spot disease in a broad range of crop, and it heavily affect rubber trees in Malaysia (Hsueh, 2011; Nghia et al., 2008). The isolation of UM 591 from a patient’s contact lens indicates the pathogenic potential of this dematiaceous fungus in human. However, the underlying factors that contribute to the opportunistic cross-infection have not been fully studied. We employed genome sequencing and gene homology annotations in attempt to identify these factors in UM 591 using data obtained from publicly available bioinformatics databases. The assembly size of UM 591 genome is 41.8 Mbp, and a total of 13,531 (≥99 bp) genes have been predicted. UM 591 is enriched with genes that encode for glycoside hydrolases, carbohydrate esterases, auxiliary activity enzymes and cell wall degrading enzymes. Virulent genes comprising of CAZymes, peptidases, and hypervirulence-associated cutinases were found to be present in the fungal genome. Comparative analysis result shows that UM 591 possesses higher number of carbohydrate esterases family 10 (CE10) CAZymes compared to other species of fungi in this study, and these enzymes hydrolyses wide range of carbohydrate and non-carbohydrate substrates. Putative melanin, siderophore, ent-kaurene, and lycopene biosynthesis gene clusters are predicted, and these gene clusters denote that UM 591 are capable of protecting itself from the UV and chemical stresses, allowing it to adapt to different environment. Putative sterigmatocystin, HC-toxin, cercosporin, and gliotoxin biosynthesis gene cluster are predicted. This finding have highlighted the necrotrophic and invasive nature of UM 591. PMID:28149676

  6. Genomic insight into pathogenicity of dematiaceous fungus Corynespora cassiicola

    Directory of Open Access Journals (Sweden)

    Hong Keat Looi

    2017-01-01

    Full Text Available Corynespora cassiicola is a common plant pathogen that causes leaf spot disease in a broad range of crop, and it heavily affect rubber trees in Malaysia (Hsueh, 2011; Nghia et al., 2008. The isolation of UM 591 from a patient’s contact lens indicates the pathogenic potential of this dematiaceous fungus in human. However, the underlying factors that contribute to the opportunistic cross-infection have not been fully studied. We employed genome sequencing and gene homology annotations in attempt to identify these factors in UM 591 using data obtained from publicly available bioinformatics databases. The assembly size of UM 591 genome is 41.8 Mbp, and a total of 13,531 (≥99 bp genes have been predicted. UM 591 is enriched with genes that encode for glycoside hydrolases, carbohydrate esterases, auxiliary activity enzymes and cell wall degrading enzymes. Virulent genes comprising of CAZymes, peptidases, and hypervirulence-associated cutinases were found to be present in the fungal genome. Comparative analysis result shows that UM 591 possesses higher number of carbohydrate esterases family 10 (CE10 CAZymes compared to other species of fungi in this study, and these enzymes hydrolyses wide range of carbohydrate and non-carbohydrate substrates. Putative melanin, siderophore, ent-kaurene, and lycopene biosynthesis gene clusters are predicted, and these gene clusters denote that UM 591 are capable of protecting itself from the UV and chemical stresses, allowing it to adapt to different environment. Putative sterigmatocystin, HC-toxin, cercosporin, and gliotoxin biosynthesis gene cluster are predicted. This finding have highlighted the necrotrophic and invasive nature of UM 591.

  7. Does methyl salicylate, a component of herbivore-induced plant odour, promote sporulation of the mite-pathogenic fungus Neozygites tanajoae?

    Science.gov (United States)

    Hountondji, Fabien C C; Hanna, Rachid; Sabelis, Maurice W

    2006-01-01

    Blends of volatile chemicals emanating from cassava leaves infested by the cassava green mite were found to promote conidiation of Neozygites tanajoae, an entomopathogenic fungus specific to this mite. Methyl salicylate (MeSA) is one compound frequently present in blends of herbivore-induced plant volatiles (HIPV) as well as that of mite-infested cassava. Here, we investigated the effect of methyl salicylate in its pure form on the production of pre-infective spores (conidia), and the germination of these spores into infective spores (capilliconidia), by a Brazilian isolate and a Beninese isolate of N. tanajoae. Mummified mites previously infected by the fungal isolates were screened under optimal abiotic conditions for sporulation inside tightly closed boxes with or without methyl salicylate diffusing from a capillary tube. Production of conidia was consistently higher (37%) when the Beninese isolate was exposed to MeSA than when not exposed to it (305.5 +/- 52.62 and 223.2 +/- 38.13 conidia per mummy with and without MeSA, respectively). MeSA, however, did not promote conidia production by the Brazilian isolate (387.4 +/- 44.74 and 415.8 +/- 57.95 conidia per mummy with and without MeSA, respectively). Germination of the conidia into capilliconidia was not affected by MeSA for either isolate (0.2%, 252.6 +/- 31.80 vs. 253.0 +/- 36.65 for the Beninese isolate and 4.2%, 268.5 +/- 37.90 vs. 280.2 +/- 29.43 for the Brazilian isolate). The effects of MeSA on the production of conidia were similar to those obtained under exposure to the complete blends of HIPV for the case of the Beninese isolate, but dissimilar (no promoting effect of MeSA) for the case of the Brazilian isolate. This shows that MeSA, being one compound out of many HIPV, can be a factor promoting sporulation of N. tanajoae, but it may not be the only factor as its effect varies with the fungal isolate under study.

  8. Tracking the footsteps of an invasive plant pathogen: Intercontinental phylogeographic structure of the white-pine-blister-rust fungus, Cronartium ribicola

    Science.gov (United States)

    Bryce A. Richardson; Mee-Sook Kim; Ned B. Klopfenstein; Yuko Ota; Kwan Soo Woo; Richard C. Hamelin

    2009-01-01

    Presently, little is known about the worldwide genetic structure, diversity, or evolutionary relationships of the white-pineblister-rust fungus, Cronartium ribicola. A collaborative international effort is underway to determine the phylogeographic relationships among Asian, European, and North American sources of C. ribicola and...

  9. Decomposition of Plant Debris by the Nematophagous Fungus ARF

    OpenAIRE

    Wang, Kening; Riggs, R. D.; Crippen, Devany

    2004-01-01

    In the study of the biological control of plant-parasitic nematodes, knowledge of the saprophytic ability of a nematophagous fungus is necessary to understand its establishment and survival in the soil. The objectives of this study were (i) to determine if the nematophagous fungus ARF (Arkansas Fungus) shows differential use of plant residues; and (ii) to determine if ARF still existed in the soil of a field in which ARF was found originally and in which the population level of Heterodera gly...

  10. Investigating the biology of plant infection by the rice blast fungus Magnaporthe oryzae.

    Science.gov (United States)

    Martin-Urdiroz, Magdalena; Oses-Ruiz, Miriam; Ryder, Lauren S; Talbot, Nicholas J

    2016-05-01

    The rice blast fungus, Magnaporthe oryzae, is responsible for the most serious disease of rice and is a continuing threat to ensuring global food security. The fungus has also, however, emerged as a model experimental organism for understanding plant infection processes by pathogenic fungi. This is largely due to its amenability to both classical and molecular genetics, coupled with the efforts of a very large international research community. This review, which is based on a plenary presentation at the 28th Fungal Genetics Conference in Asilomar, California in March 2015, describes recent progress in understanding how M. oryzae uses specialised cell called appressoria to bring about plant infection and the underlying biology of this developmental process. We also review how the fungus is then able to proliferate within rice tissue, deploying effector proteins to facilitate its spread by suppressing plant immunity and promoting growth and development of the fungus.

  11. Plant Pathogenic Fungi and Oomycetes

    NARCIS (Netherlands)

    Wit, de P.J.G.M.

    2015-01-01

    Fungi and Oomycetes are notorious plant pathogens and use similar strategies to infect plants. The majority of plants, however, is not infected by pathogens as they recognize pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors that mediate PAMP-triggered immunity (PTI) ,

  12. Plant Pathogenic Fungi and Oomycetes

    NARCIS (Netherlands)

    Wit, de P.J.G.M.

    2015-01-01

    Fungi and Oomycetes are notorious plant pathogens and use similar strategies to infect plants. The majority of plants, however, is not infected by pathogens as they recognize pathogen-associated molecular patterns (PAMPs) by pattern recognition receptors that mediate PAMP-triggered immunity (PTI) ,

  13. Draft Genome Sequence of Rhizobium sp. Strain TBD182, an Antagonist of the Plant-Pathogenic Fungus Fusarium oxysporum, Isolated from a Novel Hydroponics System Using Organic Fertilizer.

    Science.gov (United States)

    Iida, Yuichiro; Fujiwara, Kazuki; Someya, Nobutaka; Shinohara, Makoto

    2017-03-16

    Rhizobium sp. strain TBD182, isolated from a novel hydroponics system, is an antagonistic bacterium that inhibits the mycelial growth of Fusarium oxysporum but does not eliminate the pathogen. We report the draft genome sequence of TBD182, which may contribute to elucidation of the molecular mechanisms of its fungistatic activity. Copyright © 2017 Iida et al.

  14. Draft Genome Sequence of Rhizobium sp. Strain TBD182, an Antagonist of the Plant-Pathogenic Fungus Fusarium oxysporum, Isolated from a Novel Hydroponics System Using Organic Fertilizer

    Science.gov (United States)

    Fujiwara, Kazuki; Someya, Nobutaka; Shinohara, Makoto

    2017-01-01

    ABSTRACT Rhizobium sp. strain TBD182, isolated from a novel hydroponics system, is an antagonistic bacterium that inhibits the mycelial growth of Fusarium oxysporum but does not eliminate the pathogen. We report the draft genome sequence of TBD182, which may contribute to elucidation of the molecular mechanisms of its fungistatic activity. PMID:28302768

  15. Treatment of a clinically relevant plant-pathogenic fungus with an agricultural azole causes cross-resistance to medical azoles and potentiates caspofungin efficacy.

    Science.gov (United States)

    Serfling, Albrecht; Wohlrab, Johannes; Deising, Holger B

    2007-10-01

    Azoles are extensively applied in agriculture and medicine, and a relationship between the development of azole resistance in agriculture and the development of azole resistance in clinical practice may exist. The maize pathogen Colletotrichum graminicola, causing cutaneous mycosis and keratitis, has been used to investigate the acquisition of resistance to an agricultural azole and the resulting cross-resistance to various medical antifungal agents. Azole-adapted strains were less sensitive to all azoles tested but showed increased sensitivity to caspofungin, amphotericin B, and nystatin. Viability staining and infection assays with excised human skin confirmed these data.

  16. Analysis of proteins in the extracellular matrix of the plant pathogenic fungus Bipolaris sorokiniana using 2-D gel electrophoresis and MS/MS.

    Science.gov (United States)

    Apoga, D; Ek, B; Tunlid, A

    2001-04-13

    A method was developed for isolating and sequencing proteins present in the extracellular matrix (ECM) of germlings and hyphae of filamentous fungi. Surface proteins of the cereal pathogen Bipolaris sorokiniana were labelled with a membrane impermeable biotinylating agent and extracted using a glycine-HCl buffer. Extracted proteins were purified by affinity binding to streptavidin-conjugated magnetic beads or by two-dimensional gel electrophoresis. Four of the biotinylated proteins from the ECM of B. sorokiniana were isolated, in gel digested with trypsin and partly sequenced by tandem mass spectrometry. No significant sequence similarities to proteins in databases were obtained.

  17. Novel secretory protein Ss-Caf1 of the plant-pathogenic fungus Sclerotinia sclerotiorum is required for host penetration and normal sclerotial development.

    Science.gov (United States)

    Xiao, Xueqiong; Xie, Jiatao; Cheng, Jiasen; Li, Guoqing; Yi, Xianhong; Jiang, Daohong; Fu, Yanping

    2014-01-01

    To decipher the mechanism of pathogenicity in Sclerotinia sclerotiorum, a pathogenicity-defective mutant, Sunf-MT6, was isolated from a T-DNA insertional library. Sunf-MT6 could not form compound appressorium and failed to induce lesions on leaves of rapeseed though it could produce more oxalic acid than the wild-type strain. However, it could enter into host tissues via wounds and cause typical necrotic lesions. Furthermore, Sunf-MT6 produced fewer but larger sclerotia than the wild-type strain Sunf-M. A gene, named Ss-caf1, was disrupted by T-DNA insertion in Sunf-MT6. Gene complementation and knockdown experiments confirmed that the disruption of Ss-caf1 was responsible for the phenotypic changes of Sunf-MT6. Ss-caf1 encodes a secretory protein with a putative Ca(2+)-binding EF-hand motif. High expression levels of Ss-caf1 were observed at an early stage of compound appressorium formation and in immature sclerotia. Expression of Ss-caf1 without signal peptides in Nicotiana benthamiana via Tobacco rattle virus-based vectors elicited cell death. These results suggest that Ss-caf1 plays an important role in compound appressorium formation and sclerotial development of S. sclerotiorum. In addition, Ss-Caf1 has the potential to interact with certain host proteins or unknown substances in host cells, resulting in subsequent host cell death.

  18. Candicidin-producing Streptomyces support leaf-cutting ants to protect their fungus garden against the pathogenic fungus Escovopsis

    OpenAIRE

    Haeder, Susanne; Wirth, Rainer; Herz, Hubert; Spiteller, Dieter

    2009-01-01

    Leaf-cutting ants such as Acromyrmex octospinosus live in obligate symbiosis with fungi of the genus Leucoagaricus, which they grow with harvested leaf material. The symbiotic fungi, in turn, serve as a major food source for the ants. This mutualistic relation is disturbed by the specialized pathogenic fungus Escovopsis sp., which can overcome Leucoagaricus sp. and thus destroy the ant colony. Microbial symbionts of leaf-cutting ants have been suggested to protect the fungus garden against Es...

  19. The SOD2 gene, encoding a manganese-type superoxide dismutase, is up-regulated during conidiogenesis in the plant-pathogenic fungus Colletotrichum graminicola.

    Science.gov (United States)

    Fang, G-C; Hanau, R M; Vaillancourt, L J

    2002-07-01

    The SOD2 gene, encoding a manganese-type superoxide dismutase (MnSOD), was identified from Colletotrichum graminicola among a collection of cDNAs representing genes that are up-regulated during conidiogenesis. The SOD2 gene consists of a 797-bp open reading frame that is interrupted by three introns and is predicted to encode a polypeptide of 208 amino acids. All conserved residues of the MnSOD protein family, including four consensus metal binding domains, are present in the predicted SOD2 protein. However, the predicted protein does not appear to contain a signal peptide that would target it to the mitochondria. Northern hybridizations revealed that expression of the approximately 900-bp SOD2 transcript is closely associated with differentiation of both oval and falcate conidia. Southern analysis indicated that there is only a single copy of the gene. SOD2 disruption strains were morphologically and pathogenically indistinguishable from wild-type strains. The dispensability of the MnSOD enzyme may be due to the activities of two other SOD enzymes, a highly expressed iron-type superoxide dismutase and a much less abundant copper/zinc type, that were also detected in C. graminicola.

  20. QTL mapping of temperature sensitivity reveals candidate genes for thermal adaptation and growth morphology in the plant pathogenic fungus Zymoseptoria tritici.

    Science.gov (United States)

    Lendenmann, M H; Croll, D; Palma-Guerrero, J; Stewart, E L; McDonald, B A

    2016-04-01

    Different thermal environments impose strong, differential selection on populations, leading to local adaptation, but the genetic basis of thermal adaptation is poorly understood. We used quantitative trait locus (QTL) mapping in the fungal wheat pathogen Zymoseptoria tritici to study the genetic architecture of thermal adaptation and identify candidate genes. Four wild-type strains originating from the same thermal environment were crossed to generate two mapping populations with 263 (cross 1) and 261 (cross 2) progeny. Restriction site-associated DNA sequencing was used to genotype 9745 (cross 1) and 7333 (cross 2) single-nucleotide polymorphism markers segregating within the mapping population. Temperature sensitivity was assessed using digital image analysis of colonies growing at two different temperatures. We identified four QTLs for temperature sensitivity, with unique QTLs found in each cross. One QTL had a logarithm of odds score >11 and contained only six candidate genes, including PBS2, encoding a mitogen-activated protein kinase kinase associated with low temperature tolerance in Saccharomyces cerevisiae. This and other QTLs showed evidence for pleiotropy among growth rate, melanization and growth morphology, suggesting that many traits can be correlated with thermal adaptation in fungi. Higher temperatures were highly correlated with a shift to filamentous growth among the progeny in both crosses. We show that thermal adaptation has a complex genetic architecture, with natural populations of Z. tritici harboring significant genetic variation for this trait. We conclude that Z. tritici populations have the potential to adapt rapidly to climate change and expand into new climatic zones.

  1. Protein profiling of the dimorphic, pathogenic fungus, Penicillium marneffei

    Directory of Open Access Journals (Sweden)

    Rundle William T

    2008-06-01

    Full Text Available Abstract Background Penicillium marneffei is a pathogenic fungus that afflicts immunocompromised individuals having lived or traveled in Southeast Asia. This species is unique in that it is the only dimorphic member of the genus. Dimorphism results from a process, termed phase transition, which is regulated by temperature of incubation. At room temperature, the fungus grows filamentously (mould phase, but at body temperature (37°C, a uninucleate yeast form develops that reproduces by fission. Formation of the yeast phase appears to be a requisite for pathogenicity. To date, no genes have been identified in P. marneffei that strictly induce mould-to-yeast phase conversion. In an effort to help identify potential gene products associated with morphogenesis, protein profiles were generated from the yeast and mould phases of P. marneffei. Results Whole cell proteins from the early stages of mould and yeast development in P. marneffei were resolved by two-dimensional gel electrophoresis. Selected proteins were recovered and sequenced by capillary-liquid chromatography-nanospray tandem mass spectrometry. Putative identifications were derived by searching available databases for homologous fungal sequences. Proteins found common to both mould and yeast phases included the signal transduction proteins cyclophilin and a RACK1-like ortholog, as well as those related to general metabolism, energy production, and protection from oxygen radicals. Many of the mould-specific proteins identified possessed similar functions. By comparison, proteins exhibiting increased expression during development of the parasitic yeast phase comprised those involved in heat-shock responses, general metabolism, and cell-wall biosynthesis, as well as a small GTPase that regulates nuclear membrane transport and mitotic processes in fungi. The cognate gene encoding the latter protein, designated RanA, was subsequently cloned and characterized. The P. marneffei RanA protein

  2. DHN melanin biosynthesis in the plant pathogenic fungus Botrytis cinerea is based on two developmentally regulated key enzyme (PKS)-encoding genes.

    Science.gov (United States)

    Schumacher, Julia

    2016-02-01

    Botrytis cinerea is the causal agent of gray mold disease in various plant species and produces grayish macroconidia and/or black sclerotia at the end of the infection cycle. It has been suggested that the pigmentation is due to the accumulation of 1,8-dihydroxynaphthalene (DHN) melanin. To unravel its basis and regulation, the putative melanogenic and regulatory genes were identified and functionally characterized. Unlike other DHN melanin-producing fungi, B. cinerea and other Leotiomycetes contain two key enzyme (PKS)-encoding enzymes. Bcpks12 and bcpks13 are developmentally regulated and are required for melanogenesis in sclerotia and conidia respectively. BcYGH1 converts the BcPKS13 product and contributes thereby to conidial melanogenesis. In contrast, enzymes acting downstream in conversion of the PKS products (BcBRN2, BcSCD1 and BcBRN1) are required for both, sclerotial and conidial melanogenesis, suggesting that DHN melanogenesis in B. cinerea follows a non-linear pathway that is rather unusual for secondary metabolic pathways. Regulation of the melanogenic genes involves three pathway-specific transcription factors (TFs) that are clustered with bcpks12 or bcpks13 and other developmental regulators such as light-responsive TFs. Melanogenic genes are dispensable in vegetative mycelia for proper growth and virulence. However, DHN melanin is considered to contribute to the longevity of the reproduction structures.

  3. Degradation of the plant defence hormone salicylic acid by the biotrophic fungus Ustilago maydis.

    Science.gov (United States)

    Rabe, Franziska; Ajami-Rashidi, Ziba; Doehlemann, Gunther; Kahmann, Regine; Djamei, Armin

    2013-07-01

    Salicylic acid (SA) is a key plant defence hormone which plays an important role in local and systemic defence responses against biotrophic pathogens like the smut fungus Ustilago maydis. Here we identified Shy1, a cytoplasmic U. maydis salicylate hydroxylase which has orthologues in the closely related smuts Ustilago hordei and Sporisorium reilianum. shy1 is transcriptionally induced during the biotrophic stages of development but not required for virulence during seedling infection. Shy1 activity is needed for growth on plates with SA as a sole carbon source. The trigger for shy1 transcriptional induction is SA, suggesting the possibility of a SA sensing mechanism in this fungus.

  4. Draft genome of the fungus-growing termite pathogenic fungus Ophiocordyceps bispora (Ophiocordycipitaceae, Hypocreales, Ascomycota).

    Science.gov (United States)

    Conlon, Benjamin H; Mitchell, Jannette; de Beer, Z Wilhelm; Carøe, Christian; Gilbert, M Thomas P; Eilenberg, Jørgen; Poulsen, Michael; de Fine Licht, Henrik H

    2017-04-01

    This article documents the public availability of genome sequence data and assembled contigs representing the partial draft genome of Ophiocordyceps bispora. As one of the few known pathogens of fungus-farming termites, a draft genome of O. bispora represents the opportunity to further the understanding of disease and resistance in these complex termite societies. With the ongoing attempts to resolve the taxonomy of the Hypocralaean family, more genetic data will also help to shed light on the phylogenetic relationship between sexual and asexual life stages. Next generation sequence data is available from the European Nucleotide Archive (ENA) under accession PRJEB13655; run numbers: ERR1368522, ERR1368523, and ERR1368524. Genome assembly available from ENA under accession numbers: FKNF01000001-FKNF01000302. Gene prediction available as protein fasta, nucleotide fasta and GFF file from Mendeley Data with accession doi:10.17632/r99fd6g3s4.2 (http://dx.doi.org/10.17632/r99fd6g3s4.2).

  5. Draft genome of the fungus-growing termite pathogenic fungus Ophiocordyceps bispora (Ophiocordycipitaceae, Hypocreales, Ascomycota

    Directory of Open Access Journals (Sweden)

    Benjamin H. Conlon

    2017-04-01

    Full Text Available This article documents the public availability of genome sequence data and assembled contigs representing the partial draft genome of Ophiocordyceps bispora. As one of the few known pathogens of fungus-farming termites, a draft genome of O. bispora represents the opportunity to further the understanding of disease and resistance in these complex termite societies. With the ongoing attempts to resolve the taxonomy of the Hypocralaean family, more genetic data will also help to shed light on the phylogenetic relationship between sexual and asexual life stages. Next generation sequence data is available from the European Nucleotide Archive (ENA under accession PRJEB13655; run numbers: ERR1368522, ERR1368523, and ERR1368524. Genome assembly available from ENA under accession numbers: FKNF01000001–FKNF01000302. Gene prediction available as protein fasta, nucleotide fasta and GFF file from Mendeley Data with accession doi:10.17632/r99fd6g3s4.2 (http://dx.doi.org/10.17632/r99fd6g3s4.2.

  6. Role of mannitol metabolism in the pathogenicity of the necrotrophic fungus Alternaria brassicicola

    Directory of Open Access Journals (Sweden)

    Benoit eCalmes

    2013-05-01

    Full Text Available In this study, the physiological functions of fungal mannitol metabolism in the pathogenicity and protection against environmental stresses were investigated in the necrotrophic fungus Alternaria brassicicola. Mannitol metabolism was examined during infection of Brassica oleracea leaves by sequential HPLC quantification of the major soluble carbohydrates and expression analysis of genes encoding two proteins of mannitol metabolism, i.e. a mannitol dehydrogenase (AbMdh, and a mannitol-1-phosphate dehydrogenase (AbMpd. Knockout mutants deficient for AbMdh or AbMpd and a double mutant lacking both enzyme activities were constructed. Their capacity to cope with various oxidative and drought stresses and their pathogenic behaviour were evaluated. Metabolic and gene expression profiling indicated an increase in mannitol production during plant infection. Depending on the mutants, distinct pathogenic processes, such as leaf and silique colonization, sporulation, survival on seeds, were impaired by comparison to the wild-type. This pathogenic alteration could be partly explained by the differential susceptibilities of mutants to oxidative and drought stresses. These results highlight the importance of mannitol metabolism with respect to the ability of A. brassicicola to efficiently accomplish key steps of its pathogenic life cycle.

  7. A role for antioxidants in acclimation of marine derived pathogenic fungus (NIOCC 1) to salt stress.

    Science.gov (United States)

    Ravindran, Chinnarajan; Varatharajan, Govindaswamy R; Rajasabapathy, Raju; Vijayakanth, S; Kumar, Alagu Harish; Meena, Ram M

    2012-09-01

    Salinity tolerance a key factor helps in understanding the ionic homeostasis in general, which is a fundamental cellular phenomenon in all living cells. Here, a marine derived pathogenic fungus was examined for its adaptation under salt stress using antioxidant properties. The aqueous extracts of halophilic fungus exhibited different levels of antioxidant activity in all the in vitro tests such as α,α-diphenyl-β-picrylhydrazyl (DPPH(·)), Hydroxyl Radical Scavenging Assay (HRSA), Metal chelating assay and β-carotene-linoleic acid model system. The antioxidant capacity of marine fungus exposed to high salt condition showed an increase in activity. In addition, the production of intra and extracellular antioxidant enzymes of the fungus at various salt stresses were analyzed and discussed for their possible role in the stress mechanism. The marine derived fungus was identified as Phialosimplex genus, which is associated with infections in dogs. Thus the present study elucidates that the scavenging activity is one of the protective mechanisms developed in the fungus to avoid the deleterious effect of salt stress. In addition, the study also helps in understanding how the pathogenic fungus tackles the oxidative burst i.e. hypersensitivity reaction performed by host to kill the pathogens.

  8. 454-pyrosequencing of Coffea arabica leaves infected by the rust fungus Hemileia vastatrix reveals in planta-expressed pathogen-secreted proteins and plant functions in a late compatible plant-rust interaction

    OpenAIRE

    Fernandez, Diana; Tisserant, E.; Talhinhas, P.; Azinheira, H; Vieira, A.; Petitot, Anne-Sophie; Loureiro, A.; Poulain, J.; Da Silva, C; Silva, M. D. C.; Duplessis, S.

    2012-01-01

    Coffee (Coffea arabica L.), one of the key export and cash crops in tropical and subtropical countries, suffers severe losses from the rust fungus Hemileia vastatrix. The transcriptome of H. vastatrix was analysed during a compatible interaction with coffee to obtain an exhaustive repertoire of the genes expressed during infection and to identify potential effector genes. Large-scale sequencing (454-GS-FLEX Titanium) of mixed coffee and rust cDNAs obtained from 21-day rust-infected leaves gen...

  9. Specificity in the interaction between an epibiotic clavicipitalean fungus and its convolvulaceous host in a fungus/plant symbiotum

    Science.gov (United States)

    Steiner, Ulrike; Hellwig, Sabine

    2008-01-01

    Ipomoea asarifolia and Turbina corymbosa (Convolvulaceae) are associated with epibiotic clavicipitalean fungi responsible for the presence of ergoline alkaloids in these plants. Experimentally generated plants devoid of these fungi were inoculated with different epibiotic and endophytic fungi resulting in a necrotic or commensal situation. A symbiotum of host plant and its respective fungus was best established by integration of the fungus into the morphological differentiation of the host plant. This led us to suppose that secretory glands on the leaf surface of the host plant may play an essential role in ergoline alkaloid biosynthesis which takes place in the epibiotic fungus. PMID:19704834

  10. Ecological niche of plant pathogens

    Directory of Open Access Journals (Sweden)

    Ecaterina Fodor

    2011-02-01

    Full Text Available Disease ecology is a new approach to the understanding of the spread and dynamics of pathogens in natural and man-made environments. Defining and describing the ecological niche of the pathogens is one of the major tasks for ecological theory, as well as for practitioners preoccupied with the control and forecasting of established and emerging diseases. Niche theory has been periodically revised, not including in an explicit way the pathogens. However, many progresses have been achieved in niche modeling of disease spread, but few attempts were made to construct a theoretical frame for the ecological niche of pathogens. The paper is a review of the knowledge accumulated during last decades in the niche theory of pathogens and proposes an ecological approach in research. It quest for new control methods in what concerns forest plant pathogens, with a special emphasis on fungi like organisms of the genus Phytophthora. Species of Phytophthora are the most successful plant pathogens of the moment, affecting forest and agricultural systems worldwide, many of them being invasive alien organisms in many ecosystems. The hyperspace of their ecological niche is defined by hosts, environment and human interference, as main axes. To select most important variables within the hyperspace, is important for the understanding of the complex role of pathogens in the ecosystems as well as for control programs. Biotic relationships within ecosystem of host-pathogen couple are depicted by ecological network and specific metrics attached to this. The star shaped network is characterized by few high degree nodes, by short path lengths and relatively low connectivity, premises for a rapid disturbance spread.

  11. Ecological niche of plant pathogens

    Directory of Open Access Journals (Sweden)

    Ecaterina Fodor

    2011-06-01

    Full Text Available Disease ecology is a new approach to the understanding of the spread and dynamics of pathogens in natural and man-made environments. Defining and describing the ecological niche of the pathogens is one of the major tasks for ecological theory, as well as for practitioners preoccupied with the control and forecasting of established and emerging diseases. Niche theory has been periodically revised, not including in an explicit way the pathogens. However, many progresses have been achieved in niche modeling of disease spread, but few attempts were made to construct a theoretical frame for the ecological niche of pathogens. The paper is a review of the knowledge accumulated during last decades in the niche theory of pathogens and proposes an ecological approach in research. It quest for new control methods in what concerns forest plant pathogens, with a special emphasis on fungi like organisms of the genus Phytophthora. Species of Phytophthora are the most successful plant pathogens of the moment, affecting forest and agricultural systems worldwide, many of them being invasive alien organisms in many ecosystems. The hyperspace of their ecological niche is defined by hosts, environment and human interference, as main axes. To select most important variables within the hyperspace, is important the understanding of the complex role of pathogens in the ecosystems as well as for control programs. Biotic relationships within ecosystem of host-pathogen couple are depicted by ecological network and specific metrics attached to this. The star shaped network is characterized by few high degree nodes, by short path lengths and relatively low connectivity, premises for a rapid disturbance spread. 

  12. Endophytic fungus-vascular plant-insect interactions.

    Science.gov (United States)

    Raman, A; Wheatley, W; Popay, A

    2012-06-01

    Insect association with fungi has a long history. Theories dealing with the evolution of insect herbivory indicate that insects used microbes including fungi as their principal food materials before flowering plants evolved. Subtlety and the level of intricacy in the interactions between insects and fungi indicate symbiosis as the predominant ecological pattern. The nature of the symbiotic interaction that occurs between two organisms (the insect and the fungus), may be either mutualistic or parasitic, or between these two extremes. However, the triangular relationship involving three organisms, viz., an insect, a fungus, and a vascular plant is a relationship that is more complicated than what can be described as either mutualism or parasitism, and may represent facets of both. Recent research has revealed such a complex relationship in the vertically transmitted type-I endophytes living within agriculturally important grasses and the pestiferous insects that attack them. The intricacy of the association depends on the endophytic fungus-grass association and the insect present. Secondary compounds produced in the endophytic fungus-grass association can provide grasses with resistance to herbivores resulting in mutualistic relationship between the fungus and the plant that has negative consequences for herbivorous insects. The horizontally transmitted nongrass type-II endophytes are far less well studied and as such their ecological roles are not fully understood. This forum article explores the intricacy of dependence in such complex triangular relationships drawing from well-established examples from the fungi that live as endophytes in vascular plants and how they impact on the biology and evolution of free-living as well as concealed (e.g., gall-inducing, gall-inhabiting) insects. Recent developments with the inoculation of strains of type-I fungal endophytes into grasses and their commercialization are discussed, along with the possible roles the endophytic

  13. Decomposition of Plant Debris by the Nematophagous Fungus ARF.

    Science.gov (United States)

    Wang, Kening; Riggs, R D; Crippen, Devany

    2004-09-01

    In the study of the biological control of plant-parasitic nematodes, knowledge of the saprophytic ability of a nematophagous fungus is necessary to understand its establishment and survival in the soil. The objectives of this study were (i) to determine if the nematophagous fungus ARF (Arkansas Fungus) shows differential use of plant residues; and (ii) to determine if ARF still existed in the soil of a field in which ARF was found originally and in which the population level of Heterodera glycines had remained very low, despite 15 years of continuous, susceptible soybean. Laboratory studies of the decomposition of wheat straw or soybean root by ARF were conducted in two separate experiments, using a CO collection apparatus, where CO-free air was passed through sterilized cotton to remove the microorganisms in the air and then was passed over the samples, and evolved CO was trapped by KOH. Milligrams of C as CO was used to calculate the percentage decomposition of the plant debris by ARF. Data indicated ARF decomposed 11.7% of total organic carbon of the wheat straw and 20.1% of the soybean roots in 6 weeks. In the field soil study, 21 soil samples were taken randomly from the field. Only 3 months after the infestation of the soil with H. glycines, the percentage of parasitized eggs of H. glycines reached 64 +/- 19%, and ARF was isolated from most parasitized eggs of H. glycines. Research results indicated ARF could use plant residues to survive.

  14. Expressed sequences tags of the anther smut fungus, Microbotryum violaceum, identify mating and pathogenicity genes

    Directory of Open Access Journals (Sweden)

    Devier Benjamin

    2007-08-01

    Full Text Available Abstract Background The basidiomycete fungus Microbotryum violaceum is responsible for the anther-smut disease in many plants of the Caryophyllaceae family and is a model in genetics and evolutionary biology. Infection is initiated by dikaryotic hyphae produced after the conjugation of two haploid sporidia of opposite mating type. This study describes M. violaceum ESTs corresponding to nuclear genes expressed during conjugation and early hyphal production. Results A normalized cDNA library generated 24,128 sequences, which were assembled into 7,765 unique genes; 25.2% of them displayed significant similarity to annotated proteins from other organisms, 74.3% a weak similarity to the same set of known proteins, and 0.5% were orphans. We identified putative pheromone receptors and genes that in other fungi are involved in the mating process. We also identified many sequences similar to genes known to be involved in pathogenicity in other fungi. The M. violaceum EST database, MICROBASE, is available on the Web and provides access to the sequences, assembled contigs, annotations and programs to compare similarities against MICROBASE. Conclusion This study provides a basis for cloning the mating type locus, for further investigation of pathogenicity genes in the anther smut fungi, and for comparative genomics.

  15. Effector candidates in the secretome of Piriformospora indica, a ubiquitous plant-associated fungus

    Directory of Open Access Journals (Sweden)

    Maryam eRafiqi

    2013-07-01

    Full Text Available One of the emerging systems in plant-microbe interaction is the study of proteins, referred to as effectors, secreted by microbes in order to modulate host cells function and structure and to promote microbial growth on plant tissue. Current knowledge on fungal effectors derives mainly from biotrophic and hemibiotrophic plant fungal pathogens that have a limited host range. Here, we focus on effectors of Piriformospora indica, a soil borne endophyte forming intimate associations with roots of a wide range of plant species. Complete genome sequencing provides an opportunity to investigate the role of effectors during the interaction of this mutualistic fungus with plants. We describe in silico analyses to predict effectors of P. indica and we explore effector features considered here to mine a high priority protein list for functional analysis.

  16. Bacterium induces cryptic meroterpenoid pathway in the pathogenic fungus Aspergillus fumigatus.

    Science.gov (United States)

    König, Claudia C; Scherlach, Kirstin; Schroeckh, Volker; Horn, Fabian; Nietzsche, Sandor; Brakhage, Axel A; Hertweck, Christian

    2013-05-27

    Stimulating encounter: The intimate, physical interaction between the soil-derived bacterium Streptomyces rapamycinicus and the human pathogenic fungus Aspergillus fumigatus led to the activation of an otherwise silent polyketide synthase (PKS) gene cluster coding for an unusual prenylated polyphenol (fumicycline A). The meroterpenoid pathway is regulated by a pathway-specific activator gene as well as by epigenetic factors.

  17. Genetic aspects of ash dieback caused by the pathogenic fungus Chalara fraxinea on Fraxinus excelsior

    DEFF Research Database (Denmark)

    McKinney, Lea Vig

    ). This thesis comprises five papers that aim to contribute to the knowledge on the interaction between the pathogen and its host and the inherent natural resistance found within the host species. Paper I reviews the current literature on the aetiology of the fungus, the epidemic and its consequences...

  18. Fungal keratitis due to Schizophyllum commune: an emerging pathogenic fungus.

    Science.gov (United States)

    Reddy, Ashok Kumar; Ashok, Rangaiahgari; Majety, Madhavi; Chitta, Megharaj; Narayen, Nitesh

    2016-07-12

    Fungal keratitis due to Schizophyllum commune is very rare. In this study, we report the clinical and microbiological profile of five patients with fungal keratitis due to S. commune. Direct microscopic examination of corneal scrapings from all five patients showed septate branching hyaline fungal filaments. Similarly, in all five patients Sabouraud dextrose agar (SDA) plates inoculated with corneal scrapings showed white, cottony colonies on the second day of incubation. Lactophenol cotton blue stained wet preparation of 7-day-old colonies on SDA revealed clamp connections and no spores. The fungus was identified by its characteristic clamp connections, fan-shaped bracket fruiting body with pinkish-grey longitudinally split-radiating gills. The phenotypic identification of one of the five isolates further conformed by ITS sequencing. Treatment outcome was available for two of the five patients; in these two patients, the keratitis resolved with topical natamycin. © 2016 Blackwell Verlag GmbH.

  19. Bioactive secondary metabolites from Nigrospora sp. LLGLM003, an endophytic fungus of the medicinal plant Moringa oleifera Lam.

    Science.gov (United States)

    Zhao, J H; Zhang, Y L; Wang, L W; Wang, J Y; Zhang, C L

    2012-05-01

    An endophytic fungus was isolated from the root of the medicinal plant Moringa oleifera Lam. Based on analyzing the rDNA sequence, the fungus was identified as Nigrospora sp. This is the first report of the isolation of endophytic Nigrospora from M. oleifera. By bioassay-guided fractionation, four antifungal secondary metabolites were isolated from liquid cultures of the fungus Nigrospora sp. LLGLM003, and their chemical structures were determined to be griseofulvin (1), dechlorogriseofulvin (2), 8-dihydroramulosin (3) and mellein (4) on the basis of spectroscopic analyses. Compound 2, 3 and 4 were isolated from Nigrospora sp. for the first time. In vitro antifungal assay showed that griseofulvin displayed clear inhibition of the growth of 8 plant pathogenic fungi. Dechlorogriseofulvin and mellein exhibited only weak antifungal activities, whereas 8-dihydroramulosin displayed no antifungal activities.

  20. Inducing Fungus-Resistance into Plants through Biotechnology

    OpenAIRE

    Wani, Shabir Hussain

    2010-01-01

    Plant diseases are caused by a variety of plant pathogens including fungi, and their management requires the use of techniques like transgenic technology, molecular biology, and genetics. There have been attempts to use gene technology as an alternative method to protect plants from microbial diseases, in addition to the development of novel agrochemicals and the conventional breeding of resistant cultivars. Various genes have been introduced into plants, and the enhanced resistance against f...

  1. Health monitoring of plants by their emitted volatiles: A temporary increase in the concentration of nethyl salicylate after pathogen inoculation of tomato plants at greenhouse scale

    NARCIS (Netherlands)

    Jansen, R.M.C.; Hofstee, J.W.; Verstappen, F.W.A.; Bouwmeester, H.J.; Posthumus, M.A.; Henten, van E.J.

    2011-01-01

    This paper describes a method to alert growers of the presence of a pathogen infection in their greenhouse based on the detection of pathogen-induced emissions of volatile organic compounds (VOCs) from plants. Greenhouse-grown plants were inoculated with spores of a fungus to learn more about this c

  2. Azole drug import into the pathogenic fungus Aspergillus fumigatus.

    Science.gov (United States)

    Esquivel, Brooke D; Smith, Adam R; Zavrel, Martin; White, Theodore C

    2015-01-01

    The fungal pathogen Aspergillus fumigatus causes serious illness and often death when it invades tissues, especially in immunocompromised individuals. The azole class of drugs is the most commonly prescribed treatment for many fungal infections and acts on the ergosterol biosynthesis pathway. One common mechanism of acquired azole drug resistance in fungi is the prevention of drug accumulation to toxic levels in the cell. While drug efflux is a well-known resistance strategy, reduced azole import would be another strategy to maintain low intracellular azole levels. Recently, azole uptake in Candida albicans and other yeasts was analyzed using [(3)H]fluconazole. Defective drug import was suggested to be a potential mechanism of drug resistance in several pathogenic fungi, including Cryptococcus neoformans, Candida krusei, and Saccharomyces cerevisiae. We have adapted and developed an assay to measure azole accumulation in A. fumigatus using radioactively labeled azole drugs, based on previous work done with C. albicans. We used this assay to study the differences in azole uptake in A. fumigatus isolates under a variety of drug treatment conditions, with different morphologies and with a select mutant strain with deficiencies in the sterol uptake and biosynthesis pathway. We conclude that azole drugs are specifically selected and imported into the fungal cell by a pH- and ATP-independent facilitated diffusion mechanism, not by passive diffusion. This method of drug transport is likely to be conserved across most fungal species.

  3. Pathogenicity of entomopathogenic fungus Metarhizium anisopliae (Deuteromycetes) to Ixodes scapularis (Acari: Ixodidae)

    Science.gov (United States)

    Zhioua, E.; Browning, M.; Johnson, P.W.; Ginsberg, H.S.; LeBrun, R.A.

    1997-01-01

    The entomopathogenic fungus Metarhizium anisopliae is highly pathogenic to the black-legged tick, Ixodes scapularis. Spore concentrations of 108/ml for engorged larvae and 107/ml for engorged females resulted in 100% tick mortality, 2 wk post-infection. The LC50 value for engorged larvae (concentration to kill 50% of ticks) was 107 spores/ml. Metarhizium anisopliae shows considerable potential as a microbial control agent for the management of Ixodes scapularis.

  4. A role for antioxidants in acclimation of marine derived pathogenic fungus (NIOCC 1) to salt stress

    Digital Repository Service at National Institute of Oceanography (India)

    Ravindran, C.; Varatharajan, G.R.; Rajasabapathy, R.; Vijayakanth, S.; HarishKumar, A.; Meena, R.M.

    to almost saturated NaCl solutions [5, 6]. Thus, some fungal species like Debaryomyces hansenii, Hortaea werneckii, and Wallemia ichthyophaga have been isolated globally from natural hypersaline environments [7]. Halophilic micro-organisms also have... fungus tackles the oxidative burst i.e. hypersensitivity reaction performed by host to kill the pathogens. 2. Materials and Methods 2.1. Chemicals Sodium bicarbonate, Folins–Ciocalteu reagent, Gallic acid, Sodium nitrite (NaNO 2 ), Aluminium...

  5. Plants versus pathogens: an evolutionary arms race.

    Science.gov (United States)

    Anderson, Jonathan P; Gleason, Cynthia A; Foley, Rhonda C; Thrall, Peter H; Burdon, Jeremy B; Singh, Karam B

    2010-05-20

    The analysis of plant-pathogen interactions is a rapidly moving research field and one that is very important for productive agricultural systems. The focus of this review is on the evolution of plant defence responses and the coevolution of their pathogens, primarily from a molecular-genetic perspective. It explores the evolution of the major types of plant defence responses including pathogen associated molecular patterns and effector triggered immunity as well as the forces driving pathogen evolution, such as the mechanisms by which pathogen lineages and species evolve. Advances in our understanding of plant defence signalling, stomatal regulation, R gene-effector interactions and host specific toxins are used to highlight recent insights into the coevolutionary arms race between pathogens and plants. Finally, the review considers the intriguing question of how plants have evolved the ability to distinguish friends such as rhizobia and mycorrhiza from their many foes.

  6. Sporothrix globosa, a pathogenic fungus with widespread geographical distribution.

    Science.gov (United States)

    Madrid, Hugo; Cano, Josep; Gené, Josepa; Bonifaz, Alexandro; Toriello, Conchita; Guarro, Josep

    2009-09-30

    Sporothrix globosa, reported from the USA, Europe, and Asia, is a recently described pathogenic species morphologically similar to Sporothrix schenckii. In this study, the phylogenetic affinities of 32 clinical and environmental isolates morphologically identified as S. schenckii, from Mexico, Guatemala, and Colombia, were assessed by cladistic analysis of partial sequences of the calmodulin gene using the maximum parsimony and neighbor-joining methods. The study revealed that one out of 25 isolates from Mexico (4%), one out of three isolates from Guatemala (33.3%), and two out of four isolates from Colombia (50%) belonged to S. globosa, while the other isolates belonged to S. schenckii sensu stricto. This is the first record of S. globosa from Mexico, and Central and South America.

  7. Genomic islands in the pathogenic filamentous fungus Aspergillus fumigatus.

    Directory of Open Access Journals (Sweden)

    Natalie D Fedorova

    2008-04-01

    Full Text Available We present the genome sequences of a new clinical isolate of the important human pathogen, Aspergillus fumigatus, A1163, and two closely related but rarely pathogenic species, Neosartorya fischeri NRRL181 and Aspergillus clavatus NRRL1. Comparative genomic analysis of A1163 with the recently sequenced A. fumigatus isolate Af293 has identified core, variable and up to 2% unique genes in each genome. While the core genes are 99.8% identical at the nucleotide level, identity for variable genes can be as low 40%. The most divergent loci appear to contain heterokaryon incompatibility (het genes associated with fungal programmed cell death such as developmental regulator rosA. Cross-species comparison has revealed that 8.5%, 13.5% and 12.6%, respectively, of A. fumigatus, N. fischeri and A. clavatus genes are species-specific. These genes are significantly smaller in size than core genes, contain fewer exons and exhibit a subtelomeric bias. Most of them cluster together in 13 chromosomal islands, which are enriched for pseudogenes, transposons and other repetitive elements. At least 20% of A. fumigatus-specific genes appear to be functional and involved in carbohydrate and chitin catabolism, transport, detoxification, secondary metabolism and other functions that may facilitate the adaptation to heterogeneous environments such as soil or a mammalian host. Contrary to what was suggested previously, their origin cannot be attributed to horizontal gene transfer (HGT, but instead is likely to involve duplication, diversification and differential gene loss (DDL. The role of duplication in the origin of lineage-specific genes is further underlined by the discovery of genomic islands that seem to function as designated "gene dumps" and, perhaps, simultaneously, as "gene factories".

  8. Plant and pathogen nutrient acquisition strategies

    OpenAIRE

    Fatima, Urooj; Senthil-Kumar, Muthappa

    2015-01-01

    Nutrients are indispensable elements required for the growth of all living organisms including plants and pathogens. Phyllosphere, rhizosphere, apoplast, phloem, xylem, and cell organelles are the nutrient niches in plants that are the target of bacterial pathogens. Depending upon nutrients availability, the pathogen adapts various acquisition strategies and inhabits the specific niche. In this review, we discuss the nutrient composition of different niches in plants, the mechanisms involved ...

  9. Diplopyrone, a new phytotoxic tetrahydropyranpyran-2-one produced by Diplodia mutila, a fungus pathogen of cork oak.

    Science.gov (United States)

    Evidente, Antonio; Maddau, Lucia; Spanu, Emanuela; Franceschini, Antonio; Lazzaroni, Silvia; Motta, Andrea

    2003-02-01

    A new phytotoxic monosubstituted tetrahydropyranpyran-2-one, named diplopyrone (1), was isolated from the liquid culture filtrates of Diplodia mutila, a plant pathogenic fungus causing a form of canker disease of cork oak (Quercus suber). Diplopyrone was characterized, using spectroscopic and chemical methods, as 6-[(1S)-1-hydroxyethyl]-2,4a,6,8a-tetrahydropyran[3,2-b]pyran-2-one. The absolute stereochemistry of the chiral secondary hydroxylated carbon (C-9), determined by application of Mosher's method, proved to be S. Diplopyrone assayed at a 0.01-0.1 mg/mL concentration range caused necrosis and wilting on cork oak cuttings. On a nonhost plant, tomato, diplopyrone caused brown discoloration or stewing on the stem.

  10. Pathogenic fungus Batrachochytrium dendrobatidis in marbled water frog Telmatobius marmoratus: first record from Lake Titicaca, Bolivia.

    Science.gov (United States)

    Cossel, John; Lindquist, Erik; Craig, Heather; Luthman, Kyle

    2014-11-13

    The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has been associated with amphibian declines worldwide but has not been well-studied among Critically Endangered amphibian species in Bolivia. We sampled free-living marbled water frogs Telmatobius marmoratus (Anura: Leptodactylidae) from Isla del Sol, Bolivia, for Bd using skin swabs and quantitative polymerase chain reactions. We detected Bd on 44% of T. marmoratus sampled. This is the first record of Bd in amphibians from waters associated with Lake Titicaca, Bolivia. These results further confirm the presence of Bd in Bolivia and substantiate the potential threat of this pathogen to the Critically Endangered, sympatric Titicaca water frog T. culeus and other Andean amphibians.

  11. 火棘抑菌内生真菌的筛选与拮抗植物病原菌作用研究%Screening of Pyracantha fortuneana Endophytic Fungus and Function Examination of Antagonism to Plant Pathogenic Fungi

    Institute of Scientific and Technical Information of China (English)

    田小曼; 陈阿敏

    2012-01-01

    采用常规分离方法从火棘的茎、叶、果实中分离得到15株内生真菌,以小麦根腐病菌、小麦赤霉病菌、番茄早疫病菌等9种病原真菌作靶标菌,筛选出了一株具有较高抑菌活性的菌株-J4,采用形态学观察和ITS序列测定相结合的方法对J4进行鉴定.结果表明,J4菌株为子囊菌亚门间座壳属(Dia porthe)真菌.%Fifteen endophytic fungi were screened from the stems, leaves, and fruits of Pyracantha fortuneana. The antifungal activities of the fungi to 9 plant pathogenic fungi (including Bipolaris sorokiniana , Gibberella zeae ,and Alternaria solani and so on) were selected. One strain, J4 with high antifungal activity was screened and obtained. Morphological observations and ITS sequence of strain J4 were conducted. The results showed that the strain belonged to ascomycetes Diaporthe genus.

  12. Programmed cell cycle arrest is required for infection of corn plants by the fungus Ustilago maydis.

    Science.gov (United States)

    Castanheira, Sónia; Mielnichuk, Natalia; Pérez-Martín, José

    2014-12-01

    Ustilago maydis is a plant pathogen that requires a specific structure called infective filament to penetrate the plant tissue. Although able to grow, this filament is cell cycle arrested on the plant surface. This cell cycle arrest is released once the filament penetrates the plant tissue. The reasons and mechanisms for this cell cycle arrest are unknown. Here, we have tried to address these questions. We reached three conclusions from our studies. First, the observed cell cycle arrest is the result of the cooperation of at least two distinct mechanisms: one involving the activation of the DNA damage response (DDR) cascade; and the other relying on the transcriptional downregulation of Hsl1, a kinase that modulates the G2/M transition. Second, a sustained cell cycle arrest during the infective filament step is necessary for the virulence in U. maydis, as a strain unable to arrest the cell cycle was severely impaired in its ability to infect corn plants. Third, production of the appressorium, a structure required for plant penetration, is incompatible with an active cell cycle. The inability to infect plants by strains defective in cell cycle arrest seems to be caused by their failure to induce the appressorium formation process. In summary, our findings uncover genetic circuits to arrest the cell cycle during the growth of this fungus on the plant surface, thus allowing the penetration into plant tissue.

  13. Meiosis Drives Extraordinary Genome Plasticity in the Haploid Fungal Plant Pathogen Mycosphaerella Graminicola

    Science.gov (United States)

    Meiosis in the plant-pathogenic fungus Mycosphaerella graminicola results in eight ascospores due to a mitotic division following the two meiotic divisions. The transient diploid phase allows for recombination among homologous chromosomes. However, some chromosomes of M. graminicola lack homologs an...

  14. Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi

    Directory of Open Access Journals (Sweden)

    Bergstrom Gary C

    2011-02-01

    Full Text Available Abstract Background The discovery and development of novel plant cell wall degrading enzymes is a key step towards more efficient depolymerization of polysaccharides to fermentable sugars for the production of liquid transportation biofuels and other bioproducts. The industrial fungus Trichoderma reesei is known to be highly cellulolytic and is a major industrial microbial source for commercial cellulases, xylanases and other cell wall degrading enzymes. However, enzyme-prospecting research continues to identify opportunities to enhance the activity of T. reesei enzyme preparations by supplementing with enzymatic diversity from other microbes. The goal of this study was to evaluate the enzymatic potential of a broad range of plant pathogenic and non-pathogenic fungi for their ability to degrade plant biomass and isolated polysaccharides. Results Large-scale screening identified a range of hydrolytic activities among 348 unique isolates representing 156 species of plant pathogenic and non-pathogenic fungi. Hierarchical clustering was used to identify groups of species with similar hydrolytic profiles. Among moderately and highly active species, plant pathogenic species were found to be more active than non-pathogens on six of eight substrates tested, with no significant difference seen on the other two substrates. Among the pathogenic fungi, greater hydrolysis was seen when they were tested on biomass and hemicellulose derived from their host plants (commelinoid monocot or dicot. Although T. reesei has a hydrolytic profile that is highly active on cellulose and pretreated biomass, it was less active than some natural isolates of fungi when tested on xylans and untreated biomass. Conclusions Several highly active isolates of plant pathogenic fungi were identified, particularly when tested on xylans and untreated biomass. There were statistically significant preferences for biomass type reflecting the monocot or dicot host preference of the

  15. Epigenetic control of effectors in plant pathogens

    Directory of Open Access Journals (Sweden)

    Mark eGijzen

    2014-11-01

    Full Text Available Plant pathogens display impressive versatility in adapting to host immune systems. Pathogen effector proteins facilitate disease but can become avirulence (Avr factors when the host acquires discrete recognition capabilities that trigger immunity. The mechanisms that lead to changes to pathogen Avr factors that enable escape from host immunity are diverse, and include epigenetic switches that allow for reuse or recycling of effectors. This perspective outlines possibilities of how epigenetic control of Avr effector gene expression may have arisen and persisted in plant pathogens, and how it presents special problems for diagnosis and detection of specific pathogen strains or pathotypes.

  16. Development of a greenhouse-based inoculation protocol for the fungus Colletotrichum cereale pathogenic to annual bluegrass (Poa annua

    Directory of Open Access Journals (Sweden)

    Lisa A. Beirn

    2015-08-01

    Full Text Available The fungus Colletotrichum cereale incites anthracnose disease on Poa annua (annual bluegrass turfgrass. Anthracnose disease is geographically widespread throughout the world and highly destructive to cool-season turfgrasses, with infections by C. cereale resulting in extensive turf loss. Comprehensive research aimed at controlling turfgrass anthracnose has been performed in the field, but knowledge of the causal organism and its basic biology is still needed. In particular, the lack of a reliable greenhouse-based inoculation protocol performed under controlled environmental conditions is an obstacle to the study of C. cereale and anthracnose disease. Our objective was to develop a consistent and reproducible inoculation protocol for the two major genetic lineages of C. cereale. By adapting previously successful field-based protocols and combining with components of existing inoculation procedures, the method we developed consistently produced C. cereale infection on two susceptible P. annua biotypes. Approximately 7 to 10 days post-inoculation, plants exhibited chlorosis and thinning consistent with anthracnose disease symptomology. Morphological inspection of inoculated plants revealed visual signs of the fungus (appressoria and acervuli, although acervuli were not always present. After stringent surface sterilization of inoculated host tissue, C. cereale was consistently re-isolated from symptomatic tissue. Real-time PCR detection analysis based on the Apn2 marker confirmed the presence of the pathogen in host tissue, with both lineages of C. cereale detected from all inoculated plants. When a humidifier was not used, no infection developed for any biotypes or fungal isolates tested. The inoculation protocol described here marks significant progress for in planta studies of C. cereale, and will enable scientifically reproducible investigations of the biology, infectivity and lifestyle of this important grass pathogen.

  17. Genome sequences of 12 isolates of the EU1 lineage of Phytophthora ramorum, a fungus-like pathogen that causes extensive damage and mortality to a wide range of trees and other plants.

    Science.gov (United States)

    Turner, Judith; O'Neill, Paul; Grant, Murray; Mumford, Rick A; Thwaites, Richard; Studholme, David J

    2017-06-01

    Here we present genome sequences for twelve isolates of the invasive pathogen Phytophthora ramorum EU1. The assembled genome sequences and raw sequence data are available via BioProject accession number PRJNA177509. These data will be useful in developing molecular tools for specific detection and identification of this pathogen.

  18. Antibody-based resistance to plant pathogens.

    Science.gov (United States)

    Schillberg, S; Zimmermann, S; Zhang, M Y; Fischer, R

    2001-01-01

    Plant diseases are a major threat to the world food supply, as up to 15% of production is lost to pathogens. In the past, disease control and the generation of resistant plant lines protected against viral, bacterial or fungal pathogens, was achieved using conventional breeding based on crossings, mutant screenings and backcrossing. Many approaches in this field have failed or the resistance obtained has been rapidly broken by the pathogens. Recent advances in molecular biotechnology have made it possible to obtain and to modify genes that are useful for generating disease resistant crops. Several strategies, including expression of pathogen-derived sequences or anti-pathogenic agents, have been developed to engineer improved pathogen resistance in transgenic plants. Antibody-based resistance is a novel strategy for generating transgenic plants resistant to pathogens. Decades ago it was shown that polyclonal and monoclonal antibodies can neutralize viruses, bacteria and selected fungi. This approach has been improved recently by the development of recombinant antibodies (rAbs). Crop resistance can be engineered by the expression of pathogen-specific antibodies, antibody fragments or antibody fusion proteins. The advantages of this approach are that rAbs can be engineered against almost any target molecule, and it has been demonstrated that expression of functional pathogen-specific rAbs in plants confers effective pathogen protection. The efficacy of antibody-based resistance was first shown for plant viruses and its application to other plant pathogens is becoming more established. However, successful use of antibodies to generate plant pathogen resistance relies on appropriate target selection, careful antibody design, efficient antibody expression, stability and targeting to appropriate cellular compartments.

  19. Efficient Transmission of an Introduced Pathogen Via an Ancient Insect-Fungus Association

    Science.gov (United States)

    Battisti, A.; Roques, A.; Colombari, F.; Frigimelica, G.; Guido, M.

    In Cupressus sempervirens the association between seed insects and tree pathogens has resulted in optimal exploitation of the cones. A fungus-infected cone can be inhabited by the nymphs of a true seed bug (Orsillus maculatus), the adults of which may carry a heavy spore load at emergence. Cones are infected when eggs are laid within the cone, most frequently via the emergence holes of a seed wasp (Megastigmus wachtli). This symbiotic association evolved with the nonaggressive fungus Pestalotiopsis funerea within the natural range of the cypress. When the aggressive cypress canker disease (Seiridium cardinale) was introduced into Europe, it was transmitted by O. maculatus to cones usually colonized by Pestalotiopsis funerea, with disastrous consequences for the regeneration and survival of C. sempervirens in the entire Mediterranean area.

  20. Trade-offs in an ant-plant-fungus mutualism.

    Science.gov (United States)

    Orivel, Jérôme; Malé, Pierre-Jean; Lauth, Jérémie; Roux, Olivier; Petitclerc, Frédéric; Dejean, Alain; Leroy, Céline

    2017-03-15

    Species engaged in multiple, simultaneous mutualisms are subject to trade-offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners' traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host-plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species. © 2017 The Author(s).

  1. New Bergamotane Sesquiterpenoids from the Plant Endophytic Fungus Paraconiothyrium brasiliense

    Directory of Open Access Journals (Sweden)

    Zhe Guo

    2015-08-01

    Full Text Available Brasilamides K-N (1–4, four new bergamotane sesquiterpenoids; with 4-oxatricyclo (3.3.1.0 2,7nonane (1and 9-oxatricyclo(4.3.0.0 4,7nonane (2–4 skeletons; were isolated from the scale-up fermentation cultures of the plant endophytic fungus Paraconiothynium brasiliense Verkley. The previously identified sesquiterpenoids brasilamides A and C (5 and 6 were also reisolated in the current work. The structures of 1–4 were elucidated primarily by interpretation of NMR spectroscopic data. The absolute configurations of 1–3 were deduced by analogy to the co-isolated metabolites 5 and 6; whereas that of C-12 in 4 was assigned using the modified Mosher method. The cytotoxicity of all compounds against a panel of eight human tumor cell lines were assayed.

  2. Social transfer of pathogenic fungus promotes active immunisation in ant colonies.

    Directory of Open Access Journals (Sweden)

    Matthias Konrad

    Full Text Available Due to the omnipresent risk of epidemics, insect societies have evolved sophisticated disease defences at the individual and colony level. An intriguing yet little understood phenomenon is that social contact to pathogen-exposed individuals reduces susceptibility of previously naive nestmates to this pathogen. We tested whether such social immunisation in Lasius ants against the entomopathogenic fungus Metarhizium anisopliae is based on active upregulation of the immune system of nestmates following contact to an infectious individual or passive protection via transfer of immune effectors among group members--that is, active versus passive immunisation. We found no evidence for involvement of passive immunisation via transfer of antimicrobials among colony members. Instead, intensive allogrooming behaviour between naive and pathogen-exposed ants before fungal conidia firmly attached to their cuticle suggested passage of the pathogen from the exposed individuals to their nestmates. By tracing fluorescence-labelled conidia we indeed detected frequent pathogen transfer to the nestmates, where they caused low-level infections as revealed by growth of small numbers of fungal colony forming units from their dissected body content. These infections rarely led to death, but instead promoted an enhanced ability to inhibit fungal growth and an active upregulation of immune genes involved in antifungal defences (defensin and prophenoloxidase, PPO. Contrarily, there was no upregulation of the gene cathepsin L, which is associated with antibacterial and antiviral defences, and we found no increased antibacterial activity of nestmates of fungus-exposed ants. This indicates that social immunisation after fungal exposure is specific, similar to recent findings for individual-level immune priming in invertebrates. Epidemiological modeling further suggests that active social immunisation is adaptive, as it leads to faster elimination of the disease and lower

  3. The biotechnological use and potential of plant pathogenic smut fungi.

    Science.gov (United States)

    Feldbrügge, Michael; Kellner, Ronny; Schipper, Kerstin

    2013-04-01

    Plant pathogens of the family Ustilaginaceae parasitise mainly on grasses and cause smut disease. Among the best characterised members of this family are the covered smut fungus Ustilago hordei colonising barley and oat as well as the head smut Sporisorium reilianum and the corn smut Ustilago maydis, both infecting maize. Over the past years, U. maydis in particular has matured into a model system for diverse topics like plant-pathogen interaction, cellular transport processes or DNA repair. Consequently, a broad set of genetic, molecular and system biological methods has been established. This set currently serves as a strong foundation to improve existing and establish novel biotechnological applications. Here, we review four promising aspects covering different fields of applied science: (1) synthesis of secondary metabolites produced at fermenter level. (2) Lipases and other hydrolytic enzymes with potential roles in biocatalytic processes. (3) Degradation of ligno-cellulosic plant materials for biomass conversion. (4) Protein expression based on unconventional secretion, a novel approach inspired by basic research on mRNA transport. Thus, plant pathogenic Ustilaginaceae offer a great potential for future biotechnological applications by combining basic research and applied science.

  4. [Features of interaction bacterial strains Micrococcus luteus LBK1 from plants varieties/hybrids cucumber and sweet pepper and with fungus Fusarium oxysporum Scelecht].

    Science.gov (United States)

    Parfeniuk, A; Sterlikova, O; Beznosko, I; Krut', V

    2014-01-01

    The article presents the results of studying the impact of bacterial strain M. luteus LBK1, stimulating the growth and development of plant varieties/hybrids of cucumber and sweet pepper on the intensity of sporulation of the fungus F. oxysporum Scelecht--fusariose rot pathogen.

  5. Effect of wheat roots infected with the pathogenic fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp.

    Science.gov (United States)

    Barret, Matthieu; Frey-Klett, Pascale; Guillerm-Erckelboudt, Anne-Yvonne; Boutin, Morgane; Guernec, Gregory; Sarniguet, Alain

    2009-12-01

    Traits contributing to the competence of biocontrol bacteria to colonize plant roots are often induced in the rhizosphere in response to plant components. These interactions have been studied using the two partners in gnotobiotic systems. However, in nature, beneficial or pathogenic fungi often colonize roots. Influence of these plant-fungus interactions on bacterial behavior remains to be investigated. Here, we have examined the influence of colonization of wheat roots by the take-all fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. Bacteria were inoculated onto healthy, early G. graminis var. tritici-colonized and necrotic roots and transcriptomes were compared by shotgun DNA microarray. Pf29Arp decreased disease severity when inoculated before the onset of necrosis. Necrotic roots exerted a broader effect on gene expression compared with early G. graminis var. tritici-colonized and healthy roots. A gene encoding a putative type VI secretion system effector was only induced in necrotic conditions. A common pool of Pf29Arp genes differentially expressed on G. graminis var. tritici-colonized roots was related to carbon metabolism and oxidative stress, with a highest fold-change with necrosis. Overall, the data showed that the association of the pathogenic fungus with the roots strongly altered Pf29Arp adaptation with differences between early and late G. graminis var. tritici infection steps.

  6. Two Rab5 Homologs Are Essential for the Development and Pathogenicity of the Rice Blast Fungus Magnaporthe oryzae

    Directory of Open Access Journals (Sweden)

    Cheng D. Yang

    2017-05-01

    Full Text Available The rice blast fungus, Magnaporthe oryzae, infects many economically important cereal crops, particularly rice. It has emerged as an important model organism for studying the growth, development, and pathogenesis of filamentous fungi. RabGTPases are important molecular switches in regulation of intracellular membrane trafficking in all eukaryotes. MoRab5A and MoRab5B are Rab5 homologs in M. oryzae, but their functions in the fungal development and pathogenicity are unknown. In this study, we have employed a genetic approach and demonstrated that both MoRab5A and MoRab5B are crucial for vegetative growth and development, conidiogenesis, melanin synthesis, vacuole fusion, endocytosis, sexual reproduction, and plant pathogenesis in M. oryzae. Moreover, both MoRab5A and MoRab5B show similar localization in hyphae and conidia. To further investigate possible functional redundancy between MoRab5A and MoRab5B, we overexpressed MoRAB5A and MoRAB5B, respectively, in MoRab5B:RNAi and MoRab5A:RNAi strains, but neither could rescue each other’s defects caused by the RNAi. Taken together, we conclude that both MoRab5A and MoRab5B are necessary for the development and pathogenesis of the rice blast fungus, while they may function independently.

  7. Genome sequencing and comparative genomics reveal a repertoire of putative pathogenicity genes in chilli anthracnose fungus Colletotrichum truncatum.

    Science.gov (United States)

    Rao, Soumya; Nandineni, Madhusudan R

    2017-01-01

    Colletotrichum truncatum, a major fungal phytopathogen, causes the anthracnose disease on an economically important spice crop chilli (Capsicum annuum), resulting in huge economic losses in tropical and sub-tropical countries. It follows a subcuticular intramural infection strategy on chilli with a short, asymptomatic, endophytic phase, which contrasts with the intracellular hemibiotrophic lifestyle adopted by most of the Colletotrichum species. However, little is known about the molecular determinants and the mechanism of pathogenicity in this fungus. A high quality whole genome sequence and gene annotation based on transcriptome data of an Indian isolate of C. truncatum from chilli has been obtained. Analysis of the genome sequence revealed a rich repertoire of pathogenicity genes in C. truncatum encoding secreted proteins, effectors, plant cell wall degrading enzymes, secondary metabolism associated proteins, with potential roles in the host-specific infection strategy, placing it next only to the Fusarium species. The size of genome assembly, number of predicted genes and some of the functional categories were similar to other sequenced Colletotrichum species. The comparative genomic analyses with other species and related fungi identified some unique genes and certain highly expanded gene families of CAZymes, proteases and secondary metabolism associated genes in the genome of C. truncatum. The draft genome assembly and functional annotation of potential pathogenicity genes of C. truncatum provide an important genomic resource for understanding the biology and lifestyle of this important phytopathogen and will pave the way for designing efficient disease control regimens.

  8. Antibody-mediated resistance against plant pathogens.

    Science.gov (United States)

    Safarnejad, Mohammad Reza; Jouzani, Gholamreza Salehi; Tabatabaei, Meisam; Tabatabaie, Meisam; Twyman, Richard M; Schillberg, Stefan

    2011-01-01

    Plant diseases have a significant impact on the yield and quality of crops. Many strategies have been developed to combat plant diseases, including the transfer of resistance genes to crops by conventional breeding. However, resistance genes can only be introgressed from sexually-compatible species, so breeders need alternative measures to introduce resistance traits from more distant sources. In this context, genetic engineering provides an opportunity to exploit diverse and novel forms of resistance, e.g. the use of recombinant antibodies targeting plant pathogens. Native antibodies, as a part of the vertebrate adaptive immune system, can bind to foreign antigens and eliminate them from the body. The ectopic expression of antibodies in plants can also interfere with pathogen activity to confer disease resistance. With sufficient knowledge of the pathogen life cycle, it is possible to counter any disease by designing expression constructs so that pathogen-specific antibodies accumulate at high levels in appropriate sub-cellular compartments. Although first developed to tackle plant viruses and still used predominantly for this purpose, antibodies have been targeted against a diverse range of pathogens as well as proteins involved in plant-pathogen interactions. Here we comprehensively review the development and implementation of antibody-mediated disease resistance in plants.

  9. Chytrid fungus acts as a generalist pathogen infecting species-rich amphibian families in Brazilian rainforests.

    Science.gov (United States)

    Valencia-Aguilar, Anyelet; Ruano-Fajardo, Gustavo; Lambertini, Carolina; da Silva Leite, Domingos; Toledo, Luís Felipe; Mott, Tamí

    2015-05-11

    The fungus Batrachochytrium dendrobatidis (Bd) is among the main causes of declines in amphibian populations. This fungus is considered a generalist pathogen because it infects several species and spreads rapidly in the wild. To date, Bd has been detected in more than 100 anuran species in Brazil, mostly in the southern portion of the Atlantic forest. Here, we report survey data from some poorly explored regions; these data considerably extend current information on the distribution of Bd in the northern Atlantic forest region. In addition, we tested the hypothesis that Bd is a generalist pathogen in this biome. We also report the first positive record for Bd in an anuran caught in the wild in Amazonia. In total, we screened 90 individuals (from 27 species), of which 39 individuals (from 22 species) were Bd-positive. All samples collected in Bahia (2 individuals), Pernambuco (3 individuals), Pará (1 individual), and Minas Gerais (1 individual) showed positive results for Bd. We found a positive correlation between anuran richness per family and the number of infected species in the Atlantic forest, supporting previous observations that Bd lacks strong host specificity; of 38% of the anuran species in the Atlantic forest that were tested for Bd infection, 25% showed positive results. The results of our study exemplify the pandemic and widespread nature of Bd infection in amphibians.

  10. Draft genome sequence of Karnal bunt pathogen (Tilletia indica) of wheat provides insights into the pathogenic mechanisms of quarantined fungus

    Science.gov (United States)

    Singh, Manoj; Pandey, Dinesh; Saharan, M. S.; Marla, Soma S.

    2017-01-01

    Karnal bunt disease in wheat is caused by hemibiotrophic fungus, Tilletia indica that has been placed as quarantine pest in more than 70 countries. Despite its economic importance, little knowledge about the molecular components of fungal pathogenesis is known. In this study, first time the genome sequence of T. indica has been deciphered for unraveling the effectors’ functions of molecular pathogenesis of Karnal bunt disease. The T. indica genome was sequenced employing hybrid approach of PacBio Single Molecule Real Time (SMRT) and Illumina HiSEQ 2000 sequencing platforms. The genome was assembled into 10,957 contigs (N50 contig length 3 kb) with total size of 26.7 Mb and GC content of 53.99%. The number of predicted putative genes were 11,535, which were annotated with Gene Ontology databases. Functional annotation of Karnal bunt pathogen genome and classification of identified effectors into protein families revealed interesting functions related to pathogenesis. Search for effectors’ genes using pathogen host interaction database identified 135 genes. The T. indica genome sequence and putative genes involved in molecular pathogenesis would further help in devising novel and effective disease management strategies including development of resistant wheat genotypes, novel biomarkers for pathogen detection and new targets for fungicide development. PMID:28152050

  11. Peniamidienone and penidilamine, plant growth regulators produced by the fungus Penicillium sp. No. 13.

    Science.gov (United States)

    Kimura, Y; Mizuno, T; Kawano, T; Okada, K; Shimada, A

    2000-04-01

    Peniamidienone and penidilamine were isolated from cultures of the fungus Penicillium sp. No. 13 as new plant growth regulators and their structures were established by NMR spectroscopic studies. Peniamidienone showed weak inhibition of lettuce seedling growth.

  12. The hidden habit of the entomopathogenic fungus Beauveria bassiana: first demonstration of vertical plant transmission.

    Directory of Open Access Journals (Sweden)

    Enrique Quesada-Moraga

    Full Text Available Beauveria bassiana strain 04/01-Tip, obtained from a larva of the opium poppy stem gall wasp Iraella luteipes (Hymenoptera; Cynipidae, endophytically colonizes opium poppy (Papaver somniferum L. plants and protects them against this pest. The goal of this study was to monitor the dynamics of endophytic colonization of opium poppy by B. bassiana after the fungus was applied to the seed and to ascertain whether the fungus is transmitted vertically via seeds. Using a species-specific nested PCR protocol and DNA extracted from surface-sterilised leaf pieces or seeds of B. bassiana-inoculated opium poppy plants, the fungus was detected within the plant beginning at the growth stage of rosette building and them throughout the entire plant growth cycle (about 120-140 days after sowing. The fungus was also detected in seeds from 50% of the capsules sampled. Seeds that showed positive amplification for B. bassiana were planted in sterile soil and the endophyte was again detected in more than 42% of the plants sampled during all plant growth stages. Beauveria bassiana was transmitted to seeds in 25% of the plants from the second generation that formed a mature capsule. These results demonstrate for the first time the vertical transmission of an entomopathogenic fungus from endophytically colonised maternal plants. This information is crucial to better understand the ecological role of entomopathogenic fungi as plant endophytes and may allow development of a sustainable and cost effective strategy for I. luteipes management in P. somniferum.

  13. The hidden habit of the entomopathogenic fungus Beauveria bassiana: first demonstration of vertical plant transmission.

    Science.gov (United States)

    Quesada-Moraga, Enrique; López-Díaz, Cristina; Landa, Blanca Beatriz

    2014-01-01

    Beauveria bassiana strain 04/01-Tip, obtained from a larva of the opium poppy stem gall wasp Iraella luteipes (Hymenoptera; Cynipidae), endophytically colonizes opium poppy (Papaver somniferum L.) plants and protects them against this pest. The goal of this study was to monitor the dynamics of endophytic colonization of opium poppy by B. bassiana after the fungus was applied to the seed and to ascertain whether the fungus is transmitted vertically via seeds. Using a species-specific nested PCR protocol and DNA extracted from surface-sterilised leaf pieces or seeds of B. bassiana-inoculated opium poppy plants, the fungus was detected within the plant beginning at the growth stage of rosette building and them throughout the entire plant growth cycle (about 120-140 days after sowing). The fungus was also detected in seeds from 50% of the capsules sampled. Seeds that showed positive amplification for B. bassiana were planted in sterile soil and the endophyte was again detected in more than 42% of the plants sampled during all plant growth stages. Beauveria bassiana was transmitted to seeds in 25% of the plants from the second generation that formed a mature capsule. These results demonstrate for the first time the vertical transmission of an entomopathogenic fungus from endophytically colonised maternal plants. This information is crucial to better understand the ecological role of entomopathogenic fungi as plant endophytes and may allow development of a sustainable and cost effective strategy for I. luteipes management in P. somniferum.

  14. Plant and pathogen nutrient acquisition strategies

    Directory of Open Access Journals (Sweden)

    Urooj eFatima

    2015-09-01

    Full Text Available Nutrients are indispensable elements required for the growth of all living organisms including plants and pathogens. Phyllosphere, rhizosphere, apoplast, phloem, xylem and cell organelles are the nutrient niches in plants that are the target of bacterial pathogens. Depending upon nutrients availability, the pathogen adapts various acquisition strategies and inhabits the specific niche. In this review, we discuss the nutrient composition of different niches in plants, the mechanisms involved in the recognition of nutrient niche and the sophisticated strategies used by the bacterial pathogens for acquiring nutrients. We provide insight into various nutrient acquisition strategies used by necrotrophic, biotrophic and hemi-biotrophic bacteria. Specifically we discuss both modulation of bacterial machinery and manipulation of host machinery. In addition, we highlight the current status of our understanding about the nutrient acquisition strategies used by bacterial pathogens, namely targeting the sugar transporters that are dedicated for the plant’s growth and development. Bacterial strategies for altering the plant cell membrane permeability to enhance the release of nutrients are also enumerated along with in-depth analysis of molecular mechanisms behind these strategies. The information presented in this review will be useful to understand the plant-pathogen interaction in nutrient perspective.

  15. Microbial Forensics and Plant Pathogens

    Science.gov (United States)

    New awareness of the vulnerability of a nation's agricultural infrastructure to the intentional introduction of pathogens or pests has led to the enhancement of programs for prevention and preparedness. A necessary component of a balanced bio-security plan is the capability to determine whether an ...

  16. DNA mutations mediate microevolution between host-adapted forms of the pathogenic fungus Cryptococcus neoformans.

    Directory of Open Access Journals (Sweden)

    Denise A Magditch

    Full Text Available The disease cryptococcosis, caused by the fungus Cryptococcus neoformans, is acquired directly from environmental exposure rather than transmitted person-to-person. One explanation for the pathogenicity of this species is that interactions with environmental predators select for virulence. However, co-incubation of C. neoformans with amoeba can cause a "switch" from the normal yeast morphology to a pseudohyphal form, enabling fungi to survive exposure to amoeba, yet conversely reducing virulence in mammalian models of cryptococcosis. Like other human pathogenic fungi, C. neoformans is capable of microevolutionary changes that influence the biology of the organism and outcome of the host-pathogen interaction. A yeast-pseudohyphal phenotypic switch also happens under in vitro conditions. Here, we demonstrate that this morphological switch, rather than being under epigenetic control, is controlled by DNA mutation since all pseudohyphal strains bear mutations within genes encoding components of the RAM pathway. High rates of isolation of pseudohyphal strains can be explained by the physical size of RAM pathway genes and a hypermutator phenotype of the strain used in phenotypic switching studies. Reversion to wild type yeast morphology in vitro or within a mammalian host can occur through different mechanisms, with one being counter-acting mutations. Infection of mice with RAM mutants reveals several outcomes: clearance of the infection, asymptomatic maintenance of the strains, or reversion to wild type forms and progression of disease. These findings demonstrate a key role of mutation events in microevolution to modulate the ability of a fungal pathogen to cause disease.

  17. Molecular inversion probe: a new tool for highly specific detection of plant pathogens.

    Directory of Open Access Journals (Sweden)

    Han Yih Lau

    Full Text Available Highly specific detection methods, capable of reliably identifying plant pathogens are crucial in plant disease management strategies to reduce losses in agriculture by preventing the spread of diseases. We describe a novel molecular inversion probe (MIP assay that can be potentially developed into a robust multiplex platform to detect and identify plant pathogens. A MIP has been designed for the plant pathogenic fungus Fusarium oxysporum f.sp. conglutinans and the proof of concept for the efficiency of this technology is provided. We demonstrate that this methodology can detect as little as 2.5 ng of pathogen DNA and is highly specific, being able to accurately differentiate Fusarium oxysporum f.sp. conglutinans from other fungal pathogens such as Botrytis cinerea and even pathogens of the same species such as Fusarium oxysporum f.sp. lycopersici. The MIP assay was able to detect the presence of the pathogen in infected Arabidopsis thaliana plants as soon as the tissues contained minimal amounts of pathogen. MIP methods are intrinsically highly multiplexable and future development of specific MIPs could lead to the establishment of a diagnostic method that could potentially screen infected plants for hundreds of pathogens in a single assay.

  18. Two novel transcriptional regulators are essential for infection-related morphogenesis and pathogenicity of the rice blast fungus Magnaporthe oryzae.

    Directory of Open Access Journals (Sweden)

    Xia Yan

    2011-12-01

    Full Text Available The cyclic AMP-dependent protein kinase A signaling pathway plays a major role in regulating plant infection by the rice blast fungus Magnaporthe oryzae. Here, we report the identification of two novel genes, MoSOM1 and MoCDTF1, which were discovered in an insertional mutagenesis screen for non-pathogenic mutants of M. oryzae. MoSOM1 or MoCDTF1 are both necessary for development of spores and appressoria by M. oryzae and play roles in cell wall differentiation, regulating melanin pigmentation and cell surface hydrophobicity during spore formation. MoSom1 strongly interacts with MoStu1 (Mstu1, an APSES transcription factor protein, and with MoCdtf1, while also interacting more weakly with the catalytic subunit of protein kinase A (CpkA in yeast two hybrid assays. Furthermore, the expression levels of MoSOM1 and MoCDTF1 were significantly reduced in both Δmac1 and ΔcpkA mutants, consistent with regulation by the cAMP/PKA signaling pathway. MoSom1-GFP and MoCdtf1-GFP fusion proteins localized to the nucleus of fungal cells. Site-directed mutagenesis confirmed that nuclear localization signal sequences in MoSom1 and MoCdtf1 are essential for their sub-cellular localization and biological functions. Transcriptional profiling revealed major changes in gene expression associated with loss of MoSOM1 during infection-related development. We conclude that MoSom1 and MoCdtf1 functions downstream of the cAMP/PKA signaling pathway and are novel transcriptional regulators associated with cellular differentiation during plant infection by the rice blast fungus.

  19. Novel Micro-organisms controlling plant pathogens

    OpenAIRE

    Köhl, J

    2009-01-01

    The invention relates to control of pathogen caused diseases on leaves, fruits and ears in plants, such as apple scab (Venturia inaequalis by treatment of plant with an isolate of Cladosporium cladosporioides. The treatment is effective in both prevention and treatment of the fungal infection

  20. EPCOT, NASA and plant pathogens in space.

    Science.gov (United States)

    White, R

    1996-01-01

    Cooperative work between NASA and Walt Disney World's EPCOT Land Pavilion is described. Joint efforts include research about allelopathy in multi-species plant cropping in CELSS, LEDs as light sources in hydroponic systems, and the growth of plant pathogens in space.

  1. The Trichoderma-plant interaction is mediated by avirulence proteins produced by this fungus

    Institute of Scientific and Technical Information of China (English)

    Ruocco M; Kip N; P J G M de Wit; Lorito M; Lanzuise S; Woo S L; Ambrosino P; Marra R; Turrà D; Gigante S; Formisno E; Scala F

    2004-01-01

    @@ The molecular basis of Trichoderma -plant interaction is very complex and still not completely understood. The colonization of the root system by rhizosphere competent strains of Trichoderma results in increased development of root/aerial systems, in improved yields and in plant disease control.Other beneficial effects, such as the induction of plant systemic resistance, have also been described.To understand the mechanisms involved we are using different approaches, including the making of transformants expressing genes that encode for compounds able to affect plant response to pathogens.Trichoderma transformants carrying the avirulence gene Avr4 from Cladosporium fulvum under the control of constitutive and inducible promoters were obtained and tested on tomato plants having the Cf4 resistance gene. Necrosis and suberification zones, similar to the symptoms appearing during Cladosporium-tomato interaction, were found when the roots of the Cf4 plants were treated with Avr4-Trichoderma. This demonstrates that selected Trichoderma strains are able to transfer to the plant molecules that may deeply affect metabolism, disease resistance etc. Therefore, these beneficial fungi can be regarded as biotechnological tools to provide a variety of crops with useful compounds.Moreover, in in vitro competition assays the transformants were found to be more effective as antagonists against Alternaria alternata than the wild type. Trichoderma sends a variety of biochemical signals to the plants including avirulence molecules; therefore the presence of avr-like proteins in the fungus proteome was investigated. Proteome analysis has permitted us to isolate and sequence many proteins potentially having this function. From the extraeellular protein extracts, we have purified and sequenced a protein with structural characteristics similar to Avr4 of C. fulvum.The protein, Hytra1, was found to be a hydrophobin with chitin binding activity, the typical 8cysteine residues, and 4

  2. Perturbations in the Primary Metabolism of Tomato and Arabidopsis thaliana Plants Infected with the Soil-Borne Fungus Verticillium dahliae.

    Directory of Open Access Journals (Sweden)

    Anja Buhtz

    Full Text Available The hemibiotrophic soil-borne fungus Verticillium dahliae is a major pathogen of a number of economically important crop species. Here, the metabolic response of both tomato and Arabidopsis thaliana to V. dahliae infection was analysed by first using non-targeted GC-MS profiling. The leaf content of both major cell wall components glucuronic acid and xylose was reduced in the presence of the pathogen in tomato but enhanced in A. thaliana. The leaf content of the two tricarboxylic acid cycle intermediates fumaric acid and succinic acid was increased in the leaf of both species, reflecting a likely higher demand for reducing equivalents required for defence responses. A prominent group of affected compounds was amino acids and based on the targeted analysis in the root, it was shown that the level of 12 and four free amino acids was enhanced by the infection in, respectively, tomato and A. thaliana, with leucine and histidine being represented in both host species. The leaf content of six free amino acids was reduced in the leaf tissue of diseased A. thaliana plants, while that of two free amino acids was raised in the tomato plants. This study emphasizes the role of primary plant metabolites in adaptive responses when the fungus has colonized the plant.

  3. Histone Acetylation in Fungal Pathogens of Plants

    Directory of Open Access Journals (Sweden)

    Junhyun Jeon

    2014-03-01

    Full Text Available Acetylation of histone lysine residues occurs in different organisms ranging from yeast to plants and mammals for the regulation of diverse cellular processes. With the identification of enzymes that create or reverse this modification, our understanding on histone acetylation has expanded at an amazing pace during the last two decades. In fungal pathogens of plants, however, the importance of such modification has only just begun to be appreciated in the recent years and there is a dearth of information on how histone acetylation is implicated in fungal pathogenesis. This review covers the current status of research related to histone acetylation in plant pathogenic fungi and considers relevant findings in the interaction between fungal pathogens and host plants. We first describe the families of histone acetyltransferases and deacetylases. Then we provide the cases where histone acetylation was investigated in the context of fungal pathogenesis. Finally, future directions and perspectives in epigenetics of fungal pathogenesis are discussed.

  4. Threats and opportunities of plant pathogenic bacteria.

    Science.gov (United States)

    Tarkowski, Petr; Vereecke, Danny

    2014-01-01

    Plant pathogenic bacteria can have devastating effects on plant productivity and yield. Nevertheless, because these often soil-dwelling bacteria have evolved to interact with eukaryotes, they generally exhibit a strong adaptivity, a versatile metabolism, and ingenious mechanisms tailored to modify the development of their hosts. Consequently, besides being a threat for agricultural practices, phytopathogens may also represent opportunities for plant production or be useful for specific biotechnological applications. Here, we illustrate this idea by reviewing the pathogenic strategies and the (potential) uses of five very different (hemi)biotrophic plant pathogenic bacteria: Agrobacterium tumefaciens, A. rhizogenes, Rhodococcus fascians, scab-inducing Streptomyces spp., and Pseudomonas syringae. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Light converts endosymbiotic fungus to pathogen, influencing seedling survival and niche-space filling of a common tropical tree, Iriartea deltoidea.

    Directory of Open Access Journals (Sweden)

    Patricia Álvarez-Loayza

    Full Text Available Pathogens are hypothesized to play an important role in the maintenance of tropical forest plant species richness. Notably, species richness may be promoted by incomplete filling of niche space due interactions of host populations with their pathogens. A potentially important group of pathogens are endophytic fungi, which asymptomatically colonize plants and are diverse and abundant in tropical ecosystems. Endophytes may alter competitive abilities of host individuals and improve host fitness under stress, but may also become pathogenic. Little is known of the impacts of endophytes on niche-space filling of their hosts.Here we evaluate how a widespread fungal endophyte infecting a common tropical palm influences its recruitment and survival in natural ecosystems, and whether this impact is modulated by the abiotic environment, potentially constraining host niche-space filling. Iriartea deltoidea dominates many wet lowland Neotropical forests. Diplodia mutila is a common asymptomatic endophyte in mature plants; however, it causes disease in some seedlings. We investigated the effects of light availability on D. mutila disease expression.We found I. deltoidea seedlings to preferentially occur under shady conditions. Correspondingly, we also found that high light triggers endophyte pathogenicity, while low light favors endosymbiotic development, constraining recruitment of endophyte-infested seedlings to shaded understory by reducing seedling survival in direct light. Pathogenicity of D. mutila under high light is proposed to result from light-induced production of H(2O(2 by the fungus, triggering hypersensitivity, cell death, and tissue necrosis in the palm. This is the first study to demonstrate that endophytes respond to abiotic factors to influence plant distributions in natural ecosystems; and the first to identify light as a factor influencing where an endophyte is placed on the endosymbiont-pathogen continuum. Our findings show that

  6. Effects of rainfall acidification on plant pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Shriner, D. S.; Cowling, E. B.

    1978-01-01

    Wind-blown rain, rain splash, and films of free moisture play important roles in the epidemiology of many plant diseases. The chemical nature of the aqueous microenvironment at the infection court is a potentially significant factor in the successful dissemination, establishment, and survival of plant pathogenic microorganisms. Acidic rainfall has a potential for influencing not only the pathogen, but also the host organism, and the host-pathogen complex. Although host-pathogen interactions add a degree of complexity to the study of abiotic environmental stress of plants, it is our hope, through the use of a combination of general concepts, theoretical postulations, and experimental data, to describe the potential role that rainfall acidity may play in the often subtle balance between populations of plants and populations of plant pathogens. The direct effects of acidic precipitation on vegetation are becoming increasingly better understood. The indirect consequences of both acute and chronic exposure of vegetation to acidic precipitation are very complex, however. Their effect is variable in time, and involves a variety of potential interactions which are only partially understood.

  7. Characterization of sakA gene from pathogenic dimorphic fungus Penicillium marneffei.

    Science.gov (United States)

    Nimmanee, Panjaphorn; Woo, Patrick C Y; Kummasook, Aksarakorn; Vanittanakom, Nongnuch

    2015-01-01

    Eukaryotes utilize stress activated protein kinase (SAPK) pathways to adapt to environmental stress, including heat, osmotic, oxidative or nutrient stresses. Penicillium marneffei (Talaromyces marneffei), the dimorphic pathogenic fungus that can cause disseminated mycosis in HIV-infected patients, has to encounter various types of stresses both outside and inside host cells. However, the strategies used by this fungus in response to these stresses are still unclear. In this report, the stress-activated kinase (sakA) gene of P. marneffei was characterized and the roles of this gene on various stress conditions were studied. The sakA gene deletion mutant was constructed using the split marker method. The phenotypes and sensitivities to varieties of stresses, including osmotic, oxidative, heat and cell wall stresses of the deletion mutant were compared with the wild type and the sakA complemented strains. Results demonstrated that the P. marneffei sakA gene encoded a putative protein containing TXY phosphorylation lip found in the stress high osmolarity glycerol 1 (Hog1)/Spc1/p38 MAPK family, and that this gene was involved not only in tolerance against oxidative and heat stresses, but also played a role in asexual development, chitin deposition, yeast cell generation in vitro and survival inside mouse and human macrophages.

  8. The rhizosphere microbial community in a multiple parallel mineralization system suppresses the pathogenic fungus Fusarium oxysporum.

    Science.gov (United States)

    Fujiwara, Kazuki; Iida, Yuichiro; Iwai, Takashi; Aoyama, Chihiro; Inukai, Ryuya; Ando, Akinori; Ogawa, Jun; Ohnishi, Jun; Terami, Fumihiro; Takano, Masao; Shinohara, Makoto

    2013-12-01

    The rhizosphere microbial community in a hydroponics system with multiple parallel mineralization (MPM) can potentially suppress root-borne diseases. This study focused on revealing the biological nature of the suppression against Fusarium wilt disease, which is caused by the fungus Fusarium oxysporum, and describing the factors that may influence the fungal pathogen in the MPM system. We demonstrated that the rhizosphere microbiota that developed in the MPM system could suppress Fusarium wilt disease under in vitro and greenhouse conditions. The microbiological characteristics of the MPM system were able to control the population dynamics of F. oxysporum, but did not eradicate the fungal pathogen. The roles of the microbiological agents underlying the disease suppression and the magnitude of the disease suppression in the MPM system appear to depend on the microbial density. F. oxysporum that survived in the MPM system formed chlamydospores when exposed to the rhizosphere microbiota. These results suggest that the microbiota suppresses proliferation of F. oxysporum by controlling the pathogen's morphogenesis and by developing an ecosystem that permits coexistence with F. oxysporum. © 2013 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

  9. Biochemical basis of synergism between pathogenic fungus Metarhizium anisopliae and insecticide chlorantraniliprole in Locusta migratoria (Meyen)

    Science.gov (United States)

    Jia, Miao; Cao, Guangchun; Li, Yibo; Tu, Xiongbing; Wang, Guangjun; Nong, Xiangqun; Whitman, Douglas W.; Zhang, Zehua

    2016-01-01

    We challenged Locusta migratoria (Meyen) grasshoppers with simultaneous doses of both the insecticide chlorantraniliprole and the fungal pathogen, Metarhizium anisopliae. Our results showed synergistic and antagonistic effects on host mortality and enzyme activities. To elucidate the biochemical mechanisms that underlie detoxification and pathogen-immune responses in insects, we monitored the activities of 10 enzymes. After administration of insecticide and fungus, activities of glutathione-S-transferase (GST), general esterases (ESTs) and phenol oxidase (PO) decreased in the insect during the initial time period, whereas those of aryl acylamidase (AA) and chitinase (CHI) increased during the initial period and that of acetylcholinesterase (AChE) increased during a later time period. Activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) decreased at a later time period post treatment. Interestingly, treatment with chlorantraniliprole and M. anisopliae relieved the convulsions that normally accompany M. anisopliae infection. We speculate that locust mortality increased as a result of synergism via a mechanism related to Ca2+ disruption in the host. Our study illuminates the biochemical mechanisms involved in insect immunity to xenobiotics and pathogens as well as the mechanisms by which these factors disrupt host homeostasis and induce death. We expect this knowledge to lead to more effective pest control. PMID:27328936

  10. Biochemical basis of synergism between pathogenic fungus Metarhizium anisopliae and insecticide chlorantraniliprole in Locusta migratoria (Meyen).

    Science.gov (United States)

    Jia, Miao; Cao, Guangchun; Li, Yibo; Tu, Xiongbing; Wang, Guangjun; Nong, Xiangqun; Whitman, Douglas W; Zhang, Zehua

    2016-06-22

    We challenged Locusta migratoria (Meyen) grasshoppers with simultaneous doses of both the insecticide chlorantraniliprole and the fungal pathogen, Metarhizium anisopliae. Our results showed synergistic and antagonistic effects on host mortality and enzyme activities. To elucidate the biochemical mechanisms that underlie detoxification and pathogen-immune responses in insects, we monitored the activities of 10 enzymes. After administration of insecticide and fungus, activities of glutathione-S-transferase (GST), general esterases (ESTs) and phenol oxidase (PO) decreased in the insect during the initial time period, whereas those of aryl acylamidase (AA) and chitinase (CHI) increased during the initial period and that of acetylcholinesterase (AChE) increased during a later time period. Activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) decreased at a later time period post treatment. Interestingly, treatment with chlorantraniliprole and M. anisopliae relieved the convulsions that normally accompany M. anisopliae infection. We speculate that locust mortality increased as a result of synergism via a mechanism related to Ca(2+) disruption in the host. Our study illuminates the biochemical mechanisms involved in insect immunity to xenobiotics and pathogens as well as the mechanisms by which these factors disrupt host homeostasis and induce death. We expect this knowledge to lead to more effective pest control.

  11. Biosynthesis of silver nanoparticles by the endophytic fungus Epicoccum nigrum and their activity against pathogenic fungi.

    Science.gov (United States)

    Qian, Yongqing; Yu, Huimei; He, Dan; Yang, Hui; Wang, Wanting; Wan, Xue; Wang, Li

    2013-11-01

    There is an enormous interest in developing safe, cost-effective and environmentally friendly technologies for nano-materials synthesis. In the present study, extracellular biosynthesis of silver nanoparticles was achieved by Epicoccum nigrum, an endophytic fungus isolated from the cambium of Phellodendron amurense. The reduction of the silver ions was monitored by UV-visible spectrophotometry, and the characterization of the Ag NPs was carried out by X-ray diffraction and transmission electron microscopy. The synthesized Ag NPs were exceptionally stable. It was found that an alkaline pH favored the formation of Ag NPs and elevated temperature accelerated the reduction process. Furthermore, the antifungal activity of the Ag NPs was assessed using a microdilution method. The biosynthesized Ag NPs showed considerable activity against the pathogenic fungi. The current research opens a new path for the green synthesis of Ag NPs and the process is easy to scale up for biomedical applications.

  12. The cell end marker Tea4 regulates morphogenesis and pathogenicity in the basidiomycete fungus Ustilago maydis.

    Science.gov (United States)

    Valinluck, Michael; Woraratanadharm, Tad; Lu, Ching-yu; Quintanilla, Rene H; Banuett, Flora

    2014-05-01

    Positional cues localized to distinct cell domains are critical for the generation of cell polarity and cell morphogenesis. These cues lead to assembly of protein complexes that organize the cytoskeleton resulting in delivery of vesicles to sites of polarized growth. Tea4, an SH3 domain protein, was first identified in fission yeast, and is a critical determinant of the axis of polarized growth, a role conserved among ascomycete fungi. Ustilago maydis is a badiomycete fungus that exhibits a yeast-like form that is nonpathogenic and a filamentous form that is pathogenic on maize and teozintle. We are interested in understanding how positional cues contribute to generation and maintenance of these two forms, and their role in pathogenicity. We identified a homologue of fission yeast tea4 in a genetic screen for mutants with altered colony and cell morphology and present here analysis of Tea4 for the first time in a basidiomycete fungus. We demonstrate that Tea4 is an important positional marker for polarized growth and septum location in both forms. We uncover roles for Tea4 in maintenance of cell and neck width, cell separation, and cell wall deposition in the yeast-like form, and in growth rate, formation of retraction septa, growth reversal, and inhibition of budding in the filamentous form. We show that Tea4::GFP localizes to sites of polarized or potential polarized growth in both forms, as observed in ascomycete fungi. We demonstrate an essential role of Tea4 in pathogencity in the absence of cell fusion. Basidiomycete and ascomycete Tea4 homologues share SH3 and Glc7 domains. Tea4 in basidiomycetes has additional domains, which has led us to hypothesize that Tea4 has novel functions in this group of fungi.

  13. Fungicide resistance assays for fungal plant pathogens.

    Science.gov (United States)

    Secor, Gary A; Rivera, Viviana V

    2012-01-01

    Fungicide resistance assays are useful to determine if a fungal pathogen has developed resistance to a fungicide used to manage the disease it causes. Laboratory assays are used to determine loss of sensitivity, or resistance, to a fungicide and can explain fungicide failures and for developing successful fungicide recommendations in the field. Laboratory assays for fungicide resistance are conducted by measuring reductions in growth or spore germination of fungi in the presence of fungicide, or by molecular procedures. This chapter describes two techniques for measuring fungicide resistance, using the sugarbeet leaf spot fungus Cercospora beticola as a model for the protocol. Two procedures are described for fungicides from two different classes; growth reduction for triazole (sterol demethylation inhibitor; DMI) fungicides, and inhibition of spore germination for quinone outside inhibitor (QoI) fungicides.

  14. THE INSECT PATHOGENIC FUNGUS Verticillium lecanii (Zimm. Viegas AND ITS USE FOR PESTS CONTROL: A REVIEW

    Directory of Open Access Journals (Sweden)

    Thiery B C ALAVO

    2015-08-01

    Full Text Available Chemical insecticides play an important role in the control of plant damage and plant diseases. However, extensive use of these products has led to the disruption of ecosystems because of several reasons such as death of non-target species, accumulation of pesticide residues in the environment and food, and buildup of pesticide resistance in the target species. Biological control is one of the alternatives to chemical pesticides and it can be described as the limitation of the abundance of living organisms and their products by other living organisms. Predators, parasitoids, fungi and other beneficial organisms can be used for the biocontrol of insect pests. The fungus Verticillium lecanii is one of the members of Deuteromycetes and it can be used for crop protection. This paper is a review of the international literature related to V. lecanii for the bio-control of insects of agricultural importance.

  15. Genome Analysis of a Zygomycete Fungus Choanephora cucurbitarum Elucidates Necrotrophic Features Including Bacterial Genes Related to Plant Colonization

    Science.gov (United States)

    Min, Byoungnam; Park, Ji-Hyun; Park, Hongjae; Shin, Hyeon-Dong; Choi, In-Geol

    2017-01-01

    A zygomycete fungus, Choanephora cucurbitarum is a plant pathogen that causes blossom rot in cucurbits and other plants. Here we report the genome sequence of Choanephora cucurbitarum KUS-F28377 isolated from squash. The assembled genome has a size of 29.1 Mbp and 11,977 protein-coding genes. The genome analysis indicated that C. cucurbitarum may employ a plant pathogenic mechanism similar to that of bacterial plant pathogens. The genome contained 11 genes with a Streptomyces subtilisin inhibitor-like domain, which plays an important role in the defense against plant immunity. This domain has been found only in bacterial genomes. Carbohydrate active enzyme analysis detected 312 CAZymes in this genome where carbohydrate esterase family 6, rarely found in dikaryotic fungal genomes, was comparatively enriched. The comparative genome analysis showed that the genes related to sexual communication such as the biosynthesis of β-carotene and trisporic acid were conserved and diverged during the evolution of zygomycete genomes. Overall, these findings will help us to understand how zygomycetes are associated with plants. PMID:28091548

  16. Retromer Is Essential for Autophagy-Dependent Plant Infection by the Rice Blast Fungus

    Science.gov (United States)

    He, Yunlong; Xie, Qiurong; Chen, Ahai; Zheng, Huawei; Shi, Lei; Zhao, Xu; Zhang, Chengkang; Huang, Qingping; Fang, Kunhai; Lu, Guodong; Ebbole, Daniel J.; Li, Guangpu; Naqvi, Naweed I.; Wang, Zonghua

    2015-01-01

    The retromer mediates protein trafficking through recycling cargo from endosomes to the trans-Golgi network in eukaryotes. However, the role of such trafficking events during pathogen-host interaction remains unclear. Here, we report that the cargo-recognition complex (MoVps35, MoVps26 and MoVps29) of the retromer is essential for appressorium-mediated host penetration by Magnaporthe oryzae, the causal pathogen of the blast disease in rice. Loss of retromer function blocked glycogen distribution and turnover of lipid bodies, delayed nuclear degeneration and reduced turgor during appressorial development. Cytological observation revealed dynamic MoVps35-GFP foci co-localized with autophagy-related protein RFP-MoAtg8 at the periphery of autolysosomes. Furthermore, RFP-MoAtg8 interacted with MoVps35-GFP in vivo, RFP-MoAtg8 was mislocalized to the vacuole and failed to recycle from the autolysosome in the absence of the retromer function, leading to impaired biogenesis of autophagosomes. We therefore conclude that retromer is essential for autophagy-dependent plant infection by the rice blast fungus. PMID:26658729

  17. The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens

    DEFF Research Database (Denmark)

    Moller, Isabel Eva; de Fine Licht, Henrik Hjarvard; Harholt, Jesper;

    2011-01-01

    The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus......, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste...... material that the ants remove from their fungus garden. These results demonstrate that biomass entering leaf-cutting ant fungus gardens is only partially utilized and explain why disproportionally large amounts of plant material are needed to sustain colony growth. They also explain why substantial...

  18. RNA-seq Transcriptome Response of Flax (Linum usitatissimum L.) to the Pathogenic Fungus Fusarium oxysporum f. sp. lini

    Science.gov (United States)

    Galindo-González, Leonardo; Deyholos, Michael K.

    2016-01-01

    Fusarium oxysporum f. sp. lini is a hemibiotrophic fungus that causes wilt in flax. Along with rust, fusarium wilt has become an important factor in flax production worldwide. Resistant flax cultivars have been used to manage the disease, but the resistance varies, depending on the interactions between specific cultivars and isolates of the pathogen. This interaction has a strong molecular basis, but no genomic information is available on how the plant responds to attempted infection, to inform breeding programs on potential candidate genes to evaluate or improve resistance across cultivars. In the current study, disease progression in two flax cultivars [Crop Development Center (CDC) Bethune and Lutea], showed earlier disease symptoms and higher susceptibility in the later cultivar. Chitinase gene expression was also divergent and demonstrated and earlier molecular response in Lutea. The most resistant cultivar (CDC Bethune) was used for a full RNA-seq transcriptome study through a time course at 2, 4, 8, and 18 days post-inoculation (DPI). While over 100 genes were significantly differentially expressed at both 4 and 8 DPI, the broadest deployment of plant defense responses was evident at 18 DPI with transcripts of more than 1,000 genes responding to the treatment. These genes evidenced a reception and transduction of pathogen signals, a large transcriptional reprogramming, induction of hormone signaling, activation of pathogenesis-related genes, and changes in secondary metabolism. Among these, several key genes that consistently appear in studies of plant-pathogen interactions, had increased transcript abundance in our study, and constitute suitable candidates for resistance breeding programs. These included: an induced RPMI-induced protein kinase; transcription factors WRKY3, WRKY70, WRKY75, MYB113, and MYB108; the ethylene response factors ERF1 and ERF14; two genes involved in auxin/glucosinolate precursor synthesis (CYP79B2 and CYP79B3); the flavonoid

  19. Combining microtomy and confocal laser scanning microscopy for structural analyses of plant-fungus associations.

    Science.gov (United States)

    Rath, Magnus; Grolig, Franz; Haueisen, Janine; Imhof, Stephan

    2014-05-01

    The serious problem of extended tissue thickness in the analysis of plant-fungus associations was overcome using a new method that combines physical and optical sectioning of the resin-embedded sample by microtomy and confocal microscopy. Improved tissue infiltration of the fungal-specific, high molecular weight fluorescent probe wheat germ agglutinin conjugated to Alexa Fluor® 633 resulted in high fungus-specific fluorescence even in deeper tissue sections. If autofluorescence was insufficient, additional counterstaining with Calcofluor White M2R or propidium iodide was applied in order to visualise the host plant tissues. Alternatively, the non-specific fluorochrome acid fuchsine was used for rapid staining of both, the plant and the fungal cells. The intricate spatial arrangements of the plant and fungal cells were preserved by immobilization in the hydrophilic resin Unicryl™. Microtomy was used to section the resin-embedded roots or leaves until the desired plane was reached. The data sets generated by confocal laser scanning microscopy of the remaining resin stubs allowed the precise spatial reconstruction of complex structures in the plant-fungus associations of interest. This approach was successfully tested on tissues from ectomycorrhiza (Betula pendula), arbuscular mycorrhiza (Galium aparine; Polygala paniculata, Polygala rupestris), ericoid mycorrhiza (Calluna vulgaris), orchid mycorrhiza (Limodorum abortivum, Serapias parviflora) and on one leaf-fungus association (Zymoseptoria tritici on Triticum aestivum). The method provides an efficient visualisation protocol applicable with a wide range of plant-fungus symbioses.

  20. Comparative analysis of twelve Dothideomycete plant pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Ohm, Robin; Aerts, Andrea; Salamov, Asaf; Goodwin, Stephen B.; Grigoriev, Igor

    2011-03-11

    The Dothideomycetes are one of the largest and most diverse groups of fungi. Many are plant pathogens and pose a serious threat to agricultural crops grown for biofuel, food or feed. Most Dothideomycetes have only a single host and related Dothideomycete species can have very diverse host plants. Twelve Dothideomycete genomes have currently been sequenced by the Joint Genome Institute and other sequencing centers. They can be accessed via Mycocosm which has tools for comparative analysis

  1. Fungal Control of Pathogenic Fungi Isolated From Some Wild Plants in Taif Governorate, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Abou-Zeid, A. M.

    2008-01-01

    Full Text Available Twenty two plants were collected from Taif Governorate and identified as: Aerva lanata, Arnebia hispidissima, Artemisia judaica, Artemisia monosperma, Asphodelus aestives, Avena barbata, Capparis dcidua, Eucalyptus globulus, Euphorbia glomerifera, Foeniculum vulgare, Forsskaolea tenacissima, Juniperus procera, Launaea mucronata, Launaea sonchoides, Medicago sativa, Opuntia ficus, Phagnalon sinaicum, Prunus persica, Pulicaria crispa, Punica granatum, Rumex dentatus and Trichodesma calathiforme. Pathogenic fungi were isolated from some of these plants and identified as Alternaria alternata, Cephalosporium madurae, Cladosporium herbarum, Fusarium oxysporum, Humicola grisea, Penicillium chrysogenum and Ulocladium botrytis. Four antagonistic isolates were tested, 2 from Gliocladium fungus and 2 from Trichoderma fungus. We found that all the four antagonistic isolates (G. deliquescens, G. virens, T. viride and T. hamatum significantly inhibited the radial growth of the pathogenic fungi tested, with different ratios. The results indicated that the antibiotics produced by the antagonists were more effective than the fungus itself and differ with different fungi. Coating plant stems with antagonists or with antagonist extracts reduce the severity of the disease but not prevent it in all tested pathogens.

  2. White-nose syndrome fungus: a generalist pathogen of hibernating bats.

    Directory of Open Access Journals (Sweden)

    Jan Zukal

    Full Text Available Host traits and phylogeny can determine infection risk by driving pathogen transmission and its ability to infect new hosts. Predicting such risks is critical when designing disease mitigation strategies, and especially as regards wildlife, where intensive management is often advocated or prevented by economic and/or practical reasons. We investigated Pseudogymnoascus [Geomyces] destructans infection, the cause of white-nose syndrome (WNS, in relation to chiropteran ecology, behaviour and phylogenetics. While this fungus has caused devastating declines in North American bat populations, there have been no apparent population changes attributable to the disease in Europe. We screened 276 bats of 15 species from hibernacula in the Czech Republic over 2012 and 2013, and provided histopathological evidence for 11 European species positive for WNS. With the exception of Myotis myotis, the other ten species are all new reports for WNS in Europe. Of these, M. emarginatus, Eptesicus nilssonii, Rhinolophus hipposideros, Barbastella barbastellus and Plecotus auritus are new to the list of P. destructans-infected bat species. While the infected species are all statistically phylogenetically related, WNS affects bats from two suborders. These are ecologically diverse and adopt a wide range of hibernating strategies. Occurrence of WNS in distantly related bat species with diverse ecology suggests that the pathogen may be a generalist and that all bats hibernating within the distribution range of P. destructans may be at risk of infection.

  3. Genome sequence of the insect pathogenic fungus Cordyceps militaris, a valued traditional chinese medicine

    Science.gov (United States)

    2011-01-01

    Background Species in the ascomycete fungal genus Cordyceps have been proposed to be the teleomorphs of Metarhizium species. The latter have been widely used as insect biocontrol agents. Cordyceps species are highly prized for use in traditional Chinese medicines, but the genes responsible for biosynthesis of bioactive components, insect pathogenicity and the control of sexuality and fruiting have not been determined. Results Here, we report the genome sequence of the type species Cordyceps militaris. Phylogenomic analysis suggests that different species in the Cordyceps/Metarhizium genera have evolved into insect pathogens independently of each other, and that their similar large secretomes and gene family expansions are due to convergent evolution. However, relative to other fungi, including Metarhizium spp., many protein families are reduced in C. militaris, which suggests a more restricted ecology. Consistent with its long track record of safe usage as a medicine, the Cordyceps genome does not contain genes for known human mycotoxins. We establish that C. militaris is sexually heterothallic but, very unusually, fruiting can occur without an opposite mating-type partner. Transcriptional profiling indicates that fruiting involves induction of the Zn2Cys6-type transcription factors and MAPK pathway; unlike other fungi, however, the PKA pathway is not activated. Conclusions The data offer a better understanding of Cordyceps biology and will facilitate the exploitation of medicinal compounds produced by the fungus. PMID:22112802

  4. Suppression of soil-borne plant pathogens

    NARCIS (Netherlands)

    Agtmaal, van M.

    2015-01-01

    Soil borne plant pathogens considerably reduce crop yields worldwide and are difficult to control due to their ”masked” occurrence  in the heterogeneous soil environment. This hampers the efficacy of chemical - and microbiological control agents.   Outbreaks of crop diseas

  5. Plant Fungal Pathogens: Methods and Protocols

    NARCIS (Netherlands)

    Bolton, M.D.; Thomma, B.P.H.J.

    2012-01-01

    Over the course of evolution, fungi have adapted to occupy specific niches, from symbiotically inhabiting the flora of the intestinal tract of mammals to saprophytic growth on leaf litter resting on the forest floor. In Plant Fungal Pathogens: Methods and Protocols, expert researchers in the field d

  6. Extraction of DNA from plant and fungus tissues in situ

    Directory of Open Access Journals (Sweden)

    Abu Almakarem Amal S

    2012-06-01

    Full Text Available Abstract Background When samples are collected in the field and transported to the lab, degradation of the nucleic acids contained in the samples is frequently observed. Immediate extraction and precipitation of the nucleic acids reduces degradation to a minimum, thus preserving accurate sequence information. An extraction method to obtain high quality DNA in field studies is described. Findings DNA extracted immediately after sampling was compared to DNA extracted after allowing the sampled tissues to air dry at 21°C for 48 or 72 hours. While DNA extracted from fresh tissues exhibited little degradation, DNA extracted from all tissues exposed to 21°C air for 48 or 72 hours exhibited varying degrees of degradation. Yield was higher for extractions from fresh tissues in most cases. Four microcentrifuges were compared for DNA yield: one standard electric laboratory microcentrifuge (max rcf = 16,000×g, two battery-operated microcentrifuges (max rcf = 5,000 and 3,000 ×g, and one manually-operated microcentrifuge (max rcf = 120×g. Yields for all centrifuges were similar. DNA extracted under simulated field conditions was similar in yield and quality to DNA extracted in the laboratory using the same equipment. Conclusions This CTAB (cetyltrimethylammonium bromide DNA extraction method employs battery-operated and manually-operated equipment to isolate high quality DNA in the field. The method was tested on plant and fungus tissues, and may be adapted for other types of organisms. The method produced high quality DNA in laboratory tests and under simulated field conditions. The field extraction method should prove useful for working in remote sites, where ice, dry ice, and liquid nitrogen are unavailable; where degradation is likely to occur due to the long distances between the sample site and the laboratory; and in instances where other DNA preservation and transportation methods have been unsuccessful. It may be possible to adapt

  7. Speciation in fungal and oomycete plant pathogens.

    Science.gov (United States)

    Restrepo, Silvia; Tabima, Javier F; Mideros, Maria F; Grünwald, Niklaus J; Matute, Daniel R

    2014-01-01

    The process of speciation, by definition, involves evolution of one or more reproductive isolating mechanisms that split a single species into two that can no longer interbreed. Determination of which processes are responsible for speciation is important yet challenging. Several studies have proposed that speciation in pathogens is heavily influenced by host-pathogen dynamics and that traits that mediate such interactions (e.g., host mobility, reproductive mode of the pathogen, complexity of the life cycle, and host specificity) must lead to reproductive isolation and ultimately affect speciation rates. In this review, we summarize the main evolutionary processes that lead to speciation of fungal and oomycete plant pathogens and provide an outline of how speciation can be studied rigorously, including novel genetic/genomic developments.

  8. Targeted Disruption of Melanin Biosynthesis Genes in the Human Pathogenic Fungus Lomentospora prolificans and Its Consequences for Pathogen Survival

    Directory of Open Access Journals (Sweden)

    Ayat Al-Laaeiby

    2016-03-01

    Full Text Available The dematiaceous (melanised fungus Lomentospora (Scedosporium prolificans is a life-threatening opportunistic pathogen of immunocompromised humans, resistant to anti-fungal drugs. Melanin has been shown to protect human pathogenic fungi against antifungal drugs, oxidative killing and environmental stresses. To determine the protective role of melanin in L. prolificans to oxidative killing (H2O2, UV radiation and the polyene anti-fungal drug amphotericin B, targeted gene disruption was used to generate mutants of the pathogen lacking the dihydroxynaphthalene (DHN-melanin biosynthetic enzymes polyketide synthase (PKS1, tetrahydroxynapthalene reductase (4HNR and scytalone dehydratase (SCD1. Infectious propagules (spores of the wild-type strain 3.1 were black/brown, whereas spores of the PKS-deficient mutant ΔLppks1::hph were white. Complementation of the albino mutant ΔLppks1::hph restored the black-brown spore pigmentation, while the 4HNR-deficient mutant ΔLp4hnr::hph and SCD-deficient mutant ΔLpscd1::hph both produced orange-yellow spores. The mutants ΔLppks1::hph and ΔLp4hnr::hph showed significant reductions in spore survival following H2O2 treatment, while spores of ΔLpscd1::hph and the ΔLppks1::hph complemented strain ΔLppks1::hph:PKS showed spore survivals similar to strain 3.1. Spores of the mutants ΔLp4hnr::hph and ΔLpscd1::hph and complemented strain ΔLppks1::hph:PKS showed spore survivals similar to 3.1 following exposure to UV radiation, but survival of ΔLppks1::hph spores was significantly reduced compared to the wild-type strain. Strain 3.1 and mutants ΔLp4hnr::hph and ΔLppks1::hph:PKS were resistant to amphotericin B while, paradoxically, the PKS1- and SCD1-deficient mutants showed significant increases in growth in the presence of the antifungal drug. Taken together, these results show that while melanin plays a protective role in the survival of the pathogen to oxidative killing and UV radiation, melanin does not

  9. Targeted Disruption of Melanin Biosynthesis Genes in the Human Pathogenic Fungus Lomentospora prolificans and Its Consequences for Pathogen Survival.

    Science.gov (United States)

    Al-Laaeiby, Ayat; Kershaw, Michael J; Penn, Tina J; Thornton, Christopher R

    2016-03-24

    The dematiaceous (melanised) fungus Lomentospora (Scedosporium) prolificans is a life-threatening opportunistic pathogen of immunocompromised humans, resistant to anti-fungal drugs. Melanin has been shown to protect human pathogenic fungi against antifungal drugs, oxidative killing and environmental stresses. To determine the protective role of melanin in L. prolificans to oxidative killing (H₂O₂), UV radiation and the polyene anti-fungal drug amphotericin B, targeted gene disruption was used to generate mutants of the pathogen lacking the dihydroxynaphthalene (DHN)-melanin biosynthetic enzymes polyketide synthase (PKS1), tetrahydroxynapthalene reductase (4HNR) and scytalone dehydratase (SCD1). Infectious propagules (spores) of the wild-type strain 3.1 were black/brown, whereas spores of the PKS-deficient mutant ΔLppks1::hph were white. Complementation of the albino mutant ΔLppks1::hph restored the black-brown spore pigmentation, while the 4HNR-deficient mutant ΔLp4hnr::hph and SCD-deficient mutant ΔLpscd1::hph both produced orange-yellow spores. The mutants ΔLppks1::hph and ΔLp4hnr::hph showed significant reductions in spore survival following H₂O₂ treatment, while spores of ΔLpscd1::hph and the ΔLppks1::hph complemented strain ΔLppks1::hph:PKS showed spore survivals similar to strain 3.1. Spores of the mutants ΔLp4hnr::hph and ΔLpscd1::hph and complemented strain ΔLppks1::hph:PKS showed spore survivals similar to 3.1 following exposure to UV radiation, but survival of ΔLppks1::hph spores was significantly reduced compared to the wild-type strain. Strain 3.1 and mutants ΔLp4hnr::hph and ΔLppks1::hph:PKS were resistant to amphotericin B while, paradoxically, the PKS1- and SCD1-deficient mutants showed significant increases in growth in the presence of the antifungal drug. Taken together, these results show that while melanin plays a protective role in the survival of the pathogen to oxidative killing and UV radiation, melanin does not

  10. The rhizosphere microbiome: significance of plant beneficial, plant pathogenic and human pathogenic microorganisms

    NARCIS (Netherlands)

    Mendes, R.; Garbeva, P.; Raaijmakers, J.M.

    2013-01-01

    Microbial communities play a pivotal role in the functioning of plants by influencing their physiology and development. While many members of the rhizosphere microbiome are beneficial to plant growth, also plant pathogenic microorganisms colonize the rhizosphere striving to break through the protect

  11. The rhizosphere microbiome: significance of plant beneficial, plant pathogenic and human pathogenic microorganisms

    NARCIS (Netherlands)

    Mendes, R.; Garbeva, P.; Raaijmakers, J.M.

    2013-01-01

    Microbial communities play a pivotal role in the functioning of plants by influencing their physiology and development. While many members of the rhizosphere microbiome are beneficial to plant growth, also plant pathogenic microorganisms colonize the rhizosphere striving to break through the protect

  12. The rhizosphere microbiome: significance of plant beneficial, plant pathogenic, and human pathogenic microorganisms

    NARCIS (Netherlands)

    Mendes, R.; Garbeva, P.V.; Raaijmakers, J.M.

    2013-01-01

    Microbial communities play a pivotal role in the functioning of plants by influencing their physiology and development. While many members of the rhizosphere microbiome are beneficial to plant growth, also plant pathogenic microorganisms colonize the rhizosphere striving to break through the protect

  13. Interactions between co-habitating fungi elicit synthesis of Taxol from an endophytic fungus in host Taxus plants

    Directory of Open Access Journals (Sweden)

    Sameh S.M. Soliman

    2013-01-01

    Full Text Available Within a plant, there can exist an ecosystem of pathogens and endophytes, the latter described as bacteria and fungal inhabitants that thrive without causing disease to the host. Interactions between microbial inhabitants represent a novel area of study for natural products research. Here we analyzed the interactions between the fungal endophytes of Taxus (yew trees. Fungal endophytes of Taxus have been proposed to produce the terpenoid secondary metabolite, Taxol, an anti-cancer drug. It is widely reported that plant extracts stimulate endophytic fungal Taxol production, but the underlying mechanism is not understood. Here, Taxus bark extracts stimulated fungal Taxol production 30-fold compared to a 10-fold induction with wood extracts. However, candidate plant-derived defence compounds (i.e. salicylic acid, benzoic acid were found to act only as modest elicitors of fungal Taxol production from the endophytic fungus Paraconiothyrium SSM001, consistent with previous studies. We hypothesized the Taxus plant extracts may contain elicitors derived from other microbes inhabiting these tissues. We investigated the effects of co-culturing SSM001 with other fungi observed to inhabit Taxus bark, but not wood. Surprisingly, co-culture of SSM001 with a bark fungus (Alternaria caused a ~3-fold increase in Taxol production. When SSM001 was pyramided with both the Alternaria endophyte along with another fungus (Phomopsis observed to inhabit Taxus, there was an ~eight-fold increase in fungal Taxol production from SSM001. These results suggest that resident fungi within a host plant interact with one another to stimulate Taxol biosynthesis, either directly or through their metabolites. More generally, our results suggest that endophyte secondary metabolism should be studied in the context of its native ecosystem.

  14. Interactions between Co-Habitating fungi Elicit Synthesis of Taxol from an Endophytic Fungus in Host Taxus Plants.

    Science.gov (United States)

    Soliman, Sameh S M; Raizada, Manish N

    2013-01-01

    Within a plant, there can exist an ecosystem of pathogens and endophytes, the latter described as bacterial and fungal inhabitants that thrive without causing disease to the host. Interactions between microbial inhabitants represent a novel area of study for natural products research. Here we analyzed the interactions between the fungal endophytes of Taxus (yew) trees. Fungal endophytes of Taxus have been proposed to produce the terpenoid secondary metabolite, Taxol, an anti-cancer drug. It is widely reported that plant extracts stimulate endophytic fungal Taxol production, but the underlying mechanism is not understood. Here, Taxus bark extracts stimulated fungal Taxol production 30-fold compared to a 10-fold induction with wood extracts. However, candidate plant-derived defense compounds (i.e., salicylic acid, benzoic acid) were found to act only as modest elicitors of fungal Taxol production from the endophytic fungus Paraconiothyrium SSM001, consistent with previous studies. We hypothesized the Taxus plant extracts may contain elicitors derived from other microbes inhabiting these tissues. We investigated the effects of co-culturing SSM001 with other fungi observed to inhabit Taxus bark, but not wood. Surprisingly, co-culture of SSM001 with a bark fungus (Alternaria) caused a ∼threefold increase in Taxol production. When SSM001 was pyramided with both the Alternaria endophyte along with another fungus (Phomopsis) observed to inhabit Taxus, there was an ∼eightfold increase in fungal Taxol production from SSM001. These results suggest that resident fungi within a host plant interact with one another to stimulate Taxol biosynthesis, either directly or through their metabolites. More generally, our results suggest that endophyte secondary metabolism should be studied in the context of its native ecosystem.

  15. Transcriptome characterization of the dimorphic and pathogenic fungus Paracoccidioides brasiliensis by EST analysis.

    Science.gov (United States)

    Felipe, M S S; Andrade, R V; Petrofeza, S S; Maranhão, A Q; Torres, F A G; Albuquerque, P; Arraes, F B M; Arruda, M; Azevedo, M O; Baptista, A J; Bataus, L A M; Borges, C L; Campos, E G; Cruz, M R; Daher, B S; Dantas, A; Ferreira, M A S V; Ghil, G V; Jesuino, R S A; Kyaw, C M; Leitão, L; Martins, C R; Moraes, L M P; Neves, E O; Nicola, A M; Alves, E S; Parente, J A; Pereira, M; Poças-Fonseca, M J; Resende, R; Ribeiro, B M; Saldanha, R R; Santos, S C; Silva-Pereira, I; Silva, M A S; Silveira, E; Simões, I C; Soares, R B A; Souza, D P; De-Souza, M T; Andrade, E V; Xavier, M A S; Veiga, H P; Venancio, E J; Carvalho, M J A; Oliveira, A G; Inoue, M K; Almeida, N F; Walter, M E M T; Soares, C M A; Brígido, M M

    2003-02-01

    Paracoccidioides brasiliensis is a pathogenic fungus that undergoes a temperature-dependent cell morphology change from mycelium (22 degrees C) to yeast (36 degrees C). It is assumed that this morphological transition correlates with the infection of the human host. Our goal was to identify genes expressed in the mycelium (M) and yeast (Y) forms by EST sequencing in order to generate a partial map of the fungus transcriptome. Individual EST sequences were clustered by the CAP3 program and annotated using Blastx similarity analysis and InterPro Scan. Three different databases, GenBank nr, COG (clusters of orthologous groups) and GO (gene ontology) were used for annotation. A total of 3,938 (Y = 1,654 and M = 2,274) ESTs were sequenced and clustered into 597 contigs and 1,563 singlets, making up a total of 2,160 genes, which possibly represent one-quarter of the complete gene repertoire in P. brasiliensis. From this total, 1,040 were successfully annotated and 894 could be classified in 18 functional COG categories as follows: cellular metabolism (44%); information storage and processing (25%); cellular processes-cell division, posttranslational modifications, among others (19%); and genes of unknown functions (12%). Computer analysis enabled us to identify some genes potentially involved in the dimorphic transition and drug resistance. Furthermore, computer subtraction analysis revealed several genes possibly expressed in stage-specific forms of P. brasiliensis. Further analysis of these genes may provide new insights into the pathology and differentiation of P. brasiliensis.

  16. [Mechanism of tomato plants enhanced disease resistance against early blight primed by arbuscular mycorrhizal fungus Glomus versiforme].

    Science.gov (United States)

    Song, Yuan-yuan; Wang, Rui-long; Wei, Xiao-chen; Lu, Yong-jian; Tang, Zhao-yang; Wu, Guo-zhao; Su, Yi-juan; Zeng, Ren-sen

    2011-09-01

    Arbuscular mycorrhiza (AM) can not only improve host plants nutrient absorption, but also enhance their disease resistance. Taking the tomato (Lycopersicon esculentum) seedlings preinoculated with axbuscular mycorrhizal fungus (AMF) Glomus versiforme as test materials, this paper studied their protective enzyme activities and defense-related genes expression, and their resistance against a fungal pathogen Alternaria solani Sorauer which causes early blight. The seedlings pre-inoculated with AMF and later inoculated with A. solani showed significantly higher activities of superoxide dismutase (SOD) and peroxidase (POD) in leaves. The leaf SOD activity of the dually inoculated plants reached the maximum 18 h after pathogen inoculation, being 28.6%, 79.2% and 82.8% higher than that of the plants with G. versiforme inoculation alone, pathogen inoculation alone, and non-inoculation, and the Leaf POD activity reached the maximum 65 h after pathogen inoculation, being 762%, 18.3%, and 1710% higher, respectively. Real time RT-PCR analysis showed that dual inoculation with C. versiforme and A. solani strongly induced the expression of three defense-related genes. The transcript levels of pathogen-related protein (PR1), basic type beta-1,3-glucanase (PR-2), and chitinase (PR-3) in leaves were 9.67-, 8.54-, and 13.4-fold higher, as compared with the non-inoculation control, respectively. Bioassay showed that the disease incidence and disease index of the seedlings pre-inoculated with C. versiforme were reduced by 36.3% and 61.4%, respectively, as compared with the non-mycorrhizal control plants. These findings indicated that mycorrhizal colonization could induce stronger and quicker defense responses of host tomato plants, and priming could be an important mechanism of the enhanced disease resistance of mycorrhizal tomato plants.

  17. Phytophagous arthropods and a pathogen sharing a host plant: evidence for indirect plant-mediated interactions.

    Directory of Open Access Journals (Sweden)

    Raphaëlle Mouttet

    Full Text Available In ecological systems, indirect interactions between plant pathogens and phytophagous arthropods can arise when infestation by a first attacker alters the common host plant so that although a second attacker could be spatially or temporally separated from the first one, the former could be affected. The induction of plant defense reactions leading to the production of secondary metabolites is thought to have an important role since it involves antagonistic and/or synergistic cross-talks that may determine the outcome of such interactions. We carried out experiments under controlled conditions on young rose plants in order to assess the impact of these indirect interactions on life history traits of three pests: the necrotrophic fungus Botrytis cinerea Pers.: Fr. (Helotiales: Sclerotiniaceae, the aphid Rhodobium porosum Sanderson (Hemiptera: Aphididae and the thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae. Our results indicated (i a bi-directional negative interaction between B. cinerea and R. porosum, which is conveyed by decreased aphid growth rate and reduced fungal lesion area, as well as (ii an indirect negative effect of B. cinerea on insect behavior. No indirect effect was observed between thrips and aphids. This research highlights several complex interactions that may be involved in structuring herbivore and plant pathogen communities within natural and managed ecosystems.

  18. Failure of the mite-pathogenic fungus Neozygites tanajoae and the predatory mite Neoseiulus idaeus to control a population of the cassava green mite, Mononychellus tanajoa.

    Science.gov (United States)

    Elliot, Simon L; de Moraes, Gilberto J; Mumford, John D

    2008-12-01

    Monitoring of a population of the phytophagous cassava green mite, Mononychellus tanajoa (Bondar), and its natural enemies was undertaken in central Bahia, Brazil, in mid-1996. In spite of the presence of extremely high densities of the predatory phytoseiid mite Neoseiulus idaeus Denmark & Muma, the phytophagous mite population reached such high densities itself that there was total overexploitation of the cassava plants, leading to total leaf loss. Meanwhile, the mite-pathogenic fungus Neozygites tanajoae Delalibera, Humber & Hajek did not affect the M. tanajoa population in its growth phase as there was no inoculum present, even though we predict from a simple regression model that there was the potential for epizootics at that time. Soon after the M. tanajoa population crashed due to defoliation, there could have been an epizootic but there were simply no mite hosts to infect. These data demonstrate the ineffectiveness of one natural enemy (the predator) in terms of prey population regulation and demonstrate the importance of timing in the possible effectiveness of the other (the pathogen). For the pathogen, this probably explains its sporadic effect on host populations as previously reported. We conclude that the fungus is likely to be most useful as an adjunct to biological control with predatory mites other than N. idaeus.

  19. Pathogenic chytrid fungus Batrachochytrium dendrobatidis, but not B. salamandrivorans, detected on eastern hellbenders.

    Directory of Open Access Journals (Sweden)

    Emma K Bales

    Full Text Available Recent worldwide declines and extinctions of amphibian populations have been attributed to chytridiomycosis, a disease caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd. Until recently, Bd was thought to be the only Batrachochytrium species that infects amphibians; however a newly described species, Batrachochytrium salamandrivorans (Bs, is linked to die-offs in European fire salamanders (Salamandra salamandra. Little is known about the distribution, host range, or origin of Bs. In this study, we surveyed populations of an aquatic salamander that is declining in the United States, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis, for the presence of Bs and Bd. Skin swabs were collected from a total of 91 individuals in New York, Pennsylvania, Ohio, and Virginia, and tested for both pathogens using duplex qPCR. Bs was not detected in any samples, suggesting it was not present in these hellbender populations (0% prevalence, 95% confidence intervals of 0.0-0.04. Bd was found on 22 hellbenders (24% prevalence, 95% confidence intervals of 0.16 ≤ 0.24 ≤ 0.34, representing all four states. All positive samples had low loads of Bd zoospores (12.7 ± 4.9 S.E.M. genome equivalents compared to other Bd susceptible species. More research is needed to determine the impact of Batrachochytrium infection on hellbender fitness and population viability. In particular, understanding how hellbenders limit Bd infection intensity in an aquatic environment may yield important insights for amphibian conservation. This study is among the first to evaluate the distribution of Bs in the United States, and is consistent with another, which failed to detect Bs in the U.S. Knowledge about the distribution, host-range, and origin of Bs may help control the spread of this pathogen, especially to regions of high salamander diversity, such as the eastern United States.

  20. Pathogenic chytrid fungus Batrachochytrium dendrobatidis, but not B. salamandrivorans, detected on eastern hellbenders.

    Science.gov (United States)

    Bales, Emma K; Hyman, Oliver J; Loudon, Andrew H; Harris, Reid N; Lipps, Gregory; Chapman, Eric; Roblee, Kenneth; Kleopfer, John D; Terrell, Kimberly A

    2015-01-01

    Recent worldwide declines and extinctions of amphibian populations have been attributed to chytridiomycosis, a disease caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). Until recently, Bd was thought to be the only Batrachochytrium species that infects amphibians; however a newly described species, Batrachochytrium salamandrivorans (Bs), is linked to die-offs in European fire salamanders (Salamandra salamandra). Little is known about the distribution, host range, or origin of Bs. In this study, we surveyed populations of an aquatic salamander that is declining in the United States, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis), for the presence of Bs and Bd. Skin swabs were collected from a total of 91 individuals in New York, Pennsylvania, Ohio, and Virginia, and tested for both pathogens using duplex qPCR. Bs was not detected in any samples, suggesting it was not present in these hellbender populations (0% prevalence, 95% confidence intervals of 0.0-0.04). Bd was found on 22 hellbenders (24% prevalence, 95% confidence intervals of 0.16 ≤ 0.24 ≤ 0.34), representing all four states. All positive samples had low loads of Bd zoospores (12.7 ± 4.9 S.E.M. genome equivalents) compared to other Bd susceptible species. More research is needed to determine the impact of Batrachochytrium infection on hellbender fitness and population viability. In particular, understanding how hellbenders limit Bd infection intensity in an aquatic environment may yield important insights for amphibian conservation. This study is among the first to evaluate the distribution of Bs in the United States, and is consistent with another, which failed to detect Bs in the U.S. Knowledge about the distribution, host-range, and origin of Bs may help control the spread of this pathogen, especially to regions of high salamander diversity, such as the eastern United States.

  1. The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens.

    Directory of Open Access Journals (Sweden)

    Isabel E Moller

    Full Text Available The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus degrades cellulose have hampered our understanding of the selection forces that induced large scale herbivory and of the ensuing ecological footprint of these ants. Here we use a recently established technique, based on polysaccharide microarrays probed with antibodies and carbohydrate binding modules, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste material that the ants remove from their fungus garden. These results demonstrate that biomass entering leaf-cutting ant fungus gardens is only partially utilized and explain why disproportionally large amounts of plant material are needed to sustain colony growth. They also explain why substantial communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated with fungus-farming in ants.

  2. Paleogene radiation of a plant pathogenic mushroom.

    Directory of Open Access Journals (Sweden)

    Martin P A Coetzee

    Full Text Available BACKGROUND: The global movement and speciation of fungal plant pathogens is important, especially because of the economic losses they cause and the ease with which they are able to spread across large areas. Understanding the biogeography and origin of these plant pathogens can provide insights regarding their dispersal and current day distribution. We tested the hypothesis of a Gondwanan origin of the plant pathogenic mushroom genus Armillaria and the currently accepted premise that vicariance accounts for the extant distribution of the species. METHODS: The phylogeny of a selection of Armillaria species was reconstructed based on Maximum Parsimony (MP, Maximum Likelihood (ML and Bayesian Inference (BI. A timeline was then placed on the divergence of lineages using a Bayesian relaxed molecular clock approach. RESULTS: Phylogenetic analyses of sequenced data for three combined nuclear regions provided strong support for three major geographically defined clades: Holarctic, South American-Australasian and African. Molecular dating placed the initial radiation of the genus at 54 million years ago within the Early Paleogene, postdating the tectonic break-up of Gondwana. CONCLUSIONS: The distribution of extant Armillaria species is the result of ancient long-distance dispersal rather than vicariance due to continental drift. As these finding are contrary to most prior vicariance hypotheses for fungi, our results highlight the important role of long-distance dispersal in the radiation of fungal pathogens from the Southern Hemisphere.

  3. A fungal symbiont of plant-roots modulates mycotoxin gene expression in the pathogen Fusarium sambucinum.

    Directory of Open Access Journals (Sweden)

    Youssef Ismail

    Full Text Available Fusarium trichothecenes are fungal toxins that cause disease on infected plants and, more importantly, health problems for humans and animals that consume infected fruits or vegetables. Unfortunately, there are few methods for controlling mycotoxin production by fungal pathogens. In this study, we isolated and characterized sixteen Fusarium strains from naturally infected potato plants in the field. Pathogenicity tests were carried out in the greenhouse to evaluate the virulence of the strains on potato plants as well as their trichothecene production capacity, and the most aggressive strain was selected for further studies. This strain, identified as F. sambucinum, was used to determine if trichothecene gene expression was affected by the symbiotic Arbuscular mycorrhizal fungus (AMF Glomus irregulare. AMF form symbioses with plant roots, in particular by improving their mineral nutrient uptake and protecting plants against soil-borne pathogens. We found that that G. irregulare significantly inhibits F. sambucinum growth. We also found, using RT-PCR assays to assess the relative expression of trichothecene genes, that in the presence of the AMF G. irregulare, F. sambucinum genes TRI5 and TRI6 were up-regulated, while TRI4, TRI13 and TRI101 were down-regulated. We conclude that AMF can modulate mycotoxin gene expression by a plant fungal pathogen. This previously undescribed effect may be an important mechanism for biological control and has fascinating implications for advancing our knowledge of plant-microbe interactions and controlling plant pathogens.

  4. A fungal symbiont of plant-roots modulates mycotoxin gene expression in the pathogen Fusarium sambucinum.

    Science.gov (United States)

    Ismail, Youssef; McCormick, Susan; Hijri, Mohamed

    2011-03-24

    Fusarium trichothecenes are fungal toxins that cause disease on infected plants and, more importantly, health problems for humans and animals that consume infected fruits or vegetables. Unfortunately, there are few methods for controlling mycotoxin production by fungal pathogens. In this study, we isolated and characterized sixteen Fusarium strains from naturally infected potato plants in the field. Pathogenicity tests were carried out in the greenhouse to evaluate the virulence of the strains on potato plants as well as their trichothecene production capacity, and the most aggressive strain was selected for further studies. This strain, identified as F. sambucinum, was used to determine if trichothecene gene expression was affected by the symbiotic Arbuscular mycorrhizal fungus (AMF) Glomus irregulare. AMF form symbioses with plant roots, in particular by improving their mineral nutrient uptake and protecting plants against soil-borne pathogens. We found that that G. irregulare significantly inhibits F. sambucinum growth. We also found, using RT-PCR assays to assess the relative expression of trichothecene genes, that in the presence of the AMF G. irregulare, F. sambucinum genes TRI5 and TRI6 were up-regulated, while TRI4, TRI13 and TRI101 were down-regulated. We conclude that AMF can modulate mycotoxin gene expression by a plant fungal pathogen. This previously undescribed effect may be an important mechanism for biological control and has fascinating implications for advancing our knowledge of plant-microbe interactions and controlling plant pathogens.

  5. Modulation of Plant RAB GTPase-Mediated Membrane Trafficking Pathway at the Interface Between Plants and Obligate Biotrophic Pathogens.

    Science.gov (United States)

    Inada, Noriko; Betsuyaku, Shigeyuki; Shimada, Takashi L; Ebine, Kazuo; Ito, Emi; Kutsuna, Natsumaro; Hasezawa, Seiichiro; Takano, Yoshitaka; Fukuda, Hiroo; Nakano, Akihiko; Ueda, Takashi

    2016-09-01

    RAB5 is a small GTPase that acts in endosomal trafficking. In addition to canonical RAB5 members that are homologous to animal RAB5, land plants harbor a plant-specific RAB5, the ARA6 group, which regulates trafficking events distinct from canonical RAB5 GTPases. Here, we report that plant RAB5, both canonical and plant-specific members, accumulate at the interface between host plants and biotrophic fungal and oomycete pathogens. Biotrophic fungi and oomycetes colonize living plant tissues by establishing specialized infection hyphae, the haustorium, within host plant cells. We found that Arabidopsis thaliana ARA6/RABF1, a plant-specific RAB5, is localized to the specialized membrane that surrounds the haustorium, the extrahaustorial membrane (EHM), formed by the A. thaliana-adapted powdery mildew fungus Golovinomyces orontii Whereas the conventional RAB5 ARA7/RABF2b was also localized to the EHM, endosomal SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) and RAB5-activating proteins were not, which suggests that the EHM has modified endosomal characteristic. The recruitment of host RAB5 to the EHM was a property shared by the barley-adapted powdery mildew fungus Blumeria graminis f.sp. hordei and the oomycete Hyaloperonospora arabidopsidis, but the extrahyphal membrane surrounding the hypha of the hemibiotrophic fungus Colletotrichum higginsianum at the biotrophic stage was devoid of RAB5. The localization of RAB5 to the EHM appears to correlate with the functionality of the haustorium. Our discovery sheds light on a novel relationship between plant RAB5 and obligate biotrophic pathogens.

  6. Arbuscular mycorrhiza detoxifying response against arsenic and pathogenic fungus in soybean.

    Science.gov (United States)

    Spagnoletti, Federico N; Balestrasse, Karina; Lavado, Raúl S; Giacometti, Romina

    2016-11-01

    Uptake of Arsenic (As) in plant tissues can affect metabolism, causing physiological disorders, even death. As toxicity, but also pathogen infections trigger a generalised stress response called oxidative stress; however knowledge on the response of soybean (Glycine max L.) under multiple stressors is limited so far. Arbuscular mycorrhizal fungi (AMF) enhance the tolerance of host plants to abiotic and biotic stress. Thus, we investigated the effects of the AMF Rhizophagus intraradices on soybean grown in As-contaminated soils as well as in the presence of the pathogen Macrophomina phaseolina (charcoal rot of the stem). Plant parameters and degree of mycorrhizal colonization under the different assessed treatments were analyzed. Content of As in roots and leaves was quantified. Increasing As level in the soil stopped plant growth, but promoted plant As uptake. Inoculation of soybean plants with M. phaseolina accentuated As effect at all physiological levels. In the presence of mycorrhizal symbiosis biomass dramatically increased, and significantly reduced the As concentration in plant tissues. Mycorrhization decreased oxidative damage in the presence of both As and the pathogen. Furthermore, transcription analysis revealed that the high-affinity phosphate transporter from R. intraradices RiPT and the gene encoding a putative arsenic efflux pump RiArsA were up-regulated under higher As doses. These results suggest that R. intraradices is most likely to get involved in the defense response against M. phaseolina, but also in the reduction of arsenate to arsenite as a possible detoxification mechanism in AMF associations in soybean. R. intraradices actively participates in the soybean antioxidant defense response against arsenic stress and M. phaseolina infection. Copyright © 2016. Published by Elsevier Inc.

  7. Transcriptomic analysis of Ustilago maydis infecting Arabidopsis reveals important aspects of the fungus pathogenic mechanisms.

    Science.gov (United States)

    Martínez-Soto, Domingo; Robledo-Briones, Angélica M; Estrada-Luna, Andrés A; Ruiz-Herrera, José

    2013-08-01

    Transcriptomic and biochemical analyses of the experimental pathosystem constituted by Ustilago maydis and Arabidopsis thaliana were performed. Haploid or diploid strains of U. maydis inoculated in A. thaliana plantlets grew on the surface and within the plant tissues in the form of mycelium, inducing chlorosis, anthocyanin formation, malformations, necrosis and adventitious roots development, but not teliospores. Symptoms were more severe in plants inoculated with the haploid strain which grew more vigorously than the diploid strain. RNA extracted at different times post-infection was used for hybridization of one-channel microarrays that were analyzed focusing on the fungal genes involved in the general pathogenic process, biogenesis of the fungal cell wall and the secretome. In total, 3,537 and 3,299 genes were differentially expressed in the haploid and diploid strains, respectively. Differentially expressed genes were related to different functional categories and many of them showed a similar regulation occurring in U. maydis infecting maize. Our data suggest that the haploid strain behaves as a necrotrophic pathogen, whereas the diploid behaves as a biotrophic pathogen. The results obtained are evidence of the usefulness of the U. maydis-A. thaliana pathosystem for the analysis of the pathogenic mechanisms of U. maydis.

  8. Methods of estimation of the pathogenicity of the fungus Phoma exigua var. exigua

    Directory of Open Access Journals (Sweden)

    Joanna Marcinkowska

    2013-12-01

    Full Text Available During the period 1977-1981 33 isolates of Phoma exigua were recovered from diseased leaves, stems, root crowns and seeds of soybean cultivated in different localities of Poland. None of the obtained isolates caused disease symptoms on soybean and other plant species when they were inoculated by spraying with conidial suspension. Infection developed only on wounded plants after inoculation. Phoma exigua occurring on soybean in Poland is not a specialized pathogen of this plant, but a plurivorous weak or waund parasite which attacks all kinds of plants and so is P. exigua var. exigua. Among seven of the applied inoculation methods the best one seems to be the laboratory one, in Petri plates, with culture discs exposed on the seedling hypocotyl. Other methods varied in precision and were more time-consuming.

  9. Virulence determinants of the human pathogenic fungus Aspergillus fumigatus protect against soil amoeba predation.

    Science.gov (United States)

    Hillmann, Falk; Novohradská, Silvia; Mattern, Derek J; Forberger, Tilmann; Heinekamp, Thorsten; Westermann, Martin; Winckler, Thomas; Brakhage, Axel A

    2015-08-01

    Filamentous fungi represent classical examples for environmentally acquired human pathogens whose major virulence mechanisms are likely to have emerged long before the appearance of innate immune systems. In natural habitats, amoeba predation could impose a major selection pressure towards the acquisition of virulence attributes. To test this hypothesis, we exploited the amoeba Dictyostelium discoideum to study its interaction with Aspergillus fumigatus, two abundant soil inhabitants for which we found co-occurrence in various sites. Fungal conidia were efficiently taken up by D. discoideum, but ingestion was higher when conidia were devoid of the green fungal spore pigment dihydroxynaphtalene melanin, in line with earlier results obtained for immune cells. Conidia were able to survive phagocytic processing, and intracellular germination was initiated only after several hours of co-incubation which eventually led to a lethal disruption of the host cell. Besides phagocytic interactions, both amoeba and fungus secreted cross inhibitory factors which suppressed fungal growth or induced amoeba aggregation with subsequent cell lysis, respectively. On the fungal side, we identified gliotoxin as the major fungal factor killing Dictyostelium, supporting the idea that major virulence attributes, such as escape from phagocytosis and the secretion of mycotoxins are beneficial to escape from environmental predators.

  10. Unlikely remedy: fungicide clears infection from pathogenic fungus in larval southern leopard frogs (Lithobates sphenocephalus.

    Directory of Open Access Journals (Sweden)

    Shane M Hanlon

    Full Text Available Amphibians are often exposed to a wide variety of perturbations. Two of these, pesticides and pathogens, are linked to declines in both amphibian health and population viability. Many studies have examined the separate effects of such perturbations; however, few have examined the effects of simultaneous exposure of both to amphibians. In this study, we exposed larval southern leopard frog tadpoles (Lithobates sphenocephalus to the chytrid fungus Batrachochytrium dendrobatidis and the fungicide thiophanate-methyl (TM at 0.6 mg/L under laboratory conditions. The experiment was continued until all larvae completed metamorphosis or died. Overall, TM facilitated increases in tadpole mass and length. Additionally, individuals exposed to both TM and Bd were heavier and larger, compared to all other treatments. TM also cleared Bd in infected larvae. We conclude that TM affects larval anurans to facilitate growth and development while clearing Bd infection. Our findings highlight the need for more research into multiple perturbations, specifically pesticides and disease, to further promote amphibian heath.

  11. Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America

    Science.gov (United States)

    Chestnut, Tara E.; Anderson, Chauncey; Popa, Radu; Blaustein, Andrew R.; Voytek, Mary; Olson, Deanna H.; Kirshtein, Julie

    2014-01-01

    Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L−1. The highest density observed was ∼3 million zoospores L−1. We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure to free-living Bd in aquatic

  12. Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America.

    Directory of Open Access Journals (Sweden)

    Tara Chestnut

    Full Text Available Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd, is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L(-1. The highest density observed was ∼3 million zoospores L(-1. We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure to free

  13. Specific, non-nutritional association between an ascomycete fungus and Allomerus plant-ants.

    Science.gov (United States)

    Ruiz-González, Mario X; Malé, Pierre-Jean G; Leroy, Céline; Dejean, Alain; Gryta, Hervé; Jargeat, Patricia; Quilichini, Angélique; Orivel, Jérôme

    2011-06-23

    Ant-fungus associations are well known from attine ants, whose nutrition is based on a symbiosis with basidiomycete fungi. Otherwise, only a few non-nutritional ant-fungus associations have been recorded to date. Here we focus on one of these associations involving Allomerus plant-ants that build galleried structures on their myrmecophytic hosts in order to ambush prey. We show that this association is not opportunistic because the ants select from a monophyletic group of closely related fungal haplotypes of an ascomycete species from the order Chaetothyriales that consistently grows on and has been isolated from the galleries. Both the ants' behaviour and an analysis of the genetic population structure of the ants and the fungus argue for host specificity in this interaction. The ants' behaviour reveals a major investment in manipulating, growing and cleaning the fungus. A molecular analysis of the fungus demonstrates the widespread occurrence of one haplotype and many other haplotypes with a lower occurrence, as well as significant variation in the presence of these fungal haplotypes between areas and ant species. Altogether, these results suggest that such an interaction might represent an as-yet undescribed type of specific association between ants and fungus in which the ants cultivate fungal mycelia to strengthen their hunting galleries.

  14. Torrubiellone E, an antimalarial N-hydroxypyridone alkaloid from the spider pathogenic fungus Torrubiella longissima BCC 2022.

    Science.gov (United States)

    Isaka, Masahiko; Haritakun, Rachada; Intereya, Kamolphan; Thanakitpipattana, Donnaya; Hywel-Jones, Nigel L

    2014-05-01

    Torrubiellone E (1), a new N-hydroxypyridone alkaloid, was isolated from the spider pathogenic fungus Torrubiella longissima BCC 2022, together with the known compounds, torrubiellones A (2) and B (3), and JBIR-130 (4). Compound 1 exhibited antimalarial activity against Plasmodium falciparum K1 with an IC5 value of 3.2 microg/mL, while it also showed weak cytotoxic activities.

  15. The Genetic and Molecular Basis of Plant Resistance to Pathogens

    Institute of Scientific and Technical Information of China (English)

    Yan Zhang; Thomas Lubberstedt; Mingliang Xu

    2013-01-01

    Plant pathogens have evolved numerous strategies to obtain nutritive materials from their host,and plants in turn have evolved the preformed physical and chemical barriers as well as sophisticated two-tiered immune system to combat pathogen attacks.Genetically,plant resistance to pathogens can be divided into qualitative and quantitative disease resistance,conditioned by major gene(s) and multiple genes with minor effects,respectively.Qualitative disease resistance has been mostly detected in plant defense against biotrophic pathogens,whereas quantitative disease resistance is involved in defense response to all plant pathogens,from biotrophs,hemibiotrophs to necrotrophs.Plant resistance is achieved through interception of pathogen-derived effectors and elicitation of defense response.In recent years,great progress has been made related to the molecular basis underlying host-pathogen interactions.In this review,we would like to provide an update on genetic and molecular aspects of plant resistance to pathogens.

  16. BIOTRANSFORMATION OF 2,4,6-TRINITROTOLUENE (TNT) BY A PLANT-ASSOCIATED FUNGUS FUSARIUM OXYSPORUM

    Science.gov (United States)

    The capability of a plant-associated fungus, Fusarium oxyvorum, to transform TNT in liquid cultures was investigated. TNT was transformed into 2-amino-4, 6-dinitrotoluene (2-A-DNT), 4-amino-2, 6-dinitrotoluene (4-A- DNT), and 2, 4-diamino-6-nitrotoluene (2, 4-DAT) via 2- and 4-hy...

  17. BIOTRANSFORMATION OF 2,4,6-TRINITROTOLUENE (TNT) BY A PLANT-ASSOCIATED FUNGUS FUSARIUM OXYSPORUM

    Science.gov (United States)

    The capability of a plant-associated fungus, Fusarium oxyvorum, to transform TNT in liquid cultures was investigated. TNT was transformed into 2-amino-4, 6-dinitrotoluene (2-A-DNT), 4-amino-2, 6-dinitrotoluene (4-A- DNT), and 2, 4-diamino-6-nitrotoluene (2, 4-DAT) via 2- and 4-hy...

  18. Leaf-cutter ant fungus gardens are biphasic mixed microbial bioreactors that convert plant biomass to polyols with biotechnological applications.

    Science.gov (United States)

    Somera, Alexandre F; Lima, Adriel M; Dos Santos-Neto, Álvaro J; Lanças, Fernando M; Bacci, Maurício

    2015-07-01

    Leaf-cutter ants use plant matter to culture the obligate mutualistic basidiomycete Leucoagaricus gongylophorus. This fungus mediates ant nutrition on plant resources. Furthermore, other microbes living in the fungus garden might also contribute to plant digestion. The fungus garden comprises a young sector with recently incorporated leaf fragments and an old sector with partially digested plant matter. Here, we show that the young and old sectors of the grass-cutter Atta bisphaerica fungus garden operate as a biphasic solid-state mixed fermenting system. An initial plant digestion phase occurred in the young sector in the fungus garden periphery, with prevailing hemicellulose and starch degradation into arabinose, mannose, xylose, and glucose. These products support fast microbial growth but were mostly converted into four polyols. Three polyols, mannitol, arabitol, and inositol, were secreted by L. gongylophorus, and a fourth polyol, sorbitol, was likely secreted by another, unidentified, microbe. A second plant digestion phase occurred in the old sector, located in the fungus garden core, comprising stocks of microbial biomass growing slowly on monosaccharides and polyols. This biphasic operation was efficient in mediating symbiotic nutrition on plant matter: the microbes, accounting for 4% of the fungus garden biomass, converted plant matter biomass into monosaccharides and polyols, which were completely consumed by the resident ants and microbes. However, when consumption was inhibited through laboratory manipulation, most of the plant polysaccharides were degraded, products rapidly accumulated, and yields could be preferentially switched between polyols and monosaccharides. This feature might be useful in biotechnology.

  19. Conversion of the pathogenic fungus Colletotrichum magna to a nonpathogenic, endophytic mutualist by gene disruption

    Science.gov (United States)

    Redman, R.S.; Ranson, J.C.; Rodriguez, R.J.

    1999-01-01

    Hygromycin-resistant transformants of the cucurbit pathogen Colletotrichum magna (teleomorph: Glomerella magna) were generated by restriction enzyme-mediated integration (REMI) transformation. A rapid pathogenicity assay involving watermelon (Citrullus lanatus) seedlings was developed and 14,400 REMI transformants were screened and assessed for their ability to cause disease, colonize plant tissues, and confer disease resistance against wild-type C. magna. A total of 176 nonpathogenic REMI mutants capable of colonizing cucurbit plants were isolated and assigned to three groups based on their ability to confer disease resistance: phenotype A, 80 to 100% disease protection; phenotype B, 10 to 65% disease protection; and phenotype C, 0 to 4% disease protection. Molecular and genetic analyses of one REMI mutant (R1) indicated that the nonpathogenic phenotype A resulted from a single-site integration. R1 showed a 1:1 segregation of hygromycin resistance and nonpathogenicity and all hygromycin-resistant progeny were nonpathogenic. The integrated vector and 5.5 kb of flanking fungal genomic DNA were isolated from R1 and designated pGMR1. To verify that pGMR1 contained pathogenicity gene sequences, a wild-type isolate of C. magna was transformed with pGMR1 to induce gene disruptions by homologous integration. Approximately 47% of the pGMR1 transformants expressed phenotype A, indicating homologous integration and gene disruption.

  20. Pathogenic and enzyme activities of the entomopathogenic fungus Tolypocladium cylindrosporum (Ascomycota: Hypocreales from Tierra del Fuego, Argentina

    Directory of Open Access Journals (Sweden)

    Ana C Scorsetti

    2012-06-01

    Full Text Available Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T. cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T. cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4ºC, 12ºC and 24ºC, on different agar media supplemented with the following specific substrates: chitin azure, Tween ® 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4ºC, 12ºC and 24ºC. The suspension was adjusted to a concentration of 1x10 7 conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24°C, the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween® 20 at the lower two incubation temperatures of 4

  1. Pathogenic and enzyme activities of the entomopathogenic fungus Tolypocladium cylindrosporum (Ascomycota: Hypocreales) from Tierra del Fuego, Argentina.

    Science.gov (United States)

    Scorsetti, Ana C; Elíades, Lorena A; Stenglein, Sebastián A; Cabello, Marta N; Pelizza, Sebastián A; Saparrat, Mario C N

    2012-06-01

    Tolypocladium cylindrosporum is an entomopathogenic fungi that has been studied as a biological control agent against insects of several orders. The fungus has been isolated from the soil as well as from insects of the orders Coleoptera, Lepidoptera, Diptera and Hymenoptera. In this study, we analyzed the ability of a strain of T cylindrosporum, isolated from soil samples taken in Tierra del Fuego, Argentina, to produce hydrolytic enzymes, and to study the relationship of those activities to the fungus pathogenicity against pest aphids. We have made the traditional and molecular characterization of this strain of T cylindrosporum. The expression of hydrolase activity in the fungal strain was estimated at three incubation temperatures (4 degreeC, 12 degreeC and 24 degreeC), on different agar media supplemented with the following specific substrates: chitin azure, Tween 20, casein, and urea for chitinase, lipase, protease, and urease activity, respectively. The hydrolytic-enzyme activity was estimated qualitatively according to the presence of a halo of clarification through hydrolase action, besides was expressed semi-quantitatively as the ratio between the hydrolytic-halo and colony diameters. The pathogenicity of the fungus was tested on adults of the aphid Rhopalosiphum padi at three temperatures of incubation (4 degree C, 12 degree C and 24 degree C). The suspension was adjusted to a concentration of 1x10(7) conidia/ml. In pathogenicity assays at seven days post-inoculation, the fungus caused the mortality of adults of Ropalosiphum padi at different temperatures also showed a broad ability to grow on several agar-culture media, supplemented with different carbon sources at the three incubation temperatures tested. Although, the growth was greater with higher incubation temperatures (with maximum levels at 24 degreeC), the fungus reached similar colony diameters after 15 days of incubation on the medium supplemented with Tween 20 at the lower two incubation

  2. Proteomic analysis reveals that iron availability alters the metabolic status of the pathogenic fungus Paracoccidioides brasiliensis.

    Directory of Open Access Journals (Sweden)

    Ana F A Parente

    Full Text Available Paracoccidioides brasiliensis is a thermodimorphic fungus and the causative agent of paracoccidioidomycosis (PCM. The ability of P. brasiliensis to uptake nutrients is fundamental for growth, but a reduction in the availability of iron and other nutrients is a host defense mechanism many pathogenic fungi must overcome. Thus, fungal mechanisms that scavenge iron from host may contribute to P. brasiliensis virulence. In order to better understand how P. brasiliensis adapts to iron starvation in the host we compared the two-dimensional (2D gel protein profile of yeast cells during iron starvation to that of iron rich condition. Protein spots were selected for comparative analysis based on the protein staining intensity as determined by image analysis. A total of 1752 protein spots were selected for comparison, and a total of 274 out of the 1752 protein spots were determined to have changed significantly in abundance due to iron depletion. Ninety six of the 274 proteins were grouped into the following functional categories; energy, metabolism, cell rescue, virulence, cell cycle, protein synthesis, protein fate, transcription, cellular communication, and cell fate. A correlation between protein and transcript levels was also discovered using quantitative RT-PCR analysis from RNA obtained from P. brasiliensis under iron restricting conditions and from yeast cells isolated from infected mouse spleens. In addition, western blot analysis and enzyme activity assays validated the differential regulation of proteins identified by 2-D gel analysis. We observed an increase in glycolytic pathway protein regulation while tricarboxylic acid cycle, glyoxylate and methylcitrate cycles, and electron transport chain proteins decreased in abundance under iron limiting conditions. These data suggest a remodeling of P. brasiliensis metabolism by prioritizing iron independent pathways.

  3. Structural characterization of a ribose-5-phosphate isomerase B from the pathogenic fungus Coccidioides immitis

    Directory of Open Access Journals (Sweden)

    Leibly David J

    2011-10-01

    Full Text Available Abstract Background Ribose-5-phosphate isomerase is an enzyme that catalyzes the interconversion of ribose-5-phosphate and ribulose-5-phosphate. This family of enzymes naturally occurs in two distinct classes, RpiA and RpiB, which play an important role in the pentose phosphate pathway and nucleotide and co-factor biogenesis. Results Although RpiB occurs predominantly in bacteria, here we report crystal structures of a putative RpiB from the pathogenic fungus Coccidioides immitis. A 1.9 Å resolution apo structure was solved by combined molecular replacement and single wavelength anomalous dispersion (SAD phasing using a crystal soaked briefly in a solution containing a high concentration of iodide ions. RpiB from C. immitis contains modest sequence and high structural homology to other known RpiB structures. A 1.8 Å resolution phosphate-bound structure demonstrates phosphate recognition and charge stabilization by a single positively charged residue whereas other members of this family use up to five positively charged residues to contact the phosphate of ribose-5-phosphate. A 1.7 Å resolution structure was obtained in which the catalytic base of C. immitis RpiB, Cys76, appears to form a weakly covalent bond with the central carbon of malonic acid with a bond distance of 2.2 Å. This interaction may mimic that formed by the suicide inhibitor iodoacetic acid with RpiB. Conclusion The C. immitis RpiB contains the same fold and similar features as other members of this class of enzymes such as a highly reactive active site cysteine residue, but utilizes a divergent phosphate recognition strategy and may recognize a different substrate altogether.

  4. The pathogenic fungus Paracoccidioides brasiliensis exports extracellular vesicles containing highly immunogenic α-Galactosyl epitopes.

    Science.gov (United States)

    Vallejo, Milene C; Matsuo, Alisson L; Ganiko, Luciane; Medeiros, Lia C Soares; Miranda, Kildare; Silva, Luiz S; Freymüller-Haapalainen, Edna; Sinigaglia-Coimbra, Rita; Almeida, Igor C; Puccia, Rosana

    2011-03-01

    Exosome-like vesicles containing virulence factors, enzymes, and antigens have recently been characterized in fungal pathogens, such as Cryptococcus neoformans and Histoplasma capsulatum. Here, we describe extracellular vesicles carrying highly immunogenic α-linked galactopyranosyl (α-Gal) epitopes in Paracoccidioides brasiliensis. P. brasiliensis is a dimorphic fungus that causes human paracoccidioidomycosis (PCM). For vesicle preparations, cell-free supernatant fluids from yeast cells cultivated in Ham's defined medium-glucose were concentrated in an Amicon ultrafiltration system and ultracentrifuged at 100,000 × g. P. brasiliensis antigens were present in preparations from phylogenetically distinct isolates Pb18 and Pb3, as observed in immunoblots revealed with sera from PCM patients. In an enzyme-linked immunosorbent assay (ELISA), vesicle components containing α-Gal epitopes reacted strongly with anti-α-Gal antibodies isolated from both Chagas' disease and PCM patients, with Marasmius oreades agglutinin (MOA) (a lectin that recognizes terminal α-Gal), but only faintly with natural anti-α-Gal. Reactivity was inhibited after treatment with α-galactosidase. Vesicle preparations analyzed by electron microscopy showed vesicular structures of 20 to 200 nm that were labeled both on the surface and in the lumen with MOA. In P. brasiliensis cells, components carrying α-Gal epitopes were found distributed on the cell wall, following a punctuated confocal pattern, and inside large intracellular vacuoles. Lipid-free vesicle fractions reacted with anti-α-Gal in ELISA only when not digested with α-galactosidase, while reactivity with glycoproteins was reduced after β-elimination, which is indicative of partial O-linked chain localization. Our findings open new areas to explore in terms of host-parasite relationships in PCM and the role played in vivo by vesicle components and α-galactosyl epitopes.

  5. Effects of Pesticide Mixtures on Host-Pathogen Dynamics of the Amphibian Chytrid Fungus.

    Science.gov (United States)

    Buck, Julia C; Hua, Jessica; Brogan, William R; Dang, Trang D; Urbina, Jenny; Bendis, Randall J; Stoler, Aaron B; Blaustein, Andrew R; Relyea, Rick A

    2015-01-01

    Anthropogenic and natural stressors often interact to affect organisms. Amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. Although these factors often co-occur, their effects on amphibians are usually examined in isolation. We hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susceptibility to the fungus Batrachochytrium dendrobatidis (Bd), a pathogen that has contributed to amphibian population declines worldwide. We exposed five anuran species (Pacific treefrog, Pseudacris regilla; spring peeper, Pseudacris crucifer; Cascades frog, Rana cascadae; northern leopard frog, Lithobates pipiens; and western toad, Anaxyrus boreas) from three families to mixtures of four common insecticides (chlorpyrifos, carbaryl, permethrin, and endosulfan) or herbicides (glyphosate, acetochlor, atrazine, and 2,4-D) or a control treatment, either as tadpoles or as newly metamorphic individuals (metamorphs). Subsequently, we exposed animals to Bd or a control inoculate after metamorphosis and compared survival and Bd load. Bd exposure significantly increased mortality in Pacific treefrogs, spring peepers, and western toads, but not in Cascades frogs or northern leopard frogs. However, the effects of pesticide exposure on mortality were negligible, regardless of the timing of exposure. Bd load varied considerably across species; Pacific treefrogs, spring peepers, and western toads had the highest loads, whereas Cascades frogs and northern leopard frogs had the lowest loads. The influence of pesticide exposure on Bd load depended on the amphibian species, timing of pesticide exposure, and the particular pesticide treatment. Our results suggest that exposure to realistic pesticide concentrations has minimal effects on Bd-induced mortality, but can alter Bd load. This result

  6. Whole genome evaluation of horizontal transfers in the pathogenic fungus Aspergillus fumigatus

    Directory of Open Access Journals (Sweden)

    Deschavanne Patrick

    2010-03-01

    Full Text Available Abstract Background Numerous cases of horizontal transfers (HTs have been described for eukaryote genomes, but in contrast to prokaryote genomes, no whole genome evaluation of HTs has been carried out. This is mainly due to a lack of parametric methods specially designed to take the intrinsic heterogeneity of eukaryote genomes into account. We applied a simple and tested method based on local variations of genomic signatures to analyze the genome of the pathogenic fungus Aspergillus fumigatus. Results We detected 189 atypical regions containing 214 genes, accounting for about 1 Mb of DNA sequences. However, the fraction of atypical DNA detected was smaller than the average amount detected in the same conditions in prokaryote genomes (3.1% vs 5.6%. It appeared that about one third of these regions contained no annotated genes, a proportion far greater than in prokaryote genomes. When analyzing the origin of these HTs by comparing their signatures to a home made database of species signatures, 3 groups of donor species emerged: bacteria (40%, fungi (25%, and viruses (22%. It is to be noticed that though inter-domain exchanges are confirmed, we only put in evidence very few exchanges between eukaryotic kingdoms. Conclusions In conclusion, we demonstrated that HTs are not negligible in eukaryote genomes, bearing in mind that in our stringent conditions this amount is a floor value, though of a lesser extent than in prokaryote genomes. The biological mechanisms underlying those transfers remain to be elucidated as well as the biological functions of the transferred genes.

  7. Climate forcing of an emerging pathogenic fungus across a montane multi-host community.

    Science.gov (United States)

    Clare, Frances C; Halder, Julia B; Daniel, Olivia; Bielby, Jon; Semenov, Mikhail A; Jombart, Thibaut; Loyau, Adeline; Schmeller, Dirk S; Cunningham, Andrew A; Rowcliffe, Marcus; Garner, Trenton W J; Bosch, Jaime; Fisher, Matthew C

    2016-12-05

    Changes in the timings of seasonality as a result of anthropogenic climate change are predicted to occur over the coming decades. While this is expected to have widespread impacts on the dynamics of infectious disease through environmental forcing, empirical data are lacking. Here, we investigated whether seasonality, specifically the timing of spring ice-thaw, affected susceptibility to infection by the emerging pathogenic fungus Batrachochytrium dendrobatidis (Bd) across a montane community of amphibians that are suffering declines and extirpations as a consequence of this infection. We found a robust temporal association between the timing of the spring thaw and Bd infection in two host species, where we show that an early onset of spring forced high prevalences of infection. A third highly susceptible species (the midwife toad, Alytes obstetricans) maintained a high prevalence of infection independent of time of spring thaw. Our data show that perennially overwintering midwife toad larvae may act as a year-round reservoir of infection with variation in time of spring thaw determining the extent to which infection spills over into sympatric species. We used future temperature projections based on global climate models to demonstrate that the timing of spring thaw in this region will advance markedly by the 2050s, indicating that climate change will further force the severity of infection. Our findings on the effect of annual variability on multi-host infection dynamics show that the community-level impact of fungal infectious disease on biodiversity will need to be re-evaluated in the face of climate change.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'. © 2016 The Authors.

  8. Effects of Pesticide Mixtures on Host-Pathogen Dynamics of the Amphibian Chytrid Fungus.

    Directory of Open Access Journals (Sweden)

    Julia C Buck

    Full Text Available Anthropogenic and natural stressors often interact to affect organisms. Amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. Although these factors often co-occur, their effects on amphibians are usually examined in isolation. We hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susceptibility to the fungus Batrachochytrium dendrobatidis (Bd, a pathogen that has contributed to amphibian population declines worldwide. We exposed five anuran species (Pacific treefrog, Pseudacris regilla; spring peeper, Pseudacris crucifer; Cascades frog, Rana cascadae; northern leopard frog, Lithobates pipiens; and western toad, Anaxyrus boreas from three families to mixtures of four common insecticides (chlorpyrifos, carbaryl, permethrin, and endosulfan or herbicides (glyphosate, acetochlor, atrazine, and 2,4-D or a control treatment, either as tadpoles or as newly metamorphic individuals (metamorphs. Subsequently, we exposed animals to Bd or a control inoculate after metamorphosis and compared survival and Bd load. Bd exposure significantly increased mortality in Pacific treefrogs, spring peepers, and western toads, but not in Cascades frogs or northern leopard frogs. However, the effects of pesticide exposure on mortality were negligible, regardless of the timing of exposure. Bd load varied considerably across species; Pacific treefrogs, spring peepers, and western toads had the highest loads, whereas Cascades frogs and northern leopard frogs had the lowest loads. The influence of pesticide exposure on Bd load depended on the amphibian species, timing of pesticide exposure, and the particular pesticide treatment. Our results suggest that exposure to realistic pesticide concentrations has minimal effects on Bd-induced mortality, but can alter Bd load

  9. Climate forcing of an emerging pathogenic fungus across a montane multi-host community

    Science.gov (United States)

    Clare, Frances C.; Halder, Julia B.; Daniel, Olivia; Bielby, Jon; Semenov, Mikhail A.; Jombart, Thibaut; Loyau, Adeline; Schmeller, Dirk S.; Cunningham, Andrew A.; Rowcliffe, Marcus; Bosch, Jaime

    2016-01-01

    Changes in the timings of seasonality as a result of anthropogenic climate change are predicted to occur over the coming decades. While this is expected to have widespread impacts on the dynamics of infectious disease through environmental forcing, empirical data are lacking. Here, we investigated whether seasonality, specifically the timing of spring ice-thaw, affected susceptibility to infection by the emerging pathogenic fungus Batrachochytrium dendrobatidis (Bd) across a montane community of amphibians that are suffering declines and extirpations as a consequence of this infection. We found a robust temporal association between the timing of the spring thaw and Bd infection in two host species, where we show that an early onset of spring forced high prevalences of infection. A third highly susceptible species (the midwife toad, Alytes obstetricans) maintained a high prevalence of infection independent of time of spring thaw. Our data show that perennially overwintering midwife toad larvae may act as a year-round reservoir of infection with variation in time of spring thaw determining the extent to which infection spills over into sympatric species. We used future temperature projections based on global climate models to demonstrate that the timing of spring thaw in this region will advance markedly by the 2050s, indicating that climate change will further force the severity of infection. Our findings on the effect of annual variability on multi-host infection dynamics show that the community-level impact of fungal infectious disease on biodiversity will need to be re-evaluated in the face of climate change. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’. PMID:28080980

  10. The dynamics of plant cell-wall polysaccharide decomposition in leaf-cutting ant fungus gardens

    DEFF Research Database (Denmark)

    Moller, Isabel Eva; de Fine Licht, Henrik Hjarvard; Harholt, Jesper;

    2011-01-01

    communities of microbial and invertebrate symbionts have evolved associations with the dump material from leaf-cutting ant nests, to exploit decomposition niches that the ant garden-fungus does not utilize. Our approach thus provides detailed insight into the nutritional benefits and shortcomings associated......The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus......, to map the occurrence of cell wall polymers in consecutive sections of the fungus garden of the leaf-cutting ant Acromyrmex echinatior. We show that pectin, xyloglucan and some xylan epitopes are degraded, whereas more highly substituted xylan and cellulose epitopes remain as residuals in the waste...

  11. Plant signalling components EDS1 and SGT1 enhance disease caused by the necrotrophic pathogen Botrytis cinerea.

    Science.gov (United States)

    El Oirdi, Mohamed; Bouarab, Kamal

    2007-01-01

    * Botrytis cinerea is a necrotrophic fungus that causes grey mould on a wide range of food plants, especially grapevine, tomato, soft fruits and vegetables. This disease brings about important economic losses in both pre- and postharvest crops. Successful protection of host plants against this pathogen is severely hampered by a lack of resistance genes in the hosts and the considerable phenotypic diversity of the fungus. * The aim of this study was to test whether B. cinerea manipulates the immunity-signalling pathways in plants to restore its disease. * We showed that B. cinerea caused disease in Nicotiana benthamiana through the activation of two plant signalling genes, EDS1 and SGT1, which have been shown to be essential for resistance against biotrophic pathogens; and more interestingly, virus-induced gene silencing of these two plant signalling components enhanced N. benthamiana resistance to B. cinerea. Finally, plants expressing the baculovirus antiapoptotic protein p35 were more resistant to this necrotrophic pathogen than wild-type plants. * This work highlights a new strategy used by B. cinerea to establish disease. This information is important for the design of strategies to improve plant pathogen resistance.

  12. Biological activity of the mite Sancassania sp. (Acari: Acaridae from bat guano associated with the pathogenic fungus Histoplasma capsulatum

    Directory of Open Access Journals (Sweden)

    Daniel A Estrada-Bárcenas

    2010-03-01

    Full Text Available Mites and the mammal pathogenic fungus Histoplasma capsulatum are the major components of bat guano microbiota. Interactions between mites and H. capsulatum were evaluated under laboratory conditions. Acarid mites, mainly Sancassania sp., were the most abundant microarthropod in the sampled guano of the Mexican bat Tadarida brasiliensis mexicana and, based on its morphology, Sancassania sp. was similar to the cosmopolitan species Sancassania sphaerogaster. The mycophagous and vectoring activities of this mite were tested for H. capsulatum and two other fungal species, Sporothrix schenckii (pathogenic and Aspergillus sclerotiorum (non-pathogenic. S. ca. sphaerogaster was able to reproduce in H. capsulatum and S. schenckii colonies, multiplying in great numbers under controlled fungal mycelial-phase culture conditions. H. capsulatum colonies were completely destroyed after 14 days of in vitro interaction with mites. In contrast, S. ca. sphaerogaster did not reproduce in A. sclerotiorum cultures. S. ca. sphaerogaster was found vectoring H. capsulatum, but not the two other fungal species studied.

  13. One fungus, one name promotes progressive plant pathology

    NARCIS (Netherlands)

    Wingfield, M.J.; Beer, de Z.W.; Slippers, B.; Wingfield, B.D.; Groenewald, J.Z.; Lombard, L.; Crous, P.W.

    2012-01-01

    The robust and reliable identification of fungi underpins virtually every element of plant pathology, from disease diagnosis to studies of biology, management/control, quarantine and, even more recently, comparative genomics. Most plant diseases are caused by fungi, typically pleomorphic organisms,

  14. One fungus, one name promotes progressive plant pathology

    NARCIS (Netherlands)

    Wingfield, M.J.; De Beer, Z.W.; Slippers, B.; Wingfield, B.D.; Groenewald, J.Z.; Lombard, L.; Crous, P.W.

    2011-01-01

    The robust and reliable identification of fungi underpins virtually every element of plant pathology, from disease diagnosis to studies of biology, management/control, quarantine and, even more recently, comparative genomics. Most plant diseases are caused by fungi, typically pleomorphic organisms,

  15. One fungus, one name promotes progressive plant pathology

    NARCIS (Netherlands)

    Wingfield, M.J.; Beer, de Z.W.; Slippers, B.; Wingfield, B.D.; Groenewald, J.Z.; Lombard, L.; Crous, P.W.

    2012-01-01

    The robust and reliable identification of fungi underpins virtually every element of plant pathology, from disease diagnosis to studies of biology, management/control, quarantine and, even more recently, comparative genomics. Most plant diseases are caused by fungi, typically pleomorphic organisms,

  16. One fungus, one name promotes progressive plant pathology

    NARCIS (Netherlands)

    Wingfield, M.J.; De Beer, Z.W.; Slippers, B.; Wingfield, B.D.; Groenewald, J.Z.; Lombard, L.; Crous, P.W.

    2011-01-01

    The robust and reliable identification of fungi underpins virtually every element of plant pathology, from disease diagnosis to studies of biology, management/control, quarantine and, even more recently, comparative genomics. Most plant diseases are caused by fungi, typically pleomorphic organisms,

  17. The rhizosphere microbiome: significance of plant beneficial, plant pathogenic, and human pathogenic microorganisms.

    Science.gov (United States)

    Mendes, Rodrigo; Garbeva, Paolina; Raaijmakers, Jos M

    2013-09-01

    Microbial communities play a pivotal role in the functioning of plants by influencing their physiology and development. While many members of the rhizosphere microbiome are beneficial to plant growth, also plant pathogenic microorganisms colonize the rhizosphere striving to break through the protective microbial shield and to overcome the innate plant defense mechanisms in order to cause disease. A third group of microorganisms that can be found in the rhizosphere are the true and opportunistic human pathogenic bacteria, which can be carried on or in plant tissue and may cause disease when introduced into debilitated humans. Although the importance of the rhizosphere microbiome for plant growth has been widely recognized, for the vast majority of rhizosphere microorganisms no knowledge exists. To enhance plant growth and health, it is essential to know which microorganism is present in the rhizosphere microbiome and what they are doing. Here, we review the main functions of rhizosphere microorganisms and how they impact on health and disease. We discuss the mechanisms involved in the multitrophic interactions and chemical dialogues that occur in the rhizosphere. Finally, we highlight several strategies to redirect or reshape the rhizosphere microbiome in favor of microorganisms that are beneficial to plant growth and health. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  18. Lutein, a Natural Carotenoid, Induces α-1,3-Glucan Accumulation on the Cell Wall Surface of Fungal Plant Pathogens

    Directory of Open Access Journals (Sweden)

    Junnosuke Otaka

    2016-07-01

    Full Text Available α-1,3-Glucan, a component of the fungal cell wall, is a refractory polysaccharide for most plants. Previously, we showed that various fungal plant pathogens masked their cell wall surfaces with α-1,3-glucan to evade plant immunity. This surface accumulation of α-1,3-glucan was infection specific, suggesting that plant factors might induce its production in fungi. Through immunofluorescence observations of fungal cell walls, we found that carrot (Daucus carota extract induced the accumulation of α-1,3-glucan on germlings in Colletotrichum fioriniae, a polyphagous fungal pathogen that causes anthracnose disease in various dicot plants. Bioassay-guided fractionation of carrot leaf extract successfully identified two active substances that caused α-1,3-glucan accumulation in this fungus: lutein, a carotenoid widely distributed in plants, and stigmasterol, a plant-specific membrane component. Lutein, which had a greater effect on C. fioriniae, also induced α-1,3-glucan accumulation in other Colletotrichum species and in the phylogenetically distant rice pathogen Cochliobolus miyabeanus, but not in the rice pathogen Magnaporthe oryzae belonging to the same phylogenetic subclass as Colletotrichum. Our results suggested that fungal plant pathogens reorganize their cell wall components in response to specific plant-derived compounds, which these pathogens may encounter during infection.

  19. The ability to cause infection in a pathogenic fungus uncovers a new biological feature of honey bee viruses.

    Science.gov (United States)

    Li, Zhiguo; Su, Songkun; Hamilton, Michele; Yan, Limin; Chen, Yanping

    2014-07-01

    We demonstrated that honey bee viruses including Deformed wing virus (DWV), Black queen cell virus (BQCV) and Israeli acute paralysis virus (IAPV) could infect and replicate in the fungal pathogen Ascosphaera apis that causes honey bee chalkbrood disease, revealing a novel biological feature of honey bee viruses. The phylogenetic analysis show that viruses of fungal and honey bee origins form two clusters in the phylogenetic trees distinctly and that host range of honey bee viruses is dynamic. Further studies are warranted to investigate the impact of the viruses on the fitness of their fungal host and phenotypic effects the virus-fungus combination has on honey bee hosts. Published by Elsevier Inc.

  20. Uncovering plant-pathogen crosstalk through apoplastic proteomic studies

    Directory of Open Access Journals (Sweden)

    Bertrand eDelaunois

    2014-06-01

    Full Text Available Plant pathogens have evolved by developing different strategies to infect their host, which in turn have elaborated immune responses to counter the pathogen invasion. The apoplast, including the cell wall and extracellular space outside the plasma membrane, is one of the first compartments where pathogen-host interaction occurs. The plant cell wall is composed of a complex network of polysaccharides polymers and glycoproteins and serves as a natural physical barrier against pathogen invasion. The apoplastic fluid, circulating through the cell wall and intercellular spaces, provides a means for delivering molecules and facilitating intercellular communications. Some plant-pathogen interactions lead to plant cell wall degradation allowing pathogens to penetrate into the cells. In turn, the plant immune system recognizes microbial- or damage-associated molecular patterns (MAMPs or DAMPs and initiates a set of basal immune responses, including the strengthening of the plant cell wall. The establishment of defense requires the regulation of a wide variety of proteins that are involved at different levels, from receptor perception of the pathogen via signaling mechanisms to the strengthening of the cell wall or degradation of the pathogen itself. A fine regulation of apoplastic proteins is therefore essential for rapid and effective pathogen perception and for maintaining cell wall integrity. This review aims to provide insight into analyses using proteomic approaches of the apoplast to highlight the modulation of the apoplastic protein patterns during pathogen infection and to unravel the key players involved in plant-pathogen interaction.

  1. Biscopyran, a phytotoxic hexasubstituted pyranopyran produced by Biscogniauxia mediterranea, a fungus pathogen of cork oak.

    Science.gov (United States)

    Evidente, Antonio; Andolfi, Anna; Maddau, Lucia; Franceschini, Antonio; Marras, Francesco

    2005-04-01

    A new phytotoxic hexasubstituted pyranopyran, biscopyran (3), was isolated together with phenylacetic acid (2) and previously isolated 5-methylmellein (1) from the liquid culture filtrates of Biscogniauxiamediterranea, a major fungal pathogen involved in oak decline in Sardinia. Biscopyran was characterized by spectroscopic methods as a new (Z)-2-methoxy-1-[7-((Z)-2-methoxybut-2-enoyl)-3,4,5,6-tetramethyl-2H,7H-pyrano[2,3-b]pyran-2-yl]but-2-en-1-one. Biscopyran assayed at 0.26-0.026 mM concentration range caused epinasty on cork oak cuttings. On a nonhost plant, tomato, biscopyran caused wilting. Phenylacetic acid, assayed at the same concentration, was toxic to Q. suber, while on tomato cuttings it induced internal tissue collapse on the stem.

  2. The effects of microgravity and clinorotation on the interaction of plant cells with fungal pathogen

    Science.gov (United States)

    Nedukha, O.; Kordyum, E.; Leach, J.; Martyn, G.; Ryba-White, M.

    The influence of microgravity and slow horizontal clinorotation (2 rev/min), which partly mimics microgravity, on the interaction of plant cells of soybean roots to Phytophthora sojae and of potato minitubers to Phytophthora infestans was studied during the Space Shuttle Mission STS-87 and during clinorotation. Seedlings of soybean cultivar Williams 82 grown in spaceflight and at 1 g were untreated or inoculated with pathogen P. sojae; minitubers of potato (cv Adreta) grown at horizontal clinorotation and the vertical control also were untreated or inoculated with pathogen P. infestans. The methods of light microscopy, scanning and transmission electron microscopy, confocal microscopy and also cytochemistry for the determination of callose content and peroxydase activity were used in the experiments. Post-landing analysis of the meristem cells of soybean roots infected with P. sojae and post-clinorotation analysis of the parenchyma cells of potato minitubers cells infected with P. infestans showed more destroying symptoms in cells of plant-host, which were more extensive colonized relative to the controls exposed to the pathogen fungus. Infected cells of plants-host were divided in two types: cells of first type were completely destroyed and hyphae of pathogen fungus were into these cells or in intercellular spaces; cells of second type characterized by partly changed ultrastructure and a calcium sites were contained above in mentioned cells. These data suggest that root cells of soybean seedlings grown in microgravity and cells of potato minitubers grown at slow horizontal clinorotation are more susceptible to penetration of a fungal pathogen in comparison with the corresponding controls.

  3. Spread of plant pathogens and insect vectors at the northern range margin of cypress in Italy

    Science.gov (United States)

    Zocca, Alessia; Zanini, Corrado; Aimi, Andrea; Frigimelica, Gabriella; La Porta, Nicola; Battisti, Andrea

    2008-05-01

    The Mediterranean cypress ( Cupressus sempervirens) is a multi-purpose tree widely used in the Mediterranean region. An anthropogenic range expansion of cypress has taken place at the northern margin of the range in Italy in recent decades, driven by ornamental planting in spite of climatic constraints imposed by low winter temperature. The expansion has created new habitats for pathogens and pests, which strongly limit tree survival in the historical (core) part of the range. Based on the enemy release hypothesis, we predicted that damage should be lower in the expansion area. By comparing tree and seed cone damage by pathogens and pests in core and expansion areas of Trentino, a district in the southern Alps, we showed that tree damage was significantly higher in the core area. Seed cones of C. sempervirens are intensively colonized by an aggressive and specific pathogen (the canker fungus Seiridium cardinale, Coelomycetes), associated with seed insect vectors Megastigmus wachtli (Hymenoptera Torymidae) and Orsillus maculatus (Heteroptera Lygaeidae). In contrast, we observed lower tree damage in the expansion area, where a non-aggressive fungus ( Pestalotiopsis funerea, Coelomycetes) was more frequently associated with the same insect vectors. Our results indicate that both insect species have a great potential to reach the range margin, representing a continuous threat of the arrival of fungal pathogens to trees planted at extreme sites. Global warming may accelerate this process since both insects and fungi profit from increased temperature. In the future, cypress planted at the range margin may then face similar pest and pathogen threats as in the historical range.

  4. Polyketides from the plant endophytic fungus Cladosporium sp. IFB3lp-2.

    Science.gov (United States)

    Wuringege; Guo, Zhi-Kai; Wei, Wei; Jiao, Rui-Hua; Yan, Tong; Zang, Le-Yun; Jiang, Rong; Tan, Ren-Xiang; Ge, Hui-Ming

    2013-09-01

    Chemical study of the ethyl acetate extract of the plant endophytic fungus Cladosporium sp. (strain no. IFB3lp-2) yielded three new polyketides (1-3), together with nine known compounds. All of the structures were elucidated on the basis of spectroscopic methods. The isolated compounds were screened for their cytotoxic, antiviral, and acetyl cholinesterase inhibitory activities. Regretfully, no compounds showed any significant activity in these assays.

  5. The Dynamics of Plant Cell-Wall Polysaccharide Decomposition in Leaf-Cutting Ant Fungus Gardens

    OpenAIRE

    Moller, Isabel E.; De Fine Licht, Henrik H; Jesper Harholt; Willats, William G. T; Boomsma, Jacobus J.

    2011-01-01

    The degradation of live plant biomass in fungus gardens of leaf-cutting ants is poorly characterised but fundamental for understanding the mutual advantages and efficiency of this obligate nutritional symbiosis. Controversies about the extent to which the garden-symbiont Leucocoprinus gongylophorus degrades cellulose have hampered our understanding of the selection forces that induced large scale herbivory and of the ensuing ecological footprint of these ants. Here we use a recently establish...

  6. Relative importance of an arbuscular mycorrhizal fungus (Rhizophagus intraradices) and root hairs in plant drought tolerance.

    Science.gov (United States)

    Li, Tao; Lin, Ge; Zhang, Xin; Chen, Yongliang; Zhang, Shubin; Chen, Baodong

    2014-11-01

    Both arbuscular mycorrhizal (AM) fungi and root hairs play important roles in plant uptake of water and mineral nutrients. To reveal the relative importance of mycorrhiza and root hairs in plant water relations, a bald root barley (brb) mutant and its wild type (wt) were grown with or without inoculation of the AM fungus Rhizophagus intraradices under well-watered or drought conditions, and plant physiological traits relevant to drought stress resistance were recorded. The experimental results indicated that the AM fungus could almost compensate for the absence of root hairs under drought-stressed conditions. Moreover, phosphorus (P) concentration, leaf water potential, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency were significantly increased by R. intraradices but not by root hairs, except for shoot P concentration and photosynthetic rate under the drought condition. Root hairs even significantly decreased root P concentration under drought stresses. These results confirm that AM fungi can enhance plant drought tolerance by improvement of P uptake and plant water relations, which subsequently promote plant photosynthetic performance and growth, while root hairs presumably contribute to the improvement of plant growth and photosynthetic capacity through an increase in shoot P concentration.

  7. A chitin synthase with a myosin-like motor domain is essential for hyphal growth, appressorium differentiation, and pathogenicity of the maize anthracnose fungus Colletotrichum graminicola.

    Science.gov (United States)

    Werner, Stefan; Sugui, Janyce A; Steinberg, Gero; Deising, Holger B

    2007-12-01

    Chitin synthesis contributes to cell wall biogenesis and is essential for invasion of solid substrata and pathogenicity of filamentous fungi. In contrast to yeasts, filamentous fungi contain up to 10 chitin synthases (CHS), which might reflect overlapping functions and indicate their complex lifestyle. Previous studies have shown that a class VI CHS of the maize anthracnose fungus Colletotrichum graminicola is essential for cell wall synthesis of conidia and vegetative hyphae. Here, we report on cloning and characterization of three additional CHS genes, CgChsI, CgChsIII, and CgChsV, encoding class I, III, and V CHS, respectively. All CHS genes are expressed during vegetative and pathogenic development. DeltaCgChsI and DeltaCgChsIII mutants did not differ significantly from the wild-type isolate with respect to hyphal growth and pathogenicity. In contrast, null mutants in the CgChsV gene, which encodes a CHS with an N-terminal myosin-like motor domain, are strongly impaired in vegetative growth and pathogenicity. Even in osmotically stabilized media, vegetative hyphae of DeltaCgChsV mutants exhibited large balloon-like swellings, appressorial walls appeared to disintegrate during maturation, and infection cells were nonfunctional. Surprisingly, DeltaCgChsV mutants were able to form dome-shaped hyphopodia that exerted force and showed host cell wall penetration rates comparable with the wild type. However, infection hyphae that formed within the plant cells exhibited severe swellings and were not able to proceed with plant colonization efficiently. Consequently, DeltaCgChsV mutants did not develop macroscopically visible anthracnose disease symptoms and, thus, were nonpathogenic.

  8. Molecular profiling and bioactive potential of an endophytic fungus Aspergillus sulphureus isolated from Sida acuta: a medicinal plant.

    Science.gov (United States)

    Murali, M; Mahendra, C; Hema, P; Rajashekar, N; Nataraju, A; Sudarshana, M S; Amruthesh, K N

    2017-12-01

    Sida acuta Burm.f. (Malvaceae) extracts are reported to have applications against malaria, diuretic, antipyretic, nervous and urinary diseases. No fungal endophytes of S. acuta are reported. Isolation, identification and evaluation of antibacterial, antioxidant, anticancer and haemolytic potential of fungal endophytes from the ethnomedcinal plant S. acuta. Sida acuta stem segments were placed on PDA medium to isolate endophytic fungi. The fungus was identified by genomic DNA analysis and phylogenetic tree was constructed using ITS sequences (GenBank) to confirm species. The antibacterial efficacy of Aspergillus sulphureus MME12 ethyl acetate extract was tested against Gram-positive and Gram-negative pathogenic bacteria. DPPH free radical scavenging activity, anticancer and DNA fragmentation against EAC cells, and direct haemolytic activity (100-500 μg/mL) using human erythrocytes were determined. The ethyl acetate extract of A. sulphureus (Fresen.) Wehmer (Trichocomaceae) demonstrated significant antibacterial potential against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhi compared to streptomycin. MIC against test pathogens was in the range of 15.6-62.5 μg/mL. The antioxidant results revealed significant RSA from 12.43% to 62.02% (IC50 = 350.4 μg/mL, p ≤ 0.05). MME12 offered considerable inhibition of EAC proliferation (23% to 84%, IC50 = 216.7 μg/mL, p ≤ 0.05) supported by DNA fragmentation studies. The extract also offered insignificant haemolysis (5.6%) compared to Triton X-100. A single endophytic fungus, A. sulphureus MME12 was isolated and identified using molecular profiling. The above-mentioned findings support the pharmacological application of A. sulphureus MME12 extract and demand for purification of the active principle(s).

  9. Mating and Progeny Isolation in The Corn Smut Fungus Ustilago maydis

    Science.gov (United States)

    The corn smut pathogen, Ustilago maydis (U. maydis) (DC.) Corda, is a semi-obligate plant pathogenic fungus in the phylum Basidiomycota (Alexopoulos, Mims and Blackwell, 1996). The fungus can be easily cultured in its haploid yeast phase on common laboratory media. However, to complete its sexual cy...

  10. Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America

    Science.gov (United States)

    Tara Chestnut; Chauncey Anderson; Radu Popa; Andrew R. Blaustein; Mary Voytek; Deanna H. Olson; Julie. Kirshtein

    2014-01-01

    Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines...

  11. Genome Sequence of Bacillus subtilis MB73/2, a Soil Isolate Inhibiting the Growth of Plant Pathogens Dickeya spp. and Rhizoctonia solani.

    Science.gov (United States)

    Krzyzanowska, Dorota M; Iwanicki, Adam; Ossowicki, Adam; Obuchowski, Michal; Jafra, Sylwia

    2013-05-16

    Bacillus subilis MB73/2 is a Gram-positive bacterium isolated in Poland from a meadow soil sample. When tested in vitro, the strain shows strong antagonism toward plant pathogens-the soft rot-causing bacteria Dickeya spp. and the crown rot fungus Rhizoctonia solani. Here, we present the genome sequence of MB73/2.

  12. Evolution and genome architecture in fungal plant pathogens.

    Science.gov (United States)

    Möller, Mareike; Stukenbrock, Eva H

    2017-08-07

    The fungal kingdom comprises some of the most devastating plant pathogens. Sequencing the genomes of fungal pathogens has shown a remarkable variability in genome size and architecture. Population genomic data enable us to understand the mechanisms and the history of changes in genome size and adaptive evolution in plant pathogens. Although transposable elements predominantly have negative effects on their host, fungal pathogens provide prominent examples of advantageous associations between rapidly evolving transposable elements and virulence genes that cause variation in virulence phenotypes. By providing homogeneous environments at large regional scales, managed ecosystems, such as modern agriculture, can be conducive for the rapid evolution and dispersal of pathogens. In this Review, we summarize key examples from fungal plant pathogen genomics and discuss evolutionary processes in pathogenic fungi in the context of molecular evolution, population genomics and agriculture.

  13. Phosphorylation and proteome dynamics in pathogen-resistant tomato plants

    NARCIS (Netherlands)

    Stulemeijer, I.J.E.

    2008-01-01

    Microbial plant pathogens impose a continuous threat on global food production. Similar to disease resistance in mammals, an innate immune system allows plants to recognise pathogens and swiftly activate defence. For the work described in this thesis, the interaction between tomato and the extracell

  14. Insights into Cross-Kingdom Plant Pathogenic Bacteria

    Directory of Open Access Journals (Sweden)

    Morgan W.B. Kirzinger

    2011-11-01

    Full Text Available Plant and human pathogens have evolved disease factors to successfully exploit their respective hosts. Phytopathogens utilize specific determinants that help to breach reinforced cell walls and manipulate plant physiology to facilitate the disease process, while human pathogens use determinants for exploiting mammalian physiology and overcoming highly developed adaptive immune responses. Emerging research, however, has highlighted the ability of seemingly dedicated human pathogens to cause plant disease, and specialized plant pathogens to cause human disease. Such microbes represent interesting systems for studying the evolution of cross-kingdom pathogenicity, and the benefits and tradeoffs of exploiting multiple hosts with drastically different morphologies and physiologies. This review will explore cross-kingdom pathogenicity, where plants and humans are common hosts. We illustrate that while cross-kingdom pathogenicity appears to be maintained, the directionality of host association (plant to human, or human to plant is difficult to determine. Cross-kingdom human pathogens, and their potential plant reservoirs, have important implications for the emergence of infectious diseases.

  15. Phosphorylation and proteome dynamics in pathogen-resistant tomato plants

    NARCIS (Netherlands)

    Stulemeijer, I.J.E.

    2008-01-01

    Microbial plant pathogens impose a continuous threat on global food production. Similar to disease resistance in mammals, an innate immune system allows plants to recognise pathogens and swiftly activate defence. For the work described in this thesis, the interaction between tomato and the

  16. The top 10 oomycete pathogens in molecular plant pathology

    Science.gov (United States)

    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens that threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant pathogenic oomycete taxa based on scientific and economic importance. In total, ...

  17. Phosphorylation and proteome dynamics in pathogen-resistant tomato plants

    NARCIS (Netherlands)

    Stulemeijer, I.J.E.

    2008-01-01

    Microbial plant pathogens impose a continuous threat on global food production. Similar to disease resistance in mammals, an innate immune system allows plants to recognise pathogens and swiftly activate defence. For the work described in this thesis, the interaction between tomato and the extracell

  18. The Top 10 oomycete pathogens in molecular plant pathology

    NARCIS (Netherlands)

    Kamoun, Sophien; Furzer, Oliver; Jones, Jonathan D G; Judelson, Howard S; Ali, Gul Shad; Dalio, Ronaldo J D; Roy, Sanjoy Guha; Schena, Leonardo; Zambounis, Antonios; Panabières, Franck; Cahill, David; Ruocco, Michelina; Figueiredo, Andreia; Chen, Xiao-Ren; Hulvey, Jon; Stam, Remco; Lamour, Kurt; Gijzen, Mark; Tyler, Brett M; Grünwald, Niklaus J; Mukhtar, M Shahid; Tomé, Daniel F A; Tör, Mahmut; Van Den Ackerveken, Guido; McDowell, John; Daayf, Fouad; Fry, William E; Lindqvist-Kreuze, Hannele; Meijer, Harold J G; Petre, Benjamin; Ristaino, Jean; Yoshida, Kentaro; Birch, Paul R J; Govers, Francine

    2015-01-01

    Oomycetes form a deep lineage of eukaryotic organisms that includes a large number of plant pathogens which threaten natural and managed ecosystems. We undertook a survey to query the community for their ranking of plant-pathogenic oomycete species based on scientific and economic importance. In tot

  19. The Venturia Apple Pathosystem: Pathogenicity Mechanisms and Plant Defense Responses

    Directory of Open Access Journals (Sweden)

    Gopaljee Jha

    2009-01-01

    Full Text Available Venturia inaequalis is the causal agent of apple scab, a devastating disease of apple. We outline several unique features of this pathogen which are useful for molecular genetics studies intended to understand plant-pathogen interactions. The pathogenicity mechanisms of the pathogen and overview of apple defense responses, monogenic and polygenic resistance, and their utilization in scab resistance breeding programs are also reviewed.

  20. Interrelationships of food safety and plant pathology: the life cycle of human pathogens on plants.

    Science.gov (United States)

    Barak, Jeri D; Schroeder, Brenda K

    2012-01-01

    Bacterial food-borne pathogens use plants as vectors between animal hosts, all the while following the life cycle script of plant-associated bacteria. Similar to phytobacteria, Salmonella, pathogenic Escherichia coli, and cross-domain pathogens have a foothold in agricultural production areas. The commonality of environmental contamination translates to contact with plants. Because of the chronic absence of kill steps against human pathogens for fresh produce, arrival on plants leads to persistence and the risk of human illness. Significant research progress is revealing mechanisms used by human pathogens to colonize plants and important biological interactions between and among bacteria in planta. These findings articulate the difficulty of eliminating or reducing the pathogen from plants. The plant itself may be an untapped key to clean produce. This review highlights the life of human pathogens outside an animal host, focusing on the role of plants, and illustrates areas that are ripe for future investigation.

  1. Leucoagaricus gongylophorus Produces Diverse Enzymes for the Degradation of Recalcitrant Plant Polymers in Leaf-Cutter Ant Fungus Gardens

    Energy Technology Data Exchange (ETDEWEB)

    Aylward, Frank O. [Univ. of Wisconsin, Madison, WI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burnum-Johnson, Kristin E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tringe, Susannah G. [Dept. of Energy Joint Genome Inst., Walnut Creek, CA (United States); Teiling, Clotilde [Roche Diagnostics, Indianapolis, IN (United States); Tremmel, Daniel [Univ. of Wisconsin, Madison, WI (United States); Moeller, Joseph [Univ. of Wisconsin, Madison, WI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scott, Jarrod J. [Univ. of Wisconsin, Madison, WI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Barry, Kerrie W. [Dept. of Energy Joint Genome Inst., Walnut Creek, CA (United States); Piehowski, Paul D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nicora, Carrie D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Malfatti, Stephanie [Dept. of Energy Joint Genome Inst., Walnut Creek, CA (United States); Monroe, Matthew E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Purvine, Samuel O. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Goodwin, Lynne A. [Dept. of Energy Joint Genome Inst., Walnut Creek, CA (United States); Smith, Richard D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Weinstock, George [Washington Univ. School of Medicine, St. Louis, MS (United States); Gerardo, Nicole [Emory Univ., Atlanta, GA (United States); Suen, Garret [Dept. of Energy Joint Genome Inst., Walnut Creek, CA (United States); Lipton, Mary S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Currie, Cameron R. [Univ. of Wisconsin, Madison, WI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Smothsonian Tropical Research Inst., Balboa (Panama)

    2013-06-12

    Plants represent a large reservoir of organic carbon comprised largely of recalcitrant polymers that most metazoans are unable to deconstruct. Many herbivores gain access to nutrients in this material indirectly by associating with microbial symbionts, and leaf-cutter ants are a paradigmatic example. These ants use fresh foliar biomass as manure to cultivate fungus gardens composed primarily of Leucoagaricus gongylophorus, a basidiomycetous symbiont that produces specialized hyphal swellings that serve as a food source for the host ant colony. Although leaf-cutter ants are conspicuous herbivores that contribute substantially to carbon turnover in Neotropical ecosystems, the process through which plant biomass is degraded in their fungus gardens is not well understood. Here we present the first draft genome of L. gongylophorus, and using genomic, metaproteomic, and phylogenetic tools we investigate its role in lignocellulose degradation in the fungus gardens of both Atta cephalotes and Acromyrmex echinatior leaf-cutter ants. We show that L. gongylophorus produces a diversity of lignocellulases in fungus gardens, and is likely the primary driver of plant biomass degradation in these ecosystems. We also show that this fungus produces distinct sets of lignocellulases throughout the different stages of biomass degradation, including numerous cellulases and laccases that may be playing an important but previously uncharacterized role in lignocellulose degradation. Our study provides a comprehensive analysis of plant biomass degradation in leaf-cutter ant fungus gardens and provides insight into the molecular dynamics underlying the symbiosis between these dominant herbivores and their obligate fungal cultivar.

  2. Interactions between Fusarium verticillioides, Ustilago maydis, and Zea mays: an endophyte, a pathogen, and their shared plant host.

    Science.gov (United States)

    Rodriguez Estrada, Alma E; Jonkers, Wilfried; Kistler, H Corby; May, Georgiana

    2012-07-01

    Highly diverse communities of microbial symbionts occupy eukaryotic organisms, including plants. While many well-studied symbionts may be characterized as either parasites or as mutualists, the prevalent but cryptic endophytic fungi are less easily qualified because they do not cause observable symptoms of their presence within their host. Here, we investigate the interactions of an endophytic fungus, Fusarium verticillioides with a pathogen, Ustilago maydis, as they occur within maize (Zea mays). We used experimental inoculations to evaluate metabolic mechanisms by which these three organisms might interact. We assessed the impacts of fungal-fungal interactions on endophyte and pathogen growth within the plant, and on plant growth. We find that F. verticillioides modulates the growth of U. maydis and thus decreases the pathogen's aggressiveness toward the plant. With co-inoculation of the endophyte with the pathogen, plant growth is similar to that which would be gained without the pathogen present. However, the endophyte may also break down plant compounds that limit U. maydis growth, and obtains a growth benefit from the presence of the pathogen. Thus, an endophyte such as F. verticillioides may function as both a defensive mutualist and a parasite, and express nutritional modes that depend on ecological context. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Bacterial pathogen phytosensing in transgenic tobacco and Arabidopsis plants.

    Science.gov (United States)

    Liu, Wusheng; Mazarei, Mitra; Rudis, Mary R; Fethe, Michael H; Peng, Yanhui; Millwood, Reginald J; Schoene, Gisele; Burris, Jason N; Stewart, C Neal

    2013-01-01

    Plants are subject to attack by a wide range of phytopathogens. Current pathogen detection methods and technologies are largely constrained to those occurring post-symptomatically. Recent efforts were made to generate plant sentinels (phytosensors) that can be used for sensing and reporting pathogen contamination in crops. Engineered phytosensors indicating the presence of plant pathogens as early-warning sentinels potentially have tremendous utility as wide-area detectors. We previously showed that synthetic promoters containing pathogen and/or defence signalling inducible cis-acting regulatory elements (RE) fused to a fluorescent protein (FP) reporter could detect phytopathogenic bacteria in a transient phytosensing system. Here, we further advanced this phytosensing system by developing stable transgenic tobacco and Arabidopsis plants containing candidate constructs. The inducibility of each synthetic promoter was examined in response to biotic (bacterial pathogens) or chemical (plant signal molecules salicylic acid, ethylene and methyl jasmonate) treatments using stably transgenic plants. The treated plants were visualized using epifluorescence microscopy and quantified using spectrofluorometry for FP synthesis upon induction. Time-course analyses of FP synthesis showed that both transgenic tobacco and Arabidopsis plants were capable to respond in predictable ways to pathogen and chemical treatments. These results provide insights into the potential applications of transgenic plants as phytosensors and the implementation of emerging technologies for monitoring plant disease outbreaks in agricultural fields.

  4. Photodynamic inactivation of conidia of the fungus Colletotrichum abscissum on Citrus sinensis plants with methylene blue under solar radiation.

    Science.gov (United States)

    Gonzales, Júlia C; Brancini, Guilherme T P; Rodrigues, Gabriela B; Silva-Junior, Geraldo José; Bachmann, Luciano; Wainwright, Mark; Braga, Gilberto Ú L

    2017-09-14

    Antimicrobial photodynamic treatment (APDT) is a promising light based approach to control diseases caused by plant-pathogenic fungi. In the present study, we evaluated the effects of APDT with the phenothiazinium photosensitizer methylene blue (MB) under solar radiation on the germination and viability of conidia of the pathogenic fungus Colletotricum abscissum (former Colletotrichum acutatum sensu lato). Experiments were performed both on petals and leaves of sweet orange (Citrus sinensis) in different seasons and weather conditions. Conidial suspensions were deposited on the leaves and petals surface, treated with the PS (25 or 50μM) and exposed to solar radiation for only 30min. The effects of APDT on conidia were evaluated by counting the colony forming units recovered from leaves and petals and by direct evaluating conidial germination on the surface of these plant organs after the treatment. To better understand the mechanistic of conidial photodynamic inactivation, the effect of APDT on the permeability of the conidial plasma membrane was assessed using the fluorescent probe propidium iodide (PI) together with flow cytometry and fluorescence microscopy. APDT with MB and solar exposure killed C. abscissum conidia and prevented their germination on both leaves and petals of citrus. Reduction of conidial viability was up to three orders of magnitude and a complete photodynamic inactivation was achieved in some of the treatments. APDT damaged the conidial plasma membrane and increased its permeability to PI. No damage to sweet orange flowers or leaves was observed after APDT. The demonstration of the efficacy of APDT on the plant host represents a further step towards the use of the method for control phytopathogens in the field. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Epigenetic regulation of development and pathogenesis in fungal plant pathogens.

    Science.gov (United States)

    Dubey, Akanksha; Jeon, Junhyun

    2017-08-01

    Evidently, epigenetics is at forefront in explaining the mechanisms underlying the success of human pathogens and in the identification of pathogen-induced modifications within host plants. However, there is a lack of studies highlighting the role of epigenetics in the modulation of the growth and pathogenicity of fungal plant pathogens. In this review, we attempt to highlight and discuss the role of epigenetics in the regulation of the growth and pathogenicity of fungal phytopathogens using Magnaporthe oryzae, a devastating fungal plant pathogen, as a model system. With the perspective of wide application in the understanding of the development, pathogenesis and control of other fungal pathogens, we attempt to provide a synthesized view of the epigenetic studies conducted on M. oryzae to date. First, we discuss the mechanisms of epigenetic modifications in M. oryzae and their impact on fungal development and pathogenicity. Second, we highlight the unexplored epigenetic mechanisms and areas of research that should be considered in the near future to construct a holistic view of epigenetic functioning in M. oryzae and other fungal plant pathogens. Importantly, the development of a complete understanding of the modulation of epigenetic regulation in fungal pathogens can help in the identification of target points to combat fungal pathogenesis. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  6. Transcriptional reprogramming underpins enhanced plant growth promotion by the biocontrol fungus Trichoderma hamatum GD12 during antagonistic interactions with Sclerotinia sclerotiorum in soil.

    Science.gov (United States)

    Shaw, Sophie; Le Cocq, Kate; Paszkiewicz, Konrad; Moore, Karen; Winsbury, Rebecca; de Torres Zabala, Marta; Studholme, David J; Salmon, Deborah; Thornton, Christopher R; Grant, Murray R

    2016-12-01

    The free-living soil fungus Trichoderma hamatum strain GD12 is notable amongst Trichoderma strains in both controlling plant diseases and stimulating plant growth, a property enhanced during its antagonistic interactions with pathogens in soil. These attributes, alongside its markedly expanded genome and proteome compared with other biocontrol and plant growth-promoting Trichoderma strains, imply a rich potential for sustainable alternatives to synthetic pesticides and fertilizers for the control of plant disease and for increasing yields. The purpose of this study was to investigate the transcriptional responses of GD12 underpinning its biocontrol and plant growth promotion capabilities during antagonistic interactions with the pathogen Sclerotinia sclerotiorum in soil. Using an extensive mRNA-seq study capturing different time points during the pathogen-antagonist interaction in soil, we show that dynamic and biphasic signatures in the GD12 transcriptome underpin its biocontrol and plant (lettuce) growth-promoting activities. Functional predictions of differentially expressed genes demonstrate the enrichment of transcripts encoding proteins involved in transportation and oxidation-reduction reactions during both processes and an over-representation of siderophores. We identify a biphasic response during biocontrol characterized by a significant induction of transcripts encoding small-secreted cysteine-rich proteins, secondary metabolite-producing gene clusters and genes unique to GD12. These data support the hypothesis that Sclerotinia biocontrol is mediated by the synthesis and secretion of antifungal compounds and that GD12's unique reservoir of uncharacterized genes is actively recruited during the effective biological control of a plurivorous plant pathogen. © 2016 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.

  7. The components of rice and watermelon root exudates and their effects on pathogenic fungus and watermelon defense.

    Science.gov (United States)

    Ren, Lixuan; Huo, Hongwei; Zhang, Fang; Hao, Wenya; Xiao, Liang; Dong, Caixia; Xu, Guohua

    2016-06-02

    Watermelon (Citrullus lanatus) is susceptible to wilt disease caused by the fungus Fusarium oxysporum f. sp niveum (FON). Intercropping management of watermelon/aerobic rice (Oryza sativa) alleviates watermelon wilt disease, because some unidentified component(s) in rice root exudates suppress FON sporulation and spore germination. Here, we show that the phenolic acid p-coumaric acid is present in rice root exudates only, and it inhibits FON spore germination and sporulation. We found that exogenously applied p-coumaric acid up-regulated the expression of ClPR3 in roots, as well as increased chitinase activity in leaves. Furthermore, exogenously applied p-coumaric acid increased β-1,3-glucanase activity in watermelon roots. By contrast, we found that ferulic acid was secreted by watermelon roots, but not by rice roots, and that it stimulated spore germination and sporulation of FON. Exogenous application of ferulic acid down-regulated ClPR3 expression and inhibited chitinase activity in watermelon leaves. Salicylic acid was detected in both watermelon and rice root exudates, which stimulated FON spore germination at low concentrations and suppressed spore germination at high concentrations. Exogenously applied salicylic acid did not alter ClPR3 expression, but did increase chitinase and β-1,3-glucanase activities in watermelon leaves. Together, our results show that the root exudates of phenolic acids were different between rice and watermelon, which lead to their special ecological roles on pathogenic fungus and watermelon defense.

  8. Isolation and detection of taxol, an anticancer drug produced from Lasiodiplodia theobromae, an endophytic fungus of the medicinal plant Morinda citrifolia

    National Research Council Canada - National Science Library

    Mohan Pandi; Rangarajulu Senthil Kumaran; Yong-Keun Choi; Hyung Joo Kim; Johnpaul Muthumary

    2011-01-01

      To determine the production of taxol from an endophytic fungus, Lasiodiplodia theobromae isolated from the medicinal plant Morinda citrifolia and also, to evaluate its cytotoxicity against human...

  9. A small cysteine-rich protein from the Asian soybean rust fungus, Phakopsora pachyrhizi, suppresses plant immunity

    Science.gov (United States)

    The Asian soybean rust fungus, Phakopsora pachyrhizi, is an obligate pathogen capable of causing explosive disease epidemics that drastically reduce the yield of soybean (Glycine max). Currently, the molecular mechanisms by which P. pachyrhizi and other rust fungi cause disease are poorly understood...

  10. In vitro antifungal activity of three geophytic plant extracts against three post-harvest pathogenic fungi.

    Science.gov (United States)

    Maswada, Hanafey F; Abdallah, Sabry A

    2013-12-01

    Plant extracts appear to be one of the most effective alternative methods of plant diseases control which are less harmful to human beings and environment. In vitro antifungal activity of methanolic extracts of three promising wild geophytic plants against three post-harvest pathogenic fungi using radial growth technique was conducted. These extracts included the shoot system (S) and underground parts (R) of Asparagus stipularis, Cyperus capitatus and Stipagrostis lanata. The tested fungi were Alternaria solani, Aspergillus niger and Rhizopus stolonifer. The results exhibited that, all plant extracts had antifungal activity against the tested fungi. The antifungal activity greatly varied depending on plant parts and/or plant species. R. stolonifer was the most susceptible fungus to the tested plant extracts followed by A. niger and then A. solani. On the other hand, the most effective plant extracts against tested fungi were S. lanata (S) and A. stipularis (R). The most effective plant extracts against R. stolonifer were S. lanata (R) and C. capitatus (S). While, the extracts of A. stipularis (R) and S. lanata (S) were the most effective against A. niger. The extracts of C. capitatus (S) and S. lanata (S) exhibited the highest antifungal activity against A. solani. The results demonstrated that, the methanolic extracts of A. stipularis, C. capitatus and S. lanata had potential antifungal activity against A. solani, A. niger and R. stolonifer.

  11. Two independent S-phase checkpoints regulate appressorium-mediated plant infection by the rice blast fungus Magnaporthe oryzae

    Science.gov (United States)

    Osés-Ruiz, Míriam; Sakulkoo, Wasin; Littlejohn, George R.; Martin-Urdiroz, Magdalena

    2017-01-01

    To cause rice blast disease, the fungal pathogen Magnaporthe oryzae develops a specialized infection structure called an appressorium. This dome-shaped, melanin-pigmented cell generates enormous turgor and applies physical force to rupture the rice leaf cuticle using a rigid penetration peg. Appressorium-mediated infection requires septin-dependent reorientation of the F-actin cytoskeleton at the base of the infection cell, which organizes polarity determinants necessary for plant cell invasion. Here, we show that plant infection by M. oryzae requires two independent S-phase cell-cycle checkpoints. Initial formation of appressoria on the rice leaf surface requires an S-phase checkpoint that acts through the DNA damage response (DDR) pathway, involving the Cds1 kinase. By contrast, appressorium repolarization involves a novel, DDR-independent S-phase checkpoint, triggered by appressorium turgor generation and melanization. This second checkpoint specifically regulates septin-dependent, NADPH oxidase-regulated F-actin dynamics to organize the appressorium pore and facilitate entry of the fungus into host tissue. PMID:28028232

  12. Secretome of fungus-infected aphids documents high pathogen activity and weak host response

    DEFF Research Database (Denmark)

    Grell, Morten Nedergaard; Jensen, Annette Bruun; Olsen, Peter B.

    2011-01-01

    Discovery of novel secretome proteins contributes to the understanding of host-pathogen interactions. Here we report a rich diversity of secreted proteins from the interaction between grain aphids (host, insect order Hemiptera) and fungi of the order Entomophthorales (insect pathogens), made poss...

  13. Prevalence of the pathogenic chytrid fungus, Batrachochytrium dendrobatidis, in an endangered population of northern leopard frogs, Rana pipiens

    Directory of Open Access Journals (Sweden)

    Govindarajulu Purnima

    2010-03-01

    Full Text Available Abstract Background Emerging infectious diseases threaten naïve host populations with extinction. Chytridiomycosis, an emerging infectious disease of amphibians, is caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd and has been linked to global declines in amphibians. Results We monitored the prevalence of Bd for four years in the Northern leopard frog, Rana pipiens, which is critically imperiled in British Columbia (BC, Canada. The prevalence of Bd initially increased and then remained constant over the last three years of the study. Young of the year emerging from breeding ponds in summer were rarely infected with Bd. Some individuals cleared their Bd infections and the return rate between infected and uninfected individuals was not significantly different. Conclusions The BC population of R. pipiens appears to have evolved a level of resistance that allows it to co-exist with Bd. However, this small population of R. pipiens remains vulnerable to extinction.

  14. Sensitivity of the Entomogenous Fungus Beauveria bassiana to Selected Plant Growth Regulators and Spray Additives

    Science.gov (United States)

    Storey, Greggory K.; Gardner, Wayne A.

    1986-01-01

    Mefluidide was the only one of four plant growth regulators that caused little to no significant inhibition of in vitro germination and growth of the entomogenous fungus Beauveria bassiana. Silaid, paclobutrazol, and flurprimidol significantly inhibited germination and growth. Mortality of fall armyworm, Spodoptera frugiperda, resulting from B. bassiana was significantly reduced when larvae were exposed to conidia plus soil treated with paclobutrazol. Larval mortality resulting from conidia plus soil treated with mefluidide did not differ significantly from mortality resulting from untreated conidia. Triton CS-7 was the only one of eight spray adjuvants that significantly inhibited germination of B. bassiana conidia. PMID:16347095

  15. Gymnemagenin-producing endophytic fungus isolated from a medicinal plant Gymnema sylvestre R.Br.

    Science.gov (United States)

    Parthasarathy, Ramalingam; Sathiyabama, Muthukrishnan

    2014-03-01

    Gymnema sylvestre is a plant containing the triterpenoid gymnemagenin, which is used in the pharmaceutical industry as an antidiabetic agent. The objective of this study was to determine whether endophytic fungi, isolated from G. sylvestre, produce gymnemagenin. We isolated an endophytic fungal strain from the leaves of G. sylvestre which produces gymnemagenin in the medium. The fungus was identified as Penicillium oxalicum based on morphological and molecular methods. The strain had a component with the same TLC Rf value and HPLC retention time as authentic gymnemagenin. The presence of gymnemagenin was further confirmed by FTIR, UV, and (1)H NMR analyses.

  16. Pestalofones A-E, bioactive cyclohexanone derivatives from the plant endophytic fungus Pestalotiopsis fici.

    Science.gov (United States)

    Liu, Ling; Liu, Shuchun; Chen, Xulin; Guo, Liangdong; Che, Yongsheng

    2009-01-15

    Pestalofones A-E (1-5), five new cyclohexanone derivatives, have been isolated from cultures of the plant endophytic fungus Pestalotiopsis fici, along with the known compounds, isosulochrin (6), isosulochrin dehydrate (7), and iso-A82775C (8). The structures of 1-5 were determined by NMR spectroscopy, and the absolute configuration of 1 was assigned using the modified Mosher method. Compounds 1, 2, and 5 displayed inhibitory effects on HIV-1 replication in C8166 cells, whereas 3 and 5 showed significant antifungal activity against Aspergillus fumigatus.

  17. A Fatty Acid Glycoside from a Marine-Derived Fungus Isolated from Mangrove Plant Scyphiphora hydrophyllacea

    Directory of Open Access Journals (Sweden)

    Wen-Li Mei

    2012-03-01

    Full Text Available To study the antimicrobial components from the endophytic fungus A1 of mangrove plant Scyphiphora hydrophyllacea Gaertn. F., a new fatty acid glucoside was isolated by column chromatography from the broth of A1, and its structure was identified as R-3-hydroxyundecanoic acid methylester-3-O-α-l-rhamnopyranoside (1 by spectroscopic methods including 1D and 2D NMR (HMQC, 1H-1H COSY and HMBC and chemical methods. Antimicrobial assay showed compound 1 possessed modest inhibitory effect on Saphylococcus aureus and methicillin-resistant S. aureus (MRSA using the filter paper disc agar diffusion method.

  18. Host-Induced Gene Silencing of Rice Blast Fungus Magnaporthe oryzae Pathogenicity Genes Mediated by the Brome Mosaic Virus.

    Science.gov (United States)

    Zhu, Lin; Zhu, Jian; Liu, Zhixue; Wang, Zhengyi; Zhou, Cheng; Wang, Hong

    2017-09-26

    Magnaportheoryzae is a devastating plant pathogen, which has a detrimental impact on rice production worldwide. Despite its agronomical importance, some newly-emerging pathotypes often overcome race-specific disease resistance rapidly. It is thus desirable to develop a novel strategy for the long-lasting resistance of rice plants to ever-changing fungal pathogens. Brome mosaic virus (BMV)-induced RNA interference (RNAi) has emerged as a useful tool to study host-resistance genes for rice blast protection. Planta-generated silencing of targeted genes inside biotrophic pathogens can be achieved by expression of M.oryzae-derived gene fragments in the BMV-mediated gene silencing system, a technique termed host-induced gene silencing (HIGS). In this study, the effectiveness of BMV-mediated HIGS in M.oryzae was examined by targeting three predicted pathogenicity genes, MoABC1,MoMAC1 and MoPMK1. Systemic generation of fungal gene-specific small interfering RNA (siRNA) molecules induced by inoculation of BMV viral vectors inhibited disease development and reduced the transcription of targeted fungal genes after subsequent M.oryzae inoculation. Combined introduction of fungal gene sequences in sense and antisense orientation mediated by the BMV silencing vectors significantly enhanced the efficiency of this host-generated trans-specific RNAi, implying that these fungal genes played crucial roles in pathogenicity. Collectively, our results indicated that BMV-HIGS system was a great strategy for protecting host plants against the invasion of pathogenic fungi.

  19. [Antimicrobial activities of ant Ponericin W1 against plant pathogens in vitro and the disease resistance in its transgenic Arabidopsis].

    Science.gov (United States)

    Chen, Yong-Fang; Sun, Peng-Wei; Tang, Ding-Zhong

    2013-08-01

    The antimicrobial peptides (AMPs) exhibit a broad antimicrobial spectrum. The application of AMPs from non-plant organisms attracts considerable attention in plant disease resistance engineering. Ponericin W1, isolated from the venom of ant (Pachycondyla goeldii), shows antimicrobial activities against Gram-positive bacteria, Gram-negative bacteria and the budding yeast (Saccharomyces cerevisiae); however, it is not clear whether Ponericin W1 is effective against plant pathogens. The results of this study indicated synthesized Ponericin W1 inhibited mycelial growth of Magnaporthe oryzae and Botrytis cinerea, as well as hyphal growth and spore production of Fusarium graminearum. Besides, Ponericin W1 exhibited antibacterial activities against Pseudomonas syringae pv. tomato and Xanthomonas oryzae pv. oryzae. After codon optimization, Ponericin W1 gene was constructed into plant expression vector, and transformed into Arabidopsis thaliana by floral dip method. The Ponericin W1 was located in intercellular space of the transgenic plants as expected. Compared with the wild-type plants, there were ungerminated spores and less hyphal, conidia on the leaves of transgenic plants after innoculation with the powdery mildew fungus Golovinomyces cichoracearum. After innoculation with the pathogenic bac-terium Pseudomonas syringae pv. tomato, the baceria in the leaves of transgenic plants was significantly less than the wild-type plants, indicating that the transgenic plants displayed enhanced disease resistance to pathogens. These results demonstrate a potential use of Ponericin W1 in genetic engineering for broad-spectrum plant disease resistance.

  20. Chromatin versus pathogens: the function of epigenetics in plant immunity

    Directory of Open Access Journals (Sweden)

    Bo eDing

    2015-09-01

    Full Text Available To defend against pathogens, plants have developed a sophisticated innate immunity that includes effector recognition, signal transduction, and rapid defense responses. Recent evidence has demonstrated that plants utilize the epigenetic control of gene expression to fine-tune their defense when challenged by pathogens. In this review, we highlight the current understanding of the molecular mechanisms of histone modifications (i.e., methylation, acetylation, and ubiquitination and chromatin remodeling that contribute to plant immunity against pathogens. Functions of key histone-modifying and chromatin remodeling enzymes are discussed.

  1. Catalase overexpression reduces the germination time and increases the pathogenicity of the fungus Metarhizium anisopliae.

    Science.gov (United States)

    Morales Hernandez, Claudia Erika; Padilla Guerrero, Israel Enrique; Gonzalez Hernandez, Gloria Angelica; Salazar Solis, Eduardo; Torres Guzman, Juan Carlos

    2010-07-01

    Catalases and peroxidases are the most important enzymes that degrade hydrogen peroxide into water and oxygen. These enzymes and superoxide dismutase are the first lines of cell defense against reactive oxygen species. Metarhizium anisopliae displays an increase in catalase-peroxidase activity during germination and growth. To determine the importance of catalase during the invasion process of M. anisopliae, we isolated the cat1 gene. cat1 cDNA expression in Escherichia coli and the subsequent purification of the protein confirmed that the cat1 gene codes for a monofunctional catalase. Expression analysis of this gene by RT-PCR from RNA isolated from fungus grown in liquid cultures showed a decrease in the expression level of the cat1 gene during germination and an increase during mycelium growth. The expression of this gene in the fungus during the infection process of the larvae of Plutella xylostella also showed a significant increase during invasive growth. Transgenic strains overexpressing the cat1 gene had twice the catalase activity of the wild-type strain. This increase in catalase activity was accompanied by a higher level of resistance to exogenous hydrogen peroxide and a reduction in the germination time. This improvement was also observed during the infection of P. xylostella larvae. M. anisopliae transgenic strains overexpressing the cat1 gene grew and spread faster in the soft tissue of the insect, reducing the time to death of the insect by 25% and the dose required to kill 50% of the population 14-fold.

  2. Plant volatiles cause direct, induced and associational resistance in common bean to the fungal pathogen Colletotrichum lindemuthianum

    National Research Council Canada - National Science Library

    Quintana‐Rodriguez, Elizabeth; Morales‐Vargas, Adan T; Molina‐Torres, Jorge; Ádame‐Alvarez, Rosa M; Acosta‐Gallegos, Jorge A; Heil, Martin; Flynn, Dan

    2015-01-01

    ... ( Phaseolus vulgaris ) cultivar enhance the resistance to the fungus Colletotrichum lindemuthianum in a susceptible cultivar and analysed whether specific VOC s are likely to directly affect the pathogen...

  3. Regulation of primary plant metabolism during plant-pathogen interactions and its contribution to plant defense

    Directory of Open Access Journals (Sweden)

    Clemencia M Rojas

    2014-02-01

    Full Text Available Plants are constantly exposed to microorganisms in the environment and, as a result, have evolved intricate mechanisms to recognize and defend themselves against potential pathogens. One of these responses is the downregulation of photosynthesis and other processes associated with primary metabolism that are essential for plant growth. It has been suggested that the energy saved by downregulation of primary metabolism is diverted and used for defense responses. However, several studies have shown that upregulation of primary metabolism also occurs during plant-pathogen interactions. We propose that upregulation of primary metabolism modulates signal transduction cascades that lead to plant defense responses. In support of this thought, we here compile evidence from the literature to show that upon exposure to pathogens or elicitors, plants induce several genes associated with primary metabolic pathways, such as those involved in the synthesis or degradation of carbohydrates, amino acids and lipids. In addition, genetic studies have confirmed the involvement of these metabolic pathways in plant defense responses. This review provides a new perspective highlighting the relevance of primary metabolism in regulating plant defense against pathogens with the hope to stimulate further research in this area.

  4. Sex and parasites: genomic and transcriptomic analysis of Microbotryum lychnidis-dioicae, the biotrophic and plant-castrating anther smut fungus.

    Science.gov (United States)

    Perlin, Michael H; Amselem, Joelle; Fontanillas, Eric; Toh, Su San; Chen, Zehua; Goldberg, Jonathan; Duplessis, Sebastien; Henrissat, Bernard; Young, Sarah; Zeng, Qiandong; Aguileta, Gabriela; Petit, Elsa; Badouin, Helene; Andrews, Jared; Razeeq, Dominique; Gabaldón, Toni; Quesneville, Hadi; Giraud, Tatiana; Hood, Michael E; Schultz, David J; Cuomo, Christina A

    2015-06-16

    The genus Microbotryum includes plant pathogenic fungi afflicting a wide variety of hosts with anther smut disease. Microbotryum lychnidis-dioicae infects Silene latifolia and replaces host pollen with fungal spores, exhibiting biotrophy and necrosis associated with altering plant development. We determined the haploid genome sequence for M. lychnidis-dioicae and analyzed whole transcriptome data from plant infections and other stages of the fungal lifecycle, revealing the inventory and expression level of genes that facilitate pathogenic growth. Compared to related fungi, an expanded number of major facilitator superfamily transporters and secretory lipases were detected; lipase gene expression was found to be altered by exposure to lipid compounds, which signaled a switch to dikaryotic, pathogenic growth. In addition, while enzymes to digest cellulose, xylan, xyloglucan, and highly substituted forms of pectin were absent, along with depletion of peroxidases and superoxide dismutases that protect the fungus from oxidative stress, the repertoire of glycosyltransferases and of enzymes that could manipulate host development has expanded. A total of 14% of the genome was categorized as repetitive sequences. Transposable elements have accumulated in mating-type chromosomal regions and were also associated across the genome with gene clusters of small secreted proteins, which may mediate host interactions. The unique absence of enzyme classes for plant cell wall degradation and maintenance of enzymes that break down components of pollen tubes and flowers provides a striking example of biotrophic host adaptation.

  5. The cuticle and plant defense to pathogens

    Directory of Open Access Journals (Sweden)

    Jean-Pierre eMetraux

    2014-06-01

    Full Text Available The cuticle provides a physical barrier against water loss and protects against irradiation, xenobiotics and pathogens. Components of the cuticle are perceived by invading fungi and activate developmental processes during pathogenesis. In addition, cuticle alterations of various types induce a syndrome of reactions that often results in resistance to necrotrophs. This article reviews the current knowledge on the role of the cuticle in relation to the perception of pathogens and activation of defenses.

  6. Recent developments in pathogen detection arrays: implications for fungal plant pathogens and use in practica

    NARCIS (Netherlands)

    Lievens, B.; Thomma, B.P.H.J.

    2005-01-01

    The failure to adequately identify plant pathogens from culture-based morphological techniques has led to the development of culture-independent molecular approaches. Increasingly, diagnostic laboratories are pursuing fast routine methods that provide reliable identification, sensitive detection, an

  7. Carbohydrate-related enzymes of important Phytophthora plant pathogens

    NARCIS (Netherlands)

    Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P; van den Brink, J.

    2014-01-01

    Carbohydrate-Active enZymes (CAZymes) form particularly interesting targets to study in plant pathogens. Despite the fact that many CAZymes are pathogenicity factors, oomycete CAZymes have received significantly less attention than effectors in the literature. Here we present an analysis of the CAZy

  8. Diaporthe: a genus of endophytic, saprobic and plant pathogenic fungi

    NARCIS (Netherlands)

    Gomes, R.R.; Glienke, C.; Videira, S.I.R.; Lombard, L.; Groenewald, J.Z.; Crous, P.W.

    2013-01-01

    Diaporthe (Phomopsis) species have often been reported as plant pathogens, non-pathogenic endophytes or saprobes, commonly isolated from a wide range of hosts. The primary aim of the present study was to resolve the taxonomy and phylogeny of a large collection of Diaporthe species occurring on diver

  9. Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens

    Science.gov (United States)

    Justin B. Runyon; Mark C. Mescher; Consuelo M. De Moraes

    2010-01-01

    Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling and response to herbivores and pathogens has expanded rapidly in recent years...

  10. Arsenal of plant cell wall degrading enzymes reflects host preference among plant pathogenic fungi

    Science.gov (United States)

    Discovery and development of novel plant cell wall degrading enzymes is a key step towards more efficient depolymerization of polysaccharides to fermentable sugars for production of liquid transportation biofuels and other bioproducts. The industrial fungus Trichoderma reesei is known to be highly c...

  11. Chromatin versus pathogens: the function of epigenetics in plant immunity

    OpenAIRE

    Ding, Bo; Wang, Guo-Liang

    2015-01-01

    To defend against pathogens, plants have developed a sophisticated innate immunity that includes effector recognition, signal transduction, and rapid defense responses. Recent evidence has demonstrated that plants utilize the epigenetic control of gene expression to fine-tune their defense when challenged by pathogens. In this review, we highlight the current understanding of the molecular mechanisms of histone modifications (i.e., methylation, acetylation, and ubiquitination) and chromatin r...

  12. Engineered resistance against fungal plant pathogens

    NARCIS (Netherlands)

    Honée, G.

    1999-01-01

    Development of genetic engineering technology and molecular characterization of plant defense responses have provided strategies for controlling plant diseases additional to those based on chemical control or classical breeding programs. Most of these alternative strategies are based on the overprod

  13. Detection and Diagnostics of Plant Pathogens

    NARCIS (Netherlands)

    Gullino, M.L.; Bonants, P.J.M.

    2014-01-01

    This book is part of the Plant Pathology in the 21st Century Series, started in the occasion of the IX International Congress of Plant Pathology, Torino, 2008. In conjunction with the Xth International Congress of Plant Pathology, held in Beijing in August 2013. Although deriving from a Congress, th

  14. Caterpillars and fungal pathogens: two co-occurring parasites of an ant-plant mutualism.

    Directory of Open Access Journals (Sweden)

    Olivier Roux

    Full Text Available In mutualisms, each interacting species obtains resources from its partner that it would obtain less efficiently if alone, and so derives a net fitness benefit. In exchange for shelter (domatia and food, mutualistic plant-ants protect their host myrmecophytes from herbivores, encroaching vines and fungal pathogens. Although selective filters enable myrmecophytes to host those ant species most favorable to their fitness, some insects can by-pass these filters, exploiting the rewards supplied whilst providing nothing in return. This is the case in French Guiana for Cecropia obtusa (Cecropiaceae as Pseudocabima guianalis caterpillars (Lepidoptera, Pyralidae can colonize saplings before the installation of their mutualistic Azteca ants. The caterpillars shelter in the domatia and feed on food bodies (FBs whose production increases as a result. They delay colonization by ants by weaving a silk shield above the youngest trichilium, where the FBs are produced, blocking access to them. This probable temporal priority effect also allows female moths to lay new eggs on trees that already shelter caterpillars, and so to occupy the niche longer and exploit Cecropia resources before colonization by ants. However, once incipient ant colonies are able to develop, they prevent further colonization by the caterpillars. Although no higher herbivory rates were noted, these caterpillars are ineffective in protecting their host trees from a pathogenic fungus, Fusarium moniliforme (Deuteromycetes, that develops on the trichilium in the absence of mutualistic ants. Therefore, the Cecropia treelets can be parasitized by two often overlooked species: the caterpillars that shelter in the domatia and feed on FBs, delaying colonization by mutualistic ants, and the fungal pathogen that develops on old trichilia. The cost of greater FB production plus the presence of the pathogenic fungus likely affect tree growth.

  15. [Plants and pathogenic agents, a refined and dangerous relationship: the example of fungi].

    Science.gov (United States)

    Esquerré-Tugayé, M T

    2001-10-01

    Plant-fungus interactions are highly diverse, either being beneficial to the host plant such as those leading to mycorhizal symbiosis, or very detrimental when leading to severe diseases. Since the beginning of agriculture, improvement of plant resistance to pathogens has remained a major challenge. Breeding for resistance, first conducted empirically in the past centuries, was then performed on a more theoretical basis after the statement of heredity laws by Mendel at the end of the XIXth century. As a result, most cultivated species contain various cultivars whose resistance or susceptibility to a given pathogen species depend on their interaction with various races of that pathogen. Such highly specific race-cultivar systems are particularly suited for understanding the molecular dialogue which underlies compatible (host susceptible/pathogen virulent) or incompatible (host resistant/pathogen avirulent) interactions. During the twentieth century, one of the major events that paved the way for future research was the statement by Flor [1946, 1947] of the gene-for-gene concept. Studying inheritance of the disease phenotype in the interaction between flax and Melampsora lini he showed that resistance in the host and avirulence in the pathogen are dictated by single dominant genes which correspond one to one, i.e. one resistance gene for one avirulence gene. The fact that incompatibility may depend on the presence of only one resistance (R) gene in the host and one avirulence (Avr) gene in the pathogen was fully confirmed about 40 years later. Molecular genetics and complementation experiments have allowed to isolate numerous R and Avr genes from various plant-pathogen systems, and to verify the gene-for-gene concept. These studies have enlightened the elicitor/receptor concept, formerly introduced to account for the specificity of the compatible and incompatible interactions. The present knowledge of R and Avr genes also allows to predict how such genes have evolved

  16. Populations of a susceptible amphibian species can grow despite the presence of a pathogenic chytrid fungus.

    Directory of Open Access Journals (Sweden)

    Ursina Tobler

    Full Text Available Disease can be an important driver of host population dynamics and epizootics can cause severe host population declines. Batrachochytrium dendrobatidis (Bd, the pathogen causing amphibian chytridiomycosis, may occur epizootically or enzootically and can harm amphibian populations in many ways. While effects of Bd epizootics are well documented, the effects of enzootic Bd have rarely been described. We used a state-space model that accounts for observation error to test whether population trends of a species highly susceptible to Bd, the midwife toad Alytes obstetricans, are negatively affected by the enzootic presence of the pathogen. Unexpectedly, Bd had no negative effect on population growth rates from 2002-2008. This suggests that negative effects of disease on individuals do not necessarily translate into negative effects at the population level. Populations of amphibian species that are susceptible to the emerging disease chytridiomycosis can persist despite the enzootic presence of the pathogen under current environmental conditions.

  17. Gene expression in mycorrhizal orchid protocorms suggests a friendly plant-fungus relationship.

    Science.gov (United States)

    Perotto, Silvia; Rodda, Marco; Benetti, Alex; Sillo, Fabiano; Ercole, Enrico; Rodda, Michele; Girlanda, Mariangela; Murat, Claude; Balestrini, Raffaella

    2014-06-01

    Orchids fully depend on symbiotic interactions with specific soil fungi for seed germination and early development. Germinated seeds give rise to a protocorm, a heterotrophic organ that acquires nutrients, including organic carbon, from the mycorrhizal partner. It has long been debated if this interaction is mutualistic or antagonistic. To investigate the molecular bases of the orchid response to mycorrhizal invasion, we developed a symbiotic in vitro system between Serapias vomeracea, a Mediterranean green meadow orchid, and the rhizoctonia-like fungus Tulasnella calospora. 454 pyrosequencing was used to generate an inventory of plant and fungal genes expressed in mycorrhizal protocorms, and plant genes could be reliably identified with a customized bioinformatic pipeline. A small panel of plant genes was selected and expression was assessed by real-time quantitative PCR in mycorrhizal and non-mycorrhizal protocorm tissues. Among these genes were some markers of mutualistic (e.g. nodulins) as well as antagonistic (e.g. pathogenesis-related and wound/stress-induced) genes. None of the pathogenesis or wound/stress-related genes were significantly up-regulated in mycorrhizal tissues, suggesting that fungal colonization does not trigger strong plant defence responses. In addition, the highest expression fold change in mycorrhizal tissues was found for a nodulin-like gene similar to the plastocyanin domain-containing ENOD55. Another nodulin-like gene significantly more expressed in the symbiotic tissues of mycorrhizal protocorms was similar to a sugar transporter of the SWEET family. Two genes coding for mannose-binding lectins were significantly up-regulated in the presence of the mycorrhizal fungus, but their role in the symbiosis is unclear.

  18. How phytohormones shape interactions between plants and the soil-borne fungus Fusarium oxysporum

    Directory of Open Access Journals (Sweden)

    Xiaotang eDi

    2016-02-01

    Full Text Available Plants interact with a huge variety of soil microbes, ranging from pathogenic to mutualistic. The Fusarium oxysporum (Fo species complex consists of ubiquitous soil inhabiting fungi that can infect and cause disease in over 120 different plant species including tomato, banana, cotton and Arabidopsis. However, in many cases Fo colonization remains symptomless or even has beneficial effects on plant growth and/or stress tolerance. Also in pathogenic interactions a lengthy asymptomatic phase usually precedes disease development. All this indicates a sophisticated and fine-tuned interaction between Fo and its host. The molecular mechanisms underlying this balance are poorly understood. Plant hormone signaling networks emerge as key regulators of plant-microbe interactions in general. In this review we summarize the effects of the major phytohormones on the interaction between Fo and its diverse hosts. Generally, Salicylic Acid (SA signaling reduces plant susceptibility, whereas Jasmonic Acid (JA, Ethylene (ET, Abscisic Acid (ABA and auxin have complex effects, and are potentially hijacked by Fo for host manipulation. Finally, we discuss how plant hormones and Fo effectors balance the interaction from beneficial to pathogenic and vice versa.

  19. Recognition of bacterial plant pathogens: local, systemic and transgenerational immunity.

    Science.gov (United States)

    Henry, Elizabeth; Yadeta, Koste A; Coaker, Gitta

    2013-09-01

    Bacterial pathogens can cause multiple plant diseases and plants rely on their innate immune system to recognize and actively respond to these microbes. The plant innate immune system comprises extracellular pattern recognition receptors that recognize conserved microbial patterns and intracellular nucleotide binding leucine-rich repeat (NLR) proteins that recognize specific bacterial effectors delivered into host cells. Plants lack the adaptive immune branch present in animals, but still afford flexibility to pathogen attack through systemic and transgenerational resistance. Here, we focus on current research in plant immune responses against bacterial pathogens. Recent studies shed light onto the activation and inactivation of pattern recognition receptors and systemic acquired resistance. New research has also uncovered additional layers of complexity surrounding NLR immune receptor activation, cooperation and sub-cellular localizations. Taken together, these recent advances bring us closer to understanding the web of molecular interactions responsible for coordinating defense responses and ultimately resistance.

  20. Role of the rttA gene in morphogenesis, stress response, and virulence in the human pathogenic fungus Penicillium marneffei.

    Science.gov (United States)

    Suwunnakorn, Sumanun; Cooper, Chester R; Kummasook, Aksarakorn; Pongpom, Monsicha; Vanittanakom, Pramote; Vanittanakom, Nongnuch

    2015-02-01

    Penicillium marneffei is a human pathogenic fungus and the only thermally dimorphic species of the genus. At 25°C, P. marneffei grows as a mycelium that produces conidia in chains. However, when incubated at 37°C or following infection of host tissue, the fungus develops as a fission yeast. Previously, a mutant (strain I133) defective in morphogenesis was generated via Agrobacterium-mediated transformation. Specifically, the rtt109 gene (subsequently designated rttA) in this mutant was interrupted by T-DNA insertion. We characterized strain I133 and the possible roles of the mutated rttA gene in altered P. marneffei phenotypes. At 25°C, the rttA mutant produces fewer conidia than the wild type and a complemented mutant strain, as well as slower rates of conidial germination; however, strain I133 continued to grow as a yeast in 37°C-incubated cultures. Furthermore, whereas the wild type exhibited increased expression of rttA at 37°C in response to the DNA-damaging agent methyl methane sulfonate, strain I133 was hypersensitive to this and other genotoxic agents. Under similar conditions, the rttA mutant exhibited decreased expression of genes associated with carbohydrate metabolism and oxidative stress. Importantly, when compared with the wild-type and the complemented strain, I133 was significantly less virulent in a Galleria infection model when the larvae were incubated at 37°C. Moreover, the mutant exhibited inappropriate phase transition in vivo. In conclusion, the rttA gene plays important roles in morphogenesis, carbohydrate metabolism, stress response, and pathogenesis in P. marneffei, suggesting that this gene may be a potential target for the development of antifungal compounds.

  1. Pathogenicity of the entomopathogenic fungus Metarhizium anisopliae var. major on different stages of the sunn pest Eurygaster integriceps.

    Science.gov (United States)

    Sedighi, Neda; Abbasipour, Habib; Askary, Hassan; Gorjan, Aziz Sheikhi; Karimi, Jaber

    2013-01-01

    The sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), is the most important insect pest of wheat and barley. The population management of this pest is of major concern to wheat producers. One of the potential control strategies is to use entomopathogenic fungi. This study evaluates the pathogenicity of the fungus Metarhizium anisopliae var. major (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) on the sunn pest, E. integriceps. Five concentrations of the fungus were utilized, ranging from 1×10(4) to 1×10(8) conidia/mL, accompanied by controls. Fifth instar nymphs and adults (a migratory summer population and a diapausing population) previously exposed to fungi were sown to isolate the fungi, and the growth parameters were analyzed. A direct spray technique was used to expose the isolates to the E. integriceps. The experiment was repeated four times, and mortalities of the insects for all treatments were recorded daily. The results showed that the mortality of infected nymphs was significantly higher than the mortality of control nymphs. Also, the longevity of infected adults was lower than the controls. The results also showed that diapausing adults of the sunn pest were much more susceptible to infection than the summer adults. Estimated LC50 values for the M14 isolate were 1.4 × 10(6), 1.4 ×10 (5) , and 2.3 × 10(3) spores/mL against the aestivation population, the diapausing population, and 5(th) instar nymphs, respectively. Estimated LT50 values using 10(8) spores/mL of the Mm isolate on the aestivation and diapausing populations were 11.9 and 5.11 days, respectively. The results demonstrated that M. anisoplaie was effective on all of stages of E. integriceps. In addition, the nymphal stage was more susceptible than the adults.

  2. Functional analysis of atfA gene to stress response in pathogenic thermal dimorphic fungus Penicillium marneffei.

    Science.gov (United States)

    Nimmanee, Panjaphorn; Woo, Patrick C Y; Vanittanakom, Pramote; Youngchim, Sirida; Vanittanakom, Nongnuch

    2014-01-01

    Penicillium marneffei, the pathogenic thermal dimorphic fungus is a causative agent of a fatal systemic disease, penicilliosis marneffei, in immunocompromised patients especially HIV patients. For growth and survival, this fungus has to adapt to environmental stresses outside and inside host cells and this adaptation requires stress signaling pathways and regulation of gene expression under various kinds of stresses. In this report, P. marneffei activating transcription factor (atfA) gene encoding bZip-type transcription factor was characterized. To determine functions of this gene, atfA isogenic mutant strain was constructed using the modified split marker recombination method. The phenotypes and susceptibility to varieties of stresses including osmotic, oxidative, heat, UV, cell wall and cell membrane stresses of the mutant strain were compared with the wild type and the atfA complemented strains. Results demonstrated that the mRNA expression level of P. marneffei atfA gene increased under heat stress at 42°C. The atfA mutant was more sensitive to sodium dodecyl sulphate, amphotericin B and tert-butyl hydroperoxide than the wild type and complemented strains but not hydrogen peroxide, menadione, NaCl, sorbitol, calcofluor white, itraconazole, UV stresses and heat stress at 39°C. In addition, recovery of atfA mutant conidia after mouse and human macrophage infections was significantly decreased compared to those of wild type and complemented strains. These results indicated that the atfA gene was required by P. marneffei under specific stress conditions and might be necessary for fighting against host immune cells during the initiation of infection.

  3. Comparative transcriptome analysis of the necrotrophic fungus Ascochyta rabiei during oxidative stress: insight for fungal survival in the host plant.

    Directory of Open Access Journals (Sweden)

    Kunal Singh

    Full Text Available Localized cell death, known as the hypersensitive response (HR, is an important defense mechanism for neutralizing phytopathogens. The hallmark of the HR is an oxidative burst produced by the host plant. We aimed to identify genes of the necrotrophic chickpea blight fungus Ascochyta rabiei that are involved in counteracting oxidative stress. A subtractive cDNA library was constructed after menadione treatment, which resulted in the isolation of 128 unigenes. A reverse northern blot was used to compare transcript profiles after H(2O(2, menadione and sodium nitroprusside treatments. A total of 70 unigenes were found to be upregulated by more than two-fold following menadione treatment at different time intervals. A large number of genes not previously associated with oxidative stress were identified, along with many stress-responsive genes. Differential expression patterns of several genes were validated by quantitative real-time PCR (qRT-PCR and northern blotting. In planta qRT-PCR of several selected genes also showed differential expression patterns during infection and disease progression. These data shed light on the molecular responses of the phytopathogen A. rabiei to overcome oxidative and nitrosative stresses and advance the understanding of necrotrophic fungal pathogen survival mechanisms.

  4. Comparative transcriptome analysis of the necrotrophic fungus Ascochyta rabiei during oxidative stress: insight for fungal survival in the host plant.

    Science.gov (United States)

    Singh, Kunal; Nizam, Shadab; Sinha, Manisha; Verma, Praveen K

    2012-01-01

    Localized cell death, known as the hypersensitive response (HR), is an important defense mechanism for neutralizing phytopathogens. The hallmark of the HR is an oxidative burst produced by the host plant. We aimed to identify genes of the necrotrophic chickpea blight fungus Ascochyta rabiei that are involved in counteracting oxidative stress. A subtractive cDNA library was constructed after menadione treatment, which resulted in the isolation of 128 unigenes. A reverse northern blot was used to compare transcript profiles after H(2)O(2), menadione and sodium nitroprusside treatments. A total of 70 unigenes were found to be upregulated by more than two-fold following menadione treatment at different time intervals. A large number of genes not previously associated with oxidative stress were identified, along with many stress-responsive genes. Differential expression patterns of several genes were validated by quantitative real-time PCR (qRT-PCR) and northern blotting. In planta qRT-PCR of several selected genes also showed differential expression patterns during infection and disease progression. These data shed light on the molecular responses of the phytopathogen A. rabiei to overcome oxidative and nitrosative stresses and advance the understanding of necrotrophic fungal pathogen survival mechanisms.

  5. 14-3-3 proteins in plant-pathogen interactions.

    Science.gov (United States)

    Lozano-Durán, Rosa; Robatzek, Silke

    2015-05-01

    14-3-3 proteins define a eukaryotic-specific protein family with a general role in signal transduction. Primarily, 14-3-3 proteins act as phosphosensors, binding phosphorylated client proteins and modulating their functions. Since phosphorylation regulates a plethora of different physiological responses in plants, 14-3-3 proteins play roles in multiple signaling pathways, including those controlling metabolism, hormone signaling, cell division, and responses to abiotic and biotic stimuli. Increasing evidence supports a prominent role of 14-3-3 proteins in regulating plant immunity against pathogens at various levels. In this review, potential links between 14-3-3 function and the regulation of plant-pathogen interactions are discussed, with a special focus on the regulation of 14-3-3 proteins in response to pathogen perception, interactions between 14-3-3 proteins and defense-related proteins, and 14-3-3 proteins as targets of pathogen effectors.

  6. Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar

    Science.gov (United States)

    Bletz, Molly C.; Rosa, Gonçalo M.; Andreone, Franco; Courtois, Elodie A.; Schmeller, Dirk S.; Rabibisoa, Nirhy H. C.; Rabemananjara, Falitiana C. E.; Raharivololoniaina, Liliane; Vences, Miguel; Weldon, Ché; Edmonds, Devin; Raxworthy, Christopher J.; Harris, Reid N.; Fisher, Matthew C.; Crottini, Angelica

    2015-01-01

    Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique “megadiverse” amphibians. PMID:25719857

  7. Widespread presence of the pathogenic fungus Batrachochytrium dendrobatidis in wild amphibian communities in Madagascar.

    Science.gov (United States)

    Bletz, Molly C; Rosa, Gonçalo M; Andreone, Franco; Courtois, Elodie A; Schmeller, Dirk S; Rabibisoa, Nirhy H C; Rabemananjara, Falitiana C E; Raharivololoniaina, Liliane; Vences, Miguel; Weldon, Ché; Edmonds, Devin; Raxworthy, Christopher J; Harris, Reid N; Fisher, Matthew C; Crottini, Angelica

    2015-02-26

    Amphibian chytridiomycosis, an emerging infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been a significant driver of amphibian declines. While globally widespread, Bd had not yet been reported from within Madagascar. We document surveys conducted across the country between 2005 and 2014, showing Bd's first record in 2010. Subsequently, Bd was detected in multiple areas, with prevalence reaching up to 100%. Detection of Bd appears to be associated with mid to high elevation sites and to have a seasonal pattern, with greater detectability during the dry season. Lineage-based PCR was performed on a subset of samples. While some did not amplify with any lineage probe, when a positive signal was observed, samples were most similar to the Global Panzootic Lineage (BdGPL). These results may suggest that Bd arrived recently, but do not exclude the existence of a previously undetected endemic Bd genotype. Representatives of all native anuran families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique "megadiverse" amphibians.

  8. Monoclonal antibodies against peptidorhamnomannans of Scedosporium apiospermum enhance the pathogenicity of the fungus.

    Directory of Open Access Journals (Sweden)

    Livia C L Lopes

    Full Text Available Scedosporium apiospermum is part of the Pseudallescheria-Scedosporium complex. Peptidorhamnomannans (PRMs are cell wall glycopeptides present in some fungi, and their structures have been characterized in S. apiospermum, S. prolificans and Sporothrix schenckii. Prior work shows that PRMs can interact with host cells and that the glycopeptides are antigenic. In the present study, three monoclonal antibodies (mAbs, IgG1 to S. apiospermum derived PRM were generated and their effects on S. apiospermum were examined in vitro and in vivo. The mAbs recognized a carbohydrate epitope on PRM. In culture, addition of the PRM mAbs increased S. apiospermum conidia germination and reduced conidial phagocytosis by J774.16 macrophages. In a murine infection model, mice treated with antibodies to PRM died prior to control animals. Thus, PRM is involved in morphogenesis and the binding of this glycopeptide by mAbs enhanced the virulence of the fungus. Further insights into the effects of these glycopeptides on the pathobiology of S. apiospermum may lead to new avenues for preventing and treating scedosporiosis.

  9. THE USE OF PLANTS TO PROTECT PLANTS AND FOOD AGAINST FUNGAL PATHOGENS: A REVIEW.

    Science.gov (United States)

    Shuping, D S S; Eloff, J N

    2017-01-01

    Plant fungal pathogens play a crucial role in the profitability, quality and quantity of plant production. These phytopathogens are persistent in avoiding plant defences causing diseases and quality losses around the world that amount to billions of US dollars annually. To control the scourge of plant fungal diseases, farmers have used fungicides to manage the damage of plant pathogenic fungi. Drawbacks such as development of resistance and environmental toxicity associated with these chemicals have motivated researchers and cultivators to investigate other possibilities. Several databases were accessed to determine work done on protecting plants against plant fungal pathogens with plant extracts using search terms "plant fungal pathogen", "plant extracts" and "phytopathogens". Proposals are made on the best extractants and bioassay techniques to be used. In addition to chemical fungicides, biological agents have been used to deal with plant fungal diseases. There are many examples where plant extracts or plant derived compounds have been used as commercial deterrents of fungi on a large scale in agricultural and horticultural setups. One advantage of this approach is that plant extracts usually contain more than one antifungal compound. Consequently the development of resistance of pathogens may be lower if the different compounds affect a different metabolic process. Plants cultivated using plants extracts may also be marketed as organically produced. Many papers have been published on effective antimicrobial compounds present in plant extracts focusing on applications in human health. More research is required to develop suitable, sustainable, effective, cheaper botanical products that can be used to help overcome the scourge of plant fungal diseases. Scientists who have worked only on using plants to control human and animal fungal pathogens should consider the advantages of focusing on plant fungal pathogens. This approach could not only potentially increase

  10. Migrate or evolve: options for plant pathogens under climate change.

    Science.gov (United States)

    Chakraborty, Sukumar

    2013-07-01

    Findings on climate change influence on plant pathogens are often inconsistent and context dependent. Knowledge of pathogens affecting agricultural crops and natural plant communities remains fragmented along disciplinary lines. By broadening the perspective beyond agriculture, this review integrates cross-disciplinary knowledge to show that at scales relevant to climate change, accelerated evolution and changing geographic distribution will be the main implications for pathogens. New races may evolve rapidly under elevated temperature and CO2 , as evolutionary forces act on massive pathogen populations boosted by a combination of increased fecundity and infection cycles under favourable microclimate within enlarged canopy. Changing geographic distribution will bring together diverse lineages/genotypes that do not share common ecological niche, potentially increasing pathogen diversity. However, the uncertainty of model predictions and a lack of synthesis of fragmented knowledge remain as major deficiencies in knowledge. The review contends that the failure to consider scale and human intervention through new technology are major sources of uncertainty. Recognizing that improved biophysical models alone will not reduce uncertainty, it proposes a generic framework to increase focus and outlines ways to integrate biophysical elements and technology change with human intervention scenarios to minimize uncertainty. To synthesize knowledge of pathogen biology and life history, the review borrows the concept of 'fitness' from population biology as a comprehensive measure of pathogen strengths and vulnerabilities, and explores the implications of pathogen mode of nutrition to fitness and its interactions with plants suffering chronic abiotic stress under climate change. Current and future disease management options can then be judged for their ability to impair pathogenic and saprophytic fitness. The review pinpoints improving confidence in model prediction by minimizing

  11. Insights from the genome of the biotrophic fungal plant pathogen Ustilago maydis.

    Science.gov (United States)

    Kämper, Jörg; Kahmann, Regine; Bölker, Michael; Ma, Li-Jun; Brefort, Thomas; Saville, Barry J; Banuett, Flora; Kronstad, James W; Gold, Scott E; Müller, Olaf; Perlin, Michael H; Wösten, Han A B; de Vries, Ronald; Ruiz-Herrera, José; Reynaga-Peña, Cristina G; Snetselaar, Karen; McCann, Michael; Pérez-Martín, José; Feldbrügge, Michael; Basse, Christoph W; Steinberg, Gero; Ibeas, Jose I; Holloman, William; Guzman, Plinio; Farman, Mark; Stajich, Jason E; Sentandreu, Rafael; González-Prieto, Juan M; Kennell, John C; Molina, Lazaro; Schirawski, Jan; Mendoza-Mendoza, Artemio; Greilinger, Doris; Münch, Karin; Rössel, Nicole; Scherer, Mario; Vranes, Miroslav; Ladendorf, Oliver; Vincon, Volker; Fuchs, Uta; Sandrock, Björn; Meng, Shaowu; Ho, Eric C H; Cahill, Matt J; Boyce, Kylie J; Klose, Jana; Klosterman, Steven J; Deelstra, Heine J; Ortiz-Castellanos, Lucila; Li, Weixi; Sanchez-Alonso, Patricia; Schreier, Peter H; Häuser-Hahn, Isolde; Vaupel, Martin; Koopmann, Edda; Friedrich, Gabi; Voss, Hartmut; Schlüter, Thomas; Margolis, Jonathan; Platt, Darren; Swimmer, Candace; Gnirke, Andreas; Chen, Feng; Vysotskaia, Valentina; Mannhaupt, Gertrud; Güldener, Ulrich; Münsterkötter, Martin; Haase, Dirk; Oesterheld, Matthias; Mewes, Hans-Werner; Mauceli, Evan W; DeCaprio, David; Wade, Claire M; Butler, Jonathan; Young, Sarah; Jaffe, David B; Calvo, Sarah; Nusbaum, Chad; Galagan, James; Birren, Bruce W

    2006-11-02

    Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U. maydis belongs to the group of biotrophic parasites (the smuts) that depend on living tissue for proliferation and development. Here we report the genome sequence for a member of this economically important group of biotrophic fungi. The 20.5-million-base U. maydis genome assembly contains 6,902 predicted protein-encoding genes and lacks pathogenicity signatures found in the genomes of aggressive pathogenic fungi, for example a battery of cell-wall-degrading enzymes. However, we detected unexpected genomic features responsible for the pathogenicity of this organism. Specifically, we found 12 clusters of genes encoding small secreted proteins with unknown function. A significant fraction of these genes exists in small gene families. Expression analysis showed that most of the genes contained in these clusters are regulated together and induced in infected tissue. Deletion of individual clusters altered the virulence of U. maydis in five cases, ranging from a complete lack of symptoms to hypervirulence. Despite years of research into the mechanism of pathogenicity in U. maydis, no 'true' virulence factors had been previously identified. Thus, the discovery of the secreted protein gene clusters and the functional demonstration of their decisive role in the infection process illuminate previously unknown mechanisms of pathogenicity operating in biotrophic fungi. Genomic analysis is, similarly, likely to open up new avenues for the discovery of virulence determinants in other pathogens.

  12. Plant systems for recognition of pathogen-associated molecular patterns.

    Science.gov (United States)

    Postel, Sandra; Kemmerling, Birgit

    2009-12-01

    Research of the last decade has revealed that plant immunity consists of different layers of defense that have evolved by the co-evolutional battle of plants with its pathogens. Particular light has been shed on PAMP- (pathogen-associated molecular pattern) triggered immunity (PTI) mediated by pattern recognition receptors. Striking similarities exist between the plant and animal innate immune system that point for a common optimized mechanism that has evolved independently in both kingdoms. Pattern recognition receptors (PRRs) from both kingdoms consist of leucine-rich repeat receptor complexes that allow recognition of invading pathogens at the cell surface. In plants, PRRs like FLS2 and EFR are controlled by a co-receptor SERK3/BAK1, also a leucine-rich repeat receptor that dimerizes with the PRRs to support their function. Pathogens can inject effector proteins into the plant cells to suppress the immune responses initiated after perception of PAMPs by PRRs via inhibition or degradation of the receptors. Plants have acquired the ability to recognize the presence of some of these effector proteins which leads to a quick and hypersensitive response to arrest and terminate pathogen growth.

  13. Molecular battles between plant and pathogenic bacteria in the phyllosphere

    Directory of Open Access Journals (Sweden)

    C.M. Baker

    2010-08-01

    Full Text Available The phyllosphere, i.e., the aerial parts of the plant, provides one of the most important niches for microbial colonization. This niche supports the survival and, often, proliferation of microbes such as fungi and bacteria with diverse lifestyles including epiphytes, saprophytes, and pathogens. Although most microbes may complete the life cycle on the leaf surface, pathogens must enter the leaf and multiply aggressively in the leaf interior. Natural surface openings, such as stomata, are important entry sites for bacteria. Stomata are known for their vital role in water transpiration and gas exchange between the plant and the environment that is essential for plant growth. Recent studies have shown that stomata can also play an active role in limiting bacterial invasion of both human and plant pathogenic bacteria as part of the plant innate immune system. As counter-defense, plant pathogens such as Pseudomonas syringae pv tomato (Pst DC3000 use the virulence factor coronatine to suppress stomate-based defense. A novel and crucial early battleground in host-pathogen interaction in the phyllosphere has been discovered with broad implications in the study of bacterial pathogenesis, host immunity, and molecular ecology of bacterial diseases.

  14. How do filamentous pathogens deliver effector proteins into plant cells?

    Directory of Open Access Journals (Sweden)

    Benjamin Petre

    2014-02-01

    Full Text Available Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens.

  15. How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells?

    Science.gov (United States)

    Petre, Benjamin; Kamoun, Sophien

    2014-01-01

    Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens. PMID:24586116

  16. The use of plants to protect plants and food against fungal pathogens

    African Journals Online (AJOL)

    The use of plants to protect plants and food against fungal pathogens: a review. ... associated with these chemicals have motivated researchers and cultivators to ... may be lower if the different compounds affect a different metabolic process.

  17. Separate and Combined Effects of Mentha piperata and Mentha pulegium Essential Oils and a Pathogenic Fungus Lecanicillium muscarium Against Aphis gossypii (Hemiptera: Aphididae).

    Science.gov (United States)

    Ebadollahi, Asgar; Davari, Mahdi; Razmjou, Jabrael; Naseri, Bahram

    2017-06-01

    In the present study, the toxicity of essential oils of Mentha piperata L. and Mentha pulegium L. and pathogenicity of Lecanicillium muscarium (Zare & Gams) were studied in the melon aphid, Aphis gossypii Glover. Analyses of the essential oils by GC-MS indicated limonene (27.28%), menthol (24.71%), menthone (14.01%), and carvol (8.46%) in the M. piperata essential oil and pulegone (73.44%), piperitenone (5.49%), decane (4.99%), and limonene (3.07%) in the essential oil of M. pulegium as the main components. Both essential oils and the pathogenic fungus had useful toxicity against A. gossypii. Probit analysis indicated LC50 values (lethal concentrations to kill 50% of population; 95% confidence limits in parentheses) of M. piperata and M. pulegium essential oils as 15.25 (12.25-19.56) and 23.13 (19.27-28.42) µl/liter air, respectively. Susceptibility to the pathogenic fungus increased with exposure time. Aphid mortality also increased when the essential oils were combined with L. muscarium, although the phenomena was additive rather than synergistic. Mycelial growth inhibition of L. muscarium exposed to the essential oils was also very low. Based on our results, M. piperata and M. pulegium essential oils and the pathogenic fungus L. muscarium have some potential for management of A. gossypii. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Redox activities and ROS, NO and phenylpropanoids production by axenically cultured intact olive seedling roots after interaction with a mycorrhizal or a pathogenic fungus.

    Directory of Open Access Journals (Sweden)

    Francisco Espinosa

    Full Text Available Roots of intact olive seedlings, axenically cultured, were alternatively placed in contact with Rhizophagus irregularis (mycorrhizal or Verticillim dahliae (pathogenic fungi. MeJA treatments were also included. In vivo redox activities in the apoplast of the intact roots (anion superoxide generation, superoxide dismutase and peroxidase activities were measured. All our results showed that apoplastic redox activities of intact seedling roots in contact with the compatible mycorrhizal fungus were clearly attenuated in comparison with the pathogenic fungus or treated with MeJA, even at the early stages of treatment used. Total phenolics, flavonoids and phenylpropanoid glycosides were also quantified. Roots in contact with the mycorrhizal fungus did not enhance the biosynthesis of phenolic compounds with respect to controls, while those in contact with the pathogenic one significantly enhanced the biosynthesis of all phenolic fractions measured. Reactive oxygen species and nitric oxid accumulation in roots were examined by fluorescence microscopy. All of them presented much higher accumulation in roots in contact with the pathogenic than with the mycorrhizal fungus. Altogether these results indicate that intact olive seedling roots clearly differentiated between mycorrhizal and pathogenic fungi, attenuating defense reactions against the first to facilitate its establishment, while inducing a strong and sustained defense reaction against the second. Both reactive oxygen and nitrogen species seemed to be involved in these responses from the first moments of contact. However, further investigations are required to clarify the proposed crosstalk between them and their respective roles in these responses since fluorescence images of roots revealed that reactive oxygen species were mainly accumulated in the apoplast (congruently with the measured redox activities in this compartment while nitric oxid was mainly stored in the cytosol.

  19. The promoting role of an isolate of dark-septate fungus on its host plant Saussurea involucrata Kar. et Kir.

    Science.gov (United States)

    Wu, Li-qin; Lv, Ya-li; Meng, Zhi-xia; Chen, Juan; Guo, Shun-Xing

    2010-02-01

    A dark-septate endophytic (DSE) fungus EF-37 was isolated from the roots of Saussurea involucrata Kar. et Kir., an endangered Chinese medicinal plant. The molecular identification of the fungus was based on internal transcribed spacer regions and the result showed that EF-37 was congeneric to Mycocentrospora. This study was conducted to clarify the influence of the root endophyte EF-37 on the host plant S. involucrata using material grown in a sterile culture bottle. After cultivation for 40 days, fungal hyphae were found to be branching repeatedly and forming "hyphae nets" in the epidermal layers. Significant differences were detected between the study groups in plant dry weight, plant height, root dry weight, shoot dry weight, and the number of hair root tips. There was a positive effect of endophyte EF-37 on plant root development, with results showing that cortical cells dissolved and formed aerate structures. There was a positive effect of endophyte EF-37 on plant growth, but chlorophyll fluorescence analysis showed that there were no significant differences between the study groups. In addition, analysis of the chemical composition of seedlings showed that the level of rutin was higher in plants cultivated with the EF-37 fungus compared to the controls. This study helps to establish a basis for germplasm conservation and for further investigation of the interaction between dark-septate fungi and this alpine plant.

  20. Changing fitness of a necrotrophic plant pathogen under increasing temperature.

    Science.gov (United States)

    Sabburg, Rosalie; Obanor, Friday; Aitken, Elizabeth; Chakraborty, Sukumar

    2015-08-01

    Warmer temperatures associated with climate change are expected to have a direct impact on plant pathogens, challenging crops and altering plant disease profiles in the future. In this study, we have investigated the effect of increasing temperature on the pathogenic fitness of Fusarium pseudograminearum, an important necrotrophic plant pathogen associated with crown rot disease of wheat in Australia. Eleven wheat lines with different levels of crown rot resistance were artificially inoculated with F. pseudograminearum and maintained at four diurnal temperatures 15/15°C, 20/15°C, 25/15°C and 28/15°C in a controlled glasshouse. To quantify the success of F. pseudograminearum three fitness measures, these being disease severity, pathogen biomass in stem base and flag leaf node, and deoxynivalenol (DON) in stem base and flag leaf node of mature plants were used. F. pseudograminearum showed superior overall fitness at 15/15°C, and this was reduced with increasing temperature. Pathogen fitness was significantly influenced by the level of crown rot resistance of wheat lines, but the influence of line declined with increasing temperature. Lines that exhibited superior crown rot resistance in the field were generally associated with reduced overall pathogen fitness. However, the relative performance of the wheat lines was dependent on the measure of pathogen fitness, and lines that were associated with one reduced measure of pathogen fitness did not always reduce another. There was a strong correlation between DON in stem base tissue and disease severity, but length of browning was not a good predictor of Fusarium biomass in the stem base. We report that a combination of host resistance and rising temperature will reduce pathogen fitness under increasing temperature, but further studies combining the effect of rising CO2 are essential for more realistic assessments. © 2015 John Wiley & Sons Ltd.

  1. Reciprocal trade of Carbon and Nitrogen at the root-fungus interface in ectomycorrhizal beech plants

    Science.gov (United States)

    Kaiser, Christina; Mayerhofer, Werner; Dietrich, Marlies; Gorka, Stefan; Schintlmeister, Arno; Reipert, Siegfried; Schweiger, Peter; Weidinger, Marieluise; Wiesenbauer, Julia; Martin, Victoria; Richter, Andreas; Woebken, Dagmar

    2017-04-01

    Plants deliver recently assimilated carbon (C) to mycorrhizal fungi, and receive nutrients, such as N and P, in exchange. A reciprocal exchange of C and nutrients between plants and mycorrhizal fungi (i.e., fungi which deliver more nutrients receive more plant C in return and vice versa) has been suggested for arbuscular mycorrhizal symbioses by some studies, but challenged by others. For ectomycorrhizal associations even less is known on how the exchange of C for nutrients is regulated, and whether it is based on reciprocity, or other controls. The aim of this study was to test the concept of reciprocal rewards between beech (Fagus sylvatica) and their associated ectomycorrhizal fungi on different scales, namely (a) across associations between individual root tips of beech and different fungal partners, and (b) at the subcellular scale at the plant-fungus interface. We exposed young beech trees associated with natural mycorrhizal fungal communities to a 13CO2 atmosphere and added 15N-labelled amino acids to a 'litter compartment', that mycorrhizal hyphae, but not plant roots could access. Plants were harvested within 2 days after application of 15N and less than one day after applying 13CO2. If the trading of C for N was reciprocal, we expect that 13C would be correlated to 15N across individual plant-fungal connections and at the subcellular scale within one mycorrhizal root tip, respectively. We collected individual mycorrhizal root-tips from 8 plants right after harvest, analyzed their 13C and 15N content by isotope-ratio mass spectrometry (EA-IRMS) and performed ITS sequencing to identify fungal communities associated with individual root tips. Selected mycorrhizal root tips were also prepared for nano-scale secondary ion mass spectrometry (NanoSIMS) to visualize the spatial distribution of 13C and 15N in cross-sections of mycorrhizal root-tips at the subcellular scale. Our results showed a significant, albeit weak correlation between 13C and 15N across

  2. Leucoagaricus gongylophorus produces diverse enzymes for the degradation of recalcitrant plant polymers in leaf-cutter ant fungus gardens.

    Science.gov (United States)

    Aylward, Frank O; Burnum-Johnson, Kristin E; Tringe, Susannah G; Teiling, Clotilde; Tremmel, Daniel M; Moeller, Joseph A; Scott, Jarrod J; Barry, Kerrie W; Piehowski, Paul D; Nicora, Carrie D; Malfatti, Stephanie A; Monroe, Matthew E; Purvine, Samuel O; Goodwin, Lynne A; Smith, Richard D; Weinstock, George M; Gerardo, Nicole M; Suen, Garret; Lipton, Mary S; Currie, Cameron R

    2013-06-01

    Plants represent a large reservoir of organic carbon comprised primarily of recalcitrant polymers that most metazoans are unable to deconstruct. Many herbivores gain access to nutrients in this material indirectly by associating with microbial symbionts, and leaf-cutter ants are a paradigmatic example. These ants use fresh foliar biomass as manure to cultivate gardens composed primarily of Leucoagaricus gongylophorus, a basidiomycetous fungus that produces specialized hyphal swellings that serve as a food source for the host ant colony. Although leaf-cutter ants are conspicuous herbivores that contribute substantially to carbon turnover in Neotropical ecosystems, the process through which plant biomass is degraded in their fungus gardens is not well understood. Here we present the first draft genome of L. gongylophorus, and, using genomic and metaproteomic tools, we investigate its role in lignocellulose degradation in the gardens of both Atta cephalotes and Acromyrmex echinatior leaf-cutter ants. We show that L. gongylophorus produces a diversity of lignocellulases in ant gardens and is likely the primary driver of plant biomass degradation in these ecosystems. We also show that this fungus produces distinct sets of lignocellulases throughout the different stages of biomass degradation, including numerous cellulases and laccases that likely play an important role in lignocellulose degradation. Our study provides a detailed analysis of plant biomass degradation in leaf-cutter ant fungus gardens and insight into the enzymes underlying the symbiosis between these dominant herbivores and their obligate fungal cultivar.

  3. Meroterpenoids with antiproliferative activity from a Hawaiian-plant associated fungus Peyronellaea coffeae-arabicae FT238

    Science.gov (United States)

    Three unusual polyketide-sesquiterpene metabolites peyronellins A-C (1-3), along with the new epoxyphomalin analog 11-dehydroxy epoxyphomalin A (4), have been isolated from the endophytic fungus Peyronellaea cof feae-arabicae FT238, which was isolated from the native Hawaiian plant Pritchardia lowre...

  4. Dihydroberkleasmin A: a new eremophilane sesquiterpenoid from the fermentation broth of the plant endophytic fungus Pestalotiopsis photiniae.

    Science.gov (United States)

    Yang, Xiao-Long; Zhang, Su; Zhu, Hua-Jie; Luo, Du-Qiang

    2011-02-23

    Dihydroberkleasmin A (1), a new ester-substituted sesquiterpenoid related to the eremophilane class, together with the known compound berkleasmin C (2), were isolated from the fermentation broth of the plant endophytic fungus Pestalotiopsis photiniae. The structure of dihydroberkleasmin A (1) was elucidated by extensive spectroscopic analysis. The stereochemistry was assigned by comparison of the NMR spectroscopic data with those of berkleasmin A.

  5. Dihydroberkleasmin A: A New Eremophilane Sesquiterpenoid from the Fermentation Broth of the Plant Endophytic Fungus Pestalotiopsis photiniae

    OpenAIRE

    Du-Qiang Luo; Su Zhang; Hua-Jie Zhu; Xiao-Long Yang

    2011-01-01

    Dihydroberkleasmin A (1), a new ester-substituted sesquiterpenoid related to the eremophilane class, together with the known compound berkleasmin C (2), were isolated from the fermentation broth of the plant endophytic fungus Pestalotiopsis photiniae. The structure of dihydroberkleasmin A (1) was elucidated by extensive spectroscopic analysis. The stereochemistry was assigned by comparison of the NMR spectroscopic data with those of berkleasmin A.

  6. Secondary Metabolites and Bioactivity of the Endophytic Fungus Phomopsis theicola from Taiwanese endemic plant

    Directory of Open Access Journals (Sweden)

    Yi Hsiao

    2016-03-01

    Full Text Available A new cytochalasan named as phomocytochalasin (1, together with five previously identified compounds, cytochalasin H, cytochalasin N, RKS-1778, dankasterone B, cyclo(L-Ile-L-Leu, were isolated from the solid fermentate of Phomopsis theicola BCRC 09F0213, an endophytic fungus isolated from the leaves of an endemic Formosan plant Litsea hypophaea Hayata . The structure of the new compound was established by spectroscopic methods, including UV, IR, HR-ESIMS, and extensive 1D- and 2D-NMR techniques. Among the isolates, cytochalasin N showed NO inhibitory activity with IC 50 values of 77.8 μM . Cytochalasin H showed the progesterone receptor (PR antagonism with the IC 50 value of 1.42 μM.

  7. Purification and Structural Analysis of a Selective Toxin Fraction Produced by the Plant Pathogen Setosphaeria turcica

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-hui; DONG Jin-gao; WANG Chao-hua; LI Zheng-ping

    2007-01-01

    Thirteen fractions from the pathogenic plant fungus Setosphaeria turcica race 1 were separated and collected using high performance liquid chromatography (HPLC). Their toxic activities were assayed through leaf puncturing on corn differentials (OH43, OH43Htl, OH43Ht2, and OH43HtN), and the results revealed that eight fractions were toxic and fraction 6 was specifically toxic to OH43Htl, which could be taken as a gene-selective toxin fraction. Fraction 6 was finely purified via HPLC and condensed by freeze desiccation. Its chemical structure was analyzed with EI-MS, IR, HMBC, 1H-NMR, and two-dimensional NMR. The results suggested that fraction 6 contained an unsaturated double bond, carbonyl and methylene groups with molecular weight of 142.

  8. Conidial Dihydroxynaphthalene Melanin of the Human Pathogenic Fungus Aspergillus fumigatus Interferes with the Host Endocytosis Pathway.

    Science.gov (United States)

    Thywißen, Andreas; Heinekamp, Thorsten; Dahse, Hans-Martin; Schmaler-Ripcke, Jeannette; Nietzsche, Sandor; Zipfel, Peter F; Brakhage, Axel A

    2011-01-01

    Aspergillus fumigatus is the most important air-borne fungal pathogen of humans. The interaction of the pathogen with the host's immune system represents a key process to understand pathogenicity. For elimination of invading microorganisms, they need to be efficiently phagocytosed and located in acidified phagolysosomes. However, as shown previously, A. fumigatus is able to manipulate the formation of functional phagolysosomes. Here, we demonstrate that in contrast to pigmentless pksP mutant conidia of A. fumigatus, the gray-green wild-type conidia inhibit the acidification of phagolysosomes of alveolar macrophages, monocyte-derived macrophages, and human neutrophil granulocytes. Therefore, this inhibition is independent of the cell type and applies to the major immune effector cells required for defense against A. fumigatus. Studies with melanin ghosts indicate that the inhibitory effect of wild-type conidia is due to their dihydroxynaphthalene (DHN)-melanin covering the conidia, whereas the hydrophobin RodA rodlet layer plays no role in this process. This is also supported by the observation that pksP conidia still exhibit the RodA hydrophobin layer, as shown by scanning electron microscopy. Mutants defective in different steps of the DHN-melanin biosynthesis showed stronger inhibition than pksP mutant conidia but lower inhibition than wild-type conidia. Moreover, A. fumigatus and A. flavus led to a stronger inhibition of phagolysosomal acidification than A. nidulans and A. terreus. These data indicate that a certain type of DHN-melanin that is different in the various Aspergillus species, is required for maximal inhibition of phagolysosomal acidification. Finally, we identified the vacuolar ATPase (vATPase) as potential target for A. fumigatus based on the finding that addition of bafilomycin which inhibits vATPase, led to complete inhibition of the acidification whereas the fusion of phagosomes containing wild-type conidia and lysosomes was not affected.

  9. Conidial Dihydroxynaphthalene Melanin of the Human Pathogenic Fungus Aspergillus fumigatus Interferes with the Host Endocytosis Pathway

    Science.gov (United States)

    Thywißen, Andreas; Heinekamp, Thorsten; Dahse, Hans-Martin; Schmaler-Ripcke, Jeannette; Nietzsche, Sandor; Zipfel, Peter F.; Brakhage, Axel A.

    2011-01-01

    Aspergillus fumigatus is the most important air-borne fungal pathogen of humans. The interaction of the pathogen with the host's immune system represents a key process to understand pathogenicity. For elimination of invading microorganisms, they need to be efficiently phagocytosed and located in acidified phagolysosomes. However, as shown previously, A. fumigatus is able to manipulate the formation of functional phagolysosomes. Here, we demonstrate that in contrast to pigmentless pksP mutant conidia of A. fumigatus, the gray-green wild-type conidia inhibit the acidification of phagolysosomes of alveolar macrophages, monocyte-derived macrophages, and human neutrophil granulocytes. Therefore, this inhibition is independent of the cell type and applies to the major immune effector cells required for defense against A. fumigatus. Studies with melanin ghosts indicate that the inhibitory effect of wild-type conidia is due to their dihydroxynaphthalene (DHN)-melanin covering the conidia, whereas the hydrophobin RodA rodlet layer plays no role in this process. This is also supported by the observation that pksP conidia still exhibit the RodA hydrophobin layer, as shown by scanning electron microscopy. Mutants defective in different steps of the DHN-melanin biosynthesis showed stronger inhibition than pksP mutant conidia but lower inhibition than wild-type conidia. Moreover, A. fumigatus and A. flavus led to a stronger inhibition of phagolysosomal acidification than A. nidulans and A. terreus. These data indicate that a certain type of DHN-melanin that is different in the various Aspergillus species, is required for maximal inhibition of phagolysosomal acidification. Finally, we identified the vacuolar ATPase (vATPase) as potential target for A. fumigatus based on the finding that addition of bafilomycin which inhibits vATPase, led to complete inhibition of the acidification whereas the fusion of phagosomes containing wild-type conidia and lysosomes was not affected. PMID

  10. Host-Pathogen Interactions: VII. Plant Pathogens Secrete Proteins which Inhibit Enzymes of the Host Capable of Attacking the Pathogen.

    Science.gov (United States)

    Albersheim, P; Valent, B S

    1974-05-01

    The results presented demonstrate that microbial pathogens of plants have the ability to secrete proteins which effectively inhibit an enzyme synthesized by the host; an enzyme whose substrate is a constituent of the cell wall of the pathogen. The system in which this was discovered is the anthracnose-causing fungal pathogen (Colletotrichum lindemuthianum) and its host, the French bean (Phaseolus vulgaris). An endo-beta-1, 3-glucanase present in the bean leaves is specifically inhibited by a protein secreted by C. lindemuthianum. The cell walls of C. lindemuthianum are shown to be composed largely of a 1, 3-glucan.

  11. Ascochlorin derivatives from the leafhopper pathogenic fungus Microcera sp. BCC 17074.

    Science.gov (United States)

    Isaka, Masahiko; Yangchum, Arunrat; Supothina, Sumalee; Laksanacharoen, Pattiyaa; Jennifer Luangsa-Ard, J; Hywel-Jones, Nigel L

    2015-01-01

    Two new ascochlorin derivatives, nectchlorins A (1) and B (2), together with eight known compounds (3-10), were isolated from cultures of the leafhopper pathogen Microcera sp. BCC 17074. The structures were elucidated on the basis of NMR spectroscopic and mass spectrometry data. The absolute configuration of 2 was determined by application of the modified Mosher's method. The absolute configuration of LL-Z 1272α epoxide (9), which is a plausible biosynthetic precursor of ascochlorins, was established by chemical correlations. Cytotoxic activities of these ascochlorin derivatives were evaluated.

  12. Beyond animals and plants: dynamic maternal effects in the fungus Neurospora crassa.

    Science.gov (United States)

    Zimmerman, K C K; Levitis, D A; Pringle, A

    2016-07-01

    Maternal effects are widely documented in animals and plants, but not in fungi or other eukaryotes. A principal cause of maternal effects is asymmetrical parental investment in a zygote, creating greater maternal vs. paternal influence on offspring phenotypes. Asymmetrical investments are not limited to animals and plants, but are also prevalent in fungi and groups including apicomplexans, dinoflagellates and red algae. Evidence suggesting maternal effects among fungi is sparse and anecdotal. In an experiment designed to test for maternal effects across sexual reproduction in the model fungus Neurospora crassa, we measured offspring phenotypes from crosses of all possible pairs of 22 individuals. Crosses encompassed reciprocals of 11 mating-type 'A' and 11 mating-type 'a' wild strains. After controlling for the genetic and geographic distances between strains in any individual cross, we found strong evidence for maternal control of perithecia (sporocarp) production, as well as maternal effects on spore numbers and spore germination. However, both parents exert equal influence on the percentage of spores that are pigmented and size of pigmented spores. We propose a model linking the stage-specific presence or absence of maternal effects to cellular developmental processes: effects appear to be mediated primarily through the maternal cytoplasm, and, after spore cell walls form, maternal influence on spore development is limited. Maternal effects in fungi, thus far largely ignored, are likely to shape species' evolution and ecologies. Moreover, the association of anisogamy and maternal effects in a fungus suggests maternal effects may also influence the biology of other anisogamous eukaryotes. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  13. Preservation of in vitro cultures of the mite pathogenic fungus Neozygites tanajoae.

    Science.gov (United States)

    Delalibera, Italo; Humber, Richard A; Hajek, Ann E

    2004-08-01

    Neozygites tanajoae has recently been described as a new fungal pathogen distinct from Neozygites floridana. This pathogen is currently being used as a classical biological control agent against the cassava green mite, Mononychellus tanajoa (Bondar), in Africa. Neozygites tanajoae is a particularly fastidious species, and in vitro cultures of isolates from Brazil and Africa have only recently been established. In this study, the efficacy of several cryoprotectants at different exposure times, cooling rates, and warming rates for protecting hyphal bodies of N. tanajoae during cryopreservation was investigated. A protocol for preservation of cultures of N. tanajoae at ultra-low temperatures of -80 degrees C or -196 degrees C, using 1% trehalose + 2% dimethyl sulfoxide as cryoprotective agents, is described in detail. In this study, we demonstrate that N. tanajoae differs remarkably from N. floridana (isolates ARSEF 662 and ARSEF 5376) in the ability to withstand the stress of cold temperature (4 degrees C) and cryopreservation. In vitro cultures of the 2 N. floridana isolates remained viable at 4 degrees C for up to 47 d; however, cultures of N. tanajoae did not survive this temperature for 4 d. Cryopreservation methods successful for N. tanajoae isolates are not suitable for N. floridana and are unusual in comparison to those for many fungi.

  14. Microevolutionary traits and comparative population genomics of the emerging pathogenic fungus Cryptococcus gattii

    Science.gov (United States)

    Voelz, Kerstin; Henk, Daniel A.; Johnston, Simon A.; May, Robin C.

    2016-01-01

    Emerging fungal pathogens cause an expanding burden of disease across the animal kingdom, including a rise in morbidity and mortality in humans. Yet, we currently have only a limited repertoire of available therapeutic interventions. A greater understanding of the mechanisms of fungal virulence and of the emergence of hypervirulence within species is therefore needed for new treatments and mitigation efforts. For example, over the past decade, an unusual lineage of Cryptococcus gattii, which was first detected on Vancouver Island, has spread to the Canadian mainland and the Pacific Northwest infecting otherwise healthy individuals. The molecular changes that led to the development of this hypervirulent cryptococcal lineage remain unclear. To explore this, we traced the history of similar microevolutionary events that can lead to changes in host range and pathogenicity. Here, we detail fine-resolution mapping of genetic differences between two highly related Cryptococcus gattii VGIIc isolates that differ in their virulence traits (phagocytosis, vomocytosis, macrophage death, mitochondrial tubularization and intracellular proliferation). We identified a small number of single site variants within coding regions that potentially contribute to variations in virulence. We then extended our methods across multiple lineages of C. gattii to study how selection is acting on key virulence genes within different lineages. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’. PMID:28080992

  15. Clonality despite sex: the evolution of host-associated sexual neighborhoods in the pathogenic fungus Penicillium marneffei.

    Directory of Open Access Journals (Sweden)

    Daniel A Henk

    Full Text Available Molecular genetic approaches typically detect recombination in microbes regardless of assumed asexuality. However, genetic data have shown the AIDS-associated pathogen Penicillium marneffei to have extensive spatial genetic structure at local and regional scales, and although there has been some genetic evidence that a sexual cycle is possible, this haploid fungus is thought to be genetically, as well as morphologically, asexual in nature because of its highly clonal population structure. Here we use comparative genomics, experimental mixed-genotype infections, and population genetic data to elucidate the role of recombination in natural populations of P. marneffei. Genome wide comparisons reveal that all the genes required for meiosis are present in P. marneffei, mating type genes are arranged in a similar manner to that found in other heterothallic fungi, and there is evidence of a putatively meiosis-specific mutational process. Experiments suggest that recombination between isolates of compatible mating types may occur during mammal infection. Population genetic data from 34 isolates from bamboo rats in India, Thailand and Vietnam, and 273 isolates from humans in China, India, Thailand, and Vietnam show that recombination is most likely to occur across spatially and genetically limited distances in natural populations resulting in highly clonal population structure yet sexually reproducing populations. Predicted distributions of three different spatial genetic clusters within P. marneffei overlap with three different bamboo rat host distributions suggesting that recombination within hosts may act to maintain population barriers within P. marneffei.

  16. Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

    Directory of Open Access Journals (Sweden)

    Kelly Ishida

    2014-04-01

    Full Text Available The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus .

  17. Silver nanoparticle production by the fungus Fusarium oxysporum: nanoparticle characterisation and analysis of antifungal activity against pathogenic yeasts

    Science.gov (United States)

    Ishida, Kelly; Cipriano, Talita Ferreira; Rocha, Gustavo Miranda; Weissmüller, Gilberto; Gomes, Fabio; Miranda, Kildare; Rozental, Sonia

    2013-01-01

    The microbial synthesis of nanoparticles is a green chemistry approach that combines nanotechnology and microbial biotechnology. The aim of this study was to obtain silver nanoparticles (SNPs) using aqueous extract from the filamentous fungus Fusarium oxysporum as an alternative to chemical procedures and to evaluate its antifungal activity. SNPs production increased in a concentration-dependent way up to 1 mM silver nitrate until 30 days of reaction. Monodispersed and spherical SNPs were predominantly produced. After 60 days, it was possible to observe degenerated SNPs with in additional needle morphology. The SNPs showed a high antifungal activity against Candida and Cryptococcus , with minimum inhibitory concentration values ≤ 1.68 µg/mL for both genera. Morphological alterations of Cryptococcus neoformans treated with SNPs were observed such as disruption of the cell wall and cytoplasmic membrane and lost of the cytoplasm content. This work revealed that SNPs can be easily produced by F. oxysporum aqueous extracts and may be a feasible, low-cost, environmentally friendly method for generating stable and uniformly sized SNPs. Finally, we have demonstrated that these SNPs are active against pathogenic fungi, such as Candida and Cryptococcus . PMID:24714966

  18. EFFECT OF CHRONIC RADIATION ON PLANT-PATHOGEN INTERACTIONS IN 30-KM CHERNOBYL ZONE

    Directory of Open Access Journals (Sweden)

    Dmitriev A.

    2012-08-01

    Full Text Available It was established in pot experiments that infection with powdery mildew (Erysiphe graminis DC. f. sp. tritici Em. Marchal and brown rust (Puccinia triticana Erikss. & Henn. of three wheat (Triticum aestivum L. cultivars ('Mironovskaya 808', 'Polesskay 70', and 'Kiyanka' grown from seeds, collected in the Chernobyl exclusion zone, was 1.5–2.0 times higher than that of plants grown from control seeds. On filed plots in the Chernobyl zone, wheat plant resistance to biotic stress was reduced. At artificial infection with brown rusts, the disease development was enhanced on plots with increased radiation background. One of the mechanisms of declined phytoimmunity potential under the action of low doses of chronic irradiation is evidently a reduced activity of plant proteinase inhibitors. Thus, in wheat and rye (Secale cereale L., cv. ‘Saratovskaya’ kernels, their activity reduced by 35–60% as compared to control. Active form and race formation in the population of the grass stem rust causal agent (Puccinia graminis Pers. was observed in the Chernobyl zone. A “new” population of this fungus with high frequency of more virulent clones than in other Ukraine regions was distinguished. The results obtained independently in greenhouse and field trials performed in the Chernobyl zone demonstrated radiation stress influence on the pathogen–plant system. They indicate a necessity of monitoring the microevolutionary processes occurring in both plants and their pathogens under conditions of technogenic stresses.

  19. Molecular diversity at the plant-pathogen interface.

    Science.gov (United States)

    McDowell, John M; Simon, Stacey A

    2008-01-01

    Plants have evolved a robust innate immune system that exhibits striking similarities as well as significant differences with various metazoan innate immune systems. For example, plants are capable of perceiving pathogen-associated molecular patterns through pattern recognition receptors that bear structural similarities to animal Toll-like receptors. In addition, plants have evolved a second surveillance system based on cytoplasmic "NB-LRR" proteins (nucleotide-binding, leucine-rich repeat) that are structurally similar to animal nucleotide-binding and oligomerization domain (NOD)-like receptors. Plant NB-LRR proteins do not detect PAMPs; rather, they perceive effector proteins that pathogens secrete into plant cells to promote virulence. This review summarizes the current state of knowledge about the molecular functionality and evolution of these immune surveillance genes.

  20. Interaction between TATA-Binding Protein (TBP) and Multiprotein Bridging Factor-1 (MBF1) from the Filamentous Insect Pathogenic Fungus Beauveria bassiana

    OpenAIRE

    Chi Song; Almudena Ortiz-Urquiza; Sheng-Hua Ying; Jin-Xia Zhang; Nemat O Keyhani

    2015-01-01

    TATA-binding protein (TBP) is a ubiquitous component of eukaryotic transcription factors that acts to nucleate assembly and position pre-initiation complexes. Multiprotein bridging factor 1 (MBF1) is thought to interconnect TBP with gene specific transcriptional activators, modulating transcriptional networks in response to specific signal and developmental programs. The insect pathogen, Beauveria bassiana, is a cosmopolitan fungus found in most ecosystems where it acts as an important regula...

  1. Comprehensive proteomic analysis of the wheat pathogenic fungus Zymoseptoria tritici

    DEFF Research Database (Denmark)

    Yang, Fen; Yin, Qi

    2016-01-01

    Zymoseptoria tritici causes Septoria tritici blotch disease of wheat. To obtain a comprehensive protein dataset of this fungal pathogen, proteomes of Z. tritici growing in nutrient-limiting and rich media and in vivo at a late stage of wheat infection were fractionated by 1D gel or strong cation...... exchange (SCX) chromatography and analyzed by LC-MS/MS. A total of 5731, 5376 and 3168 Z. tritici proteins were confidently identified from these conditions, respectively. Of these in vitro and in planta proteins, 9 and 11% were predicted to contain signal peptides, respectively. Functional classification...... analysis revealed the proteins were involved in the various cellular activities. Comparison of three distinct protein expression profiles demonstrates the elevated carbohydrate, lipid and secondary metabolisms, transport, protein processing and energy production specifically in the host environment...

  2. A Bilobalide-Producing Endophytic Fungus, Pestalotiopsis uvicola from Medicinal Plant Ginkgo biloba.

    Science.gov (United States)

    Qian, Yi-Xin; Kang, Ji-Chuan; Luo, Yi-Kai; Zhao, Jun-Jie; He, Jun; Geng, Kun

    2016-08-01

    For screening bilobalide (BB)-producing endophytic fungi from medicinal plant Ginkgo biloba, a total of 57 fungal isolates were isolated from the internal stem, root, leaf, and bark of the plant G. biloba. Fermentation processes using BB-producing fungi other than G. biloba may become a novel way to produce BB, which is a terpene trilactones exhibiting neuroprotective effects. In this study, a BB-producing endophytic fungal strain GZUYX13 was isolated from the leaves of G. biloba grown in the campus of Guizhou University, Guiyang city, Guizhou province, China. The strain produced BB when grown in potato dextrose liquid medium. The amount of BB produced by this endophytic fungus was quantified to be 106 μg/L via high-performance liquid chromatography (HPLC), substantially lower than that produced by the host tissue. The fungal BB which was analyzed by thin layer chromatography (TLC) and HPLC was proven to be identical to authentic BB. The strain GZUYX13 was identified as Pestalotiopsis uvicola via morphology and ITS rDNA phylogeny. To the best of our knowledge, this is the first report concerning the isolation and identification of endophytic BB-producing Pestalotiopsis spp. from the host plant, which further proved that endophytic fungi have the potential to produce bioactive compounds.

  3. Short Interspersed Nuclear Element (SINE) Sequences in the Genome of the Human Pathogenic Fungus Aspergillus fumigatus Af293.

    Science.gov (United States)

    Kanhayuwa, Lakkhana; Coutts, Robert H A

    2016-01-01

    Novel families of short interspersed nuclear element (SINE) sequences in the human pathogenic fungus Aspergillus fumigatus, clinical isolate Af293, were identified and categorised into tRNA-related and 5S rRNA-related SINEs. Eight predicted tRNA-related SINE families originating from different tRNAs, and nominated as AfuSINE2 sequences, contained target site duplications of short direct repeat sequences (4-14 bp) flanking the elements, an extended tRNA-unrelated region and typical features of RNA polymerase III promoter sequences. The elements ranged in size from 140-493 bp and were present in low copy number in the genome and five out of eight were actively transcribed. One putative tRNAArg-derived sequence, AfuSINE2-1a possessed a unique feature of repeated trinucleotide ACT residues at its 3'-terminus. This element was similar in sequence to the I-4_AO element found in A. oryzae and an I-1_AF long nuclear interspersed element-like sequence identified in A. fumigatus Af293. Families of 5S rRNA-related SINE sequences, nominated as AfuSINE3, were also identified and their 5'-5S rRNA-related regions show 50-65% and 60-75% similarity to respectively A. fumigatus 5S rRNAs and SINE3-1_AO found in A. oryzae. A. fumigatus Af293 contains five copies of AfuSINE3 sequences ranging in size from 259-343 bp and two out of five AfuSINE3 sequences were actively transcribed. Investigations on AfuSINE distribution in the fungal genome revealed that the elements are enriched in pericentromeric and subtelomeric regions and inserted within gene-rich regions. We also demonstrated that some, but not all, AfuSINE sequences are targeted by host RNA silencing mechanisms. Finally, we demonstrated that infection of the fungus with mycoviruses had no apparent effects on SINE activity.

  4. Plant cell wall-degrading enzymes and their secretion in plant-pathogenic fungi.

    Science.gov (United States)

    Kubicek, Christian P; Starr, Trevor L; Glass, N Louise

    2014-01-01

    Approximately a tenth of all described fungal species can cause diseases in plants. A common feature of this process is the necessity to pass through the plant cell wall, an important barrier against pathogen attack. To this end, fungi possess a diverse array of secreted enzymes to depolymerize the main structural polysaccharide components of the plant cell wall, i.e., cellulose, hemicellulose, and pectin. Recent advances in genomic and systems-level studies have begun to unravel this diversity and have pinpointed cell wall-degrading enzyme (CWDE) families that are specifically present or enhanced in plant-pathogenic fungi. In this review, we discuss differences between the CWDE arsenal of plant-pathogenic and non-plant-pathogenic fungi, highlight the importance of individual enzyme families for pathogenesis, illustrate the secretory pathway that transports CWDEs out of the fungal cell, and report the transcriptional regulation of expression of CWDE genes in both saprophytic and phytopathogenic fungi.

  5. Bacteriocins active against plant pathogenic bacteria.

    Science.gov (United States)

    Grinter, Rhys; Milner, Joel; Walker, Daniel

    2012-12-01

    Gram-negative phytopathogens cause significant losses in a diverse range of economically important crop plants. The effectiveness of traditional countermeasures, such as the breeding and introduction of resistant cultivars, is often limited by the dearth of available sources of genetic resistance. An alternative strategy to reduce loss to specific bacterial phytopathogens is to use narrow-spectrum protein antibiotics such as colicin-like bacteriocins as biocontrol agents. A number of colicin-like bacteriocins active against phytopathogenic bacteria have been described previously as have strategies for their application to biocontrol. In the present paper, we discuss these strategies and our own recent work on the identification and characterization of candidate bacteriocins and how these potent and selective antimicrobial agents can be effectively applied to the control of economically important plant disease.

  6. Increase of Fungal Pathogenicity and Role of Plant Glutamine in Nitrogen-Induced Susceptibility (NIS) To Rice Blast

    Science.gov (United States)

    Huang, Huichuan; Nguyen Thi Thu, Thuy; He, Xiahong; Gravot, Antoine; Bernillon, Stéphane; Ballini, Elsa; Morel, Jean-Benoit

    2017-01-01

    Highlight  Modifications in glutamine synthetase OsGS1-2 expression and fungal pathogenicity underlie nitrogen-induced susceptibility to rice blast. Understanding why nitrogen fertilization increase the impact of many plant diseases is of major importance. The interaction between Magnaporthe oryzae and rice was used as a model for analyzing the molecular mechanisms underlying Nitrogen-Induced Susceptibility (NIS). We show that our experimental system in which nitrogen supply strongly affects rice blast susceptibility only slightly affects plant growth. In order to get insights into the mechanisms of NIS, we conducted a dual RNA-seq experiment on rice infected tissues under two nitrogen fertilization regimes. On the one hand, we show that enhanced susceptibility was visible despite an over-induction of defense gene expression by infection under high nitrogen regime. On the other hand, the fungus expressed to high levels effectors and pathogenicity-related genes in plants under high nitrogen regime. We propose that in plants supplied with elevated nitrogen fertilization, the observed enhanced induction of plant defense is over-passed by an increase in the expression of the fungal pathogenicity program, thus leading to enhanced susceptibility. Moreover, some rice genes implicated in nitrogen recycling were highly induced during NIS. We further demonstrate that the OsGS1-2 glutamine synthetase gene enhances plant resistance to M. oryzae and abolishes NIS and pinpoint glutamine as a potential key nutrient during NIS. PMID:28293247

  7. Evidence that the Human Pathogenic Fungus Cryptococcus neoformans var. grubii May Have Evolved in Africa

    Science.gov (United States)

    Litvintseva, Anastasia P.; Carbone, Ignazio; Rossouw, Jenny; Thakur, Rameshwari; Govender, Nelesh P.; Mitchell, Thomas G.

    2011-01-01

    Most of the species of fungi that cause disease in mammals, including Cryptococcus neoformans var. grubii (serotype A), are exogenous and non-contagious. Cryptococcus neoformans var. grubii is associated worldwide with avian and arboreal habitats. This airborne, opportunistic pathogen is profoundly neurotropic and the leading cause of fungal meningitis. Patients with HIV/AIDS have been ravaged by cryptococcosis – an estimated one million new cases occur each year, and mortality approaches 50%. Using phylogenetic and population genetic analyses, we present evidence that C. neoformans var. grubii may have evolved from a diverse population in southern Africa. Our ecological studies support the hypothesis that a few of these strains acquired a new environmental reservoir, the excreta of feral pigeons (Columba livia), and were globally dispersed by the migration of birds and humans. This investigation also discovered a novel arboreal reservoir for highly diverse strains of C. neoformans var. grubii that are restricted to southern Africa, the mopane tree (Colophospermum mopane). This finding may have significant public health implications because these primal strains have optimal potential for evolution and because mopane trees contribute to the local economy as a source of timber, folkloric remedies and the edible mopane worm. PMID:21589919

  8. Salamanders increase their feeding activity when infected with the pathogenic chytrid fungus Batrachochytrium dendrobatidis.

    Science.gov (United States)

    Hess, Alexandra; McAllister, Caroline; DeMarchi, Joseph; Zidek, Makenzie; Murone, Julie; Venesky, Matthew D

    2015-10-27

    Immune function is a costly line of defense against parasitism. When infected with a parasite, hosts frequently lose mass due to these costs. However, some infected hosts (e.g. highly resistant individuals) can clear infections with seemingly little fitness losses, but few studies have tested how resistant hosts mitigate these costly immune defenses. We explored this topic using eastern red-backed salamanders Plethodon cinereus and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Bd is generally lethal for amphibians, and stereotypical symptoms of infection include loss in mass and deficits in feeding. However, individuals of P. cinereus can clear their Bd infections with seemingly few fitness costs. We conducted an experiment in which we repeatedly observed the feeding activity of Bd-infected and non-infected salamanders. We found that Bd-infected salamanders generally increased their feeding activity compared to non-infected salamanders. The fact that we did not observe any differences in mass change between the treatments suggests that increased feeding might help Bd-infected salamanders minimize the costs of an effective immune response.

  9. A functional and structural study of the major metalloprotease secreted by the pathogenic fungus Aspergillus fumigatus.

    Science.gov (United States)

    Fernández, Daniel; Russi, Silvia; Vendrell, Josep; Monod, Michel; Pallarès, Irantzu

    2013-10-01

    Fungalysins are secreted fungal peptidases with the ability to degrade the extracellular matrix proteins elastin and collagen and are thought to act as virulence factors in diseases caused by fungi. Fungalysins constitute a unique family among zinc-dependent peptidases that bears low sequence similarity to known bacterial peptidases of the thermolysin family. The crystal structure of the archetype of the fungalysin family, Aspergillus fumigatus metalloprotease (AfuMep), has been obtained for the first time. The 1.8 Å resolution structure of AfuMep corresponds to that of an autoproteolyzed proenzyme with separate polypeptide chains corresponding to the N-terminal prodomain in a binary complex with the C-terminal zinc-bound catalytic domain. The prodomain consists of a tandem of cystatin-like folds whose C-terminal end is buried into the active-site cleft of the catalytic domain. The catalytic domain harbouring the key catalytic zinc ion and its ligands, two histidines and one glutamic acid, undergoes a conspicuous rearrangement of its N-terminal end during maturation. One key positively charged amino-acid residue and the C-terminal disulfide bridge appear to contribute to its structural-functional properties. Thus, structural, biophysical and biochemical analysis were combined to provide a deeper comprehension of the underlying properties of A. fumigatus fungalysin, serving as a framework for the as yet poorly known metallopeptidases from pathogenic fungi.

  10. Evidence that the human pathogenic fungus Cryptococcus neoformans var. grubii may have evolved in Africa.

    Directory of Open Access Journals (Sweden)

    Anastasia P Litvintseva

    Full Text Available Most of the species of fungi that cause disease in mammals, including Cryptococcus neoformans var. grubii (serotype A, are exogenous and non-contagious. Cryptococcus neoformans var. grubii is associated worldwide with avian and arboreal habitats. This airborne, opportunistic pathogen is profoundly neurotropic and the leading cause of fungal meningitis. Patients with HIV/AIDS have been ravaged by cryptococcosis--an estimated one million new cases occur each year, and mortality approaches 50%. Using phylogenetic and population genetic analyses, we present evidence that C. neoformans var. grubii may have evolved from a diverse population in southern Africa. Our ecological studies support the hypothesis that a few of these strains acquired a new environmental reservoir, the excreta of feral pigeons (Columba livia, and were globally dispersed by the migration of birds and humans. This investigation also discovered a novel arboreal reservoir for highly diverse strains of C. neoformans var. grubii that are restricted to southern Africa, the mopane tree (Colophospermum mopane. This finding may have significant public health implications because these primal strains have optimal potential for evolution and because mopane trees contribute to the local economy as a source of timber, folkloric remedies and the edible mopane worm.

  11. Pathogenic amoebae in power-plant cooling lakes. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Tyndall, R.L.; Willaert, E.; Stevens, A.R.

    1981-06-01

    Cooling waters and associated algae and sediments from four northern and four southern/western electric power plants were tested for the presence of pathogenic amoebae. Unheated control waters and algae/sediments from four northern and five southern/western sites were also tested. When comparing results from the test versus control sites, a significantly higher proportion (P less than or equal to 0.05) of the samples from the test sites were positive for thermophilic amoeba, thermophilic Naegleria and pathogenic Naegleria. The difference in number of samples positive for thermophilic Naegleria between heated and unheated waters, however, was attributable predominantly to the northern waters and algae/sediments. While two of four northern test sites yielded pathogenic Naegleria, seven of the eight isolates were obtained from one site. Seasonality effects relative to the isolation of the pathogen were also noted at this site. One pathogen was isolated from a southwestern test site. Pathogens were not isolated from any control sites. Some of the pathogenic isolates were analyzed serologically and classified as pathogenic Naegleria fowleri. Salinity, pH, conductivity, and bacteriological profiles did not obviously correlate with the presence or absence of pathogenic Naegleria. While thermal addition was significantly associated with the presence of thermophilic Naegleria (P less than or equal to 0.05), the data implicate other as yet undefined parameters associated with the presence of the pathogenic thermophile. Until further delineation of these parameters is effected, generalizations cannot be made concerning the effect of thermal impact on the growth of pathogenic amoeba in a particular cooling system.

  12. Effect of Kelp Residue Microbial Fertilizer on Eco-Control Peanut Pathogenic Fungus Aspergillus Parasiticus 1

    Institute of Scientific and Technical Information of China (English)

    Wei Xiao; Peisheng Yan

    2016-01-01

    Ecological prevention and control of plant disease is very important in sustainable agriculture. Adjusting soil pH value and fertilizing organic microbial fertilizer are two effective measures in this process. Kelp residue contains a large amount of organic compounds and alkaline metal ions. The bio⁃control Bacillus amyloliquefaciens strain Hitwh⁃BA2 was inoculated into kelp residue medium to produce kelp residue microbial fertilizer. Acidic soil and alkaline soil were used to study the effect of kelp residue microbial fertilizer on soil pH and soil suppressive activity. Tip⁃culture method was used to determine soil leachate suppressive activity, which characterized the soil suppressive activity. Results showed that fertilizing kelp residue microbial fertilizer had increased the soil pH and soil suppressive ability significantly, which was verified by peanut validation experiments as well. Peanut potting experiments proved that fertilizing kelp residue microbial fertilizer not only improved the yield of peanuts obviously, but also reduced the amount of Aspergillus parasiticus 95 in peanut geocarposphere soil significantly. Results also showed that fertilizing kelp residue microbial fertilizer was effective in reducing A. parasiticus 95 infection rate. So the kelp residue microbial fertilizer has good potential application prospect on ecological prevention and control of plant disease.

  13. Antifungal activity of diketopiperazines and stilbenes against plant pathogenic fungi in vitro.

    Science.gov (United States)

    Kumar, S Nishanth; Nambisan, Bala

    2014-01-01

    The present study aimed to investigate antifungal activity of a stilbene and diketopiperazine compounds against plant pathogenic fungi, including Phytophthora capsici, P. colocasiae, Botrytis cinerea and Colletotrichum gloeosporioides. Minimal inhibition concentrations (MIC) and minimal fungicidal concentrations (MFC) of stilbenes and diketopiperazines for each fungus were determined using microplate method. Best activity was recorded by stilbenes against P. capsici and P. colocasiae. All four test compounds were effective in inhibiting different stages of the life cycle of test fungi. Stilbenes were more effective than diketopiperazines in inhibiting mycelial growth and inhibiting different stages of the life cycle of P. capsici and P. colocasiae. Rupture of released zoospores induced by stilbenes was reduced by addition of 100 mM glucose. The effects of stilbenes on mycelial growth and zoospore release, but not zoospore rupture, were reduced largely when pH value was above 7. In addition, stilbenes were investigated for its antifungal stability against Phytophthora sp. The results showed that stilbenes maintained strong fungistatic activity over a wide pH range (pH 4–9) and temperature range (70–120 °C). The compound stilbenes exhibited strong and stable broad-spectrum antifungal activity, and had a significant fungicidal effect on fungal cells. Results from prebiocontrol evaluations performed to date are probably useful in the search for alternative approaches to controlling serious plant pathogens.

  14. Patogenicidade de Beauveria bassiana ao psilídeo Diaphorina citri e compatibilidade do fungo com produtos fitossanitários Beauveria bassiana pathogenicity to Diaphorina citri and compatibility of the fungus with phytosanitary products

    Directory of Open Access Journals (Sweden)

    Ana Paula Ferreira Pinto

    2012-12-01

    Full Text Available O objetivo deste trabalho foi avaliar a patogenicidade de Beauveria bassiana a ninfas de Diaphorina citri (Hemiptera: Psyllidae e verificar a compatibilidade do fungo com produtos fitossanitários e sua persistência em plantas de citros. Ninfas de D. citri foram pulverizadas com B. bassiana, nas concentrações 5x10(6, 1x10(7, 5x10(7, 1x10(8, 5x10(8 e 1x10(9 conídios mL-1, para determinação da concentração letal. Para avaliação da compatibilidade do fungo com produtos fitossanitários, extrato de nim e cinco inseticidas de quatro grupos químicos diferentes foram incorporados individualmente ao meio de cultura BDA em que o fungo foi cultivado. Avaliaram-se o crescimento vegetativo, a esporulação e a viabilidade do entomopatógeno. Plantas de citros, mantidas em casa de vegetação, foram tratadas primeiramente com os produtos fitossanitários e depois com o entomopatógeno. Avaliaram-se os tempos de exposição de 24 horas e de 7 e 14 dias. O fungo foi patogênico às ninfas de D. citri; a CL50 foi de 0,4x10(7 e a CL90 de 6,7x10(7 conidios mL-1, no décimo dia de avaliação. Em laboratório, os produtos fitosssanitários reduzem o crescimento do fungo. Em casa de vegetação, os produtos não afetam a sobrevivência do fungo nas plantas de citros.The objective of this work was to evaluate the pathogenicity of Beauveria bassiana to Diaphorina citri (Hemiptera: Psyllidae nymphs, and to check the compatibility of the fungus with phytosanitary products, and its persistence in citrus plants. Nymphs of D. citri were sprayed with B. bassiana in the concentrations 5x10(6, 1x10(7, 5x10(7, 1x10(8, 5x10(8 and 1x10(9 conidia mL-1 for lethal concentration determination. In order to evaluate the compatibility of the phytosanitary products with the fungus, neem extract and five insecticides of four different chemical groups were individually added to PDA culture medium, in which the fungus was cultivated. Vegetative growth, sporulation and viability

  15. Plant integrity: an important factor in plant-pathogen interactions

    DEFF Research Database (Denmark)

    Orlowska, Elzbieta Zofia; Llorente, Briardo; Cvitanich, Cristina

    2013-01-01

    the hemibiotrophic oomycete pathogen Phytophthora infestans. Furthermore, in the Sarpo Mira–P. infestans interactions, the plant’s meristems, the stalks or both, seem to be associated with the development of the hypersensitive response and both the plant’s roots and shoots contain antimicrobial compounds when...

  16. Effects of substrate, ant and fungal species on plant fiber degradation in a fungus-gardening ant symbiosis.

    Science.gov (United States)

    DeMilto, Alexandria M; Rouquette, Monte; Mueller, Ulrich G; Kellner, Katrin; Seal, Jon N

    2017-04-01

    Fungus-gardening or attine ants have outsourced most of their digestive function to a symbiotic fungus. The ants feed their fungus - essentially an external digestive organ - a variety of substrates of botanical origin, including fresh and dried flowers, leaves and insect frass (processed leaves). Although plant tissues are rich in fibers (lignocelluloses, hemicelluloses, pectins and starches) and the symbiotic fungus possesses the genetic and enzymatic machinery to metabolize these compounds, the highly derived attines, the leaf-cutters (Atta and Acromyrmex), are known to produce fiber-rich waste. While leaf-cutting ants are important consumers of primary plant tissue, there have been fewer studies on physiological activity of fungi grown by closely related ant species in the genus Trachymyrmex, which generally grow related species of fungi, have smaller colonies and consume a wider variety of fungal substrates in addition to fresh leaves and flowers. In this study, we measured the cellulase activity of the fungus-gardening ants Atta texana, Trachymyrmex arizonensis and T. septentrionalis. We then quantified fiber consumption of the fungus-gardening ants Trachymyrmex septentrionalis and Trachymyrmex arizonensis by comparing the amounts and percentages present in their food and in fungus garden refuse during a controlled feeding experiment over the span of several months. Finally, we compared waste composition of T. arizonensis colonies growing different fungal strains, because this species is known to cultivate multiple strains of Leucoagaricus in its native range. The leaf-cutting ant A. texana was found to have lower cellulytic activity than T. arizonensis or T. septentrionalis. Total lignocellulose and hemicellulose amounts were significantly lower in refuse piles than in the substrates fed to the Trachymyrmex colonies, thus these fibers were consumed by the fungal symbionts of these ant species. Although lignocellulose utilization was similar in two distinct

  17. Unraveling Plant Responses to Bacterial Pathogens through Proteomics

    Directory of Open Access Journals (Sweden)

    Tamara Zimaro

    2011-01-01

    Full Text Available Plant pathogenic bacteria cause diseases in important crops and seriously and negatively impact agricultural production. Therefore, an understanding of the mechanisms by which plants resist bacterial infection at the stage of the basal immune response or mount a successful specific R-dependent defense response is crucial since a better understanding of the biochemical and cellular mechanisms underlying these interactions will enable molecular and transgenic approaches to crops with increased biotic resistance. In recent years, proteomics has been used to gain in-depth understanding of many aspects of the host defense against pathogens and has allowed monitoring differences in abundance of proteins as well as posttranscriptional and posttranslational processes, protein activation/inactivation, and turnover. Proteomics also offers a window to study protein trafficking and routes of communication between organelles. Here, we summarize and discuss current progress in proteomics of the basal and specific host defense responses elicited by bacterial pathogens.

  18. Unraveling plant responses to bacterial pathogens through proteomics

    KAUST Repository

    Zimaro, Tamara

    2011-11-03

    Plant pathogenic bacteria cause diseases in important crops and seriously and negatively impact agricultural production. Therefore, an understanding of the mechanisms by which plants resist bacterial infection at the stage of the basal immune response or mount a successful specific R-dependent defense response is crucial since a better understanding of the biochemical and cellular mechanisms underlying these interactions will enable molecular and transgenic approaches to crops with increased biotic resistance. In recent years, proteomics has been used to gain in-depth understanding of many aspects of the host defense against pathogens and has allowed monitoring differences in abundance of proteins as well as posttranscriptional and posttranslational processes, protein activation/inactivation, and turnover. Proteomics also offers a window to study protein trafficking and routes of communication between organelles. Here, we summarize and discuss current progress in proteomics of the basal and specific host defense responses elicited by bacterial pathogens. Copyright 2011 Tamara Zimaro et al.

  19. Avirulence proteins of plant pathogens: determinants of victory and defeat

    NARCIS (Netherlands)

    Luderer, R.; Joosten, M.H.A.J.

    2001-01-01

    The simplest way to explain the biochemical basis of the gene-for-gene concept is by direct interaction between a pathogen-derived avirulence (Avr) gene product and a receptor protein, which is encoded by the matching resistance (R) gene of the host plant. The number of R genes for which the

  20. The Top 10 fungal pathogens in molecular plant pathology

    NARCIS (Netherlands)

    Dean, R.; Kan, van J.A.L.; Pretorius, Z.A.; Hammond-Kosack, K.E.; Pietro, Di A.; Spanu, P.D.; Rudd, J.J.; Dickman, M.; Kahmann, R.; Ellis, J.; Foster, G.D.

    2012-01-01

    The aim of this review was to survey all fungal pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate which fungal pathogens they would place in a ‘Top 10’ based on scientific/economic importance. The survey generated 495 votes from the international co

  1. Splash : the dispersal of fungal plant pathogens in rain events

    NARCIS (Netherlands)

    Pielaat, A.

    2000-01-01

    Models were developed to study splash dispersal of fungal plant pathogens in space and time. The models incorporate the main mechanisms involved in splash dispersal, that is 1. A raindrop hits the thin water film on the crop surface containing spores and spores are dispersed in the splashing rain dr

  2. The Top 10 fungal pathogens in molecular plant pathology

    NARCIS (Netherlands)

    Dean, R.; Kan, van J.A.L.; Pretorius, Z.A.; Hammond-Kosack, K.E.; Pietro, Di A.; Spanu, P.D.; Rudd, J.J.; Dickman, M.; Kahmann, R.; Ellis, J.; Foster, G.D.

    2012-01-01

    The aim of this review was to survey all fungal pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate which fungal pathogens they would place in a ‘Top 10’ based on scientific/economic importance. The survey generated 495 votes from the international

  3. The Top 10 fungal pathogens in molecular plant pathology

    NARCIS (Netherlands)

    Dean, R.; Kan, van J.A.L.; Pretorius, Z.A.; Hammond-Kosack, K.E.; Pietro, Di A.; Spanu, P.D.; Rudd, J.J.; Dickman, M.; Kahmann, R.; Ellis, J.; Foster, G.D.

    2012-01-01

    The aim of this review was to survey all fungal pathologists with an association with the journal Molecular Plant Pathology and ask them to nominate which fungal pathogens they would place in a ‘Top 10’ based on scientific/economic importance. The survey generated 495 votes from the international co

  4. Microbial populations responsible for specific soil suppressiveness to plant pathogens

    NARCIS (Netherlands)

    Weller, D.M.; Raaijmakers, J.M.; McSpadden Gardener, B.B.; Thomashow, L.S.

    2002-01-01

    Agricultural soils suppressive to soilborne plant pathogens occur worldwide, and for several of these soils the biological basis of suppressiveness has been described. Two classical types of suppressiveness are known. General suppression owes its activity to the total microbial biomass in soil and i

  5. Improving ITS sequence data for identification of plant pathogenic fungi

    Science.gov (United States)

    R. Henrik Nilsson; Kevin D. Hyde; Julia Pawłowska; Martin Ryberg; Leho Tedersoo; Anders Bjørnsgard Aas; Siti A. Alias; Artur Alves; Cajsa Lisa Anderson; Alexandre Antonelli; A. Elizabeth Arnold; Barbara Bahnmann; Mohammad Bahram; Johan Bengtsson-Palme; Anna Berlin; Sara Branco; Putarak Chomnunti; Asha Dissanayake; Rein Drenkhan; Hanna Friberg; Tobias Guldberg Frøslev; Bettina Halwachs; Martin Hartmann; Beatrice Henricot; Ruvishika Jayawardena; Ari Jumpponen; Håvard Kauserud; Sonja Koskela; Tomasz Kulik; Kare Liimatainen; Björn D. Lindahl; Daniel Lindner; Jian-Kui Liu; Sajeewa Maharachchikumbura; Dimuthu Manamgoda; Svante Martinsson; Maria Alice Neves; Tuula Niskanen; Stephan Nylinder; Olinto Liparini Pereira; Danilo Batista Pinho; Teresita M. Porter; Valentin Queloz; Taavi Riit; Marisol Sánchez-García; Filipe de Sousa; Emil Stefańczyk; Mariusz Tadych; Susumu Takamatsu; Qing Tian; Dhanushka Udayanga; Martin Unterseher; Zheng Wang; Saowanee Wikee; Jiye Yan; Ellen Larsson; Karl-Henrik Larsson; Urmas Kõljalg; Kessy Abarenkov

    2014-01-01

    Plant pathogenic fungi are a large and diverse assemblage of eukaryotes with substantial impacts on natural ecosystems and human endeavours. These taxa often have complex and poorly understood life cycles, lack observable, discriminatory morphological characters, and may not be amenable to in vitro culturing. As a result, species identification is frequently difficult...

  6. Antibiosis of Trichoderma spp strains native to northeastern Mexico against the pathogenic fungus Macrophomina phaseolina.

    Science.gov (United States)

    Mendoza, José Luis Hernández; Pérez, María Isabel Sánchez; Prieto, Juan Manuel González; Velásquez, Jesús DiCarlo Quiroz; Olivares, Jesús Gerardo García; Langarica, Homar Rene Gill

    2015-01-01

    Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS) 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen.

  7. Antibiosis of Trichoderma spp strains native to northeastern Mexico against the pathogenic fungus Macrophomina phaseolina

    Science.gov (United States)

    Mendoza, José Luis Hernández; Pérez, María Isabel Sánchez; Prieto, Juan Manuel González; Velásquez, Jesús DiCarlo Quiroz; Olivares, Jesús Gerardo García; Langarica, Homar Rene Gill

    2015-01-01

    Abstract Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS) 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen. PMID:26691467

  8. Antibiosis of Trichoderma spp strains native to northeastern Mexico against the pathogenic fungus Macrophomina phaseolina

    Directory of Open Access Journals (Sweden)

    José Luis Hernández Mendoza

    2015-12-01

    Full Text Available Abstract Sampling of agricultural soils from the Mexican northeastern region was performed to detect Trichoderma spp., genetically characterize it, and assess its potential use as a biologic control agent against Macrophomina phaseolina. M. phaseolina is a phytopathogen that attacks over 500 species of cultivated plants and causes heavy losses in the regional sorghum crop. Sampling was performed immediately after sorghum or corn harvest in an area that was approximately 170 km from the Mexico-USA border. Sixteen isolates were obtained in total. Using colony morphology and sequencing the internal transcribed spacers (ITS 1 and 4 of 18S rDNA, 14 strains were identified as Trichoderma harzianum, T. koningiopsis and T. virens. Subsequently, their antagonistic activity against M. phaseolina was evaluated in vitro, and 11 isolates showed antagonism by competition and stopped M. phaseolina growth. In 4 of these isolates, the antibiosis phenomenon was observed through the formation of an intermediate band without growth between colonies. One strain, HTE808, was identified as Trichoderma koningiopsis and grew rapidly; when it came into contact with the M. phaseolina colony, it continued to grow and sporulated until it covered the entire petri dish. Microscopic examination confirmed that it has a high level of hyperparasitism and is thus considered to have high potential for use in the control of this phytopathogen.

  9. Interaction between TATA-Binding Protein (TBP and Multiprotein Bridging Factor-1 (MBF1 from the Filamentous Insect Pathogenic Fungus Beauveria bassiana.

    Directory of Open Access Journals (Sweden)

    Chi Song

    Full Text Available TATA-binding protein (TBP is a ubiquitous component of eukaryotic transcription factors that acts to nucleate assembly and position pre-initiation complexes. Multiprotein bridging factor 1 (MBF1 is thought to interconnect TBP with gene specific transcriptional activators, modulating transcriptional networks in response to specific signal and developmental programs. The insect pathogen, Beauveria bassiana, is a cosmopolitan fungus found in most ecosystems where it acts as an important regulator of insect populations and can form intimate associations with certain plants. In order to gain a better understanding of the function of MBF1 in filamentous fungi, its interaction with TBP was demonstrated. The MBF1 and TBP homologs in B. bassiana were cloned and purified from a heterologous E. coli expression system. Whereas purified BbTBP was shown to be able to bind oligonucleotide sequences containing the TATA-motif (Kd ≈ 1.3 nM including sequences derived from the promoters of the B. bassiana chitinase and protease genes. In contrast, BbMBF1 was unable to bind to these same target sequences. However, the formation of a ternary complex between BbMBF1, BbTBP, and a TATA-containing target DNA sequence was seen in agarose gel electrophoretic mobility shift assays (EMSA. These data indicate that BbMBF1 forms direct interactions with BbTBP, and that the complex is capable of binding to DNA sequences containing TATA-motifs, confirming that BbTBP can link BbMBF1 to target sequences as part of the RNA transcriptional machinery in fungi.

  10. Antibacterial activity of caffeine against plant pathogenic bacteria.

    Science.gov (United States)

    Sledz, Wojciech; Los, Emilia; Paczek, Agnieszka; Rischka, Jacek; Motyka, Agata; Zoledowska, Sabina; Piosik, Jacek; Lojkowska, Ewa

    2015-01-01

    The objective of the present study was to evaluate the antibacterial properties of a plant secondary metabolite - caffeine. Caffeine is present in over 100 plant species. Antibacterial activity of caffeine was examined against the following plant-pathogenic bacteria: Ralstonia solanacearum (Rsol), Clavibacter michiganesis subsp. sepedonicus (Cms), Dickeya solani (Dsol), Pectobacterium atrosepticum (Pba), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pseudomonas syringae pv. tomato (Pst), and Xanthomonas campestris subsp. campestris (Xcc). MIC and MBC values ranged from 5 to 20 mM and from 43 to 100 mM, respectively. Caffeine increased the bacterial generation time of all tested species and caused changes in cell morphology. The influence of caffeine on the synthesis of DNA, RNA and proteins was investigated in cultures of plant pathogenic bacteria with labelled precursors: [(3)H]thymidine, [(3)H]uridine or (14)C leucine, respectively. RNA biosynthesis was more affected than DNA or protein biosynthesis in bacterial cells treated with caffeine. Treatment of Pba with caffeine for 336 h did not induce resistance to this compound. Caffeine application reduced disease symptoms caused by Dsol on chicory leaves, potato slices, and whole potato tubers. The data presented indicate caffeine as a potential tool for the control of diseases caused by plant-pathogenic bacteria, especially under storage conditions.

  11. Solubilization of phosphates and micronutrients by the plant-growth-promoting and biocontrol fungus trichoderma harzianum rifai 1295-22

    Science.gov (United States)

    Altomare; Norvell; Bjorkman; Harman

    1999-07-01

    We investigated the capability of the plant-growth-promoting and biocontrol fungus Trichoderma harzianum Rifai 1295-22 (T-22) to solubilize in vitro some insoluble or sparingly soluble minerals via three possible mechanisms: acidification of the medium, production of chelating metabolites, and redox activity. T-22 was able to solubilize MnO2, metallic zinc, and rock phosphate (mostly calcium phosphate) in a liquid sucrose-yeast extract medium, as determined by inductively coupled plasma emission spectroscopy. Acidification was not the major mechanism of solubilization since the pH of cultures never fell below 5.0 and in cultures containing MnO2 the pH rose from 6.8 to 7.4. Organic acids were not detected by high-performance thin-layer chromatography in the culture filtrates. Fe2O3, MnO2, Zn, and rock phosphate were also solubilized by cell-free culture filtrates. The chelating activity of T-22 culture filtrates was determined by a method based on measurement of the equilibrium concentration of the chrome azurol S complex in the presence of other chelating substances. A size exclusion chromatographic separation of the components of the culture filtrates indicated the presence of a complexed form of Fe but no chelation of Mn. In liquid culture, T. harzianum T-22 also produced diffusible metabolites capable of reducing Fe(III) and Cu(II), as determined by the formation of Fe(II)-Na2-bathophenanthrolinedisulfonic acid and Cu(I)-Na2-2, 9-dimethyl-4,7-diphenyl-1,10-phenanthrolinedisulfonic acid complexes. This is the first report of the ability of a Trichoderma strain to solubilize insoluble or sparingly soluble minerals. This activity may explain, at least partially, the ability of T-22 to increase plant growth. Solubilization of metal oxides by Trichoderma involves both chelation and reduction. Both of these mechanisms also play a role in biocontrol of plant pathogens, and they may be part of a multiple-component action exerted by T-22 to achieve effective biocontrol

  12. The effect of elevated atmospheric CO{sub 2} on interactions between plant roots, arbuscular-mycorrhizal and pathogenic fungi

    Energy Technology Data Exchange (ETDEWEB)

    Rillig, M.C.; Klironomos, J.N.; Allen, M.F. [San Diego State Univ., CA (United States)] [and others

    1995-09-01

    Of all effects of elevated atmospheric CO{sub 2} on plants and ecosystems, the least is known about plant rhizosphere responses. Rhizosphere fungi are fed primarily by root-derived substrates, and fulfill functions such as immobilization, decomposition, pathogeneity, and improvement of plant nutrition. This study describes the effect of elevated CO{sub 2} on the interaction between the pathogen Fusarium solani and the AM fungus Glomus intraradices in the rhizosphere of Artemisia tridentata. We measured intraradical infection and extraradical growth by the two fungi under elevated and ambient CO{sub 2} concentrations. We found a strong interaction between the two fungi. Root infection by and extraradical hyphal length of solani did not differ significantly between CO{sub 2} treatments in the presence of G. intraradices. In the absence of G. intraradices, however, infection by F. solani and its extraradical hyphal length increased under elevated CO{sub 2}. Our results indicate that pathogenic fungi do respond to elevated CO{sub 2} by increased hyphal growth and root infection (potential response), but also show that mycorrhizal fungi can profit more from the new conditions and serve to suppress the pathogen.

  13. Crossover fungal pathogens: the biology and pathogenesis of fungi capable of crossing kingdoms to infect plants and humans.

    Science.gov (United States)

    Gauthier, Gregory M; Keller, Nancy P

    2013-12-01

    The outbreak of fungal meningitis associated with contaminated methylprednisolone acetate has thrust the importance of fungal infections into the public consciousness. The predominant pathogen isolated from clinical specimens, Exserohilum rostratum (teleomorph: Setosphaeria rostrata), is a dematiaceous fungus that infects grasses and rarely humans. This outbreak highlights the potential for fungal pathogens to infect both plants and humans. Most crossover or trans-kingdom pathogens are soil saprophytes and include fungi in Ascomycota and Mucormycotina phyla. To establish infection, crossover fungi must overcome disparate, host-specific barriers, including protective surfaces (e.g. cuticle, skin), elevated temperature, and immune defenses. This review illuminates the underlying mechanisms used by crossover fungi to cause infection in plants and mammals, and highlights critical events that lead to human infection by these pathogens. Several genes including veA, laeA, and hapX are important in regulating biological processes in fungi important for both invasive plant and animal infections. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Plant pathogens but not antagonists change in soil fungal communities across a land abandonment gradient in a Mediterranean landscape

    Science.gov (United States)

    Bosso, L.; Lacatena, F.; Varlese, R.; Nocerino, S.; Cristinzio, G.; Russo, D.

    2017-01-01

    We assessed whether the presence and abundance of plant pathogens and antagonists change in soil fungal communities along a land abandonment gradient. The study was carried out in the Cilento area (Southern Italy) at a site with three different habitats found along a land abandonment gradient: agricultural land, Mediterranean shrubland and woodland. For all microbiological substrates the colony forming units were about 3.1 × 106 g-1 soil for agricultural land and about 1.1 × 106 g-1 soil for Mediterranean shrubland and woodland. We found the following genera in all habitats: Cladosporium, Mortierella, Penicillium and Trichoderma. In agricultural land, the significantly most abundant fungus genera were Aspergillus, Fusarium, Cylindrocarpon and Nectria; in Mediterranean shrubland, Rhizopus and Trichoderma; and in woodland, Bionectria, Mortierella, Cladosporium, Diplodia, Paecilomyces, Penicillium and Trichoderma. We found a total of 8, 8 and 9 species of fungal antagonist, and 16, 6 and 6 species of fungal plant pathogens in agricultural land, Mediterranean shrubland and woodland respectively. Fungal plant pathogens decreased significantly over a land abandonment gradient, while we no found significant differences among fungal antagonists in the three habitats. We conclude that a decrease in the number of fungal pathogen species occurs when formerly cultivated areas are abandoned. On the other hand, fungal antagonists seem not to be affected by this process.

  15. Plant growth-promotion (PGP) activities and molecular characterization of rhizobacterial strains isolated from soybean (Glycine max L. Merril) plants against charcoal rot pathogen, Macrophomina phaseolina.

    Science.gov (United States)

    Choudhary, D K

    2011-11-01

    Charcoal rot disease, caused by the fungus Macrophomina phaseolina, leads to significant yield losses of soybean crops. One strategy to control charcoal rot is the use of antagonistic, root-colonizing bacteria. Rhizobacteria A(5)F and FPT(7)21 and Pseudomonas sp. strain GRP(3) were characterized for their plant growth-promotion activities against the pathogen. Rhizobacterium FPT(7)21 exhibited higher antagonistic activity against the pathogen on dual plate assay compared to strain A(5)F and GRP(3). FPT(7)21 and GRP(3) gave decreased disease intensity in terms of average number of pathogen-infested plants. Lipoxygenase (LOX), phenylalanine ammonia-lyase (PAL), and peroxidase (POD) activities were estimated in extracts of plants grown from seeds that were treated with rhizobacteria, and inoculated with spore suspension of M. phaseolina. The activity of these enzymes after challenge with the test pathogen increased. Strains FPT(7)21 and GRP(3) exhibited maximum increases in LOX, PAL and POD activity (U mg(-1) fresh leaf wt) compared to strain A(5)F.

  16. Compatibility of the insect pathogenic fungus Beauveria bassiana with neem against sweetpotato whitefly, Bemisia tabaci, on eggplant

    Science.gov (United States)

    A study on the compatibility of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) with neem was conducted against sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), on eggplant. Initially, three concentrations of B. bassiana (106, 1...

  17. Development of a greenhouse-based inoculation protocol for the fungus Colletotrichum cereale pathogenic to annual bluegrass (Poa annua)

    Science.gov (United States)

    The fungus Colletotrichum cereale incites anthracnose disease on Poa annua (annual bluegrass) turfgrass. Anthracnose disease is geographically widespread highly destructive, with infections by C. cereale resulting in extensive turfgrass loss. Comprehensive research aimed at controlling turfgrass a...

  18. New Meroterpenoids from the Endophytic Fungus Aspergillus flavipes AIL8 Derived from the Mangrove Plant Acanthus ilicifolius

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Bai

    2015-01-01

    Full Text Available Four new meroterpenoids (2–5, along with three known analogues (1, 6, and 7 were isolated from mangrove plant Acanthus ilicifolius derived endophytic fungus Aspergillus flavipes. The structures of these compounds were elucidated by NMR and MS analysis, the configurations were assigned by CD data, and the stereochemistry of 1 was confirmed by X-ray crystallography analysis. A possible biogenetic pathway of compounds 1–7 was also proposed. All compounds were evaluated for antibacterial and cytotoxic activities.

  19. Innovative tools for detection of plant pathogenic viruses and bacteria.

    Science.gov (United States)

    López, María M; Bertolini, Edson; Olmos, Antonio; Caruso, Paola; Gorris, María Teresa; Llop, Pablo; Penyalver, Ramón; Cambra, Mariano

    2003-12-01

    Detection of harmful viruses and bacteria in plant material, vectors or natural reservoirs is essential to ensure safe and sustainable agriculture. The techniques available have evolved significantly in the last few years to achieve rapid and reliable detection of pathogens, extraction of the target from the sample being important for optimising detection. For viruses, sample preparation has been simplified by imprinting or squashing plant material or insect vectors onto membranes. To improve the sensitivity of techniques for bacterial detection, a prior enrichment step in liquid or solid medium is advised. Serological and molecular techniques are currently the most appropriate when high numbers of samples need to be analysed. Specific monoclonal and/or recombinant antibodies are available for many plant pathogens and have contributed to the specificity of serological detection. Molecular detection can be optimised through the automatic purification of nucleic acids from pathogens by columns or robotics. New variants of PCR, such as simple or multiplex nested PCR in a single closed tube, co-operative-PCR and real-time monitoring of amplicons or quantitative PCR, allow high sensitivity in the detection of one or several pathogens in a single assay. The latest development in the analysis of nucleic acids is micro-array technology, but it requires generic DNA/RNA extraction and pre-amplification methods to increase detection sensitivity. The advances in research that will result from the sequencing of many plant pathogen genomes, especially now in the era of proteomics, represent a new source of information for the future development of sensitive and specific detection techniques for these microorganisms.

  20. BIOLOGICAL CONTROL OF WEEDS BY MEANS OF PLANT PATHOGENS

    Directory of Open Access Journals (Sweden)

    Marija Ravlić

    2014-06-01

    Full Text Available Biological control is the use of live beneficial organisms and products of their metabolism in the pests control. Plant pathogens can be used for weed control in three different ways: as classical, conservation and augmentative (inoculative and inundated biological control. Inundated biological control involves the use of bioherbicides (mycoherbicides or artificial breeding of pathogens and application in specific stages of crops and weeds. Biological control of weeds can be used where chemical herbicides are not allowed, if resistant weed species are present or in the integrated pest management against weeds with reduced herbicides doses and other non-chemical measures, but it has certain limitations and disadvantages.

  1. Cytochrome b gene structure and consequences for resistance to Qo inhibitor fungicides in plant pathogens.

    Science.gov (United States)

    Grasso, Valeria; Palermo, Simona; Sierotzki, Helge; Garibaldi, Angelo; Gisi, Ulrich

    2006-06-01

    The cytochrome b (cyt b) gene structure was characterized for different agronomically important plant pathogens, such as Puccinia recondita f sp tritici (Erikss) CO Johnston, P graminis f sp tritici Erikss and Hennings, P striiformis f sp tritici Erikss, P coronata f sp avenae P Syd & Syd, P hordei GH Otth, P recondita f sp secalis Roberge, P sorghi Schwein, P horiana Henn, Uromyces appendiculatus (Pers) Unger, Phakopsora pachyrhizi Syd & P Syd, Hemileia vastatrix Berk & Broome, Alternaria solani Sorauer, A alternata (Fr) Keissl and Plasmopara viticola (Berk & Curt) Berlese & de Toni. The sequenced fragment included the two hot spot regions in which mutations conferring resistance to QoI fungicides may occur. The cyt b gene structure of these pathogens was compared with that of other species from public databases, including the strobilurin-producing fungus Mycena galopoda (Pers) P Kumm, Saccharomyces cerevisiae Meyer ex Hansen, Venturia inaequalis (Cooke) Winter and Mycosphaerella fijiensis Morelet. In all rust species, as well as in A solani, resistance to QoI fungicides caused by the mutation G143A has never been reported. A type I intron was observed directly after the codon for glycine at position 143 in these species. This intron was absent in pathogens such as A alternata, Blumeria graminis (DC) Speer, Pyricularia grisea Sacc, Mycosphaerella graminicola (Fuckel) J Schröt, M fijiensis, V inaequalis and P viticola, in which resistance to QoI fungicides has occurred and the glycine is replaced by alanine at position 143 in the resistant genotype. The present authors predict that a nucleotide substitution in codon 143 would prevent splicing of the intron, leading to a deficient cytochrome b, which is lethal. As a consequence, the evolution of resistance to QoI fungicides based on G143A is not likely to evolve in pathogens carrying an intron directly after this codon.

  2. Molecular Keys to the Janthinobacterium and Duganella spp. Interaction with the Plant Pathogen Fusarium graminearum

    Directory of Open Access Journals (Sweden)

    Frederike S. Haack

    2016-10-01

    Full Text Available Janthinobacterium and Duganella are well-known for their antifungal effects. Surprisingly, almost nothing is known on molecular aspects involved in the close bacterium-fungus interaction. To better understand this interaction, we established the genomes of eleven Janthinobacterium and Duganella isolates in combination with phylogenetic and functional analyses of all publicly available genomes. Thereby, we identified a core and pan genome of 1,058 and 23,628 genes. All strains encoded secondary metabolite gene clusters and chitinases, both possibly involved in fungal growth suppression. All but one strain carried a single gene cluster involved in the biosynthesis of alpha-hydroxyketone-like autoinducer molecules, designated JAI-1. Genome wide RNA-seq studies employing the background of two isolates and the corresponding JAI-1 deficient strains identified a set of 45 QS-regulated genes in both isolates. Most regulated genes are characterized by a conserved sequence motif within the promoter region. Among the most strongly regulated genes were secondary metabolite and type VI secretion system gene clusters. Most intriguing, co-incubation studies of J. sp. HH102 or its corresponding JAI-1 synthase deletion mutant with the plant pathogen Fusarium graminearum provided first evidence of a QS-dependent interaction with this pathogen.

  3. Pseudogenization in pathogenic fungi with different host plants and lifestyles might reflect their evolutionary past.

    Science.gov (United States)

    van der Burgt, Ate; Karimi Jashni, Mansoor; Bahkali, Ali H; de Wit, Pierre J G M

    2014-02-01

    Pseudogenes are genes with significant homology to functional genes, but contain disruptive mutations (DMs) leading to the production of non- or partially functional proteins. Little is known about pseudogenization in pathogenic fungi with different lifestyles. Here, we report the identification of DMs causing pseudogenes in the genomes of the fungal plant pathogens Botrytis cinerea, Cladosporium fulvum, Dothistroma septosporum, Mycosphaerella fijiensis, Verticillium dahliae and Zymoseptoria tritici. In these fungi, we identified 1740 gene models containing 2795 DMs obtained by an alignment-based gene prediction method. The contribution of sequencing errors to DMs was minimized by analyses of resequenced genomes to obtain a refined dataset of 924 gene models containing 1666 true DMs. The frequency of pseudogenes varied from 1% to 5% in the gene catalogues of these fungi, being the highest in the asexually reproducing fungus C. fulvum (4.9%), followed by D. septosporum (2.4%) and V. dahliae (2.1%). The majority of pseudogenes do not represent recent gene duplications, but members of multi-gene families and unitary genes. In general, there was no bias for pseudogenization of specific genes in the six fungi. Single exceptions were those encoding secreted proteins, including proteases, which appeared more frequently pseudogenized in C. fulvum than in D. septosporum. Most pseudogenes present in these two phylogenetically closely related fungi are not shared, suggesting that they are related to adaptation to a different host (tomato versus pine) and lifestyle (biotroph versus hemibiotroph). © 2013 BSPP AND JOHN WILEY & SONS LTD.

  4. 3-Methylthiopropionic Acid of Rhizoctonia solani AG-3 and Its Role in the Pathogenicity of the Fungus

    Directory of Open Access Journals (Sweden)

    Frederick Kankam

    2016-04-01

    Full Text Available Studies were conducted to determine the role of 3-methylthioproprionic acid (MTPA in the pathogenicity of potato stem canker, Rhizoctonia solani, and the concentrations required to inhibit growth of R. solani under laboratory and plant house-based conditions. The experiments were laid out in a completely randomized design with five treatments and five replications. The treatments were 0, 1, 2, 4, and 8 mM concentrations of MTPA. The purified toxin exhibited maximal activity at pH 2.5 and 30°C. MTPA at 1, 2, 4, and 8 mM levels reduced plant height, chlorophyll content, haulm fresh weight, number of stolons, canopy development, and tuber weight of potato plants, as compared to the control. MTPA significantly affected mycelial growth with 8 mM causing the highest infection. The potato seedlings treated with MTPA concentrations of 1.0–8.0 mM induced necrosis of up to 80% of root system area. Cankers were resulted from the injection of potato seedling stems with 8.0 mM MTPA. The results showed the disappearance of cell membrane, rough mitochondrial and cell walls, change of the shape of chloroplasts, and swollen endoplasmic reticulum. Seventy-six (76 hours after toxin treatment, cell contents were completely broken, cytoplasm dissolved, and more chromatin were seen in the nucleus. The results suggested that high levels of the toxin concentration caused cell membrane and cytoplasm fracture. The integrity of cellular structure was destroyed by the phytotoxin. The concentrations of the phytotoxin were significantly correlated with pathogenicity and caused damage to the cell membrane of potato stem base tissue.

  5. Salmonella, a cross-kingdom pathogen infecting humans and plants.

    Science.gov (United States)

    Hernández-Reyes, Casandra; Schikora, Adam

    2013-06-01

    Infections with non-typhoidal Salmonella strains are constant and are a non-negligible threat to the human population. In the last two decades, salmonellosis outbreaks have increasingly been associated with infected fruits and vegetables. For a long time, Salmonellae were assumed to survive on plants after a more or less accidental infection. However, this notion has recently been challenged. Studies on the infection mechanism in vegetal hosts, as well as on plant immune systems, revealed an active infection process resembling in certain features the infection in animals. On one hand, Salmonella requires the type III secretion systems to effectively infect plants and to suppress their resistance mechanisms. On the other hand, plants recognize these bacteria and react to the infection with an induced defense mechanism similar to the reaction to other plant pathogens. In this review, we present the newest reports on the interaction between Salmonellae and plants. We discuss the possible ways used by these bacteria to infect plants as well as the plant responses to the infection. The recent findings indicate that plants play a central role in the dissemination of Salmonella within the ecosystem.

  6. Pathogen and biological contamination management in plant tissue culture: phytopathogens, vitro pathogens, and vitro pests.

    Science.gov (United States)

    Cassells, Alan C

    2012-01-01

    The ability to establish and grow plant cell, organ, and tissue cultures has been widely exploited for basic and applied research, and for the commercial production of plants (micro-propagation). Regardless of whether the application is for research or commerce, it is essential that the cultures be established in vitro free of biological contamination and be maintained as aseptic cultures during manipulation, growth, and storage. The risks from microbial contamination are spurious experimental results due to the effects of latent contaminants or losses of valuable experimental or commercial cultures. Much of the emphasis in culture contamination management historically focussed on the elimination of phytopathogens and the maintenance of cultures free from laboratory contamination by environmental bacteria, fungi (collectively referred to as "vitro pathogens", i.e. pathogens or environmental micro-organisms which cause culture losses), and micro-arthropods ("vitro pests"). Microbial contamination of plant tissue cultures is due to the high nutrient availability in the almost universally used Murashige and Skoog (Physiol Plant 15:473-497, 1962) basal medium or variants of it. In recent years, it has been shown that many plants, especially perennials, are at least locally endophytically colonized intercellularly by bacteria. The latter, and intracellular pathogenic bacteria and viruses/viroids, may pass latently into culture and be spread horizontally and vertically in cultures. Growth of some potentially cultivable endophytes may be suppressed by the high salt and sugar content of the Murashige and Skoog basal medium and suboptimal temperatures for their growth in plant tissue growth rooms. The management of contamination in tissue culture involves three stages: disease screening (syn. disease indexing) of the stock plants with disease and endophyte elimination where detected; establishment and pathogen and contaminant screening of established initial cultures

  7. Pathogenic infection and the oxidative defences in plant apoplast.

    Science.gov (United States)

    Bolwell, P P; Page, A; Piślewska, M; Wojtaszek, P

    2001-01-01

    The structural and functional continuum of the plant apoplast is the first site of contact with a pathogen and plays a crucial role in initiation and coordination of many defence responses. In this paper, we present an overview of the involvement of the plant apoplast in plant-pathogen interactions. The process of infection of French bean (Phaseolus vulgaris L.) plants by Colletotrichum lindemuthianum is analysed. The ultrastructural features of plant defence responses to fungal infection are then compared with those observed in plants or cell suspensions treated with various elicitors. Changes in cell walls and in whole plant cells responding to infection seem to be highly similar in all systems used. Model systems of French bean and white lupin (Lupinus albus L.) are then utilised to provide some biochemical characteristics of oxidative reactions in the apoplast evoked by elicitor treatment. The species specificity of various mechanisms generating reactive oxygen species is discussed, and some details of pH-dependent H2O2-generating activity of peroxidases are demonstrated. As its exocellular nature is an important feature of the oxidative burst, the major consequence of this event, i.e., the oxidative cross-linking of wall components during the papilla formation and strengthening of the walls, is analysed. Finally, the possible involvement of other wall-associated and developmentally regulated H2O2-generating mechanisms, like amine and oxalate oxidases, in plant defence is demonstrated. It is concluded that under stress conditions, such apoplastic mechanisms might be employed to increase plants' chances of survival.

  8. Lifestyles of the effector-rich: genome-enabled characterization of bacterial plant pathogens

    Science.gov (United States)

    Genome sequencing of bacterial plant pathogens is providing transformative insights into the complex network of molecular plant-microbe interactions mediated by extracellular effectors during pathogenesis. Bacterial pathogens sequenced to completion are phylogenetically diverse and vary significant...

  9. The Brucella suis Genome Reveals Fundamental Similarities between Animal and Plant Pathogens and Symbionts

    National Research Council Canada - National Science Library

    Ian T. Paulsen; Rekha Seshadri; Karen E. Nelson; Jonathan A. Eisen; John F. Heidelberg; Timothy D. Read; Robert J. Dodson; Lowell Umayam; Lauren M. Brinkac; Maureen J. Beanan; Sean C. Daugherty; Robert T. Deboy; A. Scott Durkin; James F. Kolonay; Ramana Madupu; William C. Nelson; Bola Ayodeji; Margaret Kraul; Jyoti Shetty; Joel Malek; Susan E. van Aken; Steven Riedmuller; Herve Tettelin; Steven R. Gill; Owen White; Steven L. Salzberg; David L. Hoover; Luther E. Lindler; Shirley M. Halling; Stephen M. Boyle; Claire M. Fraser

    2002-01-01

    .... Extensive gene synteny between B. suis chromosome 1 and the genome of the plant symbiont Mesorhizobium loti emphasizes the similarity between this animal pathogen and plant pathogens and symbionts...

  10. Plant-pathogen interactions: what microarray tells about it?

    Science.gov (United States)

    Lodha, T D; Basak, J

    2012-01-01

    Plant defense responses are mediated by elementary regulatory proteins that affect expression of thousands of genes. Over the last decade, microarray technology has played a key role in deciphering the underlying networks of gene regulation in plants that lead to a wide variety of defence responses. Microarray is an important tool to quantify and profile the expression of thousands of genes simultaneously, with two main aims: (1) gene discovery and (2) global expression profiling. Several microarray technologies are currently in use; most include a glass slide platform with spotted cDNA or oligonucleotides. Till date, microarray technology has been used in the identification of regulatory genes, end-point defence genes, to understand the signal transduction processes underlying disease resistance and its intimate links to other physiological pathways. Microarray technology can be used for in-depth, simultaneous profiling of host/pathogen genes as the disease progresses from infection to resistance/susceptibility at different developmental stages of the host, which can be done in different environments, for clearer understanding of the processes involved. A thorough knowledge of plant disease resistance using successful combination of microarray and other high throughput techniques, as well as biochemical, genetic, and cell biological experiments is needed for practical application to secure and stabilize yield of many crop plants. This review starts with a brief introduction to microarray technology, followed by the basics of plant-pathogen interaction, the use of DNA microarrays over the last decade to unravel the mysteries of plant-pathogen interaction, and ends with the future prospects of this technology.

  11. Effects of alkyl parabens on plant pathogenic fungi.

    Science.gov (United States)

    Ito, Shinsaku; Yazawa, Satoru; Nakagawa, Yasutaka; Sasaki, Yasuyuki; Yajima, Shunsuke

    2015-04-15

    Alkyl parabens are used as antimicrobial preservatives in cosmetics, food, and pharmaceutical products. However, the mode of action of these chemicals has not been assessed thoroughly. In this study, we determined the effects of alkyl parabens on plant pathogenic fungi. All the fungi tested, were susceptible to parabens. The effect of linear alkyl parabens on plant pathogenic fungi was related to the length of the alkyl chain. In addition, the antifungal activity was correlated with the paraben-induced inhibition of oxygen consumption. The antifungal activity of linear alkyl parabens likely originates, at least in part, from their ability to inhibit the membrane respiratory chain, especially mitochondrial complex II. Additionally, we determined that some alkyl parabens inhibit Alternaria brassicicola infection of cabbage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Botryosphaeria dothidea: a latent pathogen of global importance to woody plant health.

    Science.gov (United States)

    Marsberg, Angelica; Kemler, Martin; Jami, Fahimeh; Nagel, Jan H; Postma-Smidt, Alisa; Naidoo, Sanushka; Wingfield, Michael J; Crous, Pedro W; Spatafora, Joseph W; Hesse, Cedar N; Robbertse, Barbara; Slippers, Bernard

    2017-05-01

    Botryosphaeria dothidea is the type species of Botryosphaeria (Botryosphaeriaceae, Botryosphaeriales). Fungi residing in this order are amongst the most widespread and important canker and dieback pathogens of trees worldwide, with B. dothidea one of the most common species on a large number of hosts. Its taxonomic circumscription has undergone substantial change in the past decade, making it difficult to interpret the large volume of literature linked to the name B. dothidea. This pathogen profile synthesizes the current understanding of B. dothidea pertaining to its distribution, host associations and role as a pathogen in managed and natural woody environments. The prolonged latent infection or endophytic phase is of particular importance, as it implies that the fungus can easily pass undetected by quarantine systems in traded living plants, fruits and other plant parts. Infections typically become obvious only under conditions of host stress, when disease symptoms develop. This study also considers the knowledge emerging from the recently sequenced B. dothidea genome, elucidating previously unknown aspects of the species, including mating and host infection strategies. Despite more than 150 years of research on B. dothidea, there is clearly much to be learned regarding this global tree pathogen. This is increasingly important given the stresses imposed on various woody hosts as a result of climate change. Botryosphaeria dothidea (Moug. ex Fr) Ces. & De Not, 1863. Kingdom Fungi, Phylum Ascomycota, Class Dothideomycetes, Order Botryosphaeriales, Family Botryosphaeriaceae, Genus Botryosphaeria, Species dothidea. Confirmed on more than 24 host genera, including woody plants, such as Acacia (= Vachellia), Eucalyptus, Vitis and Pistachio. Associated with twig, branch and stem cankers, tip and branch dieback, fruit rot, blue stain and plant death. The Botryosphaeria site for detailed morphological descriptions (http

  13. The pathogenicity of Beauveria bassiana: what happens after an endophytic phase in plants?

    Science.gov (United States)

    Akello, J; Dubois, T; Coyne, D; Kyamanywa, S

    2010-01-01

    The banana weevil Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) is a serious constraint to banana (Musa spp.) production throughout the world. The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) offers a potential weevil management option, but conventional delivery mechanisms have limited its success. As an endophyte, however, B. bassiana can be efficiently delivered to banana planting materials for the potential management of C. sordidus. However, entomopathogens can change morphology and efficacy against their target host when successively sub-cultured on artificial media or when exposed to certain physical and chemical environmental conditions. Whether such changes occur in B. bassiana after an endophytic phase inside a banana plant remains unknown. The primary aim of our study was to evaluate the viability, growth, sporulation and pathogenicity of endophytic B. bassiana. To attain this, two sets of experiments, namely morphological characterization and larval bioassays, were conducted under laboratory conditions. In these experiments, growth and pathogenicity of the wild-type B. bassiana strain G41, obtained originally from banana farms, was compared with the endophytic B. bassiana strain G41, re-isolated from the rhizome of B. bassiana-inoculated banana plants at one month post-inoculation. Morphological characterization, conidial germination, colony growth and sporulation rate was assessed on SDAY media while pathogenicity was determined 15 days after immersing the larvae of C. sordidus in different conidial doses. No differences were observed in colony appearance and growth rate between the endophytic and wild-type strain. Percentage conidial germination for the endophytic strain (91.4-94.0%) was higher than for the wild-type (86.6-89.7%). LD50 equated 1.76 x 10(5) and 0.71 x 10(5) conidia/ml for the wild-type and endophytic B. bassiana strains, respectively, but did not differ between strains. Our study

  14. Characterization of PbPga1, an antigenic GPI-protein in the pathogenic fungus Paracoccidioides brasiliensis.

    Directory of Open Access Journals (Sweden)

    Clarissa X R Valim

    Full Text Available Paracoccidioides brasiliensis is the etiologic agent of paracoccidioidomycosis (PCM, one of the most prevalent mycosis in Latin America. P. brasiliensis cell wall components interact with host cells and influence the pathogenesis of PCM. Cell wall components, such as glycosylphosphatidylinositol (GPI-proteins play a critical role in cell adhesion and host tissue invasion. Although the importance of GPI-proteins in the pathogenesis of other medically important fungi is recognized, little is known about their function in P. brasiliensis cells and PCM pathogenesis. We cloned the PbPga1 gene that codifies for a predicted GPI-anchored glycoprotein from the dimorphic pathogenic fungus P. brasiliensis. PbPga1 is conserved in Eurotiomycetes fungi and encodes for a protein with potential glycosylation sites in a serine/threonine-rich region, a signal peptide and a putative glycosylphosphatidylinositol attachment signal sequence. Specific chicken anti-rPbPga1 antibody localized PbPga1 on the yeast cell surface at the septum between the mother cell and the bud with stronger staining of the bud. The exposure of murine peritoneal macrophages to rPbPga1 induces TNF-α release and nitric oxide (NO production by macrophages. Furthermore, the presence of O-glycosylation sites was demonstrated by β-elimination under ammonium hydroxide treatment of rPbPga1. Finally, sera from PCM patients recognized rPbPga1 by Western blotting indicating the presence of specific antibodies against rPbPga1. In conclusion, our findings suggest that the PbPga1gene codifies for a cell surface glycoprotein, probably attached to a GPI-anchor, which may play a role in P. brasiliensis cell wall morphogenesis and infection. The induction of inflammatory mediators released by rPbPga1 and the reactivity of PCM patient sera toward rPbPga1 imply that the protein favors the innate mechanisms of defense and induces humoral immunity during P. brasiliensis infection.

  15. Tobraviruses--plant pathogens and tools for biotechnology.

    Science.gov (United States)

    Macfarlane, Stuart A

    2010-07-01

    The tobraviruses, Tobacco rattle virus (TRV), Pea early-browning virus (PEBV) and Pepper ringspot virus (PepRSV), are positive-strand RNA viruses with rod-shaped virus particles that are transmitted between plants by trichodorid nematodes. As a group, these viruses infect many plant species, with TRV having the widest host range. Recent studies have begun to dissect the interaction of TRV with potato, currently the most commercially important crop disease caused by any of the tobraviruses. As well as being successful plant pathogens, these viruses have become widely used as vectors for expression in plants of nonviral proteins or, more frequently, as initiators of virus-induced gene silencing (VIGS). Precisely why tobraviruses should be so effective as VIGS vectors is not known; however, molecular studies of the mode of action of the tobravirus silencing suppressor protein are shedding some light on this process.

  16. A common origin of rickettsiae and certain plant pathogens.

    Science.gov (United States)

    Weisburg, W G; Woese, C R; Dobson, M E; Weiss, E

    1985-11-01

    On the basis of ribosomal RNA sequence comparisons, the rickettsia Rochalimaea quintana has been found to be a member of subgroup 2 of the alpha subdivision of the so-called purple bacteria, which is one of about ten major eubacterial divisions. Within subgroup alpha-2, R. quintana is specifically related to the agrobacteria and rhizobacteria, organisms that also have close associations with eukaryotic cells. This genealogical grouping of the rickettsiae with certain plant pathogens and intracellular symbionts suggests a possible evolution of the rickettsiae from plant-associated bacteria.

  17. In vitro antifungal activity of fatty acid methyl esters of the seeds of Annona cornifolia A.St.-Hil. (Annonaceae) against pathogenic fungus Paracoccidioides brasiliensis.

    Science.gov (United States)

    Lima, Luciana Alves Rodrigues dos Santos; Johann, Susana; Cisalpino, Patrícia Silva; Pimenta, Lúcia Pinheiro Santos; Boaventura, Maria Amélia Diamantino

    2011-01-01

    Fatty acids are abundant in vegetable oils. They are known to have antibacterial and antifungal properties. Antifungal susceptibility was evaluated by broth microdilution assay following CLSI (formerly the NCCLS) guidelines against 16 fungal strains of clinical interest. In this work, fatty acid methyl esters (FAME) was able to inhibit 12 clinical strains of the pathogenic fungus Paracoccidioides brasiliensis and were also active in the bioautographic assay against Cladosporium sphaerospermum. FAME was a more potent antifungal than trimethoprim-sulfamethoxazole against P. brasiliensis under the experimental conditions tested.

  18. Evaluation of antifungal activity of aqueous extracts of some medicinal plants against Aspergillus flavus, pistachio aflatoxin producing fungus in vitro

    Directory of Open Access Journals (Sweden)

    Sahar Omidpanah

    2015-01-01

    Full Text Available Background: Contamination with aflatoxin, by Aspergillus flavus, is one the major challenges in agriculture and food industry. Preparation of organic products using natural components is widely considered these days. Aims: In this study, effects of aqueous extracts of five medicinal herbs, including thyme, senna, mentha, basil, and safflower on the growth of the A. flavus were investigated. Mterials and Methods: The extracts with different concentrations (200-800 µg/mL and polyethylene glycol with the equal osmotic potential of plant extracts were added to the potato dextrose agar medium to evaluate fungus growth after 7 days using agar dilution method. Benomyl, a fungicide, was used as a positive standard. The tests were performed in triplicate, and the mean diameters of fungus growth were calculated as well. Results and Conclusion: All concentrations of the plants extracts significantly inhibited the fungus growth in comparison with each other and control treatments, while the extracts of thyme and safflower manifested the most effective prohibition compared to benomyl with minimum inhibitory concentration of 200 and 400 µg/mL, respectively.

  19. The cAMP Signaling and MAP Kinase Pathways in Plant Pathogenic Fungi

    NARCIS (Netherlands)

    Mehrabi, R.; Zhao, X.; Kim, Y.; Xu, J.R.

    2009-01-01

    The key components of the well conserved cyclic AMP signaling and MAP kinase pathways have been functionally characterized in the corn smut Ustilago maydis, rice blast fungus Magnaporthe grisea, and a few other fungal pathogens. In general, the cAMP signaling and the MAP kinase cascade homologous to

  20. The symbiosis with the arbuscular mycorrhizal fungus Rhizophagus irregularis drives root water transport in flooded tomato plants.

    Science.gov (United States)

    Calvo-Polanco, Monica; Molina, Sonia; Zamarreño, Angel María; García-Mina, Jose María; Aroca, Ricardo

    2014-05-01

    It is known that the presence of arbuscular mycorrhizal fungi within the plant roots enhances the tolerance of the host plant to different environmental stresses, although the positive effect of the fungi in plants under waterlogged conditions has not been well studied. Tolerance of plants to flooding can be achieved through different molecular, physiological and anatomical adaptations, which will affect their water uptake capacity and therefore their root hydraulic properties. Here, we investigated the root hydraulic properties under non-flooded and flooded conditions in non-mycorrhizal tomato plants and plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. Only flooded mycorrhizal plants increased their root hydraulic conductivity, and this effect was correlated with a higher expression of the plant aquaporin SlPIP1;7 and the fungal aquaporin GintAQP1. There was also a higher abundance of the PIP2 protein phoshorylated at Ser280 in mycorrhizal flooded plants. The role of plant hormones (ethylene, ABA and IAA) in root hydraulic properties was also taken into consideration, and it was concluded that, in mycorrhizal flooded plants, ethylene has a secondary role regulating root hydraulic conductivity whereas IAA may be the key hormone that allows the enhancement of root hydraulic conductivity in mycorrhizal plants under low oxygen conditions.

  1. Interplay between parasitism and host ontogenic resistance in the epidemiology of the soil-borne plant pathogen Rhizoctonia solani.

    Directory of Open Access Journals (Sweden)

    Thomas E Simon

    Full Text Available Spread of soil-borne fungal plant pathogens is mainly driven by the amount of resources the pathogen is able to capture and exploit should it behave either as a saprotroph or a parasite. Despite their importance in understanding the fungal spread in agricultural ecosystems, experimental data related to exploitation of infected host plants by the pathogen remain scarce. Using Rhizoctonia solani / Raphanus sativus as a model pathosystem, we have obtained evidence on the link between ontogenic resistance of a tuberizing host and (i its susceptibility to the pathogen and (ii after infection, the ability of the fungus to spread in soil. Based on a highly replicable experimental system, we first show that infection success strongly depends on the host phenological stage. The nature of the disease symptoms abruptly changes depending on whether infection occurred before or after host tuberization, switching from damping-off to necrosis respectively. Our investigations also demonstrate that fungal spread in soil still depends on the host phenological stage at the moment of infection. High, medium, or low spread occurred when infection was respectively before, during, or after the tuberization process. Implications for crop protection are discussed.

  2. THE INFLUENCE OF ULTRAVIOLET LIGHT ON PATHOGENICITY OF ENTOMOPATHOGENIC FUNGUS BEAUVERIA BASSIANA (BALSAMO VUILLEMIN TO THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS HBN. (LEPIDOPTERA: CRAMBIDAE

    Directory of Open Access Journals (Sweden)

    L Cagán

    2002-05-01

    Full Text Available The influence of different doses of ultraviolet (UV light on the pathogenicity of entomopathogenic fungus Beauveria bassiana (Balsamo Vuillemin to the European corn borer, Ostrinia nubilalis Hbn., and radial growth of fungus was studied in laboratory conditions. The suspensions of B. bassiana isolate SK99 were exposed to UV light. Four different doses of UV light were used in the experiment. The distance between exposed suspensions and UV light source was 0.3 m. Exposure duration was 15, 30, 45 and 60 minutes (as A, B, C and D variants. Control variant SK99 and obtained variants SK99A, SK99B, SK99C and SK99D were cultivated 21 days on Sabourard-dextrose agar. The larvae of O. nubilalis were infected with dry powder consisted of mycelia and spores from fungus cultures. During 10 days, the mortality of infected larvae was evaluated. It was ascertained that UV light exposition significantly influenced the mortality effect of B. bassiana isolates to O. nubilalis larvae. Variant SK99C showed the highest level of infectivity. Radial growth of UV variants was slower with rising time of exposure. The best ability to grow possessed non-irradiated isolate SK99 and the worse variant SK99D. The difference between these two variants was significant.

  3. Pathogen filtration to control plant disease outbreak in greenhouse production

    Science.gov (United States)

    Jeon, Sangho; Krasnow, Charles; Bhalsod, Gemini; Granke, Leah; Harlan, Blair; Hausbeck, Mary; Zhang, Wei

    2016-04-01

    Previous research has been extensively focused on understanding the fate and transport of human microbial pathogens in soil and water environments. However, little is known about the transport of plant pathogens, although these pathogens are often found in irrigation waters and could cause severe crop damage and economical loss. Water mold pathogens including Phytophthora spp. and Pythium spp. are infective to a wide range of vegetable and floriculture crops, and they are primarily harbored in soils and disseminated through water flow. It is challenging to control these pathogens because they often quickly develop resistance to many fungicides. Therefore, this multi-scale study aimed to investigate physical removal of plant pathogens from water by filtration, thus reducing the pathogen exposure risks to crops. In column-scale experiments, we studied controlling factors on the transport and retention of Phytophthora capsici zoospores in saturated columns packed with iron oxide coated-sand and uncoated-sand under varying solution chemistry. Biflagellate zoospores were less retained than encysted zoospores, and lower solution pH and greater iron oxide content increased the retention of encysted zoospores. These results provided insights on environmental dispersal of Phytophthora zoospores in natural soils as well as on developing cost-effective engineered filtration systems for pathogen removal. Using small-scale greenhouse filtration systems, we further investigated the performance of varying filter media (i.e., granular sand, iron oxide coated ceramic porous media, and activated carbon) in mitigating disease outbreaks of Phytophthora and Pythium for greenhouse-grown squash and poinsettia, respectively, in comparison with fungicide treatment. For squash, filtration by iron oxide coated media was more effective in reducing the Phytophthora infection, comparing to sand filtration and fungicide application. For poinsettia, sand filtration performed better in controlling

  4. The rising threat of fungicide resistance in plant pathogenic fungi: Botrytis as a case study.

    Science.gov (United States)

    Hahn, Matthias

    2014-10-01

    The introduction of site-specific fungicides almost 50 years ago has revolutionized chemical plant protection, providing highly efficient, low toxicity compounds for control of fungal diseases. However, it was soon discovered that plant pathogenic fungi can adapt to fungicide treatments by mutations leading to resistance and loss of fungicide efficacy. The grey mould fungus Botrytis cinerea, a major cause of pre- and post-harvest losses in fruit and vegetable production, is notorious as a 'high risk' organism for rapid resistance development. In this review, the mechanisms and the history of fungicide resistance in Botrytis are outlined. The introduction of new fungicide classes for grey mould control was always followed by the appearance of resistance in field populations. In addition to target site resistance, B. cinerea has also developed a resistance mechanism based on drug efflux transport. Excessive spraying programmes have resulted in the selection of multiresistant strains in several countries, in particular in strawberry fields. The rapid erosion of fungicide activity against these strains represents a major challenge for the future of fungicides against Botrytis. To maintain adequate protection of intensive cultures against grey mould, strict implementation of resistance management measures are required as well as alternative strategies with non-chemical products.

  5. A novel high-affinity sucrose transporter is required for virulence of the plant pathogen Ustilago maydis.

    Directory of Open Access Journals (Sweden)

    Ramon Wahl

    2010-02-01

    Full Text Available Plant pathogenic fungi cause massive yield losses and affect both quality and safety of food and feed produced from infected plants. The main objective of plant pathogenic fungi is to get access to the organic carbon sources of their carbon-autotrophic hosts. However, the chemical nature of the carbon source(s and the mode of uptake are largely unknown. Here, we present a novel, plasma membrane-localized sucrose transporter (Srt1 from the corn smut fungus Ustilago maydis and its characterization as a fungal virulence factor. Srt1 has an unusually high substrate affinity, is absolutely sucrose specific, and allows the direct utilization of sucrose at the plant/fungal interface without extracellular hydrolysis and, thus, without the production of extracellular monosaccharides known to elicit plant immune responses. srt1 is expressed exclusively during infection, and its deletion strongly reduces fungal virulence. This emphasizes the central role of this protein both for efficient carbon supply and for avoidance of apoplastic signals potentially recognized by the host.

  6. The general transcriptional repressor Tup1 is required for dimorphism and virulence in a fungal plant pathogen.

    Directory of Open Access Journals (Sweden)

    Alberto Elías-Villalobos

    2011-09-01

    Full Text Available A critical step in the life cycle of many fungal pathogens is the transition between yeast-like growth and the formation of filamentous structures, a process known as dimorphism. This morphological shift, typically triggered by multiple environmental signals, is tightly controlled by complex genetic pathways to ensure successful pathogenic development. In animal pathogenic fungi, one of the best known regulators of dimorphism is the general transcriptional repressor, Tup1. However, the role of Tup1 in fungal dimorphism is completely unknown in plant pathogens. Here we show that Tup1 plays a key role in orchestrating the yeast to hypha transition in the maize pathogen Ustilago maydis. Deletion of the tup1 gene causes a drastic reduction in the mating and filamentation capacity of the fungus, in turn leading to a reduced virulence phenotype. In U. maydis, these processes are controlled by the a and b mating-type loci, whose expression depends on the Prf1 transcription factor. Interestingly, Δtup1 strains show a critical reduction in the expression of prf1 and that of Prf1 target genes at both loci. Moreover, we observed that Tup1 appears to regulate Prf1 activity by controlling the expression of the prf1 transcriptional activators, rop1 and hap2. Additionally, we describe a putative novel prf1 repressor, named Pac2, which seems to be an important target of Tup1 in the control of dimorphism and virulence. Furthermore, we show that Tup1 is required for full pathogenic development since tup1 deletion mutants are unable to complete the sexual cycle. Our findings establish Tup1 as a key factor coordinating dimorphism in the phytopathogen U. maydis and support a conserved role for Tup1 in the control of hypha-specific genes among animal and plant fungal pathogens.

  7. Fungal life-styles and ecosystem dynamics: biological aspects of plant pathogens, plant endophytes and saprophytes

    Science.gov (United States)

    Rodriguez, R.J.; Redman, R.S.

    1997-01-01

    This chapter discusses various biochemical, genetic, ecological, and evolutionary aspects of fungi that express either symbiotic or saprophytic life-styles. An enormous pool of potential pathogens exists in both agricultural and natural ecosystems, and virtually all plant species are susceptible to one or more fungal pathogens. Fungal pathogens have the potential to impact on the genetic structure of populations of individual plant species, the composition of plant communities and the process of plant succession. Endophytic fungi exist for at least part of their life cycles within the tissues of a plant host. This group of fungi is distinguished from plant pathogens because they do not elicit significant disease symptoms. However, endophytes do maintain the genetic and biochemical mechanisms required for infection and colonization of plant hosts. Fungi that obtain chemical nutrients from dead organic matter are known as saprophytes and are critical to the dynamics and resilience of ecosystems. There are two modes of saprophytic growth: one in which biomolecules that are amenable to transport across cell walls and membranes are directly absorbed, and another in which fungi must actively convert complex biopolymers into subunit forms amenable to transportation into cells. Regardless of life-style, fungi employ similar biochemical mechanisms for the acquisition and conversion of nutrients into complex biomolecules that are necessary for vegetative growth, production and dissemination of progeny, organismal competition, and survival during periods of nutrient deprivation or environmental inclemency.

  8. Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens.

    Science.gov (United States)

    Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

    2010-08-01

    Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling, and response to herbivores and pathogens has expanded rapidly in recent years, but information is generally lacking for parasitic species. In a recent paper we reported that some of the same defense responses induced by herbivores and pathogens--notably increases in jasmonic acid (JA), salicylic acid (SA), and a hypersensitive-like response (HLR)--also occur in tomato plants upon attack by the parasitic plant Cuscuta pentagona (field dodder). Parasitism induced a distinct pattern of JA and SA accumulation, and growth trials using genetically-altered tomato hosts suggested that both JA and SA govern effective defenses against the parasite, though the extent of the response varied with host plant age. Here we discuss similarities between the induced responses we observed in response to Cuscuta parasitism to those previously described for herbivores and pathogens and present new data showing that trichomes should be added to the list of plant defenses that act against multiple enemies and across Kingdoms.

  9. Deciphering the dual effect of lipopolysaccharides from plant pathogenic Pectobacterium.

    Science.gov (United States)

    Mohamed, Kettani-Halabi; Daniel, Tran; Aurélien, Dauphin; El-Maarouf-Bouteau, Hayat; Rafik, Errakhi; Arbelet-Bonnin, Delphine; Biligui, Bernadette; Florence, Val; Mustapha, Ennaji Moulay; François, Bouteau

    2015-01-01

    Lipopolysaccharides (LPS) are a component of the outer cell surface of almost all Gram-negative bacteria and play an essential role for bacterial growth and survival. Lipopolysaccharides represent typical microbe-associated molecular pattern (MAMP) molecules and have been reported to induce defense-related responses, including the expression of defense genes and the suppression of the hypersensitive response in plants. However, depending on their origin and the challenged plant, LPS were shown to have complex and different roles. In this study we showed that LPS from plant pathogens Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum induce common and different responses in A. thaliana cells when compared to those induced by LPS from non-phytopathogens Escherichia coli and Pseudomonas aeruginosa. Among common responses to both types of LPS are the transcription of defense genes and their ability to limit of cell death induced by Pectobacterium carotovorum subsp carotovorum. However, the differential kinetics and amplitude in reactive oxygen species (ROS) generation seemed to regulate defense gene transcription and be determinant to induce programmed cell death in response to LPS from the plant pathogenic Pectobacterium. These data suggest that different signaling pathways could be activated by LPS in A. thaliana cells.

  10. The root endophyte fungus Piriformospora indica leads to early flowering, higher biomass and altered secondary metabolites of the medicinal plant, Coleus forskohlii.

    Science.gov (United States)

    Das, Aparajita; Kamal, Shwet; Shakil, Najam Akhtar; Sherameti, Irena; Oelmüller, Ralf; Dua, Meenakshi; Tuteja, Narendra; Johri, Atul Kumar; Varma, Ajit

    2012-01-01

    This study was undertaken to investigate the influence of plant probiotic fungus Piriformospora indica on the medicinal plant C. forskohlii. Interaction of the C. forskohlii with the root endophyte P. indica under field conditions, results in an overall increase in aerial biomass, chlorophyll contents and phosphorus acquisition. The fungus also promoted inflorescence development, consequently the amount of p-cymene in the inflorescence increased. Growth of the root thickness was reduced in P. indica treated plants as they became fibrous, but developed more lateral roots. Because of the smaller root biomass, the content of forskolin was decreased. The symbiotic interaction of C. forskohlii with P. indica under field conditions promoted biomass production of the aerial parts of the plant including flower development. The plant aerial parts are important source of metabolites for medicinal application. Therefore we suggest that the use of the root endophyte fungus P. indica in sustainable agriculture will enhance the medicinally important chemical production.

  11. Genetic aspects of ash dieback caused by the pathogenic fungus Chalara fraxinea on Fraxinus excelsior

    DEFF Research Database (Denmark)

    McKinney, Lea Vig

    ). This thesis comprises five papers that aim to contribute to the knowledge on the interaction between the pathogen and its host and the inherent natural resistance found within the host species. Paper I reviews the current literature on the aetiology of the fungus, the epidemic and its consequences...... could be an effect of disease escape. The results suggest that a small fraction of the natural population may be able to resist the epidemic and proposes prospects for maintenance of the species through selection of highly resistant trees.......Ash dieback, caused by the invasive pathogen Chalara fraxinea T. Kowalski (teleomorph, Hymenoscyphus pseudoalbidus V. Queloz), has emerged and spread across Europe in the last two decades and currently affects most of the natural distribution of Fraxinus excelsior L. (common ash, European ash...

  12. Non-pathogenic Rhizobium radiobacter F4 deploys plant beneficial activity independent of its host Piriformospora indica.

    Science.gov (United States)

    Glaeser, Stefanie P; Imani, Jafargholi; Alabid, Ibrahim; Guo, Huijuan; Kumar, Neelendra; Kämpfer, Peter; Hardt, Martin; Blom, Jochen; Goesmann, Alexander; Rothballer, Michael; Hartmann, Anton; Kogel, Karl-Heinz

    2016-04-01

    The Alphaproteobacterium Rhizobium radiobacter F4 (RrF4) was originally characterized as an endofungal bacterium in the beneficial endophytic Sebacinalean fungus Piriformospora indica. Although attempts to cure P. indica from RrF4 repeatedly failed, the bacterium can easily be grown in pure culture. Here, we report on RrF4's genome and the beneficial impact the free-living bacterium has on plants. In contrast to other endofungal bacteria, the genome size of RrF4 is not reduced. Instead, it shows a high degree of similarity to the plant pathogenic R. radiobacter (formerly: Agrobacterium tumefaciens) C58, except vibrant differences in both the tumor-inducing (pTi) and the accessor (pAt) plasmids, which can explain the loss of RrF4's pathogenicity. Similar to its fungal host, RrF4 colonizes plant roots without host preference and forms aggregates of attached cells and dense biofilms at the root surface of maturation zones. RrF4-colonized plants show increased biomass and enhanced resistance against bacterial leaf pathogens. Mutational analysis showed that, similar to P. indica, resistance mediated by RrF4 was dependent on the plant's jasmonate-based induced systemic resistance (ISR) pathway. Consistent with this, RrF4- and P. indica-induced pattern of defense gene expression were similar. In clear contrast to P. indica, but similar to plant growth-promoting rhizobacteria, RrF4 colonized not only the root outer cortex but also spread beyond the endodermis into the stele. On the basis of our findings, RrF4 is an efficient plant growth-promoting bacterium.

  13. Plant genes involved in harbouring symbiotic rhizobia or pathogenic nematodes.

    Science.gov (United States)

    Damiani, Isabelle; Baldacci-Cresp, Fabien; Hopkins, Julie; Andrio, Emilie; Balzergue, Sandrine; Lecomte, Philippe; Puppo, Alain; Abad, Pierre; Favery, Bruno; Hérouart, Didier

    2012-04-01

    The establishment and development of plant-microorganism interactions involve impressive transcriptomic reprogramming of target plant genes. The symbiont (Sinorhizobium meliloti) and the root knot-nematode pathogen (Meloidogyne incognita) induce the formation of new root organs, the nodule and the gall, respectively. Using laser-assisted microdissection, we specifically monitored, at the cell level, Medicago gene expression in nodule zone II cells, which are preparing to receive rhizobia, and in gall giant and surrounding cells, which play an essential role in nematode feeding and constitute the typical root swollen structure, respectively. We revealed an important reprogramming of hormone pathways and C1 metabolism in both interactions, which may play key roles in nodule and gall neoformation, rhizobia endocytosis and nematode feeding. Common functions targeted by rhizobia and nematodes were mainly down-regulated, whereas the specificity of the interaction appeared to involve up-regulated genes. Our transcriptomic results provide powerful datasets to unravel the mechanisms involved in the accommodation of rhizobia and root-knot nematodes. Moreover, they raise the question of host specificity and the evolution of plant infection mechanisms by a symbiont and a pathogen.

  14. CRN13 candidate effectors from plant and animal eukaryotic pathogens are DNA-binding proteins which trigger host DNA damage response.

    Science.gov (United States)

    Ramirez-Garcés, Diana; Camborde, Laurent; Pel, Michiel J C; Jauneau, Alain; Martinez, Yves; Néant, Isabelle; Leclerc, Catherine; Moreau, Marc; Dumas, Bernard; Gaulin, Elodie

    2016-04-01

    To successfully colonize their host, pathogens produce effectors that can interfere with host cellular processes. Here we investigated the function of CRN13 candidate effectors produced by plant pathogenic oomycetes and detected in the genome of the amphibian pathogenic chytrid fungus Batrachochytrium dendrobatidis (BdCRN13). When expressed in Nicotiana, AeCRN13, from the legume root pathogen Aphanomyces euteiches, increases the susceptibility of the leaves to the oomycete Phytophthora capsici. When transiently expressed in amphibians or plant cells, AeCRN13 and BdCRN13 localize to the cell nuclei, triggering aberrant cell development and eventually causing cell death. Using Förster resonance energy transfer experiments in plant cells, we showed that both CRN13s interact with nuclear DNA and trigger plant DNA damage response (DDR). Mutating key amino acid residues in a predicted HNH-like endonuclease motif abolished the interaction of AeCRN13 with DNA, the induction of DDR and the enhancement of Nicotiana susceptibility to P. capsici. Finally, H2AX phosphorylation, a marker of DNA damage, and enhanced expression of genes involved in the DDR were observed in A. euteiches-infected Medicago truncatula roots. These results show that CRN13 from plant and animal eukaryotic pathogens promotes host susceptibility by targeting nuclear DNA and inducing DDR.

  15. The fungal pathogen Moniliophthora perniciosa has genes similar to plant PR-1 that are highly expressed during its interaction with cacao.

    Directory of Open Access Journals (Sweden)

    Paulo J P L Teixeira

    Full Text Available The widespread SCP/TAPS superfamily (SCP/Tpx-1/Ag5/PR-1/Sc7 has multiple biological functions, including roles in the immune response of plants and animals, development of male reproductive tract in mammals, venom activity in insects and reptiles and host invasion by parasitic worms. Plant Pathogenesis Related 1 (PR-1 proteins belong to this superfamily and have been characterized as markers of induced defense against pathogens. This work presents the characterization of eleven genes homologous to plant PR-1 genes, designated as MpPR-1, which were identified in the genome of Moniliophthora perniciosa, a basidiomycete fungus responsible for causing the devastating witches' broom disease in cacao. We describe gene structure, protein alignment and modeling analyses of the MpPR-1 family. Additionally, the expression profiles of MpPR-1 genes were assessed by qPCR in different stages throughout the fungal life cycle. A specific expression pattern was verified for each member of the MpPR-1 family in the conditions analyzed. Interestingly, some of them were highly and specifically expressed during the interaction of the fungus with cacao, suggesting a role for the MpPR-1 proteins in the infective process of this pathogen. Hypothetical functions assigned to members of the MpPR-1 family include neutralization of plant defenses, antimicrobial activity to avoid competitors and fruiting body physiology. This study provides strong evidence on the importance of PR-1-like genes for fungal virulence on plants.

  16. The fungal pathogen Moniliophthora perniciosa has genes similar to plant PR-1 that are highly expressed during its interaction with cacao.

    Science.gov (United States)

    Teixeira, Paulo J P L; Thomazella, Daniela P T; Vidal, Ramon O; do Prado, Paula F V; Reis, Osvaldo; Baroni, Renata M; Franco, Sulamita F; Mieczkowski, Piotr; Pereira, Gonçalo A G; Mondego, Jorge M C

    2012-01-01

    The widespread SCP/TAPS superfamily (SCP/Tpx-1/Ag5/PR-1/Sc7) has multiple biological functions, including roles in the immune response of plants and animals, development of male reproductive tract in mammals, venom activity in insects and reptiles and host invasion by parasitic worms. Plant Pathogenesis Related 1 (PR-1) proteins belong to this superfamily and have been characterized as markers of induced defense against pathogens. This work presents the characterization of eleven genes homologous to plant PR-1 genes, designated as MpPR-1, which were identified in the genome of Moniliophthora perniciosa, a basidiomycete fungus responsible for causing the devastating witches' broom disease in cacao. We describe gene structure, protein alignment and modeling analyses of the MpPR-1 family. Additionally, the expression profiles of MpPR-1 genes were assessed by qPCR in different stages throughout the fungal life cycle. A specific expression pattern was verified for each member of the MpPR-1 family in the conditions analyzed. Interestingly, some of them were highly and specifically expressed during the interaction of the fungus with cacao, suggesting a role for the MpPR-1 proteins in the infective process of this pathogen. Hypothetical functions assigned to members of the MpPR-1 family include neutralization of plant defenses, antimicrobial activity to avoid competitors and fruiting body physiology. This study provides strong evidence on the importance of PR-1-like genes for fungal virulence on plants.

  17. Vector-borne bacterial plant pathogens: Interactions with hemipteran insects and plants

    Directory of Open Access Journals (Sweden)

    Laura M Perilla-Henao

    2016-08-01

    Full Text Available Hemipteran insects are devastating pests of crops due to their wide host range, rapid reproduction, and ability to transmit numerous plant-infecting pathogens as vectors. While the field of plant-virus-vector interactions has flourished in recent years, plant-bacteria-vector interactions remain poorly understood. Leafhoppers and psyllids are by far the most important vectors of bacterial pathogens, yet there are still significant gaps in our understanding of their feeding behavior, salivary secretions, and plant responses as compared to important viral vectors, such as whiteflies and aphids. Even with an incomplete understanding of plant-bacteria-vector interactions, some common themes have emerged: 1 all known vector-borne bacteria share the ability to propagate in the plant and insect host; 2 particular hemipteran families appear to be incapable of transmitting vector-borne bacteria; 3 all known vector-borne bacteria have highly reduced genomes and coding capacity, resulting in host-dependence; and 4 vector-borne bacteria encode proteins that are essential for colonization of specific hosts, though only a few types of proteins have been investigated. Here, we review the current knowledge on important vector-borne bacterial pathogens, including Xylella fastidiosa, Spiroplasma spp., Liberibacter spp., and 'Candidatus Phytoplasma spp.’. We then highlight recent approaches used in the study of vector-borne bacteria. Finally, we discuss the application of this knowledge for control and future directions that will need to be addressed in the field of vector-plant-bacteria interactions.

  18. Genetic variability in the endophytic fungus Guignardia citricarpa isolated from citrus plants

    Directory of Open Access Journals (Sweden)

    Chirlei Glienke-Blanco

    2002-01-01

    Full Text Available During some phases of of their life-cycle endophytic fungi colonize plants asymptomatically being found most frequently inside the aerial part of plant tissues. After surface disinfection of apparently healthy leaves from three varieties of mandarin orange and one tangor, and after incubation on appropriate culture medium, 407 fungal isolates were obtained, giving a total infection frequency of 81%. No fungal growth was observed from disinfected seeds, indicating that fungi are probably not transmitted via seeds. Of the fungal isolates, 27% belonged to the genus Guignardia, with 12 isolates being identified as Guignardia citricarpa Kiely, which is described as a citrus pathogen. The isolates were variable in respect to the presence of sexual structures and growth rates. Most of the isolates produces mature asci, supporting the hypothesis that they are nonpathogenic endophytes, which recently were identified as G. mangiferae. High intraspecific genetic variability (an average similarity coefficient of 0.6 was detected using random amplified polymorphic DNA (RAPD markers generated by seven different primers. The highest similarity coefficient (0.9 was between isolates P15 and M86 and the smallest (0.22 between isolates P15 and C145. These results did not allow us to establish an association between genetic similarity of the fungal isolates and the citrus varieties from which they were obtained.

  19. Two herbivore-deterrent iridoid glycosides reduce the in-vitro growth of a specialist but not of a generalist pathogenic fungus of Plantago lanceolata L.

    NARCIS (Netherlands)

    Marak, H.B.; Biere, A.; Van Damme, J.M.M.

    2002-01-01

    Many secondary plant compounds are involved in defense against both insect herbivores and pathogens. Two secondary plant compounds of Plantago lanceolata, the iridoid glycosides catalpol and its precursor aucubin, are well known for their deterrent effects on generalist and non-adapted specialist in

  20. Antimicrobial activity of plant extracts against sexually transmitted pathogens.

    Science.gov (United States)

    Jadhav, Nutan; Kulkarni, Sangeeta; Mane, Arati; Kulkarni, Roshan; Palshetker, Aparna; Singh, Kamalinder; Joshi, Swati; Risbud, Arun; Kulkarni, Smita

    2015-01-01

    Comprehensive management of sexually transmitted infections (STIs) using vaginal or rectal microbicide-based intervention is one of the strategies for prevention of HIV infection. Herbal products have been used for treating STIs traditionally. Herein, we present in vitro activity of 10 plant extracts and their 34 fractions against three sexually transmitted/reproductive tract pathogens - Neisseria gonorrhoeae, Haemophilus ducreyi and Candida albicans. The plant parts were selected; the extracts/fractions were prepared and screened by disc diffusion method. The minimum inhibitory and minimum cidal concentrations were determined. The qualitative phytochemical analysis of selected extracts/fractions showing activity was performed. Of the extracts/fractions tested, three inhibited C. albicans, ten inhibited N. gonorrhoeae and five inhibited H. ducreyi growth. Our study demonstrated that Terminalia paniculata Roth. extracts/fractions inhibited growth of all three organisms. The ethyl acetate fraction of Syzygium cumini Linn. and Bridelia retusa (L.) Spreng. extracts was found to inhibit N. gonorrhoeae at lowest concentrations.

  1. Host cell modulation by human, animal and plant pathogens.

    Science.gov (United States)

    Andersson, Siv G E; Kempf, Volkhard A J

    2004-04-01

    Members of the alpha-proteobacteria display a broad range of interactions with higher eukaryotes. Some are pathogens of humans, such as Rickettsia and Bartonella that are associated with diseases like epidemic typhus, trench fever, cat scratch disease and bacillary angiomatosis. Others like the Brucella cause abortions in pregnant animals. Yet other species have evolved elaborate interactions with plants; in this group we find both plant symbionts and parasites. Despite radically different host preferences, extreme genome size variations and the absence of toxin genes, similarities in survival strategies and host cell interactions can be recognized among members of the alpha-proteobacteria. Here, we review some of these similarities, with a focus on strategies for modulation of the host target cell.

  2. Volatile antimicrobials from Muscodor crispans, a novel endophytic fungus.

    Science.gov (United States)

    Mitchell, Angela M; Strobel, Gary A; Moore, Emily; Robison, Richard; Sears, Joe

    2010-01-01

    Muscodor crispans is a recently described novel endophytic fungus of Ananas ananassoides (wild pineapple) growing in the Bolivian Amazon Basin. The fungus produces a mixture of volatile organic compounds (VOCs); some of the major components of this mixture, as determined by GC/MS, are propanoic acid, 2-methyl-, methyl ester; propanoic acid, 2-methyl-; 1-butanol, 3-methyl-;1-butanol, 3-methyl-, acetate; propanoic acid, 2-methyl-, 2-methylbutyl ester; and ethanol. The fungus does not, however, produce naphthalene or azulene derivatives as has been observed with many other members of the genus Muscodor. The mixture of VOCs produced by M. crispans cultures possesses antibiotic properties, as does an artificial mixture of a majority of the components. The VOCs of the fungus are effective against a wide range of plant pathogens, including the fungi Pythium ultimum, Phytophthora cinnamomi, Sclerotinia sclerotiorum and Mycosphaerella fijiensis (the black sigatoka pathogen of bananas), and the serious bacterial pathogen of citrus, Xanthomonas axonopodis pv. citri. In addition, the VOCs of M. crispans killed several human pathogens, including Yersinia pestis, Mycobacterium tuberculosis and Staphylococcus aureus. Artificial mixtures of the fungal VOCs were both inhibitory and lethal to a number of human and plant pathogens, including three drug-resistant strains of Mycobacterium tuberculosis. The gaseous products of Muscodor crispans potentially could prove to be beneficial in the fields of medicine, agriculture, and industry.

  3. Making healthier or killing enemies? Bacterial volatile-elicited plant immunity plays major role upon protection of Arabidopsis than the direct pathogen inhibition.

    Science.gov (United States)

    Sharifi, Rouhallah; Ryu, Choong-Min

    2016-01-01

    Bacterial volatiles protect plants either by directly inhibiting a pathogenic fungus or by improving the defense capabilities of plants. The effect of bacterial volatiles on fungal growth was dose-dependent. A low dosage did not have a noticeable effect on Botrytis cinerea growth and development, but was sufficient to elicit induced resistance in Arabidopsis thaliana. Bacterial volatiles displayed negative effects on biofilm formation on a polystyrene surface and in in planta leaf colonization of B. cinerea. However, bacterial volatile-mediated induced resistance was the major mechanism mediating protection of plants from B. cinerea. It was responsible for more than 90% of plant protection in comparison with direct fungal inhibition. Our results broaden our knowledge of the role of bacterial volatiles in plant protection.

  4. Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper.

    Science.gov (United States)

    Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

    2012-07-01

    Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.

  5. Chemosensitization of plant pathogenic fungi to agricultural fungicides.

    Directory of Open Access Journals (Sweden)

    Vitaly eDzhavakhiya

    2012-03-01

    Full Text Available A common consequence of using agricultural fungicides is the development of resistance by fungal pathogens, which undermines reliability of fungicidal effectiveness. A potentially new strategy to aid in overcoming or minimizing this problem is enhancement of pathogen sensitivity to fungicides, or chemosensitization. Chemosensitization can be accomplished by combining a commercial fungicide with a certain non- or marginally fungicidal substance at levels where, alone, neither compound would be effective. Chemosensitization decreases the probability of the pathogen developing resistance, reduces the toxic impact on the environment by lowering effective dosage levels of toxic fungicides, and improves efficacy of antifungal agents. The present study shows that the antifungal activity of azole and strobilurin fungicides can be significantly enhanced through their co-application with certain natural or synthetic products against several economically important plant pathogenic fungi. Quadris (azoxystrobin combined with thymol at a non-fungitoxic concentration produced much higher growth inhibition of Bipolaris sorokiniana, Phoma glomerata, Alternaria sp. and Stagonospora nodorum than the fungicide alone. The effect of Dividend (difenoconazole applied with thymol significantly enhanced antifungal activity against B. sorokiniana and S. nodorum. Folicur (tebuconazole combined with 4-hydroxybenzaldehyde (4-HBA, 2,3-dihydroxybenzaldehyde or thymol significantly inhibited growth of A. alternata, at a much greater level than the fungicide alone. In addition, co-application of Folicur and 4-HBA resulted in a similar enhancement of antifungal activity against Fusarium culmorum. Lastly, we discovered that metabolites in the culture liquid of F. sambucinum biocontrol isolate FS-94 also had chemosensitizing activity, increasing S. nodorum sensitivity to Folicur and Dividend.

  6. Chemosensitization of plant pathogenic fungi to agricultural fungicides.

    Science.gov (United States)

    Dzhavakhiya, Vitaly; Shcherbakova, Larisa; Semina, Yulia; Zhemchuzhina, Natalia; Campbell, Bruce

    2012-01-01

    A common consequence of using agricultural fungicides is the development of resistance by fungal pathogens, which undermines reliability of fungicidal effectiveness. A potentially new strategy to aid in overcoming or minimizing this problem is enhancement of pathogen sensitivity to fungicides, or "chemosensitization." Chemosensitization can be accomplished by combining a commercial fungicide with a certain non- or marginally fungicidal substance at levels where, alone, neither compound would be effective. Chemosensitization decreases the probability of the pathogen developing resistance, reduces the toxic impact on the environment by lowering effective dosage levels of toxic fungicides, and improves efficacy of antifungal agents. The present study shows that the antifungal activity of azole and strobilurin fungicides can be significantly enhanced through their co-application with certain natural or synthetic products against several economically important plant pathogenic fungi. Quadris (azoxystrobin) combined with thymol at a non-fungitoxic concentration produced much higher growth inhibition of Bipolaris sorokiniana, Phoma glomerata, Alternaria sp. and Stagonospora nodorum than the fungicide alone. The effect of Dividend (difenoconazole) applied with thymol significantly enhanced antifungal activity against B. sorokiniana and S. nodorum. Folicur (tebuconazole) combined with 4-hydroxybenzaldehyde (4-HBA), 2,3-dihydroxybenzaldehyde or thymol significantly inhibited growth of Alternaria alternata, at a much greater level than the fungicide alone. In addition, co-application of Folicur and 4-HBA resulted in a similar enhancement of antifungal activity against Fusarium culmorum. Lastly, we discovered that metabolites in the culture liquid of Fusarium sambucinum biocontrol isolate FS-94 also had chemosensitizing activity, increasing S. nodorum sensitivity to Folicur and Dividend.

  7. Foliar endophytic fungi as potential protectors from pathogens in myrmecophytic Acacia plants.

    Science.gov (United States)

    González-Teuber, Marcia; Jiménez-Alemán, Guillermo H; Boland, Wilhelm

    2014-10-01

    In defensive ant-plant interactions myrmecophytic plants express reduced chemical defense in their leaves to protect themselves from pathogens, and it seems that mutualistic partners are required to make up for this lack of defensive function. Previously, we reported that mutualistic ants confer plants of Acacia hindsii protection from pathogens, and that the protection is given by the ant-associated bacteria. Here, we examined whether foliar endophytic fungi may potentially act as a new partner, in addition to mutualistic ants and their bacteria inhabitants, involved in the protection from pathogens in myrmecophytic Acacia plants. Fungal endophytes were isolated from the asymptomatic leaves of A. hindsii plants for further molecular identification of 18S rRNA gene. Inhibitory effects of fungal endophytes were tested against Pseudomonas plant pathogens. Our findings support a potential role of fungal endophytes in pathogen the protection mechanisms against pathogens in myrmecophytic plants and provide the evidence of novel fungal endophytes capable of biosynthesizing bioactive metabolites.

  8. From Glacier to Sauna: RNA-Seq of the Human Pathogen Black Fungus Exophiala dermatitidis under Varying Temperature Conditions Exhibits Common and Novel Fungal Response.

    Directory of Open Access Journals (Sweden)

    Barbara Blasi

    Full Text Available Exophiala dermatitidis (Wangiella dermatitidis belongs to the group of the so-called black yeasts. Thanks in part to its thick and strongly melanized cell walls, E. dermatitidis is extremely tolerant to various kinds of stress, including extreme pH, temperature and desiccation. E. dermatitidis is also the agent responsible for various severe illnesses in humans, such as pneumonia and keratitis, and might lead to fatal brain infections. Due to its association with the human environment, its poly-extremophilic lifestyle and its pathogenicity in humans, E. dermatitidis has become an important model organism. In this study we present the functional analysis of the transcriptional response of the fungus at 1°C and 45°C, in comparison with that at 37°C, for two different exposition times, i.e. 1 hour and 1 week. At 1°C, E. dermatitidis uses a large repertoire of tools to acclimatize, such as lipid membrane fluidization, trehalose production or cytoskeleton rearrangement, which allows the fungus to remain metabolically active. At 45°C, the fungus drifts into a replicative state and increases the activity of the Golgi apparatus. As a novel finding, our study provides evidence that, apart from the protein coding genes, non-coding RNAs, circular RNAs as well as fusion-transcripts are differentially regulated and that the function of the fusion-transcripts can be related to the corresponding temperature condition. This work establishes that E. dermatitidis adapts to its environment by modulating coding and non-coding gene transcription levels and through the regulation of chimeric and circular RNAs.

  9. From Glacier to Sauna: RNA-Seq of the Human Pathogen Black Fungus Exophiala dermatitidis under Varying Temperature Conditions Exhibits Common and Novel Fungal Response.

    Science.gov (United States)

    Blasi, Barbara; Tafer, Hakim; Tesei, Donatella; Sterflinger, Katja

    2015-01-01

    Exophiala dermatitidis (Wangiella dermatitidis) belongs to the group of the so-called black yeasts. Thanks in part to its thick and strongly melanized cell walls, E. dermatitidis is extremely tolerant to various kinds of stress, including extreme pH, temperature and desiccation. E. dermatitidis is also the agent responsible for various severe illnesses in humans, such as pneumonia and keratitis, and might lead to fatal brain infections. Due to its association with the human environment, its poly-extremophilic lifestyle and its pathogenicity in humans, E. dermatitidis has become an important model organism. In this study we present the functional analysis of the transcriptional response of the fungus at 1°C and 45°C, in comparison with that at 37°C, for two different exposition times, i.e. 1 hour and 1 week. At 1°C, E. dermatitidis uses a large repertoire of tools to acclimatize, such as lipid membrane fluidization, trehalose production or cytoskeleton rearrangement, which allows the fungus to remain metabolically active. At 45°C, the fungus drifts into a replicative state and increases the activity of the Golgi apparatus. As a novel finding, our study provides evidence that, apart from the protein coding genes, non-coding RNAs, circular RNAs as well as fusion-transcripts are differentially regulated and that the function of the fusion-transcripts can be related to the corresponding temperature condition. This work establishes that E. dermatitidis adapts to its environment by modulating coding and non-coding gene transcription levels and through the regulation of chimeric and circular RNAs.

  10. The Herbivore-Induced Plant Volatiles Methyl Salicylate and Menthol Positively affect Growth and Pathogenicity of Entomopathogenic Fungi

    Science.gov (United States)

    Lin, Yongwen; Qasim, Muhammad; Hussain, Mubasher; Akutse, Komivi Senyo; Avery, Pasco Bruce; Dash, Chandra Kanta; Wang, Liande

    2017-01-01

    Some herbivore-induced-plant volatiles (HIPVs) compounds are vital for the functioning of an ecosystem, by triggering multi-trophic interactions for natural enemies, plants and herbivores. However, the effect of these chemicals, which play a crucial role in regulating the multi-trophic interactions between plant-herbivore-entomopathogenic fungi, is still unknown. To fill this scientific gap, we therefore investigated how these chemicals influence the entomopathogenic fungi growth and efficacy. In this study, Lipaphis erysimi induced Arabidopsis thaliana HIPVs were collected using headspace system and detected with GC-MS, and then analyzed the effects of these HIPVs chemicals on Lecanicillium lecanii strain V3450. We found that the HIPVs menthol and methyl salicylate at 1 and 10 nmol·ml−1 improved many performance aspects of the fungus, such as germination, sporulation, appressorial formation as well as its pathogenicity and virulence. These findings are not only important for understanding the multi-trophic interactions in an ecosystem, but also would contribute for developing new and easier procedures for conidial mass production as well as improve the pathogenicity and virulence of entomopathogenic fungi in biological pest management strategies. PMID:28079180

  11. The Herbivore-Induced Plant Volatiles Methyl Salicylate and Menthol Positively affect Growth and Pathogenicity of Entomopathogenic Fungi

    Science.gov (United States)

    Lin, Yongwen; Qasim, Muhammad; Hussain, Mubasher; Akutse, Komivi Senyo; Avery, Pasco Bruce; Dash, Chandra Kanta; Wang, Liande

    2017-01-01

    Some herbivore-induced-plant volatiles (HIPVs) compounds are vital for the functioning of an ecosystem, by triggering multi-trophic interactions for natural enemies, plants and herbivores. However, the effect of these chemicals, which play a crucial role in regulating the multi-trophic interactions between plant-herbivore-entomopathogenic fungi, is still unknown. To fill this scientific gap, we therefore investigated how these chemicals influence the entomopathogenic fungi growth and efficacy. In this study, Lipaphis erysimi induced Arabidopsis thaliana HIPVs were collected using headspace system and detected with GC-MS, and then analyzed the effects of these HIPVs chemicals on Lecanicillium lecanii strain V3450. We found that the HIPVs menthol and methyl salicylate at 1 and 10 nmol·ml-1 improved many performance aspects of the fungus, such as germination, sporulation, appressorial formation as well as its pathogenicity and virulence. These findings are not only important for understanding the multi-trophic interactions in an ecosystem, but also would contribute for developing new and easier procedures for conidial mass production as well as improve the pathogenicity and virulence of entomopathogenic fungi in biological pest management strategies.

  12. Proteomic study of three component interactions:plant, pathogens and antagonistic fungi

    Institute of Scientific and Technical Information of China (English)

    Marra R; Turrà D; Scala F; Lorito M; Ambrosino P; Scala V; Romano C; Vinale F; Ferraioli S; Ruocco M; Carbone V; Woo S L

    2004-01-01

    @@ The molecular factors involved in the three-way interaction between plant, pathogenic fungi and antagonistic/biocontrol fungi, such as Trichoderma,are still poorly understood, even if they represent a matter of interest for improving crop management and developing new strategies for plant diseases control. The aim of this work is to investigate the components involved in this interaction and, for this purpose, a proteomic approach was used. 2-D maps of the protein extracts from the single components in various interactions between plants (potato, bean,tobacco or tomato), pathogens (Botrytis cinerea, Rhizoctonia solani or Pythium ultimum) and biocontrol fungi ( Trichoderma atroviride strain P1 or Trichoderma harzianum strain T22) were obtained. The protcome of each partner was collected separately and extracted by acetone precipitation in presence of trichloroacetic acid and a reducing agent (DTT). The extracted proteins were separated by isoelectrofocusing (IEF), using IPG (Immobilized pH gradient) strips, followed by SDS-PAGE. In order to improve resolution the separations were performed both on wide than narrow pH range and on different gel lengths. Differential spots were noted in the proteome of the three-way interaction when compared to each single component. These were further characterized by mass spectrometry and in silico analysis with the aim of identifying and cloning the relative genes. During the in vitro interaction of T. harzianum strain T22 with tomato and the culture filtrate or cell walls of pathogens,the spot number was higher than in the presence of pathogen biomass. In terms of Trichoderma differential proteins displayed on 2D gels, the most important changes were obtained in the presence of P. ultimum . During the in vivo interaction with tomato, the antagonist proteome changed much more in presence of soilborne fungi R. solani and P. ultimum than with the foliar fungus B. cinerea, both in terms of total and increased or novel spots In

  13. Ubiquity of insect-derived nitrogen transfer to plants by endophytic insect-pathogenic fungi: an additional branch of the soil nitrogen cycle.

    Science.gov (United States)

    Behie, Scott W; Bidochka, Michael J

    2014-03-01

    The study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungus Metarhizium robertsii. That is, the endophytic capability and insect pathogenicity of M. robertsii are coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in five Metarhizium species representing those with broad (M. robertsii, M. brunneum, and M. guizhouense) and narrower insect host ranges (M. acridum and M. flavoviride), as well as the insect-pathogenic fungi Beauveria bassiana and Lecanicillium lecanii. Insects were injected with (15)N-labeled nitrogen, and we tracked the incorporation of (15)N into two dicots, haricot bean (Phaseolus vulgaris) and soybean (Glycine max), and two monocots, switchgrass (Panicum virgatum) and wheat (Triticum aestivum), in the presence of these fungi in soil microcosms. All Metarhizium species and B. bassiana but not L. lecanii showed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high, M. robertsii was able to transfer insect-derived nitrogen to plants. Metarhizium spp. and B. bassiana have a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities.

  14. Induced release of a plant-defense volatile 'deceptively' attracts insect vectors to plants infected with a bacterial pathogen.

    Directory of Open Access Journals (Sweden)

    Rajinder S Mann

    Full Text Available Transmission of plant pathogens by insect vectors is a complex biological process involving interactions between the plant, insect, and pathogen. Pathogen-induced plant responses can include changes in volatile and nonvolatile secondary metabolites as well as major plant nutrients. Experiments were conducted to understand how a plant pathogenic bacterium, Candidatus Liberibacter asiaticus (Las, affects host preference behavior of its psyllid (Diaphorina citri Kuwayama vector. D. citri were attracted to volatiles from pathogen-infected plants more than to those from non-infected counterparts. Las-infected plants were more attractive to D. citri adults than non-infected plants initially; however after feeding, psyllids subsequently dispersed to non-infected rather than infected plants as their preferred settling point. Experiments with Las-infected and non-infected plants under complete darkness yielded similar results to those recorded under light. The behavior of psyllids in response to infected versus non-infected plants was not influenced by whether or not they were carriers of the pathogen. Quantification of volatile release from non-infected and infected plants supported the hypothesis that odorants mediate psyllid preference. Significantly more methyl salicylate, yet less methyl anthranilate and D-limonene, was released by infected than non-infected plants. Methyl salicylate was attractive to psyllids, while methyl anthranilate did not affect their behavior. Feeding on citrus by D. citri adults also induced release of methyl salicylate, suggesting that it may be a cue revealing location of conspecifics on host plants. Infected plants were characterized by lower levels of nitrogen, phosphorus, sulfur, zinc, and iron, as well as, higher levels of potassium and boron than non-infected plants. Collectively, our results suggest that host selection behavior of D. citri may be modified by bacterial infection of plants, which alters release of

  15. Identification of diverse mycoviruses through metatranscriptomics characterization of the viromes of five major fungal plant pathogens

    Science.gov (United States)

    Infection of plant pathogenic fungi by mycoviruses can attenuate their virulence on plants and vigor in culture. In this study, we described the viromes of 275 isolates of five widely dispersed plant pathogenic fungal species (Colletotrichum truncatum, Macrophomina phaseolina, Phomopsis longicolla, ...

  16. Avoidance of plants unsuitable for the symbiotic fungus in leaf-cutting ants: Learning can take place entirely at the colony dump.

    Science.gov (United States)

    Arenas, Andrés; Roces, Flavio

    2017-01-01

    Plants initially accepted by foraging leaf-cutting ants are later avoided if they prove unsuitable for their symbiotic fungus. Plant avoidance is mediated by the waste produced in the fungus garden soon after the incorporation of the unsuitable leaves, as foragers can learn plant odors and cues from the damaged fungus that are both present in the recently produced waste particles. We asked whether avoidance learning of plants unsuitable for the symbiotic fungus can take place entirely at the colony dump. In order to investigate whether cues available in the waste chamber induce plant avoidance in naïve subcolonies, we exchanged the waste produced by subcolonies fed either fungicide-treated privet leaves or untreated leaves and measured the acceptance of untreated privet leaves before and after the exchange of waste. Second, we evaluated whether foragers could perceive the avoidance cues directly at the dump by quantifying the visits of labeled foragers to the waste chamber. Finally, we asked whether foragers learn to specifically avoid untreated leaves of a plant after a confinement over 3 hours in the dump of subcolonies that were previously fed fungicide-treated leaves of that species. After the exchange of the waste chambers, workers from subcolonies that had access to waste from fungicide-treated privet leaves learned to avoid that plant. One-third of the labeled foragers visited the dump. Furthermore, naïve foragers learned to avoid a specific, previously unsuitable plant if exposed solely to cues of the dump during confinement. We suggest that cues at the dump enable foragers to predict the unsuitable effects of plants even if they had never been experienced in the fungus garden.

  17. Biodiversity in agricultural soils, sustainable plant production and control of plant pathogens

    Directory of Open Access Journals (Sweden)

    A. J. Reinecke

    2010-01-01

    Full Text Available Pathogens Soils are very heterogeneous substrates providing an environmental matrix with varying spatial and temporal gradients of pH, organic carbon, particle size distribution and moisture content. Chemical, physical as well as biological factors are operational and soil includes a vast variety of soil-dwelling invertebrates and microbes that interact with each other and the environment to influence plant productivity directly and indirectly. A review of recent literature on the role of soil biodiversity highlights the important role of soil invertebrates, notably earthworms, in influencing soil characteristics and soil borne plant pathogens. Earthworms are widely recognized as having critical functions in soil in regulating key processes that impact favourably on plant productivity and simultaneously eliminating or reducing soil borne diseases. The aim of this review is firstly to contribute towards a clarification of the role of soil biodiversity in general and to focus specifically on that of earthworms and their role in influencing plant pathogens and parasites. Evidence is provided that their activities can support plant productivity and suppress pathogens. Once the nature and extent of their role is better known and they are confirmed to support plant productivity to the extent that many soil biologists believe, the next logical step is to utilize knowledge of their ecology to create and manage favourable environmental conditions to ensure their survival and activity in agricultural soils. Agricultural management practices that favour soil organisms are also reviewed. Implementing these will make the services of soil biota available to improve and sustain agro-ecosystems. This requires a better understanding of the preferences and tolerance ranges of these organisms and their interactions before we can apply methodologies in general to manipulate environmental conditions to maximise the benefits that they may offer.

  18. Role of soil, crop debris, and a plant pathogen in Salmonella enterica contamination of tomato plants.

    Directory of Open Access Journals (Sweden)

    Jeri D Barak

    Full Text Available BACKGROUND: In the U.S., tomatoes have become the most implicated vehicle for produce-associated Salmonellosis with 12 outbreaks since 1998. Although unconfirmed, trace backs suggest pre-harvest contamination with Salmonella enterica. Routes of tomato crop contamination by S. enterica in the absence of direct artificial inoculation have not been investigated. METHODOLOGY/PRINCIPAL FINDINGS: This work examined the role of contaminated soil, the potential for crop debris to act as inoculum from one crop to the next, and any interaction between the seedbourne plant pathogen Xanthomonas campestris pv. vesicatoria and S. enterica on tomato plants. Our results show S. enterica can survive for up to six weeks in fallow soil with the ability to contaminate tomato plants. We found S. enterica can contaminate a subsequent crop via crop debris; however a fallow period between crop incorporation and subsequent seeding can affect contamination patterns. Throughout these studies, populations of S. enterica declined over time and there was no bacterial growth in either the phyllosphere or rhizoplane. The presence of X. campestris pv. vesicatoria on co-colonized tomato plants had no effect on the incidence of S. enterica tomato phyllosphere contamination. However, growth of S. enterica in the tomato phyllosphere occurred on co-colonized plants in the absence of plant disease. CONCLUSIONS/SIGNIFICANCE: S. enterica contaminated soil can lead to contamination of the tomato phyllosphere. A six week lag period between soil contamination and tomato seeding did not deter subsequent crop contamination. In the absence of plant disease, presence of the bacterial plant pathogen, X. campestris pv. vesicatoria was beneficial to S. enterica allowing multiplication of the human pathogen population. Any event leading to soil contamination with S. enterica could pose a public health risk with subsequent tomato production, especially in areas prone to bacterial spot disease.

  19. Carbohydrate-related enzymes of important Phytophthora plant pathogens.

    Science.gov (United States)

    Brouwer, Henk; Coutinho, Pedro M; Henrissat, Bernard; de Vries, Ronald P

    2014-11-01

    Carbohydrate-Active enZymes (CAZymes) form particularly interesting targets to study in plant pathogens. Despite the fact that many CAZymes are pathogenicity factors, oomycete CAZymes have received significantly less attention than effectors in the literature. Here we present an analysis of the CAZymes present in the Phytophthora infestans, Ph. ramorum, Ph. sojae and Pythium ultimum genomes compared to growth of these species on a range of different carbon sources. Growth on these carbon sources indicates that the size of enzyme families involved in degradation of cell-wall related substrates like cellulose, xylan and pectin is not always a good predictor of growth on these substrates. While a capacity to degrade xylan and cellulose exists the products are not fully saccharified and used as a carbon source. The Phytophthora genomes encode larger CAZyme sets when compared to Py. ultimum, and encode putative cutinases, GH12 xyloglucanases and GH10 xylanases that are missing in the Py. ultimum genome. Phytophthora spp. also encode a larger number of enzyme families and genes involved in pectin degradation. No loss or gain of complete enzyme families was found between the Phytophthora genomes, but there are some marked differences in the size of some enzyme families.

  20. Microbial pathogens in wastewater treatment plants (WWTP) in Hamburg.

    Science.gov (United States)

    Ajonina, Caroline; Buzie, Christopher; Rubiandini, Rafi Herfini; Otterpohl, Ralf

    2015-01-01

    Microbial pathogens are among the major health problems associated with water and wastewater. Classical indicators of fecal contamination include total coliforms, Escherichia coli, and Clostridium perfringens. These fecal indicators were monitored in order to obtain information regarding their evolution during wastewater treatment processes. Helminth eggs survive for a long duration in the environment and have a high potential for waterborne transmission, making them reliable contaminant indicators. A large quantity of helminth eggs was detected in the wastewater samples using the Bailanger method. Eggs were found in the influent and effluent with average concentration ranging from 11 to 50 eggs/L. Both E. coli and total coliforms concentrations were significantly 1- to 3-fold higher in influent than in effluent. The average concentrations of E. coli ranged from 2.5×10(3) to 4.4×10(5) colony-forming units (CFU)/100 ml. Concentrations of total coliforms ranged from 3.6×10(3) to 7.9×10(5) CFU/100 ml. Clostridium perfringens was also detected in influent and effluent of wastewater treatment plants (WWTP) at average concentrations ranging from 5.4×10(2) to 9.1×10(2) most probable number (MPN)/100 ml. Significant Spearman rank correlations were found between helminth eggs and microbial indicators (total coliform, E. coli, and C. perfringens) in the WWTP. There is therefore need for additional microbial pathogen monitoring in the WWTP to minimize public health risk.

  1. The mycorrhizal fungus (¤Glomus intraradices¤) affects microbial activity in the rhizosphere of pea plants (¤Pisum sativum¤)

    DEFF Research Database (Denmark)

    Wamberg, C.; Christensen, S.; Jakobsen, I.

    2003-01-01

    Pea plants were grown in gamma-irradiated soil in pots with and without addition of the AM fungus Glomus intraradices at sufficient N and limiting P. Depending on the growth phase of the plant presence of AM had negative or positive effect on rhizosphere activity. Before flowering during nutrient...... in the rhizosphere community during plant growth also supported by changes in the bacteria (DGGE). (C) 2003 Elsevier Ltd. All rights reserved....

  2. Variation in genome organization of the plant pathogenic fungus Colletotrichum lindemuthianum.

    Science.gov (United States)

    O'Sullivan, D; Tosi, P; Creusot, F; Cooke, B M; Phan, T H; Dron, M; Langin, T

    1998-04-01

    The genome structure of Colletotrichum lindemuthianum in a set of diverse isolates was investigated using a combination of physical and molecular approaches. Flow cytometric measurement of genome size revealed significant variation between strains, with the smallest genome representing 59% of the largest. Southern-blot profiles of a cloned fungal telomere revealed a total chromosome number varying from 9 to 12. Chromosome separations using pulsed-field gel electrophoresis (PFGE) showed that these chromosomes belong to two distinct size classes: a variable number of small (< 2.5 Mb) polymorphic chromosomes and a set of unresolved chromosomes larger than 7 Mb. Two dispersed repeat elements were shown to cluster on distinct polymorphic minichromosomes. Single-copy flanking sequences from these repeat-containing clones specifically marked distinct small chromosomes. These markers were absent in some strains, indicating that part of the observed variability in genome organization may be explained by the presence or absence, in a given strain, of dispensable genomic regions and/or chromosomes.

  3. The plant cell nucleus: a true arena for the fight between plants and pathogens.

    Science.gov (United States)

    Deslandes, Laurent; Rivas, Susana

    2011-01-01

    Communication between the cytoplasm and the nucleus is a fundamental feature shared by both plant and animal cells. Cellular factors involved in the transport of macromolecules through the nuclear envelope, including nucleoporins, importins and Ran-GTP related components, are conserved among a variety of eukaryotic systems. Interestingly, mutations in these nuclear components compromise resistance signalling, illustrating the importance of nucleocytoplasmic trafficking in plant innate immunity. Indeed, spatial restriction of defence regulators by the nuclear envelope and stimulus-induced nuclear translocation constitute an important level of defence-associated gene regulation in plants. A significant number of effectors from different microbial pathogens are targeted to the plant cell nucleus. In addition, key host factors, including resistance proteins, immunity components, transcription factors and transcriptional regulators shuttle between the cytoplasm and the nucleus, and their level of nuclear accumulation determines the output of the defence response, further confirming the crucial role played by the nucleus during the interaction between plants and pathogens. Here, we discuss recent findings that situate the nucleus at the frontline of the mutual recognition between plants and invading microbes.

  4. Differential gene expression in Rhododendron fortunei roots colonized by an ericoid mycorrhizal fungus and increased nitrogen absorption and plant growth

    Directory of Open Access Journals (Sweden)

    Xiangying Wei

    2016-10-01

    Full Text Available Ericoid mycorrhizal (ERM fungi are specifically symbiotic with plants in the family Ericaceae. Little is known thus far about their symbiotic establishment and subsequent nitrogen (N uptake at the molecular level. The present study devised a system for establishing a symbiotic relationship between Rhododendron fortunei Lindl. and an ERM fungus (Oidiodendron maius var. maius strain Om19, quantified seedling growth and N uptake, and compared transcriptome profiling between colonized and uncolonized roots using RNA-Seq. The Om19 colonization induced 16,892 genes that were differentially expressed in plant roots, of which 14,364 were upregulated and 2,528 were downregulated. These genes included those homologous to ATP-binding cassette transporters, calcium/calmodulin-dependent kinases, and symbiosis receptor-like kinases. N metabolism was particularly active in Om19-colonized roots, and 51 genes were upregulated, such as nitrate transporters, nitrate reductase, nitrite reductase, ammonium transporters, glutamine synthetase, and glutamate synthase. Transcriptome analysis also identified a series of genes involving endocytosis, Fc-gamma R-mediated phagocytosis, glycerophospholipid metabolism, and GnRH signal pathway that have not been reported previously. Their roles in the symbiosis require further investigation. The Om19 colonization significantly increased N uptake and seedling growth. Total N content and dry weight of colonized seedlings were 36.6% and 46.6% greater than control seedlings. This is the first transcriptome analysis of a species from the family Ericaceae colonized by an ERM fungus. The findings from this study will shed light on the mechanisms underlying symbiotic relationships of ericaceous species with ERM fungi and the symbiosis-resultant N uptake and plant growth.

  5. Treatment of the effluent from a kraft bleach plant with the white-rot fungus Pleurotus ostreatoroseus sing

    Directory of Open Access Journals (Sweden)

    A.Z. Santos

    2002-12-01

    Full Text Available The ligninolytic fungus Pleurotus ostreatoroseus (synonymy of Pleurotus ëous was used to treat the first alkali extraction stage (E1 effluent of a kraft bleach plant. It was pelletized and used for two continuous experiments in a two-liter turbulent-flow bioreactor. In the first experiment, the average removal of color and of total phenols was 18.6 and 11.6%, respectively, after the addition of glucose. During the second experiment, which was developed with the addition of several quantities of glucose, the maximum removal of color, of total phenols and of lignin/chlorolignin was 19.4, 9.4 and 44.5%. For both experiments, the best results were obtained when the effluent was diluted and enriched with glucose. This indicated the need for an extra carbon source for the fungal treatment. Using the mycelial mass in suspension, three experiments were carried out. The best results were obtained with 20% fungus and shaking of the effluent. During the last three days of the experiment the average removal of color, of total phenols and of lignin/chlorolignin was 84.4± 6.1, 82.1± 5.7 and 72.4± 8.9, respectively. The results indicate the potential of Pleurotus ostreatoroseus for use in the treatment of E1 effluent.

  6. Evolution of filamentous plant pathogens: gene exchange across eukaryotic kingdoms.

    Science.gov (United States)

    Richards, Thomas A; Dacks, Joel B; Jenkinson, Joanna M; Thornton, Christopher R; Talbot, Nicholas J

    2006-09-19

    Filamentous fungi and oomycetes are eukaryotic microorganisms that grow by producing networks of thread-like hyphae, which secrete enzymes to break down complex nutrients, such as wood and plant material, and recover the resulting simple sugars and amino acids by osmotrophy. These organisms are extremely similar in both appearance and lifestyle and include some of the most economically important plant pathogens . However, the morphological similarity of fungi and oomycetes is misleading because they represent some of the most distantly related eukaryote evolutionary groupings, and their shared osmotrophic growth habit is interpreted as being the result of convergent evolution . The fungi branch with the animals, whereas the oomycetes branch with photosynthetic algae as part of the Chromalveolata . In this report, we provide strong phylogenetic evidence that multiple horizontal gene transfers (HGT) have occurred from filamentous ascomycete fungi to the distantly related oomycetes. We also present evidence that a subset of the associated gene families was initially the product of prokaryote-to-fungi HGT. The predicted functions of the gene products associated with fungi-to-oomycete HGT suggest that this process has played a significant role in the evolution of the osmotrophic, filamentous lifestyle on two separate branches of the eukaryote tree.

  7. Microbial populations responsible for specific soil suppressiveness to plant pathogens.

    Science.gov (United States)

    Weller, David M; Raaijmakers, Jos M; Gardener, Brian B McSpadden; Thomashow, Linda S

    2002-01-01

    Agricultural soils suppressive to soilborne plant pathogens occur worldwide, and for several of these soils the biological basis of suppressiveness has been described. Two classical types of suppressiveness are known. General suppression owes its activity to the total microbial biomass in soil and is not transferable between soils. Specific suppression owes its activity to the effects of individual or select groups of microorganisms and is transferable. The microbial basis of specific suppression to four diseases, Fusarium wilts, potato scab, apple replant disease, and take-all, is discussed. One of the best-described examples occurs in take-all decline soils. In Washington State, take-all decline results from the buildup of fluorescent Pseudomonas spp. that produce the antifungal metabolite 2,4-diacetylphloroglucinol. Producers of this metabolite may have a broader role in disease-suppressive soils worldwide. By coupling molecular technologies with traditional approaches used in plant pathology and microbiology, it is possible to dissect the microbial composition and complex interactions in suppressive soils.

  8. Dehydrin-like proteins in the necrotrophic fungus Alternaria brassicicola have a role in plant pathogenesis and stress response.

    Science.gov (United States)

    Pochon, Stéphanie; Simoneau, Philippe; Pigné, Sandrine; Balidas, Samuel; Bataillé-Simoneau, Nelly; Campion, Claire; Jaspard, Emmanuel; Calmes, Benoît; Hamon, Bruno; Berruyer, Romain; Juchaux, Marjorie; Guillemette, Thomas

    2013-01-01

    In this study, the roles of fungal dehydrin-like proteins in pathogenicity and protection against environmental stresses were investigated in the necrotrophic seed-borne fungus Alternaria brassicicola. Three proteins (called AbDhn1, AbDhn2 and AbDhn3), harbouring the asparagine-proline-arginine (DPR) signature pattern and sharing the characteristic features of fungal dehydrin-like proteins, were identified in the A. brassicicola genome. The expression of these genes was induced in response to various stresses and found to be regulated by the AbHog1 mitogen-activated protein kinase (MAPK) pathway. A knock-out approach showed that dehydrin-like proteins have an impact mainly on oxidative stress tolerance and on conidial survival upon exposure to high and freezing temperatures. The subcellular localization revealed that AbDhn1 and AbDhn2 were associated with peroxisomes, which is consistent with a possible perturbation of protective mechanisms to counteract oxidative stress and maintain the redox balance in AbDhn mutants. Finally, we show that the double deletion mutant ΔΔabdhn1-abdhn2 was highly compromised in its pathogenicity. By comparison to the wild-type, this mutant exhibited lower aggressiveness on B. oleracea leaves and a reduced capacity to be transmitted to Arabidopsis seeds via siliques. The double mutant was also affected with respect to conidiation, another crucial step in the epidemiology of the disease.

  9. Dehydrin-like proteins in the necrotrophic fungus Alternaria brassicicola have a role in plant pathogenesis and stress response.

    Directory of Open Access Journals (Sweden)

    Stéphanie Pochon

    Full Text Available In this study, the roles of fungal dehydrin-like proteins in pathogenicity and protection against environmental stresses were investigated in the necrotrophic seed-borne fungus Alternaria brassicicola. Three proteins (called AbDhn1, AbDhn2 and AbDhn3, harbouring the asparagine-proline-arginine (DPR signature pattern and sharing the characteristic features of fungal dehydrin-like proteins, were identified in the A. brassicicola genome. The expression of these genes was induced in response to various stresses and found to be regulated by the AbHog1 mitogen-activated protein kinase (MAPK pathway. A knock-out approach showed that dehydrin-like proteins have an impact mainly on oxidative stress tolerance and on conidial survival upon exposure to high and freezing temperatures. The subcellular localization revealed that AbDhn1 and AbDhn2 were associated with peroxisomes, which is consistent with a possible perturbation of protective mechanisms to counteract oxidative stress and maintain the redox balance in AbDhn mutants. Finally, we show that the double deletion mutant ΔΔabdhn1-abdhn2 was highly compromised in its pathogenicity. By comparison to the wild-type, this mutant exhibited lower aggressiveness on B. oleracea leaves and a reduced capacity to be transmitted to Arabidopsis seeds via siliques. The double mutant was also affected with respect to conidiation, another crucial step in the epidemiology of the disease.

  10. Growth, respiration and nutrient acquisition by the arbuscular mycorrhizal fungus Glomus mosseae and its host plant Plantago lanceolata in cooled soil.

    Science.gov (United States)

    Karasawa, T; Hodge, A; Fitter, A H

    2012-04-01

    Although plant phosphate uptake is reduced by low soil temperature, arbuscular mycorrhizal (AM) fungi are responsible for P uptake in many plants. We investigated growth and carbon allocation of the AM fungus Glomus mosseae and a host plant (Plantago lanceolata) under reduced soil temperature. Plants were grown in compartmented microcosm units to determine the impact on both fungus and roots of a constant 2.7 °C reduction in soil temperature for 16 d. C allocation was measured using two (13)CO(2) pulse labels. Although root growth was reduced by cooling, AM colonization, growth and respiration of the extraradical mycelium (ERM) and allocation of assimilated (13)C to the ERM were all unaffected; the frequency of arbuscules increased. In contrast, root respiration and (13)C content and plant P and Zn content were all reduced by cooling. Cooling had less effect on N and K, and none on Ca and Mg content. The AM fungus G. mosseae was more able to sustain activity in cooled soil than were the roots of P. lanceolata, and so enhanced plant P content under a realistic degree of soil cooling that reduced plant growth. AM fungi may therefore be an effective means to promote plant nutrition under low soil temperatures.

  11. Nail Fungus

    Science.gov (United States)

    ... problems, a weakened immune system or, in children, Down syndrome A severe case of nail fungus can be ... possibly effective in treating nail fungus, but more study is needed. ... and file down thickened areas. Wear socks that absorb sweat. Fabrics ...

  12. Cyanide, a Coproduct of Plant Hormone Ethylene Biosynthesis, Contributes to the Resistance of Rice to Blast Fungus1[W][OA

    Science.gov (United States)

    Seo, Shigemi; Mitsuhara, Ichiro; Feng, Jiao; Iwai, Takayoshi; Hasegawa, Morifumi; Ohashi, Yuko

    2011-01-01

    Rice (Oryza sativa) plants carrying the Pi-i resistance gene to blast fungus Magnaporthe oryzae restrict invaded fungus in infected tissue via hypersensitive reaction or response (HR), which is accompanied by rapid ethylene production and formation of small HR lesions. Ethylene biosynthesis has been implicated to be important for blast resistance; however, the individual roles of ethylene and cyanide, which are produced from the precursor 1-aminocyclopropane-1-carboxylic acid, remain unevaluated. In this study, we found that Pi-i-mediated resistance was compromised in transgenic rice lines, in which ethylene biosynthetic enzyme genes were silenced and then ethylene production was inhibited. The compromised resistance in transgenic lines was recovered by exogenously applying cyanide but not ethephon, an ethylene-releasing chemical in plant tissue. In a susceptible rice cultivar, treatment with cyanide or 1-aminocyclopropane-1-carboxylic acid induced the resistance to blast fungus in a dose-dependent manner, while ethephon did not have the effect. Cyanide inhibited the growth of blast fungus in vitro and in planta, and application of flavonoids, secondary metabolites that exist ubiquitously in the plant kingdom, enhanced the cyanide-induced inhibition of fungal growth. These results suggested that cyanide, whose production is triggered by HR in infected tissue, contributes to the resistance in rice plants via restriction of fungal growth. PMID:21075959

  13. A New Metabolite with a unique 4-pyranone-ylactam-1,4-thiazine moiety from a Hawaiian-plant associated fungus

    Science.gov (United States)

    An endophytic fungus Paraphaeosphaeria neglecta FT462 isolated from the Hawaiian-plant Lycopodiella cernua (L.) Pic. Serm produced one unusual compound (1, paraphaeosphaeride A) with the 4-pyranone-'-lactam-1,4-thiazine moiety, along with two new compounds (2 and 3, paraphaeosphaerides B and C, resp...

  14. Plant growth regulators in poplar clones differing in resistance to the fungus Ceratocystis fimbriata Ell. et Haist

    Directory of Open Access Journals (Sweden)

    Jadwiga Stopińska

    2014-02-01

    Full Text Available In poplar clones with different resistance to the fungus Ceratocystis fimbriata growth of shoots, intensity of transpiration and the level of endogenous growth regulators were determined. More resistant clones, Populus 'Robusta' and P. 'PK-136-2' (P. nigra 'Italica': x P. laurifolia had more intensive growth of shoots, higher water content in leaves and a lower intensity of transpiration than the more susceptible clone, - P. 'NE-42' (P. maximowiczi x P. trichocarpa. The leaves of the more resistant clones contained more auxins (IAA and cytokinins, especially zeatin, and less growth inhibitors (ABA than those of the susceptible one. The level of plant growth regulators and/or the relations betweeen them may be responsible for the different poplar resistance to C. fimbriata.

  15. Prevalence and pathogen load estimates for the fungus Batrachochytrium dendrobatidis are impacted by ITS DNA copy number variation.

    Science.gov (United States)

    Rebollar, Eria A; Woodhams, Douglas C; LaBumbard, Brandon; Kielgast, Jos; Harris, Reid N

    2017-03-21

    The ribosomal gene complex is a multi-copy region that is widely used for phylogenetic analyses of organisms from all 3 domains of life. In fungi, the copy number of the internal transcribed spacer (ITS) is used to detect abundance of pathogens causing diseases such as chytridiomycosis in amphibians and white nose syndrome in bats. Chytridiomycosis is caused by the fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), and is responsible for declines and extinctions of amphibians worldwide. Over a decade ago, a qPCR assay was developed to determine Bd prevalence and pathogen load. Here, we demonstrate the effect that ITS copy number variation in Bd strains can have on the estimation of prevalence and pathogen load. We used data sets from different amphibian species to simulate how ITS copy number affects prevalence and pathogen load. In addition, we tested 2 methods (gBlocks® synthetic standards and digital PCR) to determine ITS copy number in Bd strains. Our results show that assumptions about the ITS copy number can lead to under- or overestimation of Bd prevalence and pathogen load. The use of synthetic standards replicated previously published estimates of ITS copy number, whereas dPCR resulted in estimates that were consistently lower than previously published estimates. Standardizing methods will assist with comparison across studies and produce reliable estimates of prevalence and pathogen load in the wild, while using the same Bd strain for exposure experiments and zoospore standards in qPCR remains the best method for estimating parameters used in epidemiological studies.

  16. Appressorium formation in the corn smut fungus Ustilago maydis requires a G2 cell cycle arrest.

    Science.gov (United States)

    Castanheira, Sónia; Pérez-Martín, José

    2015-01-01

    Many of the most important plant diseases are caused by fungal pathogens that form specialized cell structures to breach the leaf surface as well as to proliferate inside the plant. To initiate pathogenic development, the fungus responds to a set of inductive cues. Some of them are of extracellular nature (environmental signals) while others respond to intracellular conditions (developmental signals). These signals have to be integrated into a single response that has as a major outcome changes in the morphogenesis of the fungus. The cell cycle regulation is pivotal during these cellular differentiations, and we hypothesized that cell cycle regulation would be likely to provide control points for infection development by fungal pathogens. Although efforts have been done in various fungal systems, there is still limited information available regarding the relationship of these processes with the induction of the virulence programs. Hence, the role of fungal cell cycle regulators -which are wide conserved elements- as true virulence factors, has yet to be defined. Here we discuss the recent finding that the formation of the appressorium, a structure required for plant penetration, in the corn smut fungus Ustilago maydis seems to be incompatible with an active cell cycle and, therefore genetic circuits evolved in this fungus to arrest the cell cycle during the growth of this fungus on plant surface, before the appressorium-mediated penetration into the plant tissue.

  17. Endophytic colonization of barley (Hordeum vulgare) roots by the nematophagous fungus Pochonia chlamydosporia reveals plant growth promotion and a general defense and stress transcriptomic response.

    Science.gov (United States)

    Larriba, Eduardo; Jaime, María D L A; Nislow, Corey; Martín-Nieto, José; Lopez-Llorca, Luis Vicente

    2015-07-01

    Plant crop yields are negatively conditioned by a large set of biotic and abiotic factors. An alternative to mitigate these adverse effects is the use of fungal biological control agents and endophytes. The egg-parasitic fungus Pochonia chlamydosporia has been traditionally studied because of its potential as a biological control agent of plant-parasitic nematodes. This fungus can also act as an endophyte in monocot and dicot plants, and has been shown to promote plant growth in different agronomic crops. An Affymetrix 22K Barley GeneChip was used in this work to analyze the barley root transcriptomic response to P. chlamydosporia root colonization. Functional gene ontology (GO) and gene set enrichment analyses showed that genes involved in stress response were enriched in the barley transcriptome under endophytism. An 87.5% of the probesets identified within the abiotic stress response group encoded heat shock proteins. Additionally, we found in our transcriptomic analysis an up-regulation of genes implicated in the biosynthesis of plant hormones, such as auxin, ethylene and jasmonic acid. Along with these, we detected induction of brassinosteroid insensitive 1-associated receptor kinase 1 (BR1) and other genes related to effector-triggered immunity (ETI) and pattern-triggered immunity (PTI). Our study supports at the molecular level the growth-promoting effect observed in plants endophytically colonized by P. chlamydosporia, which opens the door to further studies addressing the capacity of this fungus to mitigate the negative effects of biotic and abiotic factors on plant crops.

  18. Fluorescence techniques to detect and to assess viability of plant pathogenic bacteria

    NARCIS (Netherlands)

    Chitarra, L.G.

    2001-01-01

    Plant pathogenic bacteria cause major economic losses in commercial crop production worldwide every year. The current methods used to detect and to assess the viability of bacterial pathogens and to test seed lots or plants for contamination are usually based on plate assays or on serological techni

  19. Plant chemical defense against herbivores and pathogens: generalized defense or trade-offs?

    NARCIS (Netherlands)

    Biere, A.; Marak, H.B.; Van Damme, J.M.M.

    2004-01-01

    Plants are often attacked by multiple enemies, including pathogens and herbivores. While many plant secondary metabolites show specific effects toward either pathogens or herbivores, some can affect the performance of both these groups of natural enemies and are considered to be generalized defense

  20. A new resting trap to sample fungus-infected mosquitoes, and the pathogenicity of Lecanicillium muscarium to culicid adults

    NARCIS (Netherlands)

    Luz, C.; Mnyone, L.L.; Sangusangu, R.; Lyimo, I.N.; Rocha, L.F.N.; Humber, R.A.; Russell, T.L.

    2010-01-01

    Some soil-dwelling entomopathogenic fungi that are widely used in pest control are also able to reduce the survival of adult mosquito vectors under laboratory conditions. However, there is still little information about the naturally occurring fungal pathogens affecting culicid mosquitoes. As such,

  1. Plants as a habitat for beneficial and/or human pathogenic bacteria.

    Science.gov (United States)

    Tyler, Heather L; Triplett, Eric W

    2008-01-01

    Non-plant pathogenic endophytic bacteria can promote plant growth, improve nitrogen nutrition, and, in some cases, are human pathogens. Recent work in several laboratories has shown that enteric bacteria are common inhabitants of the interior of plants. These observations led to the experiments that showed the entry into plants of enteric human pathogens such as Salmonella and E. coli O157:H7. The extent of endophytic colonization by strains is regulated by plant defenses and several genetic determinants necessary for this interior colonization in endophytic bacteria have been identified. The genomes of four endophytic bacteria now available should promote discovery of other genes that contribute to this phenotype. Common virulence factors in plant and animal pathogens have also been described in bacteria that can infect both plant and animal models. Future directions in all of these areas are proposed.

  2. Cladosporium fulvum (syn. Passalora fulva), a highly specialized plant pathogen as a model for functional studies on plant pathogenic Mycosphaerellaceae

    NARCIS (Netherlands)

    Thomma, B.P.H.J.; Esse, van H.P.; Crous, P.W.; Wit, de P.J.G.M.

    2005-01-01

    Taxonomy: Cladosporium fulvum is an asexual fungus for which no sexual stage is currently known. Molecular data, however, support C. fulvum as a member of the Mycosphaerellaceae, clustering with other taxa having Mycosphaerella teleomorphs. C. fulvum has recently been placed in the anamorph genus Pa

  3. Anti-biotic Effect of Slightly Acidic Electrolyzed Water on Plant Bacterial / Fungal Pathogen

    OpenAIRE

    津野, 和宣; 中村, 悌一

    2012-01-01

    The anti-biotic effect of slightly acidic electrolyzed water on plant pathogen was determined. The spores of 4 kinds of fungal pathogen and 17 kinds of plant pathogenic bacteria were applied at different concentration.###Slightly acidic electrolyzed water showed strong growth inhibition in germination of fungi spores tested. In addition, by the treatment with slightly acidic electrolyzed water for 30 sec., all kinds of bacteria tested were inhibited to grow on the medium.###The anti-biotic ef...

  4. N-acyl-homoserine lactones-producing bacteria protect plants against plant and human pathogens.

    Science.gov (United States)

    Hernández-Reyes, Casandra; Schenk, Sebastian T; Neumann, Christina; Kogel, Karl-Heinz; Schikora, Adam

    2014-11-01

    The implementation of beneficial microorganisms for plant protection has a long history. Many rhizobia bacteria are able to influence the immune system of host plants by inducing resistance towards pathogenic microorganisms. In this report, we present a translational approach in which we demonstrate the resistance-inducing effect of Ensifer meliloti (Sinorhizobium meliloti) on crop plants that have a significant impact on the worldwide economy and on human nutrition. Ensifer meliloti is usually associated with root nodulation in legumes and nitrogen fixation. Here, we suggest that the ability of S. meliloti to induce resistance depends on the production of the quorum-sensing molecule, oxo-C14-HSL. The capacity to enhanced resistance provides a possibility to the use these beneficial bacteria in agriculture. Using the Arabidopsis-Salmonella model, we also demonstrate that the application of N-acyl-homoserine lactones-producing bacteria could be a successful strategy to prevent plant-originated infections with human pathogens. © 2014 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  5. Pathogenicity of Macrophomina phaseoli on Jute in the Presence of Meloidogyne incognita and Hoplolaimus indicus.

    Science.gov (United States)

    Haque, M D; Mukhopadhyaya, M C

    1979-10-01

    Seedlings of Corchorus capsularis (cv. C4444) were inoculated with Meloidogyne incognita, Hoplolaimus indicus, and a fungus pathogen of jute, Macrophomina phaseoli, separately and in all possible combinations. The significant damage of jute plants caused individually by the pathogens was aggravated when the fungus was associated with either of the nematode species. M. incognita alone caused greater damage than either H. indicus or Macrophomina phaseoli alone. Plants inoculated with M. incognita and Macrophomina phaseoli were more severely damaged than plants inoculated with H. indicus and the fungus. Plant growth was minimum and disease symptoms were maximum when all pathogens acted together. In the presence of the fungus, M. incognita produced fewer galls. The reproduction of H. indicus was not influenced by the other organisms.

  6. Fungus-mediated biosynthesis and characterization of TiO2 nanoparticles and their activity against pathogenic bacteria

    Science.gov (United States)

    Rajakumar, G.; Rahuman, A. Abdul; Roopan, S. Mohana; Khanna, V. Gopiesh; Elango, G.; Kamaraj, C.; Zahir, A. Abduz; Velayutham, K.

    2012-06-01

    In the present study, the biosynthesis of TiO2 nanoparticles (TiO2 NPs) was achieved by a novel, biodegradable and convenient procedure using Aspergillus flavus as a reducing and capping agent. Research on new, simple, rapid, eco-friendly and cheaper methods has been initiated. TiO2 NPs were characterized by FTIR, XRD, AFM, SEM and TEM studies. The X-ray diffraction showed the presence of increased amount of TiO2 NPs which can state by the presence of peaks at rutile peaks at 1 0 0, 0 0 2, 1 0 0 and anatase forms at 1 0 1 respectively. SEM observations revealed that synthesized TiO2 NPs were spherical, oval in shape; individual nanoparticles as well as a few aggregate having the size of 62-74 nm. AFM shows crystallization temperature was seen on the roughness of the surface of TiO2. The Minimum inhibitory concentration value for the synthesized TiO2 NPs was found to be 40 μg ml-1 for Escherichia coli, which was corresponding to the value of well diffusion test. This is the first report on antimicrobial activity of fungus-mediated synthesized TiO2 NPs, which was proved to be a good novel antibacterial material.

  7. Fungus-mediated biosynthesis and characterization of TiO₂ nanoparticles and their activity against pathogenic bacteria.

    Science.gov (United States)

    Rajakumar, G; Rahuman, A Abdul; Roopan, S Mohana; Khanna, V Gopiesh; Elango, G; Kamaraj, C; Zahir, A Abduz; Velayutham, K

    2012-06-01

    In the present study, the biosynthesis of TiO(2) nanoparticles (TiO(2) NPs) was achieved by a novel, biodegradable and convenient procedure using Aspergillus flavus as a reducing and capping agent. Research on new, simple, rapid, eco-friendly and cheaper methods has been initiated. TiO(2) NPs were characterized by FTIR, XRD, AFM, SEM and TEM studies. The X-ray diffraction showed the presence of increased amount of TiO(2) NPs which can state by the presence of peaks at rutile peaks at 100, 002, 100 and anatase forms at 101 respectively. SEM observations revealed that synthesized TiO(2) NPs were spherical, oval in shape; individual nanoparticles as well as a few aggregate having the size of 62-74 nm. AFM shows crystallization temperature was seen on the roughness of the surface of TiO(2). The Minimum inhibitory concentration value for the synthesized TiO(2) NPs was found to be 40 μg ml(-1) for Escherichia coli, which was corresponding to the value of well diffusion test. This is the first report on antimicrobial activity of fungus-mediated synthesized TiO(2) NPs, which was proved to be a good novel antibacterial material.

  8. The two-speed genomes of filamentous pathogens: waltz with plants.

    Science.gov (United States)

    Dong, Suomeng; Raffaele, Sylvain; Kamoun, Sophien

    2015-12-01

    Fungi and oomycetes include deep and diverse lineages of eukaryotic plant pathogens. The last 10 years have seen the sequencing of the genomes of a multitude of species of these so-called filamentous plant pathogens. Already, fundamental concepts have emerged. Filamentous plant pathogen genomes tend to harbor large repertoires of genes encoding virulence effectors that modulate host plant processes. Effector genes are not randomly distributed across the genomes but tend to be associated with compartments enriched in repetitive sequences and transposable elements. These findings have led to the 'two-speed genome' model in which filamentous pathogen genomes have a bipartite architecture with gene sparse, repeat rich compartments serving as a cradle for adaptive evolution. Here, we review this concept and discuss how plant pathogens are great model systems to study evolutionary adaptations at multiple time scales. We will also introduce the next phase of research on this topic.

  9. Diversity of Endophytic Fungi from Red Ginger (Zingiber officinale Rosc. Plant and Their Inhibitory Effect to Fusarium oxysporum Plant Pathogenic Fungi

    Directory of Open Access Journals (Sweden)

    SIHEGIKO KANAYA

    2013-09-01

    Full Text Available Indonesia has been known as a country with high medicinal plant diversity. One of the most common medicinal plant from Indonesia is red ginger (Zingiber officinale Rosc.. Nevertheless, limited studies of endophytic fungi associated with these medicinal plants are hitherto available. The objectives of this research were to study the diversity of endophytic fungi on red ginger and to analyze their potential as a source of antifungal agent. All parts of plant organs such as leaf, rhizome, root, and stem were subjected for isolation. Fungal identification was carried out by using a combination of morphological characteristic and molecular analysis of DNA sequence generated from ITS rDNA region. Thirty endophytic fungi were successfully isolated from leaf, rhizome, root, and stem of red ginger plant. Antagonistic activity was tested against Fusarium oxysporum, a pathogenic fungus on plants, using an antagonistic assay. Based on this approach, the fungi were assigned as Acremonium macroclavatum, Beltraniella sp., Cochliobolus geniculatus and its anamorphic stage Curvularia affinis, Fusarium solani, Glomerella cingulata, and its anamorphic stage Colletotrichum gloeosporoides, Lecanicillium kalimantanense, Myrothecium verrucaria, Neonectria punicea, Periconia macrospinosa, Rhizopycnis vagum, and Talaromyces assiutensis. R. vagum was found specifically on root whereas C. affinis, L. kalimantanense, and M. verrucaria were found on stem of red ginger plant. A. macroclavatum was found specifically in red ginger plant’s organ which located under the ground, whereas C. affinis was found from shoot or organ which located above the ground. The antagonistic activity of isolated endophytic fungi against F. oxysporum varied with the inhibition value range from 1.4 to 68.8%. C. affinis (JMbt7, F. solani (JMd14, and G. cingulata (JMr2 had significantly high antagonistic activity with the value above 65%; and R. vagum (JMa4 and C. geniculatus (JMbt9 had

  10. Growth substrates and caleosin-mediated functions affect conidial virulence in the insect pathogenic fungus Beauveria bassiana.

    Science.gov (United States)

    Ortiz-Urquiza, Almudena; Fan, Yanhua; Garrett, Timothy; Keyhani, Nemat O

    2016-11-01

    The entomopathogenic fungus, Beauveria bassiana, is a microbial biological control agent capable of infecting a wide range of insect hosts. Conidia (spores) initiate infection via adhesion, growth and penetration of the insect cuticle, whose outmost layer is rich in lipids. Conidial virulence was investigated in B. bassiana WT and caleosin mutants (ΔBbcal1), the latter a protein involved in lipid storage and turnover. Topical insect bioassays revealed that conidia of the WT strain showed up to 40-fold differences in LD50 values depending upon the growth substrate. The most virulent conidia were harvested from potato dextrose agar containing oleic acid, and the least potent were those derived from Sabouraud dextrose/yeast extract agar (SDAY). However, with the exception of conidia derived from SDAY and Czapek Dox agar, in which values were reduced, mean lethal times to kill (LT50) were essentially unaffected. In topical bioassays, the ΔBbcal1 mutant displayed LD50 values 5-40-fold higher than the WT depending upon the growth substrate, with ΔBbcal1 conidia derived from SDAY unable to effectively penetrate the host cuticle. The ΔBbcal1 mutant also showed concomitant dramatic increases in LT50 values from a mean of ~4.5 for WT to >8.5 days for the mutant. In contrast, intrahaemocoel injection bioassays that bypass cuticle penetration events revealed only minor effects on virulence for either WT or ΔBbcal1 conidia. These data highlight the importance of caleosin-dependent lipid mobilization and/or signalling in cuticle penetration events but suggest their dispensability for immune evasion and within-host growth.

  11. Cell surfaces in plant-microorganism interactions. I. A structural investigation of cell wall hydroxyproline-rich glycoproteins which accumulate in fungus-infected plants

    Energy Technology Data Exchange (ETDEWEB)

    Esquerre-Tugaye, M.T. (Universite Paul Sabatier, Toulouse, France); Lamport, D.T.A.

    1979-08-01

    Infection of muskmelon Cucumis melo seedlings by the fungus Colletotrichum lagenarium causes a 10-fold increase in the amount of cell wall hydroxyproline-rich glycoprotein. Evidence for this increase was provided by studying two specific markers of this glycoprotein, namely hydroxyproline and glycosylated serine. The lability of the O-glycosidic linkage of wall-bound glycosylated serine in the presence of hydrazine was used to determine the amount of serine which is glycosylated. A large increase in the hydroxyproline content of infected plants is shown, but the ratios of glycosylated serine to hydroxyproline are similar in healthy and infected plants. As far as these markers are concerned, the hydroxyproline-rich glycoproteins secreted into the wall as a result of the disease are similar to those of healthy plants. In addition, the extent of glycosylation of the wall serine, in both healthy and infected plants, decreases as the plant ages. Serine- and hydroxyproline-rich (glyco)peptides were also isolated after trypsinolysis of the wall. These (glyco)peptides include the galactosyl-containing pentapeptide, serine-hydroxyproline. This pentapeptide is characteristic of cell wall protein.

  12. Foliar endophytic fungi as potential protectors from pathogens in myrmecophytic Acacia plants

    OpenAIRE

    González-Teuber, M.; Jimenez-Aleman, G.; W Boland

    2014-01-01

    In defensive ant-plant interactions myrmecophytic plants express reduced chemical defense in their leaves to protect themselves from pathogens, and it seems that mutualistic partners are required to make up for this lack of defensive function. Previously, we reported that mutualistic ants confer plants of Acacia hindsii protection from pathogens, and that the protection is given by the ant-associated bacteria. Here, we examined whether foliar endophytic fungi may potentially act as a new part...

  13. Endophytic fungus decreases plant virus infections in meadow ryegrass (Lolium pratense)

    OpenAIRE

    Lehtonen, Päivi T; Helander, Marjo; Shahid A Siddiqui; Lehto, Kirsi; Saikkonen, Kari

    2006-01-01

    We studied the effects of fungal endophyte infection of meadow ryegrass (Lolium pratense=Festuca pratensis) on the frequency of the barley yellow dwarf virus (BYDV). The virus is transferred by aphids, which may be deterred by endophyte-origin alkaloids within the plant. In our experiment, we released viruliferous aphid vectors on endophyte-infected and endophyte-free plants in a common garden. The number of aphids and the percentage of BYDV infections were lower in endophyte-infected plants ...

  14. Arranging the bouquet of disease: floral traits and the transmission of plant and animal pathogens.

    Science.gov (United States)

    McArt, Scott H; Koch, Hauke; Irwin, Rebecca E; Adler, Lynn S

    2014-05-01

    Several floral microbes are known to be pathogenic to plants or floral visitors such as pollinators. Despite the ecological and economic importance of pathogens deposited in flowers, we often lack a basic understanding of how floral traits influence disease transmission. Here, we provide the first systematic review regarding how floral traits attract vectors (for plant pathogens) or hosts (for animal pathogens), mediate disease establishment and evolve under complex interactions with plant mutualists that can be vectors for microbial antagonists. Attraction of floral visitors is influenced by numerous phenological, morphological and chemical traits, and several plant pathogens manipulate floral traits to attract vectors. There is rapidly growing interest in how floral secondary compounds and antimicrobial enzymes influence disease establishment in plant hosts. Similarly, new research suggests that consumption of floral secondary compounds can reduce pathogen loads in animal pollinators. Given recent concerns about pollinator declines caused in part by pathogens, the role of floral traits in mediating pathogen transmission is a key area for further research. We conclude by discussing important implications of floral transmission of pathogens for agriculture, conservation and human health, suggesting promising avenues for future research in both basic and applied biology. © 2014 John Wiley & Sons Ltd/CNRS.

  15. Ecology of Fungus Gnats (Bradysia spp. in Greenhouse Production Systems Associated with Disease-Interactions and Alternative Management Strategies

    Directory of Open Access Journals (Sweden)

    Raymond A. Cloyd

    2015-04-01

    Full Text Available Fungus gnats (Bradysia spp. are major insect pests of greenhouse-grown horticultural crops mainly due to the direct feeding damage caused by the larvae, and the ability of larvae to transmit certain soil-borne plant pathogens. Currently, insecticides and biological control agents are being used successively to deal with fungus gnat populations in greenhouse production systems. However, these strategies may only be effective as long as greenhouse producers also implement alternative management strategies such as cultural, physical, and sanitation. This includes elimination of algae, and plant and growing medium debris; placing physical barriers onto the growing medium surface; and using materials that repel fungus gnat adults. This article describes the disease-interactions associated with fungus gnats and foliar and soil-borne diseases, and the alternative management strategies that should be considered by greenhouse producers in order to alleviate problems with fungus gnats in greenhouse production systems.

  16. Pathogenicity for onion and genetic diversity of isolates of the pathogenic fungus Colletotrichum gloeosporioides (Phyllachoraceae) from the State of Pernambuco, Brazil.

    Science.gov (United States)

    Nova, M X Vila; Borges, L R; de Sousa, A C B; Brasileiro, B T R V; Lima, E A L A; da Costa, A F; de Oliveira, N T

    2011-02-22

    Onion anthracnose, caused by Colletotrichum gloeosporioides, is one of the main diseases of onions in the State of Pernambuco. We examined the pathogenicity of 15 C. gloeosporioides strains and analyzed their genetic variability using RAPDs and internal transcribed spacers (ITS) of the rDNA region. Ten of the strains were obtained from substrates and hosts other than onion, including chayote (Sechium edule), guava (Psidium guajava), pomegranate (Punica granatum), water from the Capibaribe River, maracock (Passiflora sp), coconut (Cocus nucifera), surinam cherry (Eugenia uniflora), and marine soil; five isolates came from onions collected from four different regions of the State of Pernambuco and one region of the State of Amazonas. Pathogenicity tests were carried out using onion leaves and bulbs. All strains were capable of causing disease in leaves, causing a variable degree of lesions on the leaves; four strains caused the most severe damage. In the onion bulb tests, only three of the above strains caused lesions. Seven primers of arbitrary sequences were used in the RAPD analysis, generating polymorphic bands that allowed the separation of the strains into three distinct groups. The amplification products generated with the primers ITS1 and ITS4 also showed polymorphism when digested with three restriction enzymes, DraI, HaeIII and MspI. Only the latter two demonstrated genetic variations among the strains. These two types of molecular markers were able to differentiate the strain from the State of Amazonas from those of the State of Pernambuco. However, there was no relationship between groups of strains, based on molecular markers, and degree of pathogenicity for onion leaves and bulbs.

  17. The arable plant ecosystem as battleground for emergence of human pathogens

    Directory of Open Access Journals (Sweden)

    Leo eVan Overbeek

    2014-03-01

    Full Text Available Disease incidences related to Escherichia coli and Salmonella enterica infections by consumption of (fresh vegetables, sprouts and occasionally fruits made clear that these pathogens are not only transmitted to humans via the ‘classical’ routes of meat, eggs and dairy products, but also can be transmitted to humans via plants or products derived from plants. Nowadays, it is of major concern that these human pathogens, especially the ones belonging to the taxonomical family of Enterobacteriaceae, become adapted to environmental habitats without losing their virulence to humans. Adaptation to the plant environment would lead to longer persistence in plants, increasing their chances on transmission to humans via consumption of plant-derived food. One of the mechanisms of adaptation to the plant environment in human pathogens, proposed in this paper, is horizontal transfer of genes from different microbial communities present in the arable ecosystem, like the ones originating from soil, animal digestive track systems (manure, water and plants themselves. Genes that would confer better adaptation to the phytosphere might be genes involved in plant colonization, stress resistance and nutrient acquisition and utilization. Because human pathogenic enterics often were prone to genetic exchanges via phages and conjugative plasmids, it was postulated that these genetic elements may be hold key responsible for horizontal gene transfers between human pathogens and indigenous microbes in agroproduction systems. In analogy to zoonosis, we coin the term phytonosis for a human pathogen that is transmitted via plants and not exclusively via animals.

  18. Antifungal Activities of Extracts from Selected Lebanese Wild Plants against Plant Pathogenic Fungi

    Directory of Open Access Journals (Sweden)

    Y. Abou-Jawdah

    2004-12-01

    Full Text Available Extracts of nine plant species growing wild in Lebanon were tested for their efficacy against seven plant pathogenic fungi: Botrytis cinerea, Alternaria solani, Penicillium sp., Cladosporium sp., Fusarium oxysporum f. sp. melonis, Rhizoctonia solani and Sphaerotheca cucurbitae. Extracts of three of the plants, Origanum syriacum, Micromeria nervosa and Plumbago maritima, showed the highest levels of in vitro activity against spore germination and mycelial growth of the fungi tested. Inula viscosa showed high activity against spore germination but only moderate activity against mycelial growth. The other five plant species tested Calamintha origanifolia, Micromeria juliana, Ruta sp., Sideritis pullulans and Urginea maritima showed only moderate to low activity against these fungi. Preventive sprays with extracts of O. syriacum, M. nervosa, P. maritima and I. viscosa, applied at concentrations ranging between 4 and 8% to squash and cucumber seedlings, gave efficient protection against gray mold caused by B. cinerea and powdery mildew caused by S. cucurbitae. However, these extracts did not control green mold of citrus fruits caused by Penicillium sp. Thin layer chromatography revealed three inhibitory bands in extracts of O. syriacum, two in I. viscosa and only one in each of the other plants tested: M. nervosa, P. maritima, C. origanifolia and Ruta sp.

  19. Plant-mycorrhizal fungus co-occurrence network lacks substantial structure

    NARCIS (Netherlands)

    Encinas-Viso, Francisco; Alonso, David; Klironomos, John N.; Etienne, Rampal S.; Chang, Esther R.

    2016-01-01

    The interactions between plants and arbuscular mycorrhizal fungi (AMF) maintain a crucial link between macroscopic organisms and the soil microbial world. These interactions are of extreme importance for the diversity of plant communities and ecosystem functioning. Despite this importance, only rece

  20. Impact of vector dispersal and host-plant fidelity on the dissemination of an emerging plant pathogen.

    Directory of Open Access Journals (Sweden)

    Jes Johannesen

    Full Text Available Dissemination of vector-transmitted pathogens depend on the survival and dispersal of the vector and the vector's ability to transmit the pathogen, while the host range of vector and pathogen determine the breath of transmission possibilities. In this study, we address how the interaction between dispersal and plant fidelities of a pathogen (stolbur phytoplasma tuf-a and its vector (Hyalesthes obsoletus: Cixiidae affect the emergence of the pathogen. Using genetic markers, we analysed the geographic origin and range expansion of both organisms in Western Europe and, specifically, whether the pathogen's dissemination in the northern range is caused by resident vectors widening their host-plant use from field bindweed to stinging nettle, and subsequent host specialisation. We found evidence for common origins of pathogen and vector south of the European Alps. Genetic patterns in vector populations show signals of secondary range expansion in Western Europe leading to dissemination of tuf-a pathogens, which might be newly acquired and of hybrid origin. Hence, the emergence of stolbur tuf-a in the northern range was explained by secondary immigration of vectors carrying stinging nettle-specialised tuf-a, not by widening the host-plant spectrum of resident vectors with pathogen transmission from field bindweed to stinging nettle nor by primary co-migration from the resident vector's historical area of origin. The introduction of tuf-a to stinging nettle in the northern range was therefore independent of vector's host-plant specialisation but the rapid pathogen dissemination depended on the vector's host shift, whereas the general dissemination elsewhere was linked to plant specialisation of the pathogen but not of the vector.

  1. Colonization of Greek olive cultivars' root system by arbuscular mycorrhiza fungus: root morphology, growth, and mineral nutrition of olive plants

    Directory of Open Access Journals (Sweden)

    Theocharis Chatzistathis

    2013-06-01

    Full Text Available Rooted leafy cuttings of three Greek olive (Olea europaea L. cultivars (Koroneiki, Kothreiki and Chondrolia Chalkidikis were grown for six months in three soil types, in an experimental greenhouse, in order to investigate: i if their root system was colonized by arbuscular mycorrhiza fungus (AMF genus and, ii if genotypic differences concerning growth and mineral nutrition of olive plants existed. Gigaspora sp. colonized the root system of the three cultivars studied, while Glomus sp. colonized only the root system of 'Koroneiki'. Furthermore, in most cases root colonization by AMF differed among cultivars and soil types. The maximum root colonization, in all soils, was found in 'Chondrolia Chalkidikis'. In the three soils studied, the ratio shoot dry weight (SDW/ root dry weight (RDW was higher in 'Chondrolia Chalkidikis' than in the other two cultivars. Furthermore, root system morphology of the three olive cultivars was completely different, irrespectively of soil type. Leaf Mn, Fe, Zn, Ca, Mg, K and P concentrations, as well as total per plant nutrient content and nutrient use efficiency, differed among cultivars under the same soil conditions. These differences concerning root morphology, SDW/RDW, as well as nutrient uptake and use efficiency, could be possibly ascribed to the differential AMF colonization by Glomus sp. and Gigaspora sp.

  2. Screening of marine fungus from Nanji Island and activity of their metabolites against pathogenic Vibrio from Pseudosciaena crocea

    Institute of Scientific and Technical Information of China (English)

    ZHAO Shujiang; LI Shuping; LIU Huihui; ZHAO Qian; WANG Jieyou; YAN Maocang

    2012-01-01

    Seventy-eight marine fungal strains were isolated from sediment samples collected offthe coast of Nanji Island,Wenzhou,Zhejiang Province,China.Antibacterial screening using the agar disc method showed that 19 of the isolated strains could inhibit at least one pathogenic Vibrio from Pseudosciaena crocea.Subsequent screening confirmed that nine strains produced antibacterial metabolites that had activity against one or several types of pathogenic Vibrio.Strain N J0104 had the widest antimicrobial spectrum and strong activity,particularly against Vibrio parahaemolyticus-MM0810072.A preliminary study of NJ0104antibacterial metabolites demonstrated that they had thermal stability up to 80℃,ultraviolet stability up to 40 min and pH stability between 4.0-7.0.In addition,the antibacterial metabolites were readily soluble in butanol.To identify the specific strain,the ITS-5.8S rDNA regions of NJ0104 were PCR amplified and sequenced.Based on the combination of phenotypic and genotypic data,the strain was identified as Arthrinium sp.

  3. Exserohilum rostratum: characterization of a cross-kingdom pathogen of plants and humans.

    Directory of Open Access Journals (Sweden)

    Kalpana Sharma

    Full Text Available Pathogen host shifts represent a major source of new infectious diseases. There are several examples of cross-genus host jumps that have caused catastrophic epidemics in animal and plant species worldwide. Cross-kingdom jumps are rare, and are often associated with nosocomial infections. Here we provide an example of human-mediated cross-kingdom jumping of Exserohilum rostratum isolated from a patient who had received a corticosteroid injection and died of fungal meningitis in a Florida hospital in 2012. The clinical isolate of E. rostratum was compared with two plant pathogenic isolates of E. rostratum and an isolate of the closely related genus Bipolaris in terms of morphology, phylogeny, and pathogenicity on one C3 grass, Gulf annual rye grass (Lolium multiflorum, and two C4 grasses, Japanese stilt grass (Microstegium vimineum and bahia grass (Paspalum notatum. Colony growth and color, as well as conidia shape and size were the same for the clinical and plant isolates of E. rostratum, while these characteristics differed slightly for the Bipolaris sp. isolate. The plant pathogenic and clinical isolates of E. rostratum were indistinguishable based on morphology and ITS and 28S rDNA sequence analysis. The clinical isolate was as pathogenic to all grass species tested as the plant pathogenic strains that were originally isolated from plant hosts. The clinical isolate induced more severe symptoms on stilt grass than on rye grass, while this was the reverse for the plant isolates of E. rostratum. The phylogenetic similarity between the clinical and plant-associated E. rostratum isolates and the ability of the clinical isolate to infect plants suggests that a plant pathogenic strain of E. rostratum contaminated the corticosteroid injection fluid and was able to cause systemic disease in the affected patient. This is the first proof that a clinical isolate of E. rostratum is also an effective plant pathogen.

  4. The xylem as battleground for plant hosts and vascular wilt pathogens

    Directory of Open Access Journals (Sweden)

    Koste eYadeta

    2013-04-01

    Full Text Available Vascular wilts are among the most destructive plant diseases that occur in annual crops as well as in woody perennials. These diseases are generally caused by soil-borne bacteria, fungi and oomycetes that infect through the roots and enter the water-conducting xylem vessels where they proliferate and obstruct the transportation of water and minerals. As a consequence, leaves wilt and die, which may lead to impairment of the whole plant and eventually to death of the plant. Cultural, chemical and biological measures to control this group of plant pathogens are generally ineffective, and the most effective control strategy is the use of genetic resistance. Owing to the fact that vascular wilt pathogens live deep in the interior of their host plants, studies into the biology of vascular pathogens are complicated. However, to design novel strategies to combat vascular wilt diseases, understanding the (molecular biology of vascular pathogens and the molecular mechanisms underlying plant defense against these pathogens is crucial. In this review we discuss the current knowledge on interactions of vascular wilt pathogens with their host plants, with emphasis on host defense responses against this group of pathogens.

  5. A possible role of sexuality in the population structure of Diaporthe adunca, a pathogen of Plantago lanceolata

    NARCIS (Netherlands)

    Linders, E.G.A.

    1996-01-01

    In this study, the population structure of the fungal pathogen Diaporthe adunca on its perennial wild host plant Plantago lanceolata was analysed, together with the occurrence of the sexual stage of the fungus. The fungus overwinters on scapes infected in the previous year. In spring, it sporulates

  6. The development and endophytic nature of the fungus Heteroconium chaetospira.

    Science.gov (United States)

    Hashiba, Teruyoshi; Narisawa, Kazuhiko

    2005-11-15

    The root endophytic fungus Heteroconium chaetospira was isolated from roots of Chinese cabbage grown in field soil in Japan. This fungus penetrates through the outer epidermal cells of its host, passes into the inner cortex, and grows throughout the cortical cells, including those of the root tip region, without causing apparent pathogenic symptoms. There are no ultrastructural signs of host resistance responses. H. chaetospira has been recovered from 19 plant species in which there was no disruption of host growth. H. chaetospira has a symbiotic association with Chinese cabbage. The fungus provides nitrogen in exchange for carbon. These associations are beneficial for the inoculated plants, as demonstrated by increased growth rate. When used as a preinoculum, H. chaetospira suppresses the incidence of clubroot and Verticillium yellows when the test plant is post-inoculated with the causal agents of these diseases. H. chaetospira is an effective biocontrol agent against clubroot in Chinese cabbage at a low to moderate soil moisture range and a pathogen resting spore density of 10(5) resting spores per gram of soil in situ. Disease caused by Pseudomonas syringae pv. macricola and Alternaria brassicae on leaves can be suppressed by treatment with H. chaetospira. The fungus persists in the roots and induces systemic resistance to the foliar disease.

  7. Phenotypic variation in the plant pathogenic bacterium Acidovorax citrulli.

    Directory of Open Access Journals (Sweden)

    Ram Kumar Shrestha

    Full Text Available Acidovorax citrulli causes bacterial fruit blotch (BFB of cucurbits, a disease that threatens the cucurbit industry worldwide. Despite the economic importance of BFB, little is known about pathogenicity and fitness strategies of the bacterium. We have observed the phenomenon of phenotypic variation in A. citrulli. Here we report the characterization of phenotypic variants (PVs of two strains, M6 and 7a1, isolated from melon and watermelon, respectively. Phenotypic variation was observed following growth in rich medium, as well as upon isolation of bacteria from inoculated plants or exposure to several stresses, including heat, salt and acidic conditions. When grown on nutrient agar, all PV colonies possessed a translucent appearance, in contrast to parental strain colonies that were opaque. After 72 h, PV colonies were bigger than parental colonies, and had a fuzzy appearance relative to parental strain colonies that are relatively smooth. A. citrulli colonies are generally surrounded by haloes detectable by the naked eye. These haloes are formed by type IV pilus (T4P-mediated twitching motility that occurs at the edge of the colony. No twitching haloes could be detected around colonies of both M6 and 7a1 PVs, and microscopy observations confirmed that indeed the PVs did not perform twitching motility. In agreement with these results, transmission electron microscopy revealed that M6 and 7a1 PVs do not produce T4P under tested conditions. PVs also differed from their parental strain in swimming motility and biofilm formation, and interestingly, all assessed variants were less virulent than their corresponding parental strains in seed transmission assays. Slight alterations could be detected in some DNA fingerprinting profiles of 7a1 variants relative to the parental strain, while no differences at all could be seen among M6 variants and parental strain, suggesting that, at least in the latter, phenotypic variation is mediated by slight genetic

  8. The PacC transcription factor regulates secondary metabolite production and stress response, but has only minor effects on virulence in the insect pathogenic fungus Beauveria bassiana.

    Science.gov (United States)

    Luo, Zhibing; Ren, Hui; Mousa, Jarrod J; Rangel, Drauzio E N; Zhang, Yongjun; Bruner, Steven D; Keyhani, Nemat O

    2017-02-01

    The PacC transcription factor is an important component of the fungal ambient pH-responsive regulatory system. Loss of pacC in the insect pathogenic fungus Beauveria bassiana resulted in an alkaline pH-dependent decrease in growth and pH-dependent increased susceptibility to osmotic (salt, sorbitol) stress and SDS. Extreme susceptibility to Congo Red was noted irrespective of pH, and ΔBbpacC conidia showed subtle increases in UV susceptibility. The ΔBbPacC mutant showed a reduced ability to acidify media during growth due to failure to produce oxalic acid. The ΔBbPacC mutant also did not produce the insecticidal compound dipicolinic acid, however, production of a yellow-colored compound was noted. The compound, named bassianolone B, was purified and its structure determined. Despite defects in growth, stress resistance, and oxalate/insecticidal compound production, only a small decrease in virulence was seen for the ΔBbpacC strain in topical insect bioassays using larvae from the greater waxmoth, Galleria mellonella or adults of the beetle, Tenebrio molitor. However, slightly more pronounced decreases were seen in virulence via intrahemcoel injection assays (G. mellonella) and in assays using T. molitor larvae. These data suggest important roles for BbpacC in mediating growth at alkaline pH, regulating secondary metabolite production, and in targeting specific insect stages.

  9. Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

    Science.gov (United States)

    Adam, Mohamed; Heuer, Holger; Hallmann, Johannes

    2014-01-01

    The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

  10. Bacterial antagonists of fungal pathogens also control root-knot nematodes by induced systemic resistance of tomato plants.

    Directory of Open Access Journals (Sweden)

    Mohamed Adam

    Full Text Available The potential of bacterial antagonists of fungal pathogens to control the root-knot nematode Meloidogyne incognita was investigated under greenhouse conditions. Treatment of tomato seeds with several strains significantly reduced the numbers of galls and egg masses compared with the untreated control. Best performed Bacillus subtilis isolates Sb4-23, Mc5-Re2, and Mc2-Re2, which were further studied for their mode of action with regard to direct effects by bacterial metabolites or repellents, and plant mediated effects. Drenching of soil with culture supernatants significantly reduced the number of egg masses produced by M. incognita on tomato by up to 62% compared to the control without culture supernatant. Repellence of juveniles by the antagonists was shown in a linked twin-pot set-up, where a majority of juveniles penetrated roots on the side without inoculated antagonists. All tested biocontrol strains induced systemic resistance against M. incognita in tomato, as revealed in a split-root system where the bacteria and the nematodes were inoculated at spatially separated roots of the same plant. This reduced the production of egg masses by up to 51%, while inoculation of bacteria and nematodes in the same pot had only a minor additive effect on suppression of M. incognita compared to induced systemic resistance alone. Therefore, the plant mediated effect was the major reason for antagonism rather than direct mechanisms. In conclusion, the bacteria known for their antagonistic potential against fungal pathogens also suppressed M. incognita. Such "multi-purpose" bacteria might provide new options for control strategies, especially with respect to nematode-fungus disease complexes that cause synergistic yield losses.

  11. Biocide plants as a sustainable tool for the control of pests and pathogens in vegetable cropping systems

    Directory of Open Access Journals (Sweden)

    Trifone D'Addabbo

    2014-11-01

    Full Text Available Synthetic pesticides have played a major role in crop protection related to the intensification of agricultural systems. In the recent years, environmental side effects and health concerns raised by an indiscriminate use have led the EU to the ban of many synthetic pesticides. As a result of this drastic revision, currently there is a strong need for new and alternative pest control methods. An interesting source of biorational pesticides may be represented by the biocidal compounds naturally occurring in plants as products of the secondary metabolism. Groups of plant secondary metabolites most promising for the development of pesticidal formulations are glucosinolates, saponins, and more generally terpenoid phytoconstituents, such as essential oil and their constituents. Glucosinolates are thioglucosidic secondary metabolites occurring mainly in the Brassicaceae and, at a less extent, in Capparidaceae families. The incorporation of glucosinolate- containing plant material into the soil results in degradation products highly toxic to soilborne pest, pathogens and weeds. This practice, known as biofumigation, may be considered as an ecological alternative to soil toxic fumigants. Plant-derived saponins are triterpene glycosides present in top and root tissues of plant species of the families Leguminosae, Alliaceae, Asteraceae, Polygalaceae and Agavaceae. Saponins and saponin-rich plant materials have been also reported for a biocidal activity on phytoparasites and soilborne plant pathogens. Essential oils are volatile, natural, heterogeneous mixtures of single substances, mainly terpenes and phenolics, formed as secondary metabolites by aromatic plants belonging to several botanical families. Among terpenes, limonoid triterpenes have been demonstrated to possess interesting insecticidal, nematicidal and antifungal properties. Occurrence of these compounds is mainly limited to Meliaceae and Rutaceae. Alkaloids, phenolics, cyanogenic glucosides

  12. Combating Pathogenic Microorganisms Using Plant-Derived Antimicrobials: A Minireview of the Mechanistic Basis

    Directory of Open Access Journals (Sweden)

    Abhinav Upadhyay

    2014-01-01

    Full Text Available The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plant-derived antimicrobials (PDAs as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed.

  13. Frontiers for research on the ecology of plant-pathogenic bacteria: fundamentals for sustainability: Challenges in Bacterial Molecular Plant Pathology.

    Science.gov (United States)

    Morris, Cindy E; Barny, Marie-Anne; Berge, Odile; Kinkel, Linda L; Lacroix, Christelle

    2017-02-01

    Methods to ensure the health of crops owe their efficacy to the extent to which we understand the ecology and biology of environmental microorganisms and the conditions under which their interactions with plants lead to losses in crop quality or yield. However, in the pursuit of this knowledge, notions of the ecology of plant-pathogenic microorganisms have been reduced to a plant-centric and agro-centric focus. With increasing global change, i.e. changes that encompass not only climate, but also biodiversity, the geographical distribution of biomes, human demographic and socio-economic adaptations and land use, new plant health problems will emerge via a range of processes influenced by these changes. Hence, knowledge of the ecology of plant pathogens will play an increasingly important role in the anticipation and response to disease emergence. Here, we present our opinion on the major challenges facing the study of the ecology of plant-pathogenic bacteria. We argue that the discovery of markedly novel insights into the ecology of plant-pathogenic bacteria is most likely to happen within a framework of more extensive scales of space, time and biotic interactions than those that currently guide much of the research on these bacteria. This will set a context that is more propitious for the discovery of unsuspected drivers of the survival and diversification of plant-pathogenic bacteria and of the factors most critical for disease emergence, and will set the foundation for new approaches to the sustainable management of plant health. We describe the contextual background of, justification for and specific research questions with regard to the following challenges: Development of terminology to describe plant-bacterial relationships in terms of bacterial fitness. Definition of the full scope of the environments in which plant-pathogenic bacteria reside or survive. Delineation of pertinent phylogenetic contours of plant-pathogenic bacteria and naming of strains

  14. Advances on plant-pathogen interactions from molecular toward systems biology perspectives.

    Science.gov (United States)

    Peyraud, Rémi; Dubiella, Ullrich; Barbacci, Adelin; Genin, Stéphane; Raffaele, Sylvain; Roby, Dominique

    2016-11-21

    In the past 2 decades, progress in molecular analyses of the plant immune system has revealed key elements of a complex response network. Current paradigms depict the interaction of pathogen-secreted molecules with host target molecules leading to the activation of multiple plant response pathways. Further research will be required to fully understand how these responses are integrated in space and time, and exploit this knowledge in agriculture. In this review, we highlight systems biology as a promising approach to reveal properties of molecular plant-pathogen interactions and predict the outcome of such interactions. We first illustrate a few key concepts in plant immunity with a network and systems biology perspective. Next, we present some basic principles of systems biology and show how they allow integrating multiomics data and predict cell phenotypes. We identify challenges for systems biology of plant-pathogen interactions, including the reconstruction of multiscale mechanistic models and the connection of host and pathogen models. Finally, we outline studies on resistance durability through the robustness of immune system networks, the identification of trade-offs between immunity and growth and in silico plant-pathogen co-evolution as exciting perspectives in the field. We conclude that the development of sophisticated models of plant diseases incorporating plant, pathogen and climate properties represent a major challenge for agriculture in the future.

  15. Calpains are involved in asexual and sexual development, cell wall integrity and pathogenicity of the rice blast fungus.

    Science.gov (United States)

    Liu, Xiao-Hong; Ning, Guo-Ao; Huang, Lu-Yao; Zhao, Ya-Hui; Dong, Bo; Lu, Jian-Ping; Lin, Fu-Cheng

    2016-08-09

    Calpains are ubiquitous and well-conserved proteins that belong to the calcium-dependent, non-lysosomal cysteine protease family. In this study, 8 putative calpains were identified using Pfam domain analysis and BlastP searches in M. oryzae. Three single gene deletion mutants (ΔMocapn7, ΔMocapn9 and ΔMocapn14) and two double gene deletion mutants (ΔMocapn4ΔMocapn7 and ΔMocapn9ΔMocapn7) were obtained using the high-throughput gene knockout system. The calpain disruption mutants showed defects in colony characteristics, conidiation, sexual reproduction and cell wall integrity. The mycelia of the ΔMocapn7, ΔMocapn4ΔMocapn7 and ΔMocapn9ΔMocapn7 mutants showed reduced pathogenicity on rice and barley.

  16. Biocontrol of the toxigenic plant pathogen Fusarium culmorum by soil fauna in an agroecosystem.

    Science.gov (United States)

    Meyer-Wolfarth, Friederike; Schrader, Stefan; Oldenburg, Elisabeth; Weinert, Joachim; Brunotte, Joachim

    2017-08-01

    L. terrestris revealed a considerable potential as an effective biocontrol agent contributing to a sustainable control of a Fusarium plant pathogen in wheat straw, thus reducing the infection risk for specific plant diseases in arable fields.

  17. A critical role of autophagy in plant resistance to necrotrophic fungal pathogens.

    Science.gov (United States)

    Lai, Zhibing; Wang, Fei; Zheng, Zuyu; Fan, Baofang; Chen, Zhixiang

    2011-06-01

    Autophagy is a pathway for degradation of cytoplasmic components. In plants, autophagy plays an important role in nutrient recycling during nitrogen or carbon starvation, and in responses to abiotic stress. Autophagy also regulates age- and immunity-related programmed cell death, which is important in plant defense against biotrophic pathogens. Here we show that autophagy plays a critical role in plant resistance to necrotrophic pathogens. ATG18a, a critical autophagy protein in Arabidopsis, interacts with WRKY33, a transcription factor that is required for resistance to necrotrophic pathogens. Expression of autophagy genes and formation of autophagosomes are induced in Arabidopsis by the necrotrophic fungal pathogen Botrytis cinerea. Induction of ATG18a and autophagy by B. cinerea was compromised in the wrky33 mutant, which is highly susceptible to necrotrophic pathogens. Arabidopsis mutants defective in autophagy exhibit enhanced susceptibility to the necrotrophic fungal pathogens B. cinerea and Alternaria brassicicola based on increased pathogen growth in the mutants. The hypersusceptibility of the autophagy mutants was associated with reduced expression of the jasmonate-regulated PFD1.2 gene, accelerated development of senescence-like chlorotic symptoms, and increased protein degradation in infected plant tissues. These results strongly suggest that autophagy cooperates with jasmonate- and WRKY33-mediated signaling pathways in the regulation of plant defense responses to necrotrophic pathogens.

  18. Production of Plant Growth-Regulating Substances by the Vesicular-Arbuscular Mycorrhizal Fungus Glomus mosseae

    OpenAIRE

    Barea, José M.; Azcón-Aguilar, Concepción

    1982-01-01

    Glomus mosseae, a representative species of Endogonaceae (Phycomycetes) able to form vesicular-arbuscular mycorrhiza, was investigated for phytohormone production. Spores of G. mosseae were axenically germinated in water, and the resultant mycelial growth was assayed by standard procedures for extracting plant hormones from microbial cultures. Paper partition chromatography and specific bioassays were used to separate and identify plant growth-regulating substances. The microorganism synthesi...

  19. Genome of an arbuscular mycorrhizal fungus provides insight into the oldest plant symbiosis

    OpenAIRE

    2013-01-01

    The arbuscular mycorrhizal symbiosis between fungi of the Glomeromycota phylum and plants involves more than two-thirds of all known plant species, including important crop species. This mutualistic symbiosis, involving one of the oldest fungal lineages, is arguably the most ecologically and agriculturally important symbiosis in terrestrial ecosystems. The Glomeromycota are unique in that their spores and coenocytic hyphae contain hundreds of nuclei in a common cytoplasm, which raises importa...

  20. Restoration of camptothecine production in attenuated endophytic fungus on re-inoculation into host plant and treatment with DNA methyltransferase inhibitor.

    Science.gov (United States)

    Vasanthakumari, M M; Jadhav, S S; Sachin, Naik; Vinod, G; Shweta, Singh; Manjunatha, B L; Kumara, P Mohana; Ravikanth, G; Nataraja, Karaba N; Uma Shaanker, R

    2015-10-01

    Fungal endophytes inhabit living tissues of plants without any apparent symptoms and in many cases are known to produce secondary metabolites similar to those produced by their respective host plants. However on sub-culture, the endophytic fungi gradually attenuate their ability to produce the metabolites. Attenuation has been a major constraint in realizing the potential of endophytic fungi as an alternative source of plant secondary metabolites. In this study, we report attempts to restore camptothecine (CPT) production in attenuated endophytic fungi isolated from CPT producing plants, Nothapodytes nimmoniana and Miquelia dentata when they are passed through their host plant or plants that produce CPT and when treated with a DNA methyl transferase inhibitor. Attenuated endophytic fungi that traversed through their host tissue or plants capable of synthesizing CPT, produced significantly higher CPT compared to the attenuated fungi. Attenuated fungus cultured in the presence of 5-azacytidine, a DNA methyltransferase inhibitor, had an enhanced CPT content compared to untreated attenuated fungus. These results indicate that the attenuation of CPT production in endophytic fungi could in principle be reversed by eliciting some signals from plant tissue, most likely that which prevents the methylation or silencing of the genes responsible for CPT biosynthesis.

  1. Functional analysis of the kinome of the wheat scab fungus Fusarium graminearum

    Science.gov (United States)

    As in many other eukaryotes, protein kinases play major regulatory roles in filamentous fungi. Although the genomes of numerous plant pathogenic fungi have been sequenced, systematic characterization of their kinomes has not been reported. The wheat scab fungus Fusarium graminearum has 116 putative ...

  2. Draft Genome Sequence of Sorghum Grain Mold Fungus Epicoccum sorghinum, a Producer of Tenuazonic Acid

    Science.gov (United States)

    Oliveira, Rodrigo C.; Davenport, Karen W.; Hovde, Blake; Silva, Danielle; Chain, Patrick S. G.; Correa, Benedito

    2017-01-01

    ABSTRACT The facultative plant pathogen Epicoccum sorghinum is associated with grain mold of sorghum and produces the mycotoxin tenuazonic acid. This fungus can have serious economic impact on sorghum production. Here, we report the draft genome sequence of E. sorghinum (USPMTOX48). PMID:28126937

  3. Controlling hormone signaling is a plant and pathogen challenge for growth and survival.

    Science.gov (United States)

    López, Miguel Angel; Bannenberg, Gerard; Castresana, Carmen

    2008-08-01

    Plants and pathogens have continuously confronted each other during evolution in a battle for growth and survival. New advances in the field have provided fascinating insights into the mechanisms that have co-evolved to gain a competitive advantage in this battle. When plants encounter an invading pathogen, not only responses signaled by defense hormones are activated to restrict pathogen invasion, but also the modulation of additional hormone pathways is required to serve other purposes, which are equally important for plant survival, such as re-allocation of resources, control of cell death, regulation of water stress, and modification of plant architecture. Notably, pathogens can counteract both types of responses as a strategy to enhance virulence. Pathogens regulate production and signaling responses of plant hormones during infection, and also produce phytohormones themselves to modulate plant responses. These results indicate that hormone signaling is a relevant component in plant-pathogen interactions, and that the ability to dictate hormonal directionality is critical to the outcome of an interaction.

  4. Commonalities and differences of T3SSs in rhizobia and plant pathogenic bacteria.

    Science.gov (United States)

    Tampakaki, Anastasia P

    2014-01-01

    Plant pathogenic bacteria and rhizobia infect higher plants albeit the interactions with their hosts are principally distinct and lead to completely different phenotypic outcomes, either pathogenic or mutualistic, respectively. Bacterial protein delivery to plant host plays an essential role in determining the phenotypic outcome of plant-bacteria interactions. The involvement of type III secretion systems (T3SSs) in mediating animal- and plant-pathogen interactions was discovered in the mid-80's and is now recognized as a multiprotein nanomachine dedicated to trans-kingdom movement of effector proteins. The discovery of T3SS in bacteria with symbiotic lifestyles broadened its role beyond virulence. In most T3SS-positive bacterial pathogens, virulence is largely dependent on functional T3SSs, while in rhizobia the system is dispensable for nodulation and can affect positively or negatively the mutualistic associations with their hosts. This review focuses on recent comparative genome analyses in plant pathogens and rhizobia that uncovered similarities and variations among T3SSs in their genetic organization, regulatory networks and type III secreted proteins and discusses the evolutionary adaptations of T3SSs and type III secreted proteins that might account for the distinguishable phenotypes and host range characteristics of plant pathogens and symbionts.

  5. Green synthesis of highly stabilized nanocrystalline silver particles by a non-pathogenic and agriculturally important fungus T. asperellum

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, P; Mukherjee, P K; Kale, S P [Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Roy, M; Mandal, B P; Tyagi, A K [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dey, G K [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ghatak, J [Institute of Physics, Bhubaneswar 751005 (India)], E-mail: sharadkale@gmail.com

    2008-02-20

    A controlled and up-scalable biosynthetic route to nanocrystalline silver particles with well-defined morphology using cell-free aqueous filtrate of a non-pathogenic and commercially viable biocontrol agent Trichoderma asperellum is being reported for the first time. A transparent solution of the cell-free filtrate of Trichoderma asperellum containing 1 mM AgNO{sub 3} turns progressively dark brown within 5 d of incubation at 25 deg. C. The kinetics of the reaction was studied using UV-vis spectroscopy. An intense surface plasmon resonance band at {approx}410 nm in the UV-vis spectrum clearly reveals the formation of silver nanoparticles. The size of the silver particles using TEM and XRD studies is found to be in the range 13-18 nm. These nanoparticles are found to be highly stable and even after prolonged storage for over 6 months they do not show significant aggregation. A plausible mechanism behind the formation of silver nanoparticles and their stabilization via capping has been investigated using FTIR and surface-enhanced resonance Raman spectroscopy.

  6. Widespread Occurrence of Diverse Human Pathogenic Types of the Fungus Fusarium Detected in Plumbing Drains ▿ †

    Science.gov (United States)

    Short, Dylan P. G.; O'Donnell, Kerry; Zhang, Ning; Juba, Jean H.; Geiser, David M.

    2011-01-01

    It has been proposed that plumbing systems might serve as a significant environmental reservoir of human-pathogenic isolates of Fusarium. We tested this hypothesis by performing the first extensive multilocus sequence typing (MLST) survey of plumbing drain-associated Fusarium isolates and comparing the diversity observed to the known diversity of clinical Fusarium isolates. We sampled 471 drains, mostly in bathroom sinks, from 131 buildings in the United States using a swabbing method. We found that 66% of sinks and 80% of buildings surveyed yielded at least one Fusarium culture. A total of 297 isolates of Fusarium collected were subjected to MLST to identify the phylogenetic species and sequence types (STs) of these isolates. Our survey revealed that the six most common STs in sinks were identical to the six most frequently associated with human infections. We speculate that the most prevalent STs, by virtue of their ability to form and grow in biofilms, are well adapted to plumbing systems. Six major Fusarium STs were frequently isolated from plumbing drains within a broad geographic area and were identical to STs frequently associated with human infections. PMID:21976755

  7. Insertional mutagenesis in the vascular wilt pathogen Verticillium dahliae

    NARCIS (Netherlands)

    Santhanam, P.

    2014-01-01

    Vascular wilt diseases caused by soil-borne pathogens are among the most devastating plant diseases worldwide. The ascomycete fungus Verticillium dahliae causes vascular wilt diseases in hundreds of dicotyledonous plant species, including important crops such as eggplant, lettuce, olive, spinach

  8. Plant biomass degrading ability of the coprophilic ascomycete fungus Podospora anserina.

    Science.gov (United States)

    Couturier, Marie; Tangthirasunun, Narumon; Ning, Xie; Brun, Sylvain; Gautier, Valérie; Bennati-Granier, Chloé; Silar, Philippe; Berrin, Jean-Guy

    2016-01-01

    The degradation of plant biomass is a major challenge towards the production of bio-based compounds and materials. As key lignocellulolytic enzyme producers, filamentous fungi represent a promising reservoir to tackle this challenge. Among them, the coprophilous ascomycete Podospora anserina has been used as a model organism to study various biological mechanisms because its genetics are well understood and controlled. In 2008, the sequencing of its genome revealed a great diversity of enzymes targeting plant carbohydrates and lignin. Since then, a large array of lignocellulose-acting enzymes has been characterized and genetic analyses have enabled the understanding of P. anserina metabolism and development on plant biomass. Overall, these research efforts shed light on P. anserina strategy to unlock recalcitrant lignocellulose deconstruction.

  9. Method of inhibiting plant virus pathogen infections by crispr/cas9-mediated interference

    KAUST Repository

    Mahfouz, Magdy Mahmoud

    2016-11-24

    A genetically modified tobacco plant or tomato plant resistant to at least one pathogenic geminiviridae virus species is provided. The plant comprises a heterologous CRISPR/Cas9 system and at least one heterologous nucleotide sequence that is capable of hybridizing to a nucleotide sequence of the pathogenic virus and that directs inactivation of the pathogenic virus species or plurality of viral species by the CRISPR/Cas9 system. The heterologous nucleotide sequence can be complementary to, but not limited to an Intergenic Region (IR) of the Tomato Yellow Leaf Curl Virus (TYLCV), Further provided are methods of generating a genetically modified plant that is resistant to a virus pathogen by a heterologous CRISPR/Cas9 system and expression of a gRNA specifically targeting the virus.

  10. Lifestyle transitions in plant pathogenic Colletotrichum fungi deciphered by genome and transcriptome analyses

    NARCIS (Netherlands)

    O'Connell, R.J.; Thon, M.R.; Hacquard, S.; Amyotte, S.G.; Kleemann, J.; Torres, M.F.; Damm, U.; Buiate, E.A.; Epstein, L.; Alkan, N.; Altmuller, J.; Alvarado-Balderrama, L.; Bauser, C.A.; Becker, C.; Birren, B.W.; Chen, Z.; Choi, J.; Crouch, J.A.; Duvick, J.P.; Farman, M.A.; Gan, P.; Heiman, D.; Henrissat, B.; Howard, R.J.; Kabbage, M.; Koch, C.; Kracher, B.; Kubo, Y.; Law, A.D.; Lebrun, M.-H.; Lee, Y.-H.; Miyara, I.; Moore, N.; Neumann, U.; Nordstrom, K.; Panaccione, D.G.; Panstruga, R.; Place, M.; Proctor, R.H.; Prusky, D.; Rech, G.; Reinhardt, R.; Rollins, J.A.; Rounsley, S.; Schardl, C.L.; Schwartz, D.C.; Shenoy, N.; Shirasu, K.; Sikhakolli, U.R.; Stuber, K.; Sukno, S.A.; Sweigard, J.A.; Takano, Y.; Takahara, H.; Trail, F.; Does, H.C.; Voll, L.M.; Will, I.; Young, S.; Zeng, Q.; Zhang, Jingze; Zhou, S.; Dickman, M.B.; Schulze-Lefert, P.; Verloren van Themaat, E.; Ma, L.-J.; Vaillancourt, L.J.

    2012-01-01

    Colletotrichum species are fungal pathogens that devastate crop plants worldwide. Host infection involves the differentiation of specialized cell types that are associated with penetration, growth inside living host cells (biotrophy) and tissue destruction (necrotrophy). We report here genome and

  11. Lifestyle transitions in plant pathogenic Colletotrichum fungi deciphered by genome and transcriptome analyses

    NARCIS (Netherlands)

    O'Connell, R.J.; Thon, M.R.; Hacquard, S.; Amyotte, S.G.; Kleemann, J.; Torres, M.F.; Damm, U.; Buiate, E.A.; Epstein, L.; Alkan, N.; Altmuller, J.; Alvarado-Balderrama, L.; Bauser, C.A.; Becker, C.; Birren, B.W.; Chen, Z.; Choi, J.; Crouch, J.A.; Duvick, J.P.; Farman, M.A.; Gan, P.; Heiman, D.; Henrissat, B.; Howard, R.J.; Kabbage, M.; Koch, C.; Kracher, B.; Kubo, Y.; Law, A.D.; Lebrun, M.-H.; Lee, Y.-H.; Miyara, I.; Moore, N.; Neumann, U.; Nordstrom, K.; Panaccione, D.G.; Panstruga, R.; Place, M.; Proctor, R.H.; Prusky, D.; Rech, G.; Reinhardt, R.; Rollins, J.A.; Rounsley, S.; Schardl, C.L.; Schwartz, D.C.; Shenoy, N.; Shirasu, K.; Sikhakolli, U.R.; Stuber, K.; Sukno, S.A.; Sweigard, J.A.; Takano, Y.; Takahara, H.; Trail, F.; Does, H.C.; Voll, L.M.; Will, I.; Young, S.; Zeng, Q.; Zhang, Jingze; Zhou, S.; Dickman, M.B.; Schulze-Lefert, P.; Verloren van Themaat, E.; Ma, L.-J.; Vaillancourt, L.J.

    2012-01-01

    Colletotrichum species are fungal pathogens that devastate crop plants worldwide. Host infection involves the differentiation of specialized cell types that are associated with penetration, growth inside living host cells (biotrophy) and tissue destruction (necrotrophy). We report here genome and tr

  12. A domain-centric analysis of oomycete plant pathogen genomes reveals unique protein organization

    NARCIS (Netherlands)

    Seidl, M.F.; Ackerveken, van den G.; Govers, F.; Snel, B.

    2011-01-01

    Oomycetes comprise a diverse group of organisms that morphologically resemble fungi but belong to the stramenopile lineage within the supergroup of chromalveolates. Recent studies have shown that plant pathogenic oomycetes have expanded gene families that are possibly linked to their pathogenic life

  13. Effectors as Tools in Disease Resistance Breeding Against Biotrophic, Hemibiotrophic, and Necrotrophic Plant Pathogens

    NARCIS (Netherlands)

    Vleeshouwers, V.G.A.A.; Oliver, R.P.

    2014-01-01

    One of most important challenges in plant breeding is improving resistance to the plethora of pathogens that threaten our crops. The ever-growing world population, changing pathogen populations, and fungicide resistance issues have increased the urgency of this task. In addition to a vital inflow of

  14. How filamentous pathogens co-opt plants; the ins and outs of eukaryotic effectors

    Science.gov (United States)

    Research on effectors secreted by pathogens during host attack has dominated the field of molecular plant-microbe interactions over recent years. Functional analysis of type III secreted effectors that are injected by pathogenic bacteria into host cells has significantly advanced the field and demon...

  15. Biosynthesis of archetypal plant self-defensive oxylipins by an endophytic fungus residing in mangrove embryos.

    Science.gov (United States)

    Ding, Ling; Peschel, Gundela; Hertweck, Christian

    2012-12-21

    A tree's travel companion: a fungal endophyte (Fusarium incarnatum) isolated from a viviparous propagule (embryo) of a mangrove tree produces typical plant defense oxylipins. Stable-isotope labeling experiments revealed that the endophyte biosynthesizes coriolic acid, didehydrocoriolic acid, and an epoxy fatty acid derived from linoleic acid by a process involving Δ(15)-desaturation and 13-lipoxygenation.

  16. Multi-omics approach identifies molecular mechanisms of plant-fungus mycorrhizal interaction

    Directory of Open Access Journals (Sweden)

    Peter E Larsen

    2016-01-01

    Full Text Available In mycorrhizal symbiosis, plant roots form close, mutually beneficial interactions with soil fungi. Before this mycorrhizal interaction can be established however, plant roots must be capable of detecting potential beneficial fungal partners and initiating the gene expression patterns necessary to begin symbiosis. To predict a plant root – mycorrhizal fungi sensor systems, we analyzed in vitro experiments of Populus tremuloides (aspen tree and Laccaria bicolor (mycorrhizal fungi interaction and leveraged over 200 previously published transcriptomic experimental data sets, 159 experimentally validated plant transcription factor binding motifs, and more than 120-thousand experimentally validated protein-protein interactions to generate models of pre-mycorrhizal sensor systems in aspen root. These sensor mechanisms link extracellular signaling molecules with gene regulation through a network comprised of membrane receptors, signal cascade proteins, transcription factors, and transcription factor biding DNA motifs. Modeling predicted four pre-mycorrhizal sensor complexes in aspen that interact with fifteen transcription factors to regulate the expression of 1184 genes in response to extracellular signals synthesized by Laccaria. Predicted extracellular signaling molecules include common signaling molecules such as phenylpropanoids, salicylate, and, jasmonic acid. This multi-omic computational modeling approach for predicting the complex sensory networks yielded specific, testable biological hypotheses for mycorrhizal interaction signaling compounds, sensor complexes, and mechanisms of gene regulation.

  17. Potential of the Endophytic Fungus Phialocephala fortinii Rac56 Found in Rhodiola Plants to Produce Salidroside and p-Tyrosol

    Directory of Open Access Journals (Sweden)

    Jinlong Cui

    2016-04-01

    Full Text Available 2-(4-Hydroxyphenylehyl-β-d-glucopyranoside (salidroside and 4-(2-hydroxyethylphenol (p-tyrosol are famous food and medicine additives originally derived from alpine Rhodiola plants. Salidroside or p-tyrosol production by the endophytic fungus Rac56 (Phialocephala fortinii was confirmed by UPLC/Q-TOF-MS and 1H-NMR. The fermentation conditions were optimized by orthogonal design using data processing system software. The broth fermentation results showed that salidroside and p-tyrosol extraction yields from Rac56 were stable and reached 1.729 ± 0.06 mg and 1.990 ± 0.05 mg per mL of culture medium, respectively. The optimal conditions for salidroside and p-tyrosol production in fermentation culture of Rac56 were determined to be 25 °C, pH values of 7 and 5, Czapek-Dox culture medium volumes of 150 mL and 50 mL in 250 mL flasks, rotation speeds of 100× g and 200× g, and fermentation durations of 7 and 15 days, respectively. Under these optimal conditions, stable yields of 2.339 ± 0.1093 mg and 2.002 ± 0.0009 mg per mL of culture medium of salidroside and p-tyrosol, respectively, were obtained, indicating that the P. fortinii Rac56 strain is a promising source of these compounds.

  18. Potential of the Endophytic Fungus Phialocephala fortinii Rac56 Found in Rhodiola Plants to Produce Salidroside and p-Tyrosol.

    Science.gov (United States)

    Cui, Jinlong; Guo, Tingting; Chao, Jianbin; Wang, Mengliang; Wang, Junhong

    2016-04-16

    2-(4-Hydroxyphenyl)ehyl-β-D-glucopyranoside (salidroside) and 4-(2-hydroxyethyl)phenol (p-tyrosol) are famous food and medicine additives originally derived from alpine Rhodiola plants. Salidroside or p-tyrosol production by the endophytic fungus Rac56 (Phialocephala fortinii) was confirmed by UPLC/Q-TOF-MS and ¹H-NMR. The fermentation conditions were optimized by orthogonal design using data processing system software. The broth fermentation results showed that salidroside and p-tyrosol extraction yields from Rac56 were stable and reached 1.729 ± 0.06 mg and 1.990 ± 0.05 mg per mL of culture medium, respectively. The optimal conditions for salidroside and p-tyrosol production in fermentation culture of Rac56 were determined to be 25 °C, pH values of 7 and 5, Czapek-Dox culture medium volumes of 150 mL and 50 mL in 250 mL flasks, rotation speeds of 100× g and 200× g, and fermentation durations of 7 and 15 days, respectively. Under these optimal conditions, stable yields of 2.339 ± 0.1093 mg and 2.002 ± 0.0009 mg per mL of culture medium of salidroside and p-tyrosol, respectively, were obtained, indicating that the P. fortinii Rac56 strain is a promising source of these compounds.

  19. [Production of inhibiting plant growth and development hormones by pathogenic for legumes Pseudomonas genus bacteria].

    Science.gov (United States)

    Dankevich, L A

    2013-01-01

    It has been studied the ability of pathogenic for legumes pathovars of Pseudomonas genus to produce ethylene and abscisic acid in vitro. A direct correlation between the level of ethylene production by agent of bacterial pea burn--Pseudomonas syringae pv. pisi and level of its aggressiveness for plants has been found. It is shown that the amount of abscisic acid synthesized by pathogenic for legumes Pseudomonas genus bacteria correlates with their aggressiveness for plants.

  20. Deciphering plant-pathogen communication: fresh perspectives for molecular resistance breeding.

    Science.gov (United States)

    Hammond-Kosack, Kim E; Parker, Jane E

    2003-04-01

    Activation of local and systemic plant defences in response to pathogen attack involves dramatic cellular reprogramming. Over the past 10 years many novel genes, proteins and molecules have been discovered as a result of investigating plant-pathogen interactions. Most attempts to harness this knowledge to engineer improved disease resistance in crops have failed. Although gene efficacy in transgenic plants has often been good, commercial exploitation has not been possible because of the detrimental effects on plant growth, development and crop yield. Biotechnology approaches have now shifted emphasis towards marker-assisted breeding and the construction of vectors containing highly regulated transgenes that confer resistance in several distinct ways.

  1. bryophyte extracts with activity against plant pathogenic fungi

    African Journals Online (AJOL)

    Preferred Customer

    evidenced on treated plants at 4 hours before the inoculation. However, plants treated by the same ... posing of toxicity dangers to the society in Western. Ethiopia have resulted in ...... of extinction due to deforestation and habitat degradation.

  2. Finished Genome of the Fungal Wheat Pathogen Mycosphaerella graminicola Reveals Dispensome Structure, Chromosome Plasticity, and Stealth Pathogenesis

    NARCIS (Netherlands)

    Goodwin, S.B.; Ben M'Barek, S.; Dhillon, B.; Wittenberg, A.H.J.; Crane, C.F.; Hane, J.K.; Foster, A.J.; van der Lee, T.A.J.; Grimwood, J.; Aerts, A.; Antoniw, J.; Bailey, A.; Bluhm, B.; Bowler, J.M.; Bristow, J.; van der Burgt, A.; Canto-Canché, B.; Churchill, A.C.L.; Conde-Ferràez, L.; Cools, H.J.; Coutinho, P.M.; Csukai, M.; Dehal, P.; de Wit, P.; Donzelli, B.; Geest, H.G.; van Ham, R.C.H.; Hammond-Kosack, K.E.; Henrissat, B.; Kilian, A.; Kobayashi, A.K.; Koopmann, E.; Kourmpetis, Y.; Kuzniar, A.; Lindquist, E.; Lombard, V.; Maliepaard, C.; Martins, N.; Mehrabi, R.; Nap, J.P.H.; Ponomarenko, A.; Rudd, J.J.; Salamov, A.; Schmutz, J.; Schouten, H.J.; Shapiro, H.; Stergiopoulos, I.; Torriani, S.F.F.; Tu, H.; de Vries, R.P.; Waalwijk, C.; Ware, S.B.; Wiebenga, A.; Zwiers, L.H.; Oliver, R.P.; Grigoriev, I.V.; Kema, G.H.J.

    2011-01-01

    The plant-pathogenic fungus Mycosphaerella graminicola causes septoria tritici blotch, one of the most economically important diseases of wheat worldwide and a potential threat to global food production. Unlike most other plant pathogens, M. graminicola has a long latent period during which it seems

  3. Antifungal Depsidone Metabolites from Cordyceps dipterigena, an Endophytic Fungus Antagonistic to the Phytopathogen Gibberella fujikuroi

    Science.gov (United States)

    Varughese, Titto; Riosa, Nivia; Higginbotham, Sarah; Arnold, A. Elizabeth; Coley, Phyllis D.; Kursar, Thomas A.; Gerwick, William H.; Cubilla Rios, L.

    2012-01-01

    Among thirty four endophytic fungal strains screened for in vitro antagonism, the endophytic fungus Cordyceps dipterigena was found to strongly inhibit mycelial growth of the plant pathogenic fungus Gibberella fujikuroi. Two new depsidone metabolites, cordycepsidone A (1) and cordycepsidone B (2), were isolated from the PDA culture extract of C. dipterigena and identified as being responsible for the antifungal activity. Elucidation of their chemical structures was carried out using 1D and 2D NMR spectroscopy in combination with IR and MS spectroscopic data. Cordycepsidone A displayed strong and dose-dependent antifungal activity against the plant pathogenic fungus Gibberella fujikuroi. The isolates were inactive in bioassays for malaria (Plasmodium falciparum), leishmaniasis (Leishmania donovani), Chagas’s disease (Trypanosoma cruzi), and cytotoxicity at 10 μg/mL. The compounds were also found to be inactive against several bacterial strains at 50 μg/mL. PMID:22707798

  4. Conserved nematode signalling molecules elicit plant defenses and pathogen resistance

    OpenAIRE

    Manosalva, P; Manohar, M; von Reuss, S.; Chen, S.; Koch, A; Kaplan, F; Choe, A.; Micikas, R.; X. Wang; Kogel, K.; Sternberg, P.; Williamson, V; Schroeder, D; Klessig, F.

    2015-01-01

    Plant-defense responses are triggered by perception of conserved microbe-associated molecular patterns (MAMPs), for example, flagellin or peptidoglycan. However, it remained unknown whether plants can detect conserved molecular patterns derived from plant-parasitic animals, including nematodes. Here we show that several genera of plant-parasitic nematodes produce small molecules called ascarosides, an evolutionarily conserved family of nematode pheromones. Picomolar to micromolar concentratio...