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Sample records for citrus pathogen alternaria

  1. Overexpression of citrus polygalacturonase-inhibiting protein in citrus black rot pathogen Alternaria citri.

    Science.gov (United States)

    Katoh, Hiroshi; Nalumpang, Sarunya; Yamamoto, Hiroyuki; Akimitsu, Kazuya

    2007-05-01

    The rough lemon (Citrus jambhiri) gene encoding polygalacturonase-inhibiting protein (RlemPGIPA) was overexpressed in the pathogenic fungus Alternaria citri. The overexpression mutant AcOPI6 retained the ability to utilize pectin as a sole carbon source, and the overexpression of polygalacturonase-inhibiting protein did not have any effect on the growth of AcOPI6 in potato dextrose and pectin medium. The pathogenicity of AcOPI6 to cause a black rot symptom in citrus fruits was also unchanged. Polygalacturonase-inhibiting protein was secreted together with endopolygalacturonase into culture filtrates of AcOPI6, and oligogalacturonides were digested from polygalacturonic acid by both proteins in the culture filtrates. The reaction mixture containing oligogalacturonides possessed activity for induction of defense-related gene, RlemLOX, in rough lemon leaves.

  2. A Virulence-Reducing Mutation in the Postharvest Citrus Pathogen Alternaria citri.

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    Katoh, H; Isshiki, A; Masunaka, A; Yamamoto, H; Akimitsu, K

    2006-09-01

    ABSTRACT Alternaria citri causes Alternaria black rot, a postharvest fruit disease, on a broad range of citrus cultivars. We previously described that an endopolygalacturonase minus mutant of A. citri caused significantly less black rot in citrus fruit. To search for other essential factors causing symptoms in addition to endopolygalacturonase, a random mutation analysis of pathogenicity was performed using restriction enzyme-mediated integration. Three isolates among 1,694 transformants of A. citri had a loss in pathogenicity in a citrus peel assay, and one of these three mutants was a histidine auxotroph. Gene AcIGPD that encodes imidazole glycerol phosphate dehydratase, the sixth enzyme in the histidine biosynthetic pathway, was cloned, and the mutant containing the disrupted target gene, AcIGPD, caused less black rot.

  3. Characterization of Citrus-Associated Alternaria Species in Mediterranean Areas

    Science.gov (United States)

    Garganese, Francesca; Schena, Leonardo; Siciliano, Ilenia; Prigigallo, Maria Isabella; Spadaro, Davide; De Grassi, Anna; Ippolito, Antonio

    2016-01-01

    Alternaria brown spot is one of the most important diseases of tangerines and their hybrids worldwide. Recently, outbreaks in Mediterranean areas related to susceptible cultivars, refocused attention on the disease. Twenty representatives were selected from a collection of 180 isolates of Alternaria spp. from citrus leaves and fruit. They were characterized along with reference strains of Alternaria spp. Micro- and macroscopic characteristics separated most Alternaria isolates into six morphotypes referable to A. alternata (5) and A. arborescens (1). Phylogenetic analyses, based on endopolygalacturonase (endopg) and internal transcribed spacer (ITS), confirmed this finding. Moreover, a five-gene phylogeny including two anonymous genomics regions (OPA 1–3 and OPA 2–1), and the beta-tubulin gene (ß-tub), produced a further clustering of A. alternata into three clades. This analysis suggested the existence of intra-species molecular variability. Investigated isolates showed different levels of virulence on leaves and fruit. In particular, the pathogenicity on fruit seemed to be correlated with the tissue of isolation and the clade. The toxigenic behavior of Alternaria isolates was also investigated, with tenuazonic acid (TeA) being the most abundant mycotoxin (0.2–20 mg/L). Isolates also synthesized the mycotoxins alternariol (AOH), its derivate alternariol monomethyl ether (AME), and altenuene (ALT), although to a lesser extent. AME production significantly varied among the six morphotypes. The expression of pksJ/pksH, biosynthetic genes of AOH/AME, was not correlated with actual toxin production, but it was significantly different between the two genotypes and among the four clades. Finally, ten isolates proved to express the biosynthetic genes of ACTT1 phytotoxin, and thus to be included in the Alternaria pathotype tangerine. A significant correlation between pathogenicity on leaves and ACTT1 gene expression was recorded. The latter was significantly

  4. Citrus Black Rot is Caused by Phylogenetically Distinct Lineages of Alternaria alternata.

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    Peever, T L; Carpenter-Boggs, L; Timmer, L W; Carris, L M; Bhatia, A

    2005-05-01

    ABSTRACT Phylogenetic analysis revealed that isolates of Alternaria alternata causing black rot of citrus were associated with six well-supported evolutionary lineages. Isolates recovered from brown spot lesions on Minneola tangelo, leaf spot lesions on rough lemon, and healthy citrus tissue and noncitrus hosts were related closely to isolates from black-rotted fruit. Phylogenies estimated independently from DNA sequence data from an endopolygalacturonase gene (endoPG) and two anonymous regions of the genome (OPA1-3 and OPA2-1) had similar topologies, and phylogenetic analysis was performed on the combined data set. In the combined phylogeny, isolates from diverse ecological niches on citrus and noncitrus hosts were distributed in eight clades. Isolates from all lineages, regardless of ecological or host association, caused black rot in fruit inoculation assays, demonstrating that small-spored Alternaria isolates associated with different ecological niches on citrus and other plant hosts are potential black rot pathogens. These data also indicated that the fungi associated with black-rotted fruit do not form a natural evolutionary group distinct from other Alternaria pathogens and saprophytes associated with citrus. The use of the name A. citri to describe fungi associated with citrus black rot is not justified and it is proposed that citrus black rot fungi be referred to as A. alternata.

  5. Alternaria

    NARCIS (Netherlands)

    Wenneker, M.

    2015-01-01

    The genus Alternaria consists of approximately 250 species and has a worldwide distribution. As plant pathogens Alternaria spp. infect a diversity of plants. Several different cultivated crops are affected, causing severe damage and crop losses. Alternaria leaf blotch and associated premature leaf d

  6. Alternaria

    NARCIS (Netherlands)

    Wenneker, M.

    2015-01-01

    The genus Alternaria consists of approximately 250 species and has a worldwide distribution. As plant pathogens Alternaria spp. infect a diversity of plants. Several different cultivated crops are affected, causing severe damage and crop losses. Alternaria leaf blotch and associated premature leaf

  7. Green Fluorescent Detection of Fungal Colonization and Endopolygalacturonase Gene Expression in the Interaction of Alternaria citri with Citrus.

    Science.gov (United States)

    Isshiki, A; Ohtani, K; Kyo, M; Yamamoto, H; Akimitsu, K

    2003-07-01

    ABSTRACT Alternaria citri, a postharvest pathogen, produces endopolygalacturonase (endoPG) and causes black rot on citrus fruit. We previously described that an endoPG-disrupted mutant of Alternaria citri was significantly reduced in its ability to macerate plant tissue and cause black rot symptoms on citrus. In order to investigate colonization of citrus fruit tissues by Alternaria citri, pTEFEGFP carrying a green fluorescent protein (GFP) gene was introduced into wild-type Alternaria citri and its endoPG-disrupted mutant (M60). Green fluorescence was observed in spores, germ tubes, appressoria, and infection hyphae of transformants G1 (derived from wild type) and GM4 (derived from M60). Hyphae of G1 but not GM4 vertically penetrated the peel, but the hyphae of both G1 and GM4 spread equally in the juice sac area of citrus fruit. Green fluorescence of Alternaria citri transformant EPG7 carrying a GFP gene under control of the endoPG gene promoter of Alternaria citri was induced by pectin in the peel during the infection stage, but repressed completely in the juice sac area, likely by carbon catabolite repression by sugars in the juice.

  8. A Major Facilitator Superfamily Transporter-Mediated Resistance to Oxidative Stress and Fungicides Requires Yap1, Skn7, and MAP Kinases in the Citrus Fungal Pathogen Alternaria alternata

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    Chen, Li-Hung; Tsai, Hsieh-Chin; Yu, Pei-Ling

    2017-01-01

    Major Facilitator Superfamily (MFS) transporters play an important role in multidrug resistance in fungi. We report an AaMFS19 gene encoding a MFS transporter required for cellular resistance to oxidative stress and fungicides in the phytopathogenic fungus Alternaria alternata. AaMFS19, containing 12 transmembrane domains, displays activity toward a broad range of substrates. Fungal mutants lacking AaMFS19 display profound hypersensitivities to cumyl hydroperoxide, potassium superoxide, many singlet oxygen-generating compounds (eosin Y, rose Bengal, hematoporphyrin, methylene blue, and cercosporin), and the cell wall biosynthesis inhibitor, Congo red. AaMFS19 mutants also increase sensitivity to copper ions, clotrimazole, fludioxonil, and kocide fungicides, 2-chloro-5-hydroxypyridine (CHP), and 2,3,5-triiodobenzoic acid (TIBA). AaMFS19 mutants induce smaller necrotic lesions on leaves of a susceptible citrus cultivar. All observed phenotypes in the mutant are restored by introducing and expressing a wild-type copy of AaMFS19. The wild-type strain of A. alternata treated with either CHP or TIBA reduces radial growth and formation and germination of conidia, increases hyphal branching, and results in decreased expression of the AaMFS19 gene. The expression of AaMFS19 is regulated by the Yap1 transcription activator, the Hog1 and Fus3 mitogen-activated protein (MAP) kinases, the ‘two component’ histidine kinase, and the Skn7 response regulator. Our results demonstrate that A. alternata confers resistance to different chemicals via a membrane-bound MFS transporter. PMID:28060864

  9. Large-spored Alternaria pathogens in section Porri disentangled

    NARCIS (Netherlands)

    Woudenberg, J.H.C.; Truter, M.; Groenewald, J.Z.; Crous, P.W.

    2014-01-01

    The omnipresent fungal genus Alternaria was recently divided into 24 sections based on molecular and morphological data. Alternaria sect. Porri is the largest section, containing almost all Alternaria species with medium to large conidia and long beaks, some of which are important plant pathogens (e

  10. Large-spored Alternaria pathogens in section Porri disentangled

    NARCIS (Netherlands)

    Woudenberg, J.H.C.; Truter, M.; Groenewald, J.Z.; Crous, P.W.

    2014-01-01

    The omnipresent fungal genus Alternaria was recently divided into 24 sections based on molecular and morphological data. Alternaria sect. Porri is the largest section, containing almost all Alternaria species with medium to large conidia and long beaks, some of which are important plant pathogens (e

  11. Large-spored Alternaria pathogens in section Porri disentangled.

    Science.gov (United States)

    Woudenberg, J H C; Truter, M; Groenewald, J Z; Crous, P W

    2014-09-01

    The omnipresent fungal genus Alternaria was recently divided into 24 sections based on molecular and morphological data. Alternaria sect. Porri is the largest section, containing almost all Alternaria species with medium to large conidia and long beaks, some of which are important plant pathogens (e.g. Alternaria porri, A. solani and A. tomatophila). We constructed a multi-gene phylogeny on parts of the ITS, GAPDH, RPB2, TEF1 and Alt a 1 gene regions, which, supplemented with morphological and cultural studies, forms the basis for species recognition in sect. Porri. Our data reveal 63 species, of which 10 are newly described in sect. Porri, and 27 species names are synonymised. The three known Alternaria pathogens causing early blight on tomato all cluster in one clade, and are synonymised under the older name, A. linariae. Alternaria protenta, a species formerly only known as pathogen on Helianthus annuus, is also reported to cause early blight of potato, together with A. solani and A. grandis. Two clades with isolates causing purple blotch of onion are confirmed as A. allii and A. porri, but the two species cannot adequately be distinguished based on the number of beaks and branches as suggested previously. This is also found among the pathogens of Passifloraceae, which are reduced from four to three species. In addition to the known pathogen of sweet potato, A. bataticola, three more species are delineated of which two are newly described. A new Alternaria section is also described, comprising two large-spored Alternaria species with concatenate conidia.

  12. Pathogenic, morphological and molecular characteristics of Alternaria Tenuissima from soybean

    OpenAIRE

    Jasnić Stevan M.; Marjanović Žaklina S.; Vidić Miloš B.; Bagi Ferenc F.; Budakov Dragana B.; Pavlović Snežana Đ.; Stojšin Vera B.

    2011-01-01

    During 2008 and 2009 phytopathological isolations were done from soybean plants and seed samples from several localities in Serbia. A total of 19 isolates of Alternaria spp. were isolated, 13 from the seed and 3 from both leaf and stem. In order to determine and characterize isolates, cultural, morphological, molecular and pathogenic characteristics were thoroughly investigated. The slowest growth of the examined isolates was noted on Malt agar (MA) with average colony diameter of 42.9 ...

  13. Pathogenic, morphological and molecular characteristics of Alternaria Tenuissima from soybean

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    Jasnić Stevan M.

    2011-01-01

    Full Text Available During 2008 and 2009 phytopathological isolations were done from soybean plants and seed samples from several localities in Serbia. A total of 19 isolates of Alternaria spp. were isolated, 13 from the seed and 3 from both leaf and stem. In order to determine and characterize isolates, cultural, morphological, molecular and pathogenic characteristics were thoroughly investigated. The slowest growth of the examined isolates was noted on Malt agar (MA with average colony diameter of 42.9 mm after 7 days of incubation. On other two media (V8 and PCA, colony growth was uniform and faster, with average diameter of 66.8 mm and 66.1 mm, respectively. Isolates of fungi form unbranched or poorly branched conidial chains on short unbranched conidiophores. Conidia are dark in colour, multicellular with transverse and longitudinal septae. They are of different size regarding the place of formation in the chain. Based on these characteristics, the tested isolates were determined as Alternaria tenuissima. Molecular identification with sequencing of ITS1-5.8S-ITS2 rDNA verified that investigated isolates belong to Alternaria tenuissima group. Pathogenicity test proved that all isolates were more or less virulent to soybean seed (12.5% to 40% of rotten seeds, while pathogenicity on plants was poorly expressed.

  14. Assessment of protein silver nanoparticles toxicity against pathogenic Alternaria solani.

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    Abdel-Hafez, Sobhy I I; Nafady, Nivien A; Abdel-Rahim, Ismail R; Shaltout, Abeer M; Daròs, José-Antonio; Mohamed, Mohamed A

    2016-12-01

    Mycogenic synthesis of silver nanoparticles (AgNPs) was carried out in the present investigation using an aqueous extract of endophytic non-pathogenic Alternaria solani F10 (KT721914). The mycosynthesized AgNPs were characterized by means of spectroscopic and microscopic techniques. The surface plasmon resonance found at 430 nm confirmed the formation of stable AgNPs for several weeks at room temperature. Also, the results revealed the formation of spherical and monodispersed AgNPs with an average size of 14.8 ± 1.2 nm. The FT-IR spectrum suggested that the fungal extracellular proteins and secondary metabolites had the role in Ag reduction and AgNPs capping of which protein Ag nanoconjugates were formed. Furthermore, the mycosynthesized AgNPs exhibited potent antifungal activity against different pathogenic isolates of the same Alternaria solani fungus, the causal pathogen of tomato early blight disease. The antifungal efficiency of the AgNPs at 1, 5 and 10 ppm were evaluated for 8 days after incubation by measuring the inhibition rate of fungal radial growth. The results were further supported by investigating fungal hyphae morphology alteration by scanning and transmission electron microscopy. Treated fungal hyphae showed formation of pits and pores. Also, the mycosynthesized AgNPs were able to pass and distribute throughout the fungal cell area and interact with the cell components.

  15. Digital PCR for detection of citrus pathogens

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    Citrus trees are often infected with multiple pathogens of economic importance, especially those with insect or mite vectors. Real-time/quantitative PCR (qPCR) has been used for high-throughput detection and relative quantification of pathogens; however, target reference or standards are required. I...

  16. Fine Mapping for Identification of Citrus Alternaria Brown Spot Candidate Resistance Genes and Development of New SNP Markers for Marker-Assisted Selection

    Science.gov (United States)

    Cuenca, Jose; Aleza, Pablo; Garcia-Lor, Andres; Ollitrault, Patrick; Navarro, Luis

    2016-01-01

    Alternaria brown spot (ABS) is a serious disease affecting susceptible citrus genotypes, which is a strong concern regarding citrus breeding programs. Resistance is conferred by a recessive locus (ABSr) previously located by our group within a 3.3 Mb genome region near the centromere in chromosome III. This work addresses fine-linkage mapping of this region for identifying candidate resistance genes and develops new molecular markers for ABS-resistance effective marker-assisted selection (MAS). Markers closely linked to ABSr locus were used for fine mapping using a 268-segregating diploid progeny derived from a heterozygous susceptible × resistant cross. Fine mapping limited the genomic region containing the ABSr resistance gene to 366 kb, flanked by markers at 0.4 and 0.7 cM. This region contains nine genes related to pathogen resistance. Among them, eight are resistance (R) gene homologs, with two of them harboring a serine/threonine protein kinase domain. These two genes along with a gene encoding a S-adenosyl-L-methionine-dependent-methyltransferase protein, should be considered as strong candidates for ABS-resistance. Moreover, the closest SNP was genotyped in 40 citrus varieties, revealing very high association with the resistant/susceptible phenotype. This new marker is currently used in our citrus breeding program for ABS-resistant parent and cultivar selection, at diploid, triploid and tetraploid level. PMID:28066498

  17. Evaluation of Antibacterial Activities of Citrus limon, Citrus reticulata, and Citrus grandis Against Pathogenic Bacteria

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    Sholeh Saeb

    2016-11-01

    Full Text Available Background: Microorganisms resistant to most antibiotics are rapidly spreading, and there is an urgent and continuous need for novel antimicrobial compounds. The genus Citrus belongs to the family Rutaceae has many biologically active secondary metabolites. Objectives: The purpose of this study was to evaluate antimicrobial activity of essential oil and extract of Lemon (Citrus limon, Mandarin (Citrus reticulata and Pummelo (Citrus grandis against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Salmonella typhi. Materials and Methods: The fresh Citrus leaves were shade-dried and powdered. Antimicrobial metabolites were extracted from them by 80% methanol for extract and using a Clevenger-type apparatus for essential oil. Eight different concentrations of the each leaf extract and essential oil were prepared. The antimicrobial susceptibility assay of Citrus leaves metabolites were subjected against four bacterial strains by agar disc diffusion and E-test method. Results: In this study, minimum inhibitory concentrations (MIC of different Citrus leaf extracts were determined against all four food-borne pathogens. The C. grandis leaf essential oil had potent antimicrobial activity against all four pathogens, and the C. limon leaf essential oil was effective on Gram-positive bacteria. S. typhi was resistant against two leaves essential oils. Conclusions: The results showed that there was no antimicrobial activity effect in all extracts on tested bacteria. In this study, the antibacterial effect of essential oil of Citrus leaves on four strains of pathogenic microorganisms was confirmed. The C. grandis leaf essential oil had the most powerful antimicrobial properties, suggesting its potential application as natural preservative in foods or an effective medicine against different pathogenic microbes. Key words: Antibacterial activity, E-test, Citr

  18. New Pseudomonas spp. Are Pathogenic to Citrus.

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    Farid Beiki

    Full Text Available Five putative novel Pseudomonas species shown to be pathogenic to citrus have been characterized in a screening of 126 Pseudomonas strains isolated from diseased citrus leaves and stems in northern Iran. The 126 strains were studied using a polyphasic approach that included phenotypic characterizations and phylogenetic multilocus sequence analysis. The pathogenicity of these strains against 3 cultivars of citrus is demonstrated in greenhouse and field studies. The strains were initially grouped phenotypically and by their partial rpoD gene sequences into 11 coherent groups in the Pseudomonas fluorescens phylogenetic lineage. Fifty-three strains that are representatives of the 11 groups were selected and analyzed by partial sequencing of their 16S rRNA and gyrB genes. The individual and concatenated partial sequences of the three genes were used to construct the corresponding phylogenetic trees. The majority of the strains were identified at the species level: P. lurida (5 strains, P. monteilii (2 strains, P. moraviensis (1 strain, P. orientalis (16 strains, P. simiae (7 strains, P. syringae (46 strains, distributed phylogenetically in at least 5 pathovars, and P. viridiflava (2 strains. This is the first report of pathogenicity on citrus of P. orientalis, P. simiae, P. lurida, P. moraviensis and P. monteilii strains. The remaining 47 strains that could not be identified at the species level are considered representatives of at least 5 putative novel Pseudomonas species that are not yet described.

  19. New Pseudomonas spp. Are Pathogenic to Citrus.

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    Beiki, Farid; Busquets, Antonio; Gomila, Margarita; Rahimian, Heshmat; Lalucat, Jorge; García-Valdés, Elena

    2016-01-01

    Five putative novel Pseudomonas species shown to be pathogenic to citrus have been characterized in a screening of 126 Pseudomonas strains isolated from diseased citrus leaves and stems in northern Iran. The 126 strains were studied using a polyphasic approach that included phenotypic characterizations and phylogenetic multilocus sequence analysis. The pathogenicity of these strains against 3 cultivars of citrus is demonstrated in greenhouse and field studies. The strains were initially grouped phenotypically and by their partial rpoD gene sequences into 11 coherent groups in the Pseudomonas fluorescens phylogenetic lineage. Fifty-three strains that are representatives of the 11 groups were selected and analyzed by partial sequencing of their 16S rRNA and gyrB genes. The individual and concatenated partial sequences of the three genes were used to construct the corresponding phylogenetic trees. The majority of the strains were identified at the species level: P. lurida (5 strains), P. monteilii (2 strains), P. moraviensis (1 strain), P. orientalis (16 strains), P. simiae (7 strains), P. syringae (46 strains, distributed phylogenetically in at least 5 pathovars), and P. viridiflava (2 strains). This is the first report of pathogenicity on citrus of P. orientalis, P. simiae, P. lurida, P. moraviensis and P. monteilii strains. The remaining 47 strains that could not be identified at the species level are considered representatives of at least 5 putative novel Pseudomonas species that are not yet described.

  20. Overexpression of a Gene Encoding a Catabolite Repression Element in Alternaria citri Causes Severe Symptoms of Black Rot in Citrus Fruit.

    Science.gov (United States)

    Katoh, H; Ohtani, K; Yamamoto, H; Akimitsu, K

    2007-05-01

    ABSTRACT A gene (AcCreA) encoding a catabolite repression element (CreA) with (two zinc fingers of the Cys(2)His(2) type was isolated from the postharvest fungal pathogen Alternaria citri. The AcCreA overexpression mutant AcOEC2 of A. citri showed normal growth on pectin medium and on segments of peel or the juice sac area from citrus fruit. Production of endopolygalacturonase, an essential virulence factor of this pathogen, was similar in AcOEC2 and the wild type in pectin-containing media. However, addition of glucose to the medium showed that carbon catabolite repression of endopolygalacturonase gene (Acpg1) expression, as well as endopolygalacturonase production, was lost in AcOEC2. The wild-type strain of A. citri causes rot mainly in the central axis of citrus fruit without development of rotting in the juice sac area; however, AcOEC2 caused severe black rot symptoms in both the central axis and juice sac areas. These results indicate that AcCreA-mediated catabolite repression controls the virulence or infection of this pathogen, and that the wild-type A. citri does not cause symptoms in the juice sac area due to carbon catabolite repression by sugars in the juice of the juice sac area.

  1. Molecular genetic characterisation of the Asc locus of tomato conferring resistance to the fungal pathogen Alternaria alternata f. sp. lycopersici

    NARCIS (Netherlands)

    Biezen, E.A. van der; Overduin, B.; Kneppers, T.J.A.; Mesbah, L.A.; Nijkamp, H.J.J.; Hille, J.

    1994-01-01

    The Alternaria stem canker disease of tomato is caused by the fungal pathogen Alternaria alternata f. sp. lycopersici and its host-selective AAL-toxins. Resistance to the pathogen and insensitivity to the toxins are conferred by the Asc locus on chromosome 3L. Sensitivity to AAL-toxins is a relative

  2. Multilocus phylogeny and MALDI-TOF analysis of the plant pathogenic species Alternaria dauci and relatives.

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    Brun, Sophie; Madrid, Hugo; Gerrits Van Den Ende, Bert; Andersen, Birgitte; Marinach-Patrice, Carine; Mazier, Dominique; De Hoog, G Sybren

    2013-01-01

    The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of morphologically similar taxa. This study aimed to assess if strains of four closely-related plant pathogens, i.e., accurately Alternaria dauci (ten strains), Alternaria porri (six), Alternaria solani (ten), and Alternaria tomatophila (ten) could be identified using multilocus phylogenetic analysis and Matrix-Assisted Laser Desorption Ionisation Time of Flight (MALDI-TOF) profiling of proteins. Phylogenetic analyses were performed on three loci, i.e., the internal transcribed spacer (ITS) region of rRNA, and the glyceraldehyde-3-phosphate dehydrogenase (gpd) and Alternaria major antigen (Alt a 1) genes. Phylogenetic trees based on ITS sequences did not differentiate strains of A. solani, A. tomatophila, and A. porri, but these three species formed a clade separate from strains of A. dauci. The resolution improved in trees based on gpd and Alt a 1, which distinguished strains of the four species as separate clades. However, none provided significant bootstrap support for all four species, which could only be achieved when results for the three loci were combined. MALDI-TOF-based dendrograms showed three major clusters. The first comprised all A. dauci strains, the second included five strains of A. porri and one of A. solani, and the third included all strains of A. tomatophila, as well as all but one strain of A. solani, and one strain of A. porri. Thus, this study shows the usefulness of MALDI-TOF mass spectrometry as a promising tool for identification of these four species of Alternaria which are closely-related plant pathogens. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

  3. Restyling Alternaria

    NARCIS (Netherlands)

    Woudenberg, J.H.C.

    2015-01-01

    The omnipresent dematiaceous hyphomycete genus Alternaria is associated with a wide variety of substrates including seeds, plants, agricultural products, humans, soil and even the atmosphere. It includes saprophytic, endophytic and pathogenic species, among which multiple plant pathogens, post-harve

  4. Restyling Alternaria

    NARCIS (Netherlands)

    Woudenberg, J.H.C.

    2015-01-01

    The omnipresent dematiaceous hyphomycete genus Alternaria is associated with a wide variety of substrates including seeds, plants, agricultural products, humans, soil and even the atmosphere. It includes saprophytic, endophytic and pathogenic species, among which multiple plant pathogens,

  5. Developing cryotherapy to eliminate graft-transmissible pathogens in citrus

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    This article summarizes research being conducted as part of a project funded by the California Citrus Research Board to develop cryotherapy (freezing buds in liquid nitrogen, and then recovering them) as a viable method for elimination of graft transmissible pathogens from Citrus. There are current...

  6. The Alternaria genomes database: a comprehensive resource for a fungal genus comprised of saprophytes, plant pathogens, and allergenic species.

    Science.gov (United States)

    Dang, Ha X; Pryor, Barry; Peever, Tobin; Lawrence, Christopher B

    2015-03-25

    Alternaria is considered one of the most common saprophytic fungal genera on the planet. It is comprised of many species that exhibit a necrotrophic phytopathogenic lifestyle. Several species are clinically associated with allergic respiratory disorders although rarely found to cause invasive infections in humans. Finally, Alternaria spp. are among the most well known producers of diverse fungal secondary metabolites, especially toxins. We have recently sequenced and annotated the genomes of 25 Alternaria spp. including but not limited to many necrotrophic plant pathogens such as A. brassicicola (a pathogen of Brassicaceous crops like cabbage and canola) and A. solani (a major pathogen of Solanaceous plants like potato and tomato), and several saprophytes that cause allergy in human such as A. alternata isolates. These genomes were annotated and compared. Multiple genetic differences were found in the context of plant and human pathogenicity, notably the pro-inflammatory potential of A. alternata. The Alternaria genomes database was built to provide a public platform to access the whole genome sequences, genome annotations, and comparative genomics data of these species. Genome annotation and comparison were performed using a pipeline that integrated multiple computational and comparative genomics tools. Alternaria genome sequences together with their annotation and comparison data were ported to Ensembl database schemas using a self-developed tool (EnsImport). Collectively, data are currently hosted using a customized installation of the Ensembl genome browser platform. Recent efforts in fungal genome sequencing have facilitated the studies of the molecular basis of fungal pathogenicity as a whole system. The Alternaria genomes database provides a comprehensive resource of genomics and comparative data of an important saprophytic and plant/human pathogenic fungal genus. The database will be updated regularly with new genomes when they become available. The

  7. Genetically based location from triploid populations and gene ontology of a 3.3-mb genome region linked to Alternaria brown spot resistance in citrus reveal clusters of resistance genes.

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    José Cuenca

    Full Text Available Genetic analysis of phenotypical traits and marker-trait association in polyploid species is generally considered as a challenge. In the present work, different approaches were combined taking advantage of the particular genetic structures of 2n gametes resulting from second division restitution (SDR to map a genome region linked to Alternaria brown spot (ABS resistance in triploid citrus progeny. ABS in citrus is a serious disease caused by the tangerine pathotype of the fungus Alternaria alternata. This pathogen produces ACT-toxin, which induces necrotic lesions on fruit and young leaves, defoliation and fruit drop in susceptible genotypes. It is a strong concern for triploid breeding programs aiming to produce seedless mandarin cultivars. The monolocus dominant inheritance of susceptibility, proposed on the basis of diploid population studies, was corroborated in triploid progeny. Bulk segregant analysis coupled with genome scan using a large set of genetically mapped SNP markers and targeted genetic mapping by half tetrad analysis, using SSR and SNP markers, allowed locating a 3.3 Mb genomic region linked to ABS resistance near the centromere of chromosome III. Clusters of resistance genes were identified by gene ontology analysis of this genomic region. Some of these genes are good candidates to control the dominant susceptibility to the ACT-toxin. SSR and SNP markers were developed for efficient early marker-assisted selection of ABS resistant hybrids.

  8. Genetically based location from triploid populations and gene ontology of a 3.3-mb genome region linked to Alternaria brown spot resistance in citrus reveal clusters of resistance genes.

    Science.gov (United States)

    Cuenca, José; Aleza, Pablo; Vicent, Antonio; Brunel, Dominique; Ollitrault, Patrick; Navarro, Luis

    2013-01-01

    Genetic analysis of phenotypical traits and marker-trait association in polyploid species is generally considered as a challenge. In the present work, different approaches were combined taking advantage of the particular genetic structures of 2n gametes resulting from second division restitution (SDR) to map a genome region linked to Alternaria brown spot (ABS) resistance in triploid citrus progeny. ABS in citrus is a serious disease caused by the tangerine pathotype of the fungus Alternaria alternata. This pathogen produces ACT-toxin, which induces necrotic lesions on fruit and young leaves, defoliation and fruit drop in susceptible genotypes. It is a strong concern for triploid breeding programs aiming to produce seedless mandarin cultivars. The monolocus dominant inheritance of susceptibility, proposed on the basis of diploid population studies, was corroborated in triploid progeny. Bulk segregant analysis coupled with genome scan using a large set of genetically mapped SNP markers and targeted genetic mapping by half tetrad analysis, using SSR and SNP markers, allowed locating a 3.3 Mb genomic region linked to ABS resistance near the centromere of chromosome III. Clusters of resistance genes were identified by gene ontology analysis of this genomic region. Some of these genes are good candidates to control the dominant susceptibility to the ACT-toxin. SSR and SNP markers were developed for efficient early marker-assisted selection of ABS resistant hybrids.

  9. Genetically Based Location from Triploid Populations and Gene Ontology of a 3.3-Mb Genome Region Linked to Alternaria Brown Spot Resistance in Citrus Reveal Clusters of Resistance Genes

    Science.gov (United States)

    Cuenca, José; Aleza, Pablo; Vicent, Antonio; Brunel, Dominique; Ollitrault, Patrick; Navarro, Luis

    2013-01-01

    Genetic analysis of phenotypical traits and marker-trait association in polyploid species is generally considered as a challenge. In the present work, different approaches were combined taking advantage of the particular genetic structures of 2n gametes resulting from second division restitution (SDR) to map a genome region linked to Alternaria brown spot (ABS) resistance in triploid citrus progeny. ABS in citrus is a serious disease caused by the tangerine pathotype of the fungus Alternaria alternata. This pathogen produces ACT-toxin, which induces necrotic lesions on fruit and young leaves, defoliation and fruit drop in susceptible genotypes. It is a strong concern for triploid breeding programs aiming to produce seedless mandarin cultivars. The monolocus dominant inheritance of susceptibility, proposed on the basis of diploid population studies, was corroborated in triploid progeny. Bulk segregant analysis coupled with genome scan using a large set of genetically mapped SNP markers and targeted genetic mapping by half tetrad analysis, using SSR and SNP markers, allowed locating a 3.3 Mb genomic region linked to ABS resistance near the centromere of chromosome III. Clusters of resistance genes were identified by gene ontology analysis of this genomic region. Some of these genes are good candidates to control the dominant susceptibility to the ACT-toxin. SSR and SNP markers were developed for efficient early marker-assisted selection of ABS resistant hybrids. PMID:24116149

  10. Enhancement of the citrus immune system provides effective resistance against Alternaria brown spot disease.

    Science.gov (United States)

    Llorens, Eugenio; Fernández-Crespo, Emma; Vicedo, Begonya; Lapeña, Leonor; García-Agustín, Pilar

    2013-01-15

    In addition to basal defense mechanisms, plants are able to develop enhanced defense mechanisms such as induced resistance (IR) upon appropriate stimulation. We recently described the means by which several carboxylic acids protect Arabidopsis and tomato plants against fungi. In this work, we demonstrate the effectiveness of hexanoic acid (Hx) in the control of Alternaria brown spot (ABS) disease via enhancement of the immune system of Fortune mandarin. The application of 1mM Hx in irrigation water to 2-year-old Fortune plants clearly reduced the incidence of the disease and led to smaller lesions. We observed that several of the most important mechanisms involved in induced resistance were affected by Hx application. Our results demonstrate enhanced callose deposition in infected plants treated with Hx, which suggests an Hx priming mechanism. Plants treated with the callose inhibitor 2-DDG were more susceptible to the fungus. Moreover, polygalacturonase-inhibiting protein (PGIP) gene expression was rapidly and significantly upregulated in treated plants. However, treatment with Hx decreased the levels of reactive oxygen species (ROS) in infected plants. Hormonal and gene analyses revealed that the jasmonic acid (JA) pathway was activated due to a greater accumulation of 12-oxo-phytodienoic acid (OPDA) and JA along with a rapid accumulation of JA-isoleucine (JA-Ile). Furthermore, we observed a more rapid accumulation of abscisic acid (ABA), which could act as a positive regulator of callose deposition. Thus, our results support the hypothesis that both enhanced physical barriers and the JA signaling pathway are involved in hexanoic acid-induced resistance (Hx-IR) to Alternaria alternata.

  11. 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.

  12. Phytotoxin solanapyrone A produced by Ascochyta rabiei and Alternaria solani is nonessential for pathogenicity, but likely plays ecological roles

    Science.gov (United States)

    Ascochyta rabiei and Alternaria solani, causal agents of chickpea and potato blights respectively, produce the same phytotoxin solanapyrone A (SolA).The toxicity of SolA to plants has been documented, but its role in pathogenicity has not been investigated. In this study, we generated solanapyrone-d...

  13. STUDIES ON ANTIMICROBIAL ACTIVITY AND PHYTOCHEMICAL ANALYSIS OF CITRUS FRUIT JUICES AGAINST SELECTED ENTERIC PATHOGENS

    OpenAIRE

    Bansode.D.S.; Chavan.M.D.

    2012-01-01

    The present study was carried out to find out the antimicrobial activity and phytochemical study of citrus fruit juices viz. Lemon (Citrus limon) and Orange (Citrus ourantium) against medically important selected enteric pathogens. As microorganisms are becoming resistant to present day antibiotics, our study focuses on antimicrobial activity and phytochemical study of Citrus fruit juices against selected enteric pathogens. Biological active compounds present in the medicinal important fruit ...

  14. Cultural, Morphological and Pathogenic Characterization of Alternaria porri Causing Purple Blotch of Onion

    Directory of Open Access Journals (Sweden)

    Sayed Mohammad MOHSIN

    2016-06-01

    Full Text Available Twenty seven (27 isolates of Alternaria porri were isolated from diseased leaf samples collected from different onion growing regions of Bangladesh and characterized for cultural, morphological and pathogenic variabilities. A. porri colonies colony colour ranged between light to dark olivacious and grayish white with irregular, regular with concentric ring and regular without concentric ring shape. Margin of colonies were entire, irregular and wavy with effuse, fluffy and velvety texture. Isolates impregnated media with colour ranged between grey to brown on the reverse of the plates. Growth rate of isolates ranged between 2.433 and 3.950 mm/day with fast growth in isolate DSTR 02 and least in MMBH. Morphological variation in conidia production was between 7.720×103 to 47.02×103 per mm2 with sporulation time 3.33 to 11.00 days. The conidial shape was straight to curve with light to deep brown colour. The number of horizontal and vertical separation in the conidia ranged from 3.00 to 6.00 × 1.00 to 2.00 with size from 11.20 to 39.20 × 4.76 to 11.43 µm. In pathogenicity test isolates also exhibited variations in size of the lesions (2.77 to 7.55 mm produced on onion leaves. The results demonstrate existence of considerable variation in cultural, morphological, and pathogenic characters of A. porri isolates prevalent in Bangladesh environment.

  15. Fungal-specific transcription factor AbPf2 activates pathogenicity in Alternaria brassicicola

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yangrae; Ohm, Robin A.; Grigoriev, Igor V.; Srivastava, Akhil

    2012-12-03

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. To identify molecular determinants of pathogenicity, we created non-pathogenic mutants of a transcription factor-encoding gene, AbPf2. The frequency and timing of germination and appressorium formation on host plants were similar between the non-pathogenic abpf2 mutants and wild-type A. brassicicola. The mutants were also similar in vitro to wild-type A. brassicicola in terms of vegetative growth, conidium production, and responses to a phytoalexin, reactive oxygen species and osmolites. The hyphae of the mutants grew slowly but did not cause disease symptoms on the surface of host plants. Transcripts of the AbPf2 gene increased exponentially soon after wild-type conidia contacted their host plants . A small amount of AbPf2 protein, as monitored using GFP fusions, was present in young, mature conidia. The protein level decreased during saprophytic growth, but increased and was located primarily in fungal nuclei during pathogenesis. Levels of the proteins and transcripts sharply decreased following colonization of host tissues beyond the initial infection site. When expression of the transcription factor was induced in the wild-type during early pathogenesis, 106 fungal genes were also induced in the wild-type but not in the abpf2 mutants. Notably, 33 of the 106 genes encoded secreted proteins, including eight putative effector proteins. Plants inoculated with abpf2 mutants expressed higher levels of genes associated with photosynthesis, the pentose phosphate pathway and primary metabolism, but lower levels of defense-related genes. Our results suggest that AbPf2 is an important regulator of pathogenesis, but does not affect other cellular processes in A. brassicicola.

  16. RESISTÊNCIA DE TOMATEIRO (Lycopersicon esculentum AO PATÓGENO Alternaria solani RESISTANCE OF TOMATO (Lycopersicon esculentum TO Alternaria solani PATHOGEN

    Directory of Open Access Journals (Sweden)

    Wilson Ferreira de Oliveira

    2007-09-01

    resistant were F1 hibrid Hawaii 7998 x Monense and Rotam 4. The genotypes Ohio 4013 and the F1 Hawaii 7998 x Monense hibrid were the ones that more stood out for resistance to these pathogen and could be suitable for future breeding programs.

    KEY-WORDS: Tomato; resistance; Alternaria solani.

  17. Comparison of methodologies for conidia production by Alternaria alternata from citrus Comparação de metodologias para produção de conídios por Alternaria alternata do citros

    Directory of Open Access Journals (Sweden)

    Daniel D. C. Carvalho

    2008-12-01

    Full Text Available Conidia production is a problem in the study of Alternaria alternata from citrus. Thus, this study aimed to compare existing methodologies for conidial production of A. alternata isolated from Ponkan tangerine (2 isolates, Cravo lemon (1 isolate, Pêra orange (2 isolates and Murcott tangor (1 isolate. The methodologies used were conidia production with 12 and 24 hours under white fluorescent light, evaluation with 24 and 48 hours after applying fungal mycelium stress technique, cold stress followed by injury of mycelium and evaluation with 24 hours, using healthy vegetable tissue and the use of black fluorescent near ultraviolet (NUV lamp. Satisfactory result was obtained with A. alternata isolate from Murcott tangor, with the production of 2.8 x 10(5 conidia mL-1, when fungal mycelium was stressed (Petri dish with 66.66% of fungi growth and subsequently 24 h of growth. The use of white light (24 h and black fluorescent NUV lamp also induced expressive conidia production by one isolate of Ponkan tangerine, which produced 17.2 x 10(5 and 10.1 x 10(5 conidia mL-1 and another of Murcott tangor, which produced 13.9 x 10(5 and 10.1 x 10(5 conidia mL-1, respectively. The remaining methodologies analyzed in this study were not able to induce conidia production in satisfactory quantity. The use of both mycelium stress technique and white light (24 h and black fluorescent NUV lamp allowed the production of enough quantities of conidia to be used in vitro (detection of fungitoxic substancesand in vivo (pathogenicity testassays, respectively.A produção de conídios consiste em problema no estudo de Alternaria alternata do citros. Assim, este estudo objetivou comparar metodologias existentes para a produção de conídios de A. alternata por dois isolados de tangerina Ponkan, um de limão Cravo, dois de laranja Pêra e um de tangor Murcott. As metodologias empregadas foram a produção de conídios com 12 e 24 horas sob luz branca, avaliação com 24 e 48

  18. Effect of Alternaria solani exudates on resistant and susceptible potato cultivars from two different pathogen isolates

    Science.gov (United States)

    The resistance phenotypes of two potato cultivars to two isolates of Alternaria solani, causal agent of early blight, were studied under greenhouse conditions. The two isolates contain varying degrees of aggressiveness on both susceptible and resistant phenotypes of potatoes. A bioassay was used to ...

  19. Multilocus phylogeny and MALDI-TOF analysis of the plant pathogenic species Alternaria dauci and relatives

    DEFF Research Database (Denmark)

    Brun, Sophie; Madrid, Hugo; Gerrits Van Den Ende, Bert

    2013-01-01

    -Assisted Laser Desorption Ionisation Time of Flight (MALDI-TOF) profiling of proteins. Phylogenetic analyses were performed on three loci, i.e., the internal transcribed spacer (ITS) region of rRNA, and the glyceraldehyde-3-phosphate dehydrogenase (gpd) and Alternaria major antigen (Alt a 1) genes. Phylogenetic...

  20. Tomato early blight (Alternaria solani): the pathogen, genetics and breeding for resistance

    NARCIS (Netherlands)

    Chaerani, R.; Voorrips, R.E.

    2006-01-01

    Alternaria solani causes diseases on foliage (early blight), basal stems of seedlings (collar rot), stems of adult plants (stem lesions), and fruits (fruit rot) of tomato. Early blight is the most destructive of these diseases and hence receives considerable attention in breeding. For over 60 years,

  1. Multilocus phylogeny and MALDI-TOF analysis of the plant pathogenic species Alternaria dauci and relatives

    NARCIS (Netherlands)

    Brun, S.; Madrid, H.; Gerritis van den Ende, B.; Andersen, B.; Marinach-Patrice, C.; Mazier, D.; de Hoog, G.S.

    2013-01-01

    The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of morphol

  2. Analysis of genetic and pathogenic variation among Alternaria solani in a potato production region

    Science.gov (United States)

    A two-year survey was conducted in a potato production region to investigate the genetic variability within naturally infecting populations of Alternaria solani, the cause of early blight in potato, and between species A. solani and A. dauci. Genetic diversity among 151 isolates was assessed using s...

  3. Identification of the pathogenic fungus causing brown spot on tangerine( Citrus reticulata CV.Hongjv%红橘褐斑病病原鉴定

    Institute of Scientific and Technical Information of China (English)

    陈昌胜; 黄峰; 程兰; 冯春刚; 黄涛江; 李红叶

    2011-01-01

    自2007年起重庆万州的红橘(Citrus reticulata Blanco,CV.Hongjv)上爆发一种未曾见过的病害,损失严重,因病斑褐色,故被称之为褐斑病.褐斑病贯穿柑橘整个生长季节,主要为害叶片和果实,严重时也为害新梢,引起大量落叶和落果,甚至枝梢枯死.为明确其病原,本研究从病区多个果园采集发病的叶片、果实和枝梢,检查和分离培养发现病组织中广泛存在链格孢菌(Alternaria)和炭疽菌(Colletotrichum).致病性试验证明只有链格孢菌才能引起类似褐斑症状,而炭疽菌和空白对照都不产生任何症状.通过比较研究这些链格孢菌菌株的形态学,培养性状和多聚半乳糖醛酸酶(endoPG)基因的部分序列,可以断定红橘褐斑病的病原为交链格孢菌[A.alternate(Fr.)Keissler].病原性质的确定将为红橘褐斑病发生规律的研究和控制奠定基础.%An unknown disease has been breaking out and causing a great loss on Hongjv (Citrus reticulata Blanco, CV. Hongjv) since 2007 in Wanzhou, Zhongqing, China. The disease was characterized as the brown spot on affected tissues and named "brown spot disease" temporarily. The disease occurs around a growing season and the severe affected leaves and fruits drop quickly. To determine the causing agent, the infected leaves, fruits and shoots were collected from different orchards. Typical conidiospores and cultures of Alternaria and Colletotrichum were always observed and isolated from infected tissues. However, pathogenici-ty test showed that only the isolates of Alternaria were pathogenic to the leaves and fruits of tangerine (Ci. Reticulata CV. Ponkan). Based on the study of morphology, cultural feature and partial sequence of an endopo-lygalacturonase gene (endoPG), the pathogenic Alternaria was identified as A. Alternate (Fr. ) Keissler. The clarification of pathogen would benefit to the study on epidemiology and control of this disease.

  4. Multiplexed lateral flow microarray assay for detection of citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis pv citri

    Energy Technology Data Exchange (ETDEWEB)

    Cary; R. Bruce (Santa Fe, NM); Stubben, Christopher J. (Los Alamos, NM)

    2011-03-22

    The invention provides highly sensitive and specific assays for the major citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis, including a field deployable multiplexed assay capable of rapidly assaying for both pathogens simultaneously. The assays are directed at particular gene targets derived from pathogenic strains that specifically cause the major citrus diseases of citrus variegated chlorosis (Xylella fastidiosa 9a5c) and citrus canker (Xanthomonas axonopodis pv citri). The citrus pathogen assays of the invention offer femtomole sensitivity, excellent linear dynamic range, and rapid and specific detection.

  5. Tomato early blight (Alternaria solani): the pathogen, genetics and breeding for resistance

    OpenAIRE

    Chaerani, R.; Voorrips, R. E.

    2006-01-01

    Alternaria solani causes diseases on foliage (early blight), basal stems of seedlings (collar rot), stems of adult plants (stem lesions), and fruits (fruit rot) of tomato. Early blight is the most destructive of these diseases and hence receives considerable attention in breeding. For over 60 years, breeding for early blight resistance has been practiced, but the development of cultivars with high levels of resistance has been hampered by the lack of sources of strong resistance in the cultiv...

  6. Characterization and Pathogenicity of Alternaria burnsii from Seeds of Cucurbita maxima (Cucurbitaceae) in Bangladesh.

    Science.gov (United States)

    Paul, Narayan Chandra; Deng, Jian Xin; Lee, Hyang Burm; Yu, Seung-Hun

    2015-12-01

    In the course of survey of endophytic fungi from Bangladesh pumpkin seeds in 2011~2012, two strains (CNU111042 and CNU111043) with similar colony characteristics were isolated and characterized by their morphology and by molecular phylogenetic analysis of the internal transcribed spacer, glyceraldehydes-3-phosphate dehydrogenase (gpd), and Alternaria allergen a1 (Alt a1) sequences. Phylogenetic analysis of all three sequences and their combined dataset revealed that the fungus formed a subclade within the A. alternata clade, matching A. burnsi and showing differences with its other closely related Alternaria species, such as A. longipes, A. tomato, and A. tomaticola. Long ellipsoid, obclavate or ovoid beakless conidia, shorter and thinner conidial size (16~60 [90] × 6.5~14 [~16] µm) distinguish this fungus from other related species. These isolates showed more transverse septation (2~11) and less longitudinal septation (0~3) than did other related species. Moreover, the isolate did not produce any diffusible pigment on media. Therefore, our results reveal that the newly recorded fungus from a new host, Cucurbita maxima, is Alternaria burnsii Uppal, Patel & Kamat.

  7. Environmental Factors Affecting Production, Release, and Field Populations of Conidia of Alternaria alternata, the Cause of Brown Spot of Citrus.

    Science.gov (United States)

    Timmer, L W; Solel, Z; Gottwald, T R; Ibañez, A M; Zitko, S E

    1998-11-01

    ABSTRACT Alternaria brown spot, caused by Alternaria alternata pv. citri, affects many tangerines and their hybrids, causing loss of immature leaves and fruit and reducing the marketability of the remaining fruit. Conidial production of A. alternata was greatest on mature leaves moistened and maintained at near 100% relative humidity (RH) for 24 h, whereas leaves that had been soaked or maintained at moderate RH produced few conidia. Conidial release from filter paper cultures and infected leaves was studied in a computer-controlled environmental chamber. Release of large numbers of conidia was triggered from both substrates by sudden drops in RH or by simulated rainfall events. Vibration induced release of low numbers of conidia, but red/infrared irradiation had no effect. In field studies from 1994 to 1996, air sampling with a 7-day recording volumetric spore trap indicated that conidia were present throughout the year with periodic large peaks. The number of conidia captured was not closely related to rainfall amounts or average wind speed, but was weakly related to the duration of leaf wetness. Likewise, disease severity on trap plants placed in the field weekly during 1995 to 1996 was not closely related to conidial numbers or rainfall amounts, but was weakly related to leaf wetness duration. Sufficient inoculum appears to be available to allow infection to occur throughout the year whenever susceptible host tissue and moisture are available.

  8. Biology and management of Asian citrus psyllid, vector of the huanglongbing pathogens.

    Science.gov (United States)

    Grafton-Cardwell, Elizabeth E; Stelinski, Lukasz L; Stansly, Philip A

    2013-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the most important pest of citrus worldwide because it serves as a vector of "Candidatus Liberibacter" species (Alphaproteobacteria) that cause huanglongbing (citrus greening disease). All commercially cultivated citrus is susceptible and varieties tolerant to disease expression are not yet available. Onset of disease occurs following a long latent period after inoculation, and thus the pathogen can spread widely prior to detection. Detection of the pathogen in Brazil in 2004 and Florida in 2005 catalyzed a significant increase in research on D. citri biology. Chemical control is the primary management strategy currently employed, but recently documented decreases in susceptibility of D. citri to several insecticides illustrate the need for more sustainable tools. Herein, we discuss recent advances in the understanding of D. citri biology and behavior, pathogen transmission biology, biological control, and chemical control with respect to "Candidatus Liberibacter asiaticus." Our goal is to point toward integrated and biologically relevant management of this pathosystem.

  9. Determination of the Presence of Huanglongbing in Seeds and Movement of the Pathogen in Citrus reticulata

    Directory of Open Access Journals (Sweden)

    Hajivand Shokrollah

    2009-01-01

    Full Text Available Problem statement: Huanglongbing (HLB also known as citrus greening disease is a fastidious phloem-inhabiting bacterium in the genus Candidatus Liberibacter. Using universal primers, the 16S ribosomal DNA sequence of three strains of the bacterium were obtained by PCR. However there is very little information on seed transmission and HLB pathogen movement to find a way for control or reduce the severity of HLB on the field. The study was conducted to detect HLB pathogen in seeds of Citrus, to determine pathogen movement in citrus seedling after infection and to detect the HLB pathogen in citrus roots. Approach: Seeds of Citrus reticulata cv. Limau Madu were collected from infected orchard and were germinated in screenhouse condition. The seeds of Citrus reticlata cv. L. Madu were planted in screenhouse too for HLB pathogen movement and HLB detection in roots. The seedlings were inoculated using infected grafting methods. Results: HLB was not amplified in new seedlings after germination. HLB moved slowly reaching up to 1.5 cm after 2 weeks, 1.5-4.5 cm after eight weeks and detected on 4.5-9 cm after 14 weeks below the grafting area. HLB was also detected up to 9-15 cm after 16 weeks, 15-24 cm after twenty weeks, 24-28.5 cm after 22 weeks and 28.5-30 cm after 24 weeks below the grafting area. Conclusion: Base on conventional PCR test, HLB disease in citrus is not seed borne and it can reach to the roots 26 weeks after inoculation.

  10. Fungal-specific transcription factor AbPf2 activates pathogenicity in Alternaria brassicicola

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yangrae; Ohm, Robin A. [US Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA; Grigoriev, Igor V. [US Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA; Srivastava, Akhil [Plant and Environmental Protection Sciences, University of Hawaii at Manoa, 3190 Maile Way, St John 317, Honolulu, HI, 96822, USA

    2013-05-24

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. To identify molecular determinants of pathogenicity, we created non-pathogenic mutants of a transcription factor-encoding gene, AbPf2. The frequency and timing of germination and appressorium formation on host plants were similar between the non-pathogenic abpf2 mutants and wild-type A. brassicicola. The mutants were also similar in vitro to wild-type A. brassicicola in terms of vegetative growth, conidium production, and responses to a phytoalexin, reactive oxygen species and osmolites. The hyphae of the mutants grew slowly but did not cause disease symptoms on the surface of host plants. Transcripts of the AbPf2 gene increased exponentially soon after wild-type conidia contacted their host plants . A small amount of AbPf2 protein, as monitored using GFP fusions, was present in young, mature conidia. The protein level decreased during saprophytic growth, but increased and was located primarily in fungal nuclei during pathogenesis. Levels of the proteins and transcripts sharply decreased following colonization of host tissues beyond the initial infection site. When expression of the transcription factor was induced in the wild-type during early pathogenesis, 106 fungal genes were also induced in the wild-type but not in the abpf2 mutants. Notably, 33 of the 106 genes encoded secreted proteins, including eight putative effector proteins. Plants inoculated with abpf2 mutants expressed higher levels of genes associated with photosynthesis, the pentose phosphate pathway and primary metabolism, but lower levels of defense-related genes. Our results suggest that AbPf2 is an important regulator of pathogenesis, but does not affect other cellular processes in A. brassicicola.

  11. Functional Analyses of the Diels-Alderase Gene sol5 of Ascochyta rabiei and Alternaria solani Indicate that the Solanapyrone Phytotoxins Are Not Required for Pathogenicity.

    Science.gov (United States)

    Kim, Wonyong; Park, Chung-Min; Park, Jeong-Jin; Akamatsu, Hajime O; Peever, Tobin L; Xian, Ming; Gang, David R; Vandemark, George; Chen, Weidong

    2015-04-01

    Ascochyta rabiei and Alternaria solani, the causal agents of Ascochyta blight of chickpea (Cicer arietinum) and early blight of potato (Solanum tuberosum), respectively, produce a set of phytotoxic compounds including solanapyrones A, B, and C. Although both the phytotoxicity of solanapyrones and their universal production among field isolates have been documented, the role of solanapyrones in pathogenicity is not well understood. Here, we report the functional characterization of the sol5 gene, which encodes a Diels-Alderase that catalyzes the final step of solanapyrone biosynthesis. Deletion of sol5 in both Ascochyta rabiei and Alternaria solani completely prevented production of solanapyrones and led to accumulation of the immediate precursor compound, prosolanapyrone II-diol, which is not toxic to plants. Deletion of sol5 did not negatively affect growth rate or spore production in vitro, and led to overexpression of the other solanapyrone biosynthesis genes, suggesting a possible feedback regulation mechanism. Phytotoxicity tests showed that solanapyrone A is highly toxic to several legume species and Arabidopsis thaliana. Despite the apparent phytotoxicity of solanapyrone A, pathogenicity tests showed that solanapyrone-minus mutants of Ascochyta rabiei and Alternaria solani were equally virulent as their corresponding wild-type progenitors, suggesting that solanapyrones are not required for pathogenicity.

  12. Draft Genome Sequence of 11399, a Transformable Citrus-Pathogenic Strain of Xylella fastidiosa

    OpenAIRE

    Niza, Bárbara; Merfa, Marcus V.; Alencar, Valquíria C.; Menegidio, Fabiano B.; Nunes, Luiz R.; Machado, Marcos A.; Takita,Marco A.; Souza,Alessandra A. de

    2016-01-01

    The draft genome of Xylella fastidiosa subsp. pauca strain 11399, a transformable citrus-pathogenic strain, is reported here. The 11399 genome size is 2,690,704 bp and has a G+C content of 52.7%. The draft genome of 11399 reveals the absence of four type I restriction-modification system genes.

  13. Citrus phenylpropanoids and defence against pathogens. Part I: Metabolic profiling in elicited fruits

    NARCIS (Netherlands)

    Ballester, A.R.; Lafuente, M.T.; Vos, de R.C.H.; Bovy, A.G.; González-Candelas, L.

    2013-01-01

    Penicillium spp. are among the major postharvest pathogens of citrus fruit. Induction of natural resistance in fruits constitutes one of the alternatives to chemical fungicides. Here, we investigated the involvement of the phenylpropanoid pathway in the induction of resistance in Navelate oranges by

  14. Draft Genome Sequence of 11399, a Transformable Citrus-Pathogenic Strain of Xylella fastidiosa

    Science.gov (United States)

    Niza, Bárbara; Merfa, Marcus V.; Alencar, Valquíria C.; Menegidio, Fabiano B.; Nunes, Luiz R.; Machado, Marcos A.; Takita, Marco A.

    2016-01-01

    The draft genome of Xylella fastidiosa subsp. pauca strain 11399, a transformable citrus-pathogenic strain, is reported here. The 11399 genome size is 2,690,704 bp and has a G+C content of 52.7%. The draft genome of 11399 reveals the absence of four type I restriction-modification system genes. PMID:27738038

  15. Inhibitory activity of Indian spice plant Cinnamomum zeylanicum extracts against Alternaria solani and Curvularia lunata, the pathogenic dematiaceous moulds

    Directory of Open Access Journals (Sweden)

    Sharma Bechan

    2009-03-01

    Full Text Available Abstract Background Dematiaceous moulds are pathogenic microorganisms and act as etiological agents of mycoses with different degrees of severity in humans and animals. These moulds also cause loss of food crops and storage food products. The information regarding antimicrobial efficacy of the plant preparations on these moulds is scanty. The present study reveals phytochemical characterization and the effect of bark and leaf extracts of Indian spice plant, Cinnamomum zeylanicum (Cz, against the growth of two species of dematiaceous moulds, Alternaria solani and Curvularia lunata. Methods Cz bark and leaf samples were sequentially extracted in different solvents using Soxhlet apparatus. Phytochemical analyses of extracts were done as per standard protocols. The antifungal bioassay of extracts was done by hanging drop technique. The inhibition of fungal spore germination was monitored under influence of three different concentrations of extracts. Results The lowest test concentration (50 μg/ml of extracts of Cz bark prepared into acetone and that of Cz leaf into petroleum ether and ethanol exhibited complete inhibition (100% of spore germination in both the moulds. At 100 μg/ml concentration all the extracts showed about 50 to 100% inhibition. However, the treatment of the spores of the two fungal species with highest concentration (500 μg/ml of bark and leaf extracts in all the solvents showed 100% fungicidal activity as it completely arrested the germination of spores. Relatively lower activity of aqueous extracts at 50 and 100 μg/ml concentrations suggests that the antifungal ingredients present in Cz bark and leaf are more soluble in organic solvents than water. Conclusion The results demonstrated that the Cz bark and leaves contain certain fungicidal constituents exhibiting potential antimould activity against A. solani and C. lunata.

  16. Inhibitory activity of Indian spice plant Cinnamomum zeylanicum extracts against Alternaria solani and Curvularia lunata, the pathogenic dematiaceous moulds.

    Science.gov (United States)

    Mishra, Ajay K; Mishra, Amita; Kehri, H K; Sharma, Bechan; Pandey, Abhay K

    2009-03-07

    Dematiaceous moulds are pathogenic microorganisms and act as etiological agents of mycoses with different degrees of severity in humans and animals. These moulds also cause loss of food crops and storage food products. The information regarding antimicrobial efficacy of the plant preparations on these moulds is scanty. The present study reveals phytochemical characterization and the effect of bark and leaf extracts of Indian spice plant, Cinnamomum zeylanicum (Cz), against the growth of two species of dematiaceous moulds, Alternaria solani and Curvularia lunata. Cz bark and leaf samples were sequentially extracted in different solvents using Soxhlet apparatus. Phytochemical analyses of extracts were done as per standard protocols. The antifungal bioassay of extracts was done by hanging drop technique. The inhibition of fungal spore germination was monitored under influence of three different concentrations of extracts. The lowest test concentration (50 microg/ml) of extracts of Cz bark prepared into acetone and that of Cz leaf into petroleum ether and ethanol exhibited complete inhibition (100%) of spore germination in both the moulds. At 100 microg/ml concentration all the extracts showed about 50 to 100% inhibition. However, the treatment of the spores of the two fungal species with highest concentration (500 microg/ml) of bark and leaf extracts in all the solvents showed 100% fungicidal activity as it completely arrested the germination of spores. Relatively lower activity of aqueous extracts at 50 and 100 microg/ml concentrations suggests that the antifungal ingredients present in Cz bark and leaf are more soluble in organic solvents than water. The results demonstrated that the Cz bark and leaves contain certain fungicidal constituents exhibiting potential antimould activity against A. solani and C. lunata.

  17. PATHOGENIC BEHAVIOUR OF ALTERNARIA ALTERNATA AND PHYTOTOXICITY OF ITS CULTURE FILTRATES ON LEPIDIUM SATIVUM: A MEDICINAL HERB OF IMMENSE PHARMACOLOGICAL POTENTIAL

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    U. K. KHARE

    2013-01-01

    Full Text Available Alternaria alternata causing leaf spot in Lepidium sativum was isolated and purified from diseased leaf tissuescollected from collected from the Medicinal and Aromatic plant garden, Department of Crop and HerbalPhysiology, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (M.P.; isolated and purified on Potato DextroseAgar media. Microscopic examination of a seven days old culture revealed hyaline, septate and branched mycelia,conidiophores with 30.0-80.2 µ length and 3-6 µ width and obclavate to obpyriform conidia (23-30 x 9.2-12.7µ with short conical beak arranged in acropetal fashion. The isolated culture and its culture filtrates wereinoculated to germinated seedlings of chandrasur and also incubated with healthy leaves in a growth chamber.Typical symptoms of Alternaria leaf spot was observed both in in vivo and in vitro inoculated plantlets anddetached leaves respectively. Chlorosis on the hypocotyls and leaves were observed. A. alternata was consistentlyreisolated from symptomatic leaf tissues on PDA. Thus, an efficient and reliable screening method wherein theeffect of the selection agent (pathogen culture, culture filtrate/phytotoxin was demonstrated providing soundpharmacological rational in terms of micro propagation and development of Alternaria resistant L. sativum, animportant medicinal herb.

  18. STUDIES ON ANTIMICROBIAL ACTIVITY AND PHYTOCHEMICAL ANALYSIS OF CITRUS FRUIT JUICES AGAINST SELECTED ENTERIC PATHOGENS

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    Bansode.D.S.

    2012-11-01

    Full Text Available The present study was carried out to find out the antimicrobial activity and phytochemical study of citrus fruit juices viz. Lemon (Citrus limon and Orange (Citrus ourantium against medically important selected enteric pathogens. As microorganisms are becoming resistant to present day antibiotics, our study focuses on antimicrobial activity and phytochemical study of Citrus fruit juices against selected enteric pathogens. Biological active compounds present in the medicinal important fruit juices have always been of great interest to scientist. These compounds, not only play an important physiological and etiological role, but are also of commercial interest because of their multitude application in the food and pharmaceutical industries. In the present study, the Lemon and Orange fruit juices were subjected to screening against enteric pathogens, E.coli, Salmonella paratyphy B, and Shigella sonnei. Antimicrobial analysis was done by using agar well diffusion method against selected enteric bacteria. The MIC values were determined by using U.V. Spectrophotometer. The fresh crude Lemon fruit juice produced the highest antimicrobial activity against Salmonella para.B and Shigella sonnei followed by E.coli and fresh crude Orange fruit juice produced the highest antimicrobial activity against Shigella sonnei and Salmonella para.B. followed by E.coli. The antimicrobial activity of standard antibiotic Ampicillin was studied in comparison with Lemon and Orange fruit juices. The Minimum inhibitory concentration observed at 25% conc. of lemon juice against Salmonella paratyphy B, and Shigella sonnei and 25% concentration of orange juice against Shigella sonnei. The phytochemical analysis showed the presence of phenols, flavonoids, glycosides, steroid, saponin, and reducing sugar in citrus fruit juices.

  19. Most AAL toxin-sensitive Nicotiana species are resistant to the tomato fungal pathogen Alternaria alternata f. sp lycopersici

    NARCIS (Netherlands)

    Brandwagt, Bas F.; Kneppers, Tarcies J.A.; Weerden, Gerard M. van der; Nijkamp, H. John J.; Hille, Jacques

    2001-01-01

    The phytopathogenic fungus Alternaria alternata f. sp, lycopersici produces AAL toxins required to colonize susceptible tomato (Lycopersicon esculentum) plants, AAL toxins and fumonisins of the unrelated fungus Fusarium moniliforme are sphinganine-analog mycotoxins (SAMs), which are toxic for some p

  20. Multilocus phylogeny and MALDI-TOF analysis of the plant-pathogenic species Alternaria dauci and relatives

    NARCIS (Netherlands)

    Brun, S.; Madrid, H.; Gerrits van den Ende, A.H.G.; Andersen, B.; Marinach-Patrice, C.; Mazier, D.; de Hoog, G.S.

    2013-01-01

    The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of morphol

  1. Arabidopsis Elongator subunit 2 positively contributes to resistance to the necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola.

    Science.gov (United States)

    Wang, Chenggang; Ding, Yezhang; Yao, Jin; Zhang, Yanping; Sun, Yijun; Colee, James; Mou, Zhonglin

    2015-09-01

    The evolutionarily conserved Elongator complex functions in diverse biological processes including salicylic acid-mediated immune response. However, how Elongator functions in jasmonic acid (JA)/ethylene (ET)-mediated defense is unknown. Here, we show that Elongator is required for full induction of the JA/ET defense pathway marker gene PLANT DEFENSIN1.2 (PDF1.2) and for resistance to the necrotrophic fungal pathogens Botrytis cinerea and Alternaria brassicicola. A loss-of-function mutation in the Arabidopsis Elongator subunit 2 (ELP2) alters B. cinerea-induced transcriptome reprogramming. Interestingly, in elp2, expression of WRKY33, OCTADECANOID-RESPONSIVE ARABIDOPSIS AP2/ERF59 (ORA59), and PDF1.2 is inhibited, whereas transcription of MYC2 and its target genes is enhanced. However, overexpression of WRKY33 or ORA59 and mutation of MYC2 fail to restore PDF1.2 expression and B. cinerea resistance in elp2, suggesting that ELP2 is required for induction of not only WRKY33 and ORA59 but also PDF1.2. Moreover, elp2 is as susceptible as coronatine-insensitive1 (coi1) and ethylene-insensitive2 (ein2) to B. cinerea, indicating that ELP2 is an important player in B. cinerea resistance. Further analysis of the lesion sizes on the double mutants elp2 coi1 and elp2 ein2 and the corresponding single mutants revealed that the function of ELP2 overlaps with COI1 and is additive to EIN2 for B. cinerea resistance. Finally, basal histone acetylation levels in the coding regions of WRKY33, ORA59, and PDF1.2 are reduced in elp2 and a functional ELP2-GFP fusion protein binds to the chromatin of these genes, suggesting that constitutive ELP2-mediated histone acetylation may be required for full activation of the WRKY33/ORA59/PDF1.2 transcriptional cascade.

  2. Metabolites from Alternaria Fungi and Their Bioactivities

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    Ligang Zhou

    2013-05-01

    Full Text Available Alternaria is a cosmopolitan fungal genus widely distributing in soil and organic matter. It includes saprophytic, endophytic and pathogenic species. At least 268 metabolites from Alternaria fungi have been reported in the past few decades. They mainly include nitrogen-containing metabolites, steroids, terpenoids, pyranones, quinones, and phenolics. This review aims to briefly summarize the structurally different metabolites produced by Alternaria fungi, as well as their occurrences, biological activities and functions. Some considerations related to synthesis, biosynthesis, production and applications of the metabolites from Alternaria fungi are also discussed.

  3. Responsiveness of different citrus genotypes to the Xanthomonas citri ssp. citri-derived pathogen-associated molecular pattern (PAMP) flg22 correlates with resistance to citrus canker.

    Science.gov (United States)

    Shi, Qingchun; Febres, Vicente J; Jones, Jeffrey B; Moore, Gloria A

    2015-06-01

    The bacterial agent of citrus canker disease (Xanthomonas citri ssp. citri, Xcc) has caused tremendous economic losses to the citrus industry around the world. Pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is important to plant immunity. In this study, we compared the defence responses of citrus canker-resistant and citrus canker-susceptible genotypes to the Xcc-derived PAMP flg22 (Xflg22) by analysing the expression of 20 citrus defence-associated genes. We showed that, in the most resistant genotype, 'Nagami' kumquat, there was significant induction of several defence genes (EDS1, NDR1, PBS1, RAR1, SGT1, PAL1, NPR2 and NPR3) as early as 6 h and up to 72 h after Xflg22 treatment. At the other end of the spectrum, highly susceptible 'Duncan' grapefruit showed no induction of the same defence genes, even 120 h after treatment. Citrus genotypes with partial levels of resistance showed intermediate levels of transcriptional reprogramming that correlated with their resistance level. Xflg22 also triggered a rapid oxidative burst in all genotypes which was higher and accompanied by the induction of PTI marker genes (WRKY22 and GST1) only in the more resistant genotypes. Pretreatment with Xflg22 prior to Xcc inoculation inhibited bacterial growth in kumquat, but not in grapefruit. A flagellin-deficient Xcc strain (XccΔfliC) showed greater growth increase relative to wild-type Xcc in kumquat than in grapefruit. Taken together, our results indicate that Xflg22 initiates strong PTI in canker-resistant genotypes, but not in susceptible ones, and that a robust induction of PTI is an important component of citrus resistance to canker.

  4. Validation of high-throughput real time polymerase chain reaction assays for simultaneous detection of invasive citrus pathogens.

    Science.gov (United States)

    Saponari, Maria; Loconsole, Giuliana; Liao, Hui-Hong; Jiang, Bo; Savino, Vito; Yokomi, Raymond K

    2013-11-01

    A number of important citrus pathogens are spread by graft propagation, arthropod vector transmission and inadvertent import and dissemination of infected plants. For these reasons, citrus disease management and clean stock programs require pathogen detection systems which are economical and sensitive to maintain a healthy industry. To this end, multiplex quantitative real-time PCR (qPCR) assays were developed allowing high-throughput and simultaneous detection of some major invasive citrus pathogens. Automated high-throughput extraction comparing several bead-based commercial extraction kits were tested and compared with tissue print and manual extraction to obtain nucleic acids from healthy and pathogen-infected citrus trees from greenhouse in planta collections and field. Total nucleic acids were used as templates for pathogen detection. Multiplex reverse transcription-qPCR (RT-qPCR) assays were developed for simultaneous detection of six targets including a virus, two viroids, a bacterium associated with huanglongbing and a citrus RNA internal control. Specifically, two one-step TaqMan-based multiplex RT-qPCR assays were developed and tested with target templates to determine sensitivity and detection efficiency. The first assay included primers and probes for 'Candidatus Liberibacter asiaticus' (CLas) and Citrus tristeza virus (CTV) broad spectrum detection and genotype differentiation (VT- and T3-like genotypes). The second assay contained primers and probes for Hop stunt viroid (HSVd), Citrus exocortis viroid (CEVd) and the mitochondrial NADH dehydrogenase (nad5) mRNA as an internal citrus host control. Primers and TaqMan probes for the viroids were designed in this work; whereas those for the other pathogens were from reports of others. Based on quantitation cycle values, automated high-throughput extraction of samples proved to be as suitable as manual extraction. The multiplex RT-qPCR assays detected both RNA and DNA pathogens in the same dilution series

  5. Synthesis of Oxylipin Mimics and Their Antifungal Activity against the Citrus Postharvest Pathogens

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    Jimei Ma

    2016-02-01

    Full Text Available Nine oxylipin mimics were designed and synthesized starting from d-mannose. Their antifungal activity against three citrus postharvest pathogens was evaluated by spore germination assay. The results indicated that all the compounds significantly inhibited the growth of Penicillium digitatum, Penicillium italicum and Aspergillus niger. The compound (3Z,6Z,8S,9R,10R-octadeca-3,6-diene-8,9,10-triol (3 exhibited excellent inhibitory effect on both Penicillium digitatum (IC50 = 34 ppm and Penicillium italicum (IC50 = 94 ppm. Their in vivo antifungal activities against citrus postharvest blue mold were tested with fruit inoculated with the pathogen Penicillium italicum. The compound (3R,4S-methyl 3,4-dihydroxy-5-octyltetrahydrofuran-2-carboxylate (9 demonstrated significant efficacy by reducing the disease severity to 60%. The antifungal mechanism of these oxylipin mimics was postulated in which both inhibition of pathogenic mycelium and stimuli of the host oxylipin-mediated defense response played important roles.

  6. Prophage-mediated dynamics of 'Candidatus Liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.

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    Lijuan Zhou

    Full Text Available Prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. There are at least two prophages in the chromosomes of Candidatus Liberibacter asiaticus' (Las Floridian isolates. Las is both unculturable and the most prevalent species of Liberibacter pathogens that cause huanglongbing (HLB, a worldwide destructive disease of citrus. In this study, seven new prophage variants resulting from two hyper-variable regions were identified by screening clone libraries of infected citrus, periwinkle and psyllids. Among them, Types A and B share highly conserved sequences and localize within the two prophages, FP1 and FP2, respectively. Although Types B and C were abundant in all three libraries, Type A was much more abundant in the libraries from the Las-infected psyllids than from the Las-infected plants, and Type D was only identified in libraries from the infected host plants but not from the infected psyllids. Sequence analysis of these variants revealed that the variations may result from recombination and rearrangement events. Conventional PCR results using type-specific molecular markers indicated that A, B, C and D are the four most abundant types in Las-infected citrus and periwinkle. However, only three types, A, B and C are abundant in Las-infected psyllids. Typing results for Las-infected citrus field samples indicated that mixed populations of Las bacteria present in Floridian isolates, but only the Type D population was correlated with the blotchy mottle symptom. Extended cloning and sequencing of the Type D region revealed a third prophage/phage in the Las genome, which may derive from the recombination of FP1 and FP2. Dramatic variations in these prophage regions were also found among the global Las isolates. These results are the first to demonstrate the prophage/phage-mediated dynamics of Las populations in plant and insect hosts, and their correlation with insect transmission and

  7. Prophage-mediated dynamics of 'Candidatus Liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.

    Science.gov (United States)

    Zhou, Lijuan; Powell, Charles A; Li, Wenbin; Irey, Mike; Duan, Yongping

    2013-01-01

    Prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. There are at least two prophages in the chromosomes of Candidatus Liberibacter asiaticus' (Las) Floridian isolates. Las is both unculturable and the most prevalent species of Liberibacter pathogens that cause huanglongbing (HLB), a worldwide destructive disease of citrus. In this study, seven new prophage variants resulting from two hyper-variable regions were identified by screening clone libraries of infected citrus, periwinkle and psyllids. Among them, Types A and B share highly conserved sequences and localize within the two prophages, FP1 and FP2, respectively. Although Types B and C were abundant in all three libraries, Type A was much more abundant in the libraries from the Las-infected psyllids than from the Las-infected plants, and Type D was only identified in libraries from the infected host plants but not from the infected psyllids. Sequence analysis of these variants revealed that the variations may result from recombination and rearrangement events. Conventional PCR results using type-specific molecular markers indicated that A, B, C and D are the four most abundant types in Las-infected citrus and periwinkle. However, only three types, A, B and C are abundant in Las-infected psyllids. Typing results for Las-infected citrus field samples indicated that mixed populations of Las bacteria present in Floridian isolates, but only the Type D population was correlated with the blotchy mottle symptom. Extended cloning and sequencing of the Type D region revealed a third prophage/phage in the Las genome, which may derive from the recombination of FP1 and FP2. Dramatic variations in these prophage regions were also found among the global Las isolates. These results are the first to demonstrate the prophage/phage-mediated dynamics of Las populations in plant and insect hosts, and their correlation with insect transmission and disease development.

  8. 柑桔园链格孢菌Mp3毒素作用机制研究%Action Mechanism of Alternaria sp.Mp3 Toxin in Citrus

    Institute of Scientific and Technical Information of China (English)

    刘荣萍; 刘娟; 胡军华; 姚廷山; 李鸿筠; 冉春; 刘浩强

    2012-01-01

    Crude toxin was extracted from Alternaria sp. Mp3 to test for allergenic reaction and color reaction to characterize the toxin in citrus. The content of malondialdehyde (MDA) and the activities of peroxidase (POD) and ascorbate peroxidase (APX) in leaves of Carrizo citrange were measured following treatment with the crude toxia Color reaction showed that Mp3 toxin was ketone. similar to ACT toxin produced by A. citri. The POD and APX activities were reduced in leaves treated with Mp3 toxin, but the MDA content was increased. These suggested that Mp3 toxin inhibited the activities of protective enzymes, and damaged the capability of cells to scavenge reactive oxygen species, resulting in accumulation of reactive oxygen species that caused the oxidization of plasma membrane. It was found that the increase in MDA content following the treatment of Mp3 toxin was dependent on dosages of the toxin applied and that the target site of Mp3 toxin, like ACT toxin, was plasma membrane. The results of the study would be used as references in identification and control of Alternaria fungi in citrus orchards.%为了明确柑桔园链格孢菌Mp3(Alternaria sp.)毒素的作用机制,在试验条件下提取菌株Mp3的粗毒素进行致敏性反应和显色反应,并测定粗毒素处理的卡里佐枳橙幼苗叶片的丙二醛( MDA)含量及过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性.结果发现,链格孢菌Mp3的毒素为酮类物质,与已经报道的A,citri产生的ACT毒素相似.Mp3的毒素处理后,卡里佐枳橙叶片的MDA含量升高,POD、APX活性最终下降,说明Mp3的毒素能够抑制卡里佐枳橙叶片的保护性酶系统,细胞内活性氧清除系统遭到破坏.导致活性氧大量积累,使质膜发生过氧化反应,产生MDA,而且MDA含量随着Mp3毒素浓度的增加而增加.证明Mp3毒素的作用位点为质膜,这与ACT毒素的作用位点一致.此研究为柑桔园中链格孢菌的鉴定和防治提供了参考.

  9. The destructive citrus pathogen, 'Candidatus Liberibacter asiaticus' encodes a functional flagellin characteristic of a pathogen-associated molecular pattern.

    Directory of Open Access Journals (Sweden)

    Huasong Zou

    Full Text Available Huanglongbing (HLB is presently the most devastating citrus disease worldwide. As an intracellular plant pathogen and insect symbiont, the HLB bacterium, 'Candidatus Liberibacter asiaticus' (Las, retains the entire flagellum-encoding gene cluster in its significantly reduced genome. Las encodes a flagellin and hook-associated protein (Fla of 452 amino acids that contains a conserved 22 amino acid domain (flg22 at positions 29 to 50 in the N-terminus. The phenotypic alteration in motility of a Sinorhizobium meliloti mutant lacking the fla genes was partially restored by constitutive expression of Fla(Las. Agrobacterium-mediated transient expression in planta revealed that Fla(Las induced cell death and callose deposition in Nicotiana benthamiana, and that the transcription of BAK1 and SGT1, which are associated with plant innate immunity, was upregulated. Amino acid substitution experiments revealed that residues 38 (serine and 39 (aspartate of Fla(Las were essential for callose induction. The synthetic flg22(Las peptide could not induce plant cell death but retained the ability to induce callose deposition at a concentration of 20 µM or above. This demonstrated that the pathogen-associated molecular pattern (PAMP activity of flg22 in Las was weaker than those in other well-studied plant pathogenic bacteria. These results indicate that Fla(Las acts as a PAMP and may play an important role in triggering host plant resistance to the HLB bacteria.

  10. Insecticidal suppression of Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae) vector of huanglongbing pathogens.

    Science.gov (United States)

    Qureshi, Jawwad A; Kostyk, Barry C; Stansly, Philip A

    2014-01-01

    Diaphorina citri vectors pathogens that cause 'huanglongbing' or citrus greening disease which poses a serious threat to citrus production worldwide. Vector suppression is critical to reduce disease spread. Efficacy is a main concern when choosing an insecticide. Insecticidal treatments of 49 products or 44 active ingredients (a.i) labeled or experimental were field tested between 2005-2013 as foliar sprays (250 treatments, 39 a.i) or soil applications (47 treatments, 9 a.i) to control D. citri in citrus. A combined effect of nymphal and adult suppression in response to sprays of 23 insecticides representing 9 modes of action (MoA) groups and 3 unknown MoA provided more than 90% reduction of adult D. citri over 24-68 days. Observable effects on nymphs were generally of shorter duration due to rapid maturation of flush. However, reduction of 76-100% nymphs or adults over 99-296 days was seen on young trees receiving drenches of the neonicotinoids imidacloprid, thiamethoxam or clothianidin (MoA 4A) and a novel anthranilic diamide, cyantraniliprole (MoA 28). Effective products identified for foliar sprays to control D. citri provide sufficient MoA groups for rotation to delay evolution of insecticide resistance by D. citri and other pests. However, cyantraniliprole is now the only available alternative for rotation with neonicotinoids in soil application to young trees. Sprays of up to eight of the most effective insecticides could be rotated over a year without repetition of any MoA and little or no recourse to neonicotinoids or cyantraniliprole, so important for protection of young trees. Other considerations effecting decisions of what and when to spray include prevalence of huanglongbing, pest pressure, pre-harvest intervals, overall budget, equipment availability, and conservation of beneficial arthropods. Examples of spray programs utilizing broad-spectrum and relatively selective insecticides are provided to improve vector management and may vary depending on

  11. Insecticidal suppression of Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae vector of huanglongbing pathogens.

    Directory of Open Access Journals (Sweden)

    Jawwad A Qureshi

    Full Text Available Diaphorina citri vectors pathogens that cause 'huanglongbing' or citrus greening disease which poses a serious threat to citrus production worldwide. Vector suppression is critical to reduce disease spread. Efficacy is a main concern when choosing an insecticide. Insecticidal treatments of 49 products or 44 active ingredients (a.i labeled or experimental were field tested between 2005-2013 as foliar sprays (250 treatments, 39 a.i or soil applications (47 treatments, 9 a.i to control D. citri in citrus. A combined effect of nymphal and adult suppression in response to sprays of 23 insecticides representing 9 modes of action (MoA groups and 3 unknown MoA provided more than 90% reduction of adult D. citri over 24-68 days. Observable effects on nymphs were generally of shorter duration due to rapid maturation of flush. However, reduction of 76-100% nymphs or adults over 99-296 days was seen on young trees receiving drenches of the neonicotinoids imidacloprid, thiamethoxam or clothianidin (MoA 4A and a novel anthranilic diamide, cyantraniliprole (MoA 28. Effective products identified for foliar sprays to control D. citri provide sufficient MoA groups for rotation to delay evolution of insecticide resistance by D. citri and other pests. However, cyantraniliprole is now the only available alternative for rotation with neonicotinoids in soil application to young trees. Sprays of up to eight of the most effective insecticides could be rotated over a year without repetition of any MoA and little or no recourse to neonicotinoids or cyantraniliprole, so important for protection of young trees. Other considerations effecting decisions of what and when to spray include prevalence of huanglongbing, pest pressure, pre-harvest intervals, overall budget, equipment availability, and conservation of beneficial arthropods. Examples of spray programs utilizing broad-spectrum and relatively selective insecticides are provided to improve vector management and may vary

  12. Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri

    Science.gov (United States)

    Nanda, Satyabrata; Chand, Subodh Kumar; Mandal, Purander; Tripathy, Pradyumna; Joshi, Raj Kumar

    2016-01-01

    Purple blotch, caused by Alternaria porri (Ellis) Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession ‘CBT-Ac77’ and cultivar ‘Arka Kalyan’ were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri, revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur) in 43 genotypes revealed significant variation among the evaluated Allium species (P = 0.001). All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India. PMID:27904458

  13. Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis Ciferri

    Directory of Open Access Journals (Sweden)

    Satyabrata Nanda

    2016-12-01

    Full Text Available Purple blotch, caused by Alternaria porri (Ellis Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession ‘CBT-Ac77’ and cultivar ‘Arka Kalyan’ were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri, revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur in 43 genotypes revealed significant variation among the evaluated Allium species (P = 0.001. All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India.

  14. Induction of protection against the necrotrophic pathogens Phytophthora citrophthora and Alternaria solani in Lycopersicon esculentum Mill. by a novel synthetic glycoside combined with amines.

    Science.gov (United States)

    Flors, Víctor; Miralles, M Carmen; González-Bosch, Carmen; Carda, Miguel; García-Agustín, Pilar

    2003-04-01

    1,2,3,4-tetra-O-acetyl-6-ethyladipate-beta- D-glucopyranose (TOGE), a glycoside derivative of adipic acid monoethyl ester and 1,2,3,4-tetra-O-acetyl-beta- D-glucopyranose, was synthesized and the resistance-inducing activity shown by TOGE-1 (TOGE plus furfurylamine) and TOGE-2 (TOGE plus 1,3-diaminepropane) was assayed. TOGE-1 and TOGE-2 protected tomato plants against two different fungal pathogens Phytophthora citrophthora and Alternaria solani. Foliar treatments at very low concentrations (2.5 mg l(-1) TOGE, 0.5 mg l(-1) amine) clearly reduced the disease incidence for both pathogens. TOGE-2 application was the most effective on intact plants as well as on detached leaves, reducing fungal growth by more than 46% with respect to control plants. On the other hand TOGE-1 treatment reduced fungal advance by 21%. These results demonstrate a high protective effect against fungal infections for both chemicals. A possible direct antimicrobial effect was discounted due to the weak activity observed in vitro against these pathogens at the low concentrations used in plants. TOGE-2 treatment clearly activates resistance against both pathogens and improves the protective effect previously shown by FGA mixture (adipic acid monoethyl ester, 1,2,3,4-tetra-O-acetyl-beta- D-glucopyranose and furfurylamine) [V. Flors et al. (2001) J Agric Food Chem 49:2569-2575]. The obtained results indicate that TOGE-1 and TOGE-2 act as resistance inducers. Although their mode of action is still unknown, pre-challenge studies have demonstrated the induction of the phenylpropanoid pathway and antioxidant activities. Both chemicals have demonstrated a beneficial effect on plant development, increasing chlorophyll and protein contents, photosynthetic rate and water-use efficiency. The improvement of plant growth and development produced by these treatments suggests crop tolerance to these chemicals, although effective formulations that are safe to humans must be developed before this technology can

  15. Development and validation of a fast PCR-based detection method for pathogenic isolates of the citrus black spot fungus, Guignardia citricarpa

    NARCIS (Netherlands)

    Bonants, P.J.M.; Carroll, G.C.; Weerdt, de M.; Brouwershaven, van I.R.; Baayen, R.P.

    2003-01-01

    Based on the ITS regions of the ribosomal DNA, specific primer sets were developed for the citrus pathogen Guignardia citricarpa and the common citrus endophyte, G. mangiferae, and tested for their specificity against 37 isolates of G. citricarpa, 29 isolates of G. mangiferae, 10 isolates of related

  16. Sequence diversity on four ORFs of citrus tristeza virus correlates with pathogenicity

    Directory of Open Access Journals (Sweden)

    Martínez-Soriano Juan

    2009-07-01

    Full Text Available Abstract The molecular characterization of isolates of citrus tristeza virus (CTV from eight locations in Mexico was undertaken by analyzing five regions located at the opposite ends of the virus genome. Two regions have been previously used to study CTV variability (coat protein and p23, while the other three correspond to other genomic segments (p349-B, p349-C and p13. Our comparative nucleotide analyses included CTV sequences from different geographical origins already deposited in the GenBank databases. The largest nucleotide differences were located in two fragments located at the 5' end of the genome (p349-B and p349-C. Phylogenetic analyses on those five regions showed that the degree of nucleotide divergence among strains tended to correlate with their pathogenicity. Two main groups were defined: mild, with almost no noticeable effects on the indicator plants and severe, with drastic symptoms. Mild isolates clustered together in every analyzed ORF sharing a genetic distance below 0.022, in contrast with the severe isolates, which showed a more disperse distribution and a genetic distance of 0.276. Analyses of the p349-B and p349-C regions evidenced two lineages within the severe group: severe common subgroup (most of severe isolates and severe divergent subgroup (T36-like isolates. This study represents the first attempt to analyze the genetic variability of CTV in Mexico by constructing phylogenetic trees based on new genomic regions that use group-specific nucleotide and amino acid sequences. These results may be useful to implement specific assays for strain discrimination. Moreover, it would be an excellent reference for the CTV situation in México to face the recent arrival of brown citrus aphid.

  17. Inhibitory effects of Fortunella japonica var. margarita and Citrus sunki essential oils on nitric oxide production and skin pathogens.

    Science.gov (United States)

    Yang, Eun-Jin; Kim, Sang Suk; Moon, Ji-Young; Oh, Tae-Heon; Baik, Jong Seok; Lee, Nam Ho; Hyun, Chang-Gu

    2010-03-01

    A number of essential oils from citrus peels are claimed to have biological activities. Citrus peel, called 'Jin-Pi', is used in traditional medicine for digestion, severe cold, and fever. However, the antibacterial activities against skin pathogens and anti-inflammatory effects of the essential oils of Citrus sunki (JinGyul) and Fortunella japonica var. margarita (GumGyul) have not yet been described. Therefore, in this study, the essential oils of the citrus species C. sunki (CSE) and F. japonica var. margarita (FJE), both native to the island of Jeju, Korea, were examined for their anti-inflammatory and antimicrobial activities against skin pathogens. Four human skin pathogenic microorganisms, Staphylococcus epidermidis CCARM 3709, Propionibacterium acnes CCARM 0081, Malassezia furfur KCCM 12679, and Candida albicans KCCM 11282, were studied. CSE and FJE exhibited strong antimicrobial activity against most of the pathogenic bacteria and yeast strains that were tested. Interestingly, CSE and FJE even showed antimicrobial activity against antibiotic-resistant S. epidermidis CCARM 3710, S. epidermidis CCARM 3711, P. acnes CCARM9009, and P. acnes CCARM9010 strains. In addition, CSE and FJE reduced the lipopolysaccharide (LPS)-induced secretion of nitric oxide (NO) in RAW 264.7 cells, indicating that they have anti-inflammatory effects. We also analysed the chemical composition of the oils by gas chromatography-mass spectrometry (GC-MS) and identified several major components, including dl-limonene (68.18%) and beta-myrcene (4.36%) for CSE, and dl-limonene (61.58%) and carvone (6.36%) for FJE. Taken together, these findings indicate that CSE and FJE have great potential to be used in human skin health applications.

  18. Occurrence, molecular characterisation, and pathogenicity of Neoscytalidium dimidiatum on Citrus in Italy

    NARCIS (Netherlands)

    Polizzi, G.; Aiello, D.; Castello, I.; Vitale, A.; Groenewald, J.Z.; Crous, P.W.; Gentile, A.; La Malfa, S.

    2011-01-01

    During 2008 and 2009, a new disease was noticed in eastern Sicily (Italy) in two re-grafted citrus orchards (Citrus sinensis (L.) Osbeck) on sour orange rootstock. Symptoms consisted of blight of vigorously growing shoots and a sooty canker on shoots and rootstock trunks. A Scytalidium-like fungus w

  19. Occurrence, molecular characterisation, and pathogenicity of Neoscytalidium dimidiatum on citrus in Italy

    NARCIS (Netherlands)

    Polizzi, G.; Aiello, D.; Castello, I.; Vitale, A.; Groenewald, J.Z.; Crous, P.W.

    2011-01-01

    During 2008 and 2009, a new disease was noticed in eastern Sicily (Italy) in two re-grafted citrus orchards (Citrus sinensis (L.) Osbeck) on sour orange rootstock. Symptoms consisted of blight of vigorously growing shoots and a sooty canker on shoots and rootstock trunks. A Scytalidium-like fungus w

  20. Alternaria in aardappel

    NARCIS (Netherlands)

    Spits, H.G.

    2005-01-01

    De laatste jaren komt een aantasting door Alternaria in aardappel steeds vaker voor. Door een aantasting sterft het gewas vervroegd af. Dit heeft opbrengstderving tot gevolg. Ook kunnen de geoogste knollen aangetast worden. De oorzaak, dat Alternaria de laatste jaren vaker voorkomt dan voorheen is,

  1. Expression of ß-1,3-glucanase and ß-1,4-glucanase in two potato cultivars following challenge by the fungal pathogen Alternaria solani

    Science.gov (United States)

    Early blight of potato, caused by Alternaria solani, is a ubiquitous disease in many countries around the world. We have previously found that variation in resistance phenotypes exist between two different Iranian cultivars of potato. Cultivar ‘Diamond’ is more resistant to multiple isolates of A. s...

  2. Identification of putative TAL effector targets of the citrus canker pathogens shows functional convergence underlying disease development and defense response.

    Science.gov (United States)

    Pereira, Andre L A; Carazzolle, Marcelo F; Abe, Valeria Y; de Oliveira, Maria L P; Domingues, Mariane N; Silva, Jaqueline C; Cernadas, Raul A; Benedetti, Celso E

    2014-02-25

    Transcriptional activator-like (TAL) effectors, formerly known as the AvrBs3/PthA protein family, are DNA-binding effectors broadly found in Xanthomonas spp. that transactivate host genes upon injection via the bacterial type three-secretion system. Biologically relevant targets of TAL effectors, i.e. host genes whose induction is vital to establish a compatible interaction, have been reported for xanthomonads that colonize rice and pepper; however, citrus genes modulated by the TAL effectors PthA"s" and PthC"s" of the citrus canker bacteria Xanthomonas citri (Xc) and Xanthomonas aurantifolii pathotype C (XaC), respectively, are poorly characterized. Of particular interest, XaC causes canker disease in its host lemon (Citrus aurantifolia), but triggers a defense response in sweet orange. Based on, 1) the TAL effector-DNA binding code, 2) gene expression data of Xc and XaC-infiltrated sweet orange leaves, and 3) citrus hypocotyls transformed with PthA2, PthA4 or PthC1, we have identified a collection of Citrus sinensis genes potentially targeted by Xc and XaC TAL effectors. Our results suggest that similar with other strains of Xanthomonas TAL effectors, PthA2 and PthA4, and PthC1 to some extent, functionally converge. In particular, towards induction of genes involved in the auxin and gibberellin synthesis and response, cell division, and defense response. We also present evidence indicating that the TAL effectors act as transcriptional repressors and that the best scoring predicted DNA targets of PthA"s" and PthC"s" in citrus promoters predominantly overlap with or localize near to TATA boxes of core promoters, supporting the idea that TAL effectors interact with the host basal transcriptional machinery to recruit the RNA pol II and start transcription. The identification of PthA"s" and PthC"s" targets, such as the LOB (lateral organ boundary) and CCNBS genes that we report here, is key for the understanding of the canker symptoms development during host

  3. Prophage-Mediated Dynamics of ‘Candidatus Liberibacter asiaticus’ Populations, the Destructive Bacterial Pathogens of Citrus Huanglongbing

    Science.gov (United States)

    Zhou, Lijuan; Powell, Charles A.; Li, Wenbin; Irey, Mike; Duan, Yongping

    2013-01-01

    Prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. There are at least two prophages in the chromosomes of Candidatus Liberibacter asiaticus’ (Las) Floridian isolates. Las is both unculturable and the most prevalent species of Liberibacter pathogens that cause huanglongbing (HLB), a worldwide destructive disease of citrus. In this study, seven new prophage variants resulting from two hyper-variable regions were identified by screening clone libraries of infected citrus, periwinkle and psyllids. Among them, Types A and B share highly conserved sequences and localize within the two prophages, FP1 and FP2, respectively. Although Types B and C were abundant in all three libraries, Type A was much more abundant in the libraries from the Las-infected psyllids than from the Las-infected plants, and Type D was only identified in libraries from the infected host plants but not from the infected psyllids. Sequence analysis of these variants revealed that the variations may result from recombination and rearrangement events. Conventional PCR results using type-specific molecular markers indicated that A, B, C and D are the four most abundant types in Las-infected citrus and periwinkle. However, only three types, A, B and C are abundant in Las-infected psyllids. Typing results for Las-infected citrus field samples indicated that mixed populations of Las bacteria present in Floridian isolates, but only the Type D population was correlated with the blotchy mottle symptom. Extended cloning and sequencing of the Type D region revealed a third prophage/phage in the Las genome, which may derive from the recombination of FP1 and FP2. Dramatic variations in these prophage regions were also found among the global Las isolates. These results are the first to demonstrate the prophage/phage-mediated dynamics of Las populations in plant and insect hosts, and their correlation with insect transmission and disease

  4. Protein interaction networks at the host–microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen

    Science.gov (United States)

    Chavez, J. D.; Johnson, R.; Hosseinzadeh, S.; Mahoney, J. E.; Mohr, J. P.; Robison, F.; Zhong, X.; Hall, D. G.; MacCoss, M.; Bruce, J.; Cilia, M.

    2017-01-01

    The Asian citrus psyllid (Diaphorina citri) is the insect vector responsible for the worldwide spread of ‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host–microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host–microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening. PMID:28386418

  5. Fungicidal activity of silver nanoparticles against Alternaria brassicicola

    Science.gov (United States)

    Gupta, Deepika; Chauhan, Pratima

    2016-04-01

    This work highlighted the fungicidal properties of silver nanoparticles against Alternaria brassicicola. Alternaria brassicicola causes Black spot of Cauliflower, radish, cabbage, kale which results in sever agricultural loss. We treat the synthesised silver nanoparticles (AgNPs) of 10, 25, 50, 100 and 110 ppm concentrations against Alternaria brassicicola on PDA containing Petri dish. We calculated inhibitory rate (%) in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. Treatment with 100ppm AgNPs resulted in maximum inhibition of Alternaria brassicicola i.e.92.2%. 110ppm of AgNPS also shows the same result, therefore 100ppm AgNPs was treated as optimize concentration. AgNPs effectively inhibited the growth of a Alternaria brassicicola, which suggests that AgNPs could be used as fungicide in plant disease management. Further research and development are necessary to translate this technology into plant disease management strategies.

  6. Influence of volatile constituents of fruit peels of Citrus reticulata Blanco on clinically isolated pathogenic microorganisms under In-vitro

    Institute of Scientific and Technical Information of China (English)

    Husain Shahnaz Sultana; Mohammed Ali; Bibhu Prasad Panda

    2012-01-01

    Objective: To investigate the antimicrobial activity of volatile constituents of fruit peels of Citrus reticulata Blanco on clinically isolated pathogenic microorganisms. Methods: Extraction of volatile oil was carried out by Clevenger’s apparatus. Volatile chemical components were measured by GC-MS. Antimicrobial activity was carried by Agar well diffusion assay with reference to standard fluconazole and tetracycline. Results: The chemical composition of volatile oil of the fruit peels of Citrus reticulata Blanco (Rutaceae) of Delhi Region was composed mainly monoterpenes (99.1 %) constituting l-limonene (92.4 %), γ-terpene (2.6 %) andβ-phellandrene (1.8 %). The volatile oil showed antibacterial and antifungal activities against the clinically isolated pathogenic microbial strains Escherichia coli, Staphylococcus aureus, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus and Candida albicans under in vitro condition. Conclusions: The potential antimicrobial activity of volatile oil present in fruit peels of C. reticulata can be useful for treatment of skin disorder and/or in aroma. Therapy, it can be incorporated into cosmetic formulations.

  7. Bacterial diversity analysis of Huanglongbing pathogen-infected citrus, using PhyloChip and 16S rRNA gene clone library sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Shankar Sagaram, U.; DeAngelis, K.M.; Trivedi, P.; Andersen, G.L.; Lu, S.-E.; Wang, N.

    2009-03-01

    The bacterial diversity associated with citrus leaf midribs was characterized 1 from citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rDNA microarray and 16S rDNA clone library sequencing to determine the microbial community composition of symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria from 15 phyla were present in the citrus leaf midribs while 20 orders from phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs compared to asymptomatic midribs. Candidatus Liberibacter asiaticus (Las) was detected at a very low level in asymptomatic plants, but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis was further verified by sequencing 16S rDNA clone libraries, which indicated the dominance of Las in symptomatic leaves. These data implicate Las as the pathogen responsible for HLB disease. Citrus is the most important commercial fruit crop in Florida. In recent years, citrus Huanglongbing (HLB), also called citrus greening, has severely affected Florida's citrus production and hence has drawn an enormous amount of attention. HLB is one of the most devastating diseases of citrus (6,13), characterized by blotchy mottling with green islands on leaves, as well as stunting, fruit decline, and small, lopsided fruits with poor coloration. The disease tends to be associated with a phloem-limited fastidious {alpha}-proteobacterium given a provisional Candidatus status (Candidatus Liberobacter spp. later changed to Candidatus Liberibacter spp.) in nomenclature (18,25,34). Previous studies indicate that HLB infection causes disorder in the phloem and severely impairs the translocation of assimilates in

  8. Bacterial diversity analysis of Huanglongbing pathogen-infected citrus, using PhyloChip and 16S rRNA gene clone library sequencing

    Energy Technology Data Exchange (ETDEWEB)

    Shankar Sagaram, U.; DeAngelis, K.M.; Trivedi, P.; Andersen, G.L.; Lu, S.-E.; Wang, N.

    2009-03-01

    The bacterial diversity associated with citrus leaf midribs was characterized 1 from citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rDNA microarray and 16S rDNA clone library sequencing to determine the microbial community composition of symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria from 15 phyla were present in the citrus leaf midribs while 20 orders from phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs compared to asymptomatic midribs. Candidatus Liberibacter asiaticus (Las) was detected at a very low level in asymptomatic plants, but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis was further verified by sequencing 16S rDNA clone libraries, which indicated the dominance of Las in symptomatic leaves. These data implicate Las as the pathogen responsible for HLB disease. Citrus is the most important commercial fruit crop in Florida. In recent years, citrus Huanglongbing (HLB), also called citrus greening, has severely affected Florida's citrus production and hence has drawn an enormous amount of attention. HLB is one of the most devastating diseases of citrus (6,13), characterized by blotchy mottling with green islands on leaves, as well as stunting, fruit decline, and small, lopsided fruits with poor coloration. The disease tends to be associated with a phloem-limited fastidious {alpha}-proteobacterium given a provisional Candidatus status (Candidatus Liberobacter spp. later changed to Candidatus Liberibacter spp.) in nomenclature (18,25,34). Previous studies indicate that HLB infection causes disorder in the phloem and severely impairs the translocation of assimilates in

  9. Alternaria in Food: Ecophysiology, Mycotoxin Production and Toxicology.

    Science.gov (United States)

    Lee, Hyang Burm; Patriarca, Andrea; Magan, Naresh

    2015-06-01

    Alternaria species are common saprophytes or pathogens of a wide range of plants pre- and post-harvest. This review considers the relative importance of Alternaria species, their ecology, competitiveness, production of mycotoxins and the prevalence of the predominant mycotoxins in different food products. The available toxicity data on these toxins and the potential future impacts of Alternaria species and their toxicity in food products pre- and post-harvest are discussed. The growth of Alternaria species is influenced by interacting abiotic factors, especially water activity (aw), temperature and pH. The boundary conditions which allow growth and toxin production have been identified in relation to different matrices including cereal grain, sorghum, cottonseed, tomato, and soya beans. The competitiveness of Alternaria species is related to their water stress tolerance, hydrolytic enzyme production and ability to produce mycotoxins. The relationship between A. tenuissima and other phyllosphere fungi has been examined and the relative competitiveness determined using both an Index of Dominance (ID) and the Niche Overlap Index (NOI) based on carbon-utilisation patterns. The toxicology of some of the Alternaria mycotoxins have been studied; however, some data are still lacking. The isolation of Alternaria toxins in different food products including processed products is reviewed. The future implications of Alternaria colonization/infection and the role of their mycotoxins in food production chains pre- and post-harvest are discussed.

  10. Comparison of PCR,DIA and Pathogenicity Assay for Detection of Xanthomonas axonopodis pv.citri,the Causal Agent of Citrus Bacterial Canker Disease

    Institute of Scientific and Technical Information of China (English)

    WANG Zhong-kang; SUN Xian-yun; YIN You-ping; ZHOU Chang-yong; XIA Yu-xian

    2004-01-01

    Polymerase chain reaction (PCR) approach based on newly designed primers, JYF5/JYR5, was applied for specific detection of Xanthomonas axonopodis pv.citri(Xac). The efficiency and reliability of PCR method were compared with dot immunobinding assay (DIA) and classical pathogenicity test techniques for detecting suspensions of pure cells of Xac and soaking sap of citrus tissues. Detection sensitivity of PCR was about 4.5 cells or 1.56 pg target DNA per reaction which was higher than that of DIA (ca. 450 cells per dot).These three techniques (PCR assay, DIA and Pathogenecity test) could always detect Xac from symptomatic citrus samples. Different performances were obtained from citrus materials without symptoms, and the positive detection frequency was PCR, DIA and pathogenicity test.

  11. Symptomatic Citrus trees reveal a new pathogenic lineage in Fusarium and two new Neocosmospora species

    NARCIS (Netherlands)

    Sandoval-Denis, M.; Guarnaccia, V.; Polizzi, G.; Crous, P.W.

    2018-01-01

    The diversity of fusaria in symptomatic Citrus trees in Greece, Italy and Spain was evaluated using morphological and molecular multi-locus analyses based on fragments of the calmodulin (CAM), intergenic spacer region of the rDNA (IGS), internal transcribed spacer region of the rDNA (ITS), large

  12. Beheersing van Alternaria in aardappel

    NARCIS (Netherlands)

    Spits, H.G.

    2007-01-01

    De laatste jaren komt Alternaria in aardappel meer voor. In 2004 waren er vooral problemen in het Zuidwesten van Nederland. Ook werden hier verschillende partijen waargenomen met knolaantasting. Voor 2004 was knolaantasting door Alternaria in Nederland uiterst zeldzaam. Omdat Alternaria zelden probl

  13. Effect of X-irradiation on Citrus Canker Pathogen Xanthomonas citri subsp. citri of Satsuma Mandarin Fruits

    Directory of Open Access Journals (Sweden)

    Min-A Song

    2015-12-01

    Full Text Available Citrus canker caused by Xanthomonas citri subsp. citri (Xcc is one of the most important bacterial diseases of citrus. Because citrus canker is not found in many countries including European Union and Australia, Xcc is strictly regulated in order to prevent its spread. In this study, the effects of X-irradiation on Xcc growth either in the suspension or on the surface of citrus fruits were investigated. The suspension containing 1×10⁷ cfu/ml of Xcc was irradiated with different absorbed doses of X-irradiation ranging from 50 to 400 Gy. The results showed that Xcc was fully dead at 400 Gy of X-irradiation. To determine the effect of X-irradiation on quarantine, the Xcc-inoculated citrus fruits were irradiated with different X-ray doses at which Xcc was completely inhibited by an irradiation dose of 250 Gy. The D₁₀ value for Xcc on citrus fruits was found to be 97 Gy, indicating the possibility of direct application on citrus quarantine without any side sterilizer. Beside, presence of Xcc on the surface of asymptomatic citrus fruits obtained from citrus canker-infected orchards was noted. It indicated that the exporting citrus fruits need any treatment so that Xcc on the citrus fruits should be completely eliminated. Based on these results, ionizing radiation can be considered as an alternative method of eradicating Xcc for export of citrus fruits.

  14. Improved annotation of the insect vector of citrus greening disease: Biocuration by a diverse genomics community

    Science.gov (United States)

    The Asian citrus psyllid (Diaphorina citri Kuwayama) is the insect vector of the bacterium Candidatus Liberibacter asiaticus (CLas), the pathogen associated with citrus Huanglongbing (HLB, citrus greening). HLB threatens citrus production worldwide. Suppression or reduction of the insect vector usin...

  15. Annotation of the Asian citrus psyllid genome reveals a reduced innate immune system

    Science.gov (United States)

    Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuway...

  16. Pathogenic Interactions Between Xanthomonas axonopodis pv. citri and Cultivars of Pummelo (Citrus grandis).

    Science.gov (United States)

    Shiotani, H; Ozaki, K; Tsuyumu, S

    2000-12-01

    ABSTRACT The aggressiveness of strains of Xanthomonas axonopodis pv. citri on seven Citrus species, including Citrus sinensis (navel orange), C. paradisi (grapefruit), C. unshiu (Satsuma mandarin), C. junos (Yuzu), C. aurantifolia ('Mexican' lime), C. tachibana (Tachibana), and C. grandis (pummelo: 'Otachibana', 'Banpeiyu', and 'Anseikan'), were assessed by comparing lesion expansion and growth in planta, using a prick inoculation method. The existence of two groups distinct in aggressiveness was demonstrated on the pummelo cultivars, whereas the remaining species tested were uniformly susceptible. The two groups of strains were distinct in lesion expansion and growth in planta; however, both caused canker lesions on the 'Otachibana' pummelo. The sensitivity of the bacterial strains to phages Cp1 and Cp2 was associated with differences in aggressiveness. Namely, all the strains sensitive to Cp2 but resistant to Cp1 were aggressive to 'Otachibana', whereas all the strains sensitive to Cp1 but resistant to Cp2 were weakly aggressive. When a repetitive sequence-based polymerase chain reaction amplification was carried out by enterobacterial repetitive intergeneric consensus (ERIC) sequences (ERIC1R and ERIC2) as the primers, these two groups were also distinguishable by the presence or absence of a 1.8-kb DNA fragment among otherwise identical fragments. The 1.8-kb fragment was amplified only from the strains aggressive to C. grandis.

  17. Genomic and transcriptomic analyses of the tangerine pathotype of Alternaria alternata in response to oxidative stress

    Science.gov (United States)

    Wang, Mingshuang; Sun, Xuepeng; Yu, Dongliang; Xu, Jianping; Chung, Kuangren; Li, Hongye

    2016-01-01

    The tangerine pathotype of Alternaria alternata produces the A. citri toxin (ACT) and is the causal agent of citrus brown spot that results in significant yield losses worldwide. Both the production of ACT and the ability to detoxify reactive oxygen species (ROS) are required for A. alternata pathogenicity in citrus. In this study, we report the 34.41 Mb genome sequence of strain Z7 of the tangerine pathotype of A. alternata. The host selective ACT gene cluster in strain Z7 was identified, which included 25 genes with 19 of them not reported previously. Of these, 10 genes were present only in the tangerine pathotype, representing the most likely candidate genes for this pathotype specialization. A transcriptome analysis of the global effects of H2O2 on gene expression revealed 1108 up-regulated and 498 down-regulated genes. Expressions of those genes encoding catalase, peroxiredoxin, thioredoxin and glutathione were highly induced. Genes encoding several protein families including kinases, transcription factors, transporters, cytochrome P450, ubiquitin and heat shock proteins were found associated with adaptation to oxidative stress. Our data not only revealed the molecular basis of ACT biosynthesis but also provided new insights into the potential pathways that the phytopathogen A. alternata copes with oxidative stress. PMID:27582273

  18. Tomato resistance to Alternaria stem canker : localization in host genotypes and functional expression compared to non-host resistance

    NARCIS (Netherlands)

    Witsenboer, H.M.A.; Griend, E.G. van de; Tiersma, J.B.; Nijkamp, H.J.J.; Hille, J.

    1989-01-01

    The Alternaria stem canker resistance locus (Asc-locus), involved in resistance to the fungal pathogen Alternaria alternata f. sp. lycopersici and in insensitivity to host-specific toxins (AAL-toxins) produced by the pathogen, was genetically mapped on the tomato genome. Susceptibility and resistanc

  19. Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea

    Directory of Open Access Journals (Sweden)

    Jian Xin Deng

    2015-03-01

    Full Text Available In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

  20. Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea.

    Science.gov (United States)

    Deng, Jian Xin; Lee, Ji Hye; Paul, Narayan Chandra; Cho, Hye Sun; Lee, Hyang Burm; Yu, Seung Hun

    2015-03-01

    In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus) leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

  1. Structural and Physiological Analyses of the Alkanesulphonate-Binding Protein (SsuA) of the Citrus Pathogen Xanthomonas citri

    Science.gov (United States)

    Tófoli de Araújo, Fabiano; Bolanos-Garcia, Victor M.; Pereira, Cristiane T.; Sanches, Mario; Oshiro, Elisa E.; Ferreira, Rita C. C.; Chigardze, Dimitri Y.; Barbosa, João Alexandre Gonçalves; de Souza Ferreira, Luís Carlos; Benedetti, Celso E.; Blundell, Tom L.; Balan, Andrea

    2013-01-01

    Background The uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. Until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the Xanthomonas genus, which encompasses several pathogenic species. In the present study, we characterised the alkanesulphonate uptake system (Ssu) of Xanthomonas axonopodis pv. citri 306 strain (X. citri), the etiological agent of citrus canker. Methodology/Principal Findings A single operon-like gene cluster (ssuEDACB) that encodes both the sulphur uptake system and enzymes involved in desulphurisation was detected in the genomes of X. citri and of the closely related species. We characterised X. citri SsuA protein, a periplasmic alkanesulphonate-binding protein that, together with SsuC and SsuB, defines the alkanesulphonate uptake system. The crystal structure of SsuA bound to MOPS, MES and HEPES, which is herein described for the first time, provides evidence for the importance of a conserved dipole in sulphate group coordination, identifies specific amino acids interacting with the sulphate group and shows the presence of a rather large binding pocket that explains the rather wide range of molecules recognised by the protein. Isolation of an isogenic ssuA-knockout derivative of the X. citri 306 strain showed that disruption of alkanesulphonate uptake affects both xanthan gum production and generation of canker lesions in sweet orange leaves. Conclusions/Significance The present study unravels unique structural and functional features of the X. citri SsuA protein and provides the first experimental evidence that an ABC uptake system affects the virulence of this phytopathogen. PMID:24282519

  2. Structural and physiological analyses of the alkanesulphonate-binding protein (SsuA of the citrus pathogen Xanthomonas citri.

    Directory of Open Access Journals (Sweden)

    Fabiano Tófoli de Araújo

    Full Text Available BACKGROUND: The uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. Until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the Xanthomonas genus, which encompasses several pathogenic species. In the present study, we characterised the alkanesulphonate uptake system (Ssu of Xanthomonas axonopodis pv. citri 306 strain (X. citri, the etiological agent of citrus canker. METHODOLOGY/PRINCIPAL FINDINGS: A single operon-like gene cluster (ssuEDACB that encodes both the sulphur uptake system and enzymes involved in desulphurisation was detected in the genomes of X. citri and of the closely related species. We characterised X. citri SsuA protein, a periplasmic alkanesulphonate-binding protein that, together with SsuC and SsuB, defines the alkanesulphonate uptake system. The crystal structure of SsuA bound to MOPS, MES and HEPES, which is herein described for the first time, provides evidence for the importance of a conserved dipole in sulphate group coordination, identifies specific amino acids interacting with the sulphate group and shows the presence of a rather large binding pocket that explains the rather wide range of molecules recognised by the protein. Isolation of an isogenic ssuA-knockout derivative of the X. citri 306 strain showed that disruption of alkanesulphonate uptake affects both xanthan gum production and generation of canker lesions in sweet orange leaves. CONCLUSIONS/SIGNIFICANCE: The present study unravels unique structural and functional features of the X. citri SsuA protein and provides the first experimental evidence that an ABC uptake system affects the virulence of this phytopathogen.

  3. Genome sequence of the necrotrophic fungus Penicillium digitatum, the main postharvest pathogen of citrus

    Directory of Open Access Journals (Sweden)

    Marcet-Houben Marina

    2012-11-01

    Full Text Available Abstract Background Penicillium digitatum is a fungal necrotroph causing a common citrus postharvest disease known as green mold. In order to gain insight into the genetic bases of its virulence mechanisms and its high degree of host-specificity, the genomes of two P. digitatum strains that differ in their antifungal resistance traits have been sequenced and compared with those of 28 other Pezizomycotina. Results The two sequenced genomes are highly similar, but important differences between them include the presence of a unique gene cluster in the resistant strain, and mutations previously shown to confer fungicide resistance. The two strains, which were isolated in Spain, and another isolated in China have identical mitochondrial genome sequences suggesting a recent worldwide expansion of the species. Comparison with the closely-related but non-phytopathogenic P. chrysogenum reveals a much smaller gene content in P. digitatum, consistent with a more specialized lifestyle. We show that large regions of the P. chrysogenum genome, including entire supercontigs, are absent from P. digitatum, and that this is the result of large gene family expansions rather than acquisition through horizontal gene transfer. Our analysis of the P. digitatum genome is indicative of heterothallic sexual reproduction and reveals the molecular basis for the inability of this species to assimilate nitrate or produce the metabolites patulin and penicillin. Finally, we identify the predicted secretome, which provides a first approximation to the protein repertoire used during invasive growth. Conclusions The complete genome of P. digitatum, the first of a phytopathogenic Penicillium species, is a valuable tool for understanding the virulence mechanisms and host-specificity of this economically important pest.

  4. Genome sequence of the necrotrophic fungus Penicillium digitatum, the main postharvest pathogen of citrus.

    Science.gov (United States)

    Marcet-Houben, Marina; Ballester, Ana-Rosa; de la Fuente, Beatriz; Harries, Eleonora; Marcos, Jose F; González-Candelas, Luis; Gabaldón, Toni

    2012-11-21

    Penicillium digitatum is a fungal necrotroph causing a common citrus postharvest disease known as green mold. In order to gain insight into the genetic bases of its virulence mechanisms and its high degree of host-specificity, the genomes of two P. digitatum strains that differ in their antifungal resistance traits have been sequenced and compared with those of 28 other Pezizomycotina. The two sequenced genomes are highly similar, but important differences between them include the presence of a unique gene cluster in the resistant strain, and mutations previously shown to confer fungicide resistance. The two strains, which were isolated in Spain, and another isolated in China have identical mitochondrial genome sequences suggesting a recent worldwide expansion of the species. Comparison with the closely-related but non-phytopathogenic P. chrysogenum reveals a much smaller gene content in P. digitatum, consistent with a more specialized lifestyle. We show that large regions of the P. chrysogenum genome, including entire supercontigs, are absent from P. digitatum, and that this is the result of large gene family expansions rather than acquisition through horizontal gene transfer. Our analysis of the P. digitatum genome is indicative of heterothallic sexual reproduction and reveals the molecular basis for the inability of this species to assimilate nitrate or produce the metabolites patulin and penicillin. Finally, we identify the predicted secretome, which provides a first approximation to the protein repertoire used during invasive growth. The complete genome of P. digitatum, the first of a phytopathogenic Penicillium species, is a valuable tool for understanding the virulence mechanisms and host-specificity of this economically important pest.

  5. The potential for citrus cryotherapy

    Science.gov (United States)

    Citrus collections of pathogen-free plants are needed for breeding, research, and distribution to the user community. The Citrus Research Board funded research project “Development of cryotherapy as an improved method of eliminating graft transmissible pathogens in Citrus” sought to use cryotherapy,...

  6. 柑橘褐斑病室内快速评价方法的研究%A rapid laboratory evaluation method of citrus brown spot caused by Alternaria alternate

    Institute of Scientific and Technical Information of China (English)

    刘荣萍; 胡军华; 姚廷山; 王雪莲; 左佩佩; 王延杰; 李鸿筠

    2013-01-01

    [目的]柑橘褐斑病是我国柑橘上一种严重危害嫩叶、嫩梢及果实的病害,研究拟建快速、可靠、稳定及操作简便的柑橘褐斑病菌室内评价方法.[方法]在‘温州蜜柑’离体叶片和果实上造成不同伤口,用强致病菌hjx接种,[结果]25℃保湿培养后调查发现不接菌对照有、无伤口不发病;各种伤口接种病原菌均能发病,但伤口类型对病害影响很大.叶片反面较叶片正面更易于发病,叶片反面10针、1针及无伤接种发病无明显差异;果实表面针刺1针、10针及去除果皮接种对发病影响很大,差异极显著.进一步用6个不同柑橘品种及Alternaria citri ZYF,Alternaria sp.MP3 2个菌株验证方法的可靠性和稳定性,发现菌株hjx在不同品种上致病力存在差异,2个菌株之间的致病力存在差异.[结论]以离体柑橘叶片或果实为材料,叶片反面1针接种或果实去皮接种,25℃保湿培养2d后调查病斑大小,可作为室内准确、快速评价柑橘褐斑病致病力的方法.该方法可用于筛选抗病材料,评价分离菌株的致病性和药剂的防病效果等.

  7. Secondary metabolite profiling of Alternaria dauci, A. porri, A. solani, and A. tomatophila

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Dongo, Anita; Pryor, Barry M.

    2008-01-01

    Chemotaxonomy (secondary metabolite profiling) has been shown to be of great value in the classification and differentiation in Ascomycota. However, few studies have investigated the use of metabolite production for classification and identification purposes of plant pathogenic Alternaria species...

  8. Ecobiophysical Aspects on Nanosilver Biogenerated from Citrus reticulata Peels, as Potential Biopesticide for Controlling Pathogens and Wetland Plants in Aquatic Media

    Directory of Open Access Journals (Sweden)

    Marcela Elisabeta Barbinta-Patrascu

    2017-01-01

    Full Text Available In recent years, a considerable interest was paid to ecological strategies in management of plant diseases and plant growth. Metallic nanoparticles (MNPs gained considerable interest as alternative to pesticides due to their interesting properties. Green synthesis of MNPs using plant extracts is very advantageous taking into account the fact that plants are easily available and eco-friendly and possess many phytocompounds that help in bioreduction of metal ions. In this research work, we phytosynthesized AgNPs from aqueous extract of Citrus reticulata peels, with high antioxidant, antibacterial, and antifungal potential. These “green” AgNPs were characterized by modern biophysical methods (absorption and FTIR spectroscopy, AFM, and zeta potential measurements. The nanobioimpact of Citrus-based AgNPs on four invasive wetland plants, Cattail (Typha latifolia, Flowering-rush (Butomus umbellatus, Duckweed (Lemna minor, and Water-pepper (Polygonum hydropiper, was studied by absorption spectroscopy, by monitoring the spectral signature of chlorophyll. The invasive plants exhibited different behavior under AgNP stress. Deep insights were obtained from experiments conducted on biomimetic membranes marked with chlorophyll a. Our results pointed out the potential use of Citrus-based AgNPs as alternative in controlling pathogens in aqueous media and in management of aquatic weeds growth.

  9. Pathogens of citrus sooty moulds%柑橘煤污病病原菌的研究

    Institute of Scientific and Technical Information of China (English)

    周小燕; 张斌; 耿坤; 姜于兰

    2013-01-01

    采用病菌标本直接观察和人工培养物观察两种方法对贵州柑橘煤污病病原菌进行了鉴定.结果表明,柑橘煤污病的优势病原菌为Chaetothyrium spinigerum、Triposporiopsis spinigera、Fumago vagans、Cladosporium cladosporioides、Alternaria tenuissima和A.alternate 6种.

  10. Citrus quarantine, sanitary and certification programs in the USA. Prevention of introduction and distribution of citrus diseases

    Science.gov (United States)

    Citrus germplasm originated in Australasia, the Far East, and Africa, thus all citrus grown in the New World was imported. This importation of citrus also resulted in importation of graft transmissible pathogens of citrus, many of which are latent in their original host but can cause epidemics of t...

  11. Survey for Citrus diseases in French Guiana

    OpenAIRE

    Thermoz, Jean-Pierre

    2007-01-01

    The presence on the continent of major threats for Citrus orchards has required a survey to assess the situation of Citrus pathogens in the French territory of Guiana. Agriculture in French Guiana is located on the coast (about 300 Kms from west to east and 50 Km wide). There are 1200 Ha of Citrus orchards (Ministry of Agriculture). Citrus are grown either for export (Tahiti lime) or for local consumption : sweet oranges, tangerines and hybrids. Trees are grafted on Carrizo citrange, Rough le...

  12. Characterization of small-spored Alternaria from Argentinean crops through a polyphasic approach

    DEFF Research Database (Denmark)

    da Cruz Cabral, Lucía; Rodriguero, Marcela; Stenglein, Sebastián

    2017-01-01

    exporter of agricultural products, so it is essential to thoroughly understand the physiological behaviour of this pathogen in a food safety context. Thus, the objective of this work was to characterize small-spored Alternaria spp. obtained from tomato fruits, pepper fruits, wheat grains and blueberries...... at species level through classical morphology or modern molecular techniques does not seem to be a useful tool to predict toxicological risk in food matrices. The detection of any small-spored Alternaria from Section Alternaria (D.P. Lawr., Gannibal, Peever & B.M. Pryor 2013) in food implies a potential...

  13. Alternaria in aardappel: een Europees alternatief

    NARCIS (Netherlands)

    Schepers, H.T.A.M.; Evenhuis, A.

    2010-01-01

    Vroeger kwam Alternaria in Nederland op beperkte schaal voor, tegenwoordig komt Alternaria algemeen voor en kan het in sommige rassen en jaren flink schade veroorzaken. In dit artikel wordt daarom ingegaan op verschillende aspecten van Alternaria in aardappel: symptomen, factoren die aantasting beïn

  14. Combining 'omics and microscopy to visualize interactions between the Asian citrus psyllid vector and the Huanglongbing pathogen Candidatus Liberibacter asiaticus in the insect gut.

    Science.gov (United States)

    Kruse, Angela; Fattah-Hosseini, Somayeh; Saha, Surya; Johnson, Richard; Warwick, EricaRose; Sturgeon, Kasie; Mueller, Lukas; MacCoss, Michael J; Shatters, Robert G; Cilia Heck, Michelle

    2017-01-01

    Huanglongbing, or citrus greening disease, is an economically devastating bacterial disease of citrus. It is associated with infection by the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by Diaphorina citri, the Asian citrus psyllid (ACP). For insect transmission to occur, CLas must be ingested during feeding on infected phloem sap and cross the gut barrier to gain entry into the insect vector. To investigate the effects of CLas exposure at the gut-pathogen interface, we performed RNAseq and mass spectrometry-based proteomics to analyze the transcriptome and proteome, respectively, of ACP gut tissue. CLas exposure resulted in changes in pathways involving the TCA cycle, iron metabolism, insecticide resistance and the insect's immune system. We identified 83 long non-coding RNAs that are responsive to CLas, two of which appear to be specific to the ACP. Proteomics analysis also enabled us to determine that Wolbachia, a symbiont of the ACP, undergoes proteome regulation when CLas is present. Fluorescent in situ hybridization (FISH) confirmed that Wolbachia and CLas inhabit the same ACP gut cells, but do not co-localize within those cells. Wolbachia cells are prevalent throughout the gut epithelial cell cytoplasm, and Wolbachia titer is more variable in the guts of CLas exposed insects. CLas is detected on the luminal membrane, in puncta within the gut epithelial cell cytoplasm, along actin filaments in the gut visceral muscles, and rarely, in association with gut cell nuclei. Our study provides a snapshot of how the psyllid gut copes with CLas exposure and provides information on pathways and proteins for targeted disruption of CLas-vector interactions at the gut interface.

  15. A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

    Directory of Open Access Journals (Sweden)

    Ottado Jorgelina

    2010-03-01

    Full Text Available Abstract Background Plant natriuretic peptides (PNPs belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival. Results Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 α subunit, maturase K, and α- and β-tubulin. Conclusions We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence.

  16. A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

    KAUST Repository

    Garavaglia, Betiana S

    2010-03-21

    Background: Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP) uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival.Results: Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 ? subunit, maturase K, and ?- and ?-tubulin.Conclusions: We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence. 2010 Garavaglia et al; licensee BioMed Central Ltd.

  17. Postharvest decay control of citrus fruit by preharvest pyrimethanil spray.

    Science.gov (United States)

    D'Aquino, S; Angioni, A; Suming, D; Palma, A; Schirra, M

    2013-01-01

    Preharvest infections or conidia load on fruit surface by Penicillium digitatum, P. italicum, Alternaria citri and other filamentous fungi can cause important postharvest losses of citrus fruit. Reduction in pruning frequency occurred in the last decade together with un-picked yield that eventually rots on the trees have increased the risk of postharvest decay especially when environmental conditions at picking time are favourable to pathogens' development. Sanitation procedures in the packinghouses, alternate use of postharvest fungicides with different modes of action, along with fungicide application before harvest could be an effective approach to minimize postharvest decay in citrus fruit. The present study investigated the effectiveness of a preharvest treatment with pyrimethanil (PYR), a broad spectrum fungicide, recently registered in different citrus-producing countries for postharvest treatments of citrus fruit and widely used worldwide as a preharvest treatment to control various diseases in different crops. PYR (750 mg/L) was sprayed by a hand-back sprayer at run-off on 'Fremont' mandarins. The day after the treatment, half of the trees were sprayed with a 10(4) conidial suspension of P. digitatum at run-off. Fruit were harvested following 2 or 4 weeks from treatments. Sound or either wounded 2-mm-deep and 2-mm-wide or superficial wound-scratched fruit were stored at 20 degrees C and 90% RH and inspected for decay after 1, 2 or 3 weeks of storage. In fruit harvested after 2 weeks from field treatment, PYR remarkably reduced decay development during two weeks of storage in sound fruit and in wound-scratched fruit and was fairly effective even after 4 weeks from treatment, but was ineffective in fruit wounded 2 mm deep and 2 mm wide. PYR was also effective in reducing preharvest decay incited by P. digitatum, P. italicum and Botrytis cinerea, but not by other pathogens. Results show that preharvest treatment with PYR could be a feasible approach to reduce

  18. The myosin motor domain-containing chitin synthase PdChsVII is required for development, cell wall integrity and virulence in the citrus postharvest pathogen Penicillium digitatum.

    Science.gov (United States)

    Gandía, Mónica; Harries, Eleonora; Marcos, Jose F

    2014-06-01

    Chitin is an essential component of the fungal cell wall and a potential target in the development of new antifungal compounds, due to its presence in fungi and not in plants or vertebrates. Chitin synthase genes (chs) constitute a complex family in filamentous fungi and are involved in fungal development, morphogenesis, pathogenesis and virulence. In this study, additional chs genes in the citrus postharvest pathogen Penicillium digitatum have been identified. Comparative analyses included each PdChs in each one of the classes I to VII previously established, and support the grouping of these into three divisions. Disruption of the gene coding PdChsVII, which contains a short version of a myosin motor domain, has been achieved by using Agrobacterium tumefaciens-mediated transformation and revealed its role in the life cycle of the fungus. Disruption strains were viable but showed reduced growth and conidia production. Moreover, Pdchs mutants developed morphological defects as balloon-like enlarged cells and increased chitin content, indicative of an altered cell wall structure. Gene disruption also increased susceptibility to antifungal compounds such as calcofluor white (CFW), sodium dodecyl sulfate (SDS), hydroxide peroxide (H2O2) and commercial fungicides, but significantly no change was observed in the sensitivity to antifungal peptides. The PdchsVII mutants were able to infect citrus fruit and produced tissue maceration, although had reduced virulence and most importantly were greatly impaired in the production of visible mycelium and conidia on the fruit.

  19. 柑橘黄龙病的为害传播与综合防控措施%Pathogen transmission and comprehensive control measures of citrus Huanglongbing

    Institute of Scientific and Technical Information of China (English)

    林天从

    2015-01-01

    总结柑橘黄龙病的主要危害特征、传播方式和发病条件,提出严格检疫、脱毒育苗、隔离建园、病虫防治、清除病树、加强宣传等综合防治措施.%This paper summarized main damage character,transmission manner and occurrence conditions of citrus Huan-glongbing and proposed control measures,including strict quarantine,detoxifying nursery of Virus-free seedlings,deVelop-ment of pathogen-isolated orchard,control of diseases and pests and strengthening propaganda.

  20. Detection of Pathogens Causing Citrus Black Spot of Guanxi Honey Pomelo by Nested PCR%巢式PCR检测琯溪蜜柚黑斑病病原菌

    Institute of Scientific and Technical Information of China (English)

    郑域茹; 罗金水; 张汉荣; 卢松茂; 林智明; 王宏毅; 李美桂

    2013-01-01

    Citrus black spot is a fungal disease in most Guanxi honey pomelo. By using the specific primers, a unique 487 bp band was obtained by PCR amplification from genomic DNA of the pathogen causing citrus black spot of Guanxi honey pomelo and the method could accurately distinguish the honey pomelo black spot pathogen from the other disease pathogens of Sphaceloma fawcetti Jenk, Colletotrichum gleosporioides Penz and Mycosphaerella cirri White-Side in Guanxi honey pomelo. The sensitivity was determined by nested PCR. For the genomic DNA of honey pomelo black spot pathogen, the sensibility of nested PCR reached 100 fg/μL, 100 times higher than that of routine PCR. For the DNA of diseased tissues, the sensibility of nested PCR reached 100μg of DNA sample. Through nested PCR assay, the pathogen of honey pomelo black spot could be specifically detected form diseased and symptom latent infection honey pomelo tissues with the detection rate of 96.67% and 90%, respectively.%利用特异性引物从琯溪蜜柚黑斑病菌基因组DNA中扩增出一条分子量为487 bp的特异性条带,准确地与疮痂病、炭疽病和黄斑病菌等蜜柚常发性真菌病害区分开.采用巢式PCR对该引物的检测灵敏度进行测定,结果显示,对于黑斑病菌基因组DNA,巢式PCR的检测灵敏度为100 fg/μL,灵敏度比常规PCR至少提高100倍;对于发病组织,巢式PCR可从病斑组织含量为100 μg的DNA样品中检测到黑斑病菌.采用巢式PCR检测技术,可从蜜柚的黑斑病显症组织和未显症组织特异性地检测到病原菌,且检出率分别为96.67%和90%.

  1. 枣缩果病初侵染链格孢菌的抗硫酸铜标记及稳定性%Resistance-Labeling and Stability of Jujube Shrunken-Fruit Disease Pathogen Alternaria alternata to Copper Sulfate

    Institute of Scientific and Technical Information of China (English)

    赵乐; 邢艺林; 李正楠; 郭金堂; 冉隆贤

    2016-01-01

    Objective]In order to determine the suitable agent and method for labeling Alternaria alternata,the pathogen of jujube shrunken-fruit disease,and to explore its primary infection period,the labeling system with copper sulfate in A. alternata was established,which will facilitate the study of infection mechanisms and pathogenicity of the pathogen,and effective management of the disease in the field. [Method]Copper sulfate was selected for the reagent of resistance-labeling in A. alternata wild type strain CN193 from the four fungicidal chemicals,i. e. copper sulfate,cobalt chloride,silver nitrate and cycloheximide by using inhibition zone method on PDA plate. With the inhibition method of spore germination,the mixture of conidial spore suspension with either 1. 0 mg·mL -1 ,1. 5 mg·mL -1 or 2. 0 mg·mL -1 concentration of the copper sulfate in a ratio of 1∶1 was dropped into concave slides. The germinated spores were scored after a 12 h incubation,and the initial concentration of copper sulfate was determined. A copper sulfate-resistant mutant strain CN193Cur was obtained by culturing the fungus on PDA medium containing copper sulfate from 1. 5 mg·mL -1 up to 4. 5 mg·mL -1 . The stability of the copper sulfate resistance of mutant CN193Cur was verified in the laboratory,and its infectivity was determined by pathogenicity test in a jujube plantation with inoculation of spore by spraying to the jujube flowers and stab-wounding on the surface of unripe jujube fruits,together with the analysis of BOX-PCR finger printing patterns.[Result]Copper sulfate had highly inhibitory effect on A. alternata while cobalt chloride and silver nitrate were less inhibitive,and cycloheximide was not inhibitive. The initial concentration of copper sulfate was set at 1. 5 mg·mL -1 , which produced a mutation rate of 12%,and the final concentration of copper sulfate in this study was 4. 5 mg·mL -1 . Inoculation tests showed that the mutant CN193Cur had the same pathogenicity as did

  2. Potencial de pseudomonas spp. fluorescentes para biocontrole de alternaria ricini em mamoneira Potential of fluorescent pseudomonas spp. For biological control of alternaria ricini on castorbean

    Directory of Open Access Journals (Sweden)

    Francisco de A.G. da Silva

    1998-06-01

    Full Text Available The potential of fluorescent Pseudomonas spp. to control Alternaria leaf spot on castorbean, caused by Alternaria ricini, was studied under greenhouse conditions. Two periods for antagonist applications were tested: 48h before and simultaneously to the pathogen inoculation. Among the antagonists tested JA4 and BJ22 were the most effectives showing disease severity reduction of 20.9% and 17.8% respectively, when applied simultaneously. The effect of Pseudomonas spp. on the micelial growth and sporulation was also studied throughout three different methods (funel, streak and celophane. Inhibition of micelial growth and sporulation was observed. There was no correlation between in vitro and in vivo data. Antibiosis was showed as a mode of action for Pseudomonas spp. in relation to Alternaria ricini. Ultrastructural studies confirmed the inhibition of spore germination by the bacteria.

  3. Trailers transporting oranges to processing plants move Asian citrus psyllids

    Science.gov (United States)

    Huanglongbing (citrus greening) is one of the most serious of citrus diseases. Movement of the disease occurs as a result of natural vector-borne infection and by movement of plant material. We demonstrate here that Diaphorina citri Kuwayama (vector of citrus greening pathogens) can be transported i...

  4. Degradation products of citrus volatile organic compounds (VOCs) acting as phagostimulants that increase probing behavior of Asian citrus psyllid

    Science.gov (United States)

    Volatile phytochemicals play a role in orientation by phytophagous insects. We studied antennal and behavioral responses of the Asian citrus psyllid, Diaphorina citri Kuwayama, vector of the citrus greening disease pathogen. Little or no response to citrus leaf volatiles was detected by electroanten...

  5. Overexpression of a modified plant thionin enhances disease resistance to citrus canker and huanglongbing (HLB, citrus greening)

    Science.gov (United States)

    Huanglongbing (HLB or citrus greening disease) caused by Candidatus Liberibacter asiaticus (Las) is a great threat to the United States citrus industry. Citrus canker is also an economically important disease associated with a bacterial pathogen (Xanthomonas citri). In this study, we characterized e...

  6. Preliminary Studies on Species and Distribution of Citrus Viroids in China

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-feng; ZHOU Chang-yong; TANG Ke-zhi; LAN Jian-qiang; ZHOU Yan; LI Zhon-gan

    2008-01-01

    Citrus viroids are the small but economically important RNA pathogens.For investigating their occurrence and distribution in China,65 viroid samples collected from 8 major citrus cultivated regions were evaluated using one-step or multiplex one-step RT-PCR and biological indexing for specifically detection of Citrus exocortis viroid (CEVd),Citrus bent leaf viroid (CBLVd),Hop stunt viroid (HSVd),Citrus viroid-ⅢI (CVd-Ⅲ) and Citrus viroid-Ⅳ (CVd-Ⅳ).The results showed that there were at least 4 kinds of citrus viroids (CEVd,CBLVd,HSVd,and CVd-Ⅲ) on citrus trees in China.Most of the infected citrus plants harbored more than one viroid species,and two plants were infected with up to 4 citrus viroids.Sweet orange was more frequently infected by viroids than other citrus varieties.It is the preliminary report on the species and distribution of citrus viroids in China.

  7. Comparison of antifungal activities of Vietnamese citrus essential oils.

    Science.gov (United States)

    Van Hung, Pham; Chi, Pham Thi Lan; Phi, Nguyen Thi Lan

    2013-03-01

    Citrus essential oils (EOs) are volatile compounds from citrus peels and widely used in perfumes, cosmetics, soaps and aromatherapy. In this study, inhibition of citrus EOs extracted from Vietnamese orange (Citrus sinensis), mandarin (Citrus reticulata Blanco), pomelo (Citrus grandis Osbeck) and lime (Citrus aurantifolia Swingle) on the growth of plant pathogenic fungi, Mucor hiemalis, Penicillium expansum and Fusarium proliferatum was investigated. The EOs of the citrus peels were obtained by cold-pressing method and the antifungal activity of EOs was evaluated using the agar dilution method. The results show that the EOs had significant antifungal activity. Lime EO was the best inhibitor of M. hiemalis and F. proliferatum while pomelo EO was the most effective against P. expansum. These results indicate that citrus EOs can be used as antifungal natural products in the food, pharmaceutical and cosmetic industries.

  8. Inhibition Effect of Extract Liquids from Chinese Herbal Medicines on Three Pathogens of Citrus Disease%中草药提取液对3种柑橘病原菌的抑制作用

    Institute of Scientific and Technical Information of China (English)

    刘畅; 任艳芳; 何俊瑜; 张兰兰; 尹国胜

    2011-01-01

    为了对中草药提取物应用于水果保鲜领域和开发新型植物源农药提供理论基础和依据,在中药质量浓度为0.05g/mL条件下,测定19种中草药水提物对3种来自柑橘采后病害的病原菌意大利青霉(Penicillium italicum Wehmer)、指状青霉(Penicillium digitatum Sacc.)和柑橘链格孢(Alternaria citri Ellis et Pierce)的抑菌效果.结果表明:同一种中药对不同病原菌及不同中药对同一病原菌的抑制作用存在差异.19种中草药水提物中,黄连对3种病原菌的综合抑菌率最高,为98.37%,且黄连提取物对意大利青霉,指状青霉,柑橘链格孢的最小抑菌浓度(MIC)分别为:0.2,0.025,0.05g/mL.而白芥子对意大利青霉以及桃仁、茯苓和玄参对指状青霉的生长则具有不同程度的促进作用.%The inhibition effect of 19 extract liquids with 0. 05 g/mL concentration from Chineae herbal medicines on Penicillium italicum. Penicillium digitatum and Alternaria citri of citrua diseasea was determined to provide the theoretical basis for application of Chineae herbal medicine extract in fruit preaervation and development of new batanical pesticiden. The results showed that there was difference in inhibition effect of the same extract liquid against different pathogens and inhibition effect of different extract liquids against the same pathogen , the comprehenaive inhibition rate of Coptis chinensis extract liquid against three pathogens reached 98. 37 % , the minimal inhibitony concentra tion of Coptis chinensis extract liquid against Penicillium italicum , Penicillium digitatum and Alternaria citri was 0 . 2 , 0. 025 and 0. 05 g/mL respectively , Sinapis alba extract liquid could promote growth of Peniciltium italicum , and liquida extracted from Prunus persica , Poria cocos and Scrophularia ningpoensis could promote growth of Penicillium digitatum to varying degrees.

  9. Citrus pulp for cattle.

    Science.gov (United States)

    Arthington, John D; Kunkle, William E; Martin, Amy M

    2002-07-01

    Citrus pulp is classified as an energy concentrate by-product feed. Citrus by-products fed to beef cattle include citrus molasses, citrus meal, wet citrus pulp, dried citrus pulp, and pelleted citrus pulp; however, in current production systems, pulp (wet, dry, and pelleted) is the only by-product commonly used. Citrus pulp production in the United States is limited to specific subtropical regions, of which south central Florida remains the largest with additional production in California and Texas.

  10. Studies on Alternaria allergens. I. Isolation of allergens from Alternaria tenuis and Alternaria solani.

    Science.gov (United States)

    Vijay, H M; Huang, H; Young, N M; Bernstein, I L

    1979-01-01

    Extracts of Alternaria tenuis and Alternaria solani were separated into dialyzable (molecular weight less than 10,000) and non-dialyzable forms. The latter was further fractionated by gel filtration through Sephadex G-100 followed by ion-exchange chromatography on DEAE-cellulose. The dialyzable material was fractionated by gel filtration through Sephadex G-50. The allergenic activities of the fractions obtained from the A. tenuis extract was measured in vitro by the radioallergosorbent test assay and the allergenic potency was measured by radioallergosorbent test inhibition assay. Allergenic activity was detected in most of the non-dialyzable fractions, the majority of the activity being in the last G-100 fraction (MW approximately 20,000) which was predominantly protein in nature. The same component may be responsible for the activity found in the dialyzate and its first G-50 fraction since the immunodiffusion studies indicated that the last G-100 fraction has antigenic components in common with those of the first G-50 fraction. In addition, cross-reactions between A. tenuis and A. solani extracts show that the two species share common antigenic determinants.

  11. Arbuscular mycorrhiza reduces susceptibility of tomato to Alternaria solani.

    Science.gov (United States)

    Fritz, Maendy; Jakobsen, Iver; Lyngkjaer, Michael Foged; Thordal-Christensen, Hans; Pons-Kühnemann, Jörn

    2006-09-01

    Mycorrhiza frequently leads to the control of root pathogens, but appears to have the opposite effect on leaf pathogens. In this study, we studied mycorrhizal effects on the development of early blight in tomato (Solanum lycopersicum) caused by the necrotrophic fungus Alternaria solani. Alternaria-induced necrosis and chlorosis of all leaves were studied in mycorrhizal and non-mycorrhizal plants over time course and at different soil P levels. Mycorrhizal tomato plants had significantly less A. solani symptoms than non-mycorrhizal plants, but neither plant growth nor phosphate uptake was enhanced by mycorrhizas. An increased P supply had no effect on disease severity in non-mycorrhizal plants, but led to a higher disease severity in mycorrhizal plants. This was parallel to a P-supply-induced reduction in mycorrhiza formation. The protective effect of mycorrhizas towards development of A. solani has some parallels to induced systemic resistance, mediated by rhizobacteria: both biocontrol agents are root-associated organisms and both are effective against necrotrophic pathogens. The possible mechanisms involved are discussed.

  12. The effects of citrus extract (Citrox©) on the naturally occurring microflora and inoculated pathogens, Bacillus cereus and Salmonella enterica, in a model food system and the traditional Greek yogurt-based salad Tzatziki.

    Science.gov (United States)

    Tsiraki, Maria I; Savvaidis, Ioannis N

    2016-02-01

    The antimicrobial effect of citrus extract (at 1 mL/kg [TC1] and 2 mL/kg [TC2]) on the naturally occurring microflora and inoculated pathogens (Bacillus cereus and Salmonella enterica, at ca. 6 log cfu/g) in the traditional Greek yogurt-based salad Tzatziki during storage under vacuum at 4 or 10 °C was examined. We also examined the effect of citrus extract (Citrox(©)) against the two aforementioned pathogens in tryptic soy broth (TSB). Of the two treatments, TC2 yielded the lowest yeast counts, irrespective of temperature, resulting in approximately 2 (4 °C) and 3 (10 °C) log reductions on the final day of storage (70 and 30 days, respectively). Although panelists preferred the TC1-treated salad, the TC2-treated product was sensorily acceptable. Therefore, at the concentrations used, Citrox had no negative sensorial effect on the Tzatziki. During storage, the Bacillus populations in the Citrox-treated Tzatziki samples progressively decreased, showing major declines from days 12 and 28 (at 10 and 4 °C, respectively). Citrox, especially at 2 mL/kg, had a significant effect on the survival of B. cereus. S. enterica showed major declines in all untreated Tzatziki samples from day 0-70 (4 °C) and from day 0-30 (10 °C), with averages of 2.5 and 2.8 log cfu/g, respectively. The results indicate that Citrox (at 1 and 2 mL/kg) is effective, from a safety standpoint, for reducing Bacillus and Salmonella spp. in Tzatziki. In addition, 2% citrus extract also showed a higher inhibitory effect against B. cereus and S. enterica grown in TSB than 1% citrus extract. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Pathogenicity of Alternaria tenuissima HZ-1 to broadleaf weeds and its safety on crops%极细链格孢菌HZ-1对阔叶杂草的致病性及对作物的安全性评价

    Institute of Scientific and Technical Information of China (English)

    朱海霞; 马永强; 程亮; 郭青云

    2016-01-01

    采用形态学结合分子鉴定的方法,对生防潜力菌株HZ-1进行分类学鉴定,通过菌株发酵液致病性测定,评价该菌株对5种阔叶杂草的除草活性,采用盆栽生测法评价其对青海省主栽作物的安全性.结果表明,HZ-1为极细链格孢菌(Alternaria tenuissima),菌株发酵液对猪秧秧(Galium aparine)、刺儿菜[Cephalano-plos setosum(Willd.)Kitam]、藜(Chenopodium album)、冬葵(Malva crispa)、酸模叶蓼(Polygonum lapathifolium L.)表现出不同程度的致病作用,尤其对猪秧秧、藜致病效果最为突出.安全性评价结果显示,该菌株除对春油菜有轻微影响外,对春小麦、蚕豆、豌豆和青稞4种作物相对安全.综上,HZ-1可作为防除猪殃殃、藜等阔叶杂草生物除草剂的候选菌株.%Strain HZ-1 was identified through morphology observation and sequence analysis. The herbicidal activity of HZ-1 against 5 broadleaf weeds was evaluated by the pathogenicity of fermentation broth, and its safety to major crops in Qinghai was tested by pot bioassay. It was shown that strain HZ-1 was identified as Alternaria tenuissima. The fermentation broth of strain HZ-1 exhibited varied pathogenicity to Galium aparine, Cephalanoplos setosum ( Willd. ) Kitam, Chenopodium album, Malva crispa, Polygonum lapathifolium, and within these 4 species, the pathogenicity to Galium aparine and Chenopodium album was more severe. Strain HZ-1 was safe to major crops ex-cept spring rape. In general, strain HZ-1 was candidate of microbial herbicide against broadleaf weeds such as Gali-um aparine and Chenopodium album.

  14. Alternaria alternata infection associated osteomyelitis of maxilla: A rare disease entity

    Directory of Open Access Journals (Sweden)

    Vidhi Chhabra

    2013-01-01

    Full Text Available Alternaria alternata is one of the rarest fungi associated with paranasal sinusitis. Alternaria species are pigmented (also known as dematiaceous or phaeoid filamentous fungi, which are well-known soil saprophytes and plant pathogens that infrequently cause infection in humans mainly, cutaneous lesions. We present a case of osteomyelitis of maxilla caused by a rare fungus- A. alternata in a diabetic patient with poor glycemic control who was successfully treated with antifungal and surgical debridement over the period of 6 months.

  15. 贡柑黑腐病病原菌的分子鉴定%Pathogen Identification of Black Rot of Gonggan

    Institute of Scientific and Technical Information of China (English)

    覃旭; 邓明学; 阳廷密; 谭有龙; 张素英; 门友均; 唐明丽; 张戈壁

    2012-01-01

    Black rot of gonggan citrus was a new disease occurred in recent years. This disease caused rapid withering of young shoot tips, massive abscission of young leaves, resulting in reduced yield. In this study, the pathogen of this disease was isolated, and identified by analysis of the rDNA-ITS sequence. The results showed that the pathogen was an Alternaria fungus. The sequence of its rDNA-ITS shared a 99% of identity with those of Alternaria brassicae (Berk ) Sacc. And Alternaria citri Ellis $- Everhart deposited in GenBank. The pathogen was finally identified as A. Citri based on the morphological characteristics and sequence of rDNA-ITS.%贡柑黑腐病是近年来在贡柑上发生的一种新型病害,该病害可导致嫩梢快速枯死,大量嫩叶脱落,严重影响树势和产量.本研究从病区采集发病枝叶,对贡柑黑腐病病原菌进行分离、纯化,并采用rDNA-ITS序列分析技术对其进行分子鉴定.结果表明,贡柑黑腐病病原菌为链格孢属Alternaria Nees真菌,rDNA-ITS序列与GenBank中芸薹链格孢菌A.brassicae (Berk.) Sacc.和柑桔链格孢菌A.citri Ellis et Everhart的ITS序列的同源性为99%.结合形态学特征,推断该病原菌为柑桔链格孢菌.

  16. Apparent tolerance to huanglongbing in citrus and citrus-related germplasm

    Science.gov (United States)

    In a Ft. Pierce, Florida field planting, growth and huanglongbing (HLB) severity were assessed as indicators of HLB-tolerance on progenies of 83 seed-source accessions of citrus and citrus-relatives from the Riverside, California genebank. The HLB-pathogen (Candidatus Liberibacter asiaticus) and vec...

  17. Phyllosticta citriasiana sp. nov., the cause of Citrus tan spot of Citrus maxima in Asia

    NARCIS (Netherlands)

    Wulandari, N.F.; To-anun, C.; Hyde, K.D.; Duong, L.M.; Gruyter, de J.; Meffert, J.P.; Groenewald, J.Z.; Crous, P.W.

    2009-01-01

    Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range o

  18. Phyllosticta citriasiana sp nov., the cause of Citrus tan spot of Citrus maxima in Asia

    NARCIS (Netherlands)

    Wulandari, N.F.; To-anun, C.; Hyde, K.D.; Duong, L.M.; de Gruyter, J.; Meffert, J.P.; Groenewald, J.Z.; Crous, P.W.

    2009-01-01

    Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range o

  19. Proteome Analysis for Defense Response of Apple Leaves Induced by Alternaria Blotch ,Alternaria alternata Apple Pathotype

    Institute of Scientific and Technical Information of China (English)

    Caixia Zhang; Zhuang Li; Liyi Zhang; Yi Tian; Guodong Kang; Ying Chen; Peihua Cong

    2012-01-01

    Apple (Ma/us domestica) is considered a model fruit plant owing to its world-wide economic importance,and a large number of cultivars dominate world fruit production.To date,the cultivation of apple has been limited by many kinds of fungal diseases,and among the many fungal diseases affecting apple trees,Alternaria blotch,the disease caused by Alternaria alternata apple pathotype,is spreading worldwide and results in severe negative effect on apple production.Currently,management of a fungal disease such as Alternaria blotch mainly through traditional chemical control agents instead of using resistant cultivars.As in apple,the molecular mechanism of disease resistance against A.altemata apple pathotype has not been illustrated clearly,although most of the genes have been identified in apple,little is known about the biological roles for each protein in that plant.Considering that apple Altemaria blotch is the usual diseases influencing apple production,further studies about the interaction mechanism between the pathogen and its host,particularly some host self-defense response mechanisms which closely related to the anti-disease properties of apple should be performed.In this work we aimed to generate fundamental insights into the plant' s defense responses to infection with Altemaria blotch using a proteomics approach,to aid in the development and breeding of high-quality disease-resistant apple varieties.One seedlings which derived from the cross of ‘Huacui’ and ‘Golden Delicious’,with highly resistant,were chosen to be hosts for this study.The sample leaves were inoculated with spore suspension of A.altemata apple pathotype,and the control samples were treated with water instead of inoculums.Following inoculation,the samples were harvested 48 h after inoculation.The whole experiment was repeated three times in order to get a reliable result.The total soluble protein extracts prepared using modified phenol-precipitation procedures.Total protein extracts

  20. 柑橘采后腐烂主要致病菌的分离鉴定及丁香精油对其抑制作用研究%Isolation and identification of dominant pathogen on citrus fruit and the antifungal effect of clove oil on these fungi

    Institute of Scientific and Technical Information of China (English)

    解淑慧; 邵兴锋; 王可; 张兴龙; 王鸿飞

    2013-01-01

    [Objective]Six strains of fungi were isolated from rotten citrus in Ninghai, Zhejiang province. [Method]Based on the traditional morphological identification method and rDNA -Internal transcribed spacer (ITS) analysis, [Resultjthese strains were identified as Penicillium digitatum, Alternaria citri, Cladosporium cladosporioides , Aspergillus sydowii, Sporidiobolus pararoseus and Pichia coribbica. Especially , P. digitatum and C. dados porioides were the main fungi, which caused the disease of fruit after harvest. Meanwhile, the antifungal effect of clove oil on those was studied in vitro. Clove oil showed obvious antifungal effect on P. digitatum and C. dadosporioides. The half maximal inhibitory concentration (EC50) were 2.51 mL·L-1 and 0.57 mL·L-1 respectively; the minimal inhibitory concentration (MIC) were 6 rnL·L-1 and 3 mL·L-1 respectively. [Conclusion]The results suggested that clove oil could be used to control the postharvest pathogens on citrus fruit.%[目的]为了确定浙江宁海本地柑橘优势腐败菌及丁香精油对其的抑菌效果,[方法]从自然腐烂的柑橘上分离优势菌,采用传统真菌形态学鉴定方法结合rDNA-ITS序列分析方法进行鉴定,并采用体外试验研究丁香精油对优势菌的抑菌效果.[结果]结果表明,浙江宁海本地柑橘分离所得6株真菌分别为指状青霉(Penicillium digitatum)、柑橘链格孢(Alternariac itri)、枝孢样枝孢霉(Cladosporium cladosporioides)、聚多曲霉[Aspergillus sydowii)、近玫色锁掷孢酵母(Sporidiobolus pararoseus)和卡利比克毕赤酵母(Pichiacaribbica);其中P.digitatum和C.cladosporioides是优势腐败菌;体外抑菌试验表明,丁香精油对P.digitatum和C.cladosporioides有较好的抑菌效果,抑制中浓度(EC50)分别为2.51 mL·L-1和0.57 mL·L-1;最小抑菌浓度(MIC)分别为6 mL· L-1和3 mL·L-1.[结论]丁香精油可以抑制柑橘采后主要病原菌的生长.

  1. Swainsonine biosynthesis genes in diverse symbiotic and pathogenic fungi

    Science.gov (United States)

    Swainsonine, a cytotoxic fungal alkaloid and a potential cancer therapy drug, is produced by the insect pathogen and plant symbiont, Metarhizium robertsii, the clover pathogen Slafractonia leguminicola, locoweed symbionts belonging to Alternaria sect. Undifilum, and a recently discovered morning glo...

  2. Java project on periodontal diseases: effect of vitamin C/calcium threonate/citrus flavonoids supplementation on periodontal pathogens, CRP and HbA1c

    NARCIS (Netherlands)

    A. Amaliya; M.L. Laine; B.G. Loos; U. van der Velden

    2015-01-01

    Objective To assess in a periodontally diseased rural population deprived from regular dental care and having poor dietary conditions, the effect of vitamin C/calcium threonate/citrus flavonoids (VitC/Ca/Fl) supplementation on subgingival microbiota and plasma levels of vitamin C, HbA1c and hsCRP. M

  3. All five host-range variants of Xanthomonas citri carry one pthA homolog with 17.5 repeats that determines pathogenicity on citrus, but none determine host-range variation.

    Science.gov (United States)

    Al-Saadi, Abdulwahid; Reddy, Joseph D; Duan, Yong P; Brunings, Asha M; Yuan, Qiaoping; Gabriel, Dean W

    2007-08-01

    Citrus canker disease is caused by five groups of Xanthomonas citri strains that are distinguished primarily by host range: three from Asia (A, A*, and A(w)) and two that form a phylogenetically distinct clade and originated in South America (B and C). Every X. citri strain carries multiple DNA fragments that hybridize with pthA, which is essential for the pathogenicity of wide-host-range X. citri group A strain 3213. DNA fragments that hybridized with pthA were cloned from a representative strain from all five groups. Each strain carried one and only one pthA homolog that functionally complemented a knockout mutation of pthA in 3213. Every complementing homolog was of identical size to pthA and carried 17.5 nearly identical, direct tandem repeats, including three new genes from narrow-host-range groups C (pthC), A(w) (pthAW), and A* (pthA*). Every noncomplementing paralog was of a different size; one of these was sequenced from group A* (pthA*-2) and was found to have an intact promoter and full-length reading frame but with 15.5 repeats. None of the complementing homologs nor any of the noncomplementing paralogs conferred avirulence to 3213 on grapefruit or suppressed avirulence of a group A* strain on grapefruit. A knockout mutation of pthC in a group C strain resulted in loss of pathogenicity on lime, but the strain was unaffected in ability to elicit an HR on grapefruit. This pthC- mutant was fully complemented by pthA, pthB, or pthC. Analysis of the predicted amino-acid sequences of all functional pthA homologs and nonfunctional paralogs indicated that the specific sequence of the 17th repeat may be essential for pathogenicity of X. citri on citrus.

  4. Nonhost-specific phytotoxicity of the polyketide-derived toxin solanapyrone A produced by Ascochyta rabiei and Alternaria solani

    Science.gov (United States)

    Solanapyrone A is a polyketide-derived metabolite produced by Ascochyta rabiei and Alternaria solani, which are the most destructive necrotrophic pathogens of chickpea and potato/tomato, respectively. They belong to the Order Pleosporales within the Class Dothideomycetes, but are phylogenetically di...

  5. Infectopyrone, a potential mycotoxin from Alternaria infectoria

    DEFF Research Database (Denmark)

    Larsen, Thomas Ostenfeld; Perry, N.B.; Andersen, Birgitte

    2003-01-01

    A new metabolite, infectopyrone (1), has been isolated from the filamentous fungus Alternaria infectoria. The structure of 1 was elucidated by analysis of 2D NMR spectroscopic data. Compound 1 is an alpha-pyrone resembling known toxins, and is a useful phenotaxonomic marker for the A. infectoria ...

  6. Infectopyrone, a potential mycotoxin from Alternaria infectoria

    DEFF Research Database (Denmark)

    Larsen, Thomas Ostenfeld; Perry, N.B.; Andersen, Birgitte

    2003-01-01

    A new metabolite, infectopyrone (1), has been isolated from the filamentous fungus Alternaria infectoria. The structure of 1 was elucidated by analysis of 2D NMR spectroscopic data. Compound 1 is an alpha-pyrone resembling known toxins, and is a useful phenotaxonomic marker for the A. infectoria ...

  7. Citrus leprosis research update

    Science.gov (United States)

    Citrus leprosis is one of the oldest citrus diseases, but is also one of the most important emerging citrus diseases in South and Central America, and it is apparently spreading northward towards the U.S. Research in our labs and by others has shown that citrus leprosis disease is caused by a compl...

  8. Mycotoxin Production in Liquid Culture and on Plants Infected with Alternaria spp. Isolated from Rocket and Cabbage

    Science.gov (United States)

    Siciliano, Ilenia; Ortu, Giuseppe; Gilardi, Giovanna; Gullino, Maria Lodovica; Garibaldi, Angelo

    2015-01-01

    Fungi belonging to the genus Alternaria are common pathogens of fruit and vegetables with some species able to produce secondary metabolites dangerous to human health. Twenty-eight Alternaria isolates from rocket and cabbage were investigated for their mycotoxin production. Five different Alternaria toxins were extracted from synthetic liquid media and from plant material (cabbage, cultivated rocket, cauliflower). A modified Czapek-Dox medium was used for the in vitro assay. Under these conditions, more than 80% of the isolates showed the ability to produce at least one mycotoxin, generally with higher levels for tenuazonic acid. However, the same isolates analyzed in vivo seemed to lose their ability to produce tenuazonic acid. For the other mycotoxins; alternariol, alternariol monomethyl ether, altenuene and tentoxin a good correlation between in vitro and in vivo production was observed. In vitro assay is a useful tool to predict the possible mycotoxin contamination under field and greenhouse conditions. PMID:25751147

  9. Mycotoxin Production in Liquid Culture and on Plants Infected with Alternaria spp. Isolated from Rocket and Cabbage

    Directory of Open Access Journals (Sweden)

    Ilenia Siciliano

    2015-03-01

    Full Text Available Fungi belonging to the genus Alternaria are common pathogens of fruit and vegetables with some species able to produce secondary metabolites dangerous to human health. Twenty-eight Alternaria isolates from rocket and cabbage were investigated for their mycotoxin production. Five different Alternaria toxins were extracted from synthetic liquid media and from plant material (cabbage, cultivated rocket, cauliflower. A modified Czapek-Dox medium was used for the in vitro assay. Under these conditions, more than 80% of the isolates showed the ability to produce at least one mycotoxin, generally with higher levels for tenuazonic acid. However, the same isolates analyzed in vivo seemed to lose their ability to produce tenuazonic acid. For the other mycotoxins; alternariol, alternariol monomethyl ether, altenuene and tentoxin a good correlation between in vitro and in vivo production was observed. In vitro assay is a useful tool to predict the possible mycotoxin contamination under field and greenhouse conditions.

  10. Mycotoxin production in liquid culture and on plants infected with Alternaria spp. isolated from rocket and cabbage.

    Science.gov (United States)

    Siciliano, Ilenia; Ortu, Giuseppe; Gilardi, Giovanna; Gullino, Maria Lodovica; Garibaldi, Angelo

    2015-03-05

    Fungi belonging to the genus Alternaria are common pathogens of fruit and vegetables with some species able to produce secondary metabolites dangerous to human health. Twenty-eight Alternaria isolates from rocket and cabbage were investigated for their mycotoxin production. Five different Alternaria toxins were extracted from synthetic liquid media and from plant material (cabbage, cultivated rocket, cauliflower). A modified Czapek-Dox medium was used for the in vitro assay. Under these conditions, more than 80% of the isolates showed the ability to produce at least one mycotoxin, generally with higher levels for tenuazonic acid. However, the same isolates analyzed in vivo seemed to lose their ability to produce tenuazonic acid. For the other mycotoxins; alternariol, alternariol monomethyl ether, altenuene and tentoxin a good correlation between in vitro and in vivo production was observed. In vitro assay is a useful tool to predict the possible mycotoxin contamination under field and greenhouse conditions.

  11. Alternaria alternata invasive fungal infection in a patient with Fanconi's anemia after an unrelated bone marrow transplant.

    Science.gov (United States)

    Ferreira, Isabelina de Sousa; Teixeira, Gilda; Abecasis, Manuel

    2013-02-01

    Alternaria spp. have emerged as opportunistic pathogens particularly in immunosuppressed patients, such as bone marrow transplant recipients. The authors present a case of Alternaria alternata in a patient with Fanconi's anemia, who received antifungal prophylaxis with posaconazole after an unrelated bone marrow transplantation, followed by empirical antifungal treatment with caspofungin when persistent fever emerged until cutaneous lesions eventually appeared. At that time there were clinical reasons to assume that the patient had an infection with an emerging fungus. This consideration triggered a change of the antifungal therapy from caspofungin to liposomal amphotericin B. After collecting sufficient evidence for the presence of an invasive fungal infection by A. alternata and given the severity of neutropenia and other immunosuppression, oral posaconazole was added to liposomal amphotericin B. The course of disease in this case suggests a possibly synergistic interaction between liposomal amphotericin B and posaconazole when administered simultaneously to treat an invasive systemic infection by Alternaria spp. in immunocompromised patients.

  12. Antimicrobial Activity and Phytochemical Analysis of Citrus Fruit Peels -Utilization of Fruit Waste

    OpenAIRE

    K. Ashok Kumar; Narayani, M.; A. Subanthini; Jayakumar, M.

    2011-01-01

    Antibacterial activity of five different solvent extracts(ethyl acetate, acetone, ethanol, petroleum ether and water) prepared by soxhlet extractor from two citrus fruit peel (Citrus sinensis and Citrus limon) were screened against five pathogenic bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli , Klebsiella pneumonia and Salmonella typhi. The highest antibacterial potentiality was exhibited by the acetone peel extract of Citrus sinensis followed by the ethyl acetate peel e...

  13. Antifungal activity of chitosan(oligochitosan) on Geotrichum candidum and Alternaria citri of citrus and postharvest disease control%壳聚(寡)糖对柑橘酸腐、黑腐病菌的抑制作用及对采后病害的防治

    Institute of Scientific and Technical Information of China (English)

    王丽; 赵盼; 孟祥红

    2011-01-01

    In vitro,the pore germination,germ tube length and mycelial growth of the two fungi were used to evaluate to the effect of chitosan and oligochitosan. The effects of chitosan and ologochitosan on disease control were investigated by stab inoculation. The results showed that chitosan and oligochitosan at 10mg/mL almost completely inhibited the mycelial growth of the two fungi. Chitosan and oligochitosan at 0. 5mg/mL completely inhibited the spore germination and germ tube elongation of Geotrichum candidum. Moreover,2mg/mL of chitosan could completely inhibit the spore germination and germ tube elongation of Alternaria citri,but 2mg/mL of oligochitosan had a lower inhibitory effect. In vivo results showed that the control effect of chitosan and oligochitosan at 1% on fruit disease were better than lower concentration.%通过体外实验测定不同浓度的壳聚糖和壳寡糖对酸腐和黑腐病菌孢子萌发、芽管长度和菌丝生长的抑制作用;采用刺伤接种方法评价壳聚糖和壳寡糖对柑橘果实两种病害的防治作用。离体实验结果表明,壳聚糖和壳寡糖浓度为10mg/mL时几乎完全抑制两种病原菌的菌丝生长;浓度为0.5mg/mL壳聚糖和壳寡糖能完全抑制柑橘酸腐病菌(Geotrichum candidum)孢子萌发和芽管伸长的效果,而2mg/mL的壳聚糖才能完全抑制柑橘黑腐病菌(Alternaria citri)孢子萌发和芽管伸长,但相同浓度的壳寡糖抑制A.citri的孢子萌发和芽管伸长效果较差。体内实验结果表明,其病害防治效果具有浓度依赖性,高浓度(1%)的壳聚糖和壳寡糖对果实病害的防治效果较低浓度的防治效果好。

  14. Signaling pathways in a Citrus EST database

    Directory of Open Access Journals (Sweden)

    Angela Mehta

    2007-01-01

    Full Text Available Citrus spp. are economically important crops, which in Brazil are grown mainly in the State of São Paulo. Citrus cultures are attacked by several pathogens, causing severe yield losses. In order to better understand this culture, the Millenium Project (IAC Cordeirópolis was launched in order to sequence Citrus ESTs (expressed sequence tags from different tissues, including leaf, bark, fruit, root and flower. Plants were submitted to biotic and abiotic stresses and investigated under different development stages (adult vs. juvenile. Several cDNA libraries were constructed and the sequences obtained formed the Citrus ESTs database with almost 200,000 sequences. Searches were performed in the Citrus database to investigate the presence of different signaling pathway components. Several of the genes involved in the signaling of sugar, calcium, cytokinin, plant hormones, inositol phosphate, MAPKinase and COP9 were found in the citrus genome and are discussed in this paper. The results obtained may indicate that similar mechanisms described in other plants, such as Arabidopsis, occur in citrus. Further experimental studies must be conducted in order to understand the different signaling pathways present.

  15. The pathogenicity determinant of Citrus tristeza virus causing the seedling yellows syndrome maps at the 3'-terminal region of the viral genome.

    Science.gov (United States)

    Albiach-Marti, Maria R; Robertson, Cecile; Gowda, Siddarame; Tatineni, Satyanarayana; Belliure, Belén; Garnsey, Stephen M; Folimonova, Svetlana Y; Moreno, Pedro; Dawson, William O

    2010-01-01

    Citrus tristeza virus (CTV) (genus Closterovirus, family Closteroviridae) causes some of the more important viral diseases of citrus worldwide. The ability to map disease-inducing determinants of CTV is needed to develop better diagnostic and disease control procedures. A distinctive phenotype of some isolates of CTV is the ability to induce seedling yellows (SY) in sour orange, lemon and grapefruit seedlings. In Florida, the decline isolate of CTV, T36, induces SY, whereas a widely distributed mild isolate, T30, does not. To delimit the viral sequences associated with the SY syndrome, we created a number of T36/T30 hybrids by substituting T30 sequences into different regions of the 3' half of the genome of an infectious cDNA of T36. Eleven T36/T30 hybrids replicated in Nicotiana benthamiana protoplasts. Five of these hybrids formed viable virions that were mechanically transmitted to Citrus macrophylla, a permissive host for CTV. All induced systemic infections, similar to that of the parental T36 clone. Tissues from these C. macrophylla source plants were then used to graft inoculate sour orange and grapefruit seedlings. Inoculation with three of the T30/T36 hybrid constructs induced SY symptoms identical to those of T36; however, two hybrids with T30 substitutions in the p23-3' nontranslated region (NTR) (nucleotides 18 394-19 296) failed to induce SY. Sour orange seedlings infected with a recombinant non-SY p23-3' NTR hybrid also remained symptomless when challenged with the parental virus (T36), demonstrating the potential feasibility of using engineered constructs of CTV to mitigate disease.

  16. Mitogen-activated protein kinase signaling pathways of the tangerine pathotype of Alternaria alternata

    Directory of Open Access Journals (Sweden)

    Kuang-Ren Chung

    2013-06-01

    Full Text Available Mitogen-activated protein kinase (MAPK- mediated signaling pathways have been known to have important functions in eukaryotic organisms. The mechanisms by which the filamentous fungus Alternaria alternata senses and responds to environmental signals have begun to be elucidated. Available data indicate that A. alternata utilizes the Fus3, Hog1 and Slt2 MAPK-mediated signaling pathways, either separately or in a cooperative manner, for conidia formation, resistance to oxidative and osmotic stress, and pathogenesis to citrus. This review provides an overview of our current knowledge of MAPK signaling pathways, in conjunction with the two-component histidine kinase and the Skn7 response regulator, in the tangerine pathotype of A. alternata.

  17. Efficiency and cost of chemical control of alternaria brown spot

    OpenAIRE

    Adimara Bentivoglio Colturato; Tatiana Paulossi; Wilson Story Venâncio; Edson Luiz Furtado

    2009-01-01

    A mancha de alternaria, causada por Alternaria alternata f. sp. citri, afeta tangelos Minneola, tangerinas Dancy, tangores Murcote e, menos freqüentemente, tangelos Orlando, tangerinas Novas, Lees e Sunburst. Esta doença causa desfolha grave, queda de frutos e manchas nas frutas. O objetivo deste trabalho foi estabelecer o melhor fungicida e a melhor dose para o controle da mancha marrom de alternaria. O delineamento experimental foi de parcelas subdivididas em blocos, com 10 tratamentos prin...

  18. Characterisation of Alternaria species-groups associated with core rot of apples in South Africa

    DEFF Research Database (Denmark)

    Serdani, M.; Kang, J.C.; Andersen, Birgitte

    2002-01-01

    Alternaria core rot of red apple cultivars is a serious post-harvest disease in South Africa. Thirty isolates of Alternaria spp. previously isolated from apple, together with reference isolates of A. alternata and A. infectoria, were characterised and grouped according to their sporulation patterns...... and conidial morphology. Isolates were identified as belonging to A. arborescens, A. infectoria and A. tenuissima species-groups. The isolates were also analysed for production of mycotoxins and other secondary metabolites and their cultural characteristics on DRYES medium were recorded. Apple fruit were...... the other species-groups, as all isolates had a distinction of 35 base pair insertions and 6 base pair deletions in the ITS regions. The results obtained in the present study showed that the major pathogens associated with core rot disease of Top Red apples in South Africa belong to the A. tenuissima...

  19. Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), Vector of Huanglongbing Pathogens.

    Science.gov (United States)

    Patt, Joseph M; Stockton, Dara; Meikle, William G; Sétamou, Mamoudou; Mafra-Neto, Agenor; Adamczyk, John J

    2014-11-19

    Asian citrus psyllid (Diaphorina citri) transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid's host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid's primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal.

  20. Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae, Vector of Huanglongbing Pathogens

    Directory of Open Access Journals (Sweden)

    Joseph M. Patt

    2014-11-01

    Full Text Available Asian citrus psyllid (Diaphorina citri transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid’s host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid’s primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal.

  1. Resposta de diferentes genótipos de tangerinas e seus híbridos à inoculação in vitro e in vivo de Alternaria alternata Response of different tangerine varieties and hybrids to in vitro and in vivo inoculation of Alternaria alternata

    Directory of Open Access Journals (Sweden)

    Fernando Alves Azevedo

    2010-09-01

    Full Text Available A severidade da mancha-marrom de alternária nos pomares brasileiros de tangerinas tem causado sérias preocupações aos citricultores, devido aos prejuízos em plantios comerciais de variedades suscetíveis, como a tangerina Ponkan e o tangor Murcott. Para avaliar a resposta de diferentes genótipos ao fungo, foram realizadas inoculações de Alternaria alternata in vitro e in vivo, em 54 diferentes genótipos de tangerinas e seus híbridos, selecionados no Banco Ativo de Germoplasma de Citros do Centro APTA Citros Sylvio Moreira, do Instituto Agronômico, em Cordeirópolis-SP, visando a encontrar variedades resistentes. Para isso, inicialmente, testes de patogenicidade foram realizados com dez isolados de A. alternata para a seleção dos mais agressivos. Posteriormente, foram realizadas inoculações em folhas destacadas e em plântulas e, aos dois (in vitro e três (in vivo dias após, fez-se a contagem do número de lesões/folha e a estimativa da severidade da doença com auxílio de escala diagramática (in vivo. A maior parte dos genótipos apresentou sintomas da doença, porém com diferentes graus de suscetibilidade. Genótipos como a tangerina Sul da África e o tangelo Orlando foram os mais suscetíveis. Por outro lado, o grupo das satsumas e mexericas, assim como algumas tangerinas mostraram-se resistentes, indicando novas opções para a citricultura nacional.The confirmation of a new disease in the Brazilian tangerine orchards, the alternaria brown spot, has been concerning citrus growers because of the serious damages to commercial crops of susceptible varieties, such as Ponkan tangerine and Murcott tangor. In this research, in vitro and in vivo inoculations of Alternaria alternata fungus were held in 54 different varieties of the tangerine group selected from the Citrus Germoplasm Bank of Centro APTA Citros Sylvio Moreira, Instituto Agronomico, Cordeirópolis, State of São Paulo, Brazil, aiming to find varieties with more

  2. EVALUATION OF DISEASE RESISTANCE POTENTIAL OF SEVEN POTATO GENOTYPES AGAINST EARLY BLIGHT CAUSED BY Alternaria tenuissima UNDER GREENHOUSE CONDITIONS

    Directory of Open Access Journals (Sweden)

    Hamid Reza Mirkarimi

    2013-07-01

    Full Text Available Early blight of potato was caused by various species of genus Alternaria, the disease has a prominent role in reducing crop yields in most of the countries, especially in Iran. Various studies has been conducted for the finding out the information regarding the diversity of pathogen and estimation of damage caused by genus Alternaria tenuissima in Iran, but the information regarding the resistance against this fungal pathogen in various genotype of potatoes are in scarcity. Seven isolates of potato were obtained from the National Plant Gene Bank of Iran. Amongst these seven, on the basis of mean comparison curve progress Cosmos was recognized as the most sensitive genetic samples while the samples Armida was reported as a most resistant to the disease. Other cultivars showed different levels of resistance against this pathogen.

  3. 柑橘黄龙病病原分化及发生规律研究进展%The Research Progress of Citrus Huanglongbing on Pathogen Diversity and Epidemiology

    Institute of Scientific and Technical Information of China (English)

    柏自琴; 周常勇

    2012-01-01

    Huanglongbing (HLB) is a highly destructive disease to citrus industry. The pathogen, Candidates Liberibacter spp., is hardly cultured in vitro. This review focused on the lastest research progress in pathogen characteristics and intraspecific differentiations, occurrence features in the field such as incubation period, spatial-temporal dynamics, and disease cycle. Then the epidemic factors mainly in terms of host plants, vector and survival condition were discussed.%由韧皮部难培养细菌(Candidatus Liberibacter spp.)引起的柑橘黄龙病是一种毁灭性柑橘病害.主要综述了柑橘黄龙病菌的特性及种内分化新进展,病害的潜育期、时空动态及病害循环等田间发生特点,并从寄主植物、传播介体、生存条件等角度对影响病害流行的因素等进行了分析.

  4. Antimicrobial Activity and Phytochemical Analysis of Citrus Fruit Peels -Utilization of Fruit Waste

    Directory of Open Access Journals (Sweden)

    K. Ashok kumar

    2011-06-01

    Full Text Available Antibacterial activity of five different solvent extracts(ethyl acetate, acetone, ethanol, petroleum ether and water prepared by soxhlet extractor from two citrus fruit peel (Citrus sinensis and Citrus limon were screened against five pathogenic bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli , Klebsiella pneumonia and Salmonella typhi. The highest antibacterial potentiality was exhibited by the acetone peel extract of Citrus sinensis followed by the ethyl acetate peel extract of Citrus limon. The peel extract of Citrus sinensis and Citrus limon can be considered to be as equally potent as the antibiotics, such as metacillin and penicillin. MICs were tested at concentrations ranging from 50-6.25 mg/ml as wells as their MBCs. The phytochemical analysis of the citrus peel extracts showed the presence of flavonoids, saponins, steroids, terpenoids, tannins and alkaloids

  5. Pathogenic mycoflora on carrot seeds

    Directory of Open Access Journals (Sweden)

    Bogdan Nowicki

    2013-12-01

    Full Text Available Altogether 300 seed samples were collected during 9 years in 8 regions of Poland and the fungi Were isolated and their pathogenicity to carrot seedlings was examined. Alternaria rudicina provcd to be the most important pathogen although. A. alternata was more common. The other important pathogens were Fusarium spp., Phoma spp. and Botrytis cinerea. The infection of carrot seeds by A. radicina should be used as an important criterium in seed quality evaluation.

  6. Pathogenic mycoflora on carrot seeds

    OpenAIRE

    Bogdan Nowicki

    2013-01-01

    Altogether 300 seed samples were collected during 9 years in 8 regions of Poland and the fungi Were isolated and their pathogenicity to carrot seedlings was examined. Alternaria rudicina provcd to be the most important pathogen although. A. alternata was more common. The other important pathogens were Fusarium spp., Phoma spp. and Botrytis cinerea. The infection of carrot seeds by A. radicina should be used as an important criterium in seed quality evaluation.

  7. Fungitoxic activity of 12 essential oils against four postharvest citrus pathogens: chemical analysis of thymus capitatus oil and its effect in subatmospheric pressure conditions.

    Science.gov (United States)

    Arras, G; Usai, M

    2001-07-01

    The fungitoxic activity against Penicillium digitatum, Penicillium italicum, Botrytis cinerea, and Alternaria citri of 12 essential oils (EOs) distilled from medicinal plants is reported. The results of the in vitro trials show strong fungitoxic activity of Thymus capitatus (L.) Hofmgg EOs, which inhibited the growth of the four fungi at a concentration of 250 ppm (vol/vol). The other 11 essences reduced the development of the fungi from 95 to 9% at 250 ppm (vol/vol). The fungitoxic activity of T. capitatus EOs (75, 150, and 250 ppm) on healthy orange fruits, inoculated with P. digitatum (10(8) conidia ml(-1)) by spraying and placed in 10-liter desiccators, was weak at atmospheric pressure (3 to 10% inhibition at all three concentrations), while in vacuum conditions (0.5 bar), conidial mortality on the exocarp was high (90 to 97% at all three concentrations). These data proved not to be statistically different from treatments with thiabendazole-TBZ (2,000 ppm). Scanning electron microscope observations showed that T. capitatus EO vapors altered the morphology of P. digitatum hyphae and conidia. The gas-chromatographic analyses of thyme EO indicated that carvacrol was present at 81 to 83%, p-cymene at 4.5 to 5%, gamma-terpinene at 2.6 to 3.3%, caryophyllene at 1.5 to 1.6%, beta-myrcene at 1.6%, and linalool at 1.1 to 1.2%. Carvacrol proved to be the most important fungitoxic compound among the thyme EO constituents, but, unlike thyme EO, it caused alterations to the fruit at the concentration of 75 ppm.

  8. Presence of adhesive vesicles in the mycoherbicide Alternaria helianthi

    Science.gov (United States)

    Alternaria helianthi conidia have been shown to cause disease on common cocklebur. Conidia were applied to slides made hydrophobic by coating with dimethyldicholorosilane (mimics leaf surface), then rinsed and treated with FITC-Con A to stain the adhesive material. Alternaria helianthi coni...

  9. 3种柑橘病原真菌对苯醚菌酯和苯醚甲环唑敏感基线研究%Baseline sensitivities of three fungal pathogens of citrus to strobilurin fungicide and difenoconazole

    Institute of Scientific and Technical Information of China (English)

    侯欣; 陈国庆; 王兴红; 朱丽; 李红叶

    2013-01-01

    Melanose (Diaporthe citri),black spot (Guignardia citricarpa) and greasy spot (Mycospharella citri) of citrus have been becoming more and more serious and widespread,causing significant losses to the Chinese citrus industry by reducing yield and fruit quality in recent years.Although the improvement of cultural practices has the positive effect,application of fungicides is still the primary and effective means to control these diseases.Difenoconazole(belong to 14α-demethlylation inhibitors,DMIs) is a fungicide recently registered for use on citrus in China.ZJ0712 (belong to strobilurin,QoI),developed independently by our country,has a high potential in controlling citrus fungal diseases.The objective of this study was to establish the baseline sensitivity of these citrus fungal pathogens to these fungicides prior to their widespread use. Forty-eight single-spore strains of D.citri,46 strains of G.citricarpa and 50 strains of M.citri were collected from main citrus-producing regions in China.The effective dose to reduce mycelial growth or spore germination by 50% (EC50 values) of each strain was determined by using eight different concentrations of fungicides.The results demonstrated that the baseline sensitivities for mycelial growth of D.citri,G.citricarpa and M.citri to ZJ0712 were 0.003,0.011 and 0.035 μg/mL,respectively; to difenoconazole were 0.149,0.008 and 0.970 μg/mL,respectively.The baseline sensitivities for conidial germination of D.citri to ZJ0712 was 0.001 μg/mL,but > 25 μg/mL to difenoconazole. These results above indicated that the populations of D.citri,G.citricarpa and M.citri were sensitive to ZJ0712,and the populations of G.citricarpa and M.citri were sensitive to difenoconazole,implying widely potential usage of these fungicides in controlling the diseases above.Determination of the baseline sensitivities of D.citri,G.citricarpa and M.citri should also facilitate the detection and verification of pathogen resistance development to ZJ0712

  10. Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

    Institute of Scientific and Technical Information of China (English)

    SUN Hong; GAO Shushan; LI Xiaoming; LI Chunshun; WANG Bingui

    2013-01-01

    A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192,an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa,resulted in the isolation of nine known secondary metabolites,including four indole-diterpenoids:penijanthine A (1),paspaline (2),paspalinine (3),and penitrem A (4); three tricycloaltemarene derivatives:tricycloalternarene 3a (5),tricycloaltemarene lb (6),and tricycloalternarene 2b (7); and two altemariol congeners:djalonensone (8) and altemariol (9).The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature.The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum,with inhibition zone diameters of 8 and 9 mm,respectively,at 100 μ.g/disk.To the best of our knowledge,this is the first report on the secondary metabolites of mangrove-derived Alternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus Alternaria.

  11. Genetic Transformation in Citrus

    Directory of Open Access Journals (Sweden)

    Dicle Donmez

    2013-01-01

    Full Text Available Citrus is one of the world’s important fruit crops. Recently, citrus molecular genetics and biotechnology work have been accelerated in the world. Genetic transformation, a biotechnological tool, allows the release of improved cultivars with desirable characteristics in a shorter period of time and therefore may be useful in citrus breeding programs. Citrus transformation has now been achieved in a number of laboratories by various methods. Agrobacterium tumefaciens is used mainly in citrus transformation studies. Particle bombardment, electroporation, A. rhizogenes, and a new method called RNA interference are used in citrus transformation studies in addition to A. tumefaciens. In this review, we illustrate how different gene transformation methods can be employed in different citrus species.

  12. Alternethanoxins A and B, polycyclic ethanones produced by Alternaria sonchi , potential mycoherbicides for Sonchus arvensis biocontrol.

    Science.gov (United States)

    Evidente, Antonio; Punzo, Biancavaleria; Andolfi, Anna; Berestetskiy, Alexander; Motta, Andrea

    2009-08-12

    Alternaria sonchi is a fungal pathogen isolated from Sonchus arvensis and proposed as a biocontrol agent of this noxious perennial weed. Different phytotoxic metabolites were isolated from solid culture of the fungus. Two new polycyclic ethanones, named alternethanoxins A and B, were characterized using essentially spectroscopic and chemical methods. Tested by leaf disk-puncture assay on the fungal host plant and a number of nonhost plants, alternethanoxins A and B were shown to be phytotoxic, whereas they did not possess antimicrobial activity tested at 100 microg/disk. Hence, alternethanoxins A and B have potential as nonselective natural herbicides. Some structure-activity relationship observations were also made.

  13. Proteomic analysis of Alternaria alternata (Fr.) Keissler responds to COS fumigation.

    Science.gov (United States)

    Liu, Tao; Li, Li; Qu, Haixia; Zhan, Guoping; Liu, Bo; Wang, Yuejin

    2010-01-01

    Carbonyl sulfide (COS) is a new fumigant which has been a potential alternative to methyl bromide and phosphine in many applications. In this study, we investigated the fungitoxicity of COS towards the pathogen of pear black spot disease Alternaria alternata (Fr.) Keissler (A. alternata). Moreover, proteomic analysis and RT-PCR was performed and our results showed that during the fumigation, the regulation of 21 proteins in protein expression and mRNA accumulation levels is involved, which respond to growth inhibition caused by COS. These results provide new clues for the mechanism of the fungitoxicity of COS.

  14. First Record of Alternaria simsimi Causing Leaf Spot on Sesame (Sesamum indicum L.) in Korea.

    Science.gov (United States)

    Choi, Young Phil; Paul, Narayan Chandra; Lee, Hyang Burm; Yu, Seung Hun

    2014-12-01

    Leaf spot disease was observed in sesame (Sesamum indicum L.) during 2009 and 2010 in Korea. The pathogen was identified as Alternaria simsimi based on morphological and cultural characteristics. The morphological identification was well supported by phylogenetic analysis of the ribosomal DNA-internal transcribed spacer region. A. simsimi isolates caused spot symptoms on leaves and stems of sesame plants 2 wk after artificial inoculation, which were similar to those observed in the field. This is the first record of leaf spot disease in Korea caused by A. simsimi.

  15. Phytotoxic effects of metabolites from Alternaria euphorbiicola against its host plant Euphorbia heterophylla

    Directory of Open Access Journals (Sweden)

    Eduardo Vinícius Vieira Varejão

    2013-01-01

    Full Text Available A bioassay-guided fractionation of culture filtrates of the fungus Alternaria euphorbiicola, a pathogen of the weed Euphorbia heterophylla, led to the isolation of anhydromevalonolactone (1, tyrosol (2, (R-( - -mevalonolactone (3, and cycloglycylproline (4. When tested on the punctured leaves of the host plant, these compounds produced bleached lesions with dark brown margins at concentrations as low as 80 µM. When tested on the leaves of other relevant weeds, only cycloglycylproline showed selective activity against E. heterophylla. This is the first report on the isolation of phytotoxins from A. euphorbiicola and on the phytotoxicity of anhydromevalonolactone, (R-( - -mevalonolactone, and cycloglycylproline.

  16. Abscisic acid enhances resistance to Alternaria solani in tomato seedlings.

    Science.gov (United States)

    Song, Weiwei; Ma, Xinrong; Tan, Hong; Zhou, Jinyan

    2011-07-01

    The plant hormone abscisic acid (ABA) is an important regulator in many aspects of plant growth and development, as well as stress resistance. Here, we investigated the effects of exogenous ABA application on the interaction between tomato (Solanum lycopersicon L.) and Alternaria solani (early blight). Foliar spraying of 7.58 μM ABA was effective in reducing disease severity in tomato plants. Previously, increased activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) were observed in exogenous ABA-treated tomato leaves. Moreover, these enzyme activities were maintained at higher levels in ABA-pretreated and A. solani challenged tomato plants. Tomato defense genes, such as PR1, β-1, 3-glucanase (GLU), PPO, POD, and superoxide dismutase (SOD), were rapidly and significantly up-regulated by exogenous ABA treatment. Furthermore, a subsequent challenge of ABA-pretreated plants with the pathogen A. solani resulted in higher expression of defense genes, compared to water-treated or A. solani inoculated plants. Therefore, our results suggest that exogenous ABA could enhance disease resistance against A. solani infection in tomato through the activation of defense genes and via the enhancement of defense-related enzymatic activities.

  17. Evaluation of Alternaria mycotoxins in strawberries: quantification and storage condition.

    Science.gov (United States)

    Juan, Cristina; Oueslati, Souheib; Mañes, Jordi

    2016-05-01

    Alternariol (AOH), alternariol methyl ether (AME) and tentoxin (TEN) are Alternaria mycotoxins produced by the most common post-harvest pathogens of fruits. The production of these metabolites depends on several environmental factors, mainly temperature, water activity, pH and the technological treatments that have been applied to the product. In this study, the occurrence of AOH, AME and TEN was evaluated in strawberries samples stored at different temperatures ranges (at 22 ± 2 or 6 ± 2°C) and different periods (up to 1 month) simulating the current practice of consumer's storage conditions. Sample extraction was performed using a liquid-liquid extraction method prior to LC-MS/MS analysis. AOH was the most prevalent mycotoxins with a 42% at strawberries stored at (22 ± 2)°C and 37% stored at (6 ± 2)°C. The highest AOH levels were found in samples conserved at (22 ± 2)°C ranging between 26 and 752 ng g(-1). AME levels ranged between 11 and 137 ng g(-)(1), which were found mainly in stored samples at (6 ± 2)°C for more than 28 days. None sample presented levels of TEN in either of the studied conditions.

  18. Excito-Repellency of Citrus hystrix DC Leaf and Peel Essential Oils Against Aedes aegypti and Anopheles minimus (Diptera: Culicidae), Vectors of Human Pathogens.

    Science.gov (United States)

    Nararak, Jirod; Sathantriphop, Sunaiyana; Kongmee, Monthathip; Bangs, Michael J; Chareonviriyaphap, Theeraphap

    2017-01-01

    The essential oils of kaffir lime (Citrus hystrix DC.) at four different concentrations (0.5, 1.0, 2.5, and 5.0% v/v) were studied for their repellency, excitation, and knockdown properties against laboratory strains of Aedes aegypti (L.) and Anopheles minimus Theobald using an excito-repellency test system. Both contact and noncontact escape responses to leaf- and peel-derived kaffir lime oils were observed. Comparing unadjusted escape responses for An. minimus, leaf oil had strong combined irritant and repellent activity responses at 1-5% concentrations (90.0-96.4% escape) and the strongest spatial repellent activity at 1% and 2% (85.9% and 87.2% escape, respectively). The peel oil exhibited good excitation with repellency at concentrations of 2.5% (89.8% escape) and 5% (96.28% escape), while concentrations 1-5% showed more moderate repellent activity against An. minimus. For Ae. aegypti, 2.5% leaf oil produced the greatest response for both contact (56.1% escape) and noncontact (63.3% escape) trials, while 2.5% produced the strongest response among all concentrations of peel oil, with 46.5% escape. However, after adjusting the contact trial escape (a measure of combined excitation and repellency), the estimated escape due to contact alone was a much weaker response than spatial repellency for both species. Knockdown responses above 50% were only observed in Ae. aegypti exposed to 5% leaf oil. Kaffir lime oils were more active against An. minimus than Ae. aegypti mosquitoes. There were statistically significant differences between leaf (more active) and peel oils at each concentration against An. minimus in contact and noncontact trials, except at the highest (5%) concentration. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. 柑橘木虱两地理种群的内共生菌群落组成及传菌能力%The endosymbiotic microbiota of two geographical populations of the Asian citrus psyllid,Diaphorina citri,in China and its ability of pathogen transmission

    Institute of Scientific and Technical Information of China (English)

    马晓芳; 张学潮; 徐海君

    2012-01-01

    柑橘黄龙病(Huanglongbing,HLB)是经柑橘木虱Diaphorina citri传播的最主要柑橘病害之一,危害严重时能对柑橘产业造成毁灭性的破坏.为了鉴定福建和海南2个地理种群柑橘木虱的内共生菌群落组成,本研究对16SrRNA部分保守序列进行PCR扩增,并利用特异性引物对不同内共生菌进行了感染率检测;另外,还通过人工接虫的方法,探索柑橘木虱成虫在带黄龙病菌蕉柑Citrus reticulata cv.Tankan 上的获菌能力,以及带菌柑橘木虱成虫对黄岩蜜橘C.reticulata cv.Subcompress的传菌能力.研究发现,这2个地理种群的柑橘木虱含有相同的内共生菌组成,包括α-Proteobacteria,Wolbachia spp.,γ-Proteobacteria,mycetocyte symbionts,β-Proteobacteria,Oxalobacter 和β-Proteobacteria,Herbaspirillum,而且这2个地理种群柑橘木虱的4种内共生菌的携带率均在95%以上.柑橘木虱成虫在带菌蕉柑上饲菌28 d后,带菌率可达到82%,而带菌柑橘木虱成虫在黄岩蜜橘上传菌75 d后,可导致橘树整体带菌.本研究为柑橘木虱的进一步研究和防虫治病途径提供了一些理论依据.%Huanglongbing (HLB) is one of the most severe citrus diseases, which is usually transmitted by the Asian citrus psyllid ( Diaphorina citri), and causes great economic loss. To understand the endosyrnbiotic microbiota of the citrus psyllid from Hainan and Fujian provinces in China, the partial conserved region of 16S rRNA was amplified by PCR, and subsequently the infection rate of each endosymbiont from two geographical populations of the citrus psyllid was detected by PCR using specific primer pairs in this stduy. Moreover, we detected the acquisition efficiency of the pathogen by adult citrus psyllid reared on Citrus reticulata cv. Tank an infected with Candidatus Liberibacter as iatic us (CLas) , and the transmission efficiency to Citrus reticulata cv, Subcompress via CLas-positive psyllids. The results demonstrated that the two

  20. Effect of citrus pulp on the viability of the probiotic Saccharomyces cerevisiae bouldarii (Levucell) and subsequent effects in presence of pathogens

    Science.gov (United States)

    The probiotic Saccharomyces cerevisiae subtype boulardii (i.e., Levucell) is commonly provided to weaned and nursing sows to promote intestinal health through limiting the colonization of pathogens. Recent research from our group identified that supplementation of this probiotic to feed containing t...

  1. Citrus huanglongbing: a newly relevant disease presents unprecedented challenges.

    Science.gov (United States)

    Wang, Nian; Trivedi, Pankaj

    2013-07-01

    Citrus huanglongbing (HLB) is one of the oldest citrus diseases and has been known for over a century. HLB is caused by 'Candidatus Liberibacter' spp. that are phloem-limited, fastidious α-proteobacteria and infect hosts in different Kingdoms (i.e., Animalia and Plantae). When compared with well-characterized, cultivatable plant-pathogenic Gram-negative bacteria, the interactions of uncultured insect-vectored plant-pathogenic bacteria, including 'Ca. Liberibacter' spp., with their hosts remain poorly understood. 'Ca. Liberibacter' spp. have been known to cause HLB, which has been rapidly spreading worldwide, resulting in dramatic economic losses. HLB presents an unprecedented challenge to citrus production. In this review, we focus on the most recent research on citrus, 'Candidatus Liberibacter asiaticus', and psyllid interactions, specifically considering the following topics: evolutionary relationships among 'Ca. Liberibacter' spp., genetic diversity, host range, genome analysis, transmission, virulence mechanisms, and the ecological importance of HLB. Currently, no efficient management strategy is available to control HLB, although some promising progress has been made. Further studies are needed to understand citrus, 'Ca. L. asiaticus', and psyllid interactions to design innovative management strategies. Although HLB has been problematic for over a century, we can only win the battle against HLB with a coordinated and deliberate effort by the citrus industry, citrus growers, researchers, legislatures, and governments.

  2. Citrus Waste Biomass Program

    Energy Technology Data Exchange (ETDEWEB)

    Karel Grohman; Scott Stevenson

    2007-01-30

    Renewable Spirits is developing an innovative pilot plant bio-refinery to establish the commercial viability of ehtanol production utilizing a processing waste from citrus juice production. A novel process based on enzymatic hydrolysis of citrus processing waste and fermentation of resulting sugars to ethanol by yeasts was successfully developed in collaboration with a CRADA partner, USDA/ARS Citrus and Subtropical Products Laboratory. The process was also successfully scaled up from laboratory scale to 10,000 gal fermentor level.

  3. Biological characteristics of the pathogen of citrus black spot%柑橘黑斑病菌生物学特性研究

    Institute of Scientific and Technical Information of China (English)

    卢松茂; 罗金水; 张汉荣; 余智城; 林智明; 林秀香

    2012-01-01

    本文测定了不同培养基、温度、pH、光照条件对柑橘黑斑病菌柑橘叶点霉(Phyllosticta citricarpa)菌丝生长和孢子萌发的影响,以明确其生物学特性.结果表明,该菌最适生长的培养基为燕麦片琼脂培养基(OA);菌丝最适生长温度为25~30℃,最适pH为5~7;在12h光暗交替条件下生长最好,全黑暗条件下生长最慢.分生孢子萌发最适温度为25℃,最适pH为6,以在0.2%葡萄糖溶液中的萌发率最高.菌丝和分生孢子在55℃水浴处理10 min均失活.%The effects of different media, temperatures, pH and lights on mycelial growth and conidial germination were tested to understand the biological characteristics of Phyllosticta citricarpa (McAlp.) Van der Aa causing the citrus black spot. The results showed that the optimum medium for mycelial growth was oatmeal agar (OA). For mycelial growth, the optimum temperature was 25-30℃ , and the optimum pH was 5-7. It grew the fastest under alternate light and darkness every 12 hours, but the slowest in darkness. The optimum temperature for conidial germination was 25 °C , and the optimum pH was 6. If the conidia grew in 0.2% glucose solutions, the percentage of conidial germination was the highest. The lethal temperature for the conidium and mycelium was 55℃, lasting for 10 minutes.

  4. Molecular diversity and evolutionary processes of Alternaria solani in Brazil inferred using genealogical and coalescent approaches.

    Science.gov (United States)

    Lourenço, Valdir; Moya, Andrés; González-Candelas, Fernando; Carbone, Ignazio; Maffia, Luiz A; Mizubuti, Eduardo S G

    2009-06-01

    Alternaria spp. form a heterogeneous group of saprophytic and plant-pathogenic fungi widespread in temperate and tropical regions. However, the relationship between evolutionary processes and genetic diversity with epidemics is unknown for several plant-pathogenic Alternaria spp. The interaction of Alternaria solani populations with potato and tomato plants is an interesting case study for addressing questions related to molecular evolution of an asexual fungus. Gene genealogies based on the coalescent process were used to infer evolutionary processes that shape the A. solani population. Sequences of the rDNA internal transcribed spacer (ITS) region and the genes which encode the allergenic protein alt a 1 (Alt a 1) and glyceraldehyde-3-phosphate dehydrogenase (Gpd) were used to estimate haplotype and nucleotide diversity as well as for the coalescent analyses. The highest number of parsimony informative sites (n = 14), nucleotide diversity (0.007), and the average number of nucleotide differences (3.20) were obtained for Alt a 1. Although the highest number of haplotypes (n = 7) was generated for ITS, haplotype diversity was the lowest (0.148) for this region. Recombination was not detected. Subdivision was inferred from populations associated with hosts but there was no evidence of geographic subdivision, and gene flow is occurring among subpopulations. In the analysis of the Alt a 1, balancing selection and population expansion or purifying selection could have occurred in A. solani subpopulations associated with potato and tomato plants, respectively. There is strong evidence that the subpopulation of A. solani that causes early blight in potato is genetically distinct from the subpopulation that causes early blight in tomato. The population of A. solani is clonal, and gene flow and mutation are the main evolutionary processes shaping its genetic structure.

  5. Mutation breeding in sunflower for resistance to alternaria leaf spot

    OpenAIRE

    de Marcelo Oliveira F.; Tulmann Augusto Neto; Regina Leite M.V.B.C.; Vania Castiglioni B.R.; Arias C.A.A.

    2004-01-01

    Genetic variability for resistance to Alternarla leaf spot disease (Alternaria helianthi) can be induced by radiation or chemical mutagens. The objectives of this study were to create genetic variability in cultivated sunflower and to select lines resistant to Alternaria leaf spot. In the first experiment, sunflower seeds of the genotype HA BR 104 were irradiated with 150 and 165 Gy of gamma rays. Seeds were sown in the field at the Embrapa Soybean experimental station, in Londrina, PR, Brazi...

  6. Studies on the cost-effective management of Alternaria blight of rapeseed-mustard (Brassica spp.

    Directory of Open Access Journals (Sweden)

    M.M. Khan

    2007-08-01

    Full Text Available Three systemic fungicides: Topsin-M (Thiophanate methyl, 70%WP, Ridomil MZ (Mancozeb, 64% + Metalaxyl, 8%WP, and Bavistin (Carbendazim, 50%WP alone and in combination with four non-systemic fungicides Captaf (Captan, 50%WP, Indofil M-45 (Mancozeb, 75%WP, Indofil Z-78 (Zineb, 75%WP, and Thiram (Thiram, 75%WP were evaluated both in vitro and in vivo for their effectiveness to manage Alternaria blight of rapeseedmustard caused by Alternaria brassicae. A pure culture of the pathogenic fungus was applied in the field at 2 g colonized sorghum seeds kg-1 soil. All the fungicides were evaluated for their efficacy at various concentrations, 50, 100, 150, 200 and 500 ppm, and were sprayed in the field at 0.2% a.i. l-1. All fungicides significantly reduced the severity of the disease but Ridomil MZ was most effective. Topsin-M at a concentration of 500 ppm was the most effective in reducing radial growth of the pathogenic fungi (74.2%. Ridomil MZ reduced disease severity by 32% and was followed in effectiveness by the combination Bavistin+Captaf (26.5%. Maximum yield was obtained in plots sprayed with Bavistin+Captaf (1198 kg ha-1 followed by Bavistin+Indofil Z-78 (1172 kg ha-1. It was worth noting that the highest net profit as well as the highest cost-benefit ratio was obtained with Bavistin+Indofil Z-78 (1:3.2, followed by Bavistin+Captaf (1:1.3.

  7. Overexpression of a Modified Plant Thionin Enhances Disease Resistance to Citrus Canker and Huanglongbing (HLB).

    Science.gov (United States)

    Hao, Guixia; Stover, Ed; Gupta, Goutam

    2016-01-01

    Huanglongbing (HLB or citrus greening disease) caused by Candidatus Liberibacter asiaticus (Las) is a great threat to the US citrus industry. There are no proven strategies to eliminate HLB disease and no cultivar has been identified with strong HLB resistance. Citrus canker is also an economically important disease associated with a bacterial pathogen (Xanthomonas citri). In this study, we characterized endogenous citrus thionins and investigated their expression in different citrus tissues. Since no HLB-resistant citrus cultivars have been identified, we attempted to develop citrus resistant to both HLB and citrus canker through overexpression of a modified plant thionin. To improve effectiveness for disease resistance, we modified and synthesized the sequence encoding a plant thionin and cloned into the binary vector pBinPlus/ARS. The construct was then introduced into Agrobacterium strain EHA105 for citrus transformation. Transgenic Carrizo plants expressing the modified plant thionin were generated by Agrobacterium-mediated transformation. Successful transformation and transgene gene expression was confirmed by molecular analysis. Transgenic Carrizo plants expressing the modified thionin gene were challenged with X. citri 3213 at a range of concentrations, and a significant reduction in canker symptoms and a decrease in bacterial growth were demonstrated compared to nontransgenic plants. Furthermore, the transgenic citrus plants were challenged with HLB via graft inoculation. Our results showed significant Las titer reduction in roots of transgenic Carrizo compared with control plants and reduced scion Las titer 12 months after graft inoculation. These data provide promise for engineering citrus disease resistance against HLB and canker.

  8. 黄龙病诱导下椪柑SSH文库的构建与分析%Construction and analysis of subtractive cDNA library from ponkan (Citrus reticulate ) leaves following infection with Honglongbin pathogen

    Institute of Scientific and Technical Information of China (English)

    钟云; 姜波; 易干军; 曾继吾; 王辉; 蒋侬辉; 周碧容

    2012-01-01

    A suppression subtractive hybridization library was successfully constructed using eDNA synthesized from RNA extracted from leaves of ponkan (Citrus reticulate Blanco) infected with Huang- longbing bacteria as tester and uninfected as driver. One hundred positive clones were randomly select- ed and sequenced, and 71 ESTs were obtained. A search against NCBI GenBank ,after removing the duplications and low quality sequences, revealed that 41 ESTs shared considerable homology with known genes and that 10 ESTs did not have matches. Functional annotation of the genes showed that they were related to metabolic pathways and physiological and biochemical processes such as stress- tolerance, transportation, energy metabolism, photosynthesis, proteometabolism, signaling, anti-oxi- dation. It was noteworthy that the lectin protein precursor gene that was commonly induced by pathogen was also found in the HLB bacteria-infected Ponkan leaf cDNA library. Q-PCR results showed that two analyzed HLB pathogen induced genes were indeed activated. These indicated that an active anti-infection reaction was initiated in Ponkan leaves during the early stage of HLB bacteria in- fection.%以实生苗和平椪柑(Citrus reticulate Blanco)为材料,采用抑制性差减杂交技术,分别以感染黄龙病与未感染黄龙病的椪柑叶片为检测方(tester)和驱动方(driver),成功构建了黄龙病诱导的差减cDNA文库。挑选了100个阳性克隆并成功测序得到71条EST,经NCBI基因库同源性比对。有41条非冗余高质量EST序列找到了同源序列,另有10条非冗余未搜索到同源序列。同源序列的基因涉及抗逆防御、运输、能量代谢、光合作用、蛋白代谢、信号转导、抗氧化等代谢途径和生理生化过程。值得注意的是文库中有由病原引起的韧皮部相关的凝集素蛋白的前体积累。挑选了2条进行Q—PCR定量分析,结果表明感病1周表达量增强不大,2

  9. Comparative evaluation of long-term storage techniques on viability and virulence of Alternaria solani

    Directory of Open Access Journals (Sweden)

    M.C. Ravikumar

    2016-07-01

    Full Text Available The study was conducted to test the viability and pathogenicity of different forms of Alternaria solani inoculum stored at different conditions and time intervals for a period of 16 months. The aim was to confirm the survival period of pathogen in soil and to determine the simplest method to maintain inoculum in laboratory for further studies. The cultures stored at 5 °C for 2, 4, 8 and 16 months were pathogenic, while cultures stored at room temperature turned non-pathogenic after 4 months. All 6 successive sub-cultures retained viability and virulence. All the target-spots stored at 5 °C were viable after all time intervals as tested by culturing and subsequent spray of harvested mycelial suspension, but at the room temperature (RT, 16 months old inoculum lost viability and virulence. The powdered tissue samples of target-spots stored at 5 °C were found pathogenic by spray method after all the intervals of the time but, at RT 16 month old sample lost virulence. In inoculation by soil splashing, powdered tissue stored in paper bag at 5 °C retained pathogenicity till 8 months, while at RT, the inoculum stored in paper bags and the inoculum mixed in soil lost pathogenicity after 4 months.

  10. Cercosporoid diseases of Citrus.

    Science.gov (United States)

    Huang, Feng; Groenewald, J Z; Zhu, Li; Crous, P W; Li, Hongye

    2015-01-01

    Citrus leaves and fruits exhibiting disease symptoms ranging from greasy spot, yellow spot, small or large brown spot, black dot, and brown dot were sampled from Fujian, Guangdong, Guizhou, Hunan, Jiangxi, Yunnan, Zhejiang provinces and the Guangxi Zhuang Autonomous Region in China. In total 82 isolates representing various cercosporoid genera were isolated from these disease symptoms, which were supplemented with eight Citrus cercosporoid isolates collected from other countries. Based on a morphological and phylogenetic study using sequence data from the nuclear ribosomal DNA's ITS1-5.8S-ITS2 regions (ITS), and partial actin (act), β-tubulin (tub2), 28S nuclear ribosomal RNA (28S rDNA) and translation elongation factor 1-α (tef1) genes, these strains were placed in the following genera: Cercospora, Pallidocercospora, Passalora, Pseudocercospora, Verrucisporota and Zasmidium. All isolates tended to be sterile, except the Zasmidium isolates associated with citrus greasy spot-like symptoms, which subsequently were compared with phylogenetically similar isolates occurring on Citrus and other hosts elsewhere. From these results four Zasmidium species were recognized on Citrus, namely Z. indonesianum on Citrus in Indonesia, Z. fructicola and Z. fructigenum on Citrus in China and Z. citri-griseum, which appears to have a wide host range including Acacia, Citrus, Eucalyptus and Musa, as well as a global distribution.

  11. Certification Programs for Citrus

    Science.gov (United States)

    Citrus certification programs designed to ensure that healthy plants of the highest genetic potential are being planted in the field are the basic building block of an integrated pest management program. Certification programs began for citrus began with the discovery that the diseases were graft t...

  12. Molecular Detection of Spiroplasma Citri Associated with Stubborn Disease in Citrus Orchards in Syria

    Science.gov (United States)

    Spiroplasma citri, a phloem-limited pathogen, causes citrus stubborn disease (CSD) and can be transmitted from plant to plant by several species of phloem-feeding leafhoppers. CSD is an important disorder in certain warm and arid citrus-growing areas, and its agent has been recorded from several Med...

  13. An Inexpensive and Safe Experiment to Demonstrate Koch's Postulates Using Citrus Fruit

    Science.gov (United States)

    Jakobi, Steven

    2010-01-01

    Citrus fruit (oranges, tangerines, grapefruit or lemons) purchased in a grocery store can be experimentally infected with readily-available sources of "Penicillium digitatum" to demonstrate the four basic steps of Koch's postulates, also known as proof of pathogenicity. The mould is isolated from naturally-infected citrus fruit into pure culture…

  14. Abundance of citrus leafminer larvae on citrus and citrus-related germplasm

    Science.gov (United States)

    The citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a key pest in most citrus growing regions worldwide. Adult citrus leafminers oviposit primarily on young elongating flush of citrus as well as other Rutaceae and some ornamental plants. Larvae feed on the epiderm...

  15. Trichoderma harzianum as a biocontrol agent against Alternaria alternata on tobacco

    Directory of Open Access Journals (Sweden)

    Jugoslav Ziberoski

    2012-06-01

    Full Text Available Trichoderma fungi are the most popular agents used in a biological control. Therefore, our aim was to determine an impact of Trichoderma harzianum on the fungus Alternaria alternata - a causing agent of the brown spot disease on tobacco. In vitro analyses were made in several variants of double culture, in order to study the effect of difusible and volatile metabolites. There was strong reducing effect on the development of A.alternata with various mechanisms of antagonistic influence. The volatile metabolites have also shown reducing effect. Some abnormalities were observed in the pathogen's morphology both in difusible and volatile metabolites. The strong reducing effect of T.harzianum towards A. alternata can be applied in biological control of this pathogen.

  16. Biochemical evaluation of resistance responses of potato to different isolates of Alternaria solani.

    Science.gov (United States)

    Shahbazi, Hadis; Aminian, Heshmatollah; Sahebani, Navazollah; Halterman, Dennis A

    2010-05-01

    The resistance phenotypes of nine potato cultivars to five isolates of Alternaria solani, causal agent of early blight, were studied after inoculation and growth under greenhouse conditions. We identified potato cultivars with both susceptible and resistant phenotypes as well as A. solani isolates with varying degrees of aggressiveness. Two potato cultivars and two pathogen isolates were selected for biochemical analysis of phenol production and peroxidase activity after inoculation. Phenol compounds were evaluated 2, 4, 6, and 8 days after inoculation, while peroxidase activities were monitored daily for 10 days. Native polyacrylamide electrophoresis was used to identify one protein with peroxidase activity in extracts taken 6 days after inoculation. Significantly higher peroxidase activity as well as total phenol content in potato was correlated with resistance in the Iranian potato cultivar Diamond. Variability of responses within the same cultivar to different isolates of A. solani suggests genotypic diversity between isolates that results in phenotypic diversity for pathogen aggressiveness.

  17. Leaf proteome profiling of transgenic mint infected with Alternaria alternata.

    Science.gov (United States)

    Sinha, Ragini; Bhattacharyya, Dipto; Majumdar, Aparupa Bose; Datta, Riddhi; Hazra, Saptarshi; Chattopadhyay, Sharmila

    2013-11-20

    The genus Mentha has been widely used in food, flavor, culinary, cosmetic and pharmaceutical industries. Substantial damage to this crop happened regularly due to environmental stresses like metal toxicity and pathogen attack. Here, an approach has been taken to raise transgenic mint over-expressing γ-glutamyl-cysteine synthetase (γ-ECS), the rate-limiting enzyme of GSH biosynthesis, resulted enhanced GSH content and its in planta expression confers significant tolerance towards abiotic/biotic stresses viz. metal toxicity - Cd, Zn as well as against infection of Alternaria alternata and Rhizoctonia solani. A differential proteomic analysis through 2-DE and MALDI TOF-TOF MSMS was performed to focus on the altered abundance of functionally important protein species in control and infected transgenic mint. Results showed a significant variation in the protein profile of the infected transgenic plant as compared to the wild/control transgenic counterpart. In addition to protein species related to stress and defense, redox regulation, transcription factors and energy & metabolism, protein species related to signaling and gene regulation as well as cell division also showed differential accumulation in infected transgenic. Hence, proteomics can be used as a tool to decipher the mechanism of action of GSH in providing tolerance against a necrotrophic fungus, A. alternata in transgenic mint. The reported work describes a comparative proteomics of non-model unsequenced plants like Mentha. There is a comparative protein profile between transgenic and its wild counterparts under control and infected condition. The work has an impact in crop proteomics and also tries to explain the application of proteomic approach to decipher the mechanism by which a foreign metabolite mediates stress tolerance in plant under control and infected condition. This article is part of a Special Issue entitled: Translational Plant Proteomics. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Quantitative distribution of 'Candidatus Liberibacter asiaticus' in citrus plants with citrus huanglongbing.

    Science.gov (United States)

    Li, Wenbin; Levy, Laurene; Hartung, John S

    2009-02-01

    Citrus huanglongbing (HLB), or greening disease, is strongly associated with any of three nonculturable gram-negative bacteria belonging to 'Candidatus Liberibacter spp.' 'Ca. Liberibacter spp.' are transmitted by citrus psyllids to all commercial cultivars of citrus. The diseases can be lethal to citrus and have recently become widespread in both São Paulo, Brazil, and Florida, United States, the locations of the largest citrus industries in the world. Asiatic HLB, the form of the disease found in Florida, is associated with 'Ca. Liberibacter asiaticus' and is the subject of this report. The nonculturable nature of the pathogen has hampered research and little is known about the distribution of 'Ca. L. asiaticus' in infected trees. In this study, we have used a quantitative polymerase chain reaction assay to systematically quantify the distribution of 'Ca. L. asiaticus' genomes in tissues of six species of citrus either identified in the field during survey efforts in Florida or propagated in a greenhouse in Beltsville, MD. The populations of 'Ca. L. asiaticus' inferred from the distribution of 16S rDNA sequences specific for 'Ca. L. asiaticus' in leaf midribs, leaf blades, and bark samples varied by a factor of 1,000 among samples prepared from the six citrus species tested and by a factor of 100 between two sweet orange trees tested. In naturally infected trees, above-ground portions of the tree averaged 10(10) 'Ca. L. asiaticus' genomes per gram of tissue. Similar levels of 'Ca. L. asiaticus' genomes were observed in some but not all root samples from the same plants. In samples taken from greenhouse-inoculated trees, levels of 'Ca. L. asiaticus' genomes varied systematically from 10(4) genomes/g at the graft inoculation site to 10(10) genomes/g in some leaf petioles. Root samples from these trees also contained 'Ca. L. asiaticus' at 10(7) genomes/g. In symptomatic fruit tissues, 'Ca. L. asiaticus' genomes were also readily detected and quantified. The highest

  19. Examination of the responses of different genotypes of citrus to huanglongbing (citrus greening) under different conditions.

    Science.gov (United States)

    Folimonova, Svetlana Y; Robertson, Cecile J; Garnsey, Stephen M; Gowda, Siddarame; Dawson, William O

    2009-12-01

    ABSTRACT Citrus Huanglongbing (HLB) is one of the most devastating diseases of citrus worldwide. The causal agent of HLB in Florida is thought to be 'Candidatus Liberibacter asiaticus'. In this work, we examined the responses of 30 different genotypes of citrus to Florida isolates of 'Ca. L. asiaticus' under controlled conditions in the greenhouse or growth room. Although 'Ca. L. asiaticus' was able to multiply in all of the plants, a wide range of responses was observed among different hosts. Based on the symptoms developed and the ability of plants to continue growth, the different genotypes were grouped into four categories: sensitive, which exhibited severe chlorosis on leaves, greatly reduced growth, and eventual death; moderately tolerant, which exhibited some scattered distinct symptoms but little or no growth reduction and no plant death; tolerant, which exhibited very minimal symptoms; and genotypes, which exhibited variable reactions. Interestingly, although 'Ca. L. asiaticus' was unevenly distributed within each particular plant, comparison of titers of the bacterium in different citrus genotypes revealed that most accumulated similar levels of 'Ca. L. asiaticus', demonstrating that there is no strict correlation between bacterial titer and severity of disease. Incubation of infected plants in the growth room with continuous light greatly affected symptoms production by reducing the time before distinctive symptoms developed and significantly increasing severity of chlorosis of leaves of all citrus genotypes. These results provide additional evidence of the correlation between disruption of phloem translocation of carbohydrates during HLB infection and the appearance of chlorotic symptoms in leaves of infected trees. We also examined interaction between 'Ca. L. asiaticus' and Citrus tristeza virus, which usually occurs in trees that become infected with HLB, and found no synergistic effect of the two pathogens. We trust that observations reported here

  20. A polyphasic approach to the taxonomy of the Alternaria infectoria species-group

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Sørensen, Jens Laurids; Nielsen, Kristian Fog;

    2009-01-01

    morphologically identifiable as belonging to the A. infectoria species-group together with 12 strains belonging to closely related species: Alternaria malorum (syn. Cladosporium malorum), Chalastospora cetera (syn. Alternaria cetera) and Embellisia abundans. Morphological examination separated the 51 strains...

  1. 桂枝抑制柑橘采后两种病原菌活性物质研究%Antifungal Activity of Ramulus cinnamomi extracts against two key Citrus Postharvest Pathogens

    Institute of Scientific and Technical Information of China (English)

    万春鹏; 周梦娇; 刘洋; 陈金印

    2014-01-01

    In order to screen Chinese herbal medicine with potential antifungal activity from Chinese herb -al medicine extracts against two key Citrus postharvest pathogens ,namely Penicillium italicum and Penicillium digitatum.Solvent extract and silica gel chromatography were used to determine the antifungal materials from the active herb extracts .The results suggested that Ramulus cinnamomi,Cinnamomum cassia,Asarum sieboldii, Herba Moslae,Cortex Moutan and Artemisia apiacea had powerful inhibitive effects on the two pathogens and the inhibition zones were all over 20 mm.Moreover,the antifungal materials of Ramulus cinnamomi,Cinnamo-mum cassia and Asarum sieboldii all existed in the ethyl acetate fraction .Ramulus cinnamomi showed the best inhibitive effects on the two pathogens ,and the inhibitive zones were 34.57 mm and 31.56 mm,respectively. While the MIC were 3.125 mg/mL and 6.25 mg/mL,respectively;the MFC were 6.25 mg/mL and 12.5 mg/mL,respectively.The inhibition zones of the ethyl acetate fraction of Ramulus cinnamomi were 45.33 mm and 40.53 mm,respectively.Four subfractions (Fr.1-Fr.4) were obtained from the ethyl acetate fraction by the silica gel chromatography .Fr.1 showed the best antifungal activity and cinnamaldehyde was the main antifungal material in Fr.1 detected by HPLC .%从中草药提取物中筛选对引起柑橘采后主要病害的两株真菌---意大利青霉( Penicillium italicum)和指状青霉( Penicillium digitatum)有抑菌活性的中草药;采用溶剂萃取和硅胶柱色谱对具有较好抑菌活性的中草药提取物进一步分离纯化,确定其抑菌活性物质。结果表明:桂枝、桂皮、细辛、香薷、牡丹皮和青蒿6种提取物对这两株真菌均有较好的抑菌效果,抑菌圈直径均达20 mm以上。其中桂枝、桂皮和细辛的抗菌活性物质主要存在于乙酸乙酯部位,且桂枝的抑菌活性最强,对意大利青霉和指状青霉的抑菌圈直径分别为34.57 mm和31

  2. Effect of climate change on Alternaria leaf spot of rocket salad and black spot of basil under controlled environment.

    Science.gov (United States)

    Pugliese, M; Cogliati, E; Gullino, M L; Garibaldi, A

    2012-01-01

    Plant responses to elevated CO2 and temperature have been much studied in recent years, but effects of climate change on pathological responses are still largely unknown. The pathosystems rocket (Eruca vesicaria subsp. sativa)--Alternaria leaf spot (Alternaria japonica) and basil (Ocimum basilicum)--black spot (Colletotrichum gloeosporioides) were chosen as models to assess the potential impact of increased CO2 and temperature on disease incidence and severity under controlled environment. Potted plants were grown in phytotrons under 4 different simulated climatic conditions: (1) standard temperature (ranging from 18 degrees to 22 degrees C) and standard CO2 concentration (400 ppm); (2) standard temperature and elevated CO2 concentration (800 ppm); (3) elevated temperature (ranging from 22 degrees to 26 degrees C, 4 degrees C higher than standard) and standard CO2 concentration; (4) elevated temperature and CO2 concentration. Each plant was inoculated with a spore suspension containing 1 x 10(5) cfu/ml of the pathogen. Disease incidence and severity were assessed 14 days after inoculation. Increasing CO2 to 800 ppm showed a clear increment in the percentage of Alternaria leaf spot on rocket leaves compared to standard conditions. Basil plants grown at 800 ppm of CO2 showed increased black spot symptoms compared to 400 ppm. Disease incidence and severity were always influenced by the combination of rising CO2 and increased temperature, compared to standard conditions (400 ppm of CO2 - 22 degrees C). Considering the rising concentrations of CO2 and global temperature, we can assume that this could increase the severity of Alternaria japonica on rocket and Colletotrichum gloeosporioides on basil.

  3. Requisitos nutricionais para o fungo Alternaria alternata Nutritional requirements for the fungus Alternaria alternata

    Directory of Open Access Journals (Sweden)

    Celia Maria Maganhotto de S. Silva

    1999-03-01

    Full Text Available Uma linhagem de Alternaria alternata (ALT A foi cultivada em meio sintético com diferentes fontes de C, N e vitaminas. O crescimento micelial foi avaliado durante sete dias após a semeadura e a esporulação no décimo dia de incubação. O meio sintético básico suplementado com biotina, NH4Cl e os carboidratos maltose e glicose suportaram um bom crescimento micelial (em média 0,75 cm/dia. Galactose e arabinose induziram significativamente a produção de esporos (mL-1, da ordem de 5,0 x10³ e 4,1 x 10³, respectivamente. Nas diferentes fontes de vitamina e N não houve diferenças significativas quanto ao crescimento micelial e à esporulação.A strain of Alternaria alternata (ALT A was tested using different sources of C, N and vitamins in order to find a medium for its growth and sporulation. The mycelial growth was evaluated for seven days after sowing and the sporulation on the tenth day of incubation. Among various C, N and vitamins compounds tested, highest mycelial growth was achieved with maltose and glucose (C, NH4Cl (N and biotin, with an average ratio of 0.75 cm/day. Sporulation reached highest values with galactose and arabinose (5.0 x 10³ and 4.1 x 10³ conidia mL-1, respectively. Others vitamins and N compounds did not influence the growth and sporulation.

  4. Overexpression of a citrus NDR1 ortholog increases disease resistance in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Hua eLu

    2013-06-01

    Full Text Available Emerging devastating diseases, such as Huanglongbing (HLB and citrus canker, have caused tremendous losses to the citrus industry worldwide. Genetic engineering is a powerful approach that could allow us to increase citrus resistance against these diseases. The key to the success of this approach relies on a thorough understanding of defense mechanisms of citrus. Studies of Arabidopsis and other plants have provided a framework for us to better understand defense mechanisms of citrus. Salicylic acid (SA is a key signaling molecule involved in basal defense and resistance (R-gene mediated defense against broad-spectrum pathogens. The Arabidopsis gene NDR1 is a positive regulator of SA accumulation and is specifically required for signaling mediated by a subset of R genes upon recognition of their cognate pathogen effectors. Our bioinformatic analysis identified an ortholog of NDR1 from citrus, ctNDR1. Overexpression of ctNDR1 complemented susceptibility conferred by the Arabidopsis ndr1-1 mutant to Pseudomonas syringae strains and also led to enhanced resistance to an oomycete pathogen Hyaloperonospora arabidopsidis. Such heightened resistance is associated with increased SA production and expression of the defense marker gene PR1. In addition, we found that expression of PR1 and accumulation of SA were induced to modest levels in citrus infected with Candidatus Liberibacter asiaticus, the bacterial pathogen associated with HLB disease. Thus, our data suggest that ctNDR1 is a functional ortholog of Arabidopsis NDR1. Since Ca. L. asiaticus infection only activates modest levels of defense responses in citrus, we propose that genetically increasing SA/NDR1-mediated pathways could potentially lead to enhanced resistance against HLB, citrus canker, and other destructive diseases challenging global citrus production.

  5. Determination of Alternaria Brown Spot (Alternaria alternata f.sp. citri) Disease on Minneola Tangelo in Çukurova Region

    OpenAIRE

    ERKILIÇ, Ali; CANIHOŞ, Yeter; BİÇİCİ, Mehmet

    1998-01-01

    In this study, the incidence and severity of Alternaria brown spot disease (Alternaria alternata f.sp. citri) in the Çukurova region were determined. Thirty-five Minneola tangelo orchards, with a total area of 2497 da, in 24 different locations were surveyed for this purpose. Leaf infections in all orchards were observed in the spring flushing period. Disease severity was found to be 0-10 % in 10 orchards, 11-20 % in 10 orchards, 21-30 % in 7 orchards, 31-40 % in 5 orchards, 42.5 % in 1 orch...

  6. Citrus diseases with global ramifications including citrus canker and huanglongbing

    Science.gov (United States)

    Although there are a number of diseases that plague citrus production worldwide, two bacterial diseases are particularly problematic. Both are of Asian origin and currently cause severe economic damage: Asiatic citrus canker (ACC) and citrus huanglongbing (HLB). Although ACC has been found in the ...

  7. Guidelines for Selection of Tissues for Electron Microscopy Confirmation of Candidatus Liberibacter spp. in Huanglongbing-affected Citrus

    OpenAIRE

    Achor, Diann; Davis, Craig L.; Brlansky, Ronald H.; Folimonova, Svetlana Y.

    2014-01-01

    Polymerase chain reaction (PCR) with the pathogen-specific primers and electron microscopy are the two techniques of choice that have been used for detection and identification of Candidatus Liberibacter spp. in the Huanglongbing (HLB)-affected citrus. Due to the low population and uneven distribution of Liberibacter in the diseased citrus trees finding the bacteria with transmission electron microscopy has been a challenge. Work with samples from HLB-affected citrus during the past 5 years h...

  8. Modeling huanglongbing transmission within a citrus tree.

    Science.gov (United States)

    Chiyaka, Christinah; Singer, Burton H; Halbert, Susan E; Morris, J Glenn; van Bruggen, Ariena H C

    2012-07-24

    The citrus disease huanglongbing (HLB), associated with an uncultured bacterial pathogen, is threatening the citrus industry worldwide. A mathematical model of the transmission of HLB between its psyllid vector and citrus host has been developed to characterize the dynamics of the vector and disease development, focusing on the spread of the pathogen from flush to flush (a newly developing cluster of very young leaves on the expanding terminal end of a shoot) within a tree. This approach differs from that of prior models for vector-transmitted plant diseases where the entire plant is the unit of analysis. Dynamics of vector and host populations are simulated realistically as the flush population approaches complete infection. Model analysis indicates that vector activity is essential for initial infection but is not necessary for continued infection because infection can occur from flush to flush through internal movement in the tree. Flush production, within-tree spread, and latent period are the most important parameters influencing HLB development. The model shows that the effect of spraying of psyllids depends on time of initial spraying, frequency, and efficacy of the insecticides. Similarly, effects of removal of symptomatic flush depend on the frequency of removal and the time of initiation of this practice since the start of the epidemic. Within-tree resistance to spread, possibly affected by inherent or induced resistance, is a major factor affecting epidemic development, supporting the notion that alternate routes of transmission besides that by the vector can be important for epidemic development.

  9. Liquid Chromatographic Determination of Alternaria Toxins in Carrots

    NARCIS (Netherlands)

    Solfrizzo, M.; Girolamo, De A.; Vitti, C.; Bulk, van den R.W.

    2004-01-01

    A liquid chromatographic (LC) method was developed for the determination of Alternaria radicina and A. alternata toxins in carrots. Toxins were extracted from carrot with an acidified mixture of water¿methanol¿acetonitrile. The filtered extract was divided in 2 parts that were purified by

  10. Alternaria-aantasting van aardappelknollen : evaluatie 2004/2005

    NARCIS (Netherlands)

    Schepers, H.T.A.M.; Remijn, J.F.A.; Goorden, P.

    2005-01-01

    In de eerste maanden van 2005 werden diverse aardappeltelers geconfronteerd met veel Alternaria in de knollen. Door zowel DLV Plant, PPO-AGV als Cebeco Agrochemie zijn met name in het Zuid Westen monsters van aardappelen met problemen opgestuurd naar diverse laboratoria waaronder Plant Research Inte

  11. [Cellulase and xylanase activity of phytopathogenic and endophytic fungal strains of Alternaria alternata (Fr.) Keissler].

    Science.gov (United States)

    Kurchenko, I M; Sokolova, O V; Zhdanova, N M; Iarynchyn, A M; Iovenko, O M

    2008-01-01

    A comparative analysis of cellulase and xylanase activity of 25 fungal strains of phytopathogenic and endophytic Alternaria alternata had been realized for the first time using the qualitative reactions. The rate of their linear growth on the media with carboxymethylcellulose or xylane had been studied. The cellulase and xylanase activities clearly depended on the distinct strain. The absence of distinct dependence of cellulase and xylanase activities on the species and organs of host plants was demonstrated. The majority of investigated strains of A. alternata did not possess a cellulase activity or the latter was low, but as a whole the phytopathogenic strains were more active than endophytic ones. Xylanase activity was considerable for the fungal strains of all trophyc groups. It was shown that the level of xylanase activity cannot become a biochemical marker of the A. alternata isolate pathogenicity.

  12. Secondary metabolite profiling of Alternaria dauci, A. porri, A. solani, and A. tomatophila.

    Science.gov (United States)

    Andersen, Birgitte; Dongo, Anita; Pryor, Barry M

    2008-02-01

    Chemotaxonomy (secondary metabolite profiling) has been shown to be of great value in the classification and differentiation in Ascomycota. However, few studies have investigated the use of metabolite production for classification and identification purposes of plant pathogenic Alternaria species. The purpose of the present study was to describe the methodology behind metabolite profiling in chemotaxonomy using A. dauci, A. porri, A. solani, and A. tomatophila strains as examples of the group. The results confirmed that A. dauci, A. solani, and A. tomatophila are three distinct species each with their own specific metabolite profiles, and that A. solani and A. tomatophila both produce altersolanol A, altertoxin I, and macrosporin. By using automated chemical image analysis and other multivariate statistic analyses, three sets of species-specific metabolites could be selected, one each for A. dauci, A. solani, and A. tomatophila.

  13. PHARMACOLOGICAL IMPORTANCE OF CITRUS FRUITS

    Directory of Open Access Journals (Sweden)

    Amita Tomar *, Mridula Mall and Pragya Rai

    2013-01-01

    Full Text Available This paper reviews the pharmacological importance of citrus fruits. Citrus fruits are used for various pharmacological importance. According to literature the citrus fruit possess anti-cancer, antimicrobial, antioxidant, antiulcer, anti-inflammatory, and hypolipidemic and hepatoprotective properties.

  14. Strategic planning for the Florida citrus industry: addressing citrus greening disease

    National Research Council Canada - National Science Library

    2010-01-01

    "Citrus greening, a disease that reduces yield, compromises the flavor, color, and size of citrus fruit and eventually kills the citrus tree, is now present in all 34 Floridian citrus-producing counties...

  15. Pathotypes and Genetic Diversity of Chinese Collections of Elsinoë fawcettii Causing Citrus Scab

    Institute of Scientific and Technical Information of China (English)

    HOU Xin; HUANG Feng; ZHANG Tian-yuan; XU Jian-guo; Hyde D Kevin; LI Hong-ye

    2014-01-01

    Two scab diseases are currently recognized on citrus:citrus scab, caused by Elsinoë fawcettii, and sweet orange scab, caused by E. australis. Although these pathogens are economically important, there is no molecular data on these species in China. Here we use internal transcribed spacer sequence data to report on host-speciifcity and genetic relationships among 46 isolates collected from the main citrus varieties grown across China. All strains isolated were E. fawcettii. Based on pathogenicity testing on 9 different citrus species, isolates were divided into 11 pathotypes (SM, FBHR, SJCR, SPOJCR, SR, SOJG, SPOJC, SRGC, Lemon and two unnamed pathotypes). SM is a new pathotype, and two isolates did not ift into any of the known pathotypes of E. fawcettii. Inter-simple sequence repeat (ISSR-PCR) assays separated the E. fawcettii isolates into 10 subgroups;the groupings basically corresponded to the pathogenicity test.

  16. 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.

  17. Antioxidant activity of Citrus fruits.

    Science.gov (United States)

    Zou, Zhuo; Xi, Wanpeng; Hu, Yan; Nie, Chao; Zhou, Zhiqin

    2016-04-01

    Citrus is well-known for its nutrition and health-promotion values. This reputation is derived from the studies on the biological functions of phytochemicals in Citrus fruits and their derived products in the past decades. In recent years, the antioxidant activity of Citrus fruits and their roles in the prevention and treatment of various human chronic and degenerative diseases have attracted more and more attention. Citrus fruits are suggested to be a good source of dietary antioxidants. To have a better understanding of the mechanism underlying the antioxidant activity of Citrus fruits, we reviewed a study on the antioxidant activity of the phytochemicals in Citrus fruits, introduced methods for antioxidant activity evaluation, discussed the factors which influence the antioxidant activity of Citrus fruits, and summarized the underlying mechanism of action. Some suggestions for future study were also presented.

  18. Antifungal Constituents from Fruits of Ficus hirta Extracts Against Citrus Postharvest Pathogens%五指毛桃果抑制柑橘采后病原菌活性成分研究

    Institute of Scientific and Technical Information of China (English)

    夏磊; 陈楚英; 李琼厚; 坤吉瑞; 赖伟; 李涵韬; 万春鹏

    2016-01-01

    Numerous medicinal plants were selected for their antifungal activities against citrus postharvest pathogens including Penicillium italicum and Penicillium digitatum. The extracts from fruits of Ficus hirta showed promising antifungal activity. However, the antifungal constituents were not clear. In order to elucidate the antifungal constituents existing in fruits of Ficus hirta, the ethanol extracts of fruits of Ficus hirta were isolated to identify the active constituents. The bioassay method tested by cylinder­plate was used to guarantee the isolation of antifungal constituents. Macro resin column, Sephadex LH­20 column and ODS column were used to isolate three compounds. Their structures were determined as pinocembrin­7­O­β­D­glucoside (compound 1), naringenin­7­O­β­D­glucoside(compound 2) and eriodictyol­7­O­β­D­glucoside (compound 3) by NMR and MS spectroscopy. Compound 1, namely pinocembrin­7­O­β­D­glucoside, showed good antifungal activity, which was the major antifungal constituent existing in fruits of Ficus hirta.%前期通过筛选对柑橘采后病原菌——意大利青霉和指状青霉菌有抑菌作用的中草药,发现五指毛桃果乙醇提取物具有很好的抑菌活性。为进一步研究其抑菌活性成分,对五指毛桃果中的抑菌活性成分进行分离、纯化及结构鉴定。釆用生物活性追踪的方式,以牛津杯法测定提取物抑菌活性来指导下一步分离纯化。依次采用大孔树脂柱、Sephadex LH­20凝胶柱和 ODS 柱层析分离得到3个单体化合物,通过核磁共振谱(NMR)和质谱(MS)波谱数据分析,对3个化合物进行结构解析,经鉴定他们分别为乔松素­7­O­β­D­葡萄糖苷(1)、柚皮素­7­O­β­D­葡萄糖苷(2)和圣草酚­7­O­β­D­葡萄糖苷(3)。化合物1具有很好的抑菌活性,为五指毛桃果主要的抑菌活性成分。

  19. Detection of Alternaria fungal contamination in cereal grains by a polymerase chain reaction-based assay.

    Science.gov (United States)

    Zur, Gideon; Shimoni, Eyal; Hallerman, Eric; Kashi, Yechezkel

    2002-09-01

    Alternaria sp. are important fungal contaminants of grain products; they secrete four structural classes of compounds that are toxic or carcinogenic to plants and animals and cause considerable economic losses to growers and the food-processing industry. Alternaria toxins have been detected by high-performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay, and other techniques. Here, we report the development of a polymerase chain reaction (PCR)-based method for the detection of Alternaria DNA. PCR primers were designed to anneal to the ITS1 and ITS2 regions of the 5.8S rDNA gene of Alternaria alternata or Alternaria solani but not to other microbial or plant DNA. We compared the sensitivity of PCR in detecting Alternaria DNA, that of the HPLC method in detecting Alternaria alternariol and alternariol methyl ether toxins, and that of the morphological examination of mycelia and conidia in experimentally infested corn samples. The sensitivity of toxin detection for HPLC was above the level of contamination in a set of commercially obtained grain samples, resulting in negative scores for all samples, while the PCR-based method and mold growth plating followed by morphological identification of Alternaria gave parallel, positive results for 8 of 10 samples. The PCR assay required just 8 h, enabling the rapid and simultaneous testing of many samples at a low cost. PCR-based evidence for the presence of Alternaria DNA followed by positive assay results for Alternaria toxins would support the rejection of a shipment of grain.

  20. A unique nrdB gene can be used to improve the current HLB pathogen detection system

    Science.gov (United States)

    Citrus Huanglongbing (HLB), also referred to as yellow shoot disease and citrus greening disease, seriously threatens citrus production worldwide. Currently, the impact of HLB is grave, as there is no cure. A bacterium, “Candidatus Liberibacter asiaticus” (CLas), has been considered as the pathogen ...

  1. Huanglongbing: An overview of a complex pathosystem ravaging the world's citrus.

    Science.gov (United States)

    da Graça, John V; Douhan, Greg W; Halbert, Susan E; Keremane, Manjunath L; Lee, Richard F; Vidalakis, Georgios; Zhao, Hongwei

    2016-04-01

    Citrus huanglongbing (HLB) has become a major disease and limiting factor of production in citrus areas that have become infected. The destruction to the affected citrus industries has resulted in a tremendous increase to support research that in return has resulted in significant information on both applied and basic knowledge concerning this important disease to the global citrus industry. Recent research indicates the relationship between citrus and the causal agent of HLB is shaped by multiple elements, in which host defense responses may also play an important role. This review is intended to provide an overview of the importance of HLB to a wider audience of plant biologists. Recent advances on host-pathogen interactions, population genetics and vectoring of the causal agent are discussed. © 2015 Institute of Botany, Chinese Academy of Sciences.

  2. Huanglongbing:An overview of a complex pathosystem ravaging the world’s citrus

    Institute of Scientific and Technical Information of China (English)

    John V da Graa; Greg W Douhan; Susan E Halbert; Manjunath L Keremane; Richard F Lee; Georgios Vidalakis; Hongwei Zhao

    2016-01-01

    Citrus huanglongbing (HLB) has become a major disease and limiting factor of production in citrus areas that have become infected. The destruction to the affected citrus industries has resulted in a tremendous increase to support research that in return has resulted in significant information on both applied and basic knowledge concerning this important disease to the global citrus industry. Recent research indicates the relationship between citrus and the causal agent of HLB is shaped by multiple elements, in which host defense responses may also play an important role. This review is intended to provide an overview of the importance of HLB to a wider audience of plant biologists. Recent advances on host-pathogen interactions, population genetics and vectoring of the causal agent are discussed.

  3. Use of differents potato somaclons for evaluating the resistance to Alternaria solani Sorauer by artificial inoculation in field condition

    Directory of Open Access Journals (Sweden)

    Michel Leiva-Mora

    2001-04-01

    Full Text Available The use of plant pathogens, for the genetic improving programs is an important matter to guarantee its success. Utilization of phytopathogenic isolates from natural source, let us to employ rapid screening in some important genotypes. In this work it was used a mycelium homogenizated of Alternaria solani Sor (strain IBP-As-4, with a relative concentration of 1.7x105 ufc ml-1. The inoculum was applied by spraying to the somaclons (obtained by mutagenic and in vitro selection with culture filtrated of the fungus, also to the susceptible (Desireé and resistant (Solanum chacoense cultivars, respectively. The first symptoms appeared after seventh day of inoculation. The behavior between somaclons and testers in the final evaluation were different. Solanum chacoense was the most resistant genotype, the somaclons IBP-93 and IBP-38 were more susceptible than Desireé. The somaclons IBP-27 reached a similar affectation score respect to Solanum chacoense. The rest of the somaclons had an intermediate performance. It was proved the important of using of pathogenic strains of Alternaria solani Sor, for making selection where the natural inoculum source it is weak. Key words: genetic, improvement, selection, Solanum tuberosum L.

  4. Sesquiterpene emissions from Alternaria alternata and Fusarium oxysporum: Effects of age, nutrient availability, and co-cultivation.

    Science.gov (United States)

    Weikl, Fabian; Ghirardo, Andrea; Schnitzler, Jörg-Peter; Pritsch, Karin

    2016-02-26

    Alternaria alternata is one of the most studied fungi to date because of its impact on human life - from plant pathogenicity to allergenicity. However, its sesquiterpene emissions have not been systematically explored. Alternaria regularly co-occurs with Fusarium fungi, which are common plant pathogens, on withering plants. We analyzed the diversity and determined the absolute quantities of volatile organic compounds (VOCs) in the headspace above mycelial cultures of A. alternata and Fusarium oxysporum under different conditions (nutrient rich and poor, single cultures and co-cultivation) and at different mycelial ages. Using stir bar sorptive extraction and gas chromatography-mass spectrometry, we observed A. alternata to strongly emit sesquiterpenes, particularly during the early growth stages, while emissions from F. oxysporum consistently remained comparatively low. The emission profile characterizing A. alternata comprised over 20 sesquiterpenes with few effects from nutrient quality and age on the overall emission profile. Co-cultivation with F. oxysporum resulted in reduced amounts of VOCs emitted from A. alternata although its profile remained similar. Both fungi showed distinct emission profiles, rendering them suitable biomarkers for growth-detection of their phylotype in ambient air. The study highlights the importance of thorough and quantitative evaluations of fungal emissions of volatile infochemicals such as sesquiterpenes.

  5. Cercosporoid diseases of Citrus

    NARCIS (Netherlands)

    Huang, Feng; Groenewald, J.Z.; Zhu, Li; Crous, P.W.; Li, Hongye

    2015-01-01

    Citrus leaves and fruits exhibiting disease symptoms ranging from greasy spot, yellow spot, small or large brown spot, black dot, and brown dot were sampled from Fujian, Guangdong, Guizhou, Hunan, Jiangxi, Yunnan, Zhejiang provinces and the Guangxi Zhuang Autonomous Region in China. In total 82 isol

  6. Two new compounds from an endophytic fungus Alternaria solani.

    Science.gov (United States)

    Ai, Hong-Lian; Zhang, Li-Mei; Chen, Yan-Ping; Zi, Shu-Hui; Xiang, Hong; Zhao, Da-Ke; Shen, Yong

    2012-01-01

    Two new secondary metabolites, named 7-dehydroxyl-zinniol (1) and 20-hydroxyl-ergosta-4,6,8(14),22-tetraen-3-one (2), were isolated from the culture of Alternaria solani, an endophytic fungal strain residing in the roots of Aconitum transsectum. Their structures were elucidated on the basis of comprehensive spectroscopic analyses including IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR. Biological activity tests indicated that compound 1 showed moderate anti-HBV activity.

  7. Potential Nutritional Benefits of Current Citrus Consumption

    Directory of Open Access Journals (Sweden)

    Tami Turner

    2013-03-01

    Full Text Available Citrus contains nutrients and phytochemicals that may be beneficial for health. We collected citrus production and consumption data and estimated the amount of these compounds that are consumed. We then compared the amounts of citrus and citrus-derived compounds used in studies that suggest a health benefit to the amounts typically found in citrus. Data is scarce, but suggests that citrus consumption might improve indices of antioxidant status, and possibly cardiovascular health and insulin sensitivity.

  8. Citrus tissue culture employing vegetative explants.

    Science.gov (United States)

    Chaturvedi, H C; Singh, S K; Sharma, A K; Agnihotri, S

    2001-11-01

    culture of shoots of C grandis without loss of regeneration capacity during 31 years, observed so far, are some other significant results. Plants of C. aurantifolia and C. sinensis raised from shoot meristem and micrografting were grown in a nethouse and those from nodal stem segments in the field along with the in vitro-raised plants of rootstocks, namely, C. jambhiri, C. karna and C. limonia. All the plants showed normal healthy growth. Significantly enough, the meristem regenerated plants of C. aurantifolia attained the reproductive phase just in 1 year of transplantation to soil similar to those raised from nodal stem segments of mature trees, which also produced normal fruits in the subsequent year while growing under field conditions. Thus, a significant fundamental concept of a maturity factor, carried over through as small a shoot meristem as 200 microm in length to cloned plants has been demonstrated. The concept is of far-reaching significance in citrus industry besides production of pathogen-free orchards.

  9. Emerging Fusarium and Alternaria Mycotoxins: Occurrence, Toxicity and Toxicokinetics

    Directory of Open Access Journals (Sweden)

    Sophie Fraeyman

    2017-07-01

    Full Text Available Emerging Fusarium and Alternaria mycotoxins gain more and more interest due to their frequent contamination of food and feed, although in vivo toxicity and toxicokinetic data are limited. Whereas the Fusarium mycotoxins beauvericin, moniliformin and enniatins particularly contaminate grain and grain-based products, Alternaria mycotoxins are also detected in fruits, vegetables and wines. Although contamination levels are usually low (µg/kg range, higher contamination levels of enniatins and tenuazonic acid may occasionally occur. In vitro studies suggest genotoxic effects of enniatins A, A1 and B1, beauvericin, moniliformin, alternariol, alternariol monomethyl ether, altertoxins and stemphyltoxin-III. Furthermore, in vitro studies suggest immunomodulating effects of most emerging toxins and a reproductive health hazard of alternariol, beauvericin and enniatin B. More in vivo toxicity data on the individual and combined effects of these contaminants on reproductive and immune system in both humans and animals is needed to update the risk evaluation by the European Food Safety Authority. Taking into account new occurrence data for tenuazonic acid, the complete oral bioavailability, the low total body clearance in pigs and broiler chickens and the limited toxicity data, a health risk cannot be completely excluded. Besides, some less known Alternaria toxins, especially the genotoxic altertoxins and stemphyltoxin III, should be incorporated in risk evaluation as well.

  10. Emerging Fusarium and Alternaria Mycotoxins: Occurrence, Toxicity and Toxicokinetics.

    Science.gov (United States)

    Fraeyman, Sophie; Croubels, Siska; Devreese, Mathias; Antonissen, Gunther

    2017-07-18

    Emerging Fusarium and Alternaria mycotoxins gain more and more interest due to their frequent contamination of food and feed, although in vivo toxicity and toxicokinetic data are limited. Whereas the Fusarium mycotoxins beauvericin, moniliformin and enniatins particularly contaminate grain and grain-based products, Alternaria mycotoxins are also detected in fruits, vegetables and wines. Although contamination levels are usually low (µg/kg range), higher contamination levels of enniatins and tenuazonic acid may occasionally occur. In vitro studies suggest genotoxic effects of enniatins A, A1 and B1, beauvericin, moniliformin, alternariol, alternariol monomethyl ether, altertoxins and stemphyltoxin-III. Furthermore, in vitro studies suggest immunomodulating effects of most emerging toxins and a reproductive health hazard of alternariol, beauvericin and enniatin B. More in vivo toxicity data on the individual and combined effects of these contaminants on reproductive and immune system in both humans and animals is needed to update the risk evaluation by the European Food Safety Authority. Taking into account new occurrence data for tenuazonic acid, the complete oral bioavailability, the low total body clearance in pigs and broiler chickens and the limited toxicity data, a health risk cannot be completely excluded. Besides, some less known Alternaria toxins, especially the genotoxic altertoxins and stemphyltoxin III, should be incorporated in risk evaluation as well.

  11. AGGRESSIVENESS AND MORPHOLOGICAL VARIABILITY OF SMALL SPORE Alternaria SPECIES ISOLATED FROM ALGERIA

    Directory of Open Access Journals (Sweden)

    Nabahat Bessadat

    2014-05-01

    Full Text Available Natural epidemics of blight disease are strongly influenced by environmental conditions, even though several diseases appears every year in north western of Algeria which can cause complete loss of the crop when the infection is severe. The fungi which are frequently associated with leaf blight, stem blight and apical fruit rot of Solanaceae family are Alternaria arborescens, A. alternata and A. tenuissima. These fungi were identified on morphological characteristics. For that, eighty one small spore strains belonging to the A. alternata section were assessed for disease symptoms, percent disease incidence (PDI and area under the diseases progress curve (AUDPC on three different tomato cultivars. Among the tested fungal isolates, it revealed that PDI of the isolates were changed according to the cultivar and the highest blight disease incidence was found in A. tenuissima strain 164 (96% in Saint Pierre, 59% in Cherry tomato and 69% in Rio Grande, it was followed be A. alternata strain 156 (90% in Saint Pierre, 82% in cherry tomato and 46% in Rio Grande and A. arborescens strain 65 (49% in Saint Pierre, 85% in cherry tomato and 63,15% in Rio Grande. According to the aggressiveness component of the isolates, the classical behavior of the cultivars was confirmed, and Saint Pierre and Rio Grande cultivars were found susceptible with a slightly higher mean of AUDPC (413.72 and 390.48 respectively but Cherry tomato cultivar was found to be resistant with the lowest AUDPC mean 227.18 ± 166.10. Based upon results of present study, it was concluded that a complex of small spore Alternaria species and isolates found on Solanaceae lesions are not equally pathogenic but majority of A. tenuissima isolates are not the part of this complex.

  12. Overexpression of a modified plant thionin enhances disease resistance to citrus canker and Huanglongbing (HLB

    Directory of Open Access Journals (Sweden)

    Guixia Hao

    2016-07-01

    Full Text Available Huanglongbing (HLB or citrus greening disease caused by Candidatus Liberibacter asiaticus (Las is a great threat to the US citrus industry. There are no proven strategies to eliminate HLB disease and no cultivar has been identified with strong HLB resistance. Citrus canker is also an economically important disease associated with a bacterial pathogen (Xanthomonas citri. In this study, we characterized endogenous citrus thionins and investigated their expression in different citrus tissues. Since no HLB-resistant citrus cultivars have been identified, we attempted to develop citrus resistant to both HLB and citrus canker through overexpression of a modified plant thionin. To improve effectiveness for disease resistance, we modified and synthesized the sequence encoding a plant thionin and cloned into the binary vector pBinPlus/ARS. The construct was then introduced into Agrobacterium strain EHA105 for citrus transformation. Transgenic Carrizo plants expressing the modified plant thionin were generated by Agrobacterium-mediated transformation. Successful transformation and transgene gene expression was confirmed by molecular analysis. Transgenic Carrizo plants expressing the modified thionin gene were challenged with X. citri 3213 at a range of concentrations, and a significant reduction in canker symptoms and a decrease in bacterial growth were demonstrated compared to nontransgenic plants. Furthermore the transgenic citrus plants were challenged with HLB via graft inoculation. Our results showed significant Las titer reduction in roots of transgenic Carrizo compared with control plants and reduced scion Las titer twelve months after graft inoculation. These data provide promise for engineering citrus disease resistance against HLB and canker.

  13. Isolation and characterization of microsatellite markers from the phytopathogenic fungus Alternaria dauci.

    Science.gov (United States)

    Benichou, Soumaya; Dongo, Anita; Henni, Djamel Eddine; Peltier, Didier; Simoneau, Philippe

    2009-01-01

    Eleven polymorphic microsatellite markers were isolated from the necrotrophic phytopathogenic fungus Alternaria dauci based on enriched genomic libraries. In order to assess allelic variability, the microsatellite loci were analysed in a collection of 43 isolates. The number of detected alleles in 11 loci ranged from two to 24 (mean 10.4). Test of cross-species amplification and sequencing of the resulting amplicons showed that some of these microsatellites could be used in different species such as Alternaria solani, Alternaria bataticola and Alternaria zinniae. © 2008 The Authors. Journal compilation © 2008 Blackwell Publishing Ltd.

  14. Some new and noteworthy diseases of poplars in India. [Botryodiplodia sett-rot; Alternaria tip blight; Cladosporium leaf spot; Fusarium pink incrustation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.

    1983-09-01

    Four new diseases of poplars namely Botryodiplodia sett-rott, Alternaria tip blight, Cladosporium leaf spot and Fusarium pink incrustation are described in this paper. Botryodiplodia palmarum causes sett-rott of poplars both at pre-sprouting and post-sprouting stage. The pathogen also causes mortality of poplar plants in the field within 4-6 weeks after planting. Alternaria stage of Pleuspora infectoria has been found as the cause of blackening and dying of growing tips and young leaves of a Populus sp. and P. deltoides in nurseries. Cladosporium humile has been recorded as the cause of brown spot followed by crumpling and premature shedding of leaves in P. ciliata, P. nigra and P. alba. The cause of Fusarium incrustation disease on P. cilata has been identified as Fusarium sp. of Gibbosum group. Pathogenicity of Botryodiplodia palmarum and Alternaria stage of Pleospora infectoria was confirmed by artificial inoculations. Brief descriptions of Alternaria, Cladosporium and Fusarium are also given. The paper also gives a short account of some noteworthy diseases recorded on poplars namely Ganoderma root rot, foliage ruts and stem cankers. Ganoderma root-rot is found to reach alarming proportions in closely spaced poplar plantations. Melampsora ciliata, an indigenous rust, is found to attack mainly clones of P. deltoides, P. yunnanensis, P. trichocarpa, P. alba and some cultivars of P. x euramericana in nurseries. A brief account of three types of stem cankers i.e. cankers due to pink disease fungus, Corticium salmonicolor, sun-scaled cankers and cankers associated with slime flux on various clones of P. deltoides is also given.

  15. PCR detection of huanglongbing pathogen in different parts of citrus plants in the field and analysis of the cause of the disease%田间柑橘植株不同部位黄龙病菌的PCR检测及发病原因分析

    Institute of Scientific and Technical Information of China (English)

    鹿连明; 范国成; 胡秀荣; 张利平; 黄振东; 陈国庆

    2011-01-01

    [Objective]Understanding the distribution of pathogen in plants laid the foundation for further studies on its diffusion in plants, and clarifying the reason for disease occurrence could provide reference for effective control of the disease.[Method]Citrus huanglongbing in Taizhou, Zhejiang Province, was investigated, and the pathogen in different plants and different parts of the same plant, was detected by conventional and nested PCR.[Result]It showed that the pathogen was present in leaves with or without symptoms and in branches in one orchard, but not in surrounding plants.In the other orchards, the pathogen was present in leaves, branches, main trunk, rootstock, and also in surrounding plants with symptoms.[Conclusion]It indicated that the causes of the disease in the two plants were different.One might be infected by citrus psylla, while the other by grafting.%[目的]了解黄龙病菌在柑橘植株不同部位的分布,为深入研究病菌在植株体内的扩散情况莫定基础;明确病害的发生原因为有效防控该病害提供借鉴.[方法]调查浙江省台州市柑橘黄龙病(huanglongbing,HLB)的发生情况,通过常规和巢式PCR,检测了发病情形不同的两个果园内柑橘病株不同部位及不同植株中的黄龙病菌,并对其发病原因进行分析.[结果]发现一果园内病株的无症状叶片、有症状叶片和枝条中均含有黄龙病菌,而其周围植株不含病菌;另一果园内病株的有症状叶片、枝条、主干和砧木中均含有黄龙病菌,而其周围植株也含菌.[结论]分析认为这两种果园内柑橘植株发病原因不同,一种可能为通过携带黄龙病菌的柑橘木虱所感染,另一种可能为嫁接过程中通过带菌的接穗感染.

  16. Antimicrobial activity of wax and hexane extracts from Citrus spp. peels

    OpenAIRE

    Susana Johann; Vetúria Lopes de Oliveira; Pizzolatti,Moacir G.; Jan Schripsema; Raimundo Braz-Filho; Alexsandro Branco; Artur Smânia Jr

    2007-01-01

    Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from pe...

  17. 重楼提取物对柑桔3种病原真菌的抑制活性%Antifungal Activity of the Extract of The Rhizoma Paridis Against Three Pathogenic Fungi of Citrus

    Institute of Scientific and Technical Information of China (English)

    李敏敏; 胡军华; 眺廷山; 贺磊; 冉春; 李鸿筠; 刘浩强

    2011-01-01

    Extracts from Rhizoma Paridis were measured in laboratory for their activities against Alternaria citri, Phytophthora citrophthora and Colletorichwn gloeosporioid.es using growth rate methods. Four different solvents, benzene, anhydrous ether, ethyl acetate and ethanol were used in the preparation of the extracts. The results showed that all extracts had anti-fungal activities when used at the concentration of 50 mg · mL-1. The ethanol extract exhibited a 100% of growth inhibition to C. Gloeosporioidts with a EQ50 of 0. 697 1 mg · mL-1. Under microscopy, the fungal mycelium treated with the ethanol extract was found to be deformed, decolored and reduced in the number of septa An initial analysis of the ethanol extract indicated that the antifungal materials are saponins.%本试验采用菌丝生长速率法测定了重楼Paris polyphylla的苯、无水乙醚、乙酸乙酯、乙醇提取物对柑桔链格孢菌Alternaria citri、柑桔褐腐疫霉菌Ph ytophthora citrophthora、柑桔炭疽菌Colletotrichum gloeosporioides等3种病原菌的抑制活性.结果表明,在50 mg·mL-1浓度下各提取物均有抑制作用,其中重楼乙醇提取物对柑桔炭疽菌的抑制率达100%,EC50为0.697 1 mg·mL-1.显微观察发现,重楼乙醇提取物处理后的柑桔炭疽菌菌丝出现分隔减少、畸形等变化.对重楼乙醇提取物进行抑菌活性成分分离和鉴定,推测其主要抑菌成分为皂苷类物质.

  18. 柑橘黄龙病兼性厌氧型伴生细菌的分离及优势菌群分析%Isolation of facultative anaerobic and entophytic bacteria companioned Huanglongbing pathogen-infected citrus tissues and determination of dominant bacterial populations

    Institute of Scientific and Technical Information of China (English)

    李颜方; 殷幼平; 王玉玺; 李佳; 陈世伟; 王中康

    2011-01-01

    柑橘黄龙病是世界柑橘生产上最具毁灭性的病害,主要由难人工培养的韧皮杆菌所引起(Candidatus Liberibacter asiaticus)[1].近年的研究结果表明黄龙病发病组织内除了韧皮杆菌外,还可能有促进或抑制黄龙病菌生长的伴生性细菌[2,3].国内外已有不少关于植物内生细菌的研究报道[4],但关于柑橘内生细菌的报道较少.本研究旨在以多年生发病与健康柑橘植株的内生细菌为研究对象,采用定向分离方法培养兼性厌氧型内生细菌,利用基于16S rRNA的PCR-DGGE宏基因组学方法分析比较柑橘健株与病株内生菌群的差异,旨在发现与黄龙病伴生的功能性内生细菌.%To analyze the diversity of entophytic bacteria and find the companion microbe in Huanglongbing pathogen-infected and healthy citrus plant tissues, various parts of citrus tissues were collected from different locations of citrus planting areas. The facultative anaerobic and entophytic bacteria were isolated and identified based on bacterial morphology, physiology, biochemistry characteristics and PCR-DGGE analysis (denaturing gradient gel electrophoresis, analysis of the sequence of 16S rRNA V6-V8 fragment). By the directional isolation of the facultative anaerobic and entophytic bacteria and 16S rDNA amplification methods, total 12 genera of bacteria were identified from 19 cultivable bacterial populations. The dominant bacterial population were Bacillus sp. (IF: 21.03% ), Planococcus sp. (IF:20.69% ) and Pseudomonas sp. (IF: 17.44% ) in healthy citrus tissues, while Curtobacterium sp. (IF: 29.07% ), Bacillus sp. (IF: 23.12% ) , Microbacterium sp. (IF; 21.09% )in infected citrus plants. Based on the results of DGGE, 9 genera of cultured bacteria were identified. The dominant bacteria population was Serratia sp. (IF: 28% ), and Pantoea sp. (IF: 14% ) was second only to it. ' Candidatus Liberibacter asiaticus' was found only in tangerine pith of deformed orange fruit

  19. Localization of melanin in conidia of Alternaria alternata using phage display antibodies.

    Science.gov (United States)

    Carzaniga, Raffaella; Fiocco, Daniela; Bowyer, Paul; O'Connell, Richard J

    2002-03-01

    Melanins derived from 1,8-dihydroxynaphthalene (DHN) are important for the pathogenicity and survival of fungi causing disease in both plants and animals. However, precise information on their location within fungal cell walls is lacking. To obtain antibodies for the immunocytochemical localization of melanin, 83 phage antibodies binding to 1,8-DHN were selected from a naive semisynthetic single-chain Fv (scFv) phage display library. Sequence analysis of the heavy chain binding domains of 17 antibodies showed a high frequency of positively charged amino acids. One antibody, designated M1, was characterized in detail. M1 bound specifically to 1,8-DHN in competitive inhibition enzyme-linked immunosorbent assays, showing no cross-reaction with nine structurally related phenolic compounds. Epitope recognition required two hydroxyl groups in a 1,8 configuration. M1 also bound to naturally occurring melanin isolated from mycelia of Alternaria alternata, suggesting that epitopes remain accessible in polymerized melanin. Transmission electron microscopy-immunogold labeling, using M1 in the form of soluble scFv fragments, showed that melanin was located in the septa and outer (primary) walls of wild-type A. alternata conidia, but not those of an albino mutant, AKT88-1. The M1 antibody provides a new tool for detecting melanized pathogens in plant and animal tissues and for precisely mapping the distribution of the polymer within spores, appressoria, and hyphae.

  20. Development of multiplex polymerase chain reaction assay for simultaneous detection of clostero-, badna- and mandari-viruses along with huanglongbing bacterium in citrus trees.

    Science.gov (United States)

    Meena, Ram Prasnna; Baranwal, V K

    2016-09-01

    Citrus trees harbor a large number of viral and bacterial pathogens. Citrus yellow vein clearing virus (CYVCV), Indian citrus ringspot virus (ICRSV), Citrus yellow mosaic virus (CYMV), Citrus tristeza virus (CTV) and a bacterium, Candidatus Liberibacter asiaticus (CLa) associated with huanglongbing (HLB) disease, the most prevalent pathogens in citrus orchards of different regions in India and are responsible for debilitating citriculture. For detection of these viral and bacterial pathogens a quick, sensitive and cost effective detection method is required. With this objective a multiplex polymerase chain reaction (mPCR) assay was developed for simultaneous detection of four viruses and a bacterium in citrus. Several sets of primers were designed for each virus based on the retrieved reference sequences from the GenBank. A primer pair published previously was used for greening bacterium. Each pair of primers was evaluated for their sensitivity and differentiation by simplex and mPCR. The constant amplified products were identified on the basis of molecular size in mPCR and were compared with standard PCR. The amplicons were cloned and results were confirmed with sequencing analysis. The mPCR assay was validated using naturally infected field samples for one or more citrus viruses and the huanglongbing bacterium. The mPCR assay developed here will aid in the production of virus free planting materials and rapid indexing for certification of citrus budwood programme. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Metabolic Interplay between the Asian Citrus Psyllid and Its Profftella Symbiont: An Achilles' Heel of the Citrus Greening Insect Vector.

    Directory of Open Access Journals (Sweden)

    John S Ramsey

    Full Text Available 'Candidatus Liberibacter asiaticus' (CLas, the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including 'Candidatus Profftella armatura', are likely to impact transmission of CLas. We used quantitative mass spectrometry to compare the proteomes of CLas(+ and CLas(- populations of D. citri, and found that proteins involved in polyketide biosynthesis by the endosymbiont Profftella were up-regulated in CLas(+ insects. Mass spectrometry analysis of the Profftella polyketide diaphorin in D. citri metabolite extracts revealed the presence of a novel diaphorin-related polyketide and the ratio of these two polyketides was changed in CLas(+ insects. Insect proteins differentially expressed between CLas(+ and CLas(- D. citri included defense and immunity proteins, proteins involved in energy storage and utilization, and proteins involved in endocytosis, cellular adhesion, and cytoskeletal remodeling which are associated with microbial invasion of host cells. Insight into the metabolic interdependence between the insect vector, its endosymbionts, and the citrus greening pathogen reveals novel opportunities for control of this disease, which is currently having a devastating impact on citrus production worldwide.

  2. Characterization of Alternaria strains from Argentinean blueberry, tomato, walnut and wheat

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Nielsen, Kristian Fog; Fernández Pinto, Virginia

    2015-01-01

    Alternaria species have the ability to produce a variety of secondary metabolite, which plays important roles in food safety. Argentina is the second largest exporter of fresh and processed food products to Europe, however, fewstudies on Alternaria mycotoxins and other bioactive secondary...

  3. Zinc treatment increases the titre of 'Candidatus Liberibacter asiaticus' in huanglongbing-affected citrus plants while affecting the bacterial microbiomes.

    Science.gov (United States)

    Zhang, M Q; Guo, Y; Powell, C A; Doud, M S; Yang, C Y; Zhou, H; Duan, Y P

    2016-06-01

    Huanglongbing (HLB)-affected citrus often display zinc deficiency symptoms. In this study, supplemental zinc was applied to citrus to determine its effect on Candidatus Liberibacter asiaticus (Las) titre, HLB symptoms, and leaf microbiome. HLB-affected citrus were treated with various amounts of zinc. The treatments promoted Las growth and affected microbiomes in citrus leaves. Phylochip(™) -based results indicated that 5475 of over 50 000 known Operational Taxonomic Units (OTUs) in 52 phyla were detected in the midribs of HLB-affected citrus, of which Proteobacteria was the most abundant, followed by Firmicutes and Actinobacteria. In comparison, the microbiomes of zinc-treated diseased plants had overall more OTUs with higher amounts of Proteobacteria, but decreased percentages of Firmicutes and Actinobacteria. In addition, more OTUs of siderophore-producing bacteria were present. Only zinc-sensitive Staphylococcaceae had higher OTU's in the diseased plants without zinc treatments. Although HLB-affected citrus appear zinc deficient, zinc amendments increased the pathogen levels and shifted the microbiome. HLB is currently the most devastating disease of citrus worldwide. Zinc is often applied to HLB-affected citrus due to zinc deficiency symptoms. This study provided new insights into the potential effects of zinc on HLB and the microbial ecology of citrus. © 2016 The Society for Applied Microbiology.

  4. 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.

  5. Novel chemotaxonomic markers of the Alternaria infectoria species-group

    DEFF Research Database (Denmark)

    Christensen, K.B.; Van Klink, J.W.; Weavers, R.T.;

    2005-01-01

    Two new structurally related metabolites, novae-zelandin A (1) and novae-zelandin B (2), as well as the novel metabolite 4Z-infectopyrone (3) were purified from extracts of filamentous fungi belonging to the Alternaria infectoria species-group. The structures were elucidated by a combination of 1...... and 2D NMR spectroscopic data and MS data. 1-3 are important chemotaxonomic markers of the A. infectoria species-group and exhibit structures similar to those of known biologically active compounds, suggesting that they could be potential phytotoxins....

  6. Two new zinniol-related phytotoxins from Alternaria solani.

    Science.gov (United States)

    Moreno-Escobar, Jorge; Puc-Carrillo, Alejandra; Cáceres-Farfán, Mirbella; Peña-Rodríguez, Luis M; Gamboa-Angulo, M Marcela

    2005-09-01

    Bioassay-guided purification of the organic crude extract of Alternaria solani resulted in the isolation of three metabolites responsible for causing necrosis on potato leaves. These phytotoxins were identified as 2-(2",3"-dimethyl-but-1-enyl)-zinniol (1), 8-zinniol methyl ether (2). and 8-zinniol methyl ether based on their spectroscopic data (IR, MS, 1H and 13CNMR). Metabolites 1 and 2 have been identified as new phytotoxins structurally related to zinniol (4). Additionally, 5-(3',3'-dimethylallyloxy)-7-methoxy-6-methyl-phthalide and 8-zinniol-2-(phenyl)-ethyl ether (3) were also isolated during the purification process.

  7. Sclerenchymatous ring as a barrier to phloem feeding by Asian citrus psyllid: Evidence from electrical penetration graph and visualization of stylet pathways

    Science.gov (United States)

    Asian citrus psyllid (ACP) feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas) bacteria that cause citrus greening disease. Sustained phloem ingestion by ACP on CLas infected plants is very important in pathogen acquisition and...

  8. Use of micro-CT to elucidate details of the anatomy and feeding of the Asian citrus psyllid Diaphorina citri Kuwayama, 1908 (Insecta: Hemiptera, Liviidae)

    Science.gov (United States)

    Huanglongbing (HLB), also known as citrus greening disease, is caused by plant-infecting bacteria. The most prominent pathogen within the Americas: United States of America, Mexico, and Brazil, is Candidatus Liberibacter asiaticus, which affects plants of the Family: Rutaceae, in particularly citrus...

  9. 76 FR 8603 - Citrus Seed Imports; Citrus Greening and Citrus Variegated Chlorosis

    Science.gov (United States)

    2011-02-15

    ... propagative seed of several Rutaceae (citrus family) genera from certain countries where citrus greening or... Rutaceae may be a pathway for the introduction of those diseases. The interim rule was necessary in order...), we amended the regulations to prohibit the importation of propagative seed of several...

  10. Mapping Resistance to Alternaria cucumerina in Cucumis melo.

    Science.gov (United States)

    Daley, James; Branham, Sandra; Levi, Amnon; Hassell, Richard; Wechter, Patrick

    2017-04-01

    Infection with Alternaria cucumerina causes Alternaria leaf blight (ALB), a disease characterized by lesion formation on leaves, leading to substantial yield and quality losses in Cucumis melo (melon). Although fungicides are effective against ALB, reduction in the frequency of application would be economically and environmentally beneficial. Resistant melon lines have been identified but the genetic basis of this resistance has not been determined. A saturated melon genetic map was constructed with markers developed through genotyping by sequencing of a recombinant inbred line population (F6 to F10; n = 82) derived from single-seed descent of a F2 population from a cross between the ALB-resistant parent MR-1 and the ALB-susceptible parent Ananas Yokneum. The population was evaluated for A. cucumerina resistance with an augmented block greenhouse study using inoculation with the wounded-leaf method. Multiple quantitative trait loci (QTL) mapping identified two QTL that explained 33.9% of variation in lesion area. Several candidate genes within range of these QTL were identified using the C. melo v3.5 genome. Markers linked to these QTL will be used to accelerate efforts to breed melon cultivars resistant to ALB.

  11. Inhibition of spore germination of Alternaria tenuis by sulfur dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Couey, H.M.

    1962-08-01

    As a part of a continuing study of SO/sub 2/ fumigation of table grapes, the effect of SO/sub 2/ on spores of an isolate of A. tenuis Auct. causing decay of table grapes was determined. The amount of SO/sub 2/ required to inhibit completely spore germination depended on availability of moisture and the temperature. At 20/sup 0/C, wet spores required 20-min exposure to 100 ppm SO/sub 2/ to prevent germination, but spores equilibrated at 90% relative humidity (RH) required 10-min exposure to 1000 ppm SO/sub 2/. Dry spores at 60% RH were unaffected by a 20-min exposure to 4000 ppm SO/sub 2/. Increasing the temperature in the range 5-20/sup 0/C increased effectiveness of the SO/sub 2/ treatment. A comparison of Alternaria with Botrytis cinerea Fr. (studied earlier) showed that wet spores of these organisms were about equally sensitive to SO/sub 2/, but that dry Alternaria spores were more resistant to SO/sub 2/ than dry Botrytis spores under comparable conditions.

  12. Activation of Melanin Synthesis in Alternaria infectoria by Antifungal Drugs.

    Science.gov (United States)

    Fernandes, Chantal; Prados-Rosales, Rafael; Silva, Branca M A; Nakouzi-Naranjo, Antonio; Zuzarte, Mónica; Chatterjee, Subhasish; Stark, Ruth E; Casadevall, Arturo; Gonçalves, Teresa

    2015-12-28

    The importance of Alternaria species fungi to human health ranges from their role as etiological agents of serious infections with poor prognoses in immunosuppressed individuals to their association with respiratory allergic diseases. The present work focuses on Alternaria infectoria, which was used as a model organism of the genus, and was designed to unravel melanin production in response to antifungals. After we characterized the pigment produced by A. infectoria, we studied the dynamics of 1,8-dihydroxynaphthalene (DHN)-melanin production during growth, the degree of melanization in response to antifungals, and how melanization affected susceptibility to several classes of therapeutic drugs. We demonstrate that A. infectoria increased melanin deposition in cell walls in response to nikkomycin Z, caspofungin, and itraconazole but not in response to fluconazole or amphotericin B. These results indicate that A. infectoria activates DHN-melanin synthesis in response to certain antifungal drugs, possibly as a protective mechanism against these drugs. Inhibition of DHN-melanin synthesis by pyroquilon resulted in a lower minimum effective concentration (MEC) of caspofungin and enhanced morphological changes (increased hyphal balloon size), characterized by thinner and less organized A. infectoria cell walls. In summary, A. infectoria synthesizes melanin in response to certain antifungal drugs, and its susceptibility is influenced by melanization, suggesting the therapeutic potential of drug combinations that affect melanin synthesis.

  13. Tale of the Huanglongbing Disease Pyramid in the Context of the Citrus Microbiome.

    Science.gov (United States)

    Wang, Nian; Stelinski, Lukasz L; Pelz-Stelinski, Kirsten S; Graham, James H; Zhang, Yunzeng

    2017-04-01

    The Huanglongbing (HLB) disease pyramid is composed of Liberibacters, psyllid vectors, citrus hosts, and the environment. The epidemiological outcomes for Liberibacter-associated plant diseases are collectively determined by the inherent relationships among plant-Liberibacters-psyllids, and how various environmental factors affect plant-Liberibacter-psyllid interactions. Citrus-Liberibacter-psyllid interactions occur in a complex microbiome system. In this review, we focus on the progress in understanding the HLB disease pyramid, and how the microbiome affects the HLB disease pyramid including the interaction between HLB and the citrus microbiome; the interaction between Liberibacters and psyllids; the interaction between Liberibacters and gut microbiota in psyllids; and the effect of HLB on selected above- and belowground citrus pathogens. Their implications for HLB management are also discussed.

  14. Morphological and Molecular Description of Phytophthora insolita Isolated from Citrus Orchard in India

    Directory of Open Access Journals (Sweden)

    Swapnil Bawage

    2013-01-01

    Full Text Available Citrus, an important cash crop in India, is adversely affected by Phytophthora nicotianae, P. palmivora, and P. citrophthora. Phytophthora insolita is known to be associated with citrus and reported for the first time in India. It is a rare and poorly characterized Phytophthora species, as its natural host and pathogenic impact are unclear. Previously, it was reported only in Taiwan and China; so to confirm our suspected isolate is P. insolita, regions of internal transcribed spacer, elongation factor, beta-tubulin, and cytochrome oxidase genes were sequenced. This study provides description of the lone Indian P. insolita isolate with respect to molecular identity, morphology, mating behaviour, and pathogenicity.

  15. Aislamiento, identificación y pruebas in vitro de cepas autóctonas de Bacillus subtilis como agente de biocontrol de Alternaria spp en Brassica oleracea var.italica.

    OpenAIRE

    Ñacato Suntaxi, Carolina Aracely; Valencia Gordón, María Fernanda

    2016-01-01

    There is an increasing consumer demand for quality food, a concept which mainly involves the availability of disease-free products and harmful to human health chemical waste, which is why the need for new options for sustainable management arises broccoli crop against the causative pathogen damage in inflorescence. The disease caused by the phytopathogenic fungus Alternaria spp is a major cause of damage to broccoli cultivars. Field sampling and laboratory investigations w...

  16. Airborne Alternaria and Cladosporium species and relationship with meteorological conditions in Eskisehir City, Turkey.

    Science.gov (United States)

    Erkara, Ismuhan Potoglu; Asan, Ahmet; Yilmaz, Veysel; Pehlivan, Sevil; Okten, Suzan Sarica

    2008-09-01

    Alternaria and Cladosporium, known as the most allergenic spores were first collected by means of Durham gravimetric sampler from Eskisehir atmosphere from January 1, 2000 to December 31, 2001. The daily, monthly and annual variations in spores/cm(2) of Cladosporium and Alternaria were recorded. During this period, a total of 10.231 spores belonging to Cladosporium and Alternaria genera were recorded. Of these spores, 5,103 were identified in 2000 and 5,128 in 2001. While 63.09% of the total spores were those of Cladosporium, 36.91% were of Alternaria. Relationships between airborne fungal spore presence and meteorological conditions were statistically investigated. A Shapiro-Wilk test revealed that the airborne Cladosporium and Alternaria spores differed from a normal distribution. Thus, a Friedmann test was performed followed by a Pearson Correlation Analysis. The effects of rainfall, temperature and wind speed on Cladosporium and Alternaria numbers were non-significant according to the sites and months (p > 0.05), but the effects of relative humidity on Cladosporium and Alternaria numbers were significant (p < 0.01). Spore concentrations reached to their highest levels in May 2001.

  17. Antifungal Activity of Essential Oils from Some Medicinal Plants of Iran against Alternaria alternate

    Directory of Open Access Journals (Sweden)

    I. Hadizadeh

    2009-01-01

    Full Text Available Problem statement: Increasing public concern over the level of pesticide residues in food especially fresh produce has built up adequate pressure for scientists to look for less hazardous and environmentally safer compounds for controlling post harvest diseases. Essential oils as registered food grade materials have the potential to be applied as alternative anti-fungal treatments for fresh fruits and vegetables. Approach: We present in this study, the identification of the essential oils with antifungal activity from some medicinal plants of Iran (nettle (Urtica dioica L., thyme (Thymus vulgaris L., eucalyptus (Eucalyptus spp., Rue (Ruta graveolens L. and common yarrow (Achillea millefolium L., and their potential application as "generally regarded as safe" antifungal compounds against Alternaria alternate on tomato as a model pathosystem. Results: Both the nettle and the thyme oils exhibited antifungal activity against A. alternata. The thyme oil exhibited a lower degree of inhibition 68.5 and 74.8% at 1500 and 2000 ppm, respectively. Spore germination and germ tube elongation of the pathogens in potato dextrose broth was strongly reduced in the presence of 1500 ppm of the nettle oil. The same concentration of this oil reduced the percentage of decayed tomatoes. The experiments on reducing the development of natural tomato rot gave similar results. Conclusions: Application of essential oils for postharvest disease control of fresh produce, as a novel emerging alternative to hazardous anti-fungal treatments will allow a safer and environmentally more acceptable management of postharvest diseases.

  18. Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

    Science.gov (United States)

    Sun, Hong; Gao, Shushan; Li, Xiaoming; Li, Chunshun; Wang, Bingui

    2013-03-01

    A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192, an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa, resulted in the isolation of nine known secondary metabolites, including four indole-diterpenoids: penijanthine A ( 1), paspaline ( 2), paspalinine ( 3), and penitrem A ( 4); three tricycloalternarene derivatives: tricycloalternarene 3a ( 5), tricycloalternarene 1b ( 6), and tricycloalternarene 2b ( 7); and two alternariol congeners: djalonensone ( 8) and alternariol ( 9). The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature. The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum, with inhibition zone diameters of 8 and 9 mm, respectively, at 100 μg/disk. To the best of our knowledge, this is the first report on the secondary metabolites of mangrove-derived A lternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus A lternaria.

  19. Variability among Alternaria solani isolates associated with early blight of tomato.

    Science.gov (United States)

    Varma, P Kishore; Singh, Sher; Gandhi, S K; Chaudhary, K

    2006-01-01

    Variability among isolates of Alternaria solani, the causal agent of early blight of tomato, from Northern and Southern parts of India was determined based on conidial morphology, pathogenicity tests and random amplified polymorphic DNA (RAPD) techniques. The isolates varied with respect to size of conidia and number of septa. The average size of conidia varied from 150-224.9 microm x 12.4-17.2 microm. The number of horizontal (4-14), vertical (0-3) and beak (0-8) septa also varied among the isolates. The test isolates differed in the virulence pattern on ten tomato genotypes under screen house conditions. Based on disease severity, test isolates were categorized into three main groups. Isolates RAS (Rohtak) and HAS-I (Hisar) were more virulent than all other isolates. None of the genotypes were completely resistant to all the test isolates. The analysis of RAPD profiles showed that there was a high level of genetic variability among the isolates of A. solani. The cluster analysis based on similarity coefficients separated the ten A. solani isolates into two major clusters. There was no evidence for geographical clustering of isolates with high levels of genetic similarity, suggesting that isolates are widely spread across India.

  20. Resistance to Alternaria solani in hybrids between a Solanum tuberosum haploid and S. raphanifolium.

    Science.gov (United States)

    Weber, B N; Jansky, S H

    2012-02-01

    Early blight of potato (Solanum tuberosum), caused by the foliar fungal pathogen Alternaria solani, is a major cause of economic loss in many potato-growing regions. Genetic resistance offers an opportunity to decrease fungicide usage while maintaining yield and quality. In this study, an early blight resistant clone of the diploid wild species S. raphanifolium was crossed as a male to a haploid (2n=2x) of cultivated potato. Hybrids were backcrossed to both parents. Eight families were created and evaluated for early blight resistance in the field. Families created by backcrossing to the wild species parent exhibited significantly lower relative area under the disease progress curve means than those from backcrossing to the cultivated parent, leading to the conclusion that S. raphanifolium contributes genes for early blight resistance. The mechanism of resistance in S. raphanifolium is unique because A. solani could not be recovered from lesions. Clones were identified with high levels of resistance and adaptation to the photoperiod of a temperate production region.

  1. A family of small cyclic amphipathic peptides (SCAmpPs) genes in citrus.

    Science.gov (United States)

    Belknap, William R; McCue, Kent F; Harden, Leslie A; Vensel, William H; Bausher, Michael G; Stover, Ed

    2015-04-16

    Citrus represents a crop of global importance both in economic impact and significance to nutrition. Citrus production worldwide is threatened by the disease Huanglongbing (HLB), caused by the phloem-limited pathogen Candidatus Liberibacter spp.. As a source of stable HLB-resistance has yet to be identified, there is considerable interest in characterization of novel disease-associated citrus genes. A gene family of Small Cyclic Amphipathic Peptides (SCAmpPs) in citrus is described. The citrus genomes contain 100-150 SCAmpPs genes, approximately 50 of which are represented in the citrus EST database. These genes encode small ~50 residue precursor proteins that are post-translationally processed, releasing 5-10 residue cyclic peptides. The structures of the SCAmpPs genes are highly conserved, with the small coding domains interrupted by a single intron and relatively extended untranslated regions. Some family members are very highly transcribed in specific citrus tissues, as determined by representation in tissue-specific cDNA libraries. Comparison of the ESTs of related SCAmpPs revealed an unexpected evolutionary profile, consistent with targeted mutagenesis of the predicted cyclic peptide domain. The SCAmpPs genes are displayed in clusters on the citrus chromosomes, with apparent association with receptor leucine-rich repeat protein arrays. This study focused on three SCAmpPs family members with high constitutive expression in citrus phloem. Unexpectedly high sequence conservation was observed in the promoter region of two phloem-expressed SCAmpPs that encode very distinct predicted cyclic products. The processed cyclic product of one of these phloem SCAmpPs was characterized by LC-MS-MS analysis of phloem tissue, revealing properties consistent with a K(+) ionophore. The SCAmpPs amino acid composition, protein structure, expression patterns, evolutionary profile and chromosomal distribution are consistent with designation as ribosomally synthesized defense

  2. Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam

    Science.gov (United States)

    Schena, Leonardo; Jung, Thomas; Evoli, Maria; Pane, Antonella; Van Hoa, Nguyen; Van Tri, Mai; Wright, Sandra; Ramstedt, Mauritz; Olsson, Christer; Faedda, Roberto; Magnano di San Lio, Gaetano

    2017-01-01

    Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with ‘King’ mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch’s postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on ‘Carrizo’ citrange (C. sinensis ‘Washington Navel’ x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity. PMID:28208159

  3. Nested-PCR Detection of the pathogen of Citrus Huanglongbing on Clausena iansium and Murraya paniculata%用Nested-PCR检测广西黄皮与九里香黄龙病病原

    Institute of Scientific and Technical Information of China (English)

    邓崇岭; 陈传武; 赵小龙; 付慧敏; 陈国平; 白先进; 娄兵海; 吴礽超

    2010-01-01

    运用Nested-PCR技术对来自广西部分市、县的40个黄皮和九里香进行柑桔黄龙病(Citrus Huanglongbing,HLB)病原检测,结果表明:从部分黄皮和九里香样品抽提的DNA中,可扩增出一条特异性的400bp条带,说明广西种植的黄皮和九里香均可感染黄龙病;在柑桔黄龙病疫区,黄皮和九里香黄龙病感染率分别为35.0%和40.0%,黄龙病感染率已相当高.为了减少柑桔黄龙病的发生,有利于对柑桔黄龙病进行综合防控,不宜在柑桔种植区栽种黄皮和九里香,铲除已感染黄龙病的植株.

  4. Characterization of a Proposed Dichorhavirus Associated with the Citrus Leprosis Disease and Analysis of the Host Response

    Science.gov (United States)

    Cruz-Jaramillo, José Luis; Ruiz-Medrano, Roberto; Rojas-Morales, Lourdes; López-Buenfil, José Abel; Morales-Galván, Oscar; Chavarín-Palacio, Claudio; Ramírez-Pool, José Abrahán; Xoconostle-Cázares, Beatriz

    2014-01-01

    The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV) and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata—channels interconnecting neighboring cells—suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants. PMID:25004279

  5. Characterization of a Proposed Dichorhavirus Associated with the Citrus Leprosis Disease and Analysis of the Host Response

    Directory of Open Access Journals (Sweden)

    José Luis Cruz-Jaramillo

    2014-07-01

    Full Text Available The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata—channels interconnecting neighboring cells—suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants.

  6. Characterization of a proposed dichorhavirus associated with the citrus leprosis disease and analysis of the host response.

    Science.gov (United States)

    Cruz-Jaramillo, José Luis; Ruiz-Medrano, Roberto; Rojas-Morales, Lourdes; López-Buenfil, José Abel; Morales-Galván, Oscar; Chavarín-Palacio, Claudio; Ramírez-Pool, José Abrahán; Xoconostle-Cázares, Beatriz

    2014-07-07

    The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV) and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata-channels interconnecting neighboring cells-suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants.

  7. PR gene families of citrus: their organ specific-biotic and abiotic inducible expression profiles based on ESTs approach

    Directory of Open Access Journals (Sweden)

    Magnólia A. Campos

    2007-01-01

    Full Text Available In silico expression profiles, of the discovered 3,103 citrus ESTs putatively encoding for PR protein families (PR-1 to PR-17, were evaluated using the Brazil citrus genome EST CitEST/database. Hierarchical clustering was displayed to identify similarities in expression patterns among citrus PR-like gene families (PRlgf in 33 selected cDNA libraries. In this way, PRlgf preferentially expressed by organ and citrus species, and library conditions were highlighted. Changes in expression profiles of clusters for each of the 17 PRlgf expressed in organs infected by pathogens or drought-stressed citrus species were displayed for relative suppression or induction gene expression in relation to the counterpart control. Overall, few PRlgf showed expression 2-fold higher in pathogen-infected than in uninfected organs, even though the differential expression profiles displayed have been quite diverse among studied species and organs. Furthermore, an insight into some contigs from four PRlgf pointed out putative members of multigene families. They appear to be evolutionarily conserved within citrus species and/or organ- or stress-specifically expressed. Our results represent a starting point regarding the extent of expression pattern differences underlying PRlgf expression and reveal genes that may prove to be useful in studies regarding biotechnological approaches or citrus resistance markers.

  8. Phytophthora parasitica transcriptome, a new concept in the understanding of the citrus gummosis

    Directory of Open Access Journals (Sweden)

    Daniel D. Rosa

    2007-01-01

    Full Text Available Due to the economic importance of gummosis disease for the citriculture, studies on P. parasitica-Citrus interaction comprise a significant part in the Brazilian Citrus genome data bank (CitEST. Among them, two cDNA libraries constructed from two different growth conditions of the P. parasitica pathogen are included which has generated the PP/CitEST database (CitEST - Center APTA Citros Sylvio Moreira/IAC- Millennium Institute. Through this genomic approach and clustering analyses the following has been observed: out of a total of 13,285 available in the Phytophthora parasitica database, a group of 4,567 clusters was formed, comprising 2,649 singlets and 1,918 contigs. Out of a total of 4,567 possible genes, only 2,651 clusters were categorized; among them, only 4.3% shared sequence similarities with pathogenicity factors and defense. Some of these possible genes (103 corresponding to 421 ESTs, were characterized by phylogenetic analysis and discussed. A comparison made with the COGEME database has shown homology which may be part of an evolutionary pathogenicity pathway present in Phytophthora and also in other fungi. Many of the genes which were identified here, which may encode proteins associated to mechanisms of citrus gummosis pathogenicity, represent only one facet of the pathogen-host Phytophthora - Citrus interaction.

  9. Morphogenetic Alterations of Alternaria alternata Exposed to Dicarboximide Fungicide, Iprodione

    Science.gov (United States)

    Kim, Eunji; Lee, Hye Min; Kim, Young Ho

    2017-01-01

    Fungicide-resistant Alternaria alternata impede the practical control of the Alternaria diseases in crop fields. This study aimed to investigate cytological fungicide resistance mechanisms of A. alternata against dicarboximide fungicide iprodione. A. alternata isolated from cactus brown spot was cultured on potato-dextrose agar (PDA) with or without iprodione, and the fungal cultures with different growth characteristics from no, initial and full growth were observed by light and electron microscopy. Mycelia began to grow from one day after incubation (DAI) and continued to be in full growth (control-growth, Con-G) on PDA without fungicide, while on PDA with iprodione, no fungal growth (iprodione-no growth, Ipr-N) occurred for the first 3 DAI, but once the initial growth (iprodione-initial growth, Ipr-I) began at 4–5 DAI, the colonies grew and expanded continuously to be in full growth (iprodione-growth, Ipr-G), suggesting Ipr-I may be a turning moment of the morphogenetic changes resisting fungicidal toxicity. Con-G formed multicellular conidia with cell walls and septa and intact dense cytoplasm. In Ipr-N, fungal sporulation was inhibited by forming mostly undeveloped unicellular conidia with degraded and necrotic cytoplasm. However, in Ipr-I, conspicuous cellular changes occurred during sporulation by forming multicellular conidia with double layered (thickened) cell walls and accumulation of proliferated lipid bodies in the conidial cytoplasm, which may inhibit the penetration of the fungicide into conidial cells, reducing fungicide-associated toxicity, and may be utilized as energy and nutritional sources, respectively, for the further fungal growth to form mature colonies as in Ipr-G that formed multicellular conidia with cell walls and intact cytoplasm with lipid bodies as in Con-G. PMID:28167893

  10. Characterization of a sabinene synthase gene from rough lemon (Citrus jambhiri).

    Science.gov (United States)

    Kohzaki, Keisuke; Gomi, Kenji; Yamasaki-Kokudo, Yumiko; Ozawa, Rika; Takabayashi, Junji; Akimitsu, Kazuya

    2009-10-15

    We previously isolated two putative monoterpene synthase genes, RlemTPS1 and RlemTPS2, from rough lemon (Citrus jambhiri) and showed that gene expression of RlemTPS2 was induced by microbial attack. The protein product of RlemTPS2 was obtained using a prokaryotic expression system, and GC and GC-MS of monoterpene synthesis by RlemTPS2 determined that RlemTPS2 encodes a sabinene synthase. Sabinene has antifungal activity toward Alternaria alternata. Furthermore, site-directed mutagenesis identified one amino acid, Ile, located at the front of the metal ion binding motif as an important residue for the product specificity of sabinene synthase.

  11. Microbes Associated with Freshly Prepared Juices of Citrus and Carrots

    Directory of Open Access Journals (Sweden)

    Kamal Rai Aneja

    2014-01-01

    Full Text Available Fruit juices are popular drinks as they contain antioxidants, vitamins, and minerals that are essential for human being and play important role in the prevention of heart diseases, cancer, and diabetes. They contain essential nutrients which support the growth of acid tolerant bacteria, yeasts, and moulds. In the present study, we have conducted a microbiological examination of freshly prepared juices (sweet lime, orange, and carrot by serial dilution agar plate technique. A total of 30 juice samples were examined for their microbiological quality. Twenty-five microbial species including 9 bacterial isolates, 5 yeast isolates, and 11 mould isolates were isolated from juices. Yeasts and moulds were the main cause of spoilage of juices. Aspergillus flavus and Rhodotorula mucilaginosa were observed in the maximum number of juice samples. Among bacteria Bacillus cereus and Serratia were dominant. Escherichia coli and Staphylococcus aureus were detected in few samples. Candida sp., Curvularia, Colletotrichum, and Acetobacter were observed only in citrus juice samples. Alternaria, Aspergillus terreus, A. niger, Cladosporium, and Fusarium were also observed in tested juice samples. Some of the microorganisms detected in these juice samples can cause disease in human beings, so there is need for some guidelines that can improve the quality of fruit juices.

  12. Selection of Small Synthetic Antimicrobial Peptides Inhibiting Xanthomonas citri subsp. citri Causing Citrus Canker

    Science.gov (United States)

    Choi, Jeahyuk; Park, Euiho; Lee, Se-Weon; Hyun, Jae-Wook; Baek, Kwang-Hyun

    2017-01-01

    Citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. Small synthetic antimicrobial peptides (AMPs) could be a promising alternative. Fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. Each hexapeptide showed different antimicrobial spectrum against Bacillus, Pseudomonas, Xanthomonas, and Candida species. Intriguingly, BHC10 showed bactericidal activity exclusively on Xanthomonas citri subsp. citri (Xcc), while BHC7 was none-active exclusively against two Pseudomonas spp. at concentration of 100 μg/ml suggesting potential selectivity constrained in hexapeptide frame. Three hexapeptides, BHC02, 06 and 11, showed bactericidal activities against various Xcc strains at concentration of 10 μg/ml. When they were co-infiltrated with pathogens into citrus leaves the disease progress was suppressed significantly. Further study would be needed to confirm the actual disease control capacity of the selected hexapeptides. PMID:28167892

  13. Control of virus diseases of citrus.

    Science.gov (United States)

    Lee, Richard F

    2015-01-01

    Citrus is thought to have originated in Southeast Asia and horticulturally desirable clonal selections have been clonally cultivated for hundreds of years. While some citrus species have nucellar embryony, most cultivation of citrus has been by clonal propagation to ensure that propagated plants have the same traits as the parent selection. Clonal propagation also avoids juvenility, and the propagated plants produce fruit sooner. Because of the clonal propagation of citrus, citrus has accumulated a large number of viruses; many of these viruses are asymptomatic until a susceptible rootstock and/or scion is encountered. The viruses reported to occur in citrus will be summarized in this review. Methods of therapy to clean selected clones from viruses will be reviewed; the use of quarantine, clean stock, and certification programs for control of citrus viruses and other strategies to control insect spread citrus viruses, such as mild strain cross-protection and the use of pest management areas will be discussed.

  14. Application of ultraviolet-C light on oranges for the inactivation of postharvest wound pathogens

    Science.gov (United States)

    Germicidal effects of ultraviolet-C (UV-C) light on the postharvest wound pathogens of citrus fruits namely Penicillium digitatum and Penicillium italicum were investigated. P. digitatum and P. italicum spores were inoculated (4.00 – 4.50 log cfu/ orange) onto Washington navel oranges (Citrus sinens...

  15. Phytochemical, antimicrobial, and antioxidant activities of different citrus juice concentrates.

    Science.gov (United States)

    Oikeh, Ehigbai I; Omoregie, Ehimwenma S; Oviasogie, Faith E; Oriakhi, Kelly

    2016-01-01

    The search for new antimicrobial compounds is ongoing. Its importance cannot be overemphasized in an era of emerging resistant pathogenic organisms. This study therefore investigated the phytochemical composition and antioxidant and antimicrobial activities of different citrus juice concentrates. Fruit juices of Citrus tangerine (tangerine), Citrus paradisi (grape), Citrus limon (lemon), and Citrus aurantifolia (lime) were evaluated. Antimicrobial activities against five bacterial and three fungal strains were evaluated. The results revealed the presence of alkaloids, flavonoids, steroids, terpenoids, saponins, cardiac glycosides, and reducing sugars in all the juice concentrates. DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging capacities varied with tangerine and grape juices having better scavenging capacities than lemon and lime juices. Grape juice was observed to have a significantly higher (P < 0.05) ferric-reducing antioxidant potential (FRAP) value (364.2 ± 10.25 μmol/L Fe(II)/g of the extract) than the reference antioxidant, ascorbic acid (312.88 ± 5.61 μmol/L). Antimicrobial studies revealed differential antimicrobial activities against different microbial strains. Zones of inhibition ranging from 4 to 26 mm were observed for the antibacterial tests with 0-24 mm for antifungal test. Minimum inhibitory concentrations (MIC) and minimum bacteriostatic concentrations (MBC) for concentrates against bacterial strains ranged from 12.5 to 200 μg/mL. Lemon and lime juice concentrates had lower MIC and MBC values with orange and tangerine having the highest values. Minimum fungicidal concentrations ranged from 50 to 200 μg/mL. The results of this study suggest that these juice concentrates may have beneficial antimicrobial roles that can be exploited in controlling unwanted microbial growth.

  16. Barrier disrupting effects of alternaria alternata extract on bronchial epithelium from asthmatic donors.

    Directory of Open Access Journals (Sweden)

    Marina S Leino

    Full Text Available Sensitization and exposure to the allergenic fungus Alternaria alternata has been associated with increased risk of asthma and asthma exacerbations. The first cells to encounter inhaled allergens are epithelial cells at the airway mucosal surface. Epithelial barrier function has previously been reported to be defective in asthma. This study investigated the contribution of proteases from Alternaria alternata on epithelial barrier function and inflammatory responses and compared responses of in vitro cultures of differentiated bronchial epithelial cells derived from severely asthmatic donors with those from non-asthmatic controls. Polarised 16HBE cells or air-liquid interface (ALI bronchial epithelial cultures from non-asthmatic or severe asthmatic donors were challenged apically with extracts of Alternaria and changes in inflammatory cytokine release and transepithelial electrical resistance (TER were measured. Protease activity in Alternaria extracts was characterised and the effect of selectively inhibiting protease activity on epithelial responses was examined using protease inhibitors and heat-treatment. In 16HBE cells, Alternaria extracts stimulated release of IL-8 and TNFα, with concomitant reduction in TER; these effects were prevented by heat-treatment of the extracts. Examination of the effects of protease inhibitors suggested that serine proteases were the predominant class of proteases mediating these effects. ALI cultures from asthmatic donors exhibited a reduced IL-8 response to Alternaria relative to those from healthy controls, while neither responded with increased thymic stromal lymphopoietin (TSLP release. Only cultures from asthmatic donors were susceptible to the barrier-weakening effects of Alternaria. Therefore, the bronchial epithelium of severely asthmatic individuals may be more susceptible to the deleterious effects of Alternaria.

  17. Citrus Limonoids: Analysis, Bioactivity, and Biomedical Prospects

    Science.gov (United States)

    This publication is a review of the chemistry, biochemistry and bioactivity of limonoids occurring in citrus. The review chronologically relates the evolution of research in citrus limonoids beginning with their association with bitterness development in citrus juices. The chemical and biochemical...

  18. Soil Micronutrients and Citrus Growth

    Institute of Scientific and Technical Information of China (English)

    OUYANGTAO

    1993-01-01

    By using nutritional diagnosis of citrus leaves and determining soil micronutrients,the relationship between soil micronutrients and citrus growth in southern China has been studied.Studies showed that there was a significant positive correlation between available micronutrients (such as Zn,Mo,Cu)in the soil and the corresponding nutrients in citrus leaves.Thus,one can roughly learn of the sufficiency or deficiency of certain nutrients in soils by analyzing citrus leaves.Rational spray of Zn B or Mo fertilizer not only improved citrus yields but also increased the total sugar of Satsuma mandarin and of Xinhui orange by 2.9 and 17.2% respectively compared with the control.Spraying Mo fertilizer increased the vitamin C content of Satsuma mandarin juice by 4.7%-8.4%,maturated fruits 7-10 days earlier and gave the peel a brighter color.The ultramicroscopic characteristics of Zn-deficient citrus leaves were investigated under an electron microscope.Results showed that the Zn-deficient leaf cell was characterized mainly by poor cytoplasm,endoplasmic reticula and ribosomes and by big starch grains in the chloroplast.As a result of spraying Zn fertilizer the structure of the cell returned to normal,the cytoplasm became rich and the amount of chloroplast increased.There also appeared a great deal of multiform endoplasmic reticula,thus promoting the photosynthesis of Zn-deficient plants.This provides a cytologico-theoretical basis for fertilization of high-yielding citrus trees.

  19. Botanicals, selective insecticides, and predators to control Diaphorina citri (Hemiptera: Liviidae) in citrus orchards.

    Science.gov (United States)

    Khan, Azhar A; Afzal, Muhammad; Qureshi, Jawwad A; Khan, Arif M; Raza, Abubakar M

    2014-12-01

    The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically important disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecticides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad-spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, average 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Aneglei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides. © 2014 Institute of Zoology, Chinese Academy of Sciences.

  20. The Arabidopsis thaliana-Alternaria brassicicola pathosystem: A model interaction for investigating seed transmission of necrotrophic fungi.

    Science.gov (United States)

    Pochon, Stephanie; Terrasson, Emmanuel; Guillemette, Thomas; Iacomi-Vasilescu, Beatrice; Georgeault, Sonia; Juchaux, Marjorie; Berruyer, Romain; Debeaujon, Isabelle; Simoneau, Philippe; Campion, Claire

    2012-05-09

    Seed transmission constitutes a major component of the parasitic cycle for several fungal pathogens. However, very little is known concerning fungal or plant genetic factors that impact seed transmission and mechanisms underlying this key biological trait have yet to be clarified. Such lack of available data could be probably explained by the absence of suitable model pathosystem to study plant-fungus interactions during the plant reproductive phase. Here we report on setting up a new pathosystem that could facilitate the study of fungal seed transmission. Reproductive organs of Arabidopsis thaliana were inoculated with Alternaria brassicicola conidia. Parameters (floral vs fruit route, seed collection date, plant and silique developmental stages) that could influence the seed transmission efficiency were tested to define optimal seed infection conditions. Microscopic observations revealed that the fungus penetrates siliques through cellular junctions, replum and stomata, and into seed coats either directly or through cracks. The ability of the osmosensitive fungal mutant nik1Δ3 to transmit to A. thaliana seeds was analyzed. A significant decrease in seed transmission rate was observed compared to the wild-type parental strain, confirming that a functional osmoregulation pathway is required for efficient seed transmission of the fungus. Similarly, to test the role of flavonoids in seed coat protection against pathogens, a transparent testa Arabidopsis mutant (tt4-1) not producing any flavonoid was used as host plant. Unexpectedly, tt4-1 seeds were infected to a significantly lower extent than wild-type seeds, possibly due to over-accumulation of other antimicrobial metabolites. The Arabidopsis thaliana-Alternaria brassicicola pathosystem, that have been widely used to study plant-pathogen interactions during the vegetative phase, also proved to constitute a suitable model pathosystem for detailed analysis of plant-pathogen interactions during the reproductive

  1. The Arabidopsis thaliana-Alternaria brassicicola pathosystem: A model interaction for investigating seed transmission of necrotrophic fungi

    Directory of Open Access Journals (Sweden)

    Pochon Stephanie

    2012-05-01

    Full Text Available Abstract Background Seed transmission constitutes a major component of the parasitic cycle for several fungal pathogens. However, very little is known concerning fungal or plant genetic factors that impact seed transmission and mechanisms underlying this key biological trait have yet to be clarified. Such lack of available data could be probably explained by the absence of suitable model pathosystem to study plant-fungus interactions during the plant reproductive phase. Results Here we report on setting up a new pathosystem that could facilitate the study of fungal seed transmission. Reproductive organs of Arabidopsis thaliana were inoculated with Alternaria brassicicola conidia. Parameters (floral vs fruit route, seed collection date, plant and silique developmental stages that could influence the seed transmission efficiency were tested to define optimal seed infection conditions. Microscopic observations revealed that the fungus penetrates siliques through cellular junctions, replum and stomata, and into seed coats either directly or through cracks. The ability of the osmosensitive fungal mutant nik1Δ3 to transmit to A. thaliana seeds was analyzed. A significant decrease in seed transmission rate was observed compared to the wild-type parental strain, confirming that a functional osmoregulation pathway is required for efficient seed transmission of the fungus. Similarly, to test the role of flavonoids in seed coat protection against pathogens, a transparent testa Arabidopsis mutant (tt4-1 not producing any flavonoid was used as host plant. Unexpectedly, tt4-1 seeds were infected to a significantly lower extent than wild-type seeds, possibly due to over-accumulation of other antimicrobial metabolites. Conclusions The Arabidopsis thaliana-Alternaria brassicicola pathosystem, that have been widely used to study plant-pathogen interactions during the vegetative phase, also proved to constitute a suitable model pathosystem for detailed analysis

  2. Gender differences and effect of photophase on Asian citrus psyllid (Diaphorina citri Kuwayama) feeding behavior

    Science.gov (United States)

    Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), thought to be primarily a phloem-feeding insect, transmits the presumptive pathogen for Huanglongbing, ‘Candidatus Liberibacter asiaticus’. Because this bacterium is restricted to the phloem and bacterial transmission is the res...

  3. High species diversity in Colletotrichum associated with citrus diseases in Europe

    NARCIS (Netherlands)

    Guarnaccia, V.; Groenewald, J.Z.; Polizzi, G.; Crous, P.W>

    2017-01-01

    Species of Colletotrichum are considered important plant pathogens, saprobes, and endophytes on a wide range of plant hosts. Several species are well-known on citrus, either as agents of pre- or post-harvest infections, such as anthracnose, postbloom fruit drop, tear stain and stem-end rot on fruit,

  4. Potassium sorbate residue levels and persistence in citrus fruit as detected by a simple colorimetric method

    Science.gov (United States)

    Postharvest applications of potassium sorbate (PS) to fresh citrus fruit control fungal decay pathogens, such as Penicillium digitatum, cause of green mold. Although PS effectiveness has been examined repeatedly, little is known about PS residues. A colorimetric method that employed extraction of th...

  5. Spatial Genetic Structure of Coffee-Associated Xylella fastidiosa Populations Indicates that Cross Infection Does Not Occur with Sympatric Citrus Orchards.

    Science.gov (United States)

    Francisco, Carolina S; Ceresini, Paulo C; Almeida, Rodrigo P P; Coletta-Filho, Helvécio D

    2017-04-01

    Xylella fastidiosa, an economically important plant-pathogenic bacterium, infects both coffee and citrus trees in Brazil. Although X. fastidiosa in citrus is well studied, knowledge about the population structure of this bacterium infecting coffee remains unknown. Here, we studied the population structure of X. fastidiosa infecting coffee trees in São Paulo State, Brazil, in four regions where citrus is also widely cultivated. Genotyping of over 500 isolates from coffee plants using 14 genomic microsatellite markers indicated that populations were largely geographically isolated, as previously found with populations of X. fastidiosa infecting citrus. These results were supported by a clustering analysis, which indicated three major genetic groups among the four sampled regions. Overall, approximately 38% of isolates showed significant membership coefficients not related to their original geographical populations (i.e., migrants), characterizing a significant degree of genotype flow among populations. To determine whether admixture occurred between isolates infecting citrus and coffee plants, one site with citrus and coffee orchards adjacent to each other was selected; over 100 isolates were typed from each host plant. No signal of natural admixture between citrus- and coffee-infecting isolates was found; artificial cross-infection assays with representative isolates also yielded no successful cross infection. A comparison determined that X. fastidiosa populations from coffee have higher genetic diversity and allelic richness compared with citrus. The results showed that coffee and citrus X. fastidiosa populations are effectively isolated from each other and, although coffee populations are spatially structured, migration has an important role in shaping diversity.

  6. Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro.

    Science.gov (United States)

    Ivanović, Žarko; Perović, Tatjana; Popović, Tatjana; Blagojević, Jovana; Trkulja, Nenad; Hrnčić, Snježana

    2017-02-01

    Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (Citrus reticulata) in Montenegro, using multilocus sequence analysis of gyrB, rpoD, and gap1 gene sequences. Gene sequences from a collection of 54 reference pathotype strains of P. syringae from the Plant Associated and Environmental Microbes Database (PAMDB) was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of gyrB, rpoD, and gap1 gene sequences showed that P. syringae pv. syringae causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for P. syringae control.

  7. Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro

    Science.gov (United States)

    Ivanović, Žarko; Perović, Tatjana; Popović, Tatjana; Blagojević, Jovana; Trkulja, Nenad; Hrnčić, Snježana

    2017-01-01

    Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (Citrus reticulata) in Montenegro, using multilocus sequence analysis of gyrB, rpoD, and gap1 gene sequences. Gene sequences from a collection of 54 reference pathotype strains of P. syringae from the Plant Associated and Environmental Microbes Database (PAMDB) was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of gyrB, rpoD, and gap1 gene sequences showed that P. syringae pv. syringae causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for P. syringae control. PMID:28167885

  8. LRR-RLK family from two Citrus species: genome-wide identification and evolutionary aspects.

    Science.gov (United States)

    Magalhães, Diogo M; Scholte, Larissa L S; Silva, Nicholas V; Oliveira, Guilherme C; Zipfel, Cyril; Takita, Marco A; De Souza, Alessandra A

    2016-08-12

    Leucine-rich repeat receptor-like kinases (LRR-RLKs) represent the largest subfamily of plant RLKs. The functions of most LRR-RLKs have remained undiscovered, and a few that have been experimentally characterized have been shown to have important roles in growth and development as well as in defense responses. Although RLK subfamilies have been previously studied in many plants, no comprehensive study has been performed on this gene family in Citrus species, which have high economic importance and are frequent targets for emerging pathogens. In this study, we performed in silico analysis to identify and classify LRR-RLK homologues in the predicted proteomes of Citrus clementina (clementine) and Citrus sinensis (sweet orange). In addition, we used large-scale phylogenetic approaches to elucidate the evolutionary relationships of the LRR-RLKs and further narrowed the analysis to the LRR-XII group, which contains several previously described cell surface immune receptors. We built integrative protein signature databases for Citrus clementina and Citrus sinensis using all predicted protein sequences obtained from whole genomes. A total of 300 and 297 proteins were identified as LRR-RLKs in C. clementina and C. sinensis, respectively. Maximum-likelihood phylogenetic trees were estimated using Arabidopsis LRR-RLK as a template and they allowed us to classify Citrus LRR-RLKs into 16 groups. The LRR-XII group showed a remarkable expansion, containing approximately 150 paralogs encoded in each Citrus genome. Phylogenetic analysis also demonstrated the existence of two distinct LRR-XII clades, each one constituted mainly by RD and non-RD kinases. We identified 68 orthologous pairs from the C. clementina and C. sinensis LRR-XII genes. In addition, among the paralogs, we identified a subset of 78 and 62 clustered genes probably derived from tandem duplication events in the genomes of C. clementina and C. sinensis, respectively. This work provided the first comprehensive

  9. Sequencing the Major Mycosphaerella Pathogens of Wheat and Banana

    NARCIS (Netherlands)

    Kema, G.H.; Dunkle, L.D.; Churchill, A.C.; Carlier, J.; James, A.; Souza, M.T.; Crous, P.W.; Roux, N.; Lee, T.A. van der; Wiitenberg, A.; Lindquist, E.; Grigoriev, I.; Bristow, J.; Goodwin, S.B.

    2007-01-01

    Mycosphaerella is one of the largest genera of plant pathogenic fungi with more than 1,000 named species, many of which are important pathogens causing leaf spotting diseases in a wide variety of crops including cereals, citrus, banana, eucalypts, soft fruits, and horticultural crops. A few species

  10. Sequencing the Major Mycosphaerella Pathogens of Wheat and Banana

    NARCIS (Netherlands)

    Kema, G.H.J.

    2009-01-01

    Mycosphaerella is one of the largest genera of plant-pathogenic fungi with more than 1,000 named species, many of which are important pathogens causing leaf spotting diseases in a wide variety of crops including cereals, citrus, banana, eucalypts, soft fruits and horticultural crops. A few species

  11. Systemic jasmonic acid modulation in mycorrhizal tomato plants and its role in induced resistance against Alternaria alternata.

    Science.gov (United States)

    Nair, A; Kolet, S P; Thulasiram, H V; Bhargava, S

    2015-05-01

    Tomato plants colonised with the arbuscular mycorrhizal (AM) fungus Glomus fasciculatum show systemic induced resistance to the foliar pathogen Alternaria alternata, as observed in interactions of other AM-colonised plants with a range of pathogens. The role of jasmonic (JA) and salicylic (SA) acid in expression of this mycorrhiza-induced resistance (MIR) against A. alternata was studied by measuring: (i) activity of enzymes reported to be involved in their biosynthesis, namely lipoxygenase (LOX) and phenylammonia lyase (PAL); and (ii) levels of methyl jasmonate (MeJA) and SA. Transcript abundance of some defence genes associated with JA and SA response pathways were also studied. Both LOX and PAL activity increased twofold in response to pathogen application to control plants. AM-colonised plants had three-fold higher LOX activity compared to control plants, but unlike controls, this did not increase further in response to pathogen application. Higher LOX activity in AM-colonised plants correlated with four-fold higher MeJA in leaves of AM-colonised plants compared to controls. Treatment of plants with the JA biosynthesis inhibitor salicylhydroxamic acid (SHAM) led to 50% lower MeJA in both control and AM-colonised plants and correlated with increased susceptibility to A. alternata, suggesting a causal role for JA in expression of MIR against the pathogen. Genes involved in JA biosynthesis (OPR3) and response (COI1) showed six- and 42-fold higher expression, respectively, in leaves of AM-colonised plants compared to controls. AM-colonised plants also showed increased expression of the SA response gene PR1 and that of the wound-inducible polypeptide prosystemin. Our results suggest that the systemic increase in JA in response to AM colonisation plays a key role in expression of MIR against A. alternata.

  12. CONTROLE DE ALTERNARIA SOLANI COM FUNGICIDAS NA CULTURA DO TOMATEIRO CONTROL OF ALTERNARIA SOLANI WITH FUNGICIDES IN TOMATO PLANTS

    Directory of Open Access Journals (Sweden)

    Fabrício Silva Coelho

    2011-06-01

    Full Text Available A pinta-preta, causada pelo fungo Alternaria solani, caracteriza-se por ser uma importante e destrutiva doença da cultura do tomate, sob condições de alta temperatura e umidade. Objetivou-se avaliar a eficiência de diferentes fungicidas no controle da Alternaria solani na cultura do tomateiro na região de Lavras (MG. O experimento foi desenvolvido na Universidade Federal de Lavras - Departamento de Agricultura, no período de novembro de 2004 a janeiro de 2005. O delineamento experimental foi o de blocos casualizados com 10 tratamentos e quatro repetições. Cada parcela composta por 12 plantas. As aplicações foram realizadas com um pulverizador costal manual (45 lbf/pol2, volume de aplicação de 800 L•ha-1, totalizando sete aplicações, com intervalos de sete dias. Foram realizadas cinco avaliações para a severidade foliar da doença com o uso de escala diagramática. Todos os fungicidas apresentaram potencial de controle da pinta-preta dentro das características inerentes ao seu grupo químico. Os melhores níveis de controle foram obtidos com os tratamentos Chlorothalonil 500 g•L-1 + Tetraconazole 20 g•L-1 (dosagem 200 mL•100 L-1, Chlorothalonil 400 g•L-1+ Oxicloreto de Cobre 420 g•kg-1 e Chlorothalonil 750 g•kg-1 + Tetraconazole 20 g•kg-1 (dosagem 150 g•100 L-1. Tetraconazole 100 g•L-1 proporcionou os menores níveis de controle.The early blight disease on tomato, caused by the fungus Alternaria solani, is referred to in importance due its destructive power, under conditions of high temperature and humidity. This study aimed to evaluate the effectiveness of various fungicides in your control in the region of Lavras-MG, Brazil. The experiment was conducted at the Federal University of Lavras, Department of Agriculture in the period from November 2004 to January 2005. The experimental design was randomized blocks with 10 treatments and four replications, each plot comprise 12 plants. The applications were made

  13. Preliminary study on three pathogens with potential biological control in Barnyard grass (Echinochloa crus galli)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ More than 10 species of pathogenic fungi were isolated from the naturally infected leaves of barnyard grass (Echinochloa crus-galli) in paddy. After preliminary bioassaying, it was found that the Alternaria alternata (Fr.) keissler(AA), Exserohilum monoceras (EM),and "99-10" were three potential agents for biological control of barnyard grass.

  14. Antifungal Effect of the Aqueous and Ethanolic Avicennia marina Extracts on Alternaria citri and Penicillium digitatum

    Directory of Open Access Journals (Sweden)

    Behrooz Alizadeh Behbahani

    2016-02-01

    Full Text Available Background Plants have a great potential for producing new drugs of great benefit to mankind. There are many approaches to the search for new biologically active principles in higher plants. Objectives The aim of this study was to determine antifungal effect of the aqueous and ethanolic extracts of Avicennia marina on Penicillium digitatum and Alternaria citri in vitro. Materials and Methods In this experimental study, antimicrobial effects of extract were determined by screening antimicrobial activity and disk agar diffusion test in 20, 40, 60 and 80 mg/mL concentration of the extract against P. digitatum and A. citri. Minimum inhibitory concentration (MIC and minimum fungicidal concentration (MFC were determined by incorporating various concentrations of extracts in Sabouraud dextrose agar (SDA in tubes against P. digitatum and A. citri. The data were analyzed using one way analysis of variance (ANOVA using SPSS-17. Results The results indicate that extracts of A. marina mostly had been effective on P. digitatum and have the least impact on A. citri. The results show that the ethanol extract of mangrove leaf with antimicrobial activity method in 2 mg/mL, were inhibited the growth of P. digitatum and A. citri. In disk agar diffusion test the mentioned extract were shown inhibition effect on pathogen molds growth (P < 0.05. Conclusions Ethanolic extract compared to the aqueous extract was more effective and has a greater inhibition effect. The results of this study showed that the extract of A. marina has antifungal properties that justify their traditional use as medicinal plants.

  15. Transcription Factor Amr1 Induces Melanin Biosynthesis and Suppresses Virulence in Alternaria brassicicola

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yangrae; Srivastava, Akhil; Ohm, Robin A.; Lawrence, Christopher B.; Wang, Koon-Hui; Grigoriev, Igor V.; Marahatta, Sharadchandra P.

    2012-05-01

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. Several A. brassicicola genes have been characterized as affecting pathogenesis of Brassica species. To study regulatory mechanisms of pathogenesis, we mined 421 genes in silico encoding putative transcription factors in a machine-annotated, draft genome sequence of A. brassicicola. In this study, targeted gene disruption mutants for 117 of the transcription factor genes were produced and screened. Three of these genes were associated with pathogenesis. Disruption mutants of one gene (AbPacC) were nonpathogenic and another gene (AbVf8) caused lesions less than half the diameter of wild-type lesions. Unexpectedly, mutants of the third gene, Amr1, caused lesions with a two-fold larger diameter than the wild type and complementation mutants. Amr1 is a homolog of Cmr1, a transcription factor that regulates melanin biosynthesis in several fungi. We created gene deletion mutants of ?amr1 and characterized their phenotypes. The ?amr1 mutants used pectin as a carbon source more efficiently than the wild type, were melanin-deficient, and more sensitive to UV light and glucanase digestion. The AMR1 protein was localized in the nuclei of hyphae and in highly melanized conidia during the late stage of plant pathogenesis. RNA-seq analysis revealed that three genes in the melanin biosynthesis pathway, along with the deleted Amr1 gene, were expressed at low levels in the mutants. In contrast, many hydrolytic enzyme-coding genes were expressed at higher levels in the mutants than in the wild type during pathogenesis. The results of this study suggested that a gene important for survival in nature negatively affected virulence, probably by a less efficient use of plant cell-wall materials. We speculate that the functions of the Amr1 gene are important to the success of A. brassicicola as a competitive saprophyte and plant parasite.

  16. Expression analysis of chitinase upon challenge inoculation to Alternaria wounding and defense inducers in Brassica juncea

    Directory of Open Access Journals (Sweden)

    Sandhya Rawat

    2017-03-01

    Full Text Available Chitinases are the hydrolytic enzymes which belong to the pathogenesis-related (PR protein family and play an important role not only in plant defense but also in various abiotic stresses. However, only a limited number of chitinase genes have been characterised in B. juncea. In this study, we have characterised B. juncea class IV chitinase gene (accession no EF586206 in response to fungal infection, salicylic acid (SA, jasmonic acid (JA treatments and wounding. Gene expression studies revealed that the transcript levels of Bjchitinase (BjChp gene increases significantly both in local and distal tissues after Alternaria infection. Bjchitinase gene was also induced by jasmonic acid and wounding but moderately by salicylic acid. A 2.5 kb class IV chitinase promoter of this gene was isolated from B. juncea by Genome walking (accession no KF055403.1. In-silico analysis of this promoter revealed a number of conserved cis-regulatory elements related to defense, wounding and signalling molecules like SA, and JA. For validation, chitinase promoter was fused to the GUS gene, and the resultant construct was then introduced into Arabidopsis plants. Histochemical analysis of T2 transgenic Arabidopsis plants showed that higher GUS activity in leaves after fungal infection, wounding and JA treatment but weakly by SA. GUS activity was seen in meristematic tissues, young leaves, seeds and siliques. Finally investigation has led to the identification of a pathogen-inducible, developmentally regulated and organ-specific promoter. Present study revealed that Bjchitinase (BjChp promoter is induced during biotic and environmental stress and it can be used in developing finely tuned transgenics.

  17. Salicylic Acid Induces Resistance to Alternaria solani in Hydroponically Grown Tomato.

    Science.gov (United States)

    Spletzer, M E; Enyedi, A J

    1999-09-01

    ABSTRACT Alternaria solani is the causal agent of early blight disease in tomato and is responsible for significant economic losses sustained by tomato producers each year. Because salicylic acid (SA) is an important signal molecule that plays a critical role in plant defense against pathogen invasion, we investigated if the exogenous application of SA would activate systemic acquired resistance (SAR) against A. solani in tomato leaves. The addition of 200 muM SA to the root system significantly increased the endogenous SA content of leaves. Free SA levels increased 65-fold over basal levels to 5.85 mug g(-1) fresh weight (FW) after 48 h. This level of SA had no visible phytotoxic effects. Total SA content (free SA + SA-glucose conjugate) increased to 108 mug g(-1) FW after 48 h. Concomitant with elevated SA levels, expression of the tomato pathogenesis-related (PR)-1B gene was strongly induced within 24 h of the addition of 200 muM SA. PR-1B expression was still evident after 48 h; however, PR-1B induction was not observed in plants not receiving SA treatment. Challenge inoculation of SA-treated tomato plants using conidia of A. solani resulted in 83% fewer lesions per leaf and a 77% reduction in blighted leaf area as compared with control plants not receiving SA. Our data indicate that root feeding 200 muM SA to tomato plants can (i) significantly elevate foliar SA levels, (ii) induce PR-1B gene expression, and (iii) activate SAR that is effective against A. solani.

  18. Sensivity of Jordanian Isolates of Alternaria solani to Manchotane

    Directory of Open Access Journals (Sweden)

    K.I. Al-Mughrabi

    2004-04-01

    Full Text Available Early blight of potato, caused by Alternaria solani, poses a significant risk to potato crops worldwide. Fifty A. solani isolates representing a population were collected from the Jordan Valley, purified, and tested for their sensitivity to the fungicide mancothane. The isolates were tested against a series of concentrations of 0, 0.1, 1, 10, 100, and 1000 mg mancothane ml-1 in 5% sodium dodecyl sulfate (SDS. Some A. solani isolates tolerated up to 1000 mg mancothane ml-1. Isolates treated with the various concentrations were divided into 5 groups based on the percentage of A. solani growth achieved despite treatment: group 1 comprised isolates with mycelial growth of 0.1– 20.9%; group 2, 21–40.9%; group 3, 41–60.9%; group 4, 61–80.9%; and group 5, 81–100%. Ninety-seven percent of all isolates grew at 0.1 mg mancothane ml-1, 94% at 1 mg ml-1, 86% at 10 mg ml-1, 66% at 100 mg ml-1, and 16% at 1000 mg ml-1. Isolates appeared to be distributed normally at 10 mg mancothane ml-1. Eight isolates were highly resistant to mancothane and grew even at the highest test concentration. An A. solani population collected from potato fields in the Jordan Valley exhibited a moderate level of resistance to mancothane. Growers should be careful and vigilant when using this fungicide to control early blight.

  19. Effects of ozone on conidiophores and conidia of Alternaria solani

    Energy Technology Data Exchange (ETDEWEB)

    Rich, S.; Tomlinson, H.

    1968-04-01

    Ozone at 0.1 ppm for 4 hr or at 1.0 ppm for 2 hr stopped elongation of conidiophores of Alternaria solani, caused their apical cells to swell, and often collapsed the cell wall at their tips. These conidiophores began to elongate again when they were removed from ozone and exposed to light to prevent sporulation. Usually the collapsed end wall was sloughed, and the new cells often grew at an angle to the original axis of the conidiophore. Sometimes breaks appeared in the pigmented layers of the walls of the swollen cells. Ozone-damaged conidiophores, given the necessary dark period, sporulated normally. If sporulating cultures were exposed to 1.0 ppm ozone for 30 min, the conidia began to germinate while still attached to the conidiophores. Conidiophores treated with a subtoxic dose of a sulfhydryl-binding reagent (..cap alpha..-iodoacetamide) became more susceptible to ozone. Exposure to pure oxygen at either 1 or 4 atm pressure for 4 hr caused no visible damage to conidiophores of A. solani.

  20. Data on morphological features of mycosis induced by Colletotrichum nymphaeae and Lecanicillium longisporum on citrus orthezia scale

    Directory of Open Access Journals (Sweden)

    Gabriel Moura Mascarin

    2016-09-01

    Full Text Available We describe symptoms of mycosis induced by two native fungal entomopathogens of the citrus orthezia scale, Praelongorthezia praelonga (Hemiptera: Ortheziidae, an important pest of citrus orchards. The data presented in this article are related to the article entitled “Seasonal prevalence of the insect pathogenic fungus Colletotrichum nymphaeae in Brazilian citrus groves under different chemical pesticide regimes” [1]. The endemic fungal pathogen, C. nymphaeae, emerges through the thin cuticular intersegmental regions of the citrus orthezia scale body revealing orange salmon-pigmented conidiophores bearing conidial masses, as well as producing rhizoid-like hyphae that extend over the citrus leaf. By contrast, nymphs or adult females of this scale insect infected with Lecanicillium longisporum exhibit profuse outgrowth of bright white-pigmented conidiophores with clusters of conidia emerging from the insect intersegmental membranes, and mycosed cadavers are commonly observed attached to the leaf surface by hyphal extensions. These morphological differences are important features to discriminate these fungal entomopathogens in citrus orthezia scales.

  1. Effectivity of Kaffir lime (Citrus hystrix, Nasnaran Mandarin (Citrus amblycarpa, and Pomelo (Citrus maxima Leaf Extract Against Aedes aegypti Larvae

    Directory of Open Access Journals (Sweden)

    Hebert Adrianto

    2014-03-01

    Full Text Available The used of chemicals as larvicidal may causing resistance, health problem, and environment problem. Leaf extracts of Citrus as biolarvicidal against Aedes aegypti larvae can be used as an alternative larvicidal. The aims of this study is to find out the species of Citrus in the study sample, which is the most effective as biolarvicidal. This study was conducted using nested experiment design, with six treatments and five replicates. Larvae mortality was observed after 24 and 48 hours. Then, data were analyzed by probit. The results of this study show that (1 the LC95 value after 24 hours of exposure of leaf extracts of Citrus hystrix, Citrus amblycarpa, and Citrus maxima, were each 3,176 ppm; 4,174 ppm; and 6,369 ppm. (2 the LC95 value after 48 hours of exposure of leaf extracts of Citrus hystrix, Citrus amblycarpa, and Citrus maxima, were each 2,499 ppm; 3,256 ppm; and 4,886 ppm. (3 leaf extract of Citrus hystrix is the most effective among others as biolarvicidal against Aedes aegypti larvae. Leaf extract of Citrus hystrix can be used as alternative biolarvicidal.

  2. EXPLORATION OF SUITABLE SOLID MEDIA FOR MASS MULTIPLICATION OF Cochliobolus lunatus AND Alternaria alternata USED AS MYCOHERBICIDE FOR WEED MANAGEMENT (BARNYARD GRASS IN RICE

    Directory of Open Access Journals (Sweden)

    Jyothi G

    2013-09-01

    Full Text Available Fungal pathogens viz. Cochliobolus lunatus and Alternaria alternata were isolated from barnyard grass ( Echinochloa crusgalli and their pathogenicity was re - confirmed on same weed through various bioassays using spore suspension of both pathogens under green house conditi ons. For development of formulations of these mycoherbicide, large biomass is required and it is essential to find cheaper growth media to reduce the cost of the product. For this purpose, various solid substrates such as wheat and its bran, rice and its bran, broken sorghum and E. crusgalli seeds supplemented with yeast extract and molasses were used for mass multiplication of these weed pathogens. Among six substrates tested, rice supplemented with molasses (10g/L and yeast extract (3.0g/L produced high est conidia for both mycoherbicide after 14 days with 12h photoperiod at 25 0 C. The pathogenicity test with conidia obtained from both pathogens was conducted on 5 leaf stage of E. crusgalli and rice under glass house conditions. The results revealed that 100% mortality of the target weed within 14 days after treatment (DAT and no effect on rice.

  3. 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.

  4. 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.

  5. Antifungal Edible Coatings for Fresh Citrus Fruit: A Review

    Directory of Open Access Journals (Sweden)

    Lluís Palou

    2015-12-01

    Full Text Available According to their origin, major postharvest losses of citrus fruit are caused by weight loss, fungal diseases, physiological disorders, and quarantine pests. Cold storage and postharvest treatments with conventional chemical fungicides, synthetic waxes, or combinations of them are commonly used to minimize postharvest losses. However, the repeated application of these treatments has led to important problems such as health and environmental issues associated with fungicide residues or waxes containing ammoniacal compounds, or the proliferation of resistant pathogenic fungal strains. There is, therefore, an increasing need to find non-polluting alternatives to be used as part of integrated disease management (IDM programs for preservation of fresh citrus fruit. Among them, the development of novel natural edible films and coatings with antimicrobial properties is a technological challenge for the industry and a very active research field worldwide. Chitosan and other edible coatings formulated by adding antifungal agents to composite emulsions based on polysaccharides or proteins and lipids are reviewed in this article. The most important antifungal ingredients are selected for their ability to control major citrus postharvest diseases like green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, and include low-toxicity or natural chemicals such as food additives, generally recognized as safe (GRAS compounds, plant extracts, or essential oils, and biological control agents such as some antagonistic strains of yeasts or bacteria.

  6. Effect of irradiation as quarantine treatment on citrus fruit quality

    Energy Technology Data Exchange (ETDEWEB)

    Betancurt, Pablo; Montalban, Antonio; Arcia, Patricia; Borthagaray, Maria D.; Curutchet, Ana; Pica, Leticia; Soria, Alejandra; Abreu, Anibal V., E-mail: irradiacion@latu.org.u, E-mail: lacam@latu.org.u [Laboratorio Tecnologico del Uruguay (LATU), Montevideo (Uruguay); Ares, M. Ines, E-mail: mares@mgap.gub.u [Ministerio de Ganaderia, Agricultura y Pesca (MGAP), Montevideo (Uruguay). Directoria General de Sanidad Vegetal (DGSV)

    2009-07-01

    Gamma radiations have been used to improve sanitation treatments without significant effects on fresh fruit quality. The objective of this work was to evaluate the fruit quality characteristics of citrus variety Valencia (Valencia Late), main variety produced and exported in Uruguay. All samples were stored at 3-5 deg C, 80% RH, for 20 and 40 days. Irradiation doses used were 0,35 kGy min. and 0,80 kGy max. (doses that also eliminate the fruit fly). Irradiation experiments were conducted using irradiation equipment from Atomic Center (CAE), year 1968, Co60 source, 800.000 Ci. The effects of irradiation on sensory qualities and physical characteristics were studied. The attributes evaluated were visual appearance (1- 4 hedonic scale, expert), overall acceptance (1-9 hedonic scale, consumers), texture (TAB Stevens, speed: 2m/s, distance: 2mm), yield of juice and colour (Hunter values). In general, no significant changes in these parameters were observed after irradiation. Quality was not significantly affected by doses usually applied to decrease the viability of pathogen that cause citrus Scab. This is an important contribution for the protocols that would allow citrus fruit exportation. (author)

  7. 'Wuzishatangju' mandarin (Citrus reticulata Blanco)

    African Journals Online (AJOL)

    ARL4

    African Journal of Biotechnology Vol. 11(89), pp. ... increased to meet the challenge of process industry and particular consumer ... biotechnology, the advent of molecular markers has made it ..... Innovation and Utilization for Germplasm Resources in ... Construction of DNA fingerprinting database of citrus cultivars. (Lines).

  8. A compatible interaction of Alternaria brassicicola with Arabidopsis thaliana ecotype DiG: evidence for a specific transcriptional signature

    Directory of Open Access Journals (Sweden)

    Gepstein Shimon

    2009-03-01

    Full Text Available Abstract Background The interaction of Arabidopsis with Alternaria brassicicola provides a model for disease caused by necrotrophs, but a drawback has been the lack of a compatible pathosystem. Infection of most ecotypes, including the widely-studied line Col-0, with this pathogen generally leads to a lesion that does not expand beyond the inoculated area. This study examines an ecotype, Dijon G (DiG, which is considered sensitive to A. brassicicola. Results We show that the interaction has the characteristics of a compatible one, with expanding rather than limited lesions. To ask whether DiG is merely more sensitive to the pathogen or, rather, interacts in distinct manner, we identified genes whose regulation differs between Col-0 and DiG challenged with A. brassicicola. Suppression subtractive hybridization was used to identify differentially expressed genes, and their expression was verified using semi-quantitative PCR. We also tested a set of known defense-related genes for differential regulation in the two plant-pathogen interactions. Several known pathogenesis-related (PR genes are up-regulated in both interactions. PR1, and a monooxygenase gene identified in this study, MO1, are preferentially up-regulated in the compatible interaction. In contrast, GLIP1, which encodes a secreted lipase, and DIOX1, a pathogen-response related dioxygenase, are preferentially up-regulated in the incompatible interaction. Conclusion The results show that DiG is not only more susceptible, but demonstrate that its interaction with A. brassicicola has a specific transcriptional signature.

  9. Novel diagnosis for citrus stubborn disease by detection of a spiroplasma citri-secreted protein.

    Science.gov (United States)

    Shi, Jinxia; Pagliaccia, Deborah; Morgan, Robyn; Qiao, Yongli; Pan, Songqin; Vidalakis, Georgios; Ma, Wenbo

    2014-02-01

    Citrus stubborn disease (CSD), first identified in California, is a widespread bacterial disease found in most arid citrus-producing regions in the United States and the Mediterranean Region. The disease is caused by Spiroplasma citri, an insect-transmitted and phloem-colonizing bacterium. CSD causes significant tree damage resulting in loss of fruit production and quality. Detection of CSD is challenging due to low and fluctuating titer and sporadic distribution of the pathogen in infected trees. In this study, we report the development of a novel diagnostic method for CSD using an S. citri-secreted protein as the detection marker. Microbial pathogens secrete a variety of proteins during infection that can potentially disperse systemically in infected plants with the vascular flow. Therefore, their distribution may not be restricted to the pathogen infection sites and could be used as a biological marker for infection. Using mass spectrometry analysis, we identified a unique secreted protein from S. citri that is highly expressed in the presence of citrus phloem extract. ScCCPP1, an antibody generated against this protein, was able to distinguish S. citri-infected citrus and periwinkle from healthy plants. In addition, the antiserum could be used to detect CSD using a simple direct tissue print assay without the need for sample processing or specialized lab equipment and may be suitable for field surveys. This study provides proof of a novel concept of using pathogen-secreted protein as a marker for diagnosis of a citrus bacterial disease and can probably be applied to other plant diseases.

  10. First report of QoI resistance in Alternaria spp. infecting sugar beet (Beta vulgaris) in Michigan, USA

    Science.gov (United States)

    Alternaria leaf spot (ALS) of sugar beet is caused by Alternaria spp. in the A. alternata species complex. ALS is common wherever sugar beet is grown, but historically has been a minor issue for sugar beet production in the USA with damage usually not affecting crop yield significantly. Occurrence o...

  11. Synergistic estrogenic effects of Fusarium and Alternaria mycotoxins in vitro.

    Science.gov (United States)

    Vejdovszky, Katharina; Hahn, Kathrin; Braun, Dominik; Warth, Benedikt; Marko, Doris

    2017-03-01

    Mycotoxins are toxic secondary metabolites formed by various fungal species that are found as natural contaminants in food. This very heterogeneous group of compounds triggers multiple toxic mechanisms, including endocrine disruptive potential. Current risk assessment of mycotoxins, as for most chemical substances, is based on the effects of single compounds. However, concern on a potential enhancement of risks by interactions of single substances in naturally occurring mixtures has greatly increased recently. In this study, the combinatory effects of three mycoestrogens were investigated in detail. This includes the endocrine disruptors zearalenone (ZEN) and α-zearalenol (α-ZEL) produced by Fusarium fungi and alternariol (AOH), a cytotoxic and estrogenic mycotoxin formed by Alternaria species. For evaluation of effects, estrogen-dependent activation of alkaline phosphatase (AlP) and cell proliferation were tested in the adenocarcinoma cell line Ishikawa. The estrogenic potential varied among the single substances. Half maximum effect concentrations (EC50) for AlP activation were evaluated for α-ZEL, ZEN and AOH as 37 pM, 562 pM and 995 nM, respectively. All three mycotoxins were found to act as partial agonists. The majority of binary combinations, even at very low concentrations in the case of α-ZEL, showed strong synergism in the AlP assay. These potentiating phenomena of mycotoxin mixtures highlight the urgent need to incorporate combinatory effects into future risk assessment, especially when endocrine disruptors are involved. To the best of our knowledge, this study presents the first investigation on synergistic effects of mycoestrogens.

  12. PENDIDIKAN DAN PELATIHAN PEMBIBITAN JERUK BEBAS PENYAKIT CVPD (Citrus Vein Phloem Degeneration DI DESA KATUNG KINTAMANI

    Directory of Open Access Journals (Sweden)

    Adiartayasa W

    2012-10-01

    Full Text Available The community service in the form of training about free orange seed of disease CVPD (Citrus Vein Phloem Degenaration was conducted in Katung village, district of Kintamani, Bangli regency on 10 August 2007. The training activity aimed to improve knowledge of farmers about CVPD disease, symptom, transmission, insect vector, and integrated pest management. The topics covered were disease symptoms, and pathogen bacteria, Diaphorina citri are as insect vector infection mechanism, election of free orange mains crops CVPD, disease distribution and integrated management of CVPD. The training was attended by 25 participants from local groups of Katung village. The methods used in this activity were lectures, demonstration and practical work in the citrus field. All participants enthusiastically took part and hoped to have the next intensive training of citrus culture.

  13. TENACITY AND PERSISTENCE OF COPPER FUNGICIDES IN CITRUS SEEDLINGS UNDER SIMULATED RAINFALL

    Directory of Open Access Journals (Sweden)

    ANTONIO EDUARDO FONSECA

    2016-01-01

    Full Text Available The amount of fungicide that adheres to the leaf during spraying and the amount that remain on the leaf after weathering are the main factors that defines the amount of active residue on the leaf surface to effectively control plant pathogens. Thus, the objective of this work was to evaluate the tenacity and persistence of copper in citrus seedling leaves under simulated rainfall in Jaboticabal, State of São Paulo, Brazil. The evaluated variables were copper content, solution retention, surface tension and drop spectrum. A significant and inversely proportional linear relationship to drops <100 μm was found. The percentage of copper retained in leaves of citrus seedlings with copper fungicides of suspension concentrate (SC formulations after simulated rainfall was greater than 80%. Copper fungicides of SC formulations presented the lowest surface tension, allowing greater tenacity and persistence of copper on seedlings of citrus leaves after simulated rainfall and increased contact between the drops and leaf surface.

  14. Alternaria alternata prevalence in cereal grains and soybean seeds from Entre Ríos, Argentina.

    Science.gov (United States)

    Broggi, Leticia Elvira; González, Héctor Horacio Lucas; Resnik, Silvia Liliana; Pacin, Ana

    2007-03-01

    A mycological survey was carried out at Entre Ríos province, Argentina, on sorghum grain, maize, rice, soybean seeds and on freshly harvested and stored wheat. The isolation frequencies and relative densities of species belonging to genera Alternaria, Aspergillus, Fusarium, Penicillium and other fungi were calculated. Alternaria alternata was the major fungal species isolated from sorghum, rice, soybean seeds and on freshly harvested wheat, and a low incidence of Fusarium species was observed on the same substrates. In maize the major fungal species isolated was Fusarium verticillioides. The high incidence levels of A. alternata observed,suggest that it may be necessary to determine, among other mycotoxins, if Alternaria toxins occur in these commodities.

  15. Cutaneous infection with Alternaria triticina in a Bilateral lung transplant recipient.

    Science.gov (United States)

    González-Vela, M C; Armesto, S; Unda-Villafuerte, F; Val-Bernal, J F

    2014-10-01

    We report the case of a 60-year-old man who was receiving immunosuppressive therapy for a bilateral lung transplant and presented with a crusted, violaceous plaque on the left hand. Based on histopathology and microbiological culture the patient was diagnosed with infection by Alternaria species. Treatment with itraconazole led to complete resolution of the skin lesion. Forty months later he developed four reddish, nodular, skin lesions on the left leg. Analysis of a biopsy from one of these lesions using histopathologic and molecular techniques identified a mold that shared 98% homology with a strain of Alternaria triticina. Alternaria species belong to a group of dematiaceous fungi that cause opportunistic infections in humans. The incidence of these infections is increasing, mainly in transplant centers. To the best of our knowledge, this is the first reported case of a human infection caused by A. triticina. Copyright © 2013 Elsevier España, S.L.U. and AEDV. All rights reserved.

  16. Alternaria and Fusarium in Norwegian grains of reduced quality - a matched pair sample study

    DEFF Research Database (Denmark)

    Kosiak, B.; Torp, M.; Skjerve, E.;

    2004-01-01

    The occurrence and geographic distribution of species belonging to the genera Alternaria and Fusarium in grains of reduced and of acceptable quality were studied post-harvest in 1997 and 1998. A total of 260 grain samples of wheat, barley and oats was analysed. The distribution of Alternaria...... and Fusarium spp. varied significantly in samples of reduced quality compared with acceptable samples. Alternaria spp. dominated in the acceptable samples with A. infectoria group as the most frequently isolated and most abundant species group of this genus while Fusarium spp. dominated in samples of reduced...... quality. The most frequently isolated Fusarium spp. from all samples were F avenaceum, E poae, F culmorum and E tricinctum. Other important toxigenic Fusarium spp. isolated were F graminearum and E equiseti. The infection levels of F graminearum and F culmorunt were significantly higher in the samples...

  17. Identification of Alternaria isolates from America soybean%美国大豆中链格孢的分离鉴定研究

    Institute of Scientific and Technical Information of China (English)

    冉俊祥; 肖杰文; 杨占臣; 刘月廉

    2011-01-01

    本文通过对美国进境大豆病害分离,共得到36个菌株,并对其中5株链格孢菌进行了形态学和分子生物学鉴定(其中2株),确认了它们分别是细极链格孢(Alternaria tenuissima(Kunze)Wiltshire)、樱桃链格孢(Alternaria cerasi Potebnia)、苘麻链格孢(Alternaria abutilonis(Speg.).Schwarze)、百日菊链格孢(Alternaria zinniae H.Pape)、落葵链格孢(Alternaria basellae T.Y.Zhang).本研究证实了美国大豆中链格孢菌的多样性,不仅充实了正在构建的大豆病害数据库和菌种资源库,也可为港口的植物检疫工作提供借鉴.%In this article, 36 separate strains from America soybean were obtained, and five Alternaria isolates were identified by morphological and molecular biology method, which are Alternaria tenuissima (Kunze) Wiltshire, Alternaria cerasi Potebnia, Alternaria abutilonis ( Speg. ) Schwarze, Alternaria zinniae H. Pape and Alternaria basellae T. Y. Zhang, respectively. It proved that Alternaria had rich diversity in America soybean , and it can not only enrich the soybean databank and strain resource , but also provide reference for plant quarantine.

  18. Development of rapid, sensitive and non-radioactive tissue-blot diagnostic method for the detection of citrus greening.

    Science.gov (United States)

    Nageswara-Rao, Madhugiri; Miyata, Shin-Ichi; Ghosh, Dilip; Irey, Mike; Garnsey, Stephen M; Gowda, Siddarame

    2013-01-01

    Citrus huanglongbing (HLB or citrus greening) is one of the most devastating diseases of citrus worldwide. The disease is caused by Gram-negative, phloem-limited α-proteobacterium, 'Candidatus Liberibacter asiaticus', vectored by the psyllid, Diaphorina citri Kuwayama. Citrus plants infected by the HLB bacterium may not show visible symptoms sometimes for years following infection and non-uniform distribution within the tree makes the detection of the pathogen very difficult. Efficient management of HLB disease requires rapid and sensitive detection early in the infection followed by eradication of the source of pathogen and the vector. The polymerase chain reaction (PCR) based method is most commonly employed for screening the infected/suspected HLB plants and psyllids. This is time consuming, cumbersome and not practical for screening large number of samples in the field. To overcome this, we developed a simple, sensitive, non-radioactive, tissue-blot diagnostic method for early detection and screening of HLB disease. Digoxigenin labeled molecular probes specific to 'Ca. L. asiaticus' nucleotide sequences have been developed and used for the detection of the pathogen of the HLB disease. The copy number of the target genes was also assessed using real-time PCR experiments and the optimized real-time PCR protocol allowed positive 'Ca. L. asiaticus' detection in citrus samples infected with 'Ca. L. asiaticus' bacterium.

  19. Thymus vulgaris essential oil and thymol against Alternaria alternata (Fr.) Keissler: effects on growth, viability, early infection and cellular mode of action.

    Science.gov (United States)

    Perina, Fabiano J; Amaral, Douglas C; Fernandes, Rafael S; Labory, Claudia Rg; Teixeira, Glauco A; Alves, Eduardo

    2015-10-01

    In initial assays, Thymus vulgaris essential oil (TEO) has demonstrated activity against several plant-pathogenic fungi and has reduced the fungal diseases to levels comparable with commercial fungicides. Thus, the goal of this work was to identify the mode of action in fungi of TEO and its major compound thymol (TOH) at the cellular level using an ultrastructure approach. TEO from leaves and TOH had minimum inhibitory concentrations (MICs) of 500 and 250 µg mL(-1) respectively against A. alternata; under the same conditions, MIC for a commercial fungicide was 1250 µg mL(-1) . Ultrastructure analysis showed that TOH phenolic substance prevented fungal growth, reduced fungal viability and prevented the penetration in fruits by a cell wall/plasma membrane interference mode of action with organelles targeted for destruction in the cytoplasm. Such mode of action differs from protective and preventive-curative commercial fungicides used as pattern control. These findings suggest that TOH was responsible for the antifungal activity of TEO. Therefore, both the essential oil and its major substance have potential for use in the development of new phenolic structures and analogues to control Alternaria brown spot disease caused by Alternaria alternata. © 2014 Society of Chemical Industry.

  20. Development of a Semi-nested PCR-Based Method for Specific and Rapid Detection of Alternaria solani Causing Potato Early Blight in Soil.

    Science.gov (United States)

    Gu, Qing; Yang, Zhi-Hui; Zhao, Dong-Mei; Zhang, Dai; Wang, Qian; Ma, Li-Song; Zhu, Jie-Hua

    2017-09-01

    Early blight, caused by Alternaria solani, is one of the most devastating diseases of potato that causes severe yield loss worldwide. The infected potato debris existed in the soil serve as the initial infection sources for the next growing potato. Current identification of A. solani in soil relies primarily on cultural and morphological characteristics, which are time-consuming and inaccurate. In this study, a semi-nested PCR method was developed using primers based on internal transcribed spacer region that is specific to A. solani. 20 isolates including 6 Alternaria species and 10 other species of common potato pathogens were used to examine the specificity of the primers. The primer set ptAsQ-F/ptAs-R was highly specific to A. solani, as a product of 251 bp was amplified only from A. solani isolates and no amplification signal was observed from other tested species. The sensitivity of this method determined using A. solani genomic DNA was 10 fg. This PCR assay was also successfully employed to detect A. solani in soil with the detection sensitivity of one conidia spore in 0.5 g of soil. To the best of our knowledge, this is the first report of molecular detection of A. solani in soil, which provides a useful tool for early and rapid detection of early blight in soil before next growing season.

  1. Field ID guide to citrus relative hosts of Asian citrus psyllid & Huanglongbing

    Science.gov (United States)

    The Rutaceae family of plants includes not only species within the genus Citrus, but also several other genera and species that may not be easily recognized as having any relationship to citrus at all. However, many of these citrus relatives are used for ornamental, culinary, or religious purposes. ...

  2. 78 FR 63369 - Citrus Canker, Citrus Greening, and Asian Citrus Psyllid; Interstate Movement of Regulated...

    Science.gov (United States)

    2013-10-24

    ... infected plants, which render the fruit unmarketable, and cause infected fruit to drop from the trees... of the fruit, and can kill trees. Once infected, there is no cure for a tree with citrus greening. In... disease that is caused by a complex of Xanthomonas spp. bacteria and that affects plants and plant...

  3. Possible role of plant volatiles in tolerance against huanglongbing in citrus.

    Science.gov (United States)

    Hijaz, Faraj; Nehela, Yasser; Killiny, Nabil

    2016-01-01

    Volatile organic compounds (VOC) play an important role in protecting plants from insect and pathogen attack. In this study, we investigated the leaf volatile profiles of 14 citrus varieties. The VOC in citrus leaves were extracted with n-hexane and analyzed using gas chromatography-mass spectrometry (GC-MS). Overall, 4six volatile compounds were identified in the n-hexane extract from citrus leaves. Most of the detected compounds belonged to 3 main groups (monoterpenes, sesquiterpenes, and aliphatic aldehydes). Principle component analysis was used to examine the relative distribution of the studied varieties to each other. Interestingly, volatile profiles of varieties that are tolerant to Candidatus Liberibacter asiaticus (CLas) were different from those of the susceptible ones. Tolerant and moderately-tolerant cultivars contained relatively higher amounts of volatiles than susceptible varieties. In addition, tolerant varieties were also higher in specific compounds which are known for their antimicrobial activities. These compounds include Aldehydes (undecanal, neral, geranial, and citronellal) and some monoterpenes such as linalool, d-limonene, myrcene, α- and β- phellandrene. In addition, some sesquiterpene compounds including t-caryophellene, γ-elemene, β-elemene, germacrene D, and geranyl acetate were higher in tolerant and moderately tolerant cultivars. Severinia buxifolia which is known for its tolerance to CLas and many other pathogens contained higher levels of santalenes and coumarins. Our results indicated that citrus leaf volatiles might play a role in citrus tolerance to CLas. The results of this study may help in understanding of the mechanism of citrus tolerance against CLas.

  4. Genome editing of the disease susceptibility gene CsLOB1 in citrus confers resistance to citrus canker.

    Science.gov (United States)

    Jia, Hongge; Zhang, Yunzeng; Orbović, Vladimir; Xu, Jin; White, Frank F; Jones, Jeffrey B; Wang, Nian

    2017-07-01

    Citrus is a highly valued tree crop worldwide, while, at the same time, citrus production faces many biotic challenges, including bacterial canker and Huanglongbing (HLB). Breeding for disease-resistant varieties is the most efficient and sustainable approach to control plant diseases. Traditional breeding of citrus varieties is challenging due to multiple limitations, including polyploidy, polyembryony, extended juvenility and long crossing cycles. Targeted genome editing technology has the potential to shorten varietal development for some traits, including disease resistance. Here, we used CRISPR/Cas9/sgRNA technology to modify the canker susceptibility gene CsLOB1 in Duncan grapefruit. Six independent lines, DLOB 2, DLOB 3, DLOB 9, DLOB 10, DLOB 11 and DLOB 12, were generated. Targeted next-generation sequencing of the six lines showed the mutation rate was 31.58%, 23.80%, 89.36%, 88.79%, 46.91% and 51.12% for DLOB 2, DLOB 3, DLOB 9, DLOB 10, DLOB 11 and DLOB 12, respectively, of the cells in each line. DLOB 2 and DLOB 3 showed canker symptoms similar to wild-type grapefruit, when inoculated with the pathogen Xanthomonas citri subsp. citri (Xcc). No canker symptoms were observed on DLOB 9, DLOB 10, DLOB 11 and DLOB 12 at 4 days postinoculation (DPI) with Xcc. Pustules caused by Xcc were observed on DLOB 9, DLOB 10, DLOB 11 and DLOB 12 in later stages, which were much reduced compared to that on wild-type grapefruit. The pustules on DLOB 9 and DLOB 10 did not develop into typical canker symptoms. No side effects and off-target mutations were detected in the mutated plants. This study indicates that genome editing using CRISPR technology will provide a promising pathway to generate disease-resistant citrus varieties. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  5. Development of a full-genome cDNA clone of Citrus leaf blotch virus and infection of citrus plants.

    Science.gov (United States)

    Vives, María Carmen; Martín, Susana; Ambrós, Silvia; Renovell, Agueda; Navarro, Luis; Pina, Jose Antonio; Moreno, Pedro; Guerri, José

    2008-11-01

    Citrus leaf blotch virus (CLBV), a member of the family Flexiviridae, has a ~9-kb single-stranded, positive-sense genomic RNA encapsidated by a 41-kDa coat protein. CLBV isolates are associated with symptom production in citrus including leaf blotching of Dweet tangor and stem pitting in Etrog citron (Dweet mottle disease), and some isolates are associated with bud union crease on trifoliate rootstocks, but Koch's postulates for this virus were not fulfilled. A full-genome cDNA of CLBV isolate SRA-153, which induces bud union crease, was placed under the T7 promoter (clone T7-CLBV), or between the 35S promoter and the Nos-t terminator, with or without a ribozyme sequence downstream of the CLBV sequence (clones 35SRbz-CLBV and 35S-CLBV). RNA transcripts from T7-CLBV failed to infect Etrog citron and Nicotiana occidentalis and N. benthamiana plants, whereas agro-inoculation with binary vectors carrying 35SRbz-CLBV or 35S-CLBV, and the p19 silencing suppressor, caused systemic infection and production of normal CLBV virions. Virus accumulation was similar in citron plants directly agro-infiltrated, or mechanically inoculated with wild-type or 35SRbz-CLBV-derived virions from Nicotiana, and the three sources incited the symptoms characteristic of Dweet mottle disease, but not bud union crease. Our results show that (1) virions derived from an infectious clone show the same replication, movement and pathogenicity characteristics as the wild-type CLBV; (2) CLBV is the causal agent of Dweet mottle disease but not of the bud union crease syndrome; and (3) for the first time an RNA virus could be successfully agro-inoculated on citrus plants. This infectious clone may become a useful viral vector for citrus genomic studies.

  6. Asian citrus psyllid RNAi pathway : RNAi evidence

    OpenAIRE

    Taning, Clauvis N. T.; Andrade, Eduardo C.; Hunter, Wayne B.; Olivier Christiaens; Guy Smagghe

    2016-01-01

    Diaphorina citri, known as the Asian citrus psyllid, is an important pest of citrus because it transmits a phloem-limited bacteria strongly implicated in huanglongbing (citrus greening disease). Emerging biotechnologies, such as RNA interference, could provide a new sustainable and environmentally friendly strategy for the management of this pest. In this study, genome and functional analysis were performed to verify whether the RNAi core genes are present in the Asian psyllid genome and if t...

  7. Citrus allergy from pollen to clinical symptoms.

    Directory of Open Access Journals (Sweden)

    Rosa Anna Iorio

    Full Text Available Allergy to citrus fruits is often associated with pollinosis and sensitization to other plants due to a phenomenon of cross-reactivity. The aims of the present study were to highlight the cross-reactivity among citrus and the major allergenic pollens/fruits, throughout clinical and molecular investigations, and to evaluate the sensitization frequency to citrus fruits in a population of children and adults with pollinosis. We found a relevant percentage of sensitisation (39% to citrus fruits in the patients recruited and in all of them the IgE-mediated mechanism has been confirmed by the positive response to the prick-to-prick test. RT-PCR experiments showed the expression of Cit s 1, Cit s 3 and a profilin isoform, already described in apple, also in Citrus clementine pollen. Data of multiple sequence alignments demonstrated that Citrus allergens shared high percentage identity values with other clinically relevant species (i.e. Triticum aestivum, Malus domestica, confirming the possible cross-allergenicity citrus/grasses and citrus/apple. Finally, a novelty of the present work has been the expression of two phospholipaseA2 isoforms (PLA2 α and β in Citrus as well as in Triticum pollens; being PLA2 able to generate pro-inflammatory factors, this enzyme could participate in the activation of the allergenic inflammatory cascade.

  8. Priming by Hexanoic Acid Induce Activation of Mevalonic and Linolenic Pathways and Promotes the Emission of Plant Volatiles

    OpenAIRE

    Eugenio eLlorens; Gemma eCamañes; Leonor eLapeña; Pilar eGarcía-Agustín

    2016-01-01

    Hexanoic acid is a short natural monocarboxylic acid present in some fruits and plants. Previous studies reported that soil drench application of this acid induces effective resistance in tomato plants against Botrytis cinerea and Pseudomonas syringae and in citrus against Alternaria alternata and Xanthomonas citri. In this work, we performed an in deep study of the metabolic changes produced in citrus by the application of hexanoic acid in response to the challenge pathogen Alternaria altern...

  9. Huanglongbing, a systemic disease, restructures the bacterial community associated with citrus roots.

    Science.gov (United States)

    Trivedi, Pankaj; Duan, Yongping; Wang, Nian

    2010-06-01

    To examine the effect of pathogens on the diversity and structure of plant-associated bacterial communities, we carried out a molecular analysis using citrus and huanglongbing as a host-disease model. 16S rRNA gene clone library analysis of citrus roots revealed shifts in microbial diversity in response to pathogen infection. The clone library of the uninfected root samples has a majority of phylotypes showing similarity to well-known plant growth-promoting bacteria, including Caulobacter, Burkholderia, Lysobacter, Pantoea, Pseudomonas, Stenotrophomonas, Bacillus, and Paenibacillus. Infection by "Candidatus Liberibacter asiaticus" restructured the native microbial community associated with citrus roots and led to the loss of detection of most phylotypes while promoting the growth of bacteria such as Methylobacterium and Sphingobacterium. In pairwise comparisons, the clone library from uninfected roots contained significantly higher 16S rRNA gene diversity, as reflected in the higher Chao 1 richness estimation (P pathogen. These data indicate that infection of citrus by "Ca. Liberibacter asiaticus" has a profound effect on the structure and composition of the bacterial community associated with citrus roots.

  10. Comparison of FTIR spectra between Huanglongbing (citrus greening) and other citrus maladies.

    Science.gov (United States)

    Hawkins, Samantha A; Park, Bosoon; Poole, Gavin H; Gottwald, Tim R; Windham, William R; Albano, Joseph; Lawrence, Kurt C

    2010-05-26

    Fourier transform infrared (FTIR) spectroscopy has the ability to quickly identify the presence of specific carbohydrates in plant materials. The presence of the disease huanglongbing (HLB) in the leaves of infected citrus plants has a distinctive spectrum that can be used to distinguish an infected plant from a healthy plant. However, many citrus diseases display similar visible symptoms and are of concern to citrus growers. In this study several citrus diseases (citrus leaf rugose virus, citrus tristeza virus, citrus psorosis virus, and Xanthomonas axonopodis ) and nutrient deficiencies (iron, copper, zinc, manganese, and magnesium) were compared with HLB using FTIR spectroscopy to determine if the spectra alone can be used to identify plants that are infected with HLB instead of another disease. The results indicate that the spectra of some diseases and deficiencies more closely resemble those of apparently healthy plants and some share the carbohydrate transformation that has been seen in the spectra of HLB-infected plants.

  11. Green synthesis of gold nanoparticles using Citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) aqueous extract and its characterization.

    Science.gov (United States)

    Sujitha, Mohanan V; Kannan, Soundarapandian

    2013-02-01

    This study reports the biological synthesis of gold nanoparticles by the reduction of HAuCl(4) by using citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) juice extract as the reducing and stabilizing agent. A various shape and size of gold nanoparticles were formed when the ratio of the reactants were altered with respect to 1.0mM chloroauric acid solution. The gold nanoparticles obtained were characterized by UV-visible spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM studies showed the particles to be of various shapes and sizes and particle size ranges from 15 to 80 nm. Selected-area electron diffraction (SAED) pattern confirmed fcc phase and crystallinity of the particles. The X-ray diffraction analysis revealed the distinctive facets (111, 200, 220 and 222 planes) of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size for colloid gp(3) of C. limon, C. reticulata and C. sinensis are 32.2 nm, 43.4 nm and 56.7 nm respectively. The DLS graph showed that the particles size was larger and more polydispersed compared to the one observed by TEM due to the fact that the measured size also includes the bio-organic compounds enveloping the core of the Au NPs. Zeta potential value for gold nanoparticles obtained from colloid gp(3) of C. limon, C. reticulata and C. sinensis are -45.9, -37.9 and -31.4 respectively indicating the stability of the synthesized nanoparticles. Herein we propose a novel, previously unexploited method for the biological syntheses of polymorphic gold nanoparticles with potent biological applications.

  12. Green synthesis of gold nanoparticles using Citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) aqueous extract and its characterization

    Science.gov (United States)

    Sujitha, Mohanan V.; Kannan, Soundarapandian

    2013-02-01

    This study reports the biological synthesis of gold nanoparticles by the reduction of HAuCl4 by using citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) juice extract as the reducing and stabilizing agent. A various shape and size of gold nanoparticles were formed when the ratio of the reactants were altered with respect to 1.0 mM chloroauric acid solution. The gold nanoparticles obtained were characterized by UV-visible spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM studies showed the particles to be of various shapes and sizes and particle size ranges from 15 to 80 nm. Selected-area electron diffraction (SAED) pattern confirmed fcc phase and crystallinity of the particles. The X-ray diffraction analysis revealed the distinctive facets (1 1 1, 2 0 0, 2 2 0 and 2 2 2 planes) of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size for colloid gp3 of C. limon, C. reticulata and C. sinensis are 32.2 nm, 43.4 nm and 56.7 nm respectively. The DLS graph showed that the particles size was larger and more polydispersed compared to the one observed by TEM due to the fact that the measured size also includes the bio-organic compounds enveloping the core of the Au NPs. Zeta potential value for gold nanoparticles obtained from colloid gp3 of C. limon, C. reticulata and C. sinensis are -45.9, -37.9 and -31.4 respectively indicating the stability of the synthesized nanoparticles. Herein we propose a novel, previously unexploited method for the biological syntheses of polymorphic gold nanoparticles with potent biological applications.

  13. Transcriptome analysis of root response to citrus blight based on the newly assembled Swingle citrumelo draft genome.

    Science.gov (United States)

    Zhang, Yunzeng; Barthe, Gary; Grosser, Jude W; Wang, Nian

    2016-07-08

    Citrus blight is a citrus tree overall decline disease and causes serious losses in the citrus industry worldwide. Although it was described more than one hundred years ago, its causal agent remains unknown and its pathophysiology is not well determined, which hampers our understanding of the disease and design of suitable disease management. In this study, we sequenced and assembled the draft genome for Swingle citrumelo, one important citrus rootstock. The draft genome is approximately 280 Mb, which covers 74 % of the estimated Swingle citrumelo genome and the average coverage is around 15X. The draft genome of Swingle citrumelo enabled us to conduct transcriptome analysis of roots of blight and healthy Swingle citrumelo using RNA-seq. The RNA-seq was reliable as evidenced by the high consistence of RNA-seq analysis and quantitative reverse transcription PCR results (R(2) = 0.966). Comparison of the gene expression profiles between blight and healthy root samples revealed the molecular mechanism underneath the characteristic blight phenotypes including decline, starch accumulation, and drought stress. The JA and ET biosynthesis and signaling pathways showed decreased transcript abundance, whereas SA-mediated defense-related genes showed increased transcript abundance in blight trees, suggesting unclassified biotrophic pathogen was involved in this disease. Overall, the Swingle citrumelo draft genome generated in this study will advance our understanding of plant biology and contribute to the citrus breeding. Transcriptome analysis of blight and healthy trees deepened our understanding of the pathophysiology of citrus blight.

  14. A rare case of allergic bronchopulmonary mycosis caused by Alternaria alternata.

    NARCIS (Netherlands)

    Chowdhary, A.; Agarwal, K.; Randhawa, H.S.; Kathuria, S.; Gaur, S.N.; Najafzadeh, M.J.; Roy, P.; Arora, N.; Khanna, G.; Meis, J.F.G.M.

    2012-01-01

    A rare case of allergic bronchopulmonary mycosis (ABPM), caused by Alternaria alternata, is reported in an immunocompetent resident of Delhi. Her complaints included a generalized, urticarial skin rash and occasional pain in the right lower chest. Her differential count showed eosinophils, 22%; abso

  15. Potato carrot agar with manganese as an isolation medium for Alternaria, Epicoccum and Phoma

    DEFF Research Database (Denmark)

    Sørensen, Jens Laurids; Mogensen, Jesper Mølgaard; Thrane, Ulf

    2009-01-01

    A semi-selective medium for isolation of Alternaria spp., Epicoccum sp. and Phoma spp. from soil and plant samples was developed. The basal medium was a modified potato carrot agar (PCA), containing 10 g/L of potato and carrot. It is known that the target genera sporulate well on standard PCA whe...

  16. Meteorological and agricultural effects on airborne Alternaria and Cladosporium spores and clinical aspects in Valladolid (Spain).

    Science.gov (United States)

    Reyes, Estefanía Sánchez; de la Cruz, David Rodríguez; Merino, Ma Eugenia Sanchís; Sánchez, José Sánchez

    2009-01-01

    The aeropalynological monitoring was carried out from 1 February 2005-31 January 2007. The total number of spores collected during the main spore season (MSS) in 2005 was 4,500 for Alternaria and 93,744 in the case of Cladosporium, whereas in 2006 values were increased (8,385 for Alternaria and 150,144 for Cladosporium), reaching the maximum concentrations on 18 July and 17 June 2006 with 344 and 5,503 spores, respectively. The influence of the main meteorological parameters on spore concentrations was studied, resulting in a positive correlation with temperature. Rainfall, relative humidity and frequency of calms obtained negative correlations in the case of Alternaria, and positive for Cladosporium, the total daily hours of sunshine having an inverse influence on them. The intra-diurnal pattern was very similar for both genera, with a greater representation towards the central hours of the day and at night. Finally, some clinical aspects for the Alternaria spore type were analyzed, with a low percentage of sensitized patients though (9.5%). Only one patient showed positive skin test reaction to Cladosporium.

  17. Alternaria fungal dermatitis in a free-ranging javelina (Pecari tajacu).

    Science.gov (United States)

    Shender, Lisa A; Gerhold, Rick; Sanchez, Susan; Keel, M Kevin

    2011-07-01

    We report a javelina from Pinal County, Arizona, USA, with severe fungal dermatitis and cellulitis. Extreme emaciation and rostral disfiguration, including left-lateral displacement of the nasal planum, justified euthanasia. A pus-filled tract within the rostrum was observed. Histopathology revealed granulomatous inflammation with hyphae morphologically consistent with Alternaria sp. isolated by culture.

  18. Automated and unbiased image analyses as tools in phenotypic classification of small-spored Alternaria species

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Hansen, Michael Edberg; Smedsgaard, Jørn

    2005-01-01

    For more than 25 years, controversy has surrounded the characterization and differentiation of small-spored Alternaria spp. And, therefore, the application of names of several species that are involved in the pathology of diseases related to host-specific toxin production. The name A. alternata o...

  19. A polyphasic approach for the characterization of endophytic Alternaria strains isolated from grapevines

    DEFF Research Database (Denmark)

    Polizzotto, Rachele; Andersen, Birgitte; Martini, Marta

    2012-01-01

    A polyphasic approach was set up and applied to characterize 20 fungal endophytes belonging to the genus Alternaria, recovered from grapevine in different Italian regions.Morphological, microscopical, molecular and chemical investigations were performed and the obtained results were combined in a...

  20. Biological control of Alternaria radicina in seed production of carrots with Ulocladium atrum

    NARCIS (Netherlands)

    Köhl, J.; Langerak, C.J.; Meekes, E.T.M.; Molhoek, W.M.L.

    2004-01-01

    Black rot of carrots is caused by seed-borne Alternaria radicina. Biological control of seed infestation by treatments applied to plants in flower during seed production with the fungal antagonist Ulocladium atrum was investigated in laboratory and field experiments resulting in a reduction of seed

  1. Assessment of early blight (Alternaria solani) resistance in tomato using a droplet inoculation method

    NARCIS (Netherlands)

    Chaerani, R.; Groenwold, R.; Stam, P.; Voorrips, R.E.

    2006-01-01

    A droplet inoculation method was used for evaluation of tomato resistance to early blight, a destructive foliar disease of tomato caused by Alternaria solani (Ellis and Martin) Sorauer. In this test method, leaflets are inoculated with small droplets of a spore suspension in either water or a 0.1% a

  2. QTL identification for early blight resistance (Alternaria solani) in a Solanum lycopersicum x S. arcanum cross.

    NARCIS (Netherlands)

    Chaerani, R.; Smulders, M.J.M.; Linden, van der C.G.; Vosman, B.; Stam, P.; Voorrips, R.E.

    2007-01-01

    Alternaria solani (Ellis and Martin) Sorauer, the causal agent of early blight (EB) disease, infects aerial parts of tomato at both seedling and adult plant stages. Resistant cultivars would facilitate a sustainable EB management. EB resistance is a quantitatively expressed character, a fact that ha

  3. Characterization of Alternaria isolates and reaction of potato genotypes to early blight

    Directory of Open Access Journals (Sweden)

    Thayssa Vilela Miguel Alvarenga

    Full Text Available ABSTRACT: Early blight is one of the most important fungal diseases of potato. The objective of this study was to evaluate the in vitro reaction of potato genotypes to the severity of early blight and compare the species Alternaria solani and Alternaria grandis , etiologic agents of disease, through the evaluation of physiological characteristics. Twenty-two genotypes of the Potato Breeding Program at UFLA, two cultivars, Aracy and Bintje, patterns of resistance and susceptibility, respectively were evaluated. For inoculation, three isolates of A. grandis and two isolates of A. solani were used. Plantlets obtained in vitro were inoculated with a 5mm diameter mycelial disk of isolates Alternaria spp. of. These were incubated in severity and classified according to the rating scale. Isolates of Alternaria spp. were evaluated for mycelial growth index (MGI and for formation of mycelial compatibility groups (MCG. The methodology for evaluating the in vitro reaction of genotypes to severity of early blight was efficient for both isolates. The isolates of A. solani and A. grandis were similar in their aggressiveness. The isolates of A. grandis MGI's had higher, and therefore mycelium grew faster when compared to those isolated from A. solani . The occurrence of mycelial compatibility among isolates of A. solani and A. grandis indicated the possible occurrence of parasexual cycle.

  4. Eficiência e custo do controle químico da mancha de alternaria em tangor murcote Efficiency and cost of chemical control of alternaria brown spot

    Directory of Open Access Journals (Sweden)

    Adimara Bentivoglio Colturato

    2009-09-01

    Full Text Available A mancha de alternaria, causada por Alternaria alternata f. sp. citri, afeta tangelos Minneola, tangerinas Dancy, tangores Murcote e, menos freqüentemente, tangelos Orlando, tangerinas Novas, Lees e Sunburst. Esta doença causa desfolha grave, queda de frutos e manchas nas frutas. O objetivo deste trabalho foi estabelecer o melhor fungicida e a melhor dose para o controle da mancha marrom de alternaria. O delineamento experimental foi de parcelas subdivididas em blocos, com 10 tratamentos principais e 3 doses (subparcelas, com 5 repetições. Foram feitas 5 aplicações, com intervalo de 15 dias. Os tratamentos foram: azoxystrobin, pyraclostrobin, trifloxystrobin, trifloxystrobin + tebuconazole (2 aplicações seguido de 3 aplicações de mancozeb, difenoconazole, trifloxystrobin + propiconazole, iprodione, trifloxystrobin + propineb (2 aplicações seguido de 3 aplicações de oxicloreto de cobre, oxicloreto de cobre + óleo e testemunha. Simultaneamente foram feitas avaliações de incidência e número de lesões por folha. Ao surgimento dos frutos foram avaliadas a incidência em frutos e a produtividade em Kg/ha. Todos os tratamentos foram superiores à testemunha quanto a produtividade. Entre os produtos utilizados o tratamento com trifloxystrobin + propiconazole foi rentável comparando-se custo e produtividade.Alternaria brown spot, caused by Alternaria alternata sp. citri, attacks with more intensity the Tangelos Minneola, tangerine Dancy, and Murcotts, and with less intensity the tangelos Orlando and the tangerinas Novas, Lees and Sunburst. This disease causes severe defoliation and drop or necrotic spots in the fruits. The aim of this work was to evaluated the chemical control of brown spot, and to define the most appropriate dosage of fungicide to control it. The experimental design was split-spot, with ten treatments and 3 doses of fungicides, with five replicates, the fungicides were: azoxystrobin, pyraclostrobin, trifloxystrobin

  5. Identification and characterization of cDNA sequences encoding the HIS3 and LEU2 genes of the fungus Alternaria tenuissima

    Institute of Scientific and Technical Information of China (English)

    Ying Wan; Xuli Wang; Yun Huang; Dewen Qiu; Linghuo Jiang

    2008-01-01

    Alternaria tenuissima is a fungus widely present in the environment and could cause diseases in plants and humans.In this study,through a yeast genetic approach,cDNA sequences were isolated and characterized for the AtHIS3 and AtLEU2 genes.AtHIS3 cDNA encodes a protein of 238 amino acids,while AtLEU2 cDNA encodes a protein of 363 amino acids.Based on the phylogenetic analysis of amino acid sequences of AtHis3p and AtLeu2p,A.tenuissima is closely related to the plant pathogenic fungus Phaeosphaeria nodorum.This study provides two genetic markers for studies of functions of genes regulating development,morphology,and virulence of A.tenuissima.

  6. Modification of primary and secondary metabolism of potato plants by nitrogen application differentially affects resistance to Phytophthora infestans and Alternaria solani.

    Science.gov (United States)

    Mittelstrass, K; Treutter, D; Plessl, M; Heller, W; Elstner, E F; Heiser, I

    2006-09-01

    Potato plants ( SOLANUM TUBEROSUM L. cv. Indira) were grown at two levels of N supply in the greenhouse. Plants supplied with 0.8 g N per plant (high N variant) showed significantly increased biomass as compared to plants without additional N fertilisation (low N variant). C/N ratio was lower and protein content was higher in leaves of the high N variant. The concentration of chlorogenic acids and flavonols was significantly lower in leaves from the high N variant. Whereas resistance to ALTERNARIA SOLANI increased when plants were supplied with additional nitrogen, these plants were more susceptible to PHYTOPHTHORA INFESTANS. After infection with both pathogens, we found a strong induction of p-coumaroylnoradrenaline and p-coumaroyloctopamine, which are identified for the first time in potato leaves and are discussed as resistance factors of other solanaceous plants.

  7. Plant resistance within the Rutaceae to Asian citrus psyllid

    Science.gov (United States)

    USDA-ARS recently initiated research on host plant resistance to the Asian citrus psyllid. The psyllid is an important invasive pest of citrus in the United States because it transmits a serious disease of citrus known as huanglongbing (citrus greening). There is no cure for this bacterial disease. ...

  8. 7 CFR 319.56-38 - Citrus from Chile.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Citrus from Chile. 319.56-38 Section 319.56-38... from Chile. Clementines (Citrus reticulata Blanco var. Clementine), mandarins (Citrus reticulata Blanco), and tangerines (Citrus reticulata Blanco) may be imported into the United States from Chile,...

  9. A comparison of plant species for rearing Asian citrus psyllid

    Science.gov (United States)

    Five plant genotypes were compared with respect to Asian citrus psyllid (ACP) reproduction potential: Bergera koenigii, Citrus aurantiifolia, C. macrophylla, C. taiwanica and Murraya paniculata. Asian citrus psyllid reproduction is dependent on young flush and thus Asian citrus psyllid production po...

  10. Transcriptional Responses of the Bdtf1-Deletion Mutant to the Phytoalexin Brassinin in the Necrotrophic Fungus Alternaria brassicicola

    Directory of Open Access Journals (Sweden)

    Yangrae Cho

    2014-07-01

    Full Text Available Brassica species produce the antifungal indolyl compounds brassinin and its derivatives, during microbial infection. The fungal pathogen Alternaria brassicicola detoxifies brassinin and possibly its derivatives. This ability is an important property for the successful infection of brassicaceous plants. Previously, we identified a transcription factor, Bdtf1, essential for the detoxification of brassinin and full virulence. To discover genes that encode putative brassinin-digesting enzymes, we compared gene expression profiles between a mutant strain of the transcription factor and wild-type A. brassicicola under two different experimental conditions. A total of 170 and 388 genes were expressed at higher levels in the mutants than the wild type during the infection of host plants and saprophytic growth in the presence of brassinin, respectively. In contrast, 93 and 560 genes were expressed, respectively, at lower levels in the mutant than the wild type under the two conditions. Fifteen of these genes were expressed at lower levels in the mutant than in the wild type under both conditions. These genes were assumed to be important for the detoxification of brassinin and included Bdtf1 and 10 putative enzymes. This list of genes provides a resource for the discovery of enzyme-coding genes important in the chemical modification of brassinin.

  11. Selection and differentiation of Bacillus spp. Antagonistic to Fusarium oxysporum f.sp. lycopersici and Alternaria solani infecting Tomato.

    Science.gov (United States)

    Shanmugam, Veerubommu; Atri, Kamini; Gupta, Samriti; Kanoujia, Nandina; Naruka, Digvijay Singh

    2011-03-01

    Antagonistic Bacillus spp. displaying in vitro production of siderophore, chitinase, and β-1,3-glucanase were identified from dual culture assays. In independent greenhouse studies, seed bacterization and soil application of Bacillus atrophaeus S2BC-2 challenge inoculated with Fusarium oxysporum f.sp. lycopersici (FOL) and Alternaria solani (AS) recorded low percent disease index of 25.3 and 28.7, respectively, over nonbacterised pathogen control (44.3 and 56.4). The low disease incidence corroborated with tomato growth promotion with high vigor index (8,041.2) and fresh plant weight (82.5 g) on challenge inoculation with FOL. Analysis of root and leaf samples in rhizobacterial treatment challenged with FOL and AS revealed maximum induction of chitinase (1.9 and 1.7 U/mg of protein, respectively) and β-1,3-glucanase (23.5 and 19.2 U/mg of protein, respectively). In native gel activity assays, the rhizobacterial treatment on challenge inoculation strongly expressed three high intensity PO isoforms along with one low intensity isoform. In studies on genetic diversity of the Bacillus strains by repetitive extragenomic palindromic-polymerase chain reaction (REP-PCR) and amplified rDNA restriction analysis (ARDRA) patterns, ARDRA was more highly discriminant than REP-PCR and allowed grouping of the strains and differentiation of the antagonistic strains from other isolates.

  12. Transcriptomic profiling of citrus fruit peel tissues reveals fundamental effects of phenylpropanoids and ethylene on induced resistance

    NARCIS (Netherlands)

    Ballester Frutos, A.R.; Lafuente, M.T.; Forment, J.; Gadea, J.; Vos, de C.H.R.; Bovy, A.G.; Gonzalez-Candelas, L.

    2011-01-01

    Penicillium spp. are the major postharvest pathogens of citrus fruit in Mediterranean climatic regions. The induction of natural resistance constitutes one of the most promising alternatives to avoid the environmental contamination and health problems caused by chemical fungicides. To understand the

  13. Identification of gene candidates associated with huanglongbing tolerance using Candidatus Liberibacter asiaticus flagellin 22 as a proxy to challenge citrus

    Science.gov (United States)

    Plant defense elicited by pathogen-associated molecular patterns (PAMPs) is an important component of disease resistance. Previous research indicated the canker resistance in citrus correlates with responsiveness to Xcc-flg22, the 22 amino acid PAMP from the flagellin of Xanthomonas citri ssp. citri...

  14. Efficacy of a pyrimidine derivative to control spot disease on Solanum melongena caused by Alternaria alternata

    Directory of Open Access Journals (Sweden)

    Nemat M. Hassan

    2013-07-01

    Full Text Available The pyrimidine derivative (4,6-dimethyl-N-phenyldiethyl pyrimidine, DPDP was tested as a foliar spray fungicide at 50 mg l−1 for protection of eggplant (Solanum melongena from spot disease caused by Alternaria alternata. Varied concentrations of DPDP (10–50 mg l−1 differentially inhibited mycelial growth, conidial count and conidial germination of A. alternata growth in vitro; the magnitude of inhibition increased with increasing concentration. In vivo, an experiment was conducted in pots using a complete block randomized design and repeated twice with three replications and four treatments (control, A. alternata alone, DPDP alone and combination of DPDP and A. alternata for 5 weeks (1 plant in pot × 3 pots per set (3 replications per treatment × 4 sets (4 treatments × 5 weeks × 2 experimental repetitions = 120 pots. In this experiment, 10-day-old eggplant seedlings were transplanted in pots and then inoculated with A. alternata, DPDP or their combination 1 week later. Leaves of the A. alternata-infected eggplant suffered from chlorosis, necrosis and brown spots during the subsequent 5 weeks. Disease intensity was obvious in infected leaves but withdrawn by DPDP. There were relationships between incidence and severity, greater in plant leaves infected A. alternata alone and diminished with the presence of DPDP. Moreover, the infection resulted in reductions in growth, decreases in contents of anthocyanins, chlorophylls, carotenoids and thiols as well as inhibitions in activities of superoxide dismutase (SOD, glutathione peroxidase (GPX and glutathione-S-transferase (GST. Nonetheless, the application of DPDP at 50 mg led to a recovery of the infected eggplant; the infection-induced deleterious effects were mostly reversed by DPDP. However, treatment with DPDP alone seemed with no significant impacts. Due to its safe use to host and the inhibition for the pathogen, DPDP could be suggested as an efficient fungicide for

  15. Identification of A. arborescens, A. grandis, and A. protenta as new members of the European Alternaria population on potato.

    Science.gov (United States)

    Landschoot, Sofie; Vandecasteele, Michiel; De Baets, Bernard; Höfte, Monica; Audenaert, Kris; Haesaert, Geert

    2017-02-01

    Alternaria species, primarily the small-spored Alternaria alternata and the large-spored Alternaria solani, are considered a serious threat to potato cultivation. To develop control strategies, it is important to gain insight into the Alternaria population. Based on the sequence analyses of the internal transcribed spacer region (ITS) and the glyceraldehyde-3-phosphate dehydrogenase gene, the small-spored and large-spored Alternaria isolates could be separated from each other. Sequence analyses of the calmodulin gene and the RNA polymerase second largest subunit showed that besides A. solani also A. grandis and A. protenta were present in the large-spored Alternaria population. Sequence analyses of the Alternaria major allergen gene Alt a 1 and the elongation factor-α revealed that both A. alternata and species belonging to the Alternaria arborescens species complex were present in the small-spored Alternaria population. Furthermore, according to the histone h3 sequence the members of the A. arborescens species complex could be subdivided into two groups. Concerning the fitness, it was concluded that the mycelium growth rate of the large-spored isolates was significantly lower compared to the growth rate of the small-spored isolates. In contrast, the spore-germinating capacity and early growth of the large-spored isolates was greater compared to those of the small-spored isolates. Within the groups of small-spored and large-spored isolates there were no significant differences in fitness between the species. Copyright © 2016 British Mycological Society. All rights reserved.

  16. Cryopreservation and Cryotherapy of Citrus Cultivars

    Science.gov (United States)

    Long-term conservation of Citrus clones can be accomplished by cryopreservation. Shoot tips will survive liquid nitrogen exposure and storage when appropriately desiccated and treated with cryoprotectant solutions. In our research, vegetative Citrus budwood is shipped from Riverside to Fort Collin...

  17. Citrus water use in South Africa

    CSIR Research Space (South Africa)

    Vahrmeijer, JT

    2012-09-01

    Full Text Available intervenes through policy instruments to influence water use behaviour. Citrus growers need to take heed of these changes in policy as the majority of citrus orchards are irrigated and more detailed information on seasonal water requirements and irrigation...

  18. Understanding the dynamics of citrus water use

    CSIR Research Space (South Africa)

    Taylor, NJ

    2012-12-01

    Full Text Available The quantification of water use of citrus orchards is important in order to prevent stress developing in the orchard and to avoid wasting precious water resources. Measurement of citrus orchard water use is not possible under all environ...

  19. Rapid cyling plant breeding in citrus

    Science.gov (United States)

    Resistance or tolerance to huanglongbing (HLB) and other important traits have been identified in several citrus types and relatives and associated markers should be identified soon. What is urgently needed in addition is an accelerated strategy for citrus variety breeding. Identification and use of...

  20. Occurrence of root parsley pathogens inhabiting seeds

    Directory of Open Access Journals (Sweden)

    Bogdan Nowicki

    2013-12-01

    Full Text Available The studies on root parsley pathogens inhabiting seeds were conducted during 1981-1988 and in 1993. Filter paper method with prefreezing and keeping under light was used. Each test sample comprised 500 seeds. Pathogenicity of collected fungal isolates was tested following two laboratory methods. 238 seed samples were studied. 18 fungal species were found but only 7 proved to be important pathogens of root parsley. The most common inhabitants of root parsley seeds were Alternaria spp. A.allernata occurred on 74,8% of seeds but only a few isolates showed to be slightly pathogenic while A.petroselini and A.radicina were higly pathogenic and inhabited 11,4 and 4,2% of seeds, respectively. The second group of important pathogens were species of Fusarium found on 3,9% of seeds. F.avenaceum dominated as it comprised 48% of Fusarium isolates, the next were as follow: F.culmorum - 20%, F.equiseti - 15%, F.solani - 8%, F.oxysporum - 7% and F.dimerum -2%. Some fungi like Botrytis cinerea, Septoria petroselini and Phoma spp. inhabited low number of seeds, respectively O,4; 0,5 and 0,8%, but they were highly pathogenic to root parsley. The fungi: Bipolaris sorokiniana, Drechslera biseptata, Stemphylium botryosum and Ulocludium consortiale showed slight pathogenicity. They were isolated from 3,8% of seeds.

  1. The WRKY Transcription Factor Family in Citrus: Valuable and Useful Candidate Genes for Citrus Breeding.

    Science.gov (United States)

    Ayadi, M; Hanana, M; Kharrat, N; Merchaoui, H; Marzoug, R Ben; Lauvergeat, V; Rebaï, A; Mzid, R

    2016-10-01

    WRKY transcription factors belong to a large family of plant transcriptional regulators whose members have been reported to be involved in a wide range of biological roles including plant development, adaptation to environmental constraints and response to several diseases. However, little or poor information is available about WRKY's in Citrus. The recent release of completely assembled genomes sequences of Citrus sinensis and Citrus clementina and the availability of ESTs sequences from other citrus species allowed us to perform a genome survey for Citrus WRKY proteins. In the present study, we identified 100 WRKY members from C. sinensis (51), C. clementina (48) and Citrus unshiu (1), and analyzed their chromosomal distribution, gene structure, gene duplication, syntenic relation and phylogenetic analysis. A phylogenetic tree of 100 Citrus WRKY sequences with their orthologs from Arabidopsis has distinguished seven groups. The CsWRKY genes were distributed across all ten sweet orange chromosomes. A comprehensive approach and an integrative analysis of Citrus WRKY gene expression revealed variable profiles of expression within tissues and stress conditions indicating functional diversification. Thus, candidate Citrus WRKY genes have been proposed as potentially involved in fruit acidification, essential oil biosynthesis and abiotic/biotic stress tolerance. Our results provided essential prerequisites for further WRKY genes cloning and functional analysis with an aim of citrus crop improvement.

  2. Deciphering the Bacterial Microbiome in Huanglongbing-Affected Citrus Treated with Thermotherapy and Sulfonamide Antibiotics.

    Directory of Open Access Journals (Sweden)

    Chuanyu Yang

    Full Text Available Huanglongbing (HLB is a serious citrus disease that threatens the citrus industry. In previous studies, sulfonamide antibiotics and heat treatment suppressed 'Candidatus Liberibacter asiaticus' (Las, but did not completely eliminate the Las. Furthermore, there are few reports studying the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. In this study, combinations of heat (45°C or 40°C and sulfonamide treatment (sulfathiazole sodium-STZ, or sulfadimethoxine sodium-SDX were applied to HLB-affected citrus. The bacterial microbiome of HLB-affected citrus following thermotherapy and/or chemotherapy was characterized by PhyloChipTMG3-based metagenomics. Our results showed that the combination of thermotherapy at 45°C and chemotherapy with STZ and SDX was more effective against HLB than thermotherapy alone, chemotherapy alone, or a combination of thermotherapy at 40°C and chemotherapy. The PhyloChipTMG3-based results indicated that 311 empirical Operational Taxonomic Units (eOTUs were detected in 26 phyla. Cyanobacteria (18.01% were dominant after thermo-chemotherapy. Thermotherapy at 45°C decreased eOTUs (64.43% in leaf samples, compared with thermotherapy at 40°C (73.96% or without thermotherapy (90.68% and it also reduced bacterial family biodiversity. The eOTU in phylum Proteobacteria was reduced significantly and eOTU_28, representing "Candidatus Liberibacter," was not detected following thermotherapy at 45°C. Following antibiotic treatment with SDX and STZ, there was enhanced abundance of specific eOTUs belonging to the families Streptomycetaceae, Desulfobacteraceae, Chitinophagaceae, and Xanthomonadaceae, which may be implicated in increased resistance to plant pathogens. Our study further develops an integrated strategy for combating HLB, and also provides new insight into the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics.

  3. Deciphering the Bacterial Microbiome in Huanglongbing-Affected Citrus Treated with Thermotherapy and Sulfonamide Antibiotics.

    Science.gov (United States)

    Yang, Chuanyu; Powell, Charles A; Duan, Yongping; Shatters, Robert; Fang, Jingping; Zhang, Muqing

    2016-01-01

    Huanglongbing (HLB) is a serious citrus disease that threatens the citrus industry. In previous studies, sulfonamide antibiotics and heat treatment suppressed 'Candidatus Liberibacter asiaticus' (Las), but did not completely eliminate the Las. Furthermore, there are few reports studying the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. In this study, combinations of heat (45°C or 40°C) and sulfonamide treatment (sulfathiazole sodium-STZ, or sulfadimethoxine sodium-SDX) were applied to HLB-affected citrus. The bacterial microbiome of HLB-affected citrus following thermotherapy and/or chemotherapy was characterized by PhyloChipTMG3-based metagenomics. Our results showed that the combination of thermotherapy at 45°C and chemotherapy with STZ and SDX was more effective against HLB than thermotherapy alone, chemotherapy alone, or a combination of thermotherapy at 40°C and chemotherapy. The PhyloChipTMG3-based results indicated that 311 empirical Operational Taxonomic Units (eOTUs) were detected in 26 phyla. Cyanobacteria (18.01%) were dominant after thermo-chemotherapy. Thermotherapy at 45°C decreased eOTUs (64.43%) in leaf samples, compared with thermotherapy at 40°C (73.96%) or without thermotherapy (90.68%) and it also reduced bacterial family biodiversity. The eOTU in phylum Proteobacteria was reduced significantly and eOTU_28, representing "Candidatus Liberibacter," was not detected following thermotherapy at 45°C. Following antibiotic treatment with SDX and STZ, there was enhanced abundance of specific eOTUs belonging to the families Streptomycetaceae, Desulfobacteraceae, Chitinophagaceae, and Xanthomonadaceae, which may be implicated in increased resistance to plant pathogens. Our study further develops an integrated strategy for combating HLB, and also provides new insight into the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics.

  4. Association of IL-4RA single nucleotide polymorphisms, HLA-DR and HLA-DQ in children with Alternaria-sensitive moderate-severe asthma.

    Science.gov (United States)

    Knutsen, Alan P; Vijay, Hari M; Kariuki, Barbara; Santiago, Luis A; Graff, Ralph; Wofford, Jonathan D; Shah, Maulik R

    2010-03-18

    Asthma afflicts 6% to 8% of the United States population, and severe asthma represents approximately 10% of asthmatic patients. Several epidemiologic studies in the United States and Europe have linked Alternaria sensitivity to both persistence and severity of asthma. In order to begin to understand genetic risk factors underlying Alternaria sensitivity and asthma, in these studies we examined T cell responses to Alternaria antigens, HLA Class II restriction and HLA-DQ protection in children with severe asthma. Sixty children with Alternaria-sensitive moderate-severe asthma were compared to 49 children with Alternaria-sensitive mild asthma. We examined HLA-DR and HLA-DQ frequencies in Alternaria-sensitive asthmatic by HLA typing. To determine ratios of Th1/Th2 Alternaria-specific T-cells, cultures were stimulated in media alone, Alternaria alternata extract and Alt a1. Sensitivity to IL-4 stimulation was measured by up-regulation of CD23 on B cells. Children with Alternaria-sensitive moderate-severe asthma trended to have increased sensitivities to Cladosporium (46% versus 35%), to Aspergillus (43% versus 28%), and significantly increased sensitivities to trees (78% versus 57%) and to weeds (68% versus 48%). The IL-4RA ile75val polymorphism was significantly increased in Alternaria-sensitive moderate-severe asthmatics, 83% (0.627 allele frequency) compared to Alternaria-sensitive mild asthmatics, 57% (0.388 allele frequency). This was associated with increased sensitivity to IL-4 stimulation measured by significantly increased IL-4 stimulated CD23 expression on CD19+ and CD86+CD19+ B cells of Alternaria-sensitive moderate-severe asthmatics. IL-5 and IL-13 synthesis was significantly increased in Alternaria-sensitive moderate-severe asthmatics compared to mild asthmatics to Alternaria extract and Alt a1 stimulation. The frequency of HLA-DQB1*03 allele was significantly decreased in Alternaria-sensitive moderate-severe asthmatics compared to mild asthmatics, 39

  5. Association of IL-4RA single nucleotide polymorphisms, HLA-DR and HLA-DQ in children with Alternaria-sensitive moderate-severe asthma

    Directory of Open Access Journals (Sweden)

    Santiago Luis A

    2010-03-01

    Full Text Available Abstract Background Asthma afflicts 6% to 8% of the United States population, and severe asthma represents approximately 10% of asthmatic patients. Several epidemiologic studies in the United States and Europe have linked Alternaria sensitivity to both persistence and severity of asthma. In order to begin to understand genetic risk factors underlying Alternaria sensitivity and asthma, in these studies we examined T cell responses to Alternaria antigens, HLA Class II restriction and HLA-DQ protection in children with severe asthma. Methods Sixty children with Alternaria-sensitive moderate-severe asthma were compared to 49 children with Alternaria-sensitive mild asthma. We examined HLA-DR and HLA-DQ frequencies in Alternaria-sensitive asthmatic by HLA typing. To determine ratios of Th1/Th2 Alternaria-specific T-cells, cultures were stimulated in media alone, Alternaria alternata extract and Alt a1. Sensitivity to IL-4 stimulation was measured by up-regulation of CD23 on B cells. Results Children with Alternaria-sensitive moderate-severe asthma trended to have increased sensitivities to Cladosporium (46% versus 35%, to Aspergillus (43% versus 28%, and significantly increased sensitivities to trees (78% versus 57% and to weeds (68% versus 48%. The IL-4RA ile75val polymorphism was significantly increased in Alternaria-sensitive moderate-severe asthmatics, 83% (0.627 allele frequency compared to Alternaria-sensitive mild asthmatics, 57% (0.388 allele frequency. This was associated with increased sensitivity to IL-4 stimulation measured by significantly increased IL-4 stimulated CD23 expression on CD19+ and CD86+CD19+ B cells of Alternaria-sensitive moderate-severe asthmatics. IL-5 and IL-13 synthesis was significantly increased in Alternaria-sensitive moderate-severe asthmatics compared to mild asthmatics to Alternaria extract and Alt a1 stimulation. The frequency of HLA-DQB1*03 allele was significantly decreased in Alternaria-sensitive moderate

  6. Detection and molecular identification protocols for Phyllosticta citricarpa from citrus matter

    Directory of Open Access Journals (Sweden)

    Mariette Truter

    2012-03-01

    Full Text Available Strict quarantine measures for the export of South African citrus fruit to European and US markets require the development of sensitive and accurate detection methods for the pathogen Phyllosticta citricarpa – a fungus causing citrus black spot disease. Because of the presence of other, non-pathogenic Phyllosticta species, rapid and accurate verification of the Phyllosticta species present on exported citrus fruit is important to producers, exporters and regulatory authorities to prevent unnecessary losses. We have analysed over 800 samples collected over 7 years and have compared sample preparation and detection protocols applied in different environments: nurseries, production systems including phytosanitary inspections in orchards, pack houses and export terminals in order to compile protocols for the detection of P. citricarpa. Standard procedures of sample preparation and DNA extraction were adapted to suit diverse inoculum sources. Low pathogen numbers in symptomless green leaves, for example, obliged the use of a wet-dry enrichment technique constituting the stimulation of fungal growth for easier detection. Physical maceration was adapted for sturdy material using liquid nitrogen or bead beating. The use of a two-step polymerase chain reaction (PCR with nested primers significantly increased both the sensitivity and the specificity of the PCR performed on soil samples, overcoming problems with relatively impure DNA extracts and low pathogen numbers. The assays have proven to be highly consistent, thereby providing a reliable, reproducible and highly sensitive detection and diagnostic service to the southern African citrus industries in order to sustain market access.

  7. Evaluation of the Efficacy of Different Fungicide for the Management of Alternaria Leaf Spot Disease of Chilli

    Directory of Open Access Journals (Sweden)

    Manoj Kumar Yadav

    2015-03-01

    Full Text Available Alternaria leaf spot of chilli caused by Alternaria alternate is an important disease affecting chilly production areas in India. The disease is primarily controlled through the use of fungicidal seed treatments. In this study, different fungicides viz. Captol, Captan, Ziram, Captofol, Thiram, Indofill Z 78 and Indofill Z 45 were assessed for their ability to reduce the growth of Alternaria alternata under laboratory conditions. Maximum inhibition (100% was achieved by Captol and capton followed by captofol (89.5 % while 0.1 % dose given. This paper reports the efficacy of fungicides that can be used under field conditions to control alternaria leaf spot in tropical regions and demonstrates the use of a method of application that could significantly improve the efficacy of disease control.

  8. Citrus breeding, genetics and genomics in Japan

    Science.gov (United States)

    Omura, Mitsuo; Shimada, Takehiko

    2016-01-01

    Citrus is one of the most cultivated fruits in the world, and satsuma mandarin (Citrus unshiu Marc.) is a major cultivated citrus in Japan. Many excellent cultivars derived from satsuma mandarin have been released through the improvement of mandarins using a conventional breeding method. The citrus breeding program is a lengthy process owing to the long juvenility, and it is predicted that marker-assisted selection (MAS) will overcome the obstacle and improve the efficiency of conventional breeding methods. To promote citrus molecular breeding in Japan, a genetic mapping was initiated in 1987, and the experimental tools and resources necessary for citrus functional genomics have been developed in relation to the physiological analysis of satsuma mandarin. In this paper, we review the progress of citrus breeding and genome researches in Japan and report the studies on genetic mapping, expression sequence tag cataloguing, and molecular characterization of breeding characteristics, mainly in terms of the metabolism of bio-functional substances as well as factors relating to, for example, fruit quality, disease resistance, polyembryony, and flowering. PMID:27069387

  9. Citrus breeding, genetics and genomics in Japan.

    Science.gov (United States)

    Omura, Mitsuo; Shimada, Takehiko

    2016-01-01

    Citrus is one of the most cultivated fruits in the world, and satsuma mandarin (Citrus unshiu Marc.) is a major cultivated citrus in Japan. Many excellent cultivars derived from satsuma mandarin have been released through the improvement of mandarins using a conventional breeding method. The citrus breeding program is a lengthy process owing to the long juvenility, and it is predicted that marker-assisted selection (MAS) will overcome the obstacle and improve the efficiency of conventional breeding methods. To promote citrus molecular breeding in Japan, a genetic mapping was initiated in 1987, and the experimental tools and resources necessary for citrus functional genomics have been developed in relation to the physiological analysis of satsuma mandarin. In this paper, we review the progress of citrus breeding and genome researches in Japan and report the studies on genetic mapping, expression sequence tag cataloguing, and molecular characterization of breeding characteristics, mainly in terms of the metabolism of bio-functional substances as well as factors relating to, for example, fruit quality, disease resistance, polyembryony, and flowering.

  10. IN VITRO ANTAGONISM AND EVALUATION OF CHITINASE ACTIVITY OF BACTERIAâBACILLUS CIRCULANS AGAINST PATHOGENIC FUNGI IN VIGNA UNGUICULATA

    OpenAIRE

    Florentyna Rodrigues; Priadharsini.K; S. Suja; P. Palani

    2014-01-01

    Scientists of agriculture and plant pathology are on the lookout for potential biological control agents to control the plant pathogenic organisms in order to avoid soil contamination. Rhizospheric bacteria are excellent agents to control soil-borne plant pathogens. In this study an attempt has been made to evaluate the antagonistic activity of a bacterial strain Bacillus circulans against Curvularia lunata, Alternaria alternata and Cladosporium sp., which are important seed and soil borne pa...

  11. 78 FR 8435 - Importation of Fresh Citrus Fruit From Uruguay, Including Citrus Hybrids and Fortunella

    Science.gov (United States)

    2013-02-06

    ... States through the importation of citrus fruit. These include two fruit flies, Anastrepha fraterculus... conditions are designed to prevent the introduction of the following quarantine pests: Anastrepha fraterculus...

  12. Monitoring and assessment of airborne Cladosporium Link and Alternaria Nées spores in Sivrihisar (Eskisehir), Turkey.

    Science.gov (United States)

    Erkara, Ismuhan Potoglu; Ilhan, Semra; Oner, Setenay

    2009-01-01

    The spores of Cladosporium spp. and Alternaria spp., commonly described as the most allergenic spores, were collected by means of Durham gravimetric sampler from the Sivrihisar (Eskisehir) atmosphere throughout 2005 to 2006. The weekly variations in spores/cm(2) of Cladosporium and Alternaria were recorded. During this period, a total of 6,198 spores belonging to Cladosporium spp. and Alternaria spp. were recorded. Of these spores, 2,969 were identified in 2005 and 3,229 in 2006. While 69.55% of the total spores were those of Cladosporium spp., 30.45% were Alternaria spp. Relationships between airborne fungal spore presence and weather conditions were examined statistically. A Shapiro-Wilk test revealed that the airborne spores of Cladosporium spp. and Alternaria spp. had a normal distribution. Following this, Chi-square test, t test and Pearson correlation analysis were performed. The effects of temperature and relative humidity on the spore numbers of Cladosporium spp. and Alternaria spp. were significant according to the month in which they were collected (p < 0.01). The spore concentrations of each species reached to their highest levels in June 2006.

  13. Importancia del género Alternaria como productor de micotoxinas y agente causal de enfermedades humanas The importance of genus Alternaria in mycotoxins production and human diseases

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    M. Á. Pavón Moreno

    2012-12-01

    Full Text Available Alternaría es un género fúngico muy común, donde se incluyen numerosas especies saprofitas, endofíticas y patógenas ampliamente distribuidas en el suelo y la materia orgánica en descomposición. Incluye especies patógenas que pueden invadir los cultivos vegetales antes y después de la recolección y es responsable de considerables pérdidas económicas, debido a que reduce el rendimiento de las cosechas y produce alteraciones en los vegetales durante su almacenamiento. Las especies del género Alternaría sintetizan más de 70 metabolitos secundarios tóxicos para las plantas (fitotoxinas, algunos de los cuales afectan también a personas y animales, por lo que se consideran micotoxinas. La exposición a las toxinas de Alternaría spp. se ha relacionado con la aparición de efectos adversos para la salud en personas y animales y, en muchos casos, se ha demostrado que tienen capacidad genotóxica, mutagénica, carcinogénica y citotóxica. Las micotoxinas de Alternaría spp. se han aislado de frutas (manzana, pera, melón, albaricoque, uvas, uvas pasas, fresa, aceituna, cítricos e higos desecados, hortalizas (tomate, pimiento y zanahoria y tubérculos (patata, así como de numerosos alimentos procesados elaborados con materias primas contaminadas (zumos, conservas, salsas, etc.. Además, determinadas especies de Alternaría están implicadas en infecciones y alergias humanas, hasta el punto de que Alternaría se considera uno de los principales géneros fúngicos causantes de alergias.Alternaría is a cosmopolitan fungal genus that includes saprophytic, endophytic and pathogenic species, widely distributed in soil and organic matter in decomposition. Plant pathogenic species affect cereals, vegetables and fruit crops in the field and during storage. Alternaría spp. contamination is responsible for some of the world's most devastating plant diseases, causing serious reduction of crop yields and considerable economic losses. Alternar

  14. Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

    Science.gov (United States)

    Alquézar, Berta; Rodríguez, Ana; de la Peña, Marcos; Peña, Leandro

    2017-01-01

    Citrus aroma and flavor, chief traits of fruit quality, are derived from their high content in essential oils of most plant tissues, including leaves, stems, flowers, and fruits. Accumulated in secretory cavities, most components of these oils are volatile terpenes. They contribute to defense against herbivores and pathogens, and perhaps also protect tissues against abiotic stress. In spite of their importance, our understanding of the physiological, biochemical, and genetic regulation of citrus terpene volatiles is still limited. The availability of the sweet orange (Citrus sinensis L. Osbeck) genome sequence allowed us to characterize for the first time the terpene synthase (TPS) family in a citrus type. CsTPS is one of the largest angiosperm TPS families characterized so far, formed by 95 loci from which just 55 encode for putative functional TPSs. All TPS angiosperm families, TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g were represented in the sweet orange genome, with 28, 18, 2, 2, and 5 putative full length genes each. Additionally, sweet orange β-farnesene synthase, (Z)-β-cubebene/α-copaene synthase, two β-caryophyllene synthases, and three multiproduct enzymes yielding β-cadinene/α-copaene, β-elemene, and β-cadinene/ledene/allo-aromandendrene as major products were identified, and functionally characterized via in vivo recombinant Escherichia coli assays. PMID:28883829

  15. Expression profile of oxidative and antioxidative stress enzymes based on ESTs approach of citrus

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    Luis Antonio Peroni

    2007-01-01

    Full Text Available Plants not only evolve but also reduce oxygen in photosynthesis. An inevitable consequence of this normal process is the production of reactive oxygen species (ROS. Plants are adequately protected by the presence of multiple antioxidative enzymes in the cytosol and also in the different cell organelles such as chloroplasts, mitochondria, and peroxisomes. Traditionally, ROS were considered to be only a toxic byproduct of aerobic metabolism. However, recently it has become apparent that plants actively produce these molecules which may control many different physiological processes such as abiotic and biotic stress response, pathogen defense and systemic signaling. The search results using the Citrus Genome Program in Brazil (CitEST for oxidative stress and the antioxidant enzyme system in Citrus Sinensis variety ‘Pera IAC’ indicated that the multiple ROS-scavenging enzymes were expressed throughout all citrus tissues. The analyses demonstrated the ubiquitous expression of metallothioneins, probably indicating a constitutive expression pattern. Oxalate oxidase has been identified as the most abundant expressed gene in developing fruits, which suggests a specific function in the ripening of citrus fruit. Moreover, infected leaves with Xylella fastidiosa and Leprosis citri showed a massive change in their ROS gene expression profile which may indicate that the suppression of ROS detoxifying mechanisms may be involved in the induction of the diseases.

  16. Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

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    Berta Alquézar

    2017-08-01

    Full Text Available Citrus aroma and flavor, chief traits of fruit quality, are derived from their high content in essential oils of most plant tissues, including leaves, stems, flowers, and fruits. Accumulated in secretory cavities, most components of these oils are volatile terpenes. They contribute to defense against herbivores and pathogens, and perhaps also protect tissues against abiotic stress. In spite of their importance, our understanding of the physiological, biochemical, and genetic regulation of citrus terpene volatiles is still limited. The availability of the sweet orange (Citrus sinensis L. Osbeck genome sequence allowed us to characterize for the first time the terpene synthase (TPS family in a citrus type. CsTPS is one of the largest angiosperm TPS families characterized so far, formed by 95 loci from which just 55 encode for putative functional TPSs. All TPS angiosperm families, TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g were represented in the sweet orange genome, with 28, 18, 2, 2, and 5 putative full length genes each. Additionally, sweet orange β-farnesene synthase, (Z-β-cubebene/α-copaene synthase, two β-caryophyllene synthases, and three multiproduct enzymes yielding β-cadinene/α-copaene, β-elemene, and β-cadinene/ledene/allo-aromandendrene as major products were identified, and functionally characterized via in vivo recombinant Escherichia coli assays.

  17. Characterization of Basidiomycetes associated with wood rot of citrus in southern Italy.

    Science.gov (United States)

    Roccotelli, Angela; Schena, Leonardo; Sanzani, Simona M; Cacciola, Santa O; Mosca, Saveria; Faedda, Roberto; Ippolito, Antonio; di San Lio, Gaetano Magnano

    2014-08-01

    The characterization of Basidiomycetes associated with wood rots in commercial citrus orchards in southern Italy revealed that both white and brown rot fungi are implicated in this disease. Fomitiporia mediterranea was the most prevalent species causing a white rot, followed by Fomitopsis sp. which, by contrast, was associated with brown rot wood decay. Furthermore, Phellinus spp. and other nonidentified basidiomycetous fungi showing genetic affinity with the genera Phellinus and Coniophora were occasionally isolated. Artificial inoculations on lemon (Citrus limon) branches showed a faster wood colonization by Fomitopsis sp. compared with F. mediterranea, indicating that the former species as a potentially serious pathogen of citrus trees. The analysis of F. mediterranea internal transcribed spacer (ITS) sequences revealed a high level of genetic variability, with 13 genotypes which were both homozygous (6 genotypes) and heterozygous (7 genotypes). The presence of heterozygous genomes based on ITS sequences has never been reported before for F. mediterranea. This, together with the high frequency of basidiomata on infected wood, unambiguously confirms the outcrossing nature of reproduction in F. mediterranea and the primary role of basidiospores in the dissemination of inoculum. Similarly, high genetic variability was observed analyzing Fomitopsis sp. Because basidiomata of this fungus have not been observed on citrus trees, it can be hypothesized that basidiospores are produced on alternative host plants.

  18. Annotation of the Asian Citrus Psyllid Genome Reveals a Reduced Innate Immune System.

    Science.gov (United States)

    Arp, Alex P; Hunter, Wayne B; Pelz-Stelinski, Kirsten S

    2016-01-01

    Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as Huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae). Hemipterans characterized to date lack a number of insect immune genes, including those associated with the Imd pathway targeting Gram-negative bacteria. The D. citri draft genome was used to characterize the immune defense genes present in D. citri. Predicted mRNAs identified by screening the published D. citri annotated draft genome were manually searched using a custom database of immune genes from previously annotated insect genomes. Toll and JAK/STAT pathways, general defense genes Dual oxidase, Nitric oxide synthase, prophenoloxidase, and cellular immune defense genes were present in D. citri. In contrast, D. citri lacked genes for the Imd pathway, most antimicrobial peptides, 1,3-β-glucan recognition proteins (GNBPs), and complete peptidoglycan recognition proteins. These data suggest that D. citri has a reduced immune capability similar to that observed in A. pisum, P. humanus, and R. prolixus. The absence of immune system genes from the D. citri genome may facilitate CLas infections, and is possibly compensated for by their relationship with their microbial endosymbionts.

  19. Degradation of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking.

    Science.gov (United States)

    Siegel, David; Feist, Michael; Proske, Matthias; Koch, Matthias; Nehls, Irene

    2010-09-01

    The stability of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking was investigated by model experiments using a spiked wholemeal wheat flour matrix. For alternariol and alternariol monomethyl ether, but not for altenuene, degradation products, formed through a sequence of hydrolysis and decarboxylation, could be identified in pilot studies. The simultaneous quantification of alternariol, alternariol monomethyl ether, altenuene, and the degradation products was achieved by a newly developed high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) multimethod. The obtained quantitative data indicate that the Alternaria mycotoxins are barely degraded during wet baking, while significant degradation occurs upon dry baking, with the stability decreasing in the order alternariol monomethyl ether>alternariol>altenuene. The novel degradation products could be detected after the wet baking of flour spiked with alternariol and in a sample survey of 24 commercial cereal based baking products.

  20. [Aerobiological study of Alternaria and Cladosporium conidia in the atmosphere of Almeria (SE Spain)].

    Science.gov (United States)

    Sabariego Ruiz, Silvia; Díaz de la Guardia Guerrero, Consuelo; Alba Sánchez, Francisca

    2004-09-01

    This study analysed the seasonal and intradiurnal behaviour of fungal spores from Alternaria and Cladosporium on air samples collected in the city of Almeria (SE Spain), as well as the influence that meteorological parameters have on the concentration of these type of spores. Aerobiological sampling was made during four years (1998-2001) using a Hirst-type volumetric spore trap. Spores of Alternaria and Cladosporium were detected throughout the year, reaching the highest concentrations from May to October. The diurnal patterns of these taxons reflected a presence similar of spores during a 24 h period, with values horary close to 4% of total sampling daily. The correlations show a positive association with temperature, hours of sunshine and accumulate rainfall, but negative with daily rainfall.

  1. Transcriptomics Analysis of Apple Leaves in Response to Alternaria alternata Apple Pathotype Infection

    Science.gov (United States)

    Zhu, Longming; Ni, Weichen; Liu, Shuai; Cai, Binhua; Xing, Han; Wang, Sanhong

    2017-01-01

    Alternaria blotch disease of apple (Malus × domestica Borkh.), caused by the apple pathotype of Alternaria alternata, is one of the most serious fungal diseases to affect apples. To develop an understanding of how apples respond to A. alternata apple pathotype (AAAP) infection, we examined the host transcript accumulation over the period between 0 and 72 h post AAAP inoculation. Large-scale gene expression analysis was conducted of the compatible interaction between “Starking Delicious” apple cultivar and AAAP using RNA-Seq and digital gene expression (DGE) profiling methods. Our results show that a total of 9080 differentially expressed genes (DEGs) were detected (>two-fold and FDR PRs) genes and phenylpropanoid/cyanoamino acid /flavonoid biosynthesis, were activated during this process. Our study also suggested that the cell wall defensive vulnerability and the down-regulation of most PRs and HSP70s in “Starking Delicious” following AAAP infection might interpret its susceptible to AAAP. PMID:28163714

  2. Altering Conidial Dispersal of Alternaria solani by Modifying Microclimate in Tomato Crop Canopy.

    Science.gov (United States)

    Jambhulkar, Prashant Prakash; Jambhulkar, Nitiprasad; Meghwal, Madanlal; Ameta, Gauri Shankar

    2016-12-01

    Early blight of tomato caused by Alternaria solani, is responsible for severe yield losses in tomato. The conidia survive on soil surface and old dry lower leaves of the plant and spread when suitable climatic conditions are available. Macroclimatic study reveals that highest inoculum concentration of Alternaria spores appeared in May 2012 to 2013 and lowest concentration during January 2012 to 2013. High night temperature positively correlated and significantly (P solani conidial density, tomato leaf damage and microclimatic parameters as compar to tomato alone (T). Tomato-marigold intercropping-plastic mulching treatment (T + M + P) showed 35-39% reduction in disease intensity as compared to tomato alone. When intercropped with tomato, marigold served as barrier to conidial movement and plastic mulching prevented evapotranspiration and reduced the canopy RH that resulted in less germination of A. solani spores. Marigold intercropping and plastic mulching served successfully as physical barrier against conidial dissemination to diminish significantly the tomato foliar damage produced by A. solani.

  3. Caracterização morfofisiológica e identificação molecular de isolados de Guignardia citricarpa, agente patogênico da mancha preta dos citros = Morphophysiological characterization and molecular identification of isolates of Guignardia citricarpa, a pathogenic agent of the citrus black spot

    Directory of Open Access Journals (Sweden)

    Marilda Pereira Caixeta

    2008-12-01

    Full Text Available O presente trabalho teve como objetivo identificar 11 isolados de Guignardia citricarpa, agente causal da mancha preta dos citros (MPC, obtidos de frutas cítricas sintomáticas de diferentes regiões geográficas, por meio da PCR e caracterização morfofisiológica das estruturas propagativas, esporulação e crescimento micelial emdiferentes meios de cultura, temperaturas e regimes de luz, nas condições de laboratório. Pelo teste de PCR, todos os isolados foram identificados como o patógeno G. citricarpa. Os isolados caracterizados foram submetidos às temperaturas de 20, 25 e 30ºC, em regime de luz contínua, escuro contínuo e fotoperíodos de 12 horas, durante 24 dias. Utilizaram-se os meios de cultura aveia-ágar (AA, batata-dextrose-ágar (BDA e cenoura-dextrose-ágar (CDA. Os resultados mostraram que ocorreu interação entre os diferentes meios de cultura, temperaturas e fotoperíodos. O meio de cultura que melhor estimulou o crescimento micelial foi o CDA a 25ºC sob o fotoperíodo de 12h. A maior produção de esporos (conídios foi verificada no meio BDA a 20ºC, no fotoperíodo de 12 horas. No meio CDA, não ocorreu esporulação de nenhum isolado. Sob a temperatura de 30ºC, foiverificada apenas a produção de hifas e picnídios para a maioria dos isolados, em todos os meios de cultura e fotoperíodo testados.Thepresent work aims to identify 11 isolates of Guignardia citricarpa, the causal agent of the citrus black spot (CBS, obtained from affected fruit in different geographical regions, through PCR and morphophysiological characterization of propagative structures, sporing and mycelial growth in different means of culture, temperatures and photoperiods, under laboratory conditions. Through the PCR test, all isolates were identified as being the G.citricarpa pathogen. The characterized isolates were subjected to evaluations at temperatures of 20, 25 and 30ºC, in continuous light, continuous darkness, and alternating 12

  4. Scopoletin is a phytoalexin against Alternaria alternata in wild tobacco dependent on jasmonate signalling

    OpenAIRE

    Sun, Huanhuan; WANG, Lei; ZHANG, BAOQIN; Ma, Junhong; Hettenhausen, Christian; Cao, Guoyan; Sun, Guiling; Wu, Jianqiang; Wu, Jinsong

    2014-01-01

    Alternaria alternata (tobacco pathotype) is a necrotrophic fungus causing severe losses in Nicotiana species by infection of mature leaves. Similar to what has been observed in cultivated tobacco, N. tabacum, young leaves of wild tobacco, N. attenuata, were more resistant to A. alternata than mature leaves, and this was correlated with stronger blue fluorescence induced after infection. However, the nature of the fluorescence-emitting compound, its role in defence, and its regulation were not...

  5. Role of micronutrients in defense to white rust and Alternaria blight infecting Indian mustard.

    Science.gov (United States)

    Rathi, A S; Singh, Dhiraj; Avtar, Ram; Kumar, Pawan

    2015-03-01

    Field experiments were carried out at Oilseeds Research Area of CCS Haryana Agricultural University, Hisar during rabi, 2008-09 to 2011-12 to find out the possible role of soil application of different micronutrients alone and in combinations in defense to white rust and Alternaria blight diseases in Indian mustard [Brassica juncea (L.) Czern & Coss.]. Among the sole application of micronutrients, minimum disease severity of both white rust (35.0%) and Alternaria blight (31.8%) was observed when S @ 40 kg ha in the form of Gypsum was applied as basal dose in the soil. When Gypsum was supplemented with Borax @10 kg ha(-1) or with ZnSO4 @15 kg ha(-1) the level of tolerance seems to be improved for both the diseases as compared to the sole treatment of each nutrient, i.e., ZnSO4 @ 15 kg/ha, Borax @ 10 kg ha' and Gypsum @ 250 kg ha(-1). Furthermore, minimum disease severity of both white rust (31.3 %) and Alternaria blight (26.3 %) was observed with soil application of ZnSO4 @ 15 kg ha(-1) + Borax @ 10 kg ha(-1) + Gypsum @250 kg ha(-1) as basal dose as compared to the severity of white rust (43.6%) and Alternaria blight (38.6%) in untreated check. Significant increase in seed yield (1612 kg ha(-1)) was also recorded in above mentioned treatment as compared to the yield (1337 kg ha(-1)) in untreated check. These findings will also be helpful in maintaining soil health and minimizing the losses due to both the fungal diseases for eco-friendly sustainability of Indian mustard.

  6. PHYTOCHEMICAL SCREENING AND IN-VITRO ANTIFUNGAL INVESTIGATION OF PARTHENIUM HYSTEROPHORUS EXTRACTS AGAINST ALTERNARIA ALTERNATA

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    Singh Padma

    2013-07-01

    Full Text Available The extensive use of fungicides are polluting the environment and giving rise to undesirable biological effects on animal and human beings. Therefore use of plant extracts as biological control agents is being popularized in recent years. Alternaria alternata is reported for causing foliage disease in several important vegetables and crops. In an approach towards the development of eco friendly antifungal compound for controlling plant diseases caused by Alternaria alternata different extracts of Parthenium hysterophorus were tested for their antifungal potential. Parthenium hysterophorus is considered as an obnoxious weed, growing on waste land. The four different solvent extracts viz., aqueous, methanol, acetone and ethanol extracts of leaves of Parthenium hysterophorus was evaluated from antifungal potential against four different isolates of Alternaria alternata isolated from potato (Solanum tuberosum, onion (Allium cepa, tomato (Lycopersicon esculentum and mustard (Brassica compestris by food poison technique. The ethanolic extract showed complete inhibition against the four isolates i.e. 100 % followed by acetone and methanol extracts which was approximately 96 % and 76 % respectively, while aqueous extract do not showed any antifungal activity. Thus the result showed that the ethanolic extract was the best extract to be used. The phytochemical analysis revealed the presence of alkaloid, glycoside, steroid, saponin in varying concentration in different extracts which might be the cause of antifungal potential. The present study supports the use of leaf extract of Parthenium hysterophorus as biofungicides for the disease caused by Alternaria alternata. This will help to save the environment from chemical hazards as most of the synthetic fungicide constitute mercury, zinc etc which are toxic for nature.

  7. Antimicrobial activity of wax and hexane extracts from Citrus spp. peels

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    Susana Johann

    2007-09-01

    Full Text Available Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp., two human pathogens (Trichophyton mentagrophytes and Microsporum canis, and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus. Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin from C. limon.

  8. Antimicrobial activity of wax and hexane extracts from Citrus spp. peels.

    Science.gov (United States)

    Johann, Susana; Oliveira, Vetúria Lopes de; Pizzolatti, Moacir G; Schripsema, Jan; Braz-Filho, Raimundo; Branco, Alexsandro; Smânia Jr, Artur

    2007-09-01

    Antibacterial and antifungal properties of wax and hexane extracts of Citrus spp. peels were tested using bioautographic and microdilution techniques against three plant pathogenic fungi (Penicillium digitatum, Curvularia sp., and Colletotrichum sp.), two human pathogens (Trichophyton mentagrophytes and Microsporum canis), and two opportunistic bacteria (Escherichia coli and Staphylococcus aureus). Two polymethoxylated flavonoids and a coumarin derivative, were isolated and identified from peel extracts, which presented antimicrobial activity especially against M. canis and T. mentagrophytes: 4',5,6,7,8-pentamethoxyflavone (tangeritin) and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin) from C. reticulata; and 6,7-dimethoxycoumarin (also known as escoparone, scoparone or scoparin) from C. limon.

  9. Production of the Allergenic Protein Alt a 1 by Alternaria Isolates from Working Environments

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    Justyna Skóra

    2015-02-01

    Full Text Available The aim of the study was to evaluate the ability of Alternaria isolates from workplaces to produce Alt a 1 allergenic protein, and to analyze whether technical materials (cellulose, compost, leather present within the working environment stimulate or inhibit Alt a 1 production (ELISA test. Studies included identification of the isolated molds by nucleotide sequences analyzing of the ITS1/ITS2 regions, actin, calmodulin and Alt a 1 genes. It has been shown that Alternaria molds are significant part of microbiocenosis in the archive, museum, library, composting plant and tannery (14%–16% frequency in the air. The presence of the gene encoding the Alt a 1 protein has been detected for the strains: Alternaria alternata, A. lini, A. limoniasperae A. nobilis and A. tenuissima. Environmental strains produced Alt a 1 at higher concentrations (1.103–6.528 ng/mL than a ATCC strain (0.551–0.975 ng/mL. It has been shown that the homogenization of the mycelium and the use of ultrafiltration allow a considerable increase of Alt a 1 concentration. Variations in the production of Alt a 1 protein, depend on the strain and extraction methods. These studies revealed no impact of the technical material from the workplaces on the production of Alt a 1 protein.

  10. Alternariol 9-methyl ether from the endophytic fungus Alternaria sp. Samif01 and its bioactivities

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    Jingfeng Lou

    2016-03-01

    Full Text Available Abstract One bioactive compound, identified as alternariol 9-methyl ether, was isolated from the crude extract of the endophytic fungus Alternaria sp. Samif01 residing in the roots of Salvia miltiorrhiza Bunge. Alternariol 9-methyl ether was active against bacteria with minimum inhibitory concentration values ranging from 25 to 75 µg/mL and median inhibitory concentration (IC50 values ranging from 16.00 to 38.27 µg/mL. The IC50 value of alternariol 9-methyl ether against spore germination of Magnaporthe oryzae was 87.18 µg/mL. Alternariol 9-methyl ether also showed antinematodal activity against Bursaphelenchus xylophilus and Caenorhabditis elegans with IC50 values of 98.17 µg/mL and 74.62 µg/mL, respectively. This work is the first report on alternariol 9-methyl ether and its biological activities from the endophytic fungus Alternaria sp. Samif01 derived from S. miltiorrhiza Bunge. The results indicate the potential of Alternaria sp. Samif01 as a source of alternariol 9-methyl ether and also support that alternariol 9-methyl ether is a natural compound with high potential bioactivity against microorganisms.

  11. Alternariol 9-methyl ether from the endophytic fungus Alternaria sp. Samif01 and its bioactivities.

    Science.gov (United States)

    Lou, Jingfeng; Yu, Ruiting; Wang, Xiaohan; Mao, Ziling; Fu, Linyun; Liu, Yang; Zhou, Ligang

    2016-01-01

    One bioactive compound, identified as alternariol 9-methyl ether, was isolated from the crude extract of the endophytic fungus Alternaria sp. Samif01 residing in the roots of Salvia miltiorrhiza Bunge. Alternariol 9-methyl ether was active against bacteria with minimum inhibitory concentration values ranging from 25 to 75μg/mL and median inhibitory concentration (IC50) values ranging from 16.00 to 38.27μg/mL. The IC50 value of alternariol 9-methyl ether against spore germination of Magnaporthe oryzae was 87.18μg/mL. Alternariol 9-methyl ether also showed antinematodal activity against Bursaphelenchus xylophilus and Caenorhabditis elegans with IC50 values of 98.17μg/mL and 74.62μg/mL, respectively. This work is the first report on alternariol 9-methyl ether and its biological activities from the endophytic fungus Alternaria sp. Samif01 derived from S. miltiorrhiza Bunge. The results indicate the potential of Alternaria sp. Samif01 as a source of alternariol 9-methyl ether and also support that alternariol 9-methyl ether is a natural compound with high potential bioactivity against microorganisms.

  12. Effects of meteorological factors on the levels of Alternaria spores on a potato crop

    Science.gov (United States)

    Escuredo, Olga; Seijo, Maria Carmen; Fernández-González, Maria; Iglesias, Isabel

    2011-03-01

    Alternaria solani Soraeur produces early blight in Solanum tuberosum L., leading to significant agricultural losses. The current study was carried out on the extensive potato crop situated in north-western of Spain during 2007, 2008 and 2009. In this area potato crops are the most important source of income. In this work we used a Hirst-type volumetric spore-trap for the aerobiological monitoring of Alternaria spores. The highest spore concentrations were recorded during the 2009 cycle (10,555 spores), and the lowest concentrations were recorded during the 2008 cycle (5,471 spores). Over the 3 years of study, the highest concentrations were registered during the last stage of the crop. The aim of the study was to observe the influence of meteorological factors on the concentration of Alternaria spores, which can lead to serious infection and early blight. Prediction of the stages during which a crop is particularly vulnerable to infection allows for adjustment of the application of fungicide and is of environmental and agricultural importance. For this reason, we tested three models (P-Days, DD and IWP) to predict the first treatment and decrease the negative effect that these spores have on potato crops. The parameter that showed the most significant correlation with spore concentrations was minimum temperature. We used ARIMA (autoregressive integrated model of running mean) time-series models to determine the forecast. We considered weather data as predictor variables and the concentration of spores on the previous day as the fixed variable.

  13. Plant extracts and essential oils on the control of Alternaria alternata , Alternaria dauci and on the germination and emergence of carrot seeds ( Daucus carota L.

    Directory of Open Access Journals (Sweden)

    Cristina Batista de Lima

    2016-05-01

    Full Text Available ABSTRACT: The present study aims to investigate garlic, pepper and coriander plant extract as well as neem and orange peel essential oil effective ness to control Alternaria alternata and Alternaria dauci and their efficiency during carrot seeds germination and emergence. A completely randomized design was used in three different experiments. The first experiment evaluated the effect of plant extracts and essential oils on the incidence of A. alternata and A. dauci . It was done by means of a factorial design applied to five treatments (garlic, pepper, coriander, and neem and orange peel essential oils at three concentrations (10, 20 and 30%.They also evaluated the controls untreated and with fungicide (Thiram.The second experiment evaluated the effect of the treatment at30% concentration on the germination and emergence of seedlings assessed on trays, and in the third experiment, the presence of A. alternata and A. dauci on the pericarp, endosperm and on the embryo. A. alternata showed higher incidence than A. dauci. The garlic extract and the orange essential oil showed the potential to control A. dauci and A. alternata, because their lower concentrations were able to sufficiently reduce the incidence of these fungi and because they do not affect carrot seeds germination and emergence. A. alternata conidia were found on the embryo (8%, pericarp (17% and endosperm (31%.

  14. 2004 SWFWMD Citrus County Lidar Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This metadata record describes the ortho & LIDAR mapping of Citrus County, FL. The mapping consists of LIDAR data collection, contour generation, and production...

  15. The aconitate hydratase family from Citrus

    Directory of Open Access Journals (Sweden)

    Cercos Manuel

    2010-10-01

    Full Text Available Abstract Background Research on citrus fruit ripening has received considerable attention because of the importance of citrus fruits for the human diet. Organic acids are among the main determinants of taste and organoleptic quality of fruits and hence the control of fruit acidity loss has a strong economical relevance. In citrus, organic acids accumulate in the juice sac cells of developing fruits and are catabolized thereafter during ripening. Aconitase, that transforms citrate to isocitrate, is the first step of citric acid catabolism and a major component of the citrate utilization machinery. In this work, the citrus aconitase gene family was first characterized and a phylogenetic analysis was then carried out in order to understand the evolutionary history of this family in plants. Gene expression analyses of the citrus aconitase family were subsequently performed in several acidic and acidless genotypes to elucidate their involvement in acid homeostasis. Results Analysis of 460,000 citrus ESTs, followed by sequencing of complete cDNA clones, identified in citrus 3 transcription units coding for putatively active aconitate hydratase proteins, named as CcAco1, CcAco2 and CcAco3. A phylogenetic study carried on the Aco family in 14 plant species, shows the presence of 5 Aco subfamilies, and that the ancestor of monocot and dicot species shared at least one Aco gene. Real-time RT-PCR expression analyses of the three aconitase citrus genes were performed in pulp tissues along fruit development in acidic and acidless citrus varieties such as mandarins, oranges and lemons. While CcAco3 expression was always low, CcAco1 and CcAco2 genes were generally induced during the rapid phase of fruit growth along with the maximum in acidity and the beginning of the acid reduction. Two exceptions to this general pattern were found: 1 Clemenules mandarin failed inducing CcAco2 although acid levels were rapidly reduced; and 2 the acidless "Sucreña" orange

  16. A transcriptomic approach highlights induction of secondary metabolism in citrus fruit in response to Penicillium digitatum infection

    Directory of Open Access Journals (Sweden)

    González-Candelas Luis

    2010-08-01

    Full Text Available Abstract Background Postharvest losses of citrus fruit due to green mold decay, caused by the fungus Penicillium digitaum, have a considerable economic impact. However, little is known about the molecular processes underlying the response of citrus fruit to P. digitatum. Results Here we describe the construction of a subtracted cDNA library enriched in citrus genes preferentially expressed in response to pathogen infection followed by cDNA macroarray hybridization to investigate gene expression during the early stages of colonization of the fruit's peel by P. digitatum. Sequence annotation of clones from the subtracted cDNA library revealed that induction of secondary and amino acid metabolisms constitutes the major response of citrus fruits to P. digitatum infection. Macroarray hybridization analysis was conducted with RNA from either control, wounded, ethylene treated or P. digitatum infected fruit. Results indicate an extensive overlap in the response triggered by the three treatments, but also demonstrated specific patterns of gene expression in response to each stimulus. Collectively our data indicate a significant presence of isoprenoid, alkaloid and phenylpropanoid biosynthetic genes in the transcriptomic response of citrus fruits to P. digitatum infection. About half of the genes that are up-regulated in response to pathogen infection are also induced by ethylene, but many examples of ethylene-independent gene regulation were also found. Two notable examples of this regulation pattern are the genes showing homology to a caffeine synthase and a berberine bridge enzyme, two proteins involved in alkaloid biosynthesis, which are among the most induced genes upon P. digitatum infection but are not responsive to ethylene. Conclusions This study provided the first global picture of the gene expression changes in citrus fruit in response to P. digitatum infection, emphasizing differences and commonalities with those triggered by wounding or

  17. Antihyperlipidemic effects of Citrus sinensis, Citrus paradisi, and their combinations

    Directory of Open Access Journals (Sweden)

    Neelam Mallick

    2016-01-01

    Full Text Available Objective: Hyperlipidemia, extensively contributes in the progression of coronary heart diseases and atherosclerosis, but may be managed through alterations in the nutritional pattern. Several studies show that diet rich in polyphenols and antioxidants have antiatherogenic effects. Citrus sinensis and Citrus paradisi are widely known for health benefits and have found to produce antioxidant, anti-inflammatory, and hypolipidemic effects, hence current research was planned to determine the hypolipidemic effects of C. sinensis and C. paradisi in rats receiving diet rich in cholesterol. Materials and Methods: All rats were divided into 11 groups each comprising 10 animals: Normal control group and hyperlipidemic control. C. sinensis treated three groups, C. paradisi treated three groups, C. sinensis and C. paradisi combination treated two groups, and group treated atorvastatin. All rats in the respective groups were treated orally with sterile water, juices, and standard drug for 8 weeks and lipid profile was estimated at the end of dosing. Results: Cholesterol, triglycerides (TGs, and low-density lipoprotein (LDL were decreased at all the three doses of C. sinensis and C. paradisi but rise in high-density lipoprotein (HDL was only significant at 8 ml/kg, and 0.3 ml/kg, respectively. Animals received the combination doses of C. sinensis and C. paradisi also showed a highly significant fall in cholesterol, LDL, and TGs, however HDL level was significantly elevated by SPJ-2 combination. Conclusion: Results suggest that C. sinensis and C. paradisi possess antihyperlipidemic activity due to phytochemicals and other essential nutrients, hence may serve as cardioprotective by preventing thrombosis.

  18. The role of meteorological factors in determining the annual variation of Alternaria and Cladosporium spores in the atmosphere of Palencia, 1990 1992

    Science.gov (United States)

    Herrero, B.; Fombella-Blanco, M. A.; Fernández-González, D.; Valencia-Barrera, R. M.

    1996-09-01

    A study was made of the daily content of Alternaria and Cladosporium spores in the atmosphere in Palencia city (Spain) for three consecutive years 1990 1992. Alternaria and Cladosporium represented 55% of the total identified spores, presenting an annual distributional pattern of which the maximum values were reached in summer. Multiple regression analyses showed a positive correlation between minimum temperature and Cladosporium spore concentrations, while for Alternaria there was a positive correlation with maximum temperature and a negative correlation with precipitation. Duncan's multiple range test among means of Alternaria data indicated that winds coming from a northeasterly direction were associated with significantly higher concentrations the spores.

  19. Small RNA profiling reveals phosphorus deficiency as a contributing factor in symptom expression for citrus huanglongbing disease.

    Science.gov (United States)

    Zhao, Hongwei; Sun, Ruobai; Albrecht, Ute; Padmanabhan, Chellappan; Wang, Airong; Coffey, Michael D; Girke, Thomas; Wang, Zonghua; Close, Timothy J; Roose, Mikeal; Yokomi, Raymond K; Folimonova, Svetlana; Vidalakis, Georgios; Rouse, Robert; Bowman, Kim D; Jin, Hailing

    2013-03-01

    Huanglongbing (HLB) is a devastating citrus disease that is associated with bacteria of the genus 'Candidatus Liberibacter' (Ca. L.). Powerful diagnostic tools and management strategies are desired to control HLB. Host small RNAs (sRNA) play a vital role in regulating host responses to pathogen infection and are used as early diagnostic markers for many human diseases, including cancers. To determine whether citrus sRNAs regulate host responses to HLB, sRNAs were profiled from Citrus sinensis 10 and 14 weeks post grafting with Ca. L. asiaticus (Las)-positive or healthy tissue. Ten new microRNAs (miRNAs), 76 conserved miRNAs, and many small interfering RNAs (siRNAs) were discovered. Several miRNAs and siRNAs were highly induced by Las infection, and can be potentially developed into early diagnosis markers of HLB. miR399, which is induced by phosphorus starvation in other plant species, was induced specifically by infection of Las but not Spiroplasma citri that causes citrus stubborn-a disease with symptoms similar to HLB. We found a 35% reduction of phosphorus in Las-positive citrus trees compared to healthy trees. Applying phosphorus oxyanion solutions to HLB-positive sweet orange trees reduced HLB symptom severity and significantly improved fruit production during a 3-year field trial in south-west Florida. Our molecular, physiological, and field data suggest that phosphorus deficiency is linked to HLB disease symptomology.

  20. Nine Pathogenic Fungi of Waterhyacinth Isolated in China

    Institute of Scientific and Technical Information of China (English)

    DING Yi; ZHAO Nan; CHU Jian-jun

    2008-01-01

    The native pathogens of waterhyacinth in China, were studied and compared on pathogenicity by Koch's postulate. Nine pathogenic fungi, YBH, YBB, YB, YYX, YY, YBA1, YBA2, YBA3 and YYB12, were isolated from diseased waterhyacinth plants, and collected from Zhejiang province and Shanghai. According to cultural characteristics, the nine isolates were preliminarily identified. Isolates YBH and YBB were Collectotrichum sp.:YB, YYX and YY were placed in fungi imperfecti:the isolates YBA1, YBA2, YBA3 and YYB12 were Alternaria sp. The isolate YBH was the highly virulent with a disease index (DI) of 65.28% after one month inoculation. The isolate YBA3 was equily virulent, with the disease index of 67% after 7 day introduction. These two pathogens appear to have the potential as biocontrol agents and they deserve further study.

  1. Genes associated with hypersensitive response (HR in the citrus EST database (CitEST

    Directory of Open Access Journals (Sweden)

    Simone Guidetti-Gonzalez

    2007-01-01

    Full Text Available Plants are continuously exposed to pathogen attack, but successful infection is rare because they protect themselves against pathogens using a wide range of response mechanisms. One of them is the hypersensitive response (HR, which is a form of cell death often associated with plant resistance to pathogen infection to prevent the spreadsebpg@cnpq.br sebpg@cnpq.br of the potential pathogen from infected to uninfected tissues. Cell death is activated by recognition of pathogen-derived molecules by the resistance (R gene products, and is associated with the massive accumulation of reactive oxygen species (ROS, salicylic acid (SA, and other pro-death signals such as nitric oxide (NO. The analysis of the citrus EST (CitEST database revealed the presence of putative genes likely to be involved in HR through their products, like metacaspases, lipoxygenases, phospholipases, pathogenesis-related proteins, glutathione transferases/peroxidases, enzymes involved in the phenylpropanoid pathway and in the formation and detoxification of ROS, as well as those involved in the formation and regulation of ion channels, SA and NO. By analysis of the EST database of Citrus, it was possible to identify several putative genes that code for key enzymes involved in HR triggering and also in plant defense against biotic and abiotic stress.

  2. Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

    Science.gov (United States)

    Manhas, Rajesh K.; Kaur, Talwinder

    2016-01-01

    Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75–80%) and vigor index (1167–1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers. PMID:28018402

  3. Biocontrol Potential of Streptomyces hydrogenans strain DH16 Towards Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

    Directory of Open Access Journals (Sweden)

    Rajesh Kumari Manhas

    2016-12-01

    Full Text Available Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v of Streptomyces hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10% and streptomycete cells significantly improved seed germination (75-80% and vigour index (1167-1538. Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.

  4. Biocontrol Potential of Streptomyces hydrogenans Strain DH16 toward Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus.

    Science.gov (United States)

    Manhas, Rajesh K; Kaur, Talwinder

    2016-01-01

    Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v) of S. hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10%) and streptomycete cells significantly improved seed germination (75-80%) and vigor index (1167-1538). Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.

  5. First report of Phyllosticta citricarpa and description of two new species, P. paracapitalensis and P. paracitricarpa, from citrus in Europe.

    Science.gov (United States)

    Guarnaccia, V; Groenewald, J Z; Li, H; Glienke, C; Carstens, E; Hattingh, V; Fourie, P H; Crous, P W

    2017-06-01

    The genus Phyllosticta occurs worldwide, and contains numerous plant pathogenic, endophytic and saprobic species. Phyllosticta citricarpa is the causal agent of Citrus Black Spot disease (CBS), affecting fruits and leaves of several citrus hosts (Rutaceae), and can also be isolated from asymptomatic citrus tissues. Citrus Black Spot occurs in citrus-growing regions with warm summer rainfall climates, but is absent in countries of the European Union (EU). Phyllosticta capitalensis is morphologically similar to P. citricarpa, but is a non-pathogenic endophyte, commonly isolated from citrus leaves and fruits and a wide range of other hosts, and is known to occur in Europe. To determine which Phyllosticta spp. occur within citrus growing regions of EU countries, several surveys were conducted (2015-2017) in the major citrus production areas of Greece, Italy, Malta, Portugal and Spain to collect both living plant material and leaf litter in commercial nurseries, orchards, gardens, backyards and plant collections. A total of 64 Phyllosticta isolates were obtained from citrus in Europe, of which 52 were included in a multi-locus (ITS, actA, tef1, gapdh, LSU and rpb2 genes) DNA dataset. Two isolates from Florida (USA), three isolates from China, and several reference strains from Australia, South Africa and South America were included in the overall 99 isolate dataset. Based on the data obtained, two known species were identified, namely P. capitalensis (from asymptomatic living leaves of Citrus spp.) in Greece, Italy, Malta, Portugal and Spain, and P. citricarpa (from leaf litter of C. sinensis and C. limon) in Italy, Malta and Portugal. Moreover, two new species were described, namely P. paracapitalensis (from asymptomatic living leaves of Citrus spp.) in Italy and Spain, and P. paracitricarpa (from leaf litter of C. limon) in Greece. On a genotypic level, isolates of P. citricarpa populations from Italy and Malta (MAT1-2-1) represented a single clone, and those

  6. 78 FR 41259 - Importation of Fresh Citrus Fruit From Uruguay, Including Citrus

    Science.gov (United States)

    2013-07-10

    ... that this argument is invalid due to the year-round marketing of citrus harvested domestically. We made... variety. Total citrus production in Uruguay in 2011 was 270,367 metric tons, which is less than 3 percent... metric tons, respectively, which is less than 3.2 percent of U.S. production and 1 percent of total...

  7. H NMR analyses of Citrus macrophylla subjected to Asian citrus psyllid (Diaphorina citri Kuwayama) feeding

    Science.gov (United States)

    The Asian citrus psyllid (ACP) is a phloem feeding insect that can host and transmit the bacterium Candidatus Liberibacter asiaticus (CLas), which is the putative causative agent of the economically important citrus disease, Huanglongbing (HLB). ACP are widespread in Florida, and are spreading in Ca...

  8. Interrelations between citrus rust mite, Hirsutella thompsonii and greasy spot on citrus in Surinam

    NARCIS (Netherlands)

    Brussel, van E.W.

    1975-01-01

    Counts of citrus rust mite (Phyllocoptruta oleivora (Ashm.)) on leaves and fruit of citrus rose to a peak in the two dry seasons, the build up taking 4-5 weeks. It then decreased partly through infection by the entomogenous fungus Hirsutellathompsonii Fisher and partly through a decline in feed qual

  9. Detection of non-typhoid Salmonella infection by citrus and citrus extracts in Lao PDR

    Institute of Scientific and Technical Information of China (English)

    Yutaka Midorikawa; Satoshi Nakamura; Rattanaphone Phetsouvanh; Manivanh Vongsouvaht; Kaoru Midorikawa

    2010-01-01

    Objective: To know the current state of non-typhoid Salmonella infection in Laos. To examine the usefulness of new screening methods for Salmonella using citrus. Methods: Non-typhoidSalmonella infection of person in Lao PDR was studied in this research (2004-2009). The site was Vientiane capital city in 2004. Research from rural villages locating suburb of Vientiane during 2005-2008 was carried out. Rural villages in Attapu province where ethnic minorities were living was searched for this study in 2009. During this research, to detect Salmonella strain, a new method using citrus and citrus extract named MY phenomenon that observing black ring (MIDO ring) on DHL agar was tried. The slice lemon and lime were used for this trial in 2004. After 2005, disk of ascorbic acid and citric acid were used for the device instead of citrus fruits itself. Results: During this research, 65 of 272 human samples (23.9%) were infected with non-typhoid Salmonella. Conclusions: During this study, the method using citrus and citrus extracts was accepted for the detection of Salmonella. This study shows that with citrus and citrus extract, detection of Salmonella is possible using only DHL media. Results suggest that infectious rate of non-typhoid Salmonella was high.

  10. Sensitization to Alternaria and Cladosporium in patients with respiratory allergy and outdoor counts of mold spores in Ankara atmosphere, Turkey.

    Science.gov (United States)

    Bavbek, Sevim; Erkekol, Ferda Oner; Ceter, Talip; Mungan, Dilşad; Ozer, Faruk; Pinar, Münevver; Misirligil, Zeynep

    2006-08-01

    Sensitization to Alternaria and Cladosporium has been reported to be 3% to 30% in European countries. However, in Turkey, there is limited data about the prevalence of sensitization to these molds and the intensity of the two mold spores in Ankara atmosphere. This study was designed to evaluate the sensitization to Alternaria and Cladosporium in patients with respiratory allergy in Ankara and also the concentration of the two molds in Ankara atmosphere. Allergic rhinitis and asthma patients living in Ankara were included in the study. Demographic and diagnostic data of the patients were recorded. A skin prick test with extracts supplied by three different laboratories was used to evaluate the sensitization to Alternaria and Cladosporium. Mold spores were measured using a Burkard 7-day recording volumetric spore trap in Ankara atmosphere during a year. Overall sensitization to the two molds was found to be 14.8%, and isolated Alternaria or Cladosporiumsensitization was 3%. Considering the positive reaction to at least one of the three suppliers, the sensitization rate was 11.9% and 8.1% for Alternaria and Cladosporium, respectively. Cochran's Q homogenization test demonstrated that the positive and negative reaction were not homogeneous among three laboratories. The total number of mold spores in Ankara atmosphere was 429,264 spores/m3 of which 75.5% and 6% were constituted by Cladosporium and Alternaria, respectively. The prevalence of Cladosporium and Alternaria sensitization in respiratory allergy patients is quite similar to European countries; however, our data indicate that commercial mold extracts should be standardized to establish the real sensitization rates. Additionally, considering the great numbers of these mold spores in Ankara atmosphere, long-term follow-up studies are needed to evaluate the relationship between the mold load and sensitization patterns.

  11. The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

    Directory of Open Access Journals (Sweden)

    João Lúcio Azevedo

    Full Text Available Abstract The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC.

  12. Genetic Diversity and Global Distribution of Citrus tristeza virus (CTV) Strains

    Institute of Scientific and Technical Information of China (English)

    Wu Xiao-yun; Cheng Xiao-fei; Luo Lu; Wu Xiao-xia

    2012-01-01

    Citrus tristeza virus (CTV), the most devastating viral pathogen in citrus, causes tremendous economic losses to citrus industry worldwide. The CTV isolates exhibit variable pathogenicities on their hosts indicating a mixed population of the CTV in nature. Several fragments within the CTV genome have been used for studying the genetic diversity of the CTV, however, the best region for rapid the CTV strain differentiation is still absent at present. In present study, a systemic analysis was carried out to evaluate the best region within the CTV genome for rapid CTV strain differentiation. Results of our study showed that the major coat protein (CP) coding region was the best region for this purpose. Using pair-wise distance frequency distribution plot, a reasonable genetic distance cut-off value was set for the CTV CP gene for the CTV strain differentiation. Using this criterion, eight CTV strains, including seven well characterized and a new strain, were successfully differentiated using 537 CTV isolates reported from 38 countries. The global strain distribution pattern was then determined and discussed. Our results also provided a new insight into the evolution and spreading of the virus, as well as the information for developing proper disease management strategy.

  13. Rootstock-scion interaction affecting citrus response to CTV infection: a proteomic view.

    Science.gov (United States)

    Laino, Paolo; Russo, Maria P; Guardo, Maria; Reforgiato-Recupero, Giuseppe; Valè, Giampiero; Cattivelli, Luigi; Moliterni, Vita M C

    2016-04-01

    Citrus tristeza virus (CTV) is the causal agent of various diseases with dramatic effects on citrus crops worldwide. Most Citrus species, grown on their own roots, are symptomless hosts for many CTV isolates. However, depending on different scion-rootstock combination, CTV infection should result in distinct syndromes, being 'tristeza' the more severe one, leading to a complete decline of the susceptible plants in a few weeks. Transcriptomic analyses revealed several genes involved either in defense response, or systemic acquired resistance, as well as transcription factors and components of the phosphorylation cascades, to be differentially regulated during CTV infection in Citrus aurantifolia species. To date little is known about the molecular mechanism of this host-pathogen interaction, and about the rootstock effect on citrus response to CTV infection. In this work, the response to CTV infection has been investigated in tolerant and susceptible scion-rootstock combinations by two-dimensional gel electrophoresis (2DE). A total of 125 protein spots have been found to be differently accumulated and/or phosphorylated between the two rootstock combinations. Downregulation in tolerant plants upon CTV infection was detected for proteins involved in reactive oxygen species (ROS) scavenging and defense response, suggesting a probable acclimation response able to minimize the systemic effects of virus infection. Some of these proteins resulted to be modulated also in absence of virus infection, revealing a rootstock effect on scion proteome modulation. Moreover, the phospho-modulation of proteins involved in ROS scavenging and defense response, further supports their involvement either in scion-rootstock crosstalk or in the establishment of tolerance/susceptibility to CTV infection. © 2015 Scandinavian Plant Physiology Society.

  14. Resposta diferencial das cultivares de algodoeiro a Alternaria macrospora Differential response of cotton cultivars to Alternaria macrospora

    Directory of Open Access Journals (Sweden)

    Yeshwant Ramchandra Mehta

    2006-06-01

    Full Text Available Estudou-se a resposta diferencial de 32 cultivares comerciais do algodoeiro a A. macrospora em casa de vegetação. A inoculação foi realizada em plântulas de 20-25 dias de idade com 25 repetições, utilizando-se o delineamento experimental de blocos ao acaso. As cultivares foram agrupadas através de análise de Scott & Knott. Resistência completa não foi encontrada, sendo que todas as cultivares foram suscetíveis. Houve diferença entre reação de plantas da mesma cultivar. Não obstante, quando algumas plantas das cvs. BRS Antares e Fibermax 986, que mostraram resistência, foram inoculadas com mistura de nove isolados escolhidos ao acaso, as mesmas mantiveram sua resistência a esta mistura. Trabalhos futuros deverão ser realizados para encontrar fontes de resistência a este patógeno em outras espécies de Gossypium.The differential response of 32 commercial cotton cultivars to A. macrospora was studied under greenhouse conditions. Twenty to twentyfive days old plants were inoculated in 25 repetitions in a randomized block design. The cultivars were grouped using the Scott & Knott analysis. Complete resistance was not found and all cultivars were susceptible to the pathogen. Differential reaction within the plants of the same cultivar was observed. However, when some resistant plants of cultivars BRS Antares and Fibermax 986 were inoculated using a mixture of nine randomly selected isolates of A. macrospora, the plants maintained their resistance. Further research is necessary to find sources of resistance to this pathogen in other species of Gossypium.

  15. 贡柑黑腐病发生规律研究%Study on Occurrence Regularity of Black Rot of Gonggan Citrus

    Institute of Scientific and Technical Information of China (English)

    邓明学; 覃旭; 阳庭密; 谭有龙; 潘振兴; 谢艳芳

    2012-01-01

    The occurrence regularity of black rot of gonggan citrus was studied using artificial inoculation and field investigation methods in 2011-2012. The results showed that the pathogen could invade plant from the surface of healthy leaves without wound although it was easier for the pathogen to invade from the wound. By artificial inoculation, Gonggan and Murcott were the most susceptible cultivars followed by Ponkan and Nanfengmiju. The new buds of mashuiju, shatangju and satsuma mandarin were occasionally infected when there were wounds and continuous rain. Orange, pomelo, lemon and kumquat were resistant varieties. In the field, Gonggan and Murcott were the most susceptible varieties, followed by Nanfengmiju and Ponkan, and there was no infection on Mashuiju, shatangju and satsuma mandarin. Generally, young shoots and young fruits were susceptible, and mature leaves and mature fruits were less susceptible. Heavy infections occurred mostly on the young trees, fruiting trees and trees with a lot of young shoots. Spore germination requires high humidity, and therefore, rainy, high temperature and high humidity conditions facilitate the infection and spread of the disease. Summer shoots were the most severely infected, followed by spring shoots and young fruits. Autumn shoots were the least infected. Symptoms appeared within 1~3 days of infection by artificial inoculation of the spore under 15~30 ℃ and rainy conditions. The pathogen invaded rapidly along the veins, making it difficult to control the disease.%2011-2012年采用盆栽苗人工接种和田间调查相结合的方法,研究了贡柑产区近年为害严重的黑腐病(病原菌为Alternaria citri)的发生规律.结果表明:在人工接种条件下,其病原菌可以从没有伤口的叶面侵入,但更易从伤口入侵;贡柑和默科特桔最感病,其次是椪柑和南丰蜜桔,在有伤口和连续下雨的条件下马水桔、沙糖桔和温州蜜柑的嫩芽也偶被感染,橙类、柚类、柠

  16. Comparative evaluation of biochemical changes in tomato (Lycopersicon esculentum Mill. infected by Alternaria alternata and its toxic metabolites (TeA, AOH and AME

    Directory of Open Access Journals (Sweden)

    Mukesh Meena

    2016-09-01

    Full Text Available In the present study, we have evaluated the comparative biochemical defense response generated against Alternaria alternata and its purified toxins viz. alternariol (AOH, alternariol monomethyl ether (AME and tenuazonic acid (TeA. The necrotic lesions developed due to treatment with toxins were almost similar as those produced by pathogen, indicating the crucial role of these toxins in plant pathogenesis. An oxidative burst reaction characterized by the rapid and transient production of a large amount of reactive oxygen species (ROS occurs following the pathogen infection/toxin exposure. The maximum concentration of H2O2 produced was reported in pathogen infected samples (22.2-fold at 24 h post inoculation followed by TeA (18.2-fold, AOH (15.9-fold, and AME (14.1-fold in treated tissues. DAB staining predicted the possible sites of H2O2 accumulation while the extent of cell death were measured by Evans blue dye. The extent of lipid peroxidation and MDA content was higher (15.8-fold at 48 h in the sample of inoculated leaves of pathogen, when compared to control. The cellular damages were observed as increased MDA content and reduced chlorophyll. The activities of antioxidative defense enzymes increased in both pathogen infected as well as toxin treated samples. SOD, activity was 5.9- fold higher at 72 h post inoculation in leaves followed by TeA (5.0-fold, AOH (4.1-fold and AME (2.3-fold treated leaves than control. Catalase activity was found to be increased upto 48 h post inoculation and maximum in pathogen challenged samples followed by other toxins. The native PAGE results showed the variations in the intensities of isozyme (SOD and CAT bands in the pathogen infected and toxin treated samples. APx and GR activities followed the similar trend to scavenge the excess H2O2. The reduction in CAT activities after 48 h post inoculation demonstrate that the biochemical defense programming shown by the host against the pathogen is not well efficient

  17. Mathematical modeling of citrus groves infected by huanglongbing.

    Science.gov (United States)

    Jacobsen, Karly; Stupiansky, Jillian; Pilyugin, Sergei S

    2013-06-01

    Huanglongbing (citrus greening) is a bacterial disease that is significantly impacting the citrus industry in Florida and poses a risk to the remaining citrus-producing regions of the United States. A mathematical model of a grove infected by citrus greening is developed. An equilibrium stability analysis is presented. The basic reproductive number and its relation to the persistence of the disease is discussed. A numerical study is performed to illustrate the theoretical findings.

  18. Shedding light on the role of photosynthesis in pathogen colonization and host defense

    KAUST Repository

    Garavaglia, Betiana S.

    2010-09-01

    The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (DeltaXacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with DeltaXacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that DeltaXacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

  19. Phenylethanol promotes adhesion and biofilm formation of the antagonistic yeast Kloeckera apiculata for the control of blue mold on citrus.

    Science.gov (United States)

    Pu, Liu; Jingfan, Fang; Kai, Chen; Chao-an, Long; Yunjiang, Cheng

    2014-06-01

    The yeast Kloeckera apiculata strain 34-9 is an antagonist with biological control activity against postharvest diseases of citrus fruit. In a previous study it was demonstrated that K. apiculata produced the aromatic alcohol phenylethanol. In the present study, we found that K. apiculata was able to form biofilm on citrus fruit and embed in an extracellular matrix, which created a mechanical barrier interposed between the wound surface and pathogen. As a quorum-sensing molecule, phenylethanol can promote the formation of filaments by K. apiculata in potato dextrose agar medium, whereas on the citrus fruit, the antagonist remains as yeast after being treated with the same concentration of phenylethanol. It only induced K. apiculata to adhere and form biofilm. Following genome-wide computational and experimental identification of the possible genes associated with K. apiculata adhesion, we identified nine genes possibly involved in triggering yeast adhesion. Six of these genes were significantly induced after phenylethanol stress treatment. This study provides a new model system of the biology of the antagonist-pathogen interactions that occur in the antagonistic yeast K. apiculata for the control of blue mold on citrus caused by Penicillium italicum.

  20. A graft-based chemotherapy method for screening effective molecules and rescuing huanglongbing-affected citrus plants.

    Science.gov (United States)

    Zhang, Muqing; Powell, Charles A; Guo, Ying; Doud, Melissa S; Duan, Yongping

    2012-06-01

    Huanglongbing (HLB) is the most devastating disease of citrus. The global citrus industry is in urgent need of effective chemical treatments for HLB control because of its rapid spreading worldwide. Due to the fastidious nature of the pathogens, and the poor permissibility of citrus leaf surfaces, effective screening of chemicals for the HLB control can be challenging. In this study, we developed a graft-based chemotherapy method to rapidly screen potential HLB-controlling chemical compounds. In addition, we improved transmission efficiency by using the best HLB-affected scion-rootstock combination, and demonstrated the HLB bacterial titer was the critical factor in transmission. The HLB-affected lemon scions had a high titer of HLB bacterium, survival rate (83.3%), and pathogen transmission rate (59.9%). Trifoliate, a widely used commercial rootstock, had the highest survival rate (>70.0%) compared with grapefruit (52.6%) and sour orange (50.4%). Using this method, we confirmed a mixture of penicillin and streptomycin was the most effective compounds in eliminating the HLB bacterium from the HLB-affected scions, and in successfully rescuing severely HLB-affected citrus germplasms. These findings are useful not only for chemical treatments but also for graft-based transmission studies in HLB and other Liberibacter diseases.

  1. Closely-related Xanthomonas citri subsp. citri isolates trigger distinct histological and transcriptional responses in Citrus limon

    Directory of Open Access Journals (Sweden)

    Ingrid Georgina Orce

    Full Text Available ABSTRACT Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc, has an important economic impact on the citrus industry. Extensive information is available about the disease but, nevertheless, the study of plant-pathogen interactions could provide new information in the understanding of citrus canker disease. A new isolate has been identified, Xcc AT, which has a high genetic similarity (> 90 % to the virulent Xcc T strain based on genetic clustering analyses of the rep-PCR fingerprinting patterns, but it does not produce cankerous lesions in Citrus limon. In this study, we compared C. limon responses to Xcc AT and to the virulent Xcc T strain at both histological and transcriptional levels. Histologically, leaves inoculated with Xcc AT exhibited neither a typical disordering of the spongy mesophyll, nor a swelling of epidermis. A particular content (undetermined was also found in mesophyll cells near the stomata, together with increased starch accumulation. The transcriptomic profiles were compared by cDNA-AFLP technique. A total of 121 fragments derived from transcript (TDF were either specifically induced or repressed by the isolates, and 62 were sequenced. Analysis of global expression identified different classes of genes known to be involved in plant-pathogen interactions. This study constitutes the first approach of the specific interaction between the avirulent Xcc AT isolate and C. limon.

  2. Antifungal activity of food additives in vitro and as ingredients of hydroxypropyl methylcellulose-lipid edible coatings against Botrytis cinerea and Alternaria alternata on cherry tomato fruit.

    Science.gov (United States)

    Fagundes, Cristiane; Pérez-Gago, María B; Monteiro, Alcilene R; Palou, Lluís

    2013-09-16

    The antifungal activity of food additives or 'generally recognized as safe' (GRAS) compounds was tested in vitro against Botrytis cinerea and Alternaria alternata. Radial mycelial growth of each pathogen was measured in PDA Petri dishes amended with food preservatives at 0.2, 1.0, or 2.0% (v/v) after 3, 5, and 7 days of incubation at 25 °C. Selected additives and concentrations were tested as antifungal ingredients of hydroxypropyl methylcellulose (HPMC)-lipid edible coatings. The curative activity of stable coatings was tested in in vivo experiments. Cherry tomatoes were artificially inoculated with the pathogens, coated by immersion about 24 h later, and incubated at 20 °C and 90% RH. Disease incidence and severity (lesion diameter) were determined after 6, 10, and 15 days of incubation and the 'area under the disease progress stairs' (AUDPS) was calculated. In general, HPMC-lipid antifungal coatings controlled black spot caused by A. alternata more effectively than gray mold caused by B. cinerea. Overall, the best results for reduction of gray mold on cherry tomato fruit were obtained with coatings containing 2.0% of potassium carbonate, ammonium phosphate, potassium bicarbonate, or ammonium carbonate, while 2.0% sodium methylparaben, sodium ethylparaben, and sodium propylparaben were the best ingredients for coatings against black rot.

  3. First report of citrus leprosis virus nuclear type in Colombia

    Science.gov (United States)

    Citrus leprosis is a difficult viral disease causing significant damage to citrus fruit in South America and Central America. The disease is marked by dramatic lesions on fruit, leaves and stems resulting in unmarketable product. Citrus leprosis virus cytoplasmic types (CiLV-C and CiLV-C2) wer edete...

  4. Wavelength and polarization affect phototaxis of the Asian citrus psyllid

    Science.gov (United States)

    The Asian citrus psyllid, D. citri, is a primary pest for citrus production due to its status as a vector of the citrus disease, huanglongbing. We investigated phototactic behavior of D. citri to evaluate effects of light of specific wavelength or polarization using a horizontal bioassay arena. Wave...

  5. Current California Drought: Impact on Citrus Trees and Potential Mitigation

    Science.gov (United States)

    California is in another cycle of extended drought. The article reviews and discusses likely impact of the current drought on citrus growers and potential mitigation techniques. Citrus physiological responses to water stress is briefly reviewed. The direct impact of drought on citrus is reduced frui...

  6. Biological Indexing of Graft Transmissible Diseases of Citrus

    Science.gov (United States)

    Biological indexing for the detection of graft transmissible diseases of citrus is essential for maintaining a citrus certification program. Many of the graft transmissible diseases of citrus are harbored as latent infections in the scions, but when propagated on a susceptible rootstock that allow...

  7. Genome wide selection in Citrus breeding.

    Science.gov (United States)

    Gois, I B; Borém, A; Cristofani-Yaly, M; de Resende, M D V; Azevedo, C F; Bastianel, M; Novelli, V M; Machado, M A

    2016-10-17

    Genome wide selection (GWS) is essential for the genetic improvement of perennial species such as Citrus because of its ability to increase gain per unit time and to enable the efficient selection of characteristics with low heritability. This study assessed GWS efficiency in a population of Citrus and compared it with selection based on phenotypic data. A total of 180 individual trees from a cross between Pera sweet orange (Citrus sinensis Osbeck) and Murcott tangor (Citrus sinensis Osbeck x Citrus reticulata Blanco) were evaluated for 10 characteristics related to fruit quality. The hybrids were genotyped using 5287 DArT_seq(TM) (diversity arrays technology) molecular markers and their effects on phenotypes were predicted using the random regression - best linear unbiased predictor (rr-BLUP) method. The predictive ability, prediction bias, and accuracy of GWS were estimated to verify its effectiveness for phenotype prediction. The proportion of genetic variance explained by the markers was also computed. The heritability of the traits, as determined by markers, was 16-28%. The predictive ability of these markers ranged from 0.53 to 0.64, and the regression coefficients between predicted and observed phenotypes were close to unity. Over 35% of the genetic variance was accounted for by the markers. Accuracy estimates with GWS were lower than those obtained by phenotypic analysis; however, GWS was superior in terms of genetic gain per unit time. Thus, GWS may be useful for Citrus breeding as it can predict phenotypes early and accurately, and reduce the length of the selection cycle. This study demonstrates the feasibility of genomic selection in Citrus.

  8. Study on citrus response to huanglongbing highlights a down-regulation of defense-related proteins in lemon plants upon 'Ca. Liberibacter asiaticus' infection.

    Science.gov (United States)

    Nwugo, Chika C; Duan, Yongping; Lin, Hong

    2013-01-01

    Citrus huanglongbing (HLB) is a highly destructive disease of citrus presumably caused by 'Candidatus Liberibacterasiaticus' (Las), a gram-negative, insect-transmitted, phloem-limited α-proteobacterium. Although almost all citrus plants are susceptible to HLB, reports have shown reduced susceptibility to Las infection in lemon (Citrus limon) plants. The aim of this study is to identify intra-species specific molecular mechanisms associated with Las-induced responses in lemon plants. To achieve this, comparative 2-DE and mass spectrometry, in addition to Inductively Coupled Plasma Spectroscopy (ICPS) analyses, were applied to investigate differences in protein accumulation and the concentrations of cationic elements in leaves of healthy and Las-infected lemon plants. Results showed a differential accumulation of 27 proteins, including an increase in accumulation of starch synthase but decrease in the production of photosynthesis-related proteins in Las-infected lemon plants compared to healthy plants. Furthermore, there was a 6% increase (P > 0.05) in K concentration in leaves of lemon plants upon Las infection, which support results from previous studies and might represent a common response pattern of citrus plants to Las infection. Interestingly, contrary to reports from prior studies, this study showed a general reduction in the production of defense-related pathogen-response proteins but a 128% increase in Zn concentration in lemon plants in response to Las infection. Taken together, this study sheds light on general and intra-species specific responses associated with the response of citrus plants to Las.

  9. Hourly predictive artificial neural network and multivariate regression tree models of Alternaria and Cladosporium spore concentrations in Szczecin (Poland)

    Science.gov (United States)

    Grinn-Gofroń, Agnieszka; Strzelczak, Agnieszka

    2009-11-01

    A study was made of the link between time of day, weather variables and the hourly content of certain fungal spores in the atmosphere of the city of Szczecin, Poland, in 2004-2007. Sampling was carried out with a Lanzoni 7-day-recording spore trap. The spores analysed belonged to the taxa Alternaria and Cladosporium. These spores were selected both for their allergenic capacity and for their high level presence in the atmosphere, particularly during summer. Spearman correlation coefficients between spore concentrations, meteorological parameters and time of day showed different indices depending on the taxon being analysed. Relative humidity (RH), air temperature, air pressure and clouds most strongly and significantly influenced the concentration of Alternaria spores. Cladosporium spores correlated less strongly and significantly than Alternaria. Multivariate regression tree analysis revealed that, at air pressures lower than 1,011 hPa the concentration of Alternaria spores was low. Under higher air pressure spore concentrations were higher, particularly when RH was lower than 36.5%. In the case of Cladosporium, under higher air pressure (>1,008 hPa), the spores analysed were more abundant, particularly after 0330 hours. In artificial neural networks, RH, air pressure and air temperature were the most important variables in the model for Alternaria spore concentration. For Cladosporium, clouds, time of day, air pressure, wind speed and dew point temperature were highly significant factors influencing spore concentration. The maximum abundance of Cladosporium spores in air fell between 1200 and 1700 hours.

  10. Fresh-keeping and Antibacterial Technology of Citrus Fruits Based on Ethanol Extracts from Chinese Herbs%基于中药乙醇提取物的柑橘采后保鲜与抑菌技术

    Institute of Scientific and Technical Information of China (English)

    任艳芳; 刘畅; 何俊瑜; 王思梦; 张兰兰

    2012-01-01

    The plant resources with inhibitory effect on postharvest pathogenic fungi from citrus fruits were screened so as to provide the theoretical basis for the development of botanical fungicide. The experiments investigated inhibitory effects in vitro with 30 kinds of ethanol extracts from Chinese herbs against P. italicum, P. digit alum and Alternaria, citri by using mycelial growth rate method, and control effects in vivo and storage effects of Valencia orange with Coptis chinensis ethanol extracts. The results showed that 30 kinds of Chinese herbs ethanol extracts have different effects on mycelial growth of three citrus pathogens, and Coptis chinensis ethanol extracts exhibited the best antifungal effect which reached up to 100%. However, no difference was found between Prochloraz treatment and Coptis chinensis treatment (P> 0.05). Minimum inhibitory concentration (MIC) of Coptis chinensis ethanol extracts is 0. 025 g/mLu Control test showed that the control effect of Coptis chinensis ethanol extracts against the mixtures of three kinds of spores achieved 90. 87% after 10 d of treatment, and there was no significant difference ( P > 0. 05 ) between Coptis chinensis treatment and Prochloraz treatment. Preservation test indicated that Coptis chinensis ethanol extracts could obviously decrease the incidence of rotting rate and molding of Valencia orange fruits, increase the good fruit rate, and retard the losses of titratable acidity and vitamin C in fruits. Compared with Prochloraz treatment, there was no difference (P >0. 05). These results indicated that in vitro experiments, control effect and preservation test exhibited a good antifungal effect with Coptis chinensis ethanol extracts. Therefore, Coptis chinensis ethanol extracts may have a possibility to replace chemical fungicides and a new pesticide can be developed.%以意大利青霉、指状青霉、柑橘链格孢为供试菌种,采用生长速率法对30种中药的乙醇提取物进行离体抑菌试验,

  11. Comparative genomic analysis of Xanthomonas axonopodis pv. citrumelo F1, which causes citrus bacterial spot disease, and related strains provides insights into virulence and host specificity.

    Science.gov (United States)

    Jalan, Neha; Aritua, Valente; Kumar, Dibyendu; Yu, Fahong; Jones, Jeffrey B; Graham, James H; Setubal, João C; Wang, Nian

    2011-11-01

    Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.

  12. Comparative Genomic Analysis of Xanthomonas axonopodis pv. citrumelo F1, Which Causes Citrus Bacterial Spot Disease, and Related Strains Provides Insights into Virulence and Host Specificity ▿ #

    Science.gov (United States)

    Jalan, Neha; Aritua, Valente; Kumar, Dibyendu; Yu, Fahong; Jones, Jeffrey B.; Graham, James H.; Setubal, João C.; Wang, Nian

    2011-01-01

    Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity. PMID:21908674

  13. Conidia of Alternaria, allergy risk factor in Castilla-La Mancha Conidios de 'alternaria', factor de riesgo de alegria en Castilla-La Mancha

    Directory of Open Access Journals (Sweden)

    Silvia Sabariego Ruiz

    2007-12-01

    Full Text Available In this work study the seasonal behaviour of the conidia of Alternaria, as well as the main locations in the Castilla-La Mancha region where the levels of these conidia in the air may pose a risk of allergy for people who are sensitised to them. The study was conducted in 5 sampling stations belonging to the Castilla-La Mancha Aerobiological Network (Red Aerocam: Albacete, Ciudad Real, Cuenca, Guadalajara and Toledo, in 2008. The pollen traps and the sampling methodology used follow the guidelines of the Spanish Aerobiology Network (REA. Alternaria conidia are detected in the atmosphere of Castilla-La Mancha all year round, although the highest concentrations are obtained in May, June and July. The greatest annual concentrations are detected in the cities of Ciudad Real, Toledo y Guadalajara with 5.624 conidia, 4.527 conidia and 4.173 conidia respectively, followed by Albacete and Cuenca. Some locations sampled showed high maximum daily values on a considerable number of days: examples include the levels recorded in Ciudad Real on 20 March (722 conidia/m3, Toledo on 18 June (324 conidia/m3, and Guadalajara on 26 June (220 conidia/m3.En este trabajo se estudia el comportamiento estacional de los conidios de Alternaria en la atmósfera de Castilla-La Mancha, cuyo inte- rés se basa en que los niveles en el aire de estos conidios suponen un riesgo de alergia para las personas sensibilizadas a los mismos. El estudio se ha llevado a cabo en cinco estaciones de muestreo pertenecientes a la Red de Aerobiología de Castilla-La Mancha (Red Aerocam: Albacete, Ciudad Real, Cuenca, Guadalajara y Toledo, durante el año 2008. Los captadores utilizados y la metodología de muestreo siguen las directrices de la Red Española de Aerobiología (REA. Los conidios de Alternaria se detectan en la atmósfera de Castilla-La Mancha durante todo el año, aunque los meses de mayores concentraciones se obtienen en mayo, junio y julio. Ciudad Real, Toledo y Guadalajara

  14. A Research on Control ofAlternaria Panax Whetz by Different Chinese Herbal Medicines%不同中药材对三七黑斑病病原Alternaria panax Whetz抑制作用研究

    Institute of Scientific and Technical Information of China (English)

    陈昱君; 王勇; 刘云芝; 杨建忠; 朱云飞

    2012-01-01

    The paper studies the control ofAlternaria Panax ginseng (Alternaria Panax whetz) byusingdifferent Chinese herbal medicines through antibacterial experiment and field resistance identification, screens out Chinese herbal medicines that can be mixed plant with Panax notoginseng such as Herba Lycopi, Kaempferia galanga L, Radix Ophiopogonis, Rhizoma Polygonati Odorati the results could provide the scientific basis for biodiversity control ofPanax notoginseng black spot disease.%通过不同中药材对黑斑病病原Alternaria panax Whetz.室内抑菌试验研究及病原田间致病性鉴定,筛选出可与三七混种的中药材品种泽兰、山萘、麦冬、玉竹。

  15. Atividades amilolítica e pectinolítica de Alternaria solani e a relação com a agressividade em tomateiro Amilolytic and pectinolytic activities of Alternaria solani and aggressiveness in tomato plants

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Marchi

    2006-09-01

    Full Text Available As atividades amilolítica e pectinolítica de 45 isolados de Alternaria solani, provenientes de diferentes hospedeiros, foram estimadas por meio da difusão enzimática em meio sólido específico e mensuração do halo de degradação do substrato. Todos os isolados degradaram pectina. Apenas 17 isolados apresentaram atividade amilolítica, sendo nove isolados provenientes de batateira. Somente o isolado AS18 se destacou como bom produtor de ambas as enzimas. Uma vez que a atividade pectinolítica foi mais evidente, avaliou-se a influência de pectinases na agressividade de A. solani ao tomateiro. Para isso, cinco isolados (2 de berinjela, 2 de tomateiro e 1 de batateira contrastantes quanto à produção de pectinases foram selecionados para testes em folíolos destacados e plantas inteiras. Quatro isolados foram utilizados no teste em folíolos destacados (AS6, AS7, AS12 e AS26, e constatou-se haver variabilidade patogênica. A correlação obtida entre o tamanho das lesões e a atividade pectinolítica foi de r = 0,963 (P = 0,087. Cinco isolados (AS6, AS7, AS12, AS25 e AS26 foram inoculados em plantas inteiras de tomate. Os isolados não diferiram quanto ao número de lesões/cm² de área foliar, porém variaram em agressividade. Houve correlação (r = 0,916; P = 0,042 entre a atividade de pectinases e o índice de doença, sugerindo possível papel para as enzimas pécticas durante a infecção de A. solani em tomateiro. É provável que as diferenças no perfil enzimático dos isolados estejam associadas ao hospedeiro original de onde os mesmos foram obtidos. Os resultados reforçaram evidências de especificidade por hospedeiro em populações de A. solani.Amilolytic and pectinolytic activities of 45 isolates of Alternaria solani from distinct hosts were investigated. Enzyme secretion was evaluated in glucose-free medium amended with pectin or starch as carbon source. All isolates degraded pectin. Only 17 isolates had amilolytic

  16. Localization and distribution of ‘Candidatus Liberibacter asiaticus’ in citrus and periwinkle by direct tissue blot immuno assay with an anti-OmpA polyclonal antibody

    Science.gov (United States)

    ‘Candidatus Liberibacter asiaticus’ (CaLas), a non-cultured member of the a-proteobacteria, is the causal agent of citrus Huanglongbing (HLB). Due to the difficulties of in vitro culture, antibodies against CaLas have not been widely used in studies of this pathogen. We have used an anti-OmpA poly...

  17. Complete genome sequence of a copper-resistant bacterium from the citrus phyllosphere, #Stenotrophomonas# sp. strain LM091, obtained using long-read technology

    OpenAIRE

    Richard, Damien; Boyer, Claudine; Lefeuvre, Pierre; Pruvost, Olivier

    2016-01-01

    The Stenotrophomonas genus shows great adaptive potential including resistance to multiple antimicrobials, opportunistic pathogenicity, and production of numerous secondary metabolites. Using long-read technology, we report the sequence of a plant-associated Stenotrophomonas strain originating from the citrus phyllosphere that displays a copper resistance phenotype.(Résumé d'auteur)

  18. Complete Genome Sequence of a Copper-Resistant Bacterium from the Citrus Phyllosphere, Stenotrophomonas sp. Strain LM091, Obtained Using Long-Read Technology

    Science.gov (United States)

    Richard, Damien; Boyer, Claudine; Lefeuvre, Pierre

    2016-01-01

    The Stenotrophomonas genus shows great adaptive potential including resistance to multiple antimicrobials, opportunistic pathogenicity, and production of numerous secondary metabolites. Using long-read technology, we report the sequence of a plant-associated Stenotrophomonas strain originating from the citrus phyllosphere that displays a copper resistance phenotype. PMID:27979933

  19. Enhanced resistance to Phytophthora infestans and Alternaria solani in leaves and tubers, respectively, of potato plants with decreased activity of the plastidic ATP/ADP transporter.

    Science.gov (United States)

    Conrath, Uwe; Linke, Christoph; Jeblick, Wolfgang; Geigenberger, Peter; Quick, W Paul; Neuhaus, H Ekkehard

    2003-05-01

    Recently, it has been reported that tubers of transgenic potato ( Solanum tuberosum L.) plants with decreased activity of the plastidic ATP/ADP transporter (AATP1) contain less starch, despite having an increased glucose level [P. Geigenberger et al. (2001) Plant Physiol 125:1667-1678]. The metabolic alterations correlated with enhanced resistance to the bacterium Erwinia carotovora. Here it is shown that transgenic potato tubers, possessing less starch yet increased glucose levels due to the expression of a cytoplasm-localized yeast invertase, exhibit drastic susceptibility to E. carotovora. In addition, it is demonstrated that AATP1 anti-sense tubers show an increased capacity to ward off the pathogenic fungus Alternaria solani. In contrast to AATP1 anti-sense tubers, the corresponding leaf tissue does not show changes in carbohydrate accumulation. However, upon elicitor treatment, AATP1 anti-sense leaves possess an increased capacity to release H(2)O(2) and activate various defence-related genes, reactions that are associated with substantially delayed appearance of disease symptoms caused by Phytophthora infestans. Grafting experiments between AATP1 anti-sense plants and wild-type plants indicate the presence of a signal that is generated in AATP1 rootstocks and primes wild-type scions for potentiated activation of cellular defence responses in leaves. Together, the results suggest that (i) the enhanced pathogen tolerance of AATP1 anti-sense tubers is not due to "high sugar resistance", (ii) the increased disease resistance of AATP1 anti-sense tubers is effective against different types of pathogen and (iii) a systemic signal induced by antisensing the plastidic ATP/ADP transporter in potato tubers confers increased resistance to pathogens.

  20. IDENTIFICATION AND QUANTIFICATION OF DIFFERENTIALLY EXPRESSED GENES ASSOCIATED WITH CITRUS BLIGHT (Citrus spp.

    Directory of Open Access Journals (Sweden)

    José Renato de Abreu

    2015-02-01

    Full Text Available Brazil is the largest citrus producer in the world, being responsible for more than 20% of its production, which is, however still low due to phytosanitary issues such as citrus blight. Citrus blight is an anomaly whose causes still have not yet been determined, therefore there are no efficient control measures to minimize the production losses with the use of resistant varieties being considered the most appropriate method. However, little is known about the genes involved in the defense response of the plants to this anomaly. Considering that many physiological alterations associated with plant stress responses are controlled at a transcriptional level, in this study we sought the identification and characterization of the gene expression products differentially expressed in the response to the citrus blight. Through the suppressive subtractive hybridization technique, expressed cDNA libraries were built using mRNAs isolated from "Cravo" lemon tree roots (Citrus limonia L. Osbeck under "Pera" orange (Citrus sinensis L. Osbeck of healthy and sick plants. 129 clones were obtained by subtraction and their sequences were compared in databases. 34 of them linked to proteins associated to stress processes, while the others were similar to sequences of unknown functions or did not present similarity with sequences deposited in the databases. 3 genes were selected and their expressions were studied by RT - qPCR in real-time. Plants with citrus blight presented an increase of the expression level in two of those genes, suggesting that these can be directly involved with this anomaly.

  1. Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii.

    Science.gov (United States)

    Moreira, Leandro M; Almeida, Nalvo F; Potnis, Neha; Digiampietri, Luciano A; Adi, Said S; Bortolossi, Julio C; da Silva, Ana C; da Silva, Aline M; de Moraes, Fabrício E; de Oliveira, Julio C; de Souza, Robson F; Facincani, Agda P; Ferraz, André L; Ferro, Maria I; Furlan, Luiz R; Gimenez, Daniele F; Jones, Jeffrey B; Kitajima, Elliot W; Laia, Marcelo L; Leite, Rui P; Nishiyama, Milton Y; Rodrigues Neto, Julio; Nociti, Letícia A; Norman, David J; Ostroski, Eric H; Pereira, Haroldo A; Staskawicz, Brian J; Tezza, Renata I; Ferro, Jesus A; Vinatzer, Boris A; Setubal, João C

    2010-04-13

    Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.

  2. Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii

    Directory of Open Access Journals (Sweden)

    Nociti Letícia A

    2010-04-01

    Full Text Available Abstract Background Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. Results We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. Conclusion We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.

  3. Titers of 'Ca. Liberibacter asiaticus' in Murraya paniculata and Murraya-reared Diaphorina citri Are Much Lower than in Citrus and Citrus-reared Psyllids

    National Research Council Canada - National Science Library

    Walter, Abigail; Duan, Y; Hall, David G

    2012-01-01

    Huanglongbing, one of the most devastating diseases of citrus, is associated with the bacterium 'Candidatus Liberibacter asiaticus' vectored by the Asian citrus psyllid, Diaphorina citri, in North America...

  4. Detection of citrus canker and Huanglongbing using fluorescence imaging spectroscopy and support vector machine technique.

    Science.gov (United States)

    Wetterich, Caio Bruno; Felipe de Oliveira Neves, Ruan; Belasque, José; Marcassa, Luis Gustavo

    2016-01-10

    Citrus canker and Huanglongbing (HLB) are citrus diseases that represent a serious threat to the citrus production worldwide and may cause large economic losses. In this work, we combined fluorescence imaging spectroscopy (FIS) and a machine learning technique to discriminate between these diseases and other ordinary citrus conditions that may be present at citrus orchards, such as citrus scab and zinc deficiency. Our classification results are highly accurate when discriminating citrus canker from citrus scab (97.8%), and HLB from zinc deficiency (95%). These results show that it is possible to accurately identify citrus diseases that present similar symptoms.

  5. CONTROL OF Alternaria porri (E11 CIF. AND TOXIC EFFECT OF CAPTAFOL SPRAYING IN GARLIC (Allium sativum L. CONTROLE DE Alternaria porri (E11 Cif. E EFEITO FITOTÓXICO DE CAPTAFOL EM PULVERIZAÇÃO NA CULTURA DO ALHO (Allium sativum L.

    Directory of Open Access Journals (Sweden)

    Iraídes Fernandes Carneiro

    2007-09-01

    Full Text Available

    The objective of the present work was to verify the effect of the different concentrations of the captafol fungicide (0, 50, 100, 200 and 400 g.i.a./100 l of water, in the control of Alternaria porri (E11 Cif. and their toxic effects on plants, in two cultivars of garlic (Lavinia and Centenário. The results show that, for the cultivars tested, the fungicide, in the concentrations utilized, didn’t control the pathogen, and it didn’t show fitotoxicity.

    Com o objetivo de verificar o efeito do Captafol no controle de Alternaria porri (E11 Cif. na cultura do alho, e seus efeitos fitotóxicos nesta A1iácea, foi instalado um experimento nas dependências da Escola de Agronomia da Universidade Federal de Goiás, em Goiânia. O delineamento experimental foi de blocos ao acaso com parcelas subdivididas utilizando-se as cultivares Lavinia e Centenário, submetidas a pulverizações com o fungicida nas seguintes concentrações: 0, 50, 100, 200 e 400 gramas do princípio ativo por 100 litros de água. Os resultados indicam que, para as duas cultivares utilizadas, o Captafol não controlou o patógeno, nem se mostrou fitotóxico.

  6. Natural occurrence of mycotoxins and toxigenic capacity of Alternaria strains from mouldy peppers

    DEFF Research Database (Denmark)

    da Cruz Cabral, Lucía; Terminiello, Laura; Fernández Pinto, Virginia

    2016-01-01

    Sweet pepper (Capsicum annuum) is an important crop cultivated worldwide, with Argentina being one of the major producers in South America. The fruit is susceptible to several fungal diseases, leading to severe economic losses for producers. In this study, Alternaria was found as the prevalent...... and alternariols. A total 32 out of 48 spoiled pepper fruits were contaminated with at least one of these metabolites. Half of the samples were positive for tenuazonic acid (range 8–11,422 μg/kg), while alternariol and its monomethyl ether were less frequently detected (21 and 29%, respectively) and at lower...

  7. Solanapyrones, Phytotoxins Produced by Alternaria solani: Biosynthesis and Isolation of Minor Components.

    Science.gov (United States)

    Oikawa, H; Yokota, T; Sakano, C; Suzuki, Y; Naya, A; Ichihara, A

    1998-01-01

    Two minor components of solanapyrones D and E, phytotoxins from Alternaria solani, were isolated. The absolute stereochemistry of D and the optical purity of solanapyrones A and D were determined by chemical transformation and measurement of the CD spectrum. In addition, complete signal assignment of the (1)H- and (13)C-NMR spectra of solanapyrones A and D, and their solution conformations were studied. Feeding experiments with various isotopically labeled acetates and methionine established the biosynthetic pathway of solanapyrones. The phytotoxicity of solanapyrones on lettuce seedlings is discussed.

  8. Chemical composition and fungicidal activity of the essential oil of Thymus vulgaris against Alternaria citri

    Directory of Open Access Journals (Sweden)

    Erica A. Soto Mendívil

    2006-01-01

    Full Text Available Se analizó químicamente el aceite esencial de tomillo (Thymus vulgaris L. por Cromatografía de Gases/Espectroscopia de Masas y se evaluó su actividad fungicida. Los principales constituyentes fueron borneol (28.4%, timol (16.6%, carvacrol metil eter (9.6%, camfeno (6.9%, α-humulene (6.4% y carvacrol (5.0%. Las pruebas de actividad fungicida (in vitro indicaron que la concentración de 1000ppm del aceite esencial de tomillo fue efectivo para inhibir a Alternaria citri, cuando se adicionó al medio de cultivo agar papa dextrosa

  9. ENZYMATIC KINETIC STUDY HYDROLASE FROM CITRUS

    Directory of Open Access Journals (Sweden)

    Israel Hernández

    2015-09-01

    Full Text Available In this paper the degrading activity of enzymes derived from orange peels (Citrus x sinensis, grapefruit (Citrus paradise and pineapple (Ananas comosus on the organic matter in wastewater is evaluated. This activity is measured indirectly by quantifying the biochemical oxygen demand (COD before and after degradation process based on a period of time using the HACH DR / 2010, and then the kinetic study was performed by the differential method and integral with the experimental data, obtaining a reaction order of 1 to pectinase (orange, and order 2 for bromelain (pineapple.

  10. Development of SSR markers from Citrus clementina (Rutaceae) BAC end sequences and interspecific transferability in Citrus.

    Science.gov (United States)

    Ollitrault, Frédérique; Terol, Javier; Pina, Jose Antonio; Navarro, Luis; Talon, Manuel; Ollitrault, Patrick

    2010-11-01

    Microsatellite primers were developed from bacterial artificial chromosome (BAC) end sequences of Citrus clementina and their transferability and polymorphism tested in the genus Citrus for future anchorage of physical and genetic maps and comparative interspecific genetic mapping. • Using PAGE and DNA silver staining, 79 primer pairs were selected for their transferability and polymorphism among 526 microsatellites mined in BES. A preliminary diversity study in Citrus was conducted with 18 of them, in C. reticulata, C. maxima, C. medica, C. sinensis, C. aurantium, C. paradisi, C. lemon, C. aurantifolia, and some papedas (wild citrus), using a capillary electrophoresis fragment analyzer. Intra- and interspecific polymorphism was observed, and heterozygous markers were identified for the different genotypes to be used for genetic mapping. • These results indicate the utility of the developed primers for comparative mapping studies and the integration of physical and genetic maps.

  11. New cytotoxic compounds of endophytic fungus Alternaria sp. isolated from Broussonetia papyrifera (L.) Vent.

    Science.gov (United States)

    Zhang, Naidan; Zhang, Chunyan; Xiao, Xiao; Zhang, Qiaoyan; Huang, Baokang

    2016-04-01

    From the ethyl acetate extract of a culture of the endophytic fungus Alternaria species G7 in Broussonetia papyrifera, a new compound altertoxin IV (1) together with nine known compounds were isolated and identified by means of bioassay-guided fractionation. The structures of these compounds were established on the basis of spectroscopic methods, among which the absolute configuration of compound 1, a new tetrahydroperylenone derivative, was determined by means of X-Ray Crystallographic analysis. The isolated compounds were subjected to cytotoxic activity against three human cancer cell lines (A549, MG-63, and SMMC-7721). Compound 2 showed significant cytotoxic activities against tested cell lines, with IC50 values of 1.47, 2.11 and 7.34 μg/mL, respectively. Additionally, compound 4 also exhibited significant cytotoxic activities against cell lines MG-63 and SMMC-7721, with IC50 values of 0.53 and 2.92 μg/mL. Endophytic fungi Alternaria from B. papyrifera might be promising sources of natural bioactive and novel metabolites.

  12. Altering Conidial Dispersal of Alternaria solani by Modifying Microclimate in Tomato Crop Canopy

    Directory of Open Access Journals (Sweden)

    Prashant Prakash Jambhulkar

    2016-12-01

    Full Text Available Early blight of tomato caused by Alternaria solani, is responsible for severe yield losses in tomato. The conidia survive on soil surface and old dry lower leaves of the plant and spread when suitable climatic conditions are available. Macroclimatic study reveals that highest inoculum concentration of Alternaria spores appeared in May 2012 to 2013 and lowest concentration during January 2012 to 2013. High night temperature positively correlated and significantly (P < 0.01 involved in conidial spore dispersal and low relative humidity (RH displayed significant (P < 0.05 but negative correlation with conidial dispersal. The objective of the study was to modify microclimatic conditions of tomato crop canopy which may hamper conidial dispersal and reduce disease severity. We evaluated effect of marigold intercropping and plastic mulching singly and in consortia on A. solani conidial density, tomato leaf damage and microclimatic parameters as compar to tomato alone (T. Tomato-marigold intercropping–plastic mulching treatment (T + M + P showed 35–39% reduction in disease intensity as compared to tomato alone. When intercropped with tomato, marigold served as barrier to conidial movement and plastic mulching prevented evapotranspiration and reduced the canopy RH that resulted in less germination of A. solani spores. Marigold intercropping and plastic mulching served successfully as physical barrier against conidial dissemination to diminish significantly the tomato foliar damage produced by A. solani.

  13. COLONIZATION OF GRAPE BERRIES BY REPRESENTATIVES OF THE GENUS ALTERNARIA AND THEIR OCCURRENCE IN THE STUM

    Directory of Open Access Journals (Sweden)

    Zuzana Mašková

    2013-02-01

    Full Text Available The aim of the study was to analyze the mycobiota occurring on the grapes originating from Slovak wine-growing regions. The main focus was to discover the presence of the representatives of the genus Alternaria on/in grape berries and in the stum.Using the direct method of placing grape berries on the culture medium was analyzed their total and endogenous (after superficial sterilization mycobiota. Plate dilution method was used for stum mycobiota determination. Alternaria spp. colonized grapeson the surface and inside with anisolation frequency (Fr of 100%. Moreover, 100% of the stum samples were positive for the presence of this genus. Their relative density (RD was 44.9% (unsterilized grapes, 57.9% (sterilized grapes and 6.35% (stum. In all the areas analysed we recorded 4 species-groups: A. alternata, A. arborescens, A. infectoria and A. tenuissima. With the highest Fr and RD occurredA. tenuissima species-group, followed by A. alternata and A. arborescens species-groups. All of them are potential producers of mycotoxins as alternariol, alternariol monomethylether, tenuazonic acid, altertoxin I, II and III.

  14. Effectiveness of Phenolic Compounds against Citrus Green Mould

    Directory of Open Access Journals (Sweden)

    Simona M. Sanzani

    2014-08-01

    Full Text Available Stored citrus fruit suffer huge losses because of the development of green mould caused by Penicillium digitatum. Usually synthetic fungicides are employed to control this disease, but their use is facing some obstacles, such public concern about possible adverse effects on human and environmental health and the development of resistant pathogen populations. In the present study quercetin, scopoletin and scoparone—phenolic compounds present in several agricultural commodities and associated with response to stresses—were firstly tested in vitro against P. digitatum and then applied in vivo on oranges cv. Navelina. Fruits were wound-treated (100 µg, pathogen-inoculated, stored and surveyed for disease incidence and severity. Although only a minor (≤13% control effect on P. digitatum growth was recorded in vitro, the in vivo trial results were encouraging. In fact, on phenolic-treated oranges, symptoms appeared at 6 days post-inoculation (DPI, i.e., with a 2 day-delay as compared to the untreated control. Moreover, at 8 DPI, quercetin, scopoletin, and scoparone significantly reduced disease incidence and severity by 69%–40% and 85%–70%, respectively, as compared to the control. At 14 DPI, scoparone was the most active molecule. Based on the results, these compounds might represent an interesting alternative to synthetic fungicides.

  15. Yield and quality responses of citrus (Citrus reticulate) and tea (Podocarpus fleuryi Hickel.) to compound fertilizers

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; SHI Xue-gen; WEI You-zhang; YANG Xiao-e; UOTI Juhani

    2006-01-01

    Experiments were carried out with citrus (Citrus reticulate) and tea (Podocarpus fleuryi Hickel.) to studythe effects of compound fertilizers on their yieldsand quality. In the citrus experiment, application of compound fertilizers increased available P,K and Mg contents in soil but decreased alkali-hydrolyzable N contents in soil and N, P and K contents in leaves. In the tea experiment, application of compound fertilizers increased available P, K and Mg contents in soil and N, P, K and Mg contents in leaves but decreased alkali-hydrolyzable N in soil compared with the urea treatment. Application of compound fertilizers could improve the quality of citrus and tea, increase their yields and enhance their economical profits significantly. Compared with the control, application of compound fertilizers increased citrus yields by 6.31, 12.94 and 17.69 t/ha, and those of tea by 0.51, 0.86 and 1.30 t/ha, respectively. Correspondingly, profits were increased by 21.4% to 61.1% for citrus and by 10.0% to 15.7% for tea.Optimal rates of compound fertilizers were recommended for both crops.

  16. Citrus leprosis virus N: A New Dichorhavirus Causing Citrus Leprosis Disease.

    Science.gov (United States)

    Ramos-González, Pedro Luis; Chabi-Jesus, Camila; Guerra-Peraza, Orlene; Tassi, Aline Daniele; Kitajima, Elliot Watanabe; Harakava, Ricardo; Salaroli, Renato Barbosa; Freitas-Astúa, Juliana

    2017-08-01

    Citrus leprosis (CL) is a viral disease endemic to the Western Hemisphere that produces local necrotic and chlorotic lesions on leaves, branches, and fruit and causes serious yield reduction in citrus orchards. Samples of sweet orange (Citrus × sinensis) trees showing CL symptoms were collected during a survey in noncommercial citrus areas in the southeast region of Brazil in 2013 to 2016. Transmission electron microscopy analyses of foliar lesions confirmed the presence of rod-like viral particles commonly associated with CL in the nucleus and cytoplasm of infected cells. However, every attempt to identify these particles by reverse-transcription polymerase chain reaction tests failed, even though all described primers for the detection of known CL-causing cileviruses and dichorhaviruses were used. Next-generation sequencing of total RNA extracts from three symptomatic samples revealed the genome of distinct, although highly related (>92% nucleotide sequence identity), viruses whose genetic organization is similar to that of dichorhaviruses. The genome sequence of these viruses showed citrus trees and those used for the transmission of one of the characterized isolates to Arabidopsis plants were anatomically recognized as Brevipalpus phoenicis sensu stricto. Molecular and biological features indicate that the identified viruses belong to a new species of CL-associated dichorhavirus, which we propose to call Citrus leprosis N dichorhavirus. Our results, while emphasizing the increasing diversity of viruses causing CL disease, lead to a reevaluation of the nomenclature of those viruses assigned to the genus Dichorhavirus. In this regard, a comprehensive discussion is presented.

  17. Computational identification of citrus microRNAs and target analysis in citrus expressed sequence tags.

    Science.gov (United States)

    Song, C; Jia, Q; Fang, J; Li, F; Wang, C; Zhang, Z

    2010-11-01

    MicroRNAs (miRNAs) are a new family of small RNA molecules found in plants and animals. We developed a comprehensive strategy for identifying new miRNA homologues by mining the repository of available citrus expressed sequence tags (ESTs). By adopting a range of filtering criteria, we identified a total of 38 potential miRNAs--nine, five, nine and 15 miRNAs in Citrus trifoliata (ctr-miRNAs), C. clementina (ccl-miRNAs), C. reticulata (crt-miRNAs) and C. sinensis (csi-miRNAs), respectively--from more than 430,000 EST sequences in citrus. Using the potential miRNA sequences, we conducted a further BLAST search of the mRNA database and found six potential target genes in these citrus species. Eight miRNAs were selected in order to verify their existence in citrus using Northern blotting, and the functions of several miRNAs in miRNA-mediated gene regulation are experimentally suggested. It appears that all these miRNAs regulate expression of their target genes by cleavage, which is the most common situation in gene regulation mediated by plant miRNAs. Our achievement in identifying new miRNAs in citrus provides a powerful incentive for further studies on the important roles of these miRNAs.

  18. The Citrus Sanitation Center of Estación Experimental Agroindustrial Obispo Colombres, Tucumán, Argentina El Centro de Saneamiento de Citrus de la Estación Experimental Agroindustrial Obispo Colombres de Tucumán, Argentina

    Directory of Open Access Journals (Sweden)

    Beatriz E. Stein

    Full Text Available In October 2004, the Estación Experimental Agroindustrial Obispo Colombres (Tucumán, Argentina founded its Citrus Sanitation Center. The goal of this center is to establish and keep a group of the most important citrus varieties and rootstocks true to type and free of graft-transmissible pathogens. These will be used as primary sources of propagating material for citrus growers and researchers in northwestern Argentina. Mother trees of the main commercial citrus varieties were selected from the germplasm bank of the experiment station and were recovered through the standard procedure of shoot tip grafting (STG. Healthy plants are carefully and periodically indexed by biological, serological and molecular methods for tristeza, psorosis, exocortis, cachexia, citrus variegated chlorosis, citrus canker and huanglongbing. The Citrus Sanitation Center will maintain a supply of healthy propagation material and will continue a program initiated in 1966, consting in introducing, producing and releasing nucellar clones.La Estación Experimental Agroindustrial Obispo Colombres (EEAOC creó en el año 2004 el Centro de Saneamiento de Citrus (CSC para la ejecución de tareas de limpieza y diagnóstico de virus en cítricos. El objetivo de este centro es establecer y mantener un plantel de plantas madres cítricas, de variedades copa y portainjertos, de alta calidad genética y libre de plagas y enfermedades transmisibles por injerto. Este grupo de plantas se constituye como fuente primaria de material de propagación para productores, viveristas e investigadores del noroeste argentino. Las plantas madres de las principales variedades comerciales de cítricos se seleccionaron del banco de germoplasma de la EEAOC y se recuperaron por la técnica de microinjerto de ápices caulinares, procedimiento estándar utilizado en la limpieza de plantas cítricas. Periódicamente se verifica su sanidad por métodos biológicos, serológicos y moleculares para las

  19. Ulvans induce resistance against plant pathogenic fungi independently of their sulfation degree.

    Science.gov (United States)

    de Freitas, Mateus B; Ferreira, Luciana G; Hawerroth, Caroline; Duarte, Maria Eugênia R; Noseda, Miguel D; Stadnik, Marciel J

    2015-11-20

    The present work aimed to evaluate the defense responses induced by chemically sulfated ulvans in Arabidopsis thaliana plants against the phytopathogenic fungi Alternaria brassicicola and Colletotrichum higginsianum. Derivatives with growing sulfate content (from 20.9 to 36.6%) were prepared with SO3-pyridine complex in formamide. NMR and FTIR spectroscopic analyses confirmed the increase of sulfate groups after the chemical sulfation process. The native sulfated polysaccharide (18.9% of sulfate) and its chemically sulfated derivatives similarly reduced the severity of both pathogenic fungi infections. Collectively, our results suggest that ulvans induce resistance against both fungal pathogens independently of its sulfation degree.

  20. Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants

    NARCIS (Netherlands)

    Araujo, W.L.; Marcon, J.; jr. Maccheroni, W.; Elsas, van J.D.; Vuurde, van J.W.L.; Azevedo, de J.L.

    2002-01-01

    Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as

  1. Collection and chemical composition of phloem sap from Citrus sinensis L. Osbeck (sweet orange).

    Science.gov (United States)

    Hijaz, Faraj; Killiny, Nabil

    2014-01-01

    Through utilizing the nutrient-rich phloem sap, sap feeding insects such as psyllids, leafhoppers, and aphids can transmit many phloem-restricted pathogens. On the other hand, multiplication of phloem-limited, uncultivated bacteria such as Candidatus Liberibacter asiaticus (CLas) inside the phloem of citrus indicates that the sap contains all the essential nutrients needed for the pathogen growth. The phloem sap composition of many plants has been studied; however, to our knowledge, there is no available data about citrus phloem sap. In this study, we identified and quantified the chemical components of phloem sap from pineapple sweet orange. Two approaches (EDTA enhanced exudation and centrifugation) were used to collect phloem sap. The collected sap was derivatized with methyl chloroformate (MCF), N-methyl-N- [tert-butyl dimethylsilyl]-trifluroacetamide (MTBSTFA), or trimethylsilyl (TMS) and analyzed with GC-MS revealing 20 amino acids and 8 sugars. Proline, the most abundant amino acid, composed more than 60% of the total amino acids. Tryptophan, tyrosine, leucine, isoleucine, and valine, which are considered essential for phloem sap-sucking insects, were also detected. Sucrose, glucose, fructose, and inositol were the most predominant sugars. In addition, seven organic acids including succinic, fumaric, malic, maleic, threonic, citric, and quinic were detected. All compounds detected in the EDTA-enhanced exudate were also detected in the pure phloem sap using centrifugation. The centrifugation technique allowed estimating the concentration of metabolites. This information expands our knowledge about the nutrition requirement for citrus phloem-limited bacterial pathogen and their vectors, and can help define suitable artificial media to culture them.

  2. Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae).

    Science.gov (United States)

    Kuhns, Emily H; Martini, Xavier; Hoyte, Angel; Stelinski, Lukasz L

    2016-07-14

    The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices.

  3. Complete genome sequence of citrus huanglongbing bacterium, 'Candidatus Liberibacter asiaticus' obtained through metagenomics.

    Science.gov (United States)

    Duan, Yongping; Zhou, Lijuan; Hall, David G; Li, Wenbin; Doddapaneni, Harshavardhan; Lin, Hong; Liu, Li; Vahling, Cheryl M; Gabriel, Dean W; Williams, Kelly P; Dickerman, Allan; Sun, Yijun; Gottwald, Tim

    2009-08-01

    Citrus huanglongbing is the most destructive disease of citrus worldwide. It is spread by citrus psyllids and is associated with a low-titer, phloem-limited infection by any of three uncultured species of alpha-Proteobacteria, 'Candidatus Liberibacter asiaticus', 'Ca. L. americanus', and 'Ca. L. africanus'. A complete circular 'Ca. L. asiaticus' genome has been obtained by metagenomics, using the DNA extracted from a single 'Ca. L. asiaticus'-infected psyllid. The 1.23-Mb genome has an average 36.5% GC content. Annotation revealed a high percentage of genes involved in both cell motility (4.5%) and active transport in general (8.0%), which may contribute to its virulence. 'Ca. L. asiaticus' appears to have a limited ability for aerobic respiration and is likely auxotrophic for at least five amino acids. Consistent with its intracellular nature, 'Ca. L. asiaticus' lacks type III and type IV secretion systems as well as typical free-living or plant-colonizing extracellular degradative enzymes. 'Ca. L. asiaticus' appears to have all type I secretion system genes needed for both multidrug efflux and toxin effector secretion. Multi-protein phylogenetic analysis confirmed 'Ca. L. asiaticus' as an early-branching and highly divergent member of the family Rhizobiaceae. This is the first genome sequence of an uncultured alpha-proteobacteria that is both an intracellular plant pathogen and insect symbiont.

  4. The information extraction of Gannan citrus orchard based on the GF-1 remote sensing image

    Science.gov (United States)

    Wang, S.; Chen, Y. L.

    2017-02-01

    The production of Gannan oranges is the largest in China, which occupied an important part in the world. The extraction of citrus orchard quickly and effectively has important significance for fruit pathogen defense, fruit production and industrial planning. The traditional spectra extraction method of citrus orchard based on pixel has a lower classification accuracy, difficult to avoid the “pepper phenomenon”. In the influence of noise, the phenomenon that different spectrums of objects have the same spectrum is graveness. Taking Xunwu County citrus fruit planting area of Ganzhou as the research object, aiming at the disadvantage of the lower accuracy of the traditional method based on image element classification method, a decision tree classification method based on object-oriented rule set is proposed. Firstly, multi-scale segmentation is performed on the GF-1 remote sensing image data of the study area. Subsequently the sample objects are selected for statistical analysis of spectral features and geometric features. Finally, combined with the concept of decision tree classification, a variety of empirical values of single band threshold, NDVI, band combination and object geometry characteristics are used hierarchically to execute the information extraction of the research area, and multi-scale segmentation and hierarchical decision tree classification is implemented. The classification results are verified with the confusion matrix, and the overall Kappa index is 87.91%.

  5. Transmission and Propagation of 'Candidatus Liberibacter asiaticus' by Grafting with Individual Citrus Leaves.

    Science.gov (United States)

    Hilf, Mark E; Lewis, Reid S

    2016-05-01

    Huanglongbing (HLB) is a chronic, progressive decline disease in citrus associated with a systemic infection by the bacterium 'Candidatus Liberibacter asiaticus'. Transmission of the bacterium in the field is by the Asian citrus psyllid, Diaphorina citri Kuwayama. Experimental propagation of 'Ca. L. asiaticus' is done primarily by grafting pieces of bud wood from an infected plant. To produce a small-scale model system for investigation of pathogen biology, we investigated grafting single leaves from infected citrus plants as sources of inoculum for propagation of the bacterium. In total, 162 plants ranging in age from 3 to 18 months were grafted. Grafting with intact asymptomatic and HLB-symptomatic leaves resulted in 61 of 78 (78%) and 35 of 41 (85%) of the plants infected with 'Ca. L. asiaticus', respectively. Inoculum consisting of the leaf petiole only or only an inoculum tissue remnant under the bark of the receptor tree resulted in 6 of 12 (50%) and 7 of 31 (23%) infected trees, respectively. Real-time polymerase chain reaction (qPCR) assays verified the infection in plants, a majority of which developed the foliar blotchy mottle symptom considered diagnostic for HLB, while some plants also displayed the stunted, chlorotic shoots for which the disease is named. The qPCR data together with the symptoms displayed demonstrated that individual leaves from infected trees can serve as effective inoculum sources for transmission and propagation of 'Ca. L. asiaticus' via grafting.

  6. Control of Citrus Huanglongbing (HLB) via Trunk Injection of Plant Activators and Antibiotics.

    Science.gov (United States)

    Hu, Jiahuai; Jiang, Junxi; Wang, Nian

    2017-09-15

    Citrus Huanglongbing (HLB) or greening is a devastating disease of citrus worldwide and no effective control measure is currently available. Plant activators represent environment friendly compounds capable of inducing resistance against many plant pathogens. Earlier studies showed that foliar spray of plant defense inducers could slow down HLB disease progress. In this study, eight plant activators and three antibiotics were evaluated in 3 field trials for their effect to control HLB by trunk injection of young and mature sweet orange trees. Results showed that 4 trunk injections of several activators including salicylic acid, oxalic acid, acibenzolar-S-methyl and potassium phosphate provided significant control of HLB by suppressing Las titer and disease progress. Trunk injection of penicillin, streptomycin and oxytetracycline hydrochloride resulted in excellent control of HLB. In general, antibiotics were more effective in reduction of Las titer and HLB symptom expressions than plant activators. These treatments also resulted in increased yield and better fruit quality. Injection of both salicylic acid and acibenzolar-S-methyl led to significant induction of PR-1 and PR-2 genes. Meanwhile, injection of either potassium phosphate or oxalic acid resulted in significant induction of PR-2 or PR-15 gene expression, respectively. These results suggested that HLB diseased trees remained inducible for systemic acquired resistance (SAR) under field conditions. In summary, this study presents information regarding controlling HLB via trunk injection of plant defense activators and antibiotics, which helps citrus growers in decision-making regarding developing an effective HLB management program. .

  7. Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae

    Directory of Open Access Journals (Sweden)

    Emily H. Kuhns

    2016-07-01

    Full Text Available The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices.

  8. Variety of plant pathogens of ornamental shrubs of the genus Rosa L.

    Directory of Open Access Journals (Sweden)

    Marchenko Alla Borisovna

    2015-12-01

    In the Ukraine’s forest-steppe environment, over the years of research, the most common disease among different representatives of the genus Rosa L. is Diplocarpon rosae FA Wolf, about 52.7%. Diseases caused by Sphaerotheca pannosa var. rosae Woron account for 28.3%: Coniothyrium wernsdorffiae Laubert―19.2%; Botrytis cinerea Pers.―16.9%; Phragmidium mucronatum (Pers. Schltdl., Phragmidium tuberculatum Müll. Hal., Nectria cinnabarina (Tode Fr.―from 7.2 to 6.7%. Pathogens Alternaria alternata (Fr. Keissl., Alternaria tenuissima (Kunze Wiltshire, Fusarium oxysporum Schltdl., Fusarium solani (Mart. Sacc., Phytophthora cactorum J. Schröt., Verticillium dahliae Kleb., Verticillium albo-atrum Reinke Berthold are less common―5%.

  9. 一种快速、特异性检测小麦中链格孢菌(Alternaria alternata)的巢式 PCR 方法%A Rapid and Specific Nest-PCR Method for Detection of Alternaria alternata in Wheat

    Institute of Scientific and Technical Information of China (English)

    秦召; 李巧云; 段宗彪; 姜玉梅; 牛吉山

    2014-01-01

    为建立检测小麦中链格孢菌(Alternaria alternata )的方法,从河南省小麦黑胚籽粒上分离得到7个优势 A.alternata 病原菌株,对其 rDNA 的内部转录间隔区序列(ITS)进行测序,序列比较表明,分离到的病原菌株与 GenBank 公布的 A.alternata 的 ITS 区序列一致性达到99%~100%。根据 Alternaria 属菌株(A.alternata、A.tenuis、A.tenuissima)和麦类根腐离蠕孢菌(Bipolaris sorokiniana )的 ITS 序列比对结果,设计出1对 A.alternata 特异性引物 Aa1F/Aa1R。利用多种河南省小麦的主要病原真菌对该引物的特异性进行验证,只有在 A.alternata 中能特异性地扩增出1条443 bp 的 DNA 片段。以真菌通用引物 ITS1/ITS4为外侧引物、特异性引物Aa1F/Aa1R 为内侧引物进行巢式 PCR 扩增,能检测到 A.alternata DNA 的最低质量浓度为50 pg/μL。因此,建立的巢式 PCR 方法能够快速、特异地检测小麦中的 A.alternata。%The aim of this study was to establish a method for detection of Alternaria alternata in wheat.Seven dominating isolates of A.alternata from wheat black point grains in Henan province were collected,and then their internal transcribed spacer(ITS)regions in rDNA were sequenced, and the sequence analysis showed that the ITS sequences were highly similar among isolates of A.alternata isolated in this study and in GenBank by 99%-100%.According to the comparative result of ITS sequences of Alternaria spp.(A.alternate,A.tenuis,A.tenuissima)and Bipolaris sorokiniana,a pair of primers,namely Aa1F and Aa1R,were designed.Specificity of the primers was tested with several major fungal pathogens of wheat in Henan province,and a 443 bp specific DNA fragment could be amplified only from A.alternata.A rapid and specific nest-PCR method for detection of A.alternata in wheat was established with fungal universal primers ITS1/ITS4 as the outer primers and Aa1F/Aa1R as the inner primers

  10. Efficacy of Chaetomium Species as Biological Control Agents against Phytophthora nicotianae Root Rot in Citrus.

    Science.gov (United States)

    Hung, Phung Manh; Wattanachai, Pongnak; Kasem, Soytong; Poeaim, Supattra

    2015-09-01

    Thailand is one of the largest citrus producers in Southeast Asia. Pathogenic infection by Phytophthora, however, has become one of major impediments to production. This study identified a pathogenic oomycete isolated from rotted roots of pomelo (Citrus maxima) in Thailand as Phytophthora nicotianae by the internal transcribed spacer ribosomal DNA sequence analysis. Then, we examined the in vitro and in vivo effects of Chaetomium globosum, Chaetomium lucknowense, Chaetomium cupreum and their crude extracts as biological control agents in controlling this P. nicotianae strain. Represent as antagonists in biculture test, the tested Chaetomium species inhibited mycelial growth by 50~56% and parasitized the hyphae, resulting in degradation of P. nicotianae mycelia after 30 days. The crude extracts of these Chaetomium species exhibited antifungal activities against mycelial growth of P. nicotianae, with effective doses of 2.6~101.4 µg/mL. Under greenhouse conditions, application of spores and methanol extracts of these Chaetomium species to pomelo seedlings inoculated with P. nicotianae reduced root rot by 66~71% and increased plant weight by 72~85% compared to that in the control. The method of application of antagonistic spores to control the disease was simple and economical, and it may thus be applicable for large-scale, highly effective biological control of this pathogen.

  11. Rheology and composition of processed citrus fiber

    Science.gov (United States)

    While fibrous byproducts are abundant in supply, using them in food products in such a way to not degrade taste or texture can be challenging. Citrus fibers have been shown to have high water holding and viscous properties. However, to better incorporate dried orange pulp into foods, their propert...

  12. Detection of Citrus Trees from Uav Dsms

    Science.gov (United States)

    Ok, A. O.; Ozdarici-Ok, A.

    2017-05-01

    This paper presents an automated approach to detect citrus trees from digitals surface models (DSMs) as a single source. The DSMs in this study are generated from Unmanned Aerial Vehicles (UAVs), and the proposed approach first considers the symmetric nature of the citrus trees, and it computes the orientation-based radial symmetry in an efficient way. The approach also takes into account the local maxima (LM) information to verify the output of the radial symmetry. Our contributions in this study are twofold: (i) Such an integrated approach (symmetry + LM) has not been tested to detect (citrus) trees (in orchards), and (ii) the validity of such an integrated approach has not been experienced for an input, e.g. a single DSM. Experiments are performed on five test patches. The results reveal that our approach is capable of counting most of the citrus trees without manual intervention. Comparison to the state-of-the-art reveals that the proposed approach provides notable detection performance by providing the best balance between precision and recall measures.

  13. Founder lines for improved citrus biotechnology

    Science.gov (United States)

    This article discusses the research needed to develop the RMCE strategy and molecular assays for site-specific recombinases as tools for genome manipulation. Explanation of genetic engineering used to generate transgenic citrus plants to exhibit a novel phenotype, but not to contain the recombinase...

  14. Ecology of the Asian citrus pysllid

    Science.gov (United States)

    Host selection by psyllids in general appears to involve taste rather than olfaction. Adults are often less discriminating than nymphs. A priori, there is good reason to doubt that Asian citrus psyllid (ACP) uses a long-distance sex pheromone or that ACP orients to host plant volatiles over large (m...

  15. Sensitivities of baseline isolates and boscalid-resistant mutants of Alternaria alternata from pistachio to fluopyram, penthiopyrad, and fluxapyroxad

    NARCIS (Netherlands)

    Avenot, H.F.; Biggelaar, van den H.; Morgan, D.P.; Moral, J.; Joosten, M.H.A.J.; Michailides, T.J.

    2014-01-01

    Resistance of Alternaria alternata to boscalid, the first succinate dehydrogenase inhibitor (SDHI) fungicide labeled on pistachio, has become a common occurrence in California pistachio orchards and affects the performance of this fungicide. In this study, we established the baseline sensitivities o

  16. Evaluation of non-chemical seed treatment methods for the control of Alternaria dauci and A. radicina on carrot seeds

    NARCIS (Netherlands)

    Koch, E.; Schmitt, A.; Stephan, D.; Kromphardt, C.; Jahn, M.; Krauthausen, H.J.; Forsberg, G.; Werner, S.; Amein, T.; Wright, S.A.I.; Tinivella, F.; Gullino, M.L.; Roberts, S.J.; Wolf, van der J.M.; Groot, S.P.C.

    2010-01-01

    The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Contr

  17. The Asc locus for resistance to Alternaria stem canker in tomato does not encode the enzyme aspartate carbamoyltransferase

    NARCIS (Netherlands)

    Overduin, Bert; Hogenhout, Saskia A.; Biezen, Erik A. van der; Haring, Michel A.; Nijkamp, H. John J.; Hille, Jacques

    1993-01-01

    The fungal disease resistance locus Alternaria stem canker (Asc) in tomato has been suggested to encode the enzyme aspartate carbamoyltransferase (ACTase). To test this hypothesis a segment of the tomato ACTase gene was amplified by the polymerase chain reaction (PCR) using degenerate primers. The P

  18. Molecular characterization and detection of mutations associated with resistance to succinate dehydrogenase inhibiting (SDHI) fungicides in Alternaria solani

    Science.gov (United States)

    Early blight, caused by Alternaria solani, is an economically important foliar disease of potato in several production areas of the United States. Few potato cultivars possess resistance to early blight, therefore, the application of fungicides is a primary means of achieving disease control. Previo...

  19. A Zinc-Finger-Family Transcription Factor, AbVf19, Is Required for the Induction of a Gene Subset Important for Virulence in Alternaria brassicicola

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Akhil [Univ. of Hawaii, Manoa, HI (United States); Ohm, Robin A. [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Oxiles, Lindsay [Univ. of Hawaii, Manoa, HI (United States); Brooks, Fred [Univ. of Hawaii, Manoa, HI (United States); Lawrence, Christopher B. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Grigoriev, Igor V. [USDOE Joint Genome Inst., Walnut Creek, CA (United States); Cho, Yangrae [Univ. of Hawaii, Manoa, HI (United States)

    2011-10-26

    Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen with a broad host range within the family Brassicaceae. It produces secondary metabolites that marginally affect virulence. Cell wall degrading enzymes (CDWE) have been considered important for pathogenesis but none of them individually have been identified as significant virulence factors in A. brassicicola. In this study, knockout mutants of a gene, AbVf19, were created and produced considerably smaller lesions than the wild type on inoculated host plants. The presence of tandem zinc-finger domains in the predicted amino acid sequence and nuclear localization of AbVf19- reporter protein suggested that it was a transcription factor. Gene expression comparisons using RNA-seq identified 74 genes being downregulated in the mutant during a late stage of infection. Among the 74 downregulated genes, 28 were putative CWDE genes. These were hydrolytic enzyme genes that composed a small fraction of genes within each family of cellulases, pectinases, cutinases, and proteinases. The mutants grew slower than the wild type on an axenic medium with pectin as a major carbon source. This study demonstrated the existence and the importance of a transcription factor that regulates a suite of genes that are important for decomposing and utilizing plant material during the late stage of plant infection.

  20. The use of tissue culture and in vitro mutagenesis for the improvement resistance to Alternaria solani in irish potato (Solanum tuberosum L. var. Desirée

    Directory of Open Access Journals (Sweden)

    Novisel Veitía

    2001-01-01

    Full Text Available Two phases of work were carried out with the objective of obtaining somaclons in Irish Potato (Solanum tuberosum L. that present a superior behavior with respect to the variety Desirée against the early blight disease caused by Alternaria solani (Sor. and A. alternata (Fr. Keissler. In the first phase, the aspects related to the pathogen, the incubation time and the method of application of the filtered culture on the vitroplants were studied the immersion of the roots as the effective method of inoculation. The biological effectiveness of the different concentrations of the filtrate on the vitroplants of the variety Desirée (susceptible and the specie Solanum chacoense (resistant was checked, taking the dilution of 1:3 v/v as the effective for the selection. A scale was elaborated to evaluate the intensity of the damages caused by the filtrate and a selection scheme was established for the genetic improvement of the variety Desirée. The second phase had as its objective the massive inoculation with the filtered culture of the fungus 1 000 somaclons were obtained from the irradiated calli with gamma radiation. Forty-five somaclons presented levels of affectation inferior to that of the original variety. The behavior of the somaclons selected in vitro was evaluated in the greenhouse against the disease and six somaclons presented levels of affectation inferior to that of the original variety. Key words: culture filtrate, early blight, , in vitro selection

  1. Citrus tristeza virus-host interactions

    Directory of Open Access Journals (Sweden)

    William O. Dawson

    2013-05-01

    Full Text Available Citrus tristeza virus (CTV is a phloem-limited virus whose natural host range is restricted to citrus and related species. Although the virus has killed millions of trees, almost destroying whole industries, and continually limits production in many citrus growing areas, most isolates are mild or symptomless in most of their host range. There is little understanding of how the virus causes severe disease in some citrus and none in others. Movement and distribution of CTV differs considerably from that of well-studied viruses of herbaceous plants where movement occurs largely through adjacent cells. In contrast, CTV systemically infects plants mainly by long-distance movement with only limited cell-to-cell movement. The virus is transported through sieve elements and occasionally enters an adjacent companion or phloem parenchyma cell where virus replication occurs. In some plants this is followed by cell-to-cell movement into only a small cluster of adjacent cells, while in others there is no cell-to-cell movement. Different proportions of cells adjacent to sieve elements become infected in different plant species. This appears to be related to how well viral gene products interact with specific hosts. CTV has three genes that are not necessary for infection of most of its hosts, but are needed in different combinations for infection of certain citrus species. These genes apparently were acquired by the virus to extend its host range. Some specific viral gene products have been implicated in symptom induction. Remarkably, the deletion of these genes from the virus genome can induce large increases in stem pitting symptoms. The p23 gene, which is a suppressor of RNA silencing and a regulator of viral RNA synthesis, has been shown to be the cause of seedling yellows symptoms in sour orange. Most isolates of CTV in nature are populations of different strains of CTV. The next frontier of CTV biology is the understanding how the virus variants in

  2. Slight Fermentation with Lactobacillus fermentium Improves the Taste (Sugar:Acid Ratio) of Citrus (Citrus reticulata cv. chachiensis) Juice.

    Science.gov (United States)

    Yu, Yuanshan; Xiao, Gengsheng; Xu, Yujuan; Wu, Jijun; Fu, Manqin; Wen, Jing

    2015-11-01

    The aim of this study was to evaluate the hypothesis that fermentation with Lactobacillus fermentium, which can metabolize citric acid, could be applied in improving the taste (sugar:acid ratio) of citrus juice. During fermentation, the strain of L. fermentium can preferentially utilize citric acid of citrus (Citrus reticulata cv. Chachiensis) juice to support the growth without the consumption of sugar. After 6 h of fermentation with L. fermentium at 30 °C, the sugar:acid ratio of citrus juice increased to 22:1 from 12:1, which resulted in that the hedonic scores of sweetness, acidity and overall acceptability of fermented-pasteurized citrus juice were higher than the unfermented-pasteurized citrus juice. Compared with unfermented-pasteurized citrus juice, the ORAC value and total amino acid showed a reduction, and no significant change (P > 0.05) in the L*, a*, b*, total soluble phenolics and ascorbic acid (Vc) content in the fermented-pasteurized citrus juice was observed as compared with unfermented-pasteurized citrus juice. Hence, slight fermentation with L. fermentium can be used for improving the taste (sugar:acid ratio) of citrus juice with the well retaining of quality.

  3. PENDIDIKAN DAN PELATIHAN PENGENDALIAN TERPADU PENYAKIT CVPD (CITRUS VEIN PHLOEM DEGENERATION PADA PERTANAMAN JERUK DI DESA PELAGA, KECAMATAN PETANG, KABUPATEN BADUNG

    Directory of Open Access Journals (Sweden)

    WAYAN ADIARTAYASA

    2012-09-01

    Full Text Available ABSTRACT Education and training on integrated pest management (IPM of CVPD (Citrus Vein Phloem Degeneration was held at Pelaga village, Badung regency on 22 September 2005. The activities aimed to improve knowledge of the farmers about CVPD and factors influencing the intensity, insect vector and integrated pest management of CVPD. The topics convered were disease symptons, and pathogen bacteria, Diaphorina citri are as vector insect infection mechanism, disease distribubution and integrated management of CVPD. The training was attended by 26 participants from local groups of Pelaga village. The method used in activities were lectures, demonstration and practical work in the citrus field. All participants enthusiastically took part and hoped to have the next intensive traning of citrus culture.

  4. Comparative in vitro toxicity of grape- and citrus-farm dusts.

    Science.gov (United States)

    Vallyathan, Val; Pack, Donna; Leonard, Steve; Lawson, Robert; Schenker, Marc; Castranova, Vince

    2007-01-15

    Agricultural workers are exposed to a variety of airborne dusts, including crystalline silica and other inorganic minerals. This study was designed to characterize the organic and inorganic components of agricultural dusts in California grape- and citrus-farm fields and to compare their cytotoxicity using in vitro toxicity bioassays as predictors of pathogenicity. Aerosolized dusts collected from farm fields were characterized by scanning-electron-microscopic energy-dispersive x-ray analysis, x-ray diffraction, trace metal analysis by plasma emission spectroscopy, and surface area measurements. As indicators of cytotoxicity, cell viability, release of alveolar enzymes activities (lactate dehydrogenase, N-acetyl glucosaminidase), production of reactive oxygen species (ROS), such as H2O2 and hydroxyl radical (OH), and lipid peroxidation were monitored after exposure of cells to grape- and citrus-farm dusts or inorganic components of these dusts. In addition, activation of nuclear factor kappa B and activator protein-1 were evaluated at the peak time for response of 36 h postexposure. All toxicity studies were done in comparison with crystalline silica of similar particle size and diameter using the same mass concentrations as farm dusts. The results showed that inorganic minerals in the aerosolized farm dust fractions were mostly composed of aluminum silicates, crystalline silica, and free iron. Crystalline silica used in these studies was more cytotoxic than grape- and citrus-farm dusts. However, in general, citrus farm dust exhibited the greatest ability to generate ROS and induce lipid peroxidation. These results support human epidemiologic studies, reporting an increased incidence of pulmonary fibrosis in farm workers, by documenting the potential of farm dusts to induce oxidative stress and initiate disease development.

  5. Serine protease identification (in vitro) and molecular structure predictions (in silico) from a phytopathogenic fungus, Alternaria solani.

    Science.gov (United States)

    Chandrasekaran, Murugesan; Chandrasekar, Raman; Sa, Tongmin; Sathiyabama, Muthukrishnan

    2014-07-01

    Serine proteases are involved in an enormous number of biological processes. The present study aims at characterizing three-dimensional (3D) molecular architecture of serine proteases from early blight pathogen, Alternaria solani that are hypothesized to be markers of phytopathogenicity. A serine protease was purified to homogeneity and MALDI-TOF-MS/MS analysis revealed that protease produced by A. solani belongs to alkaline serine proteases (AsP). AsP is made up of 403 amino acid residues with molecular weight of 42.1 kDa (Isoelectric point - 6.51) and its molecular formula was C1859 H2930 N516 O595 S4 . AsP structure model was built based on its comparative homology with serine protease using the program, MODELER. AsP had 16 β-sheets and 10 α-helices, with Ser(350) (G347-G357), Asp(158) (D158-H169), and His(193) (H193-G203) in separate turn/coil structures. Biological metal binding region situated near 6th-helix and His(193) residue is responsible for metal binding site. Also, calcium ion (Ca(2+)) is coordinated by the carboxyl groups of Lys(84), Ile(85), Lys(86), Asp(87), Phe(88), Ala(89), Ala(90) (K84-A90) for first Ca(2+) binding site and carbonyl oxygen atom of Lys(244), Gly(245), Arg(246), Thr(247), Lys(248), Lys(249), and Ala(250) (K244-A250), for second Ca(2+) binding site. Moreover, Ramachandran plot analysis of protein residues falling into most favored secondary structures were determined (83.3%). The predicted molecular 3D structural model was further verified using PROCHECK, ERRAT, and VADAR servers to confirm the geometry and stereo-chemical parameters of the molecular structural design. The functional analysis of AsP 3D molecular structure predictions familiar in the current study may provide a new perspective in the understanding and identification of antifungal protease inhibitor designing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Effects of citrus limon essential oil (Citrus limon L. on cytomorphometric changes of Candida albicans

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    Rina Prabajati

    2017-03-01

    Full Text Available Background: The most common fungal infection found in oral cavity is oral candidiasis, largely caused by Candida species, particularly Candida albicans (C. albicans. Candida infection can get worse since it is difficult to be treated and resistant with antifungal drugs. Therefore, new drugs and compounds as well as alternative therapies involving natural sources that have antifungal activities have continually been developed. Limonene, β-pinene, and ɣ-terpinene contained in Citrus limon essential oil have been known to have quite good antifungal activities against C. albicans. Purpose: This research aimed to examine and analyze the effects of Citrus limon essential oil on cytomorphometric changes of C. albicans. Method: The research used post test only control group design. Based on the results of the pre-elementary research on antifungal activities of Citrus limon essential oil against C. albicans, Citrus limon essential oil used in this research was on concentrations of 1.56%, 1.37%, 1.17%, 0.98%, and 0.78%. Citrus limon essential oil by C. albicans inoculum and incubated for 24 hours and 48 hours. After the incubation, those C. albicans cells were fixed, dried, and then observed using a scanning electron microscopy. Result: The most effective concentrations of Citrus limon essential oil triggering cytomorphometric changes of Candida albicans were at 1.37% and 1.56% with the incubation period of 48 hours. Conclusion: C. albicans can undergo necrosis process through cytomorphometric changes after the administration of Citrus limon essential oil at concentrations of 1.56% and 1.37% with the incubation period of 48 hours.

  7. INFLUENCE OF SALINITY ON CITRUS: A REVIEW PAPER

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    ADNAN Al-Yassin

    2005-04-01

    Full Text Available Due to the rapid expansion of irrigated agriculture, effi cient use of the limited water resources in arid and semi-arid regions is becoming more and more vital. However, water salinity is a major problem due to its negative infl uence on the yields of many crops. It reduces citrus trees’ growth and causes physiological disorders. Primarily salt-stress lowers net CO2 assimilation, stomatal conductance, and water potential of citrus tree leaves, in addition to accumulation of excessive concentration of Chloride or Sodium in leaves. A great deal of research indicates that citrus have the genetic potential to be salt-sensitive; however inheritance studies in citrus are scarce. In this paper the adverse of effects of salinity on physiological aspects of citrus are reviewed. The review summarizes the prevailing state of knowledge about the responses and tolerance of citrus trees to salinity.

  8. In vitro xanthine oxidase inhibitory activity of leaves, fruits and peel extracts of Citrus aurantium, Citrus limetta and Citrus limon

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    Muthiah PL

    2012-07-01

    Full Text Available Aim of the study: To evaluate the in vitro xanthine oxidase inhibitory activity of the extract of leaves, fruits and peel of Citrus aurantium, Citrus limetta and Citrus limon.   Materials and Methods: Xanthine oxidase inhibitory activity was assayed spectrophotometrically under aerobic conditions and the degree of enzyme inhibition was determined by measuring the increase in absorbance at 295nm associated with uric acid formation.   Results: Among the extracts tested, the C.limetta peel extract exhibited highest potency of xanthine oxidase inhibition (IC50 40.16±0.88μg/ml. This was followed by C.aurantium peel (IC50 51.50±2.05μg/ml, C.limon peel (IC50 64.90±1.24μg/ml, C.aurantium leaf (IC5073.50±1.26μg/ml, C.limetta leaf (IC50 74.83±2.42μg/ml, C.limon leaf (IC50 76.83±2.02μg/ml, C.limetta fruit (IC50 95.16±0.60μg/ml extracts compared with the IC50 value of standard allopurinol was 6.6μg/ml.   Conclusion: Recent findings show that the occurrence of gout is increasing worldwide, possibly due to the changes in dietary habits like intake of food rich in nucleic acids, such as meat, sea foods, etc. Xanthine oxidase inhibitors such as allopurinol is the drug of choice, however it has been observed more side effects.  An alternative to allopurinol is the use of medicinal plants, We thus began our program to look for xanthine oxidase inhibitors of phytochemical origin. In conclusion, the study suggests that the leaves and peel extracts of Citrus aurantium, Citrus limetta and Citrus limon possess xanthine oxidase inhibitory activity that might be helpful in preventing or slowing the progress of gout and related disorders.

  9. Asian Citrus Psyllid RNAi Pathway – RNAi evidence

    OpenAIRE

    Taning, Clauvis N. T.; Eduardo C. Andrade; Hunter, Wayne B.; Olivier Christiaens; Guy Smagghe

    2016-01-01

    Diaphorina citri, known as the Asian citrus psyllid, is an important pest of citrus because it transmits a phloem-limited bacteria strongly implicated in huanglongbing (citrus greening disease). Emerging biotechnologies, such as RNA interference, could provide a new sustainable and environmentally friendly strategy for the management of this pest. In this study, genome and functional analysis were performed to verify whether the RNAi core genes are present in the Asian psyllid genome and if t...

  10. Asian Citrus Psyllid RNAi Pathway – RNAi evidence

    OpenAIRE

    Taning, Clauvis N. T.; Andrade, Eduardo C. de; Hunter, Wayne B.; Christiaens, Olivier; Smagghe, Guy

    2016-01-01

    Diaphorina citri, known as the Asian citrus psyllid, is an important pest of citrus because it transmits a phloem-limited bacteria strongly implicated in huanglongbing (citrus greening disease). Emerging biotechnologies, such as RNA interference, could provide a new sustainable and environmentally friendly strategy for the management of this pest. In this study, genome and functional analysis were performed to verify whether the RNAi core genes are present in the Asian psyllid genome and if t...

  11. Compatibility of Isaria fumosorosea (Hypocreales: Cordycipitaceae Blastospores with Agricultural Chemicals Used for Management of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae

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    Pasco B. Avery

    2013-11-01

    Full Text Available Biorational insecticides are being increasingly emphasized for inclusion in integrated pest management programs for invasive insects. The entomopathogenic fungus, Isaria fumosorosea, can be used to help manage the Asian citrus psyllid with minimal impact on beneficial arthropods, but its effectiveness may be compromised by agrochemicals used to control concurrent arthropod pests and diseases. We evaluated the compatibility of I. fumosorosea blastospores with a range of spray oils and copper-based fungicides registered for use in citrus groves. Results of laboratory and greenhouse tests showed a range of responses of the fungus to the different materials, including compatibility and incompatibility. Overall, I. fumosorosea growth in vitro was reduced least by petroleum-based materials and most by botanical oils and borax, and some of the copper-based fungicides, suggesting that tank mixing of I. fumosorosea with these latter products should be avoided. However, equivalent negative effects of test materials on fungal pathogenicity were not always observed in tests with adult psyllids. We hypothesize that some oils enhanced adherence of blastospores to the insect cuticle, overcoming negative impacts on germination. Our data show that care should be taken in selecting appropriate agrochemicals for tank-mixing with commercial formulations of entomopathogenic fungi for management of citrus pests. The prospects of using I. fumosorosea for managing the invasive Asian citrus psyllid and other citrus pests are discussed.

  12. Three New Resveratrol Derivatives from the Mangrove Endophytic Fungus Alternaria sp.

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    Jinhua Wang

    2014-05-01

    Full Text Available Three new resveratrol derivatives, namely, resveratrodehydes A–C (1–3, were isolated from the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS, 1D and 2D NMR spectroscopic data. All compounds showed broad-spectrum inhibitory activities against three human cancer cell lines including human breast MDA-MB-435, human liver HepG2, and human colon HCT-116 by MTT assay (IC50 < 50 μM. Among them, compounds 1 and 2 both exhibited marked cytotoxic activities against MDA-MB-435 and HCT-116 cell lines (IC50 < 10 μM. Additionally, compounds 1 and 3 showed moderate antioxidant activity by DPPH radical scavenging assay.

  13. Laboratory and Field Evaluation of Lupo Compound Miroemulsion(LCM) against Alternaria alternata in Tobacco

    Institute of Scientific and Technical Information of China (English)

    Lu; Jinqing; Dai; Yi; Li; Xiaoshuang; Liang; Huan; Cai; Junlong; Li; Qiang; Guo; Shengnan

    2014-01-01

    [Objective]The paper was to study effect of Lupo compound microemulsion( LCW) on Alternaria alternata. [Method]The activity of spore germination and mycelial growth was investigated by filter paper method and mycelial growth rate method,and field test was also conducted to determine the effect of LCW on tobacco plants. [Result]LCW could inhibit spore germination and mycelial growth of A. alternate. The higher concentration led to more severe reduction of sporulation and heavier inhibition against mycelial growth. When LCW was diluted into 200 times,inhibition rate of sporulation reached 91. 23%,and the inhibition rate of mycelial growth reached 93. 50%. Field test also proved that LCW had significant inhibitory effect on tobacco brown spot disease. [Conclusion]The study provided the reference for using botanical pesticide to control A. alternate in fields.

  14. First Report of Foliar Blight on Dendropanax morbifera Caused by Alternaria panax.

    Science.gov (United States)

    Deng, Jian Xin; Kim, Chang Sun; Oh, Eun Sung; Yu, Seung Hun

    2010-12-01

    Leaf spot and blight disease was observed on two-year-old seedlings of Dendropanax morbifera (Korean name: Hwangchil tree) during July of 2008 in Jindo Island, Korea. Symptoms included yellow-brown to dark brown irregularly enlarged spots frequently located along the veins of leaves. The lesions were often surrounded by chlorotic haloes. Severe leaf blight and subsequent defoliation occurred when conditions favored disease outbreak. The causal organism of the disease was identified as Alternaria panax based on morphological characteristics and sequence analysis of the internal transcribed spacer region of rDNA. A. panax isolates induced leaf spots and blight symptoms not only on D. morbifera but also on the other members of Araliaceae tested. This is the first report of foliar blight caused by A. panax on D. morbifera.

  15. Induction and selection of citrus mutant by gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Jung; Oh, Seung Kyu; Lee, Hyo Yeon [Jeju National University, Jeju (Korea, Republic of)

    2010-09-15

    We have subjected to gamma-irradiation to citrus buds and then grafted onto mature citrus tree. Mutant citrus branch lines have been induced. As a result of first selection, we found the several mutant lines showing interesting phenotypes such as higher sugar content. We have selected several branches showing good qualities such as higher sweetness and/or lower acidity. Some branch lines showed over 13 .deg. Brix sugar content and below 0.9% acidity. Other mutant branch lines showed the changes of shape, size, peel thickness, and fiber contents or distribution of fruits. The results suggest that gamma-irradiation is an effective tool for induction of citrus mutant lines.

  16. Enumerative and binomial sampling plans for citrus mealybug (Homoptera: pseudococcidae) in citrus groves.

    Science.gov (United States)

    Martínez-Ferrer, María Teresa; Ripollés, José Luís; Garcia-Marí, Ferran

    2006-06-01

    The spatial distribution of the citrus mealybug, Planococcus citri (Risso) (Homoptera: Pseudococcidae), was studied in citrus groves in northeastern Spain. Constant precision sampling plans were designed for all developmental stages of citrus mealybug under the fruit calyx, for late stages on fruit, and for females on trunks and main branches; more than 66, 286, and 101 data sets, respectively, were collected from nine commercial fields during 1992-1998. Dispersion parameters were determined using Taylor's power law, giving aggregated spatial patterns for citrus mealybug populations in three locations of the tree sampled. A significant relationship between the number of insects per organ and the percentage of occupied organs was established using either Wilson and Room's binomial model or Kono and Sugino's empirical formula. Constant precision (E = 0.25) sampling plans (i.e., enumerative plans) for estimating mean densities were developed using Green's equation and the two binomial models. For making management decisions, enumerative counts may be less labor-intensive than binomial sampling. Therefore, we recommend enumerative sampling plans for the use in an integrated pest management program in citrus. Required sample sizes for the range of population densities near current management thresholds, in the three plant locations calyx, fruit, and trunk were 50, 110-330, and 30, respectively. Binomial sampling, especially the empirical model, required a higher sample size to achieve equivalent levels of precision.

  17. Phylogenetic Analysis of Citrus tristeza virus Isolates of Wild Type Citrus in China

    Institute of Scientific and Technical Information of China (English)

    YI Long; ZHOU Chang-yong

    2014-01-01

    The genetic variation and phylogenetic relationships of Citrus tristeza virus (CTV) isolates collected from Chinese wild type citrus were analyzed by comparing the sequences of nine genomic regions (p23, p20, p13, p18, p25, p27, POL, HEL and k17) with the CTV isolates of cultivated citrus from different countries. The results showed that the divergence pattern of genomic RNA of the CTV isolates from wild type citrus was similar to that of other isolates from cultivated citrus, the 3´ proximal region was relatively conserved, and the 5´ proximal region had greater variability. The nine genomic regions of CTV isolates analyzed were found to have been under purifying selection in the evolution process. Phylogenetic analysis showed that the eleven Chinese wild CTV isolates were located at different clades and did not relfect their geographical origins, suggesting genetic diversity among the Chinese wild CTV populations. These results will aid in the understanding of molecular evolution of the Chinese CTV populations.

  18. Alternaria alternata allergens: Markers of exposure, phylogeny and risk of fungi-induced respiratory allergy.

    Science.gov (United States)

    Gabriel, Marta F; Postigo, Idoia; Tomaz, Cândida T; Martínez, Jorge

    2016-01-01

    Alternaria alternata spores are considered a well-known biological contaminant and a very common potent aeroallergen source that is found in environmental samples. The most intense exposure to A. alternata allergens is likely to occur outdoors; however, Alternaria and other allergenic fungi can colonize in indoor environments and thereby increase the fungal aeroallergen exposure levels. A consequence of human exposure to fungal aeroallergens, sensitization to A. alternata, has been unequivocally associated with increased asthma severity. Among allergenic proteins described in this fungal specie, the major allergen, Alt a 1, has been reported as the main elicitor of airborne allergies in patients affected by a mold allergy and considered a marker of primary sensitization to A. alternata. Moreover, A. alternata sensitization seems to be a triggering factor in the development of poly-sensitization, most likely because of the capability of A. alternata to produce, in addition to Alt a 1, a broad and complex array of cross-reactive allergens that present homologs in several other allergenic sources. The study and understanding of A. alternata allergen information may be the key to explaining why sensitization to A. alternata is a risk factor for asthma and also why the severity of asthma is associated to this mold. Compared to other common environmental allergenic sources, such as pollens and dust mites, fungi are reported to be neglected and underestimated. The rise of the A. alternata allergy has enabled more research into the role of this fungal specie and its allergenic components in the induction of IgE-mediated respiratory diseases. Indeed, recent research on the identification and characterization of A. alternata allergens has allowed for the consideration of new perspectives in the categorization of allergenic molds, assessment of exposure and diagnosis of fungi-induced allergies.

  19. Conidios de 'alternaria', factor de riesgo de alegria en Castilla-La Mancha

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    Silvia Sabariego Ruiz

    2007-12-01

    Full Text Available En este trabajo se estudia el comportamiento estacional de los conidios de Alternaria en la atmósfera de Castilla-La Mancha, cuyo inte- rés se basa en que los niveles en el aire de estos conidios suponen un riesgo de alergia para las personas sensibilizadas a los mismos. El estudio se ha llevado a cabo en cinco estaciones de muestreo pertenecientes a la Red de Aerobiología de Castilla-La Mancha (Red Aerocam: Albacete, Ciudad Real, Cuenca, Guadalajara y Toledo, durante el año 2008. Los captadores utilizados y la metodología de muestreo siguen las directrices de la Red Española de Aerobiología (REA. Los conidios de Alternaria se detectan en la atmósfera de Castilla-La Mancha durante todo el año, aunque los meses de mayores concentraciones se obtienen en mayo, junio y julio. Ciudad Real, Toledo y Guadalajara son las ciudades en las que se detecta una mayor concentración anual, con 5.624 conidios, 4.527 conidios y 4.173 conidios, respectivamente, seguidas de Albacete y de Cuenca. En algunas de las localidades muestreadas, los valores máximos diarios han sido elevados en un importante número de días, destacamos los registrados en Ciudad Real el 20 de marzo (722 conidios/m3, en Toledo el 18 de junio (324 conidios/m3 y en Guadalajara el 26 de junio (220 conidios/m3.

  20. Substrates and enzyme activities related to biotransformation of resveratrol from phenylalanine by Alternaria sp. MG1.

    Science.gov (United States)

    Zhang, Jinhua; Shi, Junling; Liu, Yanlin

    2013-12-01

    To identify the substrates and enzymes related to resveratrol biosynthesis in Alternaria sp. MG1, different substrates were used to produce resveratrol, and their influence on resveratrol production was analyzed using high performance liquid chromatography (HPLC). Formation of resveratrol and related intermediates was identified using mass spectrum. During the biotransformation, activities of related enzymes, including phenylalanine ammonia-lyase (PAL), trans-cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL), were analyzed and tracked. The reaction system contained 100 mL 0.2 mol/L phosphate buffer (pH 6.5), 120 g/L Alternaria sp. MG1 cells, 0.1 g/L MgSO₄, and 0.2 g/L CaSO₄ and different substrates according to the experimental design. The biotransformation was carried out for 21 h at 28 °C and 120 rpm. Resveratrol formation was identified when phenylalanine, tyrosine, cinnamic acid, and p-coumaric acid were separately used as the only substrate. Accumulation of cinnamic acid, p-coumaric acid, and resveratrol and the activities of PAL, C4H, and 4CL were identified and changed in different trends during transformation with phenylalanine as the only substrate. The addition of carbohydrates and the increase of phenylalanine concentration promoted resveratrol production and yielded the highest value (4.57 μg/L) when 2 g/L glucose, 1 g/L cyclodextrin, and phenylalanine (4.7 mmol/L) were used simultaneously.