Nayak, P.; Padmanabhan, S.Y.; Misra, S.N.
Attempts were made for induction of resistance to bacterial leaf blight in some high yielding varieties through physical and chemical mutagens. Positive results could be obtained in Padma through NMU treatments. Further studies on the induction of bacterial leaf blight resistance in the varieties Sona and Vijaya indicated that it was possible to enhance the spectrum of variability in disease reaction by mutagenic treatments. The use of genotypes, possible enhancement of recombination frequencies through treatment of hybrids in the early generation, the choice of mutagen and the screening procedures for bacterial leaf blight resistance in rice are discussed. (author)
Nakai, H.; Goto, M.
Seedlings of controls and of M 2 generation originating from the irradiation treatment of seeds of four rice varieties with thermal neutrons, 60 Co gamme-ray, ethylene-imine (EI), were inoculated with some isolates of Xanthomonas oryzae. The variability of the disease reaction in the populations arising from irradiation and chemical treatment increased both resistance and susceptibility compared with the control average, irrespective of chlorophyll mutations in M 2 . The increased variability was assumed to be due to polygenic mutations giving both germ types more resistance and more susceptibility to bacterial leaf blight. The value of the induced polygenic mutations in resistance breeding for bacterial leaf blight is briefly discussed. (author)
Blast caused by the fungus Magnaporthe oryzae (Hebert) Barr. and bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) are two major diseases of rice (Oryza sativa). The use of varietal resistance is the most appropriate strategy for controlling the diseases, and molecular assisted selection can ...
Luqman Qurata Aini
Full Text Available Recently, a new bacterial disease of maize (Zea mays was observed in Kediri, East Java, Indonesia. Infected plants showed wilt symptoms occasionally accompanied by leaf blight. This study aims to characterize the causal agent of bacterial wilt and leaf blight of maize observed in Kediri. Gram-negative, facultative anaerobic bacteria were isolated from the diseased tissues. All bacterial strains (KD1A, KB2A, KD1, KD4, KB1 gave positive result both in the hypersensitive response and pathogen-nicity assays. However, only KD1 and KB1 strains could be re-isolated from the diseased tissues. Based on several physiological and biochemical assays, the bacteria resembled Pantoea agglomerans. Moreover, the strains showed negative result on PCR amplification using HRP1d and HRP3r, a primer pair specific for detection of P. stewartii subsp. stewartii. Analysis of 16S rRNA gene sequence of KD1 and KB1 showed highest homology at 88% and 90%, respectively to P. agglomerans strain DSM 3493 (NR 0419781. The homology values were too low to conclude that the bacteria were similar to P. agglomerans. These results suggest that bacterial pathogens isolated from maize in Kediri were strains of Pantoea sp.
In search for the development of genes for resistance against bacterial leaf-blight in rice, thermal neutrons generated from the Research Reactor at the Kyoto University have been applied to the breeding. In this paper, the developmental outcome is described, and a potential application of thermal neutrons for breeding the variety of resistance against bacterial leaf-blight in rice is reviewed. When thermal neutrons were delivered to the rice, the ratio of absorbed doses by B-10, which is contained in a small quantity in the plant, was found to be larger than expected. This implies characteristic effects of thermal neutrons on the plant. When boric acid was incorporated into the plant before irradiation, the effect of thermal neutrons per irradiation time was considered to become great. The frequency of mutations for resistance was significantly higher by thermal neutron, as compared with that induced by other mutagens, such as gamma radiation, ethylene-imine, ethyl-methane-sulfonate, and nitroso-methyl-urea. Genetic analysis of mutants for resistance revealed recessive genes and polygenes. Finally, the application of thermal neutrons and other radiations would contribute greatly to a resolution of serious pollution problems in global food and environment. (N.K.)
Lucas Mateus Rivero Rodrigues
Full Text Available ABSTRACT Coffee resistance to Pseudomonas syringae pv. garcae has been associated to pleiotropic effect of SH1 allele, present in coffee plants resistant to certain races of Hemileia vastatrix, the causal agent of leaf rust, or genetic linkage between resistance alleles to both pathogens. To validate this hypothesis, 63 coffee plants in F2 generation were evaluated for resistance to 2 isolates of H. vastatrix carriers of alleles, respectively, v2, v5 (isolate I/2015 and v1; v2; v5 (isolate II/2015 with the objective to confirm presence of SH1 allele in resistant plants to isolate I/2015. The same coffee plants were evaluated for resistance to a mixture of P. syringae pv. garcae strains highly pathogenic to coffee. Results showed that, among F2 coffee allele SH1 carriers, resistant to isolate I/2015, resistant and susceptible plants to bacterial halo blight were found; the same segregation occurs between F2 homozygous for SH1 allele, susceptible to the same isolate (I/2015 of H. vastatrix. Results also indicate that there is no pleiotropic effect of gene or allele SH1 connection between genes conferring resistance to leaf rust caused by H. vastatrix and bacterial halo blight caused by P. syringae pv. garcae.
The antibacterial potential of indigenous medicinal plants as alternative chemical pesticides for controlling bacterial leaf blight (BLB) of rice was investigated. Twenty-five different species of medicinal plants were collected from various sites in Pakistan. Decoctions of all medicinal plant species were screened by the disc plate diffusion method for testing the susceptibility of an aggressive isolate of Xanthomonas oryzae pv. oryzae (Xoo 105). Out of twenty five medicinal plants, Thuja orientalis (cone + leaves), Azadirachta indica (seeds + fruits), Amomum subulatum (fruits), Terminalia chebula (fruits), Terminalia bellirica (fruits), Anethum graveolens (fruits) and Ferula assa-foetida (fruits) decoctions showed significant activity. The efficacy of decoctions from six promising plants were further tested through detached leaf, glasshouse and field assays. A decoction of Terminalia chebula demonstrated the highest effectiveness in terms of regulating BLB in the plants both under laboratory and field conditions. Bioactive fractions of Terminalia chebula were purified, characterized and tentatively identified as allegic acid. (author)
Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization
Full Text Available Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus. Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P< 0.001. Lower species richness—alpha diversity--was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression.
Full text: Seeds of the rice cultivar 'Harebare', which is susceptible to bacterial leaf blight (BLB), were treated with thermal neutrons, gamma-rays, ethyleneimine and ethylmethane-sulfonate. In the M2, plants with better resistance to BLB were identified through inoculation at the seedling and the flag leaf stages with an isolate (T7174) of the Japanese differential race I. Several mutant lines resistant to BLB were selected through tests of the M 3 or M 4 lines derived from selected resistant M 2 plants. The frequency of resistant mutants was significantly higher after the thermal neutron treatment than after treatments with other mutagens. Two mutants, which originated from the neutron treatment, showing a highly quantitative resistance to multiple BLB races were analysed for gene(s) for resistance. The resistance of one of them (M41) to the Japanese races I, II, III, IV, and V was found to be conditioned by a single recessive gene. Three other recessive genes for resistance are known, but their reaction to differential races is different. Therefore, this gene was thought to be new and was tentatively designated as xa-nm(t). The resistance of another mutant (M57) was found to be polygenically inherited. (author)
Ismachin Kartoprawiro, M.; Mugiono
Two of the most important and common rice diseases in Indonesia are bacterial leaf blight (BLB) and sheath blight (SB). The best rice yielding varieties in Indonesia, Pelita I/1 and IR5, were treated with gamma radiation and EMS. All the early maturing mutants which were selected from M 2 and M 3 generations, and afterwards in the M 8 generation we tested for their reaction to bacterial leaf blight and sheath blight. Pelita I/1 is moderately resistant to BLB and moderately susceptible to SB, but IR5 is susceptible to BLB or SB. At 30 and 60 days after transplanting, 107 early maturing mutants were inoculated with BLB. The bacteria were isolated from three different rice fields, and grown into Wakimoto media. Inoculation was done by the cutting method with suspension of 10 -7 -10 -8 cell/cm 3 . The virulence of bacteria isolated from the three fields was different. Resistant mutants were only observed in the Pelita I/1 early mutant collection; however, moderate resistance was found in the IR5 early mutants collection. At late growth stage the plant seems relatively more resistant to BLB. Early mutants of Pelita I/1 were inoculated with fungus SB following the procedure of the International Rice Sheath Blight Nursery (IRSHBN). Of 96 mutants, 55 were susceptible and 41 were moderately susceptible. Pelita I/1 was moderately susceptible with 48% damage and, compared with this, 9 mutant lines showed less than 40% damage. Selection was also carried out by natural infection; however, owing to ecoclimatic conditions the result was not convincing. (author)
Abdjad Asih Nawangsih
Full Text Available Xanthomonas oryzae pv oryzae the Causal Agent of Bacterial Leaf Blight of rice: Isolation, Characterization, and Study of Transposon Mutagenesis. X. oryzae pv. oryzae (Xoo causes bacterial leaf blight (BLB of rice (Oryza sativa L., a major disease that constrains production of the staple crop in many countries of the world. Identification of X. oryzae pv. oryzae (Xoo was conducted based on the disease symptoms, pathogenicity, morphological, physiological, and genetic characteristics of bacterial cultures isolated from the infected plants. Fifty bacterial isolates predicted as Xoo have been successfully isolated. They are aerobic, rod shaped, and Gram negative bacteria. The isolates were evaluated for their hypersensitivity in tobacco and pathogenicity in rice plant. Fifty isolates induced hypersensitive reaction in tobacco and showed pathogenicity symptom in rice in different length. Based on physiological test, hypersensitivity and pathogenicity reactions, three bacterial isolates strongly predicted as Xoo, i.e. STG21, STG42, and STG46, were non indole formation, non pigment fluorescent, hydrolyzed casein, catalase activity positive, but negative oxidase. Partial sequencing of 16S rRNA genes of STG21 and STG42 showed 80% and 82% homology with X. oryzae, respectively, while STG46 showed 84% homology with X. campestris. Mini-Tn5 transposon mutagenesis of STG21 generated one of the mutants (M5 lossed it’s ability to induce hypersensitive reaction in tobacco plant and deficient in pathogenicity on rice. The lesion length of rice leaf caused by the mutant M5 decreased up to 80%.
RATIH DEWI HASTUTI
Full Text Available Xanthomonas oryzae pv. oryzae (Xoo, a causal agent of bacterial leaf blight (BLB, is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC was not significantly different to that on control plants (P > 0.05. However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05. Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02 were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.
Padmanabhan, S.Y.; Kaur, S.; Rao, M.
The high-yielding variety, Vijaya (IR8 x T90) susceptible to bacterial leaf-blight (Xanthomonas oryzae, Uyeda and Ishiyama, Dowson) was taken up for induction of resistance to bacterial leaf-blight disease through EMS treatments. The frequency distribution of bacterial leaf blight of Vijaya (untreated) was bimodal while the frequency curves of the EMS-treated population in M 2 was polymodal, showing the introduction of new peaks, thus indicating that a wider range of variability had been induced both towards resistance and susceptibility. The seeds of ''resistant'' (R), ''moderately resistant'' (MR) and ''susceptible'' (S) selections were carried forward up to the M 6 generation. The frequency curve of bacterial leaf-blight reaction in each generation (M 3 - M 6 ) was polymodal or had a normal distribution, thus indicating that the bacterial leaf-blight reaction of the variety, Vijaya, was probably controlled by a polygenic system. Resistant plants had a very low yield potential whereas the yield range of some MR selections was the same as that of the untreated parent, and in some S selections the yield was higher than that of the parent. (author)
In 2010, a brassica leafy greens grower in Sunflower County, Mississippi, observed scattered outbreaks of a leaf blight disease on mustard greens (Brassica juncea) in a 180-hectare field. A severe outbreak of leaf blight occurred on mustard greens and turnip greens (Brassica rapa) in the same field...
Bacterial blight or leaf blight is a common disease of cotton in almost all cotton growing countries, including Tanzania. Bacterial blight is caused by infection of plants with the bacteria (Xanthomonas axonopodis pv. malvacearum) and the use of resistant cultivars is the most effective long-term strategy to manage the disease.
Dilla-Ermita, Christine Jade; Tandayu, Erwin; Juanillas, Venice Margarette; Detras, Jeffrey; Lozada, Dennis Nicuh; Dwiyanti, Maria Stefanie; Vera Cruz, Casiana; Mbanjo, Edwige Gaby Nkouaya; Ardales, Edna; Diaz, Maria Genaleen; Mendioro, Merlyn; Thomson, Michael J; Kretzschmar, Tobias
A range of resistance loci against different races of Xanthomonas oryzae pv. oryzae (Xoo), the pathogen causing bacterial blight (BB) disease of rice, have been discovered and characterized. Several have been deployed in modern varieties, however, due to rapid evolution of Xoo, a number have already become ineffective. The continuous "arms race" between Xoo and rice makes it imperative to discover new resistance loci to enable durable deployment of multiple resistance genes in modern breeding lines. Rice diversity panels can be exploited as reservoirs of useful genetic variation for bacterial blight (BB) resistance. This study was conducted to identify loci associated to BB resistance, new genetic donors and useful molecular markers for marker-assisted breeding. A genome-wide association study (GWAS) of BB resistance using a diverse panel of 285 rice accessions was performed to identify loci that are associated with resistance to nine Xoo strains from the Philippines, representative of eight global races. Single nucleotide polymorphisms (SNPs) associated with differential resistance were identified in the diverse panel and a subset of 198 indica accessions. Strong associations were found for novel SNPs linked with known bacterial blight resistance Xa genes, from which high utility markers for tracking and selection of resistance genes in breeding programs were designed. Furthermore, significant associations of SNPs in chromosomes 6, 9, 11, and 12 did not overlap with known resistance loci and hence might prove to be novel sources of resistance. Detailed analysis revealed haplotypes that correlated with resistance and analysis of putative resistance alleles identified resistant genotypes as potential donors of new resistance genes. The results of the GWAS validated known genes underlying resistance and identified novel loci that provide useful targets for further investigation. SNP markers and genetic donors identified in this study will help plant breeders in
Full Text Available Bacterial blight of cotton (Gossypium ssp., caused by Xanthomonas citri pathovar malvacearum, is a severe disease occurring in all cotton-growing areas. The interactions between host plants and the bacteria are based on the gene-for-gene concept, representing a complex resistance gene/avr gene system. In light of the recent data, this review focuses on the understanding of these interactions with emphasis on (1 the genetic basis for plant resistance and bacterial virulence, (2 physiological mechanisms involved in the hypersensitive response to the pathogen, including hormonal signaling, the oxylipin pathway, synthesis of antimicrobial molecules and alteration of host cell structures, and (3 control of the disease.
Hue Thi Nguyen
Full Text Available Bacterial leaf blight of rice (BLB, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive diseases in Asian rice fields. A high-quality rice variety, LT2, was used as the recipient parent. IRBB21, which carries the Xa21 gene, was used as the donor parent. The resistance gene Xa21 was introduced into LT2 by marker-assisted backcrossing. Three Xoo races were used to inoculate the improved lines following the clipping method. Eleven BC3F3 lines carrying Xa21 were obtained based on molecular markers and agronomic performance. The 11 lines were then inoculated with the three Xoo races. All the 11 improved lines showed better resistance to BLB than the recipient parent LT2. Based on the level of resistance to BLB and their agronomic performance, five lines (BC3F3 22.214.171.124, BC3F3 126.96.36.199, BC3F3 188.8.131.52, BC3F3 184.108.40.206 and BC3F3 220.127.116.11 were selected as the most promising for commercial release. These improved lines could contribute to rice production in terms of food security.
. atrofaciens and P. syringae pv. syringae respectively are the bacterial diseases of wheat in Iran. The disease causes damage on wheat which leads to lots of yield and crop losses in the host plants. During the spring and summer of ...
Das, Basabdatta; Sengupta, Samik; Prasad, Manoj; Ghose, Tapas Kumar
Bacterial leaf blight (BLB) caused by the vascular pathogen Xanthomonas oryzae pv. oryzae (Xoo) is one of the most serious diseases leading to crop failure in rice growing countries. A total of 37 resistance genes against Xoo has been identified in rice. Of these, ten BLB resistance genes have been mapped on rice chromosomes, while 6 have been cloned, sequenced and characterized. Diversity analysis at the resistance gene level of this disease is scanty, and the landraces from West Bengal and North Eastern states of India have received little attention so far. The objective of this study was to assess the genetic diversity at conserved domains of 6 BLB resistance genes in a set of 22 rice accessions including landraces and check genotypes collected from the states of Assam, Nagaland, Mizoram and West Bengal. In this study 34 pairs of primers were designed from conserved domains of 6 BLB resistance genes; Xa1, xa5, Xa21, Xa21(A1), Xa26 and Xa27. The designed primer pairs were used to generate PCR based polymorphic DNA profiles to detect and elucidate the genetic diversity of the six genes in the 22 diverse rice accessions of known disease phenotype. A total of 140 alleles were identified including 41 rare and 26 null alleles. The average polymorphism information content (PIC) value was 0.56/primer pair. The DNA profiles identified each of the rice landraces unequivocally. The amplified polymorphic DNA bands were used to calculate genetic similarity of the rice landraces in all possible pair combinations. The similarity among the rice accessions ranged from 18% to 89% and the dendrogram produced from the similarity values was divided into 2 major clusters. The conserved domains identified within the sequenced rare alleles include Leucine-Rich Repeat, BED-type zinc finger domain, sugar transferase domain and the domain of the carbohydrate esterase 4 superfamily. This study revealed high genetic diversity at conserved domains of six BLB resistance genes in a set of 22
Yasmin, Sumera; Hafeez, Fauzia Y.; Mirza, Muhammad S.; Rasul, Maria; Arshad, Hafiz M. I.; Zubair, Muhammad; Iqbal, Mazhar
Xanthomonas oryzae pv. oryzae (Xoo) is widely prevalent and causes Bacterial Leaf Blight (BLB) in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 μg/ mL phosphorus, produced 30 μg/mL phytohormone indole acetic acid and 15 mg/ L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693). This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin), rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs) as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM) used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The results provide
Full Text Available Xanthomonas oryzae pv. oryzae (Xoo is widely prevalent and causes Bacterial Leaf Blight (BLB in Basmati rice grown in different areas of Pakistan. There is a need to use environmentally safe approaches to overcome the loss of grain yield in rice due to this disease. The present study aimed to develop inocula, based on native antagonistic bacteria for biocontrol of BLB and to increase the yield of Super Basmati rice variety. Out of 512 bacteria isolated from the rice rhizosphere and screened for plant growth promoting determinants, the isolate BRp3 was found to be the best as it solubilized 97 μg/ mL phosphorus, produced 30 μg/mL phytohormone indole acetic acid and 15 mg/ L siderophores in vitro. The isolate BRp3 was found to be a Pseudomonas aeruginosa based on 16S rRNA gene sequencing (accession no. HQ840693. This bacterium showed antagonism in vitro against different phytopathogens including Xoo and Fusarium spp. Strain BRp3 showed consistent pathogen suppression of different strains of BLB pathogen in rice. Mass spectrometric analysis detected the production of siderophores (1-hydroxy-phenazine, pyocyanin, and pyochellin, rhamnolipids and a series of already characterized 4-hydroxy-2-alkylquinolines (HAQs as well as novel 2,3,4-trihydroxy-2-alkylquinolines and 1,2,3,4-tetrahydroxy-2-alkylquinolines in crude extract of BRp3. These secondary metabolites might be responsible for the profound antibacterial activity of BRp3 against Xoo pathogen. Another contributing factor toward the suppression of the pathogen was the induction of defense related enzymes in the rice plant by the inoculated strain BRp3. When used as an inoculant in a field trial, this strain enhanced the grain and straw yields by 51 and 55%, respectively, over non-inoculated control. Confocal Laser Scanning Microscopy (CLSM used in combination with immunofluorescence marker confirmed P. aeruginosa BRp3 in the rice rhizosphere under sterilized as well as field conditions. The
Rice varieties Ratna, Pusa 2-21, Vijaya and Pankaj have been treated with gamma rays, EMS or sodium azide to improve their resistance against blast, bacterial leaf blight or tungro virus. For blast and tungro, mutants with improved resistance were selected. Variation in reaction to bacterial leaf blight has been used in crossbreeding to accumulate genes for resistance. (author)
Outbreaks of a bacterial blight disease occurred on garlic (Allium sativum) cultivars Roxo Caxiense, Quiteria and Cacador in Southern Brazil, and threatened the main production regions of Rio Grande do Sul State. Symptoms were characterized by watersoaked reddish streaks along the leaf midrib, follo...
The study was carried out to improve bacterial leaf blight resistance in three rice cultivars (Basmati - 370, DR - 82 and IR - 6) by Agrobacterium mediated transformation system. Three week-old scutellum derived calli were infected with Agrobacterium strain EHA101, containing binary vector pTCL5 which has Xa 21 gene.
Mar 29, 2010 ... The study was carried out to improve bacterial leaf blight resistance in three rice cultivars (Basmati -. 370, DR - 82 and IR - 6) by Agrobacterium mediated transformation system. Three week-old scutellum derived calli were infected with Agrobacterium strain EHA101, containing binary vector pTCL5 which.
Chae, Jong-Chan; Hung, Nguyen Bao; Yu, Sang-Mi; Lee, Ha Kyung; Lee, Yong Hoon
Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.
Lu, Jinzhu; Ehsani, Reza; Shi, Yeyin; de Castro, Ana Isabel; Wang, Shuang
Several diseases have threatened tomato production in Florida, resulting in large losses, especially in fresh markets. In this study, a high-resolution portable spectral sensor was used to investigate the feasibility of detecting multi-diseased tomato leaves in different stages, including early or asymptomatic stages. One healthy leaf and three diseased tomato leaves (late blight, target and bacterial spots) were defined into four stages (healthy, asymptomatic, early stage and late stage) and collected from a field. Fifty-seven spectral vegetation indices (SVIs) were calculated in accordance with methods published in previous studies and established in this study. Principal component analysis was conducted to evaluate SVIs. Results revealed six principal components (PCs) whose eigenvalues were greater than 1. SVIs with weight coefficients ranking from 1 to 30 in each selected PC were applied to a K-nearest neighbour for classification. Amongst the examined leaves, the healthy ones had the highest accuracy (100%) and the lowest error rate (0) because of their uniform tissues. Late stage leaves could be distinguished more easily than the two other disease categories caused by similar symptoms on the multi-diseased leaves. Further work may incorporate the proposed technique into an image system that can be operated to monitor multi-diseased tomato plants in fields.
The study was carried out to isolate and identify fungi associated with leaf and stem blight of vanilla. The pathogens were isolated from the symptoms expressed on leaves and stem by direct tissue transplanting technique. Result showed that leaf blight was mainly associated with Colletotrichum gloeosporioides, ...
Huang, Siliang; Long, Mengling; Fu, Gang; Lin, Shanhai; Qin, Liping; Hu, Chunjin; Cen, Zhenlu; Lu, Jie; Li, Qiqin
A new banana leaf blight was found in Nanning city, China, during a 7-year survey (2003-2009) of the bacterial diseases on banana plants. Eight bacterial strains were isolated from affected banana leaves, and identified as an intraspecific taxon of Agrobacterium vitis based on their 16S rDNA sequence similarities with those of 37 randomly selected bacterial strains registered in GenBank database. The representative strain Ag-1 was virulent on banana leaves and shared similar growth and biochemical reactions with the reference strain IAM14140 of A. vitis. The strains causing banana leaf blight were denominated as A. vitis pv. musae. The traditional A. vitis strains virulent to grapevines were proposed to be revised as A. vitis pv. vitis. This is the first record of a new type of A. vitis causing banana leaf blight in China. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Padmanabhan, S.Y.; Kaur, S.; Rao, M.
The high-yield variety Vijaya ( IR 8 x T 90), susceptible to bacterial leaf blight (Xanthomonas oryzae, Uyeda and Ishiyama Dawson), was treated with EMS to induce resistance. Dehusked seeds were pre-soaked in distilled water for 4 hrs, and subjected to 0.1% and 0.2% EMS for 6 hrs. Seed germination and survival was low in 0.2% EMS. Seedlings of M 1 were raised in pots, and panicles of individual plants harvested separately. The seeds of M 2 (8800 plants) generation were grown in nursery beds, and transplanted in field after 30 days. The plants were inoculated at the boot leaf stage with X.oryzae by the clipping method, and lesion length measured 15 days later. The frequency distribution of controls was bimodal, the EMS-treated population polymodal with new peaks. A wider range of variability was induced on the resistant and susceptible side. In M 2 0.36% resistant and 0.62% moderately resistant plants occurred. The seeds of (11) resistant and (20) moderately resistant plants of M 2 were sown for M 3 generation. These plants also segregated in the range of 0-31 and 0-32 cm lesion length. The frequency distribution curve was polymodal. M 2 from ''R'' showed 1.07% of resistant plants and 0.42% from ''MR'', against, 4.28% of moderately resistant plants from ''R'' and 3.22% from ''MR''. Susceptible plants of M 2 also segregated towards resistance (1.15%) and moderately resistant (6.96%) plants in M 3 generation. Resistant (25) and moderately resistant (147) plants of M 3 were carried forward to M 4 generation, and segregated in the range of 2.1-25 cm lesion length. The frequency curve was polymodal. No resistant plant (up to 2.0 cm lesion length) could be isolated in M 4 . The percentage of moderately resistant plants was 4.44% from ''R'' of M 3 and 4.82% from ''MR'' of M 3 and 4.77% from ''S'' of M 3 generation. The yield of resistant plants was low whereas the yield of moderately resistant plants equalled the parent; the yield of susceptible segregants equalled or
Kenneth J. Jr. Kessler
Describes a canker, shoot blight, and leaf spot disease of yellow birch seedlings in the northern Great Lakes region and tells how and when trees become infected by the fungal causal agent, Gnomonia setacea.
Mar 4, 2008 ... Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is a major biotic constraint in the irrigated rice belts. Genetic resistance is the most effective and economical control for bacterial blight. Molecular survey was conducted to identify the rice germplasm/lines for the presence of Xa4, a.
Identification of bacterial blight resistance genes Xa4 in Pakistani rice germplasm using PCR. M Arif, M Jaffar, M Babar, MA Sheikh, S Kousar, A Arif, Y Zafar. Abstract. Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is a major biotic constraint in the irrigated rice belts. Genetic resistance is the most ...
Full Text Available Arrowroot (Maranta arundinacea L is a multi-functional plant used as a source of medicinal, carbohydrate (especially the green leaf type and also as ornamental plant (the streaked white leaf type. A leaf blight disease is recently found on the streaked white type in Bogor. Preliminary observation indicated that the disease was associated with bacterial infection. The cause of the disease has not been studied. This study was aimed to identify the cause of bacterial leaf blight disease. Experiments were conducted in the laboratory of Research Institute for Spice and Medicinal Crops in Bogor. Suspected bacteria were isolated from diseased leaves. The results showed that the bacterium produced white to brownish colonies on rich agar media containing peptone or cassamino acid. 3-5 mm in diameter, circular, and did not yield fluorescent pigment on King’s B medium. The bacterium formed rod cells, Gram negative, accumulated poly β hydroxybutyrate, utilized glucose under aerobic condition, not hydrolyse arginine and starch, positive catalase, insensitive to tetrazolium salt (0.1%, and grew at 35oC. The bacterium neither producted xanthomonadin pigment nor reduced nitrate to nitrite. The pathogen was tolerant to penicillin and oxolinic acid, but sensitive to streptomycin and oxytetracycline at high concentration (1.000 ppm. These characteristics met to those of Pseudomonas cepacia. Pathogenicity test on detached leaves showed that the typical symptom of blight was similar to that of natural infection on arrowroot. This is the first report on occurrence of P cepacia on arrowroot plant.
Jul 26, 2012 ... Paenibacillus polymyxa strain HKA-15, a soybean bacterial endophyte showed strong antagonism against bacterial common ... with positive chemical control in suppression of bacterial common blight disease in French bean plants. ... known to induce systemic resistance in host plant and competing out the ...
Paenibacillus polymyxa strain HKA-15, a soybean bacterial endophyte showed strong antagonism against bacterial common blight pathogen Xanthomonas campestris pv. phaseoli strains M-5 and CP-1-1. In agar diffusion assay, the antibacterial metabolite from P. polymyxa HKA-15 showed a clear zone of inhibition ...
Common bean (Phaseolus vulgaris L.) is the most important food legume among the pulses. It is a cheap source of protein, especially in Sub-Saharan Africa. However, bean production is constrained by bacterial diseases, of which common bacterial blight (Xanthomonas axonopodis p.v. phaseoli) is prevalent in Africa.
Chen, S.F.; Lombard, L.; Roux, J.; Xie, Y.J.; Wingfield, M.J.; Zhou, X.D.
Leaf blight caused by Calonectria spp. is an important disease occurring on Eucalyptus trees grown in plantations of Southeast Asia. Symptoms of leaf blight caused by Calonectria spp. have recently been observed in commercial Eucalyptus plantations in FuJian Province in Southeast China. The aim of
Ullah, I; Jamil, S; Iqbal, M Z; Shaheen, H L; Hasni, S M; Jabeen, S; Mehmood, A; Akhter, M
Aromatic basmati rice is vulnerable to bacterial blight disease. Genes conferring resistance to bacterial blight have been identified in coarse rice; however, their incorporation into basmati varieties compromises the prized basmati aroma. We identified bacterial blight resistance genes Xa4, xa5, Xa7, and xa13 in 52 basmati landraces and five basmati cultivars using PCR markers. The Xa7 gene was found to be the most prevalent among the cultivars and landraces. The cultivars Basmati-385 and Basmati-2000 also contained the Xa4 gene; however, xa5 and xa13 were confined to landraces only. Ten landraces were found to have multiple resistance genes. Landraces Basmati-106, Basmati-189 and Basmati-208 contained Xa4 and Xa7 genes. Whereas, landraces Basmati-122, Basmati-427, Basmati-433 were observed to have xa5 and Xa7 genes. Landraces Basmati-48, Basmati-51A, Basmati-334, and Basmati-370A possessed Xa7 and xa13 genes. The use of landraces containing recessive genes xa5 and xa13 as donor parents in hybridization with cultivars Basmati-385 and Basmati-2000, which contain the genes Xa4 and Xa7, will expedite efforts to develop bacterial blight-resistant basmati rice cultivars through marker assisted selection, based on a pyramiding approach, without compromising aroma and grain quality.
Common bacterial blight (CBB) caused by Xanthomonas axonopodis pv. phaseoli is an important seed-borne disease of dry beans in South Africa. Development of resistant cultivars is considered the best control measurement for the disease. Backcross breeding was used to improve BB resistance in the small white ...
Prof. Adipala Ekwamu
Common bean (Phaseolus vulgaris L.) is the most important food legume among the pulses. It is a cheap source of protein, especially in Sub-Saharan Africa. However, bean production is ... rust (Uromyces appendiculatus), common bacterial blight (Xanthomonas axonopodis p.v. phaseoli), and bean common mosaic and ...
Full Text Available Antimicrobial peptide is a polypeptide with antimicrobial activity. Antimicrobial peptide genes Np3 and Np5 from Chinese shrimp (Fenneropenaeus Chinensis were integrated into Oryza sativa L. subsp. japonica cv. Aichi ashahi by Agrobacterium mediated transformation system. PCR analysis showed that the positive ratios of Np3 and Np5 were 36% and 45% in T0 generation, respectively. RT-PCR analysis showed that the antimicrobial peptide genes were expressed in T1 generation, and there was no obvious difference in agronomic traits between transgenic plants and non-transgenic plants. Four Np3 and Np5 transgenic lines in T1 generation were inoculated with Xanthomonas oryzae pv. oryzae strain CR4, and all the four transgenic lines had significantly enhanced resistance to bacterial blight caused by the strain CR4. The Np5 transgenic lines also showed higher resistance to bacterial blight caused by strains JS97-2, Zhe 173 and OS-225. It is suggested that transgenic lines with Np5 gene might possess broad spectrum resistance to rice bacterial blight.
Full Text Available Maize (Zea mays L.; 2N=20 is major staple food crop grown worldwide adapted to several biotic and abiotic stresses. Maydis leaf blight (MLB and banded leaf and sheath blight (BLSB are serious foliar fungal diseases may cause up to 40% and 100% grain yield loss, respectively. The present studies were undertaken to work out the efficacy of chemicals, botanicals and bioagents for the management of MLB and BLSB under field condition for two seasons Kharif 2014 and 2015. Five molecules (propiconazole 25 EC, hexaconazole 25 EC, carbendazim 50 WP, mancozeb 75 WP and carbedazim 12 WP + mancozeb 63 WP, two bioagents i.e. Trichoderma harzianum and T. viridae and three botanicals namely azadirachtin, sarpagandha and bel pathar were tested for their efficacy against MLB. Eight newer fungicides viz., difenconazole 250 SC, hexaconazole 5 EC, carbendazim 50WP, validamycin 3 L, tebuconazole 250 EC, trifloxystrobin 50 WG + tebuconazole 50 WG, azoxystrobin 250 EC and pencycuron 250 SC were evaluated against BLSB. Analysis revealed significant effects of propiconazole at 0.1%, carbendazim 12 WP + mancozeb 63 WP at 0.125% and sarpagandha leaves at 10% against MLB pathogen, whereas validamycin at 0.1% and trifloxystrobin 25 WG + tebuconazole 50 WG at 0.05% were found effective against BLSB. The slow rate of disease control virtually by the bioagents might have not shown instant effect on plant response to the yield enhancing components. The identified sources of management can be used further in strengthening the plant protection in maize against MLB and BLSB.
Sahu, Sunil Kumar; Zheng, Ping; Yao, Nan
Rice (Oryza sativa) is the leading source of nutrition for more than half of the world’s population, and by far it is the most important commercial food crop. But, its growth and production are significantly hampered by the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) which causes leaf blight disease. Earlier studies have reported the antibacterial ability of FDA-approved niclosamide drug against Xoo. However, the underlying mechanism by which niclosamide blocks the growth of Xoo remained elusive. In the present study, by employing the microbiological, microscopical, molecular, bioinformatics and analytical tools we found that niclosamide can directly inhibit the growth of the Xoo by hampering the biofilm formation and the production of xanthomonadin and exopolysaccharide substances (EPS) required for relentless growth and virulence of Xoo. Interestingly, niclosamide was found to specifically suppress the growth of Xoo without affecting other bacteria like Escherichia coli. Our electron microscopic observations disclosed that niclosamide disrupts the membrane permeability of Xoo and causes the release of intracellular components. Similarly, the molecular docking analysis disclosed the molecular interaction of niclosamide with the biofilm, virulence and quorum sensing related proteins, which was further substantiated by relative gene expression analysis where niclosamide was found to significantly downregulate the expression of these key regulatory genes. In addition, considerable changes in chemical structures were detected by Fourier Transform Infrared Spectroscopy (FTIR) in response to niclosamide treatment. Overall, our findings advocate the utilization of niclosamide as a safe and potent alternative antibacterial compound to control bacterial blight disease in rice. PMID:29651297
Treikale, O; Javoisha, B; Pugacheva, E; Vigule, Z; Feodorova-Fedotova, L
In Latvia, climatic factors are influential in spreading of the Northern leaf blight of maize caused by Setosphaeria turcica (SETOTU, anamorph Exserohilum turcicum, Helminthosporium turcicum). The field experiments with the aim to investigate the effect of strobilurines to control of SETOTU in maize and the possibility to have a greening effect on yield and the silage quality parameters there were conducted in Latvian Plant Protection Research Centre in 2010. The effect of fungicides under natural and artificial infection with SETOTU on yield of maize was evaluated in 2012 and 2013. Trials designed with four replicates using randomized blocks, a plot size of 30 m2. Plots were inoculated at beginning of anthesis stage of maize by conidium of local population of H. turcicum propagated on PDA. Application of fungicides has been done in two times. Weather conditions were favourable for infestation of Northern leaf blight in maize. Disease severity was recorded according to the EPPO Guideline PP 1/272(1) on 10 plants from two central rows by 5 layers of leaves. Yield was recorded from two central separately harvested rows of each plot. The silage quality parameters in 2010 were analysed by Blgg BV Company, Netherlands. After the artificial inoculation an increase of the disease pressure in maize was observed. A good effect of the fungicides to control SETOTU was observed in all trials. No significant differences in efficacy were found between the treatments of Propulse (fluopyram 125 g L(-1), prothioconazole 125 g L(-1)), Opera (epoxiconazole 75, pyraclostrobin 199, 5 g L(-1) and Opera N (epoxiconazole 75, pyraclostrobin 102 g L(-1)). The effect of application time at the BBCH 55-59 was higher compared with application time at the BBCH 30-37. Two applications of Propulse compared with the single showed higher effect on SETOTU. The prolonged effect of Propulse on SETOTU was similar to Opera and Opera N. Greening effect was significant for all treatments compared with the
Detection of bacterial blight resistant gene xa5 using linked marker approaches. SA Naveed, M Babar, A Arif, Y Zafar, M Sabar, I Ali, M Chragh, M Arif. Abstract. Rice is the primary source of food for 57% of the world's population. Genetic resistance is important to control many kinds of pathogenic diseases. Bacterial blight ...
Key-words: bacterial blight, biological control, biodiversity, endophytic bacteria, L-form, pea, PDRl retrotransposon, Pisum sativum, Pisum abyssinicum, Pseudomonas syringae pv. pisi, race specific resistance, race non-specific resistance, Spanish landraces.
Pea bacterial blight
A. I. C. Nyaka Ngobisa
Full Text Available Hevea brasiliensis is a natural source of rubber and an important plantation tree species in Malaysia. Leaf blight disease caused by Fusicoccum substantially reduces the growth and performance of H. brasiliensis. The aim of this study was to use a combination of both morphological characteristics and molecular data to clarify the taxonomic position of the fungus associated with leaf blight disease. Fusicoccum species were isolated from infected leaves collected from plantations at 3 widely separated locations – Selangor, Perak, and Johor states – in Peninsular Malaysia in 2010. All the isolates were identified according to their conidial patterns and DNA sequences generated from internal transcribed spacers (ITS1 and ITS2, the 5.8S rRNA, and an unknown locus (BotF15 containing microsatellite repeats. Based on taxonomic and sequence data, Neofusicoccum ribis was identified as the main cause of leaf blight disease in H. brasiliensis in commercial plantations in Malaysia. A pathogenicity trial on detached leaves further confirmed that N. ribis causes leaf blight disease. N. ribis is an important leaf pathogen, and its detection in Malaysia has important implications for future planting of H. brasiliensis.
Vieira,Bruno Sérgio; Pereira,Olinto Liparini; Batista,Márcio Luiz; Barreto,Robert Weingart
Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.
Shigenobu, YOSHIDA; Takao, TSUKIBOSHI; National Institute for Agro-Environmental Sciences; National Institute for Agro-Environmental Sciences
Shoot blight and leaf spots were found on highbush blueberry trees in Tsukuba, Ibaraki, in 1999. The causal fungus was identified morphologically as Colletotrichum acutatum Simmonds ex Simmonds. This is the first report of blueberry anthracnose caused by C. acutatum in Japan.
Chen, S F; Lombard, L; Roux, J; Xie, Y J; Wingfield, M J; Zhou, X D
Leaf blight caused by Calonectria spp. is an important disease occurring on Eucalyptus trees grown in plantations of Southeast Asia. Symptoms of leaf blight caused by Calonectria spp. have recently been observed in commercial Eucalyptus plantations in FuJian Province in Southeast China. The aim of this study was to identify these Calonectria spp. employing morphological characteristics, DNA sequence comparisons for the β-tubulin, histone H3 and translation elongation factor-1α gene regions and sexual compatibility. Four Calonectria spp. were identified, including Ca. pauciramosa and three novel taxa described here as Ca. crousiana, Ca. fujianensis and Ca. pseudocolhounii. Inoculation tests showed that all four Calonectria spp. found in this study were pathogenic on two different E. urophylla × E. grandis hybrid clones, commercially utilised in eucalypt plantations in China.
Jian Xin Deng
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.
Sartori, Melina; Nesci, Andrea; García, Julián; Passone, María A; Montemarani, Analía; Etcheverry, Miriam
Eight potential biological control agents (BCAs) were evaluated in planta in order to assess their effectiveness in reducing disease severity of northern leaf blight caused by Exserohilum turcicum. The assay was carried out in greenhouse. Twenty-six-day-old plants, V4 phenological stage, were inoculated with antagonists by foliar spray. Only one biocontrol agent was used per treatment. Ten days after this procedure, all treatments were inoculated with E. turcicum by foliar application. Treatments performed were: C-Et: control of E. turcicum; T1: isolate 1 (Enterococcus genus)+E. turcicum; T2: isolate 2 (Corynebacterium genus)+E. turcicum; T3: isolate 3 (Pantoea genus)+E. turcicum; T4: isolate 4 (Corynebacterium genus)+E. turcicum; T5: isolate 5 (Pantoea genus)+E. turcicum; T6: isolate 6 (Bacillus genus)+E. turcicum; T7: isolate 7 (Bacillus genus)+E. turcicum; T8: isolate 8 (Bacillus genus)+E. turcicum. Monitoring of antagonists on the phyllosphere was performed at different times. Furthermore, the percentage of infected leaves and, plant and leaf incidence were determined. Foliar application of different bacteria significantly reduced the leaf blight between 30-78% and 39-56% at 20 and 39 days respectively. It was observed that in the V10 stage of maize plants, isolate 8 (Bacillus spp.) caused the greatest effect on reducing the severity of northern leaf blight. Moreover, isolate 8 was the potential BCA that showed more stability in the phyllosphere. At 39 days, all potential biocontrol agents had a significant effect on controlling the disease caused by E. turcicum. Copyright © 2016 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.
Rice blast caused by the fungus Magnaporthe grisea and bacterial blight (BB) caused by Xanthomonas oryzae pv. Oryzae (Xoo) are two major rice diseases in the world. An elite, early maturing maintainer line of hybrid rice, Rongfeng B hybrid rice is susceptible to both blast and BB. For improving its diseases resistance, ...
Elvira-Recuenco, M.; Bevan, J.R.; Taylor, J.D.
Resistance to pea bacterial blight (Pseudomonas syringae pv. pisi) in different plant parts was assessed in 19 Pisum sativum cultivars and landraces, carrying race-specific resistance genes (R-genes) and two Pisum abyssinicum accessions carrying race-nonspecific resistance. Stems, leaves and pods
Yihui1577 is an elite restorer line widely used in hybrid rice production in China, however, both the restorer and their derived hybrids are susceptible to bacterial blight (BB) caused by Xathomonas oryzae pv. oryzae (Xoo). In order to overcome this problem, we had introgressed two resistant genes Xa7 and Xa21 into ...
Jun 14, 2010 ... Detection of bacterial blight resistant gene xa5 using linked marker approaches. Shahzad Amir Naveed2, Muhammad Babar3*, Ajuman Arif1, Yusaf Zafar1, Muhammad Sabar1,. Iftikhar Ali2, Muhammad Chragh1 and Muhammad Arif1. 1National Institute for Biotechnology and Genetic Engineering (NIBGE), ...
Plastic shelters are thought to manage bacterial blight by protecting plants from rain and/or frost. In February to April 2008 and 2009, we studied the contribution of frost protection to efficacy of this cultural control practice. Lilacs in 1-gallon pots were exposed to four treatments: 1) plants...
N. R. LaBonte; J.R. McKenna; K. Woeste
A recently developed detached-leaf blight resistance assay has generated interest because it could reduce the amount of time needed to evaluate backcrossed hybrid trees in the American chestnut blight resistance breeding programme. We evaluated the leaf inoculation technique on a sample of advanced progeny from the Indiana state chapter American Chestnut Foundation...
Liu, Qing; Yang, Jianyuan; Yan, Shijuan; Zhang, Shaohong; Zhao, Junliang; Wang, Wenjuan; Yang, Tifeng; Wang, Xiaofei; Mao, Xingxue; Dong, Jingfang; Zhu, Xiaoyuan; Liu, Bin
This is the first report that GLP gene (OsGLP2-1) is involved in panicle blast and bacterial blight resistance in rice. In addition to its resistance to blast and bacterial blight, OsGLP2-1 has also been reported to co-localize with a QTLs for sheath blight resistance in rice. These suggest that the disease resistance provided by OsGLP2-1 is quantitative and broad spectrum. Its good resistance to these major diseases in rice makes it to be a promising target in rice breeding. Rice (Oryza sativa) blast caused by Magnaporthe oryzae and bacterial blight caused by Xanthomonas oryzae pv. oryzae are the two most destructive rice diseases worldwide. Germin-like protein (GLP) gene family is one of the important defense gene families which have been reported to be involved in disease resistance in plants. Although GLP proteins have been demonstrated to positively regulate leaf blast resistance in rice, their involvement in resistance to panicle blast and bacterial blight, has not been reported. In this study, we reported that one of the rice GLP genes, OsGLP2-1, was significantly induced by blast fungus. Overexpression of OsGLP2-1 quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. The temporal and spatial expression analysis revealed that OsGLP2-1is highly expressed in leaves and panicles and sub-localized in the cell wall. Compared with empty vector transformed (control) plants, the OsGLP2-1 overexpressing plants exhibited higher levels of H 2 O 2 both before and after pathogen inoculation. Moreover, OsGLP2-1 was significantly induced by jasmonic acid (JA). Overexpression of OsGLP2-1 induced three well-characterized defense-related genes which are associated in JA-dependent pathway after pathogen infection. Higher endogenous level of JA was also identified in OsGLP2-1 overexpressing plants than in control plants both before and after pathogen inoculation. Together, these results suggest that OsGLP2-1 functions as a positive regulator to
Full Text Available The most serious aerial disease of garlic is leaf blight caused by Stemphylium spp. Geographical variation in the causal agent of this disease is indicated. Stemphylium vesicarium has been reported in Spain, whereas S. solani is the most prevalent species recorded in China. In this study, Stemphylium isolates were obtained from symptomatic garlic plants sampled from the main Spanish production areas. Sequence data for the ITS1–5.8S–ITS2 region enabled assignation of the isolates to the Pleospora herbarum complex and clearly distinguished the isolates from S. solani. Conidial morphology of the isolates corresponded to that of S. vesicarium and clearly discriminated them from S. alfalfae and S. herbarum on the basis of the size and septation pattern of mature conidia. Conidial morphology as well as conidial length, width and length:width ratio also allowed the Spanish isolates to be distinguished from S. botryosum and S. herbarum. Control of leaf blight of garlic is not well established. Few studies are available regarding the effectiveness of chemical treatments to reduce Stemphylium spp. incidence on garlic. The effectiveness of nine fungicides of different chemical groups to reduce Stemphylium mycelial growth in vitro was tested. Boscalid + pyraclostrobin (group name, succinate dehydrogenase inhibitors + quinone outside inhibitors, iprodione (dicar-boximide, and prochloraz (demethylation inhibitors were highly effective at reducing mycelial growth in S. vesicarium with EC₅₀ values less than 5 ppm. In general, the effectiveness of the fungicide was enhanced with increasing dosage.
Brady, C L; Venter, S N; Cleenwerck, I; Engelbeen, K; de Vos, P; Wingfield, M J; Telechea, N; Coutinho, T A
This study was performed to identify bacterial strains isolated simultaneously with Pantoea species from Eucalyptus trees showing symptoms of bacterial blight and dieback in Uruguay. Several molecular techniques including 16S rRNA and rpoB gene sequencing and DNA-DNA hybridization were used to characterize the gram-negative, facultatively anaerobic, slime-producing bacterial strains isolated along with Pantoea species from Eucalyptus. Hypersensitivity reactions (HR) and pathogenicity tests were performed on tobacco and Eucalyptus seedlings, respectively. The isolates clustered closely with the type strain of Enterobacter cowanii in both phylogenetic trees constructed. The DNA-DNA similarity between the isolates and the type strain of Ent. cowanii ranged from 88% to 92%. A positive HR was observed on the tobacco seedlings, but no disease symptoms were visible on the inoculated Eucalyptus seedlings. Enterobacter cowanii was isolated from trees with symptoms of bacterial blight although strains of this bacterial species do not appear to be the causal agent of the disease. This study provides the first report of Ent. cowanii isolated from Eucalyptus. Its presence in Eucalyptus tissue suggests that it is an endophyte in trees showing symptoms of blight.
Cui, Hua; Wang, Chunlian; Qin, Tengfei; Xu, Feifei; Tang, Yongchao; Gao, Ying; Zhao, Kaijun
Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most important bacterial disease in rice (Oryza sativa L.). Our previous studies have revealed that the bacterial blight resistance gene Xa23 from wild rice O. rufipogon Griff. confers the broadest-spectrum resistance against all the naturally occurring Xoo races. As a novel executor R gene, Xa23 is transcriptionally activated by the bacterial avirulence (Avr) protein AvrXa23 via binding to a 28-bp DNA element (EBEAvrXa23) in the promoter region. So far, the evolutionary mechanism of Xa23 remains to be illustrated. Here, a rice germplasm collection of 97 accessions, including 29 rice cultivars (indica and japonica) and 68 wild relatives, was used to analyze the evolution, phylogeographic relationship and association of Xa23 alleles with bacterial blight resistance. All the ~ 473 bp DNA fragments consisting of promoter and coding regions of Xa23 alleles in the germplasm accessions were PCR-amplified and sequenced, and nine single nucleotide polymorphisms (SNPs) were detected in the promoter regions (~131 bp sequence upstream from the start codon ATG) of Xa23/xa23 alleles while only two SNPs were found in the coding regions. The SNPs in the promoter regions formed 5 haplotypes (Pro-A, B, C, D, E) which showed no significant difference in geographic distribution among these 97 rice accessions. However, haplotype association analysis indicated that Pro-A is the most favored haplotype for bacterial blight resistance. Moreover, SNP changes among the 5 haplotypes mostly located in the EBE/ebe regions (EBEAvrXa23 and corresponding ebes located in promoters of xa23 alleles), confirming that the EBE region is the key factor to confer bacterial blight resistance by altering gene expression. Polymorphism analysis and neutral test implied that Xa23 had undergone a bottleneck effect, and selection process of Xa23 was not detected in cultivated rice. In addition, the Xa23 coding region was found highly
Wei, Yunxie; Chang, Yanli; Zeng, Hongqiu; Liu, Guoyin; He, Chaozu; Shi, Haitao
With 1 AP2 domain and 1 B3 domain, 7 MeRAVs in apetala2/ethylene response factor (AP2/ERF) gene family have been identified in cassava. However, the in vivo roles of these remain unknown. Gene expression assays showed that the transcripts of MeRAVs were commonly regulated after Xanthomonas axonopodis pv manihotis (Xam) and MeRAVs were specifically located in plant cell nuclei. Through virus-induced gene silencing (VIGS) in cassava, we found that MeRAV1 and MeRAV2 are essential for plant disease resistance against cassava bacterial blight, as shown by the bacterial propagation of Xam in plant leaves. Through VIGS in cassava leaves and overexpression in cassava leave protoplasts, we found that MeRAV1 and MeRAV2 positively regulated melatonin biosynthesis genes and the endogenous melatonin level. Further investigation showed that MeRAV1 and MeRAV2 are direct transcriptional activators of 3 melatonin biosynthesis genes in cassava, as evidenced by chromatin immunoprecipitation-PCR in cassava leaf protoplasts and electrophoretic mobility shift assay. Moreover, cassava melatonin biosynthesis genes also positively regulated plant disease resistance. Taken together, this study identified MeRAV1 and MeRAV2 as common and upstream transcription factors of melatonin synthesis genes in cassava and revealed a model of MeRAV1 and MeRAV2-melatonin biosynthesis genes-melatonin level in plant disease resistance against cassava bacterial blight. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Le Clerc, Valérie; Pawelec, Anna; Birolleau-Touchard, Christelle; Suel, Anita; Briard, Mathilde
In most production areas, Alternaria leaf blight (ALB) is recognized as the most common and destructive foliage disease in carrot. To assess the genetic architecture of carrot ALB resistance, two parental coupling maps were developed with similar number of dominant markers (around 70), sizes (around 650 cM), densities (around 9.5 cM), and marker composition. The F(2:3) progenies were evaluated in field and tunnel for two scoring dates. The continuous distribution of the disease severity value indicated that ALB resistance is under polygenic control. Three QTLs regions were found on three linkage groups. Two of them were tunnel or field specific and were detected only at the second screening date suggesting that the expression of these two QTLs regions involved in resistance to Alternaria dauci might depend on environment and delay after infection.
Himaman, Winanda; Thamchaipenet, Arinthip; Pathom-Aree, Wasu; Duangmal, Kannika
In Thailand, Eucalyptus plantations rapidly expand across the country. Leaf and shoot blight caused by Cryptosporiopsis eucalypti, Cylindrocladium sp. and Teratosphaeria destructans is a serious disease in Eucalyptus plantations. In this study, a total of 477 actinomycete strains were successfully isolated from roots and rhizosphere soil of Eucalyptus. Four hundred and thirty nine isolates were classified as streptomycetes and 38 isolates were non-streptomycetes. Among these isolates, 272 (57.0%), 118 (24.7%) and 241 (50.5%) isolates were antagonistic to Cryptosporiopsis eucalypti, Cylindrocladium sp. and Teratosphaeria destructans, respectively. All isolates were tested for their abilities to produce siderophores, indole acetic acid (IAA) and solubilise phosphate. Most isolates (464, 97.3%) produced siderophores. The majority of isolates (345, 72.3%) solubilised phosphate. In addition, almost half of these isolates (237, 49.7%) produced indole acetic acid. Strain EUSKR2S82 which showed the strongest inhibitory effect against all tested fungi with plant growth promoting ability was selected to test with Eucalyptus. This strain could colonize plant roots and increase Eucalyptus roots length. In a detached leaves bioassay, the disease severity of EUSKR2S82-inoculated Eucalyptus leaves was only 30% compared to 95% in the control treatment. The 16S rRNA gene sequence analysis revealed that the strain EUSKR2S82 was related to Streptomyces ramulosus NRRL-B 2714(T) (99.44% similarity). Identification of non-streptomycete isolates using 16S rRNA gene sequences classified them into 9 genera: Actinoallomurus, Actinomadura, Amycolatopsis, Cryptosporangium, Microbispora, Micromonospora, Nocardia, Nonomuraea and Pseudonocardia. It is evident that Eucalyptus tree harbored several genera of actinomycetes. The selected isolate, EUSKR2S82 showed potential as a candidate for biocontrol agent of leaf and shoot blight of Eucalyptus and to promote growth. Copyright © 2016 Elsevier Gmb
Mar 29, 2010 ... and observed a positive effect on control of bacterial contamination in indica rice as well enhancement in calli growth. Khan et al. (2007) used 500 mg/l cefotoxime in combination with 500 mg/l carbencillin in Basmati - 370 for selection; however, Arencibia et al. (1998) used. 500mg/l cefotoxime in ...
Full Text Available In order to seek more eco-friend, economic and safer quarantine method than current methyl bromide fumigation, the convergent treatment with 200 Gy of gamma irradiation and several chemicals such as nano-siver particles (NSS, sodium dichloroisocyanurate (NaDCC was tried on the cuttings of lily in the packing of catonnage box for export. With 6 independent experiments of gamma irradiation on the three lily cultivars, cvs. Siberia, Le reve and Sorbonne, incidence and severity of lily leaf blight was investigated on leaves and petals at 8-d after infection. 200 Gy of gamma irradiation decreased at 13-25% of severity on the leaf of Sorbonne, but it increased at 2-5% of severity on the leaf of Siberia and Le reve. Chemical substitutes such as NSS and NaDCC were not effective to control of lily blight on cuttings. By 200 Gy of gamma irradiation treatment, chlorophyll contents were statistically significantly decreased at 12-d after irradiation and the longevities vaselife of fully open flower of Siberia and Sorbonne were increased at 0.4 to 1.2 days. In addition, the relative fresh weights of the gamma irradiated cuttings were severely dried compared to the non-irradiated control. On the other hands, the symptoms of phyto-toxicity of high dose gamma irradiation at 1 or 2 kGy on cv. Siberia were to be blight at the tip of bloom, bent necks of flower, and delayed the process of flowering.
Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao
Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice-growing regions in the world. The rice disease resistance (R) gene Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effector AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. 'Nipponbare' rice carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from 'CBB23' rice. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here, we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALE). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino-acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni, and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic reticulum (ER) membrane
Zhang, Fan; Wu, Zhi-Chao; Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang
Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3-59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6-10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement.
Wang, Ming-Ming; Zhang, Fan; Dingkuhn, Michael; Xu, Jian-Long; Zhou, Yong-Li; Li, Zhi-Kang
Bacterial blight, which is caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating rice diseases worldwide. The development and use of disease-resistant cultivars have been the most effective strategy to control bacterial blight. Identifying the genes mediating bacterial blight resistance is a prerequisite for breeding cultivars with broad-spectrum and durable resistance. We herein describe a genome-wide association study involving 172 diverse Oryza sativa ssp. indica accessions to identify loci influencing the resistance to representative strains of six Xoo races. Twelve resistance loci containing 121 significantly associated signals were identified using 317,894 single nucleotide polymorphisms, which explained 13.3–59.9% of the variability in lesion length caused by Xoo races P1, P6, and P9a. Two hotspot regions (L11 and L12) were located within or nearby two cloned R genes (xa25 and Xa26) and one fine-mapped R gene (Xa4). Our results confirmed the relatively high resolution of genome-wide association studies. Moreover, we detected novel significant associations on chromosomes 2, 3, and 6–10. Haplotype analyses of xa25, the Xa26 paralog (MRKc; LOC_Os11g47290), and a Xa4 candidate gene (LOC_11g46870) revealed differences in bacterial blight resistance among indica subgroups. These differences were responsible for the observed variations in lesion lengths resulting from infections by Xoo races P1 and P9a. Our findings may be relevant for future studies involving bacterial blight resistance gene cloning, and provide insights into the genetic basis for bacterial blight resistance in indica rice, which may be useful for knowledge-based crop improvement. PMID:28355306
Full Text Available X-ray irradiation with convergent chemicals such as nano-silver particles or sodium dichloroisocyanurate (NaDCC has been used to control leaf blight on cut lilies. The oriental hybrid lily cultivars Siberia, Le Reve, and Sorbonne were irradiated five times by 200 Gy of X-rays in 2014. In 2015, Siberia and Sorbonne were irradiated three times by 150 Gy of X-rays. After artificial infection with Botrytis elliptica on the leaves and petals of cut lilies, this study used convergent chemical X-ray irradiation of 200 Gy or 150 Gy. Leaf and petal blight was measured in terms of incidence and severity at 8 days after infection using total 552 cuttings. Results indicate that the treatments of X-ray irradiation and NaDCC in 2014 and 2015 slightly decreased the severity of petal blight on Siberia and Sorbonne. However, the results were not significant and severity did not decrease as NaDCC concentration increased. Vase-life was observed separately after X-ray irradiation of 270 cut lilies in 2014 and 108 cut lilies in 2015. Chlorophyll content was not affected by either 200 Gy or 150 Gy of X-rays. The number of days of fully opened flowers at Siberia of 150 Gy and Le Revu of 200 Gy increased by 1–2 days. In addition, the relative fresh weights of the X-rayed flowers were 10% drier than the non-irradiated controls. Overall, leaf blight control by X-ray was inferior to the control by gamma rays, and petal color was bleached in Sorbonne and Le Reve cvs. by 150 Gy of X-rays.
DeChant, Chad; Wiesner-Hanks, Tyr; Chen, Siyuan; Stewart, Ethan L; Yosinski, Jason; Gore, Michael A; Nelson, Rebecca J; Lipson, Hod
Northern leaf blight (NLB) can cause severe yield loss in maize; however, scouting large areas to accurately diagnose the disease is time consuming and difficult. We demonstrate a system capable of automatically identifying NLB lesions in field-acquired images of maize plants with high reliability. This approach uses a computational pipeline of convolutional neural networks (CNNs) that addresses the challenges of limited data and the myriad irregularities that appear in images of field-grown plants. Several CNNs were trained to classify small regions of images as containing NLB lesions or not; their predictions were combined into separate heat maps, then fed into a final CNN trained to classify the entire image as containing diseased plants or not. The system achieved 96.7% accuracy on test set images not used in training. We suggest that such systems mounted on aerial- or ground-based vehicles can help in automated high-throughput plant phenotyping, precision breeding for disease resistance, and reduced pesticide use through targeted application across a variety of plant and disease categories.
Full Text Available Based on the sequence of a resistance gene analog FZ14 derived from Zizania latifolia (Griseb., a pair of specific PCR primers FZ14P1/FZ14P2 was designed to isolate candidate disease resistance gene. The pooled-PCR approach was adopted using the primer pair to screen a genomic transformation-competent artificial chromosome (TAC library derived from Z. latifolia. A positive TAC clone (ZR1 was obtained and confirmed by sequence analysis. The results indicated that ZR1 consisted of conserved motifs similar to P-loop (kinase 1a, kinase 2, kinase 3a and GLPL (Gly-Leu-Pro-Leu, suggesting that it could be a portion of NBS-LRR type of resistance gene. Using Agrobacterium-mediated transformation of Nipponbare mature embryo, a total of 48 independent transgenic T0 plants were obtained. Among them, 36 plants were highly resistant to the virulent bacterial blight strain PXO71. The results indicate that ZR1 contains at least one functional bacterial blight resistance gene.
Mi, Jiaming; Yang, Dabing; Chen, Yi; Jiang, Jiefeng; Mou, Haipeng; Huang, Junbin; Ouyang, Yidan; Mou, Tongmin
Breeding two-line hybrid rice with disease resistance is an effective approach to stabilize rice yield in commercial rice production of China. We improved the blast and bacterial blight resistance of Guangzhan63-4S, an elite photoperiod- and thermo-sensitive male sterile (P/TGMS) line widely used in two-line hybrid rice, by introducing the R genes Pi2 and Xa7 conferring resistance to rice blast and bacterial blight, respectively. Through the backcrossing and gene pyramiding breeding coupled with molecular marker-assisted selection, a new P/TGMS line Hua1228S carrying Pi2, Xa7, and tms5 was developed. Based on 200,000 SNP markers by next-generation sequencing, Hua1228S covered 87.6% of the recurrent genome, as well as 4.5% of the donor genome from VE6219 and 7.9% from YR7029-39. When infected with seven tested Xanthomonas oryzae pv. oryzae strains, Hua1228S conferred high resistance (0 level) to six bacterial blight strains. Moreover, Hua1228S showed broad-spectrum resistance to rice blast isolates with a high resistance frequency of 90.91%. High levels of resistance to leaf blast and neck blast were observed under heavy disease pressure in natural field. Importantly, Hua1228S showed identical fertility-sterility alteration pattern to Guangzhan63-4S. Thus, two hybrid combinations Hua Liangyou 2821 and Hua Liangyou 284 derived from Hua1228S exhibited enhanced resistance and higher yield compared with the control variety Feng Liangyou 4. These results indicate that Hua1228S has tremendous potentiality to increase and stabilize the rice yield, through the introgression of two R genes by marker-assisted selection strategy.
Baliyan, Nikita; Malik, Rekha; Rani, Reema; Mehta, Kirti; Vashisth, Urvashi; Dhillon, Santosh; Boora, Khazan Singh
Bacterial leaf blight (BB), caused by the bacterium Xanthomonas oryzae pv. Oryzae (Xoo), is the major constraint amongst rice diseases in India. CSR-30 is a very popular high-yielding, salt-tolerant Basmati variety widely grown in Haryana, India, but highly susceptible to BB. In the present study, we have successfully introgressed three BB resistance genes (Xa21, xa13 and xa5) from BB-resistant donor variety IRBB-60 into the BB-susceptible Basmati variety CSR-30 through marker-assisted selection (MAS) exercised with stringent phenotypic selection without compromising the Basmati traits. Background analysis using 131 polymorphic SSR markers revealed that recurrent parent genome (RPG) recovery ranged up to 97.1% among 15 BC 3 F 1 three-gene-pyramided genotypes. Based on agronomic evaluation, BB reaction, aroma, percentage recovery of RPG, and grain quality evaluation, four genotypes, viz., IC-R28, IC-R68, IC-R32, and IC-R42, were found promising and advanced to BC 3 F 2 generation. Copyright © 2017 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
Rice Gen Newsl 15: 131-133. Habarurema, I., Asea, G., Lamo, J., Gibson, P.,. Edema, R., Se're,' Y. and Onasanya, R.O. 2012. Genetic analysis of resistance to rice bacterial blight in Uganda. Africa Crop Science. Journal 20 Issue Supplement sl :105-112. IRRI. 1996. Standard Evaluation System for Rice. (SES). International ...
1972-01-01In the beginning of the nineteen fifties bacterial blight caused much damage to pea crops in South Africa, particularly to those grown for seed production. A study has been made of the causal organism and the conditioning factors of the disease, special attention being paid to frost as a
Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L.) in the central and western U.S. and has been reported in Australia and Europe. The disease is not always recognized because symptoms are often associated with frost damage. Two culti...
Kottapalli, Kameswara Rao; Lakshmi Narasu, M; Jena, Kshirod K
Bacterial leaf blight (BB) of rice is a major disease limiting rice production in several rice growing regions of the world. The pathogen, Xanthomonas oryzae pv oryzae, causing the disease is highly virulent to rice crops and is capable of evolving new races. Breeding efforts to incorporate single BB resistant gene often leads to resistance breakdown within a short period. To overcome such breakdown of resistance and develop germplasm with durable disease resistance, we have introgressed three bacterial blight resistance genes, xa5, xa13, and Xa21 into a fine grain rice variety, Samba Mahsuri, using sequence tagged site (STS) markers linked to these genes. Since the efficiency of the STS markers linked to recessive genes to detect homozygotes is less than 100%, we adopted four different pyramiding schemes to minimize loss of recessive resistance genes in advanced backcross generations. Pyramiding scheme A in which a two-gene Samba Mahsuri pyramid line containing Xa21 and xa5 genes was crossed with the Samba Mahsuri line having xa13 gene alone was found to be most effective in preventing the loss of an important recessive gene xa13. We further demonstrated that there was no yield penalty due to pyramiding of multiple genes into the elite indica rice variety.
Ramalingam, Jegadeesan; Savitha, Palanisamy; Alagarasan, Ganesh; Saraswathi, Ramasamy; Chandrababu, Ranganathan
Bacterial blight (BB), caused by Xanthomonas oryzae pv .oryzae is one among the major diseases in rice, which in severe condition cause losses up to 60% in total yield. Marker assisted pyramiding of three broad spectrum BB resistance genes ( xa5, xa13 , and Xa21 ) in prominent rice varieties is the most economical and effective strategy for the management of the BB disease. We report here the pyramiding of three genes ( xa5, xa13 , and Xa21 ) in maintainer lines (CO 2B, CO 23B, and CO 24B) of three promising wild abortive cytoplasmic male sterile lines (CO 2A, CO 23A, and CO 24A) through functional markers assisted back cross breeding. IRBB60 with xa5, xa13 , and Xa21 genes is used as a donor parent. BC 2 F 1 and BC 2 F 2 generations from a cross of CO 2B, CO 23B, and CO 24B with IRBB60 were evaluated for bacterial blight and non-fertility restoration. In BC 2 F 1 , plants with all three resistance genes ( xa5, xa13 , and Xa21 ) and high parent genome recovery was identified. In BC 2 F 2 , plants with all resistance genes and without fertility restorer ( Rf3 and Rf4 ) were selected. Based on agronomic traits, BB resistance and maintenance of sterility, two plants each in CO 2B × IRBB60, CO 24B × IRBB60 and one plant in CO 23B × IRBB60 combinations were identified. The identified lines were crossed with respective male sterile lines for conversion of improved B line into CMS line through back-crossing, in addition to selfing. The plants with high recurrent genome and phenotypically similar to parental lines and sterile are being used for the hybrid rice development program. Currently, using these lines (improved CMS line), test crosses were made to develop new rice hybrids. Hybrids combinations viz. , CO 23A × AD08009R and CO 24A × IET20898R were found to be stable at different locations with high yield. The R line used in this study has been introgressed with xa5, xa13 , and Xa21 genes in a separate breeding program. These new hybrids with resistance against
Full Text Available Bacterial blight (BB, caused by Xanthomonas oryzae pv.oryzae is one among the major diseases in rice, which in severe condition cause losses up to 60% in total yield. Marker assisted pyramiding of three broad spectrum BB resistance genes (xa5, xa13, and Xa21 in prominent rice varieties is the most economical and effective strategy for the management of the BB disease. We report here the pyramiding of three genes (xa5, xa13, and Xa21 in maintainer lines (CO 2B, CO 23B, and CO 24B of three promising wild abortive cytoplasmic male sterile lines (CO 2A, CO 23A, and CO 24A through functional markers assisted back cross breeding. IRBB60 with xa5, xa13, and Xa21 genes is used as a donor parent. BC2F1 and BC2F2 generations from a cross of CO 2B, CO 23B, and CO 24B with IRBB60 were evaluated for bacterial blight and non-fertility restoration. In BC2F1, plants with all three resistance genes (xa5, xa13, and Xa21 and high parent genome recovery was identified. In BC2F2, plants with all resistance genes and without fertility restorer (Rf3 and Rf4 were selected. Based on agronomic traits, BB resistance and maintenance of sterility, two plants each in CO 2B × IRBB60, CO 24B × IRBB60 and one plant in CO 23B × IRBB60 combinations were identified. The identified lines were crossed with respective male sterile lines for conversion of improved B line into CMS line through back-crossing, in addition to selfing. The plants with high recurrent genome and phenotypically similar to parental lines and sterile are being used for the hybrid rice development program. Currently, using these lines (improved CMS line, test crosses were made to develop new rice hybrids. Hybrids combinations viz., CO 23A × AD08009R and CO 24A × IET20898R were found to be stable at different locations with high yield. The R line used in this study has been introgressed with xa5, xa13, and Xa21 genes in a separate breeding program. These new hybrids with resistance against bacterial blight
Ramalingam, Jegadeesan; Savitha, Palanisamy; Alagarasan, Ganesh; Saraswathi, Ramasamy; Chandrababu, Ranganathan
Bacterial blight (BB), caused by Xanthomonas oryzae pv.oryzae is one among the major diseases in rice, which in severe condition cause losses up to 60% in total yield. Marker assisted pyramiding of three broad spectrum BB resistance genes (xa5, xa13, and Xa21) in prominent rice varieties is the most economical and effective strategy for the management of the BB disease. We report here the pyramiding of three genes (xa5, xa13, and Xa21) in maintainer lines (CO 2B, CO 23B, and CO 24B) of three promising wild abortive cytoplasmic male sterile lines (CO 2A, CO 23A, and CO 24A) through functional markers assisted back cross breeding. IRBB60 with xa5, xa13, and Xa21 genes is used as a donor parent. BC2F1 and BC2F2 generations from a cross of CO 2B, CO 23B, and CO 24B with IRBB60 were evaluated for bacterial blight and non-fertility restoration. In BC2F1, plants with all three resistance genes (xa5, xa13, and Xa21) and high parent genome recovery was identified. In BC2F2, plants with all resistance genes and without fertility restorer (Rf3 and Rf4) were selected. Based on agronomic traits, BB resistance and maintenance of sterility, two plants each in CO 2B × IRBB60, CO 24B × IRBB60 and one plant in CO 23B × IRBB60 combinations were identified. The identified lines were crossed with respective male sterile lines for conversion of improved B line into CMS line through back-crossing, in addition to selfing. The plants with high recurrent genome and phenotypically similar to parental lines and sterile are being used for the hybrid rice development program. Currently, using these lines (improved CMS line), test crosses were made to develop new rice hybrids. Hybrids combinations viz., CO 23A × AD08009R and CO 24A × IET20898R were found to be stable at different locations with high yield. The R line used in this study has been introgressed with xa5, xa13, and Xa21 genes in a separate breeding program. These new hybrids with resistance against bacterial blight will increase
Verma, J P; Formanek, H
Mureins were isolated from two strains of Xanthomonas malvacearum, a phytopathogenic bacterium causing bacterial blight of cotton. The purity of murein was 70-95 % and the amino acid and amino sugar components (glutamic acid, alanina, meso-disminopimelic acid, muramic acid and glucosamine) were present at the molar ratio of 1:1.9:1:l.12.0.85. The bacterium secreted a copious amount of slime which masked itd surface structure. The slime was composed of densley interwoven network of filamentous material originating from the cell surface and extended into the medium without and discernable boundary. The slime was secreted through surface layers pores by force, giving the effect of a spray or jet. Slime also played a role in chain formatin of baterial cells.
Essenberg, Margaret; Bayles, Melanie B; Pierce, Margaret L; Verhalen, Laval M
Near-isogenic lines of upland cotton (Gossypium hirsutum) carrying single, race-specific genes B4, BIn, and b7 for resistance to bacterial blight were used to develop a pyramid of lines with all possible combinations of two and three genes to learn whether the pyramid could achieve broad and high resistance approaching that of L. A. Brinkerhoff's exceptional line Im216. Isogenic strains of Xanthomonas axonopodis pv. malvacearum carrying single avirulence (avr) genes were used to identify plants carrying specific resistance (B) genes. Under field conditions in north-central Oklahoma, pyramid lines exhibited broader resistance to individual races and, consequently, higher resistance to a race mixture. It was predicted that lines carrying two or three B genes would also exhibit higher resistance to race 1, which possesses many avr genes. Although some enhancements were observed, they did not approach the level of resistance of Im216. In a growth chamber, bacterial populations attained by race 1 in and on leaves of the pyramid lines decreased significantly with increasing number of B genes in only one of four experiments. The older lines, Im216 and AcHR, exhibited considerably lower bacterial populations than any of the one-, two-, or three-B-gene lines. A spreading collapse of spray-inoculated AcBIn and AcBInb7 leaves appears to be a defense response (conditioned by BIn) that is out of control.
Jay Ram Lamichhane
Full Text Available Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012. The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1% to very high (almost 75% across the orchards. Young plants (4-year old were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.
Roberto dos Santos Trindade
Full Text Available Common bacterial blight (CBB, which is caused by Xanthomonas axonopodis pv. phaseoli (Xap, is the main bacterial disease in snap beans and controlling this disease using resistant cultivars is still a challenge. This work aimed to study the combining ability for CBB resistance in Phaseolus vulgaris genotypes. Six parents (two genotypes of CBB-resistant dry bean and four susceptible snap bean accessions were crossed in a complete diallel scheme without reciprocals to estimate the general and specific ability to Xap resistance. CBB resistance was evaluated by the inoculation with two Xap isolates, and its severity was evaluated based on the four following resistance components: area under the disease progress curve; scores in the leaves; latent period and diameter of pod lesion. Differences between the two isolates were observed considering all the disease components. Besides pathogen variability, significant GCA and SCA indicate that additive and non-additive effects are involved in Xap-resistance control for the evaluated genotypes, implying that CBC resistance is a trait with complex inheritance. For breeding purposes, the result demonstrates the need to apply breeding methods that are focused on advanced generations selection.
Full Text Available Several bacterial strains were isolated from different rhizospheres. Among these, strain PDY7 exhibited strong antibacterial activity against the rice bacterial blight (BB pathogen Xanthomonas oryzae pv. oryzae (Xoo by the laboratory dual plate assays. The antibacterial property of the strain PDY7 was further investigated for the production of 2,4-diacetylphloroglucinol (DAPG, which amplified a characteristic of 629-bp DNA fragment by PCR-based screening method using phlD primers. The application of phlD positive strains was carefully evaluated for disease control and growth promotion of rice plants under field conditions. The selected strain PDY7 suppressed the rice BB by 58.83% and 51.88% under glass house and field conditions, respectively. In addition, the strain PDY7 showed significant two-fold increase in root length (18.08 cm, shoot length (29.81 cm, and grain yield (96.07 g. Strain PDY7 promoted the growth of rice plants by production of indole-3-acetic acid (IAA, which was determined by high performance liquid chromatography (HPLC analysis. Our findings suggest that PDY7 belongs to the P. fluorescens group and can serve as potential biocontrol of BB as well as biofertilizer agent for growth promotion of rice.
Tchameni, Séverin Nguemezi; Mbiakeu, Staelle Njamou; Sameza, Modeste Lambert; Jazet, Pierre Michel Dongmo; Tchoumbougnang, François
The aim of this work was to evaluate the antimicrobial activities of leaves and epicarp of Citrus aurantifolia essential oil against Phytophthora colocasiae, the causative agent of taro leaf blight. Oils were extracted by hydrodistillation, and their chemical composition was determined by gas chromatography and gas chromatography coupled with mass spectrometry. Antimicrobial activities of oils were tested in vitro against mycelium growth and sporangium production. In situ tests were done on healthy taro leaves, and the necrosis symptoms were evaluated. Results showed that the essential oil extraction yields from leaves and epicarp were 0.61 and 0.36%, respectively. Limonene (48.96%), bornyl acetate (14.18%), geraniol (10.53%), geranial (3.93%), and myrcene (3.14%) were the main components in leaf oil, while limonene (59.09%), cis-hydrate sabinene (7.53%), geranial (5.61%), myrtenol (5.02%), and terpinen-4-ol (3.48%) were the main components in epicarp oil. Both oils exhibited antimicrobial activities with total inhibition of the mycelium growth at 500 and 900 ppm for leaf and epicarp, respectively. The highest inhibitory concentration of sporangium production was 400 (72.84%) and 800 ppm (80.65%) for leaf and epicarp oil, respectively. For the standard fungicide (metalaxyl), the total inhibition value of mycelial growth and sporangium production was 750 ppm. In situ tests showed that, at 5000 ppm, total inhibition (100%) was obtained for a preventive test, while 50% of the inhibition was observed for a curative test when leaf oil was applied. When epicarp essential oil was applied at 5000 ppm, 47.5 and 16.66% of the reduction of leaf necrosis were observed for the preventive and curative test, respectively. There were positive correlations between both the oil concentration and the reduction of necrosis caused by P. colocasiae. These findings suggest that the C. aurantifolia essential oil could serve as an eco-friendly biocontrol for the management of taro
Agrawal, P.K.; Gosal, S.S.; Sidhu, G.S.
Rice is the most important cereal crop in the world feeding more than 50 percent of the human population. During the last 30 years, induced mutation breeding has played a significant role in rice breeding programmes. Rice mutants with higher yield, greater tolerance to diseases and pests and other agronomic qualities have been released for commercial cultivation in many countries. Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae is the second important disease in Southeast Asia. In the Basmati field sometime the yield loss is up to 100%. Moreover, there is no resistance source available. In Basmati rice, which is known for its quality and aroma. Induction of bacterial blight resistance in Basmati will help in developing high yielding Basmati type cultivars without compromising the quality
Brassica leafy greens (Brassica juncea and Brassica rapa) represent one of the most economically important vegetable crop groups in the southeastern United States. In the last 10 years, numerous occurrences of a leaf blight disease on these leafy vegetables have been reported in several states. One ...
Alfonso, A.A.; Avellanoza, E.S.; Miranda, R.T.; Espejo, E.O.; Garcia, N.S.
Mutant lines derived from gamma radiation-treated commercial variety NSIC RC144 were produced and screened for novel resistance to bacterial blight, one of the most serious diseases of rice. Preliminary screening of a bulk M2 population through induced method using race 3 of the pathogen Xanthomonas oryzae pv. oryzae (Xoo) resulted in the selection of 89 resistant plants. Subsequent repeated bacterial blight screenings and generation advance for five seasons resulted in the selection of two highly resistant M7 sister lines whose origin can be traced to a single M2 plant. DNA fingerprinting using 63 genome-wide simple sequence repeat (SSR) markers revealed an identical pattern in these lines. Using the same set of markers, they also exhibited 98% similarity to wild type NSIC RC144 indicating that the resistance is due to mutation and not due to genetic admixture or seed impurity. Two seasons of bacterial blight screening using 14 local isolates representing ten races of Xoo revealed an identical reaction pattern in these lines. The reaction pattern was observed to be unique compared to known patterns in four IRBB isolines (IRBB 4, 5, 7 and 21) with strong resistant reaction to bacterial blight suggesting possible novel resistance. The susceptible reaction in F1 testcrosses using Xoo race 6 and the segregation patterns in two F2 populations that fit with the expected 3 susceptible: 1 resistant ratio (P = 0.4, ns) suggest a single-gene recessive mutation in these lines. These mutants are now being used as resistance donor in the breeding program while further molecular characterization to map and characterize the mutated gene is being pursued
Xi Ning; Yao Sun; Changchun Wang; Weilin Zhang; Meihao Sun; Haitao Hu; Jianzhong Liu; Ling Yang
Glutaredoxins (GRXs) belong to the antioxidants involved in the cellular stress responses. In spite of the identification 48 GRX genes in rice genomes, the biological functions of most of them remain unknown. Especially, the biological roles of members of GRX family in disease resistance are still lacking. Our proteomic analysis found that OsGRX20 increased by 2.7-fold after infection by bacterial blight. In this study, we isolated and characterized the full-length nucleotide sequences of the...
Zhao, Hui; Jiang, Jing; Li, Kailong; Liu, Guifeng
WRKY transcription factors (TFs) are important regulators in the complex stress response signaling networks in plants, but the detailed mechanisms underlying these regulatory networks have not been fully characterized. In the present study, we identified a Group III WRKY gene (PsnWRKY70, Potri.016G137900) from Populussimonii × Populusnigra and explored its function under salt and pathogen stresses. The promoter sequence that is located 2471-bp upstream from the start codon (SC) of PsnWRKY70 contained many stress-responsive cis-elements. Yeast one-hybrid assay suggested the upstream regulators, PsnWRKY70, PsnNAM (Potri.009G141600), PsnMYB (Potri.006G000800) and PsnGT1 (Potri.010G055000), probably modulate the expression of the PsnWRKY70 gene by specifically binding to the W-box or GT1GMSCAM4 (GT1) element. Yeast two-hybrid assay and transcriptome analysis revealed that HP1 (Potri.004G092100), RRM (Potri.008G146700), Ulp1 (Potri.002G105700) and some mitogen-activated protein kinase cascade members probably interact with PsnWRKY70 TF to response to salt stress. Compared with non-transgenic (NT) plants, PsnWRKY70-overexpressing (OEX) plants exhibited improved leaf blight disease resistance, while PsnWRKY70-repressing (REX) plants displayed enhanced salt stress tolerance. PsnWRKY70, PsnNAM, PsnMYB and PsnGT1 exhibited similar expression patterns in NT under salt and leaf blight disease stresses. The differentially expressed genes (DEGs) from NT vs OEX1 and the DEGs from NT vs REX1 exhibited considerable diversification. Most of the DEGs between NT and OEX1 were involved in aromatic amino acid biosynthesis, secondary metabolism, programmed cell death, peroxisomes and disease resistance. Most of the DEGs between NT and REX1 were related to desiccation response, urea transmembrane transport, abscisic acid response, calcium ion transport and hydrogen peroxide transmembrane transport. Our findings not only revealed the salt stress response signal transduction pathway of Psn
Anne Z Phillips
Full Text Available Cotton bacterial blight (CBB, an important disease of (Gossypium hirsutum in the early 20th century, had been controlled by resistant germplasm for over half a century. Recently, CBB re-emerged as an agronomic problem in the United States. Here, we report analysis of cotton variety planting statistics that indicate a steady increase in the percentage of susceptible cotton varieties grown each year since 2009. Phylogenetic analysis revealed that strains from the current outbreak cluster with race 18 Xanthomonas citri pv. malvacearum (Xcm strains. Illumina based draft genomes were generated for thirteen Xcm isolates and analyzed along with 4 previously published Xcm genomes. These genomes encode 24 conserved and nine variable type three effectors. Strains in the race 18 clade contain 3 to 5 more effectors than other Xcm strains. SMRT sequencing of two geographically and temporally diverse strains of Xcm yielded circular chromosomes and accompanying plasmids. These genomes encode eight and thirteen distinct transcription activator-like effector genes. RNA-sequencing revealed 52 genes induced within two cotton cultivars by both tested Xcm strains. This gene list includes a homeologous pair of genes, with homology to the known susceptibility gene, MLO. In contrast, the two strains of Xcm induce different clade III SWEET sugar transporters. Subsequent genome wide analysis revealed patterns in the overall expression of homeologous gene pairs in cotton after inoculation by Xcm. These data reveal important insights into the Xcm-G. hirsutum disease complex and strategies for future development of resistant cultivars.
Full Text Available Nucleotide sequence polymorphisms among R gene alleles influence the process of co-evolutionary interaction between host and pathogen by shaping the response of host plants towards invading pathogens. Here, we present the DNA sequence polymorphisms and diversities present among natural alleles of three rice bacterial blight resistance genes, Xa21, Xa26 and xa5. The diversity was examined across different wild relatives and cultivars of Oryza species. Functional significance of selected alleles was evaluated through semi-quantitative reverse transcription polymerase chain reaction and real time PCR. The greatest nucleotide diversity and singleton variable sites (SVS were present in Xa26 (π = 0.01958; SVS = 182 followed by xa5 and Xa21 alleles. The highest frequency of single nucleotide polymorphisms were observed in Xa21 alleles and least in xa5. Transition bias was observed in all the genes and 'G' to 'A' transitions were more favored than other form of transitions. Neutrality tests failed to show the presence of selection at these loci, though negative Tajima's D values indicate the presence of a rare form of polymorphisms. At the interspecies level, O. nivara exhibited more diversity than O. sativa. We have also identified two nearly identical resistant alleles of xa5 and two sequentially identical alleles of Xa21. The alleles of xa5 showed basal levels of expression while Xa21 alleles were functionally not expressed.
Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Pandit, Elssa; Behera, Lambodar; Anandan, Annamalai; Mukherjee, Arup Kumar; Lenka, Srikanta; Barik, Durga Prasad
Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv. oryzae is a major disease of rice in many rice growing countries. Pyramided lines carrying two BB resistance gene combinations (Xa21+xa13 and Xa21+xa5) were developed in a lowland cultivar Jalmagna background through backcross breeding by integrating molecular markers. In each backcross generation, markers closely linked to the disease resistance genes were used to select plants possessing the target genes. Background selection was continued in those plants carrying resistant genes until BC(3) generation. Plants having the maximum contribution from the recurrent parent genome were selected in each generation and hybridized with the recipient parent. The BB-pyramided line having the maximum recipient parent genome recovery of 95% was selected among BC3F1 plants and selfed to isolate homozygous BC(3)F(2) plants with different combinations of BB resistance genes. Twenty pyramided lines with two resistance gene combinations exhibited high levels of tolerance against the BB pathogen. In order to confirm the resistance, the pyramided lines were inoculated with different X. oryzae pv. oryzae strains of Odisha for bioassay. The genotypes with combination of two BB resistance genes conferred high levels of resistance to the predominant X. oryzae pv. oryzae isolates prevalent in the region. The pyramided lines showed similarity with the recipient parent with respect to major agro-morphologic traits.
Jing WANG,Chen CHENG,Yanru ZHOU,Yong YANG,Qiong MEI,Junmin LI,Ye CHENG,Chengqi YAN,Jianping CHEN
Full Text Available Y73 is a progeny of asymmetric somatic hybridization between Oryza sativa cv. Dalixiang and the wild rice species Oryza meyeriana. Inoculation with a range of strains of Xanthomonas oryzae pv. oryzae showed that Y73 had inherited a high level of resistance to rice bacterial blight (BB from its wild parent. An F2 population of 7125 individuals was constructed from the cross between Y73 and a BB-susceptible cultivar IR24. After testing 615 SSR and STS markers covering the 12 rice chromosomes, 186 markers were selected that showed polymorphism between Y73 and IR24. Molecular markers linked to the BB resistance genes in Y73 were scanned using the F2 population and the polymorphic markers. The SSR marker RM128 on chromosome 1, the STS marker R03D159 on chromosome 3 and the STS marker R05D104 on chromosome 5 were found to be linked to the rice BB resistance genes in Y73.
Lee, Gun Woong; Chung, Moon-Soo; Kang, Mihyung; Chung, Byung Yeoup; Lee, Sungbeom
Rice bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is a severe disease of rice plants. Upon pathogen infection, rice biosynthesizes phytoalexins, including diterpenoids such as momilactones, phytocassanes, and oryzalexins. However, information on headspace volatiles in response to Xoo infection is limited. We have examined headspace volatile terpenes, induced by the infection of Xoo, and investigated their biological roles in the rice plant. Monoterpenes α-thujene, α-pinene, sabinene, myrcene, α-terpene, and (S)-limonene and sesquiterpenes cyclosativene, α-copaene, and β-elemene were detected from 1-week-old Xoo-infected rice seedlings, by solid-phase microextraction-gas chromatography-mass spectrometry. All monoterpenes were constitutively released from rice seedlings before Xoo infection. However, (S)-limonene emission was further elicited after exposure of the seedlings to Xoo in coincidence with upregulation of limonene synthase gene (OsTPS20) transcripts. Only the stereospecific (S)-limonene [and not (R)-limonene or other monoterpenes] severely inhibited Xoo growth, as confirmed by disc diffusion and liquid culture assays. Rice seedlings showed suppressed pathogenic symptoms suggestive of resistance to Xoo infection after foliar treatment with (S)-limonene. Collectively, our findings suggest that (S)-limonene is a volatile phytoanticipin, which plays a significant role in suppressing Xoo growth in rice seedlings.
Full Text Available Dithiocarbamate fungicides such as maneb and mancozeb are widely used nonsystemic protectant fungicides to control various plant fungal diseases. Dithiocarbamate fungicides should be frequently applied to achieve optimal efficacy of disease control and avoid either decline in effectiveness or wash-off from leaf surface. Dithiocarbamates are of low resistance risk but have the potential to cause human neurological diseases. The objective of this study was to develop a strategy to effectively control plant disease with reduced use of dithiocarbamtes. Southern corn leaf blight was the model pathosystem for the investigation. When corn plants were drench-treated with Bacillus cereus C1L, a rhizobacterium able to induce systemic resistance in corn plants against southern leaf blight, frequency of spraying dithiocarbamate fungicides could be decreased. The treatment of B. cereus C1L was able to protect maize from southern leaf blight while residues of dithiocarbamates on leaf surface were too low to provide sufficient protection. On the other hand, frequent sprays of mancozeb slightly but significantly reduced growth of corn plants under natural conditions. In contrast, application of B. cereus C1L can significantly promote growth of corn plants whether sprayed with mancozeb or not. Our results provide the information that plant disease can be well controlled by rhizobacteria-mediated induced systemic resistance in combination with reduced but appropriate application of dithiocarbamate fungicides just before a heavy infection period. An appropriate use of rhizobacteria can enhance plant growth and help plants overcome negative effects caused by dithiocarbamates.
Full Text Available Rhizoctonia solani Kuhn. causing banded leaf and sheath blight diseases is one of the important fungi of corn world wide. The fungus is commonly controlled by using fungicide because no resistant variety available. The objective of the study was to develop a seed treatment formulation of the selected Bacillus subtilis to control R. solani in corn. The study was conducted in the Department of Plant Pathology, College of Agriculture, University of the Philippines Los Bañòs, College, Laguna from May 2004 to August 2005, using sweet corn var. IPB Supersweet as test plant. Corn seeds were surface sterilized for 10 minutes in 1% sodium hypochlorite solution and 5% ethanol, washed thrice with sterile distilled water and air-dried. The seeds were coated with formulated B. subtilis BR23 and used for several experiments, such as evaluation for their germination and growth in the laboratory, effectively on R. solani in the baked and nonbaked field soil under greenhouse condition, and in the microplots artificially infested with R. solani. The treatment was compared with other standard seed treatment of synthetic fungicides such as captan (10 g per kg seeds and metalaxyl (10 g per kg seeds. The experiments were designed in a completely random design with three replications. Parameters observed were seed germination, plant height, disease scores, and plant yield. Laboratory formulated B. subtilis BR23 used as seed treatment had no detrimental effects on seed germination and seedling vigor. In microplots artificially infested with a selected highly virulent R. solani, seed treatment with the same formulation increased grain yield by 27% compared to that of the control captan seed treatment with 14.4%. The studies showed the potential of B. subtilis BR23 for commercialization as a seed treatment for the control of banded leaf and sheath blight disease (R. solani in corn.
Full Text Available Bacterial blight is one of the most serious diseases affecting Persian walnut (Juglans regia L.. Susceptibility to this disease was evaluated by artificial inoculation in an in vitro experiment for cultivars developed in Hungary and for selections from Transylvania. Thirty pieces of immature fruit of 11 walnut cultivars and 10 selections were inoculated by punction using a suspension containing a mixture of Xaj-isolates of controlled virulence. As control, a moderate resistant (mR ‘Pedro’ and a highly susceptible (hS ‘Milotai intenzív’ cultivars were used. After ten days the diameter of the necrotic area around the inoculation points was measured and the disease rate (DR was noted. For the calculation of indexes it was taken the structure of the lesions (diffuse or defined margin into consideration. None of the 21 cultivars/selections analysed were found to be hardly resistant, although all of them showed a higher degree of resistance than the susceptible control (‘Milotai intenzív’. The majority of the analysed cultivars fit into the moderate susceptible (mS and moderate resistant (mR group. ‘Milotai kései’ and SZEN-10, had a notable reaction as considered to be moderate resistant (mR, showed a similar degree of resistance compared to the control cultivar ‘Pedro’. It was concluded that these cultivars, based on their resistance to Xanthomonas arboricola pv. juglandis, could be proposed as resistance gene sources, as well as for production purposes in the environmental conditions of the Carpathian Basin.
Full Text Available Gamma irradiation and its convergence with nano-silver particles and sodium dichloroisocyanurate (NaDCC were investigated to inhibit germination and mycelial growth of Botrytis elliptica, the pathogen of lily leaf blight. In addition, the same treatments were studied on the process of disease development with detached leaf of lily cv. Siberia. Spray inoculation, which is closer to natural infection than wound inoculation, can be a way to investigate infection ability of the treated pathogen. The irradiating dose required to reduce the population by 90%, D10, was 526 Gy irradiating with 0-2000 Gy gamma ray on the conidial suspension as well as the growing mycelia. Even at 2000 Gy, the mycelium was not killed but just delayed its growth at 1–2 days behind. Convergent treatment with 40 mg/l of NaDCC just before 200 Gy gamma irradiation was the best way to decrease the conidial germination about 1/1000 times. The control values of gamma irradiation were 23% and 19.5% at wound inoculation and spray inoculation, respectively. On wound-inoculation, the control value of NaDCC only was 89%, and that of NaDCC convergent with 200 Gy gamma irradiation was 32%. On sprayinoculation, the highest control value was NaDCC at 50%, and that of NaDCC convergent with gamma irradiation was 24%.
Full Text Available Glutaredoxins (GRXs belong to the antioxidants involved in the cellular stress responses. In spite of the identification 48 GRX genes in rice genomes, the biological functions of most of them remain unknown. Especially, the biological roles of members of GRX family in disease resistance are still lacking. Our proteomic analysis found that OsGRX20 increased by 2.7-fold after infection by bacterial blight. In this study, we isolated and characterized the full-length nucleotide sequences of the rice OsGRX20 gene, which encodes a GRX family protein with CPFC active site of CPYC-type class. OsGRX20 protein was localized in nucleus and cytosol, and its transcripts were expressed predominantly in leaves. Several stress- and hormone-related motifs putatively acting as regulatory elements were found in the OsGRX20 promoter. Real-time quantitative PCR analysis indicated that OsGRX20 was expressed at a significantly higher level in leaves of a resistant or tolerant rice genotype, Yongjing 50A, than in a sensitive genotype, Xiushui 11, exposed to bacterial blight, methyl viologen, heat, and cold. Its expression could be induced by salt, PEG-6000, 2,4-D, salicylic acid, jasmonic acid, and abscisic acid treatments in Yongjing 50A. Overexpression of OsGRX20 in rice Xiushui 11 significantly enhanced its resistance to bacterial blight attack, and tolerance to methyl viologen and salt stresses. In contrast, interference of OsGRX20 in Yongjing 50A led to increased susceptibility to bacterial blight, methyl viologen and salt stresses. OsGRX20 restrained accumulation of superoxide radicals in aerial tissue during methyl viologen treatment. Consistently, alterations in OsGRX20 expression affect the ascorbate/dehydroascorbate ratio and the abundance of transcripts encoding four reactive oxygen species scavenging enzymes after methyl viologen-induced stress. Our results demonstrate that OsGRX20 functioned as a positive regulator in rice tolerance to multiple stresses
Šebela, David; Quiňones, C.; Cruz, C.; Ona, I.; Olejníčková, Julie; Jagadish, K. S. V.
Roč. 59, č. 1 (2018), s. 30-43 ISSN 0032-0781 R&D Projects: GA MŠk(CZ) LO1415 EU Projects: European Commission(XE) 284443 - EPPN Institutional support: RVO:86652079 Keywords : marker-assisted selection * oryza-sativa l. * water- stress * magnaporthe-grisea * disease resistance * photosynthetic efficiency * spectral reflectance * carotenoid content * eucalyptus leaves * diurnal changes * Bacterial blight * Chlorophyll fluorescence * Drought stress * Reflectance * Rice bast Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 4.760, year: 2016
Song, Alin; Xue, Gaofeng; Cui, Peiyuan; Fan, Fenliang; Liu, Hongfang; Yin, Chang; Sun, Wanchun; Liang, Yongchao
Here we report for the first time that bacterial blight of rice can be alleviated by silicon (Si) added. In both inoculated and uninoculated plants, shoot dry weight was significantly higher in the +Si plants than in the −Si plants. A soil-cultured trial showed that disease severity was 24.3% lower in the Si-amended plants than in the non-Si-amended plants. Plants that were switched from −Si to +Si nutrient solution and simultaneously inoculated with Xoo also exhibited the same high resistance to bacterial blight as the plants that were treated continuously with Si, with control efficiencies of 52.8 and 62.9%, respectively. Moreover, total concentrations of soluble phenolics and lignin in rice leaves were significantly higher in the +Si plants than in the −Si plants. Polyphenoloxidase (PPO) and phenylalanine ammonia-lyase (PAL) activities in rice leaves were observed to be higher in the +Si plants than in the −Si plants. The expression levels of Os03g0109600, Prla, Rcht2 and Lox2osPil, were also higher in +Si plants than in −Si plants post-inoculation during the experimental time. Addition of Si resulted in increased Pal transcription, and inhibited CatA and Os03g0126000 expression in the earlier and later stages of bacterial inoculation, respectively. PMID:27091552
Resistance to common bacterial blight in common bean is a complex trait that is quantitatively inherited. We examined the interaction between two independent QTL, SAP6 and SU91, which condition resistance to CBB.The QTL were studied in a pinto bean F2 population a cross between Othello (sap6 sap6 //...
González, Ana J.; Landeras, Elena; Mendoza, M. Carmen
Ribotyping was evaluated as a method to differentiate between Pseudomonas syringae pv. phaseolicola and pv. syringae strains causing bacterial brown spot and halo blight diseases in Phaseolus vulgaris L. Ribotyping, with restriction enzymes BglI and SalI and using the Escherichia coli rrnB operon as the probe, differentiated 11 and 14 ribotypes, respectively, and a combination of data from both procedures yielded 19 combined ribotypes. Cluster analysis of the combined ribotypes differentiated the pathovars phaseolicola and syringae, as well as different clonal lineages within these pathovars. The potential of ribotyping to screen for correlations between lineages and factors such as geographical region and/or bean varieties is also reported. PMID:10653764
Bruno Sérgio Vieira; Olinto Liparini Pereira; Márcio Luiz Batista; Robert Weingart Barreto
Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.Glomerella cingulata foi encontrado causando severa queima-foliar em Talauma ovata, uma espécie arbórea comum em florestas úmidas tropicais do Sudeste do Brasil. A doença e o patógeno foram descr...
Mridha, M.A.U.; Rehman, M.M.
Catharanthus roseus (L.).G. Don, a highly valued medicinal plant suffers from a serious disease. A survey on the symptom and severity of the leaf blight of C. roseus was performed in the nurseries of the Institute of Forestry and Environmental Sciences (IFESCU), Bangladesh Council of Industrial Research (BCSIR) and Bangladesh Forest Research Institute (BFRI), Bangladesh. An observation was also made in the avenues and garden of King Saud University (KSU), Kingdom of Saudi Arabia. No disease was recorded in KSU, but severe infections were found in all the locations surveyed in Bangladesh. The highest infection percentage and the highest disease index were found in BCSIR nursery followed by BFRI and the lowest was recorded in IFESCU nursery. Macrophomina phaseolina (Tassi) Goid was isolated and it was proved to be pathogenic. This is the first report of leaf blight of C. roseus caused by M. phaseolina. Azadirachta indica, Ocimum sanctum Vitex negundo, Mucuna pruriens, Calotropis procera, Terminalia arjuna, Allium sativum, Zingiber officinalis and Allium cepa were used as biopesticides. Out of the nine plant species screened, T. arjuna showed the highest (58.37%) inhibition percentage which was followed by A. indica (55.72%) and the lowest (27.4%) inhibition percentage were obtained with V. negundo whereas the rest of the plant extracts showed more or less same inhibitory effect. (author)
Full Text Available Interaction between rice ( L. and its bacterial blight (BB pathogen pv. ( is the model system between monocot plants and their bacterial pathogens. To understand the genome-wide interactions between and rice resulting from a broad-spectrum hypersensitive reaction (BSHR mediated by a new rice resistance ( gene, , comparative dynamic transcriptomic profiles in the incompatible and compatible interactions were investigated using three related rice lines and a highly virulent isolate, PXO99. Large numbers of rice and differentially expressed genes (DEGs were identified in comparisons between the incompatible interactions and compatible ones, suggesting the gene network consisted of 27 genes in four groups of distinct functions involving leading to BSHR of rice in the sequential events from the × interaction → signal recognition and transduction → protein modification → programmed cell death. Correspondingly, several groups of genes expressed or upregulated specifically in the incompatible interaction were those for type III secretion system (T3SS and type III secretion effectors (T3SEs. Combined evidence suggests LOC_Os11g37759, one of a two-member CC-NBS-LRR gene family on rice chromosome 11, as the most likely candidate for in rice and two genes, and involved in T3SS of , as the most likely candidate genes for the corresponding in . Our transcriptome data and identified rice and DEGs provided a valuable source of information for future investigations on the –rice interactions.
Argueso, Cristiana T.; Pereira, Andy; Vera Cruz, Casiana; Verdier, Valerie
Plant disease is a major challenge to agriculture worldwide, and it is exacerbated by abiotic environmental factors. During some plant-pathogen interactions, heat stress allows pathogens to overcome host resistance, a phenomenon which could severely impact crop productivity considering the global warming trends associated with climate change. Despite the importance of this phenomenon, little is known about the underlying molecular mechanisms. To better understand host plant responses during simultaneous heat and pathogen stress, we conducted a transcriptomics experiment for rice plants (cultivar IRBB61) containing Xa7, a bacterial blight disease resistance (R) gene, that were infected with Xanthomonas oryzae, the bacterial blight pathogen of rice, during high temperature stress. Xa7-mediated resistance is unusual relative to resistance mediated by other R genes in that it functions better at high temperatures. Using RNA-Seq technology, we identified 8,499 differentially expressed genes as temperature responsive in rice cultivar IRBB61 experiencing susceptible and resistant interactions across three time points. Notably, genes in the plant hormone abscisic acid biosynthesis and response pathways were up-regulated by high temperature in both mock-treated plants and plants experiencing a susceptible interaction and were suppressed by high temperature in plants exhibiting Xa7-mediated resistance. Genes responsive to salicylic acid, an important plant hormone for disease resistance, were down-regulated by high temperature during both the susceptible and resistant interactions, suggesting that enhanced Xa7-mediated resistance at high temperature is not dependent on salicylic acid signaling. A DNA sequence motif similar to known abscisic acid-responsive cis-regulatory elements was identified in the promoter region upstream of genes up-regulated in susceptible but down-regulated in resistant interactions. The results of our study suggest that the plant hormone abscisic
Stephen P Cohen
Full Text Available Plant disease is a major challenge to agriculture worldwide, and it is exacerbated by abiotic environmental factors. During some plant-pathogen interactions, heat stress allows pathogens to overcome host resistance, a phenomenon which could severely impact crop productivity considering the global warming trends associated with climate change. Despite the importance of this phenomenon, little is known about the underlying molecular mechanisms. To better understand host plant responses during simultaneous heat and pathogen stress, we conducted a transcriptomics experiment for rice plants (cultivar IRBB61 containing Xa7, a bacterial blight disease resistance (R gene, that were infected with Xanthomonas oryzae, the bacterial blight pathogen of rice, during high temperature stress. Xa7-mediated resistance is unusual relative to resistance mediated by other R genes in that it functions better at high temperatures. Using RNA-Seq technology, we identified 8,499 differentially expressed genes as temperature responsive in rice cultivar IRBB61 experiencing susceptible and resistant interactions across three time points. Notably, genes in the plant hormone abscisic acid biosynthesis and response pathways were up-regulated by high temperature in both mock-treated plants and plants experiencing a susceptible interaction and were suppressed by high temperature in plants exhibiting Xa7-mediated resistance. Genes responsive to salicylic acid, an important plant hormone for disease resistance, were down-regulated by high temperature during both the susceptible and resistant interactions, suggesting that enhanced Xa7-mediated resistance at high temperature is not dependent on salicylic acid signaling. A DNA sequence motif similar to known abscisic acid-responsive cis-regulatory elements was identified in the promoter region upstream of genes up-regulated in susceptible but down-regulated in resistant interactions. The results of our study suggest that the plant
Cohen, Stephen P; Liu, Hongxia; Argueso, Cristiana T; Pereira, Andy; Vera Cruz, Casiana; Verdier, Valerie; Leach, Jan E
Plant disease is a major challenge to agriculture worldwide, and it is exacerbated by abiotic environmental factors. During some plant-pathogen interactions, heat stress allows pathogens to overcome host resistance, a phenomenon which could severely impact crop productivity considering the global warming trends associated with climate change. Despite the importance of this phenomenon, little is known about the underlying molecular mechanisms. To better understand host plant responses during simultaneous heat and pathogen stress, we conducted a transcriptomics experiment for rice plants (cultivar IRBB61) containing Xa7, a bacterial blight disease resistance (R) gene, that were infected with Xanthomonas oryzae, the bacterial blight pathogen of rice, during high temperature stress. Xa7-mediated resistance is unusual relative to resistance mediated by other R genes in that it functions better at high temperatures. Using RNA-Seq technology, we identified 8,499 differentially expressed genes as temperature responsive in rice cultivar IRBB61 experiencing susceptible and resistant interactions across three time points. Notably, genes in the plant hormone abscisic acid biosynthesis and response pathways were up-regulated by high temperature in both mock-treated plants and plants experiencing a susceptible interaction and were suppressed by high temperature in plants exhibiting Xa7-mediated resistance. Genes responsive to salicylic acid, an important plant hormone for disease resistance, were down-regulated by high temperature during both the susceptible and resistant interactions, suggesting that enhanced Xa7-mediated resistance at high temperature is not dependent on salicylic acid signaling. A DNA sequence motif similar to known abscisic acid-responsive cis-regulatory elements was identified in the promoter region upstream of genes up-regulated in susceptible but down-regulated in resistant interactions. The results of our study suggest that the plant hormone abscisic
Full Text Available Many rice spotted-leaf (spl mutants are ideal sources for understanding the mechanisms involved in blast resistance, bacterial blight resistance and programmed cell death in plants. The genetic controls of 50 spotted-leaf mutants in rice have been characterized and a few spotted-leaf genes have been isolated as well. This article reviews the origin, genetic modes, isolation and characterization of spotted-leaf genes responsible for their phenotypes, and their resistance responses to main rice diseases.
Bruno Sérgio Vieira
Full Text Available Glomerella cingulata was found causing severe leaf blight on Talauma ovata, a common tree species in the Atlantic tropical rain forest floodplains of Southern Brazil. The disease and pathogen are described and illustrated and patogenicity is also demonstrated. This is the first report of this disease.Glomerella cingulata foi encontrado causando severa queima-foliar em Talauma ovata, uma espécie arbórea comum em florestas úmidas tropicais do Sudeste do Brasil. A doença e o patógeno foram descritos e ilustrados, e sua patogenicidade também foi demonstrada. Esse é o primeiro relato dessa doença.
Dai, Yi; Duan, Yamei; Liu, Huiping; Chi, Dawn; Cao, Wenguang; Xue, Allen; Gao, Yong; Fedak, George; Chen, Jianmin
Fusarium head blight (FHB), leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host) Dewey (2 n = 2 x = 14, EE) is an excellent source of disease resistance genes. Two new Triticum-Secale-Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2 n = 6 x = 42, AABBRR) and a hexaploid Triticum trititrigia (2 n = 6 x = 42, AABBEE), were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R), and four pairs of E-chromosomes (1E, 2E, 3E, and 5E) for a total chromosome number of 2 n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2 n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62) display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.
Pradhan, Sharat Kumar; Nayak, Deepak Kumar; Mohanty, Soumya; Behera, Lambodar; Barik, Saumya Ranjan; Pandit, Elssa; Lenka, Srikanta; Anandan, Annamalai
Jalmagna is a popular deepwater rice variety with farmers of India because of its good yield under waterlogged condition. However, the variety is highly susceptible to bacterial blight (BB) disease. The development of resistant cultivars has been the most effective and economical strategy to control the disease under deepwater situation. Three resistance genes (xa5 + xa13 + Xa21) were transferred from Swarna BB pyramid line, using a marker-assisted backcrossing (MAB) breeding strategy, into the BB-susceptible elite deepwater cultivar, Jalmagna. Molecular marker integrated backcross breeding program has been employed to transfer three major BB resistance genes (Xa21, xa13 and xa5) into Jalmagna variety. During backcross generations, markers closely linked to the three genes were used to select plants possessing these resistance genes and markers polymorphic between donor and recurrent parent were used to select plants that have maximum contribution from the recurrent parent genome. A selected BC3F1 plant was selfed to generate homozygous BC3F2 plants with different combinations of BB resistance genes. The three-gene pyramid and two gene pyramid lines exhibited high levels of resistance against the BB pathogen. Under conditions of BB infection, the three-gene pyramided lines exhibited a significant yield advantage over Jalmagna. The selected pyramided lines showed all agro-morphologic traits of Jalmagna without compromising the yield. The three major BB resistance genes pyramided lines exhibited high level of resistance and are expected to provide durable resistance under deep water situation where control through chemicals is less effective. High similarity in agro-morphologic traits and absence of antagonistic effects for yield and other characters were observed in the best pyramided lines.
Lev G Nemchinov
Full Text Available Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L. Little is known about host-pathogen interactions and host defense mechanisms. Here, individual resistant and susceptible plants were selected from cultivars Maverick and ZG9830 and used for transcript profiling at 24 and 72 hours after inoculation (hai with the isolate PssALF3. Bioinformatic analysis revealed a number of differentially expressed genes (DEGs in resistant and susceptible genotypes. Although resistant plants from each cultivar produced a hypersensitive response, transcriptome analyses indicated that they respond differently at the molecular level. The number of DEGs was higher in resistant plants of ZG9830 at 24 hai than in Maverick, suggesting that ZG9830 plants had a more rapid effector triggered immune response. Unique up-regulated genes in resistant ZG9830 plants included genes encoding putative nematode resistance HSPRO2-like proteins, orthologs for the rice Xa21 and soybean Rpg1-b resistance genes, and TIR-containing R genes lacking both NBS and LRR domains. The suite of R genes up-regulated in resistant Maverick plants had an over-representation of R genes in the CC-NBS-LRR family including two genes for atypical CCR domains and a putative ortholog of the Arabidopsis RPM1 gene. Resistance in both cultivars appears to be mediated primarily by WRKY family transcription factors and expression of genes involved in protein phosphorylation, regulation of transcription, defense response including synthesis of isoflavonoids, and oxidation-reduction processes. These results will further the identification of mechanisms involved in resistance to facilitate selection of parent populations and development of commercial varieties.
Ellur, Ranjith K; Khanna, Apurva; Yadav, Ashutosh; Pathania, Sandeep; Rajashekara, H; Singh, Vikas K; Gopala Krishnan, S; Bhowmick, Prolay K; Nagarajan, M; Vinod, K K; Prakash, G; Mondal, Kalyan K; Singh, Nagendra K; Vinod Prabhu, K; Singh, Ashok K
Marker assisted backcross breeding was employed to incorporate the blast resistance genes, Pi2 and Pi54 and bacterial blight (BB) resistance genes xa13 and Xa21 into the genetic background of Pusa Basmati 1121 (PB1121) and Pusa Basmati 6. Foreground selection for target gene(s) was followed by arduous phenotypic and background selection which fast-tracked the recovery of recurrent parent genome (RPG) to an extent of 95.8% in one of the near-isogenic lines (NILs) namely, Pusa 1728-23-33-31-56, which also showed high degree of resemblance to recurrent parent, PB6 in phenotype. The phenotypic selection prior to background selection provided an additional opportunity for identifying the novel recombinants viz., Pusa 1884-9-12-14 and Pusa 1884-3-9-175, superior to parental lines in terms of early maturity, higher yield and improved quality parameters. There was no significant difference between the RPG recovery estimated based on SSR or SNP markers, however, the panel of SNPs markers was considered as the better choice for background selection as it provided better genome coverage and included SNPs in the genic regions. Multi-location evaluation of NILs depicted their stable and high mean performance in comparison to the respective recurrent parents. The Pi2+Pi54 carrying NILs were effective in combating a pan-India panel of Magnaporthe oryzae isolates with high level of field resistance in northern, eastern and southern parts of India. Alongside, the PB1121-NILs and PB6-NILs carrying BB resistance genes xa13+Xa21 were resistant against Xanthomonas oryzae pv. oryzae races of north-western, southern and eastern parts of the country. Three of NILs developed in this study, have been promoted to final stage of testing during the Kharif 2015 in the Indian National Basmati Trial. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Nemchinov, Lev G; Shao, Jonathan; Lee, Maya N; Postnikova, Olga A; Samac, Deborah A
Bacterial stem blight caused by Pseudomonas syringae pv. syringae is a common disease of alfalfa (Medicago sativa L). Little is known about host-pathogen interactions and host defense mechanisms. Here, individual resistant and susceptible plants were selected from cultivars Maverick and ZG9830 and used for transcript profiling at 24 and 72 hours after inoculation (hai) with the isolate PssALF3. Bioinformatic analysis revealed a number of differentially expressed genes (DEGs) in resistant and susceptible genotypes. Although resistant plants from each cultivar produced a hypersensitive response, transcriptome analyses indicated that they respond differently at the molecular level. The number of DEGs was higher in resistant plants of ZG9830 at 24 hai than in Maverick, suggesting that ZG9830 plants had a more rapid effector triggered immune response. Unique up-regulated genes in resistant ZG9830 plants included genes encoding putative nematode resistance HSPRO2-like proteins, orthologs for the rice Xa21 and soybean Rpg1-b resistance genes, and TIR-containing R genes lacking both NBS and LRR domains. The suite of R genes up-regulated in resistant Maverick plants had an over-representation of R genes in the CC-NBS-LRR family including two genes for atypical CCR domains and a putative ortholog of the Arabidopsis RPM1 gene. Resistance in both cultivars appears to be mediated primarily by WRKY family transcription factors and expression of genes involved in protein phosphorylation, regulation of transcription, defense response including synthesis of isoflavonoids, and oxidation-reduction processes. These results will further the identification of mechanisms involved in resistance to facilitate selection of parent populations and development of commercial varieties.
Phage induction by ultraviolet radiation (UV) and mitomycin C (MMC) in some lysogenic strains of Pseudomonas mori, the pathogen of bacterial blight of mulberry, was examined. Among 5 strains tested, in the strains S 6804 and S 6805, phage was induced by both UV and MMC, and in the strain M 5, only by MMC. In the strains S 6807 and S 6808, it was not induced by both these inducers. The rate of phage production in the strain 6805 was highest when it was exposed to UV (15 W UV lamp, 40 cm) for 5 seconds, by which about 90% of the bacteria were killed, and decreased rapidly by further extending the exposure time. The bacteria suspended in 0.02 M magnesium solution were more sensitive in responding to UV than those suspended in nutrient broth, but after the UV treatment, nutrient broth was more favorable than magnesium solution for phage production. The MMC added to nutrient broth induced phage production at the concentration from 0.5 to 5 μg/ml. The strains induced by either UV or MMC their temperate phages after about 3 hours of latent period. The phage induction by UV was almost completely suppressed by 40 minute exposure to fluorescent light (a 15 W fluorescent lamp, 10 cm) or by 5 minute exposure to sunlight, given within 45 minutes after the UV treatment, i.e. within 1/4 of the latent period. Thus, the photoreversion of the UV effect on phage induction was observed in Ps. mori as well as in Ps. pyocyanea and E. coli. (Kaihara, S.)
Full Text Available Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight (BB diseases, the two most prevalent diseases jeopardizing rice production. Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food. An incomplete diallele design resulted in 25 crosses between five blast and five BB resistant germplasm accessions. Only one pair of parents, DH146 × TM487, showed polymorphism for all the markers to identify one blast resistance gene Pi25 and three BB resistance genes, Xa21, xa13 and xa5, thus it was used in the marker-assisted selection (MAS. F2 individuals of DH146 × TM487 were genotyped using flanking markers of RM3330 and sequence tagged site (STS marker SA7 for Pi25. The resistant F2 plants with Pi25 were used for pyramiding BB resistance genes Xa21, xa13 and xa5 identified by the markers pTA248, RM264 and RM153, respectively in subsequent generations. Finally, after selection for agronomic traits and restoration ability among 12 pyramided lines, we acquired an elite restorer line, R8012 including all four target genes (Pi25+Xa21+xa13+xa5. Hybrid Zhong 9A/R8012 derived from the selected line showed stronger resistance to blast and BB, and higher grain yield than the commercial checks uniformally in experimental plots, 2007 state-wide yield trial and 2008 nation-wide yield trial. This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes. The resultant restoring line and its hybrid would play an important role in securing rice production in China.
João Américo Wordell Filho
Full Text Available O presente trabalho estudou o efeito da adubação química e orgânica, fungicidas, fertilizantes foliares e extratos vegetais sobre a severidade da mancha acinzentada causada por Botrytis squamosa e a qualidade de mudas de cebola. Para tanto, realizou-se um experimento na Epagri/Estação Experimental de Ituporanga, SC, no período de maio a julho de 2005. Em um delineamento experimental de blocos casualizados com quatro repetições, em esquema de parcela sub-dividida, testou-se os seguintes tratamentos (Fator A: a testemunha; b fungicida ciprodinil (75 g i.a./100 L; c fosfito de potássio (00-30-20, 250 mL/100 L; d fertilizante foliar (03-00-16, 400 mL/100 L; e calda bordalesa (0,3%; f calda bordalesa/fosfito de potássio; g extrato da alga Ulva fasciata (0,2%, peso seco: volume; h extrato de cavalinha Equisetum arwense (0,26%; i extrato de Urtiga dióica (0,47%. Os canteiros foram conduzidos com adubação química ou orgânica (Fator B. A área foliar necrosada foi avaliada semanalmente e usada para calcular a área abaixo da curva de progresso da doença (AACPD. O tipo de fertilização não afetou o desenvolvimento da mancha acinzentada, porém a adubação química aumentou o comprimento e o diâmetro do pseudocaule das mudas. Os tratamentos ciprodinil, fosfito de potássio, fertilizante foliar (03-00-16, calda bordalesa e fosfito combinado com calda bordalesa, reduziram significativamente a doença, enquanto que os extratos não foram eficazes.This work studied the effect of mineral and organic fertilization, fungicides, foliar fertilizers and plant extracts on the severity of onion leaf blight caused by Botrytis squamosa and onseedling quality. Field experiment was carried out at Epagri's experimental station in Ituporanga-SC from May to July 2005. In a split-plot design with four replicates the following treatments (factor A were tested: a control; b fungicide ciprodinil (75 g a.i./100 L; c potassium fosfite (00-30-20, 250 mL./100 L
Full Text Available Fusarium head blight (FHB, leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host Dewey (2n = 2x = 14, EE is an excellent source of disease resistance genes. Two new Triticum–Secale–Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2n = 6x = 42, AABBRR and a hexaploid Triticum trititrigia (2n = 6x = 42, AABBEE, were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R, and four pairs of E-chromosomes (1E, 2E, 3E, and 5E for a total chromosome number of 2n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62 display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.
Full Text Available Bacterial leaf symbiosis is a unique and intimate interaction between bacteria and flowering plants, in which endosymbionts are organized in specialized leaf structures. Previously, bacterial leaf symbiosis has been described as a cyclic and obligate interaction in which the endosymbionts are vertically transmitted between plant generations and lack autonomous growth. Theoretically this allows for co-speciation between leaf nodulated plants and their endosymbionts. We sequenced the nodulated Burkholderia endosymbionts of 54 plant species from known leaf nodulated angiosperm genera, i.e. Ardisia, Pavetta, Psychotria and Sericanthe. Phylogenetic reconstruction of bacterial leaf symbionts and closely related free-living bacteria indicates the occurrence of multiple horizontal transfers of bacteria from the environment to leaf nodulated plant species. This rejects the hypothesis of a long co-speciation process between the bacterial endosymbionts and their host plants. Our results indicate a recent evolutionary process towards a stable and host specific interaction confirming the proposed maternal transmission mode of the endosymbionts through the seeds. Divergence estimates provide evidence for a relatively recent origin of bacterial leaf symbiosis, dating back to the Miocene (5-23 Mya. This geological epoch was characterized by cool and arid conditions, which may have triggered the origin of bacterial leaf symbiosis.
Abhilash Kumar, V; Balachiranjeevi, C H; Bhaskar Naik, S; Rambabu, R; Rekha, G; Harika, G; Hajira, S K; Pranathi, K; Anila, M; Kousik, M; Vijay Kumar, S; Yugander, A; Aruna, J; Dilip Kumar, T; Vijaya Sudhakara Rao, K; Hari Prasad, A S; Madhav, M S; Laha, G S; Balachandran, S M; Prasad, M S; Viraktamath, B C; Ravindra Babu, V; Sundaram, R M
RPHR-1005, the stable restorer line of the popular medium slender (MS) grain type rice hybrid, DRRH-3 was improved in this study for resistance against bacterial blight (BB) and blast diseases through marker-assisted backcross breeding (MABB). In this study, four major resistance genes (i.e., Xa21 and Xa33 for BB resistance and Pi2 and Pi54 for blast resistance) have been transferred to RPHR-1005 using RPBio Patho-1 (possessing Xa21 + Pi2), RPBio Patho-2 (possessing Xa21 + Pi54) and FBR1-15EM (possessing Xa33) as the donors. Foreground selection was carried out using PCR-based molecular markers specific for the target resistance genes and the major fertility restorer genes, Rf3 and Rf4, while background selection was carried out using a set of parental polymorphic rice SSR markers and backcrossing was continued uptoBC2 generation. At BC2F2, plants possessing the gene combination- Xa21 + Pi2, Xa21 + Pi54 and Xa33 in homozygous condition and with >92% recovery of the recurrent parent genome (RPG) were identified and intercrossed to combine all the four resistance genes. Twenty-two homozygous, pyramid lines of RPHR-1005 comprising of three single-gene containing lines, six 2-gene containing lines, eight 3-gene containing lines, and five 4-gene containing lines were identified among the double intercross lines at F3 generation (DICF3). They were then evaluated for their resistance against BB and blast, fertility restoration ability and for key agro-morphological traits. While single gene containing lines were resistant to either BB or blast, the 2-gene, 3-gene, and 4-gene pyramid lines showed good level of resistance against both and/or either of the two diseases. Most of the 2-gene, 3-gene, and 4-gene containing pyramid lines showed yield levels and other key agro-morphological and grain quality traits comparable to the original recurrent parent and showed complete fertility restoration ability, with a few showing higher yield as compared to RPHR-1005. Further, the
Yoodee, Sunisa; Kobayashi, Yohko; Songnuan, Wisuwat; Boonchird, Chuenchit; Thitamadee, Siripong; Kobayashi, Issei; Narangajavana, Jarunya
Cassava bacterial blight (CBB) disease caused by Xanthomonas axonopodis pv. manihotis (Xam) is a severe disease in cassava worldwide. In addition to causing significant cassava yield loss, CBB disease has not been extensively studied, especially in terms of CBB resistance genes. The present research demonstrated the molecular mechanisms underlining the defense response during Xam infection in two cassava cultivars exhibiting different degrees of disease resistance, Huay Bong60 (HB60) and Hanatee (HN). Based on gene expression analysis, ten of twelve putative defense-related genes including, leucine-rich repeat receptor-like kinases (LRR-RLKs), resistance (R), WRKY and pathogenesis-related (PR) genes, were differentially expressed between these two cassava cultivars during Xam infection. The up-regulation of defense-related genes observed in HB60 may be the mechanism required for the reduction of disease severity in the resistant cultivar. Interestingly, priming with salicylic acid (SA) or methyl jasmonate (MeJA) for 24 h before Xam inoculation could enhance the defense response in both cassava cultivars. The disease severity was decreased 10% in the resistant cultivar (HB60) and was remarkably reduced 21% in the susceptible cultivar (HN) by SA/MeJA priming. Priming with Xam inoculation modulated cassava4.1_013417, cassava4.1_030866 and cassava4.1_020555 (highest similarity to MeWRKY59, MePR1 and AtPDF2.2, respectively) expression and led to enhanced resistance of the susceptible cultivar in the second infection. The putative cis-regulatory elements were predicted in an upstream region of these three defense-related genes. The different gene expression levels in these genes between the two cultivars were due to the differences in cis-regulatory elements in their promoter regions. Taken together, our study strongly suggested that the induction of defense-related genes correlated with defense resistance against Xam infection, and exogenous application of SA or Me
Full Text Available Basic domain-leucine zipper (bZIP transcription factor, one type of conserved gene family, plays an important role in plant development and stress responses. Although 77 MebZIPs have been genome-wide identified in cassava, their in vivo roles remain unknown. In this study, we analyzed the expression pattern and the function of two MebZIPs (MebZIP3 and MebZIP5 in response to pathogen infection. Gene expression analysis indicated that MebZIP3 and MebZIP5 were commonly regulated by flg22, Xanthomonas axonopodis pv. manihotis (Xam, salicylic acid (SA, and hydrogen peroxide (H2O2. Subcellular localization analysis showed that MebZIP3 and MebZIP5 are specifically located in cell nucleus. Through overexpression in tobacco, we found that MebZIP3 and MebZIP5 conferred improved disease resistance against cassava bacterial blight, with more callose depositions. On the contrary, MebZIP3- and MebZIP5-silenced plants by virus-induced gene silencing (VIGS showed disease sensitive phenotype, lower transcript levels of defense-related genes and less callose depositions. Taken together, this study highlights the positive role of MebZIP3 and MebZIP5 in disease resistance against cassava bacterial blight for further utilization in genetic improvement of cassava disease resistance.
Full Text Available Four hundred and sixty two strains of Trichoderma spp. were isolated from 23 soil samples in which groundnut (Arachis hypogaea L. and bambara groundnut (Vigna subterranea L. had been planted in Songkhla, Phattalung, Nakhon Si Thammarat, Narathiwat and Yala provinces. These fungi were tested against Rhizoctonia solani, a causal agent of leaf blight of bambara groundnut, using dual culture technique on PDA medium. Among 462 isolates tested, 226 isolates had an ability to overgrow R. solani completely. Further testing found 13 isolates having the ability to parasitize mycelia of R. solani. Among these isolates, ThB-1-54 produced a cellulolytic enzyme on congo-red agar. This isolate was later identified as T. harzianum Rifai. In the field test, applying biomass of the isolate ThB-1-54 cultured on ground mesocarp fiber of oil palm, the combination of the isolate ThB-1-54 on ground mesocarp fiber of oil palm and Bradyrhizobium sp. (strain NC 92, or fungicide (iprodione had no effect on disease severity, yield, or the amount of total nitrogen content in stems or seeds of bambara groundnut plant.
Full Text Available The phyllosphere supports a large and complex bacterial community that varies both across plant species and geographical locations. Phyllosphere bacteria can have important effects on plant health. The sweet chestnut (Castanea sativa Mill. is an economically important tree species affected worldwide by the fungal pathogens Cryphonectria parasitica and Phytophthora cinnamomi. We examined the culturable phyllosphere bacterial community of the sweet chestnut at two nearby locations in Central Spain in order to know its geographical variability and to explore its potential as source of biological control agents against these two pathogenic fungi. The bacterial diversity at strain level was high but it varied significantly between locations; however, phylotype richness and diversity were more comparable. The isolates were affiliated with the phyla Actinobacteria, Firmicutes and Proteobacteria. Most of them were members of recognized bacterial species, with a notable proportion of representative of the genera Dietzia and Lonsdalea, but a small fraction of the strains revealed the existence of several potential novel species or even genera. Antagonism tests showed the occurrence in the chestnut phyllosphere of bacterial strains potentially useful as biological control agents against the two pathogenic fungi, some of which belong to species never before described as fungal antagonists. Chestnut phyllosphere, therefore, contains a great diversity of culturable bacteria and may represent an untapped source of potential biocontrol agents against the fungi causing blight and ink diseases of this tree species.
Feb 8, 2018 ... IDENTIFICATION OF COMMON BEAN GENOTYPES WITH DUAL LEAF AND. POD RESISTANCE TO COMMON BACTERIAL BLIGHT DISEASE IN UGANDA. B.M.E. ALLADASSI, S.T. NKALUBO1, C. MUKANKUSI2, H.N. KAYAGA, P. GIBSON, R. EDEMA,. C.A. URREA3, J.D. KELLY4 and P.R. RUBAIHAYO.
Full Text Available Abstract Background Xanthomonas oryzae pv. oryzae (Xoo is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF type quorum sensing (QS system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc, suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 μM to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed
Alternaria blight of chickpea is caused by the fungal pathogen Alternaria alternata. The pathogen has wide host range, and affects all above ground parts of the plant. The disease occurs sporadically and occasionally could be economically important and causes significant damage. The pathogen can ...
Taniguchi, Shiduku; Hosokawa-Shinonaga, Yumi; Tamaoki, Daisuke; Yamada, Shoko; Akimitsu, Kazuya; Gomi, Kenji
Jasmonic acid (JA) is involved in the regulation of host immunity in plants. Recently, we demonstrated that JA signalling has an important role in resistance to rice bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) in rice. Here, we report that many volatile compounds accumulate in response to exogenous application of JA, including the monoterpene linalool. Expression of linalool synthase was up-regulated by JA. Vapour treatment with linalool induced resistance to Xoo, and transgenic rice plants overexpressing linalool synthase were more resistance to Xoo, presumably due to the up-regulation of defence-related genes in the absence of any treatment. JA-induced accumulation of linalool was regulated by OsJAZ8, a rice jasmonate ZIM-domain protein involving the JA signalling pathway at the transcriptional level, suggesting that linalool plays an important role in JA-induced resistance to Xoo in rice. © 2013 John Wiley & Sons Ltd.
Wu, Jing; Zhu, Jifeng; Wang, Lanfen; Wang, Shumin
Nucleotide-binding site and leucine-rich repeat (NBS-LRR) genes represent the largest and most important disease resistance genes in plants. The genome sequence of the common bean (Phaseolus vulgaris L.) provides valuable data for determining the genomic organization of NBS-LRR genes. However, data on the NBS-LRR genes in the common bean are limited. In total, 178 NBS-LRR-type genes and 145 partial genes (with or without a NBS) located on 11 common bean chromosomes were identified from genome sequences database. Furthermore, 30 NBS-LRR genes were classified into Toll/interleukin-1 receptor (TIR)-NBS-LRR (TNL) types, and 148 NBS-LRR genes were classified into coiled-coil (CC)-NBS-LRR (CNL) types. Moreover, the phylogenetic tree supported the division of these PvNBS genes into two obvious groups, TNL types and CNL types. We also built expression profiles of NBS genes in response to anthracnose and common bacterial blight using qRT-PCR. Finally, we detected nine disease resistance loci for anthracnose (ANT) and seven for common bacterial blight (CBB) using the developed NBS-SSR markers. Among these loci, NSSR24, NSSR73, and NSSR265 may be located at new regions for ANT resistance, while NSSR65 and NSSR260 may be located at new regions for CBB resistance. Furthermore, we validated NSSR24, NSSR65, NSSR73, NSSR260, and NSSR265 using a new natural population. Our results provide useful information regarding the function of the NBS-LRR proteins and will accelerate the functional genomics and evolutionary studies of NBS-LRR genes in food legumes. NBS-SSR markers represent a wide-reaching resource for molecular breeding in the common bean and other food legumes. Collectively, our results should be of broad interest to bean scientists and breeders. PMID:28848595
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.
Full Text Available The plant hormone abscisic acid (ABA is involved in a wide variety of plant processes, including the initiation of stress-adaptive responses to various environmental cues. Recently, ABA also emerged as a central factor in the regulation and integration of plant immune responses, although little is known about the underlying mechanisms. Aiming to advance our understanding of ABA-modulated disease resistance, we have analyzed the impact, dynamics and interrelationship of ABA and the classic defense hormone salicylic acid (SA during progression of rice infection by the leaf blight pathogen Xanthomonas oryzae pv. oryzae (Xoo. Consistent with ABA negatively regulating resistance to Xoo, we found that exogenously administered ABA renders rice hypersusceptible to infection, whereas chemical and genetic disruption of ABA biosynthesis and signaling, respectively, led to enhanced Xoo resistance. In addition, we found successful Xoo infection to be associated with extensive reprogramming of ABA biosynthesis and response genes, suggesting that ABA functions as a virulence factor for Xoo. Interestingly, several lines of evidence indicate that this immune-suppressive effect of ABA is due at least in part to suppression of SA-mediated defenses that normally serve to limit pathogen growth. Resistance induced by the ABA biosynthesis inhibitor fluridone, however, appears to operate in a SA-independent manner and is likely due to induction of non-specific physiological stress. Collectively, our findings favor a scenario whereby virulent Xoo hijacks the rice ABA machinery to cause disease and highlight the importance of ABA and its crosstalk with SA in shaping the outcome of rice-Xoo interactions.
Hurni, Severine; Scheuermann, Daniela; Krattinger, Simon G; Kessel, Bettina; Wicker, Thomas; Herren, Gerhard; Fitze, Mirjam N; Breen, James; Presterl, Thomas; Ouzunova, Milena; Keller, Beat
Northern corn leaf blight (NCLB) caused by the hemibiotrophic fungus Exserohilum turcicum is an important foliar disease of maize that is mainly controlled by growing resistant maize cultivars. The Htn1 locus confers quantitative and partial NCLB resistance by delaying the onset of lesion formation. Htn1 represents an important source of genetic resistance that was originally introduced from a Mexican landrace into modern maize breeding lines in the 1970s. Using a high-resolution map-based cloning approach, we delimited Htn1 to a 131.7-kb physical interval on chromosome 8 that contained three candidate genes encoding two wall-associated receptor-like kinases (ZmWAK-RLK1 and ZmWAK-RLK2) and one wall-associated receptor-like protein (ZmWAK-RLP1). TILLING (targeting induced local lesions in genomes) mutants in ZmWAK-RLK1 were more susceptible to NCLB than wild-type plants, both in greenhouse experiments and in the field. ZmWAK-RLK1 contains a nonarginine-aspartate (non-RD) kinase domain, typically found in plant innate immune receptors. Sequence comparison showed that the extracellular domain of ZmWAK-RLK1 is highly diverse between different maize genotypes. Furthermore, an alternative splice variant resulting in a truncated protein was present at higher frequency in the susceptible parents of the mapping populations compared with in the resistant parents. Hence, the quantitative Htn1 disease resistance in maize is encoded by an unusual innate immune receptor with an extracellular wall-associated kinase domain. These results further highlight the importance of this protein family in resistance to adapted pathogens.
Gerard C. Adams; Mursel Catall; James Walla; Ann B. Gould
Bacterial leaf scorch (BLS) of shade trees is the common name for a disease caused by Xylella fastidiosa, a xylem-inhabiting bacterium that has fastidious nutritional requirements and is difficult to culture or verify by culturing. Forest trees including oak, sycamore, elm, planetree, sweetgum, mulberry and maple are species susceptible to ...
Ephantus J Muturi
Full Text Available Lentic freshwater systems including those inhabited by aquatic stages of mosquitoes derive most of their carbon inputs from terrestrial organic matter mainly leaf litter. The leaf litter is colonized by microbial communities that provide the resource base for mosquito larvae. While the microbial biomass associated with different leaf species in container aquatic habitats is well documented, the taxonomic composition of these microbes and their response to common environmental stressors is poorly understood. We used indoor aquatic microcosms to determine the abundances of major taxonomic groups of bacteria in leaf litters from seven plant species and their responses to low concentrations of four pesticides with different modes of action on the target organisms; permethrin, malathion, atrazine and glyphosate. We tested the hypotheses that leaf species support different quantities of major taxonomic groups of bacteria and that exposure to pesticides at environmentally relevant concentrations alters bacterial abundance and community structure in mosquito larval habitats. We found support for both hypotheses suggesting that leaf litter identity and chemical contamination may alter the quality and quantity of mosquito food base (microbial communities in larval habitats. The effect of pesticides on microbial communities varied significantly among leaf types, suggesting that the impact of pesticides on natural microbial communities may be highly complex and difficult to predict. Collectively, these findings demonstrate the potential for detritus composition within mosquito larval habitats and exposure to pesticides to influence the quality of mosquito larval habitats.
May 12, 1993 ... RxR bean lines to common bacterial blight. Thé F, were advanced to F; and in each cross over 250 F2 plants were used to evaluate for the number of genes controÜing résistance using Mendelian genetics and. Staniﬁeld 's formula. The plants were inoculated by razor blade method on the leaves and by ...
Hur, Yeon-Jae; Cho, Jun-Hyeon; Park, Hyun-Su; Noh, Tae-Hwan; Park, Dong-Soo; Lee, Ji Yun; Sohn, Young-Bo; Shin, Dongjin; Song, You Chun; Kwon, Young-Up; Lee, Jong-Hee
We fine mapped the Xa4 locus and developed a pyramided rice line containing Xa3 and Xa4 R - alleles and a cold-tolerance QTL. This line will be valuable in rice breeding. Bacterial blight (BB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a destructive disease of cultivated rice. Pyramiding BB resistance genes is an essential approach for increasing the resistance level of rice varieties. We selected an advanced backcross recombinant inbred line 132 (ABL132) from the BC3F7 population derived from a cross between cultivars Junam and IR72 by K3a inoculation and constructed the mapping population (BC4F6) to locate the Xa4 locus. The Xa4 locus was found to be delimited within a 60-kb interval between InDel markers InDel1 and InDel2 and tightly linked with the Xa3 gene on chromosome 11. After cold (4 °C) treatment, ABL132 with introgressions of IR72 in chromosome 11 showed lower survival rate, chlorophyll content, and relative water content compared to Junam. Genetic analysis showed that the cold stress-related quantitative trait locus (QTL) qCT11 was located in a 1.3-Mb interval close to the Xa4 locus. One line, ABL132-36, containing the Xa3 resistance allele from Junam, the Xa4 resistance allele from IR72, and the cold-tolerance QTL from Junam (qCT11), was developed from a BC4F6 population of 250 plants. This is the first report on the pyramiding of Xa3 and Xa4 genes with a cold-tolerance QTL. This region could provide a potential tool for improving resistance against BB and low-temperature stress in rice-breeding programs.
Influence of agronomic conditions on the efficacy of different fungicides applied to wheat at heading: effect on flag leaf senescence, Fusarium head blight attack, grain yield and deoxynivalenol contamination
Full Text Available A series of field experiments has been conducted in North West Italy over a period of 3 years to evaluate the effect of fungicide applications on common wheat yield and safety, combined with different agronomic conditions (high: a susceptible variety to FHB planted in an untilled field; low: a medium tolerant variety to FHB planted in a ploughed field for Fusarium head blight (FHB infection risk. A azole mixture (prochloraz + epoxiconazole, applied at heading, was compared in each year and for each agronomic condition with a triazole with high activity against F. graminearum and F. culmorum (metconazole, a strobilurin-azole mixture with elevated action to control leaf diseases and delay leaf senescence (azoxystrobin + prochloraz and an untreated control. The following parameters were analyzed: flag leaf greenness, grain yield, test weight, thousand kernel weight (TKW, FHB incidence and severity and deoxynivalenol (DON contamination. The results of this research, conducted over three years with different meteorological conditions, underline the important link between fungicide efficacy and environmental and agronomic conditions that can influence fungal disease pressure. The fungicide effect on the control of FHB and the increase in flag leaf longevity and grain yield were greater with an increase in the disease pressure. On the other hand, the DON contamination was reduced by the fungicide to a greater extent in the low risk agronomic and environmental conditions compared to the high risk ones. Prochloraz + epoxiconazole showed a lower efficacy in reducing DON contamination compared to metconazole, particularly in the higher FHB pressure conditions. No significant differences were observed between the azole mixture and the strobilurin-azole mixture for flag leaf greenness, grain yield, test weight or TKW. This study provides useful information that can be used to evaluate, in naturally-infected field conditions, the effect of a fungicide
Alessandra Keiko Nakasone Ishida
Full Text Available Avaliou-se o potencial de rizobactérias na indução de resistência do algodoeiro à Xanthomonas axonopodis pv. malvacearum. Após o isolamento das rizobactérias, foram selecionados os isolados capazes de reduzir os sintomas da mancha angular bacteriana em casa de vegetação, os quais foram aplicados espacialmente separados do patógeno desafiador. Os melhores isolados foram testados quanto à capacidade de reduzir os sintomas da ramulose e da murcha de Verticillium e de inibir diretamente os patógenos in vitro. Do total de 123 isolados de rizobactérias foram selecionados cinco, L2-1 (Bacillus cereus, MT5-6 (Bacillus cereus, L2-2 (Achromobacter xylosoxidans, MT5-5 (Bacillus cereus e MT5-11 (Brevibacterium sp., os quais apresentaram controle da mancha angular acima de 40%, em relação à testemunha. Nenhum isolado reduziu a severidade da ramulose e da murcha de Verticillium em relação à testemunha, nem apresentou efeito inibitório direto in vitro a X. axonopodis pv. malvacearum e Colletotrichum gossypii var. cephalosporioides. Para V. dahliae, apenas o isolado L2-1 apresentou efeito inibitório.The potential of rhizobacteria was evaluated for resistance induction against Xanthomonas axonopodis pv. malvacearum. After isolation, the rhizobacteria were screened for the reduction of angular leaf spot severity under greenhouse conditions. They were spatially separated from the challenging pathogen. The best isolates were tested for the capacity to reduce ramulose and Verticillium wilt severity and directly inhibit pathogens in vitro. From a total of 123 rhizobacterial isolates, five were selected, L2-1 (Bacillus cereus, MT5-6 (Bacillus cereus, L2-2 (Achromobacter xylosoxidans, MT5-5 (Bacillus cereus and MT5-11 (Brevibacterium sp., which showed angular leaf spot control above 40% as compared to the control. The tested isolates neither reduced the severity of ramulose and verticillium wilt compared to the control nor showed in vitro direct
Renata de Cássia Camara
Full Text Available Assays were done under greenhouse conditions in order to evaluate the effect of pyraclostrobin (0.0375, 0.0750 and 0.150 mL.L-1 and acibenzolar-S-methyl (ASM (0.025 g.L-1 in common bacterial blight, using leaves of snap beans cultivar Bragança. These chemicals were sprayed at three different times: five days before; five days before + five days after; and five days after leaf inoculation with an isolate of Xanthomonas axonopodis pv. phaseoli. They were determinate the levels of polyphenoloxidase, peroxidase and total soluble proteins on inoculated and non-inoculated leaves of snap beans sprayed with pyraclostrobin (0.075 g.L-1 and ASM (0.025 g.L-1. All concentration of pyraclostrobin and ASM reduced the area under the disease progress curve (AUDPC on leaves of snap beans, and the least AUDPC value was observed when this products were sprayed five days before + five days after inoculation. Higher levels of polyphenoloxidase, peroxidase and the total soluble proteins were observed on leaves sprayed with pyraclostrobin or ASM.Ensaios foram conduzidos sob condições de casa-de-vegetação para avaliar o efeito de pyraclostrobin (0,0375; 0.0750 e 0,150 mL.L-1 e acibenzolar-S-methyl (ASM (0.025 g.L-1 sobre o crestamento bacteriano comum, em folhas de feijão-vagem cultivar Bragança. Os produtos foram pulverizados em três diferentes períodos: cinco dias antes, cinco dias antes + cinco dias após e cinco dias após a inoculação dos folíolos com um isolado de Xanthomonas axonopodis pv. phaseoli. Foram determinados os teores de polifenoloxidase, peroxidase e proteínas solúveis totais em folhas inoculadas e não-inoculadas de feijão-vagem pulverizadas com pyraclostrobin (0,075 g.L-1 e ASM (0,025 g.L-1. Todas as concentrações de pyraclostrobin e ASM reduziram os valores da área abaixo da curva do progresso da doença (AUPDC e o menor valor da AUPDC foi observado para a aplicação dos produtos cinco dias antes + cinco dias após a inocula
Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J
The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009–2010 crop cycle. Total bacterial populations averaged between 105 and 106 per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial ‘core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment. PMID:22534606
Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J
The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009-2010 crop cycle. Total bacterial populations averaged between 10(5) and 10(6) per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial 'core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment.
James Lashomb; Alan Iskra; Ann Brooks Gould; George Hamilton
Bacterial leaf scorch (BLS) of amenity trees is caused by the bacterium Xylella fastidiosa, a xylem-limited pathogen that causes water stress resulting in leaf scorch, decline, and eventual death of affected trees. Recent surveys indicate that BLS is widespread throughout the eastern half of the United States. In New Jersey, BLS primarily affects red and pin oaks...
Cocoyam (Colocasia esculenta L). is an important edible tuber crop, but taro leaf blight caused by Phytophthora colocasiae has been the greatest constraint to cocoyam production in Nigeria since 2009. Field trials were conducted to determine the effect of fungicides and the spray regimes on leaf growth, disease incidence, ...
Jackson, Colin R; Randolph, Kevin C; Osborn, Shelly L; Tyler, Heather L
Plants harbor a diverse bacterial community, both as epiphytes on the plant surface and as endophytes within plant tissue. While some plant-associated bacteria act as plant pathogens or promote plant growth, others may be human pathogens. The aim of the current study was to determine the bacterial community composition of organic and conventionally grown leafy salad vegetables at the point of consumption using both culture-dependent and culture-independent methods. Total culturable bacteria on salad vegetables ranged from 8.0 × 10(3) to 5.5 × 10(8) CFU g(-1). The number of culturable endophytic bacteria from surface sterilized plants was significantly lower, ranging from 2.2 × 10(3) to 5.8 × 10(5) CFU g(-1). Cultured isolates belonged to six major bacterial phyla, and included representatives of Pseudomonas, Pantoea, Chryseobacterium, and Flavobacterium. Eleven different phyla and subphyla were identified by culture-independent pyrosequencing, with Gammaproteobacteria, Betaproteobacteria, and Bacteroidetes being the most dominant lineages. Other bacterial lineages identified (e.g. Firmicutes, Alphaproteobacteria, Acidobacteria, and Actinobacteria) typically represented less than 1% of sequences obtained. At the genus level, sequences classified as Pseudomonas were identified in all samples and this was often the most prevalent genus. Ralstonia sequences made up a greater portion of the community in surface sterilized than non-surface sterilized samples, indicating that it was largely endophytic, while Acinetobacter sequences appeared to be primarily associated with the leaf surface. Analysis of molecular variance indicated there were no significant differences in bacterial community composition between organic versus conventionally grown, or surface-sterilized versus non-sterilized leaf vegetables. While culture-independent pyrosequencing identified significantly more bacterial taxa, the dominant taxa from pyrosequence data were also detected by traditional
Patharkar, O Rahul; Gassmann, Walter; Walker, John C
Plants utilize an innate immune system to protect themselves from disease. While many molecular components of plant innate immunity resemble the innate immunity of animals, plants also have evolved a number of truly unique defense mechanisms, particularly at the physiological level. Plant's flexible developmental program allows them the unique ability to simply produce new organs as needed, affording them the ability to replace damaged organs. Here we develop a system to study pathogen-triggered leaf abscission in Arabidopsis. Cauline leaves infected with the bacterial pathogen Pseudomonas syringae abscise as part of the defense mechanism. Pseudomonas syringae lacking a functional type III secretion system fail to elicit an abscission response, suggesting that the abscission response is a novel form of immunity triggered by effectors. HAESA/HAESA-like 2, INFLORESCENCE DEFICIENT IN ABSCISSION, and NEVERSHED are all required for pathogen-triggered abscission to occur. Additionally phytoalexin deficient 4, enhanced disease susceptibility 1, salicylic acid induction-deficient 2, and senescence-associated gene 101 plants with mutations in genes necessary for bacterial defense and salicylic acid signaling, and NahG transgenic plants with low levels of salicylic acid fail to abscise cauline leaves normally. Bacteria that physically contact abscission zones trigger a strong abscission response; however, long-distance signals are also sent from distal infected tissue to the abscission zone, alerting the abscission zone of looming danger. We propose a threshold model regulating cauline leaf defense where minor infections are handled by limiting bacterial growth, but when an infection is deemed out of control, cauline leaves are shed. Together with previous results, our findings suggest that salicylic acid may regulate both pathogen- and drought-triggered leaf abscission.
Verstraete, Brecht; Janssens, Steven; Rønsted, Nina
Every plant species on Earth interacts in some way or another with microorganisms and it is well known that certain forms of symbiosis between different organisms can drive evolution. Within some clades of Rubiaceae (coffee family), a specific plant-bacteria interaction exists in which non-pathological endophytes are present in the leaves of their hosts. It is hypothesized that the bacterial endophytes, either alone or by interacting with the host, provide chemical protection against herbivory or pathogens by producing toxic or otherwise advantageous secondary metabolites. If the bacteria indeed have a direct beneficial influence on their hosts, it is reasonable to assume that the endophytes may increase the fitness of their hosts and therefore it is probable that their presence also has an influence on the long-term evolution of the particular plant lineages. In this study, the possible origin in time of non-nodulated bacterial leaf symbiosis in the Vanguerieae tribe of Rubiaceae is elucidated and dissimilarities in evolutionary dynamics between species with endophytes versus species without are investigated. Bacterial leaf symbiosis is shown to have most probably originated in the Late Miocene, a period when the savannah habitat is believed to have expanded on the African continent and herbivore pressure increased. The presence of bacterial leaf endophytes appears to be restricted to Old World lineages so far. Plant lineages with leaf endophytes show a significantly higher speciation rate than plant lineages without endophytes, while there is only a small difference in extinction rate. The transition rate shows that evolving towards having endophytes is twice as fast as evolving towards not having endophytes, suggesting that leaf symbiosis must be beneficial for the host plants. We conclude that the presence of bacterial leaf endophytes may also be an important driver for speciation of host plants. Copyright © 2017 Elsevier Inc. All rights reserved.
Truchado, Pilar; Gil, M Isabel; Reboleiro, Patricia; Rodelas, Belén; Allende, Ana
Solar radiation has been identified as a stress factor affecting phyllosphere associated bacteria colonization and survival during primary production. In the present study, the impact of different solar radiation doses on the phyllosphere microbiota of red-pigmented baby leaf lettuce cultivated in open field under commercial conditions was evaluated. Four weeks before harvest, the growing field was divided into four plots; each one was consecutively covered with one-week-interval with a light-excluding plastic to reduce the sunlight exposure. Four different solar radiation treatments were generated and cumulative photosynthetically active radiation (PAR) was used to differentiate treatments as follows: 4889 ± 428 μmol/m 2 /s (uncovered), 4265 ± 356 μmol/m 2 /s (covered for 1 week), 3602 ± 225 μmol/m 2 /s (covered for 2 weeks) and 3115 ± 313 μmol/m 2 /s (covered for 3 weeks). The size and composition of the phyllosphere bacterial community were determined by cultivation-depended (plate count) and independent (qPCR) techniques. Exposure to decreased levels of cumulative PAR did not produce significant differences in total bacterial community size, regardless of the chosen quantification techniques. However, total bacteria size quantified by qPCR was around 3.5 orders of magnitude higher than those obtained by plate count. The observed differences between cultivation-depended and independent techniques could be attributed to the presence of non-viable or viable but non-culturable (VBNC) bacteria. The bacterial community structure was analyzed using temperature gradient gel electrophoresis (TGGE), and significant differences were detected when the four solar treatment were compared. A qPCR approach was applied to the quantification of specific bacterial phyla and classes, previously identified in the phyllosphere of plants available literature, confirming that Proteobacteria, Bacteroidetes, Actinobacterias and Firmicutes were the most abundantly
Full Text Available Strawberry bacterial angular leaf spot (ALS disease, caused by Xanthomonas fragariae has become increasingly problematic in the strawberry agro-industry. ALS causes small angular water-soaked lesions to develop on the abaxial leaf surface. Studies reported optimum temperature conditions for X. fragariae are 20°C and the pathogen suffers mortality above 32°C. However, at the nursery stage, disease symptoms have been observed under high temperature conditions. In the present study, results showed X. fragariae transmission was via infected maternal plants, precipitation, and sprinkler irrigation systems. Systemic infections were detected using X. fragariae specific primers 245A/B and 295A/B, where 300-bp and 615-bp were respectively amplified. During the nursery stage (from May to August, the pathogen was PCR detected only in maternal plants, but not in soil or irrigation water through the nursery stage. During the cultivation period, from September to March, the pathogen was detected in maternal plants, progeny, and soil, but not in water. Additionally, un-infected plants, when planted with infected plants were positive for X. fragariae via PCR at the late cultivation stage. Chemical control for X. fragariae with oxolinic acid showed 87% control effects against the disease during the nursery period, in contrast to validamycin-A, which exhibited increased efficacy against the disease during the cultivation stage (control effect 95%. To our knowledge, this is the first epidemiological study of X. fragariae in Korean strawberry fields.
Purahong, Witoon; Kapturska, Danuta; Pecyna, Marek J; Jariyavidyanont, Katalee; Kaunzner, Jennifer; Juncheed, Kantida; Uengwetwanit, Tanaporn; Rudloff, Renate; Schulz, Elke; Hofrichter, Martin; Schloter, Michael; Krüger, Dirk; Buscot, François
Forest management practices (FMPs) significantly influence important ecological processes and services in Central European forests, such as leaf litter decomposition and nutrient cycling. Changes in leaf litter diversity, and thus, its quality as well as microbial community structure and function induced by different FMPs were hypothesized to be the main drivers causing shifts in decomposition rates and nutrient release in managed forests. In a litterbag experiment lasting 473 days, we aimed to investigate the effects of FMPs (even-aged timber management, selective logging and unmanaged) on bacterial and fungal communities involved in leaf litter degradation over time. Our results showed that microbial communities in leaf litter were strongly influenced by both FMPs and sampling date. The results from nonmetric multidimensional scaling (NMDS) ordination revealed distinct patterns of bacterial and fungal successions over time in leaf litter. We demonstrated that FMPs and sampling dates can influence a range of factors, including leaf litter quality, microbial macronutrients, and pH, which significantly correlate with microbial community successions.
Blueberry bacterial leaf scorch (BBLS) disease, a threat to blueberry production in the Southern USA and potentially elsewhere, is caused by Xylella fastidiosa. Efficient control of BBLS requires knowledge of the pathogen. However, this is challenging because Xylella fastidiosa is difficult to cultu...
Dali L. Gaganidze
Full Text Available Fire blight is distinguished among the fruit tree diseases by harmfulness. Fire blight damages about 180 cultural and wild plants belonging to the Rosaceae family. Quince, apple and pear are the most susceptible to the disease. At present, the disease occurs in over 40 countries of Europe and Asia. Economic damage caused by fire blight is expressed not only in crop losses, but also, it poses threat of eradication to entire fruit tree gardens. Erwinia amylovora, causative bacteria of fire blight in fruit trees, is included in the A2 list of quarantine organisms. In 2016, the employees of the Plant Pest Diagnostic Department of the Laboratory of the Georgian Ministry of Agriculture have detected Erwinia amylovora in apple seedlings from Mtskheta district. National Food Agency, Ministry of Agriculture of Georgia informed FAO on pathogen detection. The aim of the study is detection of the bacterium Erwinia amylovora by molecular method (PCR in the samples of fruit trees, suspicious on fire blight collected in the regions of Eastern (Kvemo Kartli, Shida Kartli and Kakheti and Western Georgia (Imereti.The bacterium Erwinia amylovora was detected by real time and conventional PCR methods using specific primers and thus the fire blight disease confirmed in 23 samples of plant material from Shida Kartli (11 apples, 6 pear and 6 quince samples, in 5 samples from Kvemo Kartli (1 quince and 4 apple samples, in 2 samples of apples from Kakheti region and 1 sample of pear collected in Imereti (Zestafoni. Keywords: Fire blight, Erwinia amylovora, Conventional PCR, Real time PCR, DNA, Bacterium
Aylward, Frank O.; Burnum, Kristin E.; Scott, Jarrod J.; Suen, Garret; Tringe, Susannah G.; Adams, Sandra M.; Barry, Kerrie W.; Nicora, Carrie D.; Piehowski, Paul D.; Purvine, Samuel O.; Starrett, Gabriel J.; Goodwin, Lynne A.; Smith, Richard D.; Lipton, Mary S.; Currie, Cameron R.
Herbivores gain access to nutrients stored in plant biomass largely by harnessing the metabolic activities of microbes. Leaf-cutter ants of the genus Atta are a hallmark example; these dominant Neotropical herbivores cultivate symbiotic fungus gardens on massive quantities of fresh plant forage. As the external digestive system of the ants, fungus gardens facilitate the production and sustenance of millions of workers in mature Atta colonies. Here we use metagenomic, and metaproteomic techniques to characterize the bacterial diversity and overall physiological potential of fungus gardens from two species of Atta. Our analysis of over 1.2 Gbp of community metagenomic sequence and three 16S pyrotag libraries reveals that, in addition to harboring the dominant fungal crop, these ecosystems contain abundant populations of Enterobacteriaceae, including the genera Enterobacter, Pantoea, Klebsiella, Citrobacter, and Escherichia. We show that these bacterial communities possess genes commonly associated with lignocellulose degradation, and likely participate in the processing of plant biomass. Additionally, we demonstrate that bacteria in these environments encode a diverse suite of biosynthetic pathways, and that they may enrich the nitrogen-poor forage of the ants with B-vitamins, amino acids, and proteins. These results are consistent with the hypothesis that fungus gardens are highly-specialized fungus-bacteria communities that efficiently convert plant material into usable energy for their ant hosts. Together with recent investigations into the microbial symbionts of vertebrates, our work underscores the importance of microbial communities to the ecology and evolution of herbivorous metazoans.
Zeng, J; Cao, W; Fedak, G; Sun, S; McCallum, B; Fetch, T; Xue, A; Zhou, Y
Thinopyrum intermedium, a wild relative of wheat, is an excellent source of disease resistance. Two novel partial amphiploids, 08-47-50 and 08-53-55 (2n = 6x = 42), were developed from wide crosses between durum wheat and Th. intermedium. Meiotic analysis showed that pollen mother cells of the two partial amphiploids formed an average 20.49 bivalents for 08-47-50 and 20.67 bivalents for 08-53-55, indicating that they are basically cytologically stable. GISH analysis revealed that the two partial amphiploids carried different chromosome compositions. 08-47-50 had fourteen chromosomes from Th. intermedium and its alien chromosomes included six St-, four E(e) - and four E(e)-St translocated chromosomes, whereas 08-53-55 had four St- and ten E(e)-St translocated chromosomes. Fungal disease evaluation indicated that both partial amphiploids had a high level of resistance to FHB, leaf rust and stem rust race Ug99. These two novel partial amphiploids with multiple disease resistance could be used as a new source of multiple disease resistance in bread wheat and durum wheat breeding programs. © 2013 The Authors.
Ding, Tao; Melcher, Ulrich
Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant's growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.
Full Text Available Bacteria are known to be associated endophytically with plants. Research on endophytic bacteria has identified their importance in food safety, agricultural production and phytoremediation. However, the diversity of endophytic bacterial communities and the forces that shape their compositions in non-cultivated plants are largely uncharacterized. In this study, we explored the diversity, community structure, and dynamics of endophytic bacteria in different plant species in the Tallgrass Prairie Preserve of northern Oklahoma, USA. High throughput sequencing of amplified segments of bacterial rDNA from 81 samples collected at four sampling times from five plant species at four locations identified 335 distinct OTUs at 97% sequence similarity, representing 16 phyla. Proteobacteria was the dominant phylum in the communities, followed by the phyla Bacteriodetes and Actinobacteria. Bacteria from four classes of Proteobacteria were detected with Alphaproteobacteria as the dominant class. Analysis of molecular variance revealed that host plant species and collecting date had significant influences on the compositions of the leaf endophytic bacterial communities. The proportion of Alphaproteobacteria was much higher in the communities from Asclepias viridis than from other plant species and differed from month to month. The most dominant bacterial groups identified in LDA Effect Size analysis showed host-specific patterns, indicating mutual selection between host plants and endophytic bacteria and that leaf endophytic bacterial compositions were dynamic, varying with the host plant's growing season in three distinct patterns. In summary, next generation sequencing has revealed variations in the taxonomic compositions of leaf endophytic bacterial communities dependent primarily on the nature of the plant host species.
Full Text Available Plant endophytic bacteria play an important role in plant growth and health. In the context of climate change, the response of plant endophytic bacterial communities to elevated CO2 at different rice growing stages is poorly understood. Using 454 pyrosequencing, we investigated the response of leaf endophytic bacterial communities to elevated CO2 (eCO2 at the tillering, filling and maturity stages of the rice plant under different nitrogen fertilization conditions (low nitrogen fertilization (LN and high nitrogen fertilization (HN. The results revealed that the leaf endophytic bacterial community was dominated by Gammaproteobacteria-affiliated families, such as Enterobacteriaceae and Xanthomonadaceae, which represent 28.7-86.8% and 2.14-42.6% of the total sequence reads, respectively, at all tested growth stages. The difference in the bacterial community structure between the different growth stages was greater than the difference resulting from the CO2 and nitrogen fertilization treatments. The eCO2 effect on the bacterial communities differed greatly under different nitrogen application conditions and at different growth stages. Specifically, eCO2 revealed a significant effect on the community structure under both LN and HN levels at the tillering stage; however, the significant effect of eCO2 was only observed under HN, rather than under the LN condition at the filling stage; no significant effect of eCO2 on the community structure at both the LN and HN fertilization levels was found at the maturity stage. These results provide useful insights into the response of leaf endophytic bacterial communities to elevated CO2 across rice growth stages.
Comportamento de genótipos de cenoura para verão em localidades com diferentes etiologias da queima-das-folhas Behavior of summer carrot genotypes in fields with different etiologies of the leaf blight complex
Carlos Alberto Lopes
Full Text Available Treze genótipos de cenoura de verão foram avaliados em 1997 e 1998 para a resistência ao complexo etiológico da queima-das-folhas em seis localidades apresentando infecção natural com os diferentes componentes deste complexo. Alternaria dauci foi o patógeno mais frequente, presente em todas as localidades e predominando em quatro delas. Cercospora carotae foi encontrado em três dos seis locais, prevalecendo em um deles. Estes dois patógenos estavam presentes em proporções similares em um dos locais. Xanthomonas campestris pv. carotae foi observada em todas as localidades, porém em intensidade sempre menor do que os dois fungos, sempre que estes últimos se encontravam presentes. Os genótipos 'Brasília', 'Alvorada', 'Tropical', 'Carandaí' e 'Kuronan', foram os mais resistentes, independentemente da composição local do complexo etiológico da doença. As cultivares Nova Kuroda e Prima foram as mais suscetíveis à doença.Thirteen carrot genotypes were evaluated for their resistance to the leaf blight complex in six locations in Brazil. The assessments were carried out under field conditions, in the summer of 1997 and 1998, in plots where each of the pathogens were involved differentially in the composition of the complex. Alternaria dauci was the most frequent pathogen, being found in all locations and predominating in four of them. Cercospora carotae was found in three out of the six locations, predominating in one of them. These two species were found in equal proportions in one field. Xanthomonas campestris pv. carotae was present in all sampled plots, but in lower intensity when compared to the two fungi. The cultivars Brasilia, Alvorada, Tropical, Carandai and Kuronan were the most resistant, independently of the composition of the pathological complex. 'Nova Kuroda' and 'Prima' were the most susceptible.
Leonardo De La Fuente
Full Text Available Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen.
De La Fuente, Leonardo; Parker, Jennifer K.; Oliver, Jonathan E.; Granger, Shea; Brannen, Phillip M.; van Santen, Edzard; Cobine, Paul A.
Xylella fastidiosa is a plant pathogenic bacterium that lives inside the host xylem vessels, where it forms biofilm believed to be responsible for disrupting the passage of water and nutrients. Here, Nicotiana tabacum was infected with X. fastidiosa, and the spatial and temporal changes in the whole-leaf ionome (i.e. the mineral and trace element composition) were measured as the host plant transitioned from healthy to diseased physiological status. The elemental composition of leaves was used as an indicator of the physiological changes in the host at a specific time and relative position during plant development. Bacterial infection was found to cause significant increases in concentrations of calcium prior to the appearance of symptoms and decreases in concentrations of phosphorous after symptoms appeared. Field-collected leaves from multiple varieties of grape, blueberry, and pecan plants grown in different locations over a four-year period in the Southeastern US showed the same alterations in Ca and P. This descriptive ionomics approach characterizes the existence of a mineral element-based response to X. fastidiosa using a model system suitable for further manipulation to uncover additional details of the role of mineral elements during plant-pathogen interactions. This is the first report on the dynamics of changes in the ionome of the host plant throughout the process of infection by a pathogen. PMID:23667547
Ikeda, Seishi; Anda, Mizue; Inaba, Shoko; Eda, Shima; Sato, Shusei; Sasaki, Kazuhiro; Tabata, Satoshi; Mitsui, Hisayuki; Sato, Tadashi; Shinano, Takuro; Minamisawa, Kiwamu
The diversities leaf-associated bacteria on nonnodulated (Nod(-)), wild-type nodulated (Nod(+)), and hypernodulated (Nod(++)) soybeans were evaluated by clone library analyses of the 16S rRNA gene. To analyze the impact of nitrogen fertilization on the bacterial leaf community, soybeans were treated with standard nitrogen (SN) (15 kg N ha(-1)) or heavy nitrogen (HN) (615 kg N ha(-1)) fertilization. Under SN fertilization, the relative abundance of Alphaproteobacteria was significantly higher in Nod(-) and Nod(++) soybeans (82% to 96%) than in Nod(+) soybeans (54%). The community structure of leaf-associated bacteria in Nod(+) soybeans was almost unaffected by the levels of nitrogen fertilization. However, differences were visible in Nod(-) and Nod(++) soybeans. HN fertilization drastically decreased the relative abundance of Alphaproteobacteria in Nod(-) and Nod(++) soybeans (46% to 76%) and, conversely, increased those of Gammaproteobacteria and Firmicutes in these mutant soybeans. In the Alphaproteobacteria, cluster analyses identified two operational taxonomic units (OTUs) (Aurantimonas sp. and Methylobacterium sp.) that were especially sensitive to nodulation phenotypes under SN fertilization and to nitrogen fertilization levels. Arbuscular mycorrhizal infection was not observed on the root tissues examined, presumably due to the rotation of paddy and upland fields. These results suggest that a subpopulation of leaf-associated bacteria in wild-type Nod(+) soybeans is controlled in similar ways through the systemic regulation of autoregulation of nodulation, which interferes with the impacts of N levels on the bacterial community of soybean leaves.
Ellur, Ranjith K; Khanna, Apurva; S, Gopala Krishnan; Bhowmick, Prolay K; Vinod, K K; Nagarajan, M; Mondal, Kalyan K; Singh, Nagendra K; Singh, Kuldeep; Prabhu, Kumble Vinod; Singh, Ashok K
Basmati rice is preferred internationally because of its appealing taste, mouth feel and aroma. Pusa Basmati 1121 (PB1121) is a widely grown variety known for its excellent grain and cooking quality in the international and domestic market. It contributes approximately USD 3 billion to India's forex earning annually by being the most traded variety. However, PB1121 is highly susceptible to bacterial blight (BB) disease. A novel BB resistance gene Xa38 was incorporated in PB1121 from donor parent PR114-Xa38 using a modified marker-assisted backcross breeding (MABB) scheme. Phenotypic selection prior to background selection was instrumental in identifying the novel recombinants with maximum recovery of recurrent parent phenome. The strategy was effective in delimiting the linkage drag to <0.5 mb upstream and <1.9 mb downstream of Xa38 with recurrent parent genome recovery upto 96.9% in the developed NILs. The NILs of PB1121 carrying Xa38 were compared with PB1121 NILs carrying xa13 + Xa21 (developed earlier in our lab) for their resistance to BB. Both NILs showed resistance against the Xoo races 1, 2, 3 and 6. Additionally, Xa38 also resisted Xoo race 5 to which xa13 + Xa21 was susceptible. The PB1121 NILs carrying Xa38 gene will provide effective control of BB in the Basmati growing region.
Kang, In Jeong; Kang, Mi-Hyung; Noh, Tae-Hwan; Shim, Hyeong Kwon; Shin, Dong Bum; Heu, Suggi
Burkholderia glumae (bacterial grain rot), Xanthomonas oryzae pv. oryzae (bacterial leaf blight), and Acidovorax avenae subsp. avenae (bacterial brown stripe) are major seedborne pathogens of rice. Based on the 16S and 23S rDNA sequences for A. avenae subsp. avenae and B. glumae, and transposase A gene sequence for X. oryzae pv. oryzae, three sets of primers had been designed to produce 402 bp for B. glumae, 490 bp for X. oryzae, and 290 bp for A. avenae subsp. avenae with the 63°C as an opti...
Yadav, R K P; Karamanoli, K; Vokou, D
In this study, we assessed various leaf structural and chemical features as possible predictors of the size of the phyllosphere bacterial population in the Mediterranean environment. We examined eight perennial species, naturally occurring and coexisting in the same area, in Halkidiki (northern Greece). They are Arbutus unedo, Quercus coccifera, Pistacia lentiscus, and Myrtus communis (evergreen sclerophyllous species), Lavandula stoechas and Cistus incanus (drought semi-deciduous species), and Calamintha nepeta and Melissa officinalis (non-woody perennial species). M. communis, L. stoechas, C. nepeta, and M. officinalis produce essential oil in substantial quantities. We sampled summer leaves from these species and (1) estimated the size of the bacterial population of their phyllosphere, (2) estimated the concentration of different leaf constituents, and (3) studied leaf morphological and anatomical features and expressed them in a quantitative way. The aromatic plants are on average more highly colonized than the other species, whereas the non-woody perennials are more highly colonized than the woody species. The population size of epiphytic bacteria is positively correlated with glandular and non-glandular trichome densities, and with water and phosphorus contents; it is negatively correlated with total phenolics content and the thickness of the leaf, of the mesophyll, and of the abaxial epidermis. No correlation was found with the density of stomata, the nitrogen, and the soluble sugar contents. By regression tree analysis, we found that the leaf-microbe system can be effectively described by three leaf attributes with leaf water content being the primary explanatory attribute. Leaves with water content >73% are the most highly colonized. For leaves with water content 1.34 mg g(-1) d.w.) are more colonized, and leaves with the adaxial epidermis thicker than 20.77 microm are the least colonized. Although these critical attributes and values hold true only within
Full Text Available Objective: To evaluate the phytochemical properties and antibacterial activity of methanol, acetone, ethanol and aqueous extracts of fresh leaves of Spondias mombin (S. mombin on some clinical bacterial isolates. Methods: Clean and fresh leaves of S. mombin were collected in Ondo, Southwestern Nigeria. The leaves were blended, extracted with methanol, acetone, ethanol and water. The extracts were evaporated to dryness using rotary evaporator and tested for the presence of saponins, tannins, cardiac glycoside, terpenoids, flavonoids, reducing sugars, volatile oils, alkaloids and glycoside. The extract were tested against Gram-negative bacteria Klebsiella pneumonia, Serratia marcescens, Salmonella typhi and Enterobacter aerogens; Gram-positive bacteria Staphylococcus aureus by observing the zones of inhibition using agar well diffusion assay. Results: The study showed that the leaves contained saponins, tannins, flavonoids, alkaloids and glycoside. All the solvent extracts showed activity against all the test bacteria. The methanol extract also showed the highest activity against Enterobacter aerogens, zone of diameter (15.00 依1.89 mm, while the ethanol extract showed the highest activity against Staphylococcus aureus with zone of diameter (12.50依1.50 mm. The acetone extract showed the highest activity against Salmonella typhi, zone of diameter (17.50依0.29 mm followed by methanol extract showing zone of diameter (15.67依1.01 mm. The acetone extract showed the highest activity against Klebsiella pneumonia (15.17依0.67 mm, while the aqueous extract shows the highest activity against Serratia marcescens (14.67依2.68 mm. The minimum inhibitory concentration of the leaf extracts ranged between 10-90 mg/mL. Conclusions: This study showed that the aqueous and organic solvents extract of fresh leaves of S. mombin has anti-microbial activity against all the tested organisms.
Fire blight (Erwinia amylovora) is a devastating bacterial disease in apple that results in severe economic losses. Epidemics are becoming more common as susceptible cultivars and rootstocks are being planted, and control is becoming more difficult as antibiotic-resistant strains develop. Resistan...
Yong Ho Choi
Full Text Available Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4-linked D-glucosamine and Nacetyl- D-glucosamine. There have been many reports on the induced systemic resistance and in vivo antifungal activities of higher molecular weight chitosans with molecular weights over 3,000 amu (atomatic mass unit, but there are few papers on in vivo antifungal activities of low molecular weight chitosans (oligochitosans with molecular weights less than 3,000 amu. In our study, an oligochitosan sample (320?3,000 amu showed a potent 1-day protective activity with control values more than 94% at concentrations of 500 and 1,000 ?g/ml especially against tomato late blight caused by Phytophthora infestans under growth chamber conditions. It also displayed a moderate 1-day protective activity with control values of 67?89% at concentrations of 500 and 1,000 ?g/ml against wheat leaf rust and red pepper anthracnose. On the other hand, it showed a 16-hr curative activity against red pepper anthracnose, but not against tomato late blight and wheat leaf rust. In field experiments, oligochitosan effectively suppressed the development of late blight on potato and tomato plants with control values of 72% and 48%, respectively. The results strongly indicate that oligochitosan can be used as an eco-friendly organic material for the control of late blight on tomato and potato plants.
Simonetti, E; Carmona, M A; Scandiani, M M; García, A F; Luque, A G; Correa, O S; Balestrasse, K B
Assessment of biological control of Cercospora sojina, causal agent of frogeye leaf spot (FLS) of soya bean, using three indigenous bacterial strains, BNM297 (Pseudomonas fluorescens), BNM340 and BNM122 (Bacillus amyloliquefaciens). From cultures of each bacterial strain, cell suspensions and cell-free supernatants were obtained and assayed to determine their antifungal activity against C. sojina. Both mycelial growth and spore germination in vitro were more strongly inhibited by bacterial cell suspensions than by cell-free supernatants. The Bacillus strains BNM122 and BNM340 inhibited the fungal growth to a similar degree (I ≈ 52-53%), while cells from P. fluorescens BNM297 caused a lesser reduction (I ≈ 32-34%) in the fungus colony diameter. The foliar application of the two Bacillus strains on soya bean seedlings, under greenhouse conditions, significantly reduced the disease severity with respect to control soya bean seedlings and those sprayed with BNM297. This last bacterial strain was not effective in controlling FLS in vivo. Our data demonstrate that the application of antagonistic bacteria may be a promising and environmentally friendly alternative to control the FLS of soya bean. To our knowledge, this is the first report of biological control of C. sojina by using native Bacillus strains. © 2012 The Authors. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.
Talei, D.; Fotokian, M. H.
Bacterial stripe as a new rice disease in Iran is more frequent nowadays. The objective of this study was to assessment of resistance in rice varieties together with evaluating of zymogram bands resulted from SDS PAGE electrophoresis of leaf proteins. For this purpose, 30 lines were tested in a randomized complete block design with three replications. The analysis of variance showed that there was significant difference between genotypes for resistance. Mean compare based on field results revealed that Domsiyah had the lowest resistance while Nemat and 7162 demonstrated the highest resistance. Laboratory results showed that there were significant difference between protein bands resulted from sensitive and resistance verities. Twenty bands were observed through SDS PAGE electrophoresis of leaf proteins. The 9th and 12th bands were found in sensitive varieties while were not in resistance genotypes. According to the results of this study, 7162 variety can be considered as the sources of resistance in breeding programs. Meanwhile attending to existence of 9th and 12th bands in sensitive varieties, resistance against bacterial stripe of rice maybe influenced by absence of these proteins.
Trujillo, César A; Arias-Rojas, Nathalia; Poulin, Lucie; Medina, César A; Tapiero, Anibal; Restrepo, Silvia; Koebnik, Ralf; Bernal, Adriana J
Molecular typing of pathogen populations is an important tool for the development of effective strategies for disease control. Diverse molecular markers have been used to characterize populations of Xanthomonas axonopodis pv. manihotis (Xam), the main bacterial pathogen of cassava. Recently, diversity and population dynamics of Xam in the Colombian Caribbean coast were estimated using AFLPs, where populations were found to be dynamic, diverse and with haplotypes unstable across time. Aiming to examine the current state of pathogen populations located in the Colombian Eastern Plains, we also used AFLP markers and we evaluated the usefulness of Variable Number Tandem Repeats (VNTRs) as new molecular markers for the study of Xam populations. The population analyses showed that AFLP and VNTR provide a detailed and congruent description of Xam populations from the Colombian Eastern Plains. These two typing strategies clearly separated strains from the Colombian Eastern Plains into distinct populations probably because of geographical distance. Although the majority of analyses were congruent between typing markers, fewer VNTRs were needed to detect a higher number of genetic populations of the pathogen as well as a higher genetic flow among sampled locations than those detected by AFLPs. This study shows the advantages of VNTRs over AFLPs in the surveillance of pathogen populations and suggests the implementation of VNTRs in studies that involve large numbers of Xam isolates in order to obtain a more detailed overview of the pathogen to improve the strategies for disease control.
A new leaf rot disease of tobacco was found in fields of the Shaowu region, Fujian Province of China in 2015. A typical symptom was necrosis along the main or lateral veins of tobacco leaves, eventually causing wilting and death of the leaves, while the necrosis spread no further than the epidermis ...
Panneerselvam, Chellasamy; Murugan, Kadarkarai; Kovendan, Kalimuthu; Kumar, Palanisamy Mahesh; Ponarulselvam, Sekar; Amerasan, Duraisamy; Subramaniam, Jayapal; Hwang, Jiang-Shiou
To explore the larvicidal activity of Catharanthus roseus (C. roseus) leaf extract and Bacillus thuringiensis (B. thuringiensis) against the malarial vector Anopheles stephensi (An. stephensi), when being used alone or together. The larvicidal activity was assayed at various concentrations under the laboratory and field conditions. The LC50 and LC90 values of the C. roseus leaf extract were determined by probit analysis. The plant extract showed larvicidal effects after 24 h of exposure; however, the highest larval mortality was found in the petroleum ether extract of C. roseus against the first to fourth instars larvae with LC50=3.34, 4.48, 5.90 and 8.17 g/L, respectively; B. thuringiensis against the first to fourth instars larvae with LC50=1.72, 1.93, 2.17 and 2.42 g/L, respectively; and the combined treatment with LC50=2.18, 2.41, 2.76 and 3.22 g/L, respectively. No mortality was observed in the control. The petroleum ether extract of C. roseus extract and B. thuringiensis have potential to be used as ideal eco-friendly agents for the control of An. stephensi in vector control programs. The combined treatment with this plant crude extract and bacterial toxin has better larvicidal efficacy against An. stephensi. Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.
Abi Soares Anjos Marques
Full Text Available Um dos fatores limitantes ao cultivo da goiabeira no Brasil é a 'seca dos ponteiros', causada por Erwinia psidii, presente nas regiões Sudeste e Centro-Oeste, onde se concentram grandes áreas produtoras. Considerando a pequena disponibilidade de informações sobre a epidemiologia e níveis de incidência dessa bacteriose, este estudo teve como objetivos: confirmar a distribuição e verificar a dispersão da seca dos ponteiros da goiabeira no Distrito Federal; investigar o efeito da temperatura sobre a multiplicação in vitro de E. psidii; desenvolver um teste de patogenicidade prático e eficiente e avaliar a sobrevivência in vitro da bactéria em diferentes substratos. A doença foi identificada em 56% das propriedades produtoras avaliadas no DF, com 81,9% de correlação entre a presença de sintomas e o diagnóstico laboratorial. A melhor faixa de temperatura para multiplicação de E. psidii foi de 24 a 33 ºC, e a bactéria permaneceu viável por até 120 dias em suspensão em água. A inoculação da bactéria em folhas ou hastes destacadas levou ao aparecimento de sintomas a partir do sétimo dia e mostrou-se eficiente como um teste rápido para se avaliar a patogenicidade de isolados.A major disease that affects guava is 'bacterial blight', caused by Erwinia psidii, which has been reported in Southeastern and Central Regions of Brazil where the major producing areas are located. Considering the lack of information on epidemiology and incidence levels of this disease, the objectives of this study were to confirm the presence and to verify the spread of the disease in Distrito Federal (DF; to determine optimal temperature for in vitro multiplication of E. psidii; to develop a simple and effective method for pathogenicity testing and to evaluate in vitro bacterial survival on different substrates. The disease was detected in 56% of producing orchards evaluated in DF, with a correlation of 81, 9% between presence of symptoms and
Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...
Pecan bacterial leaf scorch (PBLS) is a chronic disease that can cause major yield losses in pecan orchards. In the 2015-16 growing seasons, symptoms consistent with PBLS were observed in commercial pecan cultivars in AZ, NM, CA and TX. Symptoms included tan to light brown necrotic lesions, which ...
Tecon, R.; Leveau, J.H.J.
Bacteria that colonize the leaves of terrestrial plants often occur in clusters whose size varies from a few to thousands of cells. For the formation of such bacterial clusters, two non-mutually exclusive but very different mechanisms may be proposed: aggregation of multiple cells or clonal
Bacterial spot of tomato (BST) is a major constraint to tomato production in Ethiopia and many other countries leading to significant crop losses. In the present study, using pathogenicity tests, sensitivity to copper and streptomycin, and multilocus sequence analysis, a diverse group of Xanthomonas...
genomics. The acquired knowledge in the last years for this pathosystem will help to establish better disease control strategies and generate, in a short term, resistant cassava varieties contributing to solve one of the main problems of poor cassava farmers and this effort will open a new horizon to the cassava crop in the world.
W. James Grichar
Full Text Available Field studies were conducted in 2013 and 2014 in south Texas near Yoakum and from 2008 to 2011 in central Texas near Stephenville to evaluate various fungicides for foliar and soilborne disease control as well as peanut yield response under irrigation. Control of Sclerotinia blight caused by Sclerotinia minor Jagger with penthiopyrad at 1.78 L/ha was comparable to fluazinam or boscalid; however, the 1.2 L/ha dose of penthiopyrad did not provide consistent control. Peanut yield was reduced with the lower penthiopyrad dose when compared with boscalid, fluazinam, or the high dose of penthiopyrad. Control of early leaf spot, caused by Cercospora arachidicola S. Hori or southern blight, caused by Sclerotium rolfsii Sacc., with penthiopyrad in a systems approach was comparable with propiconazole, prothioconazole, or pyraclostrobin systems and resulted in disease control that was higher than the nontreated control. Peanut yield was also comparable with the penthiopyrad, propiconazole, prothioconazole, or pyraclostrobin systems and reflects the ability of the newer fungicides to control multiple diseases found in Texas peanut production.
Linhagens de feijoeiro comum com fenótipos agronômicos favoráveis e resistência ao crestamento bacteriano comum e antracnose Common bean lines with suitable agronomic phenotypes and resistant to bacterial blight and anthracnose
Joaquim Geraldo Cáprio da Costa
Full Text Available O crestamento bacteriano comum e a antracnoseincitados por Xanthomonas axonopodis pv. phaseoli (Smith Vauterin, Hoste, Kesters & Swings e Colletotrichum lindemuthianum (Sacc. & Magn. Scrib., respectivamente, podem reduzir consideravelmente a produtividade do feijoeiro comum (Phaseolus vulgaris L.. Conduziu-se este trabalho com o objetivo de obter linhagens com resistência conjunta ao crestamento bacteriano comum e à antracnose, com características agronômicas desejáveis. Foram obtidas 35 populações F2 provenientes de cruzamentos simples entre linhagens com resistência ao crestamento bacteriano comum proveniente de P. acutifolius A. Gray e linhagens resistentes à antracnose e com características agronômicas favoráveis. As populações segregantes de F2 a F5 foram inoculadas com o patótipo 89 de C. lindemuthianum com uma concentração de 1,2 x 10(6 conídios/mL e submetidas à seleção massal modificada. As plantas que apresentaram grau superior a 4 foram eliminadas. Na geração F5, foi realizada seleção individual das plantas remanescentes para obter as famílias F6. As famílias F6 foram avaliadas mediante inoculação com os patótipos 55, 89, 95 e 453 de C. lindemuthianum. As famílias F7 resistentes à antracnose foram inoculadas em casa-de-vegetação por incisão das folhas primárias com tesoura mergulhada em uma suspensão de 5 x 10(7 ufc do isolado XpCNF 15 de X. axonopodis pv. phaseoli. As linhagens resistentes foram avaliadas em quatro experimentos de campo. Foram selecionadas 17 linhagens com alto rendimento de grãos, resistentes ao crestamento bacteriano comum e à antracnose, com boa altura de inserção das vagens inferiores e resistentes ao acamamento.Common bacterial blight and anthracnose diseases, incited by Xanthomonas axonopodis pv. phaseoli (Smith Vauterin, Hoste, Kesters & Swings and Colletotrichum lindemuthianum (Sacc. & Magn. Scrib., respectively, are major constrains for dry bean (Phaseolus vulgaris L
Marsh, Sarah E; Poulsen, Michael; Pinto-Tomás, Adrián; Currie, Cameron R
Stable associations between partners over time are critical for the evolution of mutualism. Hosts employ a variety of mechanisms to maintain specificity with bacterial associates. Acromyrmex leaf-cutting ants farm a fungal cultivar as their primary nutrient source. These ants also carry a Pseudonocardia Actinobacteria exosymbiont on their bodies that produces antifungal compounds that help inhibit specialized parasites of the ants' fungal garden. Major workers emerge from their pupal cases (eclose) symbiont-free, but exhibit visible Actinobacterial coverage within 14 days post-eclosion. Using subcolony experiments, we investigate exosymbiont transmission within Acromyrmex colonies. We found successful transmission to newly eclosed major workers fostered by major workers with visible Actinobacteria in all cases (100% acquiring, n = 19). In contrast, newly eclosed major workers reared without exosymbiont-carrying major workers did not acquire visible Actinobacteria (0% acquiring, n = 73). We further show that the majority of ants exposed to major workers with exosymbionts within 2 hours of eclosion acquired bacteria (60.7% acquiring, n = 28), while normal acquisition did not occur when exposure occurred later than 2 hours post-eclosion (0% acquiring, n = 18). Our findings show that transmission of exosymbionts to newly eclosed major workers occurs through interactions with exosymbiont-covered workers within a narrow time window after eclosion. This mode of transmission likely helps ensure the defensive function within colonies, as well as specificity and partner fidelity in the ant-bacterium association.
Full Text Available Rxo1 cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxo1 was digested with Sca I and NgoM IV and the double right-border binary vector pMNDRBBin6 was digested with Hpa I and Xma I. pMNDRBBin6 carrying the gene Rxo1 was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxo1 gene had been cloned into pMNDRBBin6. This double right-border binary vector, named as pMNDRBBin6-Rxo1, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.
Ikeda, Seishi; Anda, Mizue; Inaba, Shoko; Eda, Shima; Sato, Shusei; Sasaki, Kazuhiro; Tabata, Satoshi; Mitsui, Hisayuki; Sato, Tadashi; Shinano, Takuro; Minamisawa, Kiwamu
The diversities leaf-associated bacteria on nonnodulated (Nod−), wild-type nodulated (Nod+), and hypernodulated (Nod++) soybeans were evaluated by clone library analyses of the 16S rRNA gene. To analyze the impact of nitrogen fertilization on the bacterial leaf community, soybeans were treated with standard nitrogen (SN) (15 kg N ha−1) or heavy nitrogen (HN) (615 kg N ha−1) fertilization. Under SN fertilization, the relative abundance of Alphaproteobacteria was significantly higher in Nod− and Nod++ soybeans (82% to 96%) than in Nod+ soybeans (54%). The community structure of leaf-associated bacteria in Nod+ soybeans was almost unaffected by the levels of nitrogen fertilization. However, differences were visible in Nod− and Nod++ soybeans. HN fertilization drastically decreased the relative abundance of Alphaproteobacteria in Nod− and Nod++ soybeans (46% to 76%) and, conversely, increased those of Gammaproteobacteria and Firmicutes in these mutant soybeans. In the Alphaproteobacteria, cluster analyses identified two operational taxonomic units (OTUs) (Aurantimonas sp. and Methylobacterium sp.) that were especially sensitive to nodulation phenotypes under SN fertilization and to nitrogen fertilization levels. Arbuscular mycorrhizal infection was not observed on the root tissues examined, presumably due to the rotation of paddy and upland fields. These results suggest that a subpopulation of leaf-associated bacteria in wild-type Nod+ soybeans is controlled in similar ways through the systemic regulation of autoregulation of nodulation, which interferes with the impacts of N levels on the bacterial community of soybean leaves. PMID:21239540
Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), which is an antagonist to bacterial pathogen (Erwinia amylovora) of fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 µm in diamet...
Full Text Available A chitinolytic bacterial strain having strong antifungal activity was isolated and identified as Burkholderia cepacia MPC-7 based on 16S rRNA gene analysis. MPC-7 solubilized insoluble phosphorous in hydroxyapatite agar media. It produced gluconic acid and 2-ketogluconic acid related to the decrease in pH of broth culture. The antagonist produced benzoic acid (BA and phenylacetic acid (PA. The authentic compounds, BA and PA, showed a broad spectrum of antimicrobial activity against yeast, several bacterial and fungal pathogens in vitro. To demonstrate the biocontrol efficiency of MPC-7 on late blight disease caused by Phytophthora capsici, pepper plants in pot trials were treated with modified medium only (M, M plus zoospore inoculation (MP, MPC-7 cultured broth (B and B plus zoospore inoculation (BP. With the sudden increase in root mortality, plants in MP wilted as early as five days after pathogen inoculation. However, plant in BP did not show any symptom of wilting until five days. Root mortality in BP was markedly reduced for as much as 50%. Plants in B had higher dry weight, P concentration in root, and larger leaf area compared to those in M and MP. These results suggested that B. cepacia MPC-7 should be considered as a candidate for the biological fertilizer as well as antimicrobial agent for pepper plants.
Liao, Lisheng; Zhou, Jianuan; Wang, Huishan; He, Fei; Liu, Shiyin; Jiang, Zide; Chen, Shaohua; Zhang, Lian-Hui
Zeamines (ZMS), a class of polyamine-polyketide-nonribosomal peptide produced by bacterial isolate Dickeya zeae, were shown recently to be potent antibiotics against some bacterial pathogens. In this study, the results indicated that ZMS showed antifungal activity against Peronophythora litchii and other fungal pathogens. The activity of ZMS against the oomycete pathogen P. litchi, which causes the devastating litchi downy blight, was further investigated under in vitro and in vivo conditions...
In Jeong Kang
Full Text Available Burkholderia glumae (bacterial grain rot, Xanthomonas oryzae pv. oryzae (bacterial leaf blight, and Acidovorax avenae subsp. avenae (bacterial brown stripe are major seedborne pathogens of rice. Based on the 16S and 23S rDNA sequences for A. avenae subsp. avenae and B. glumae, and transposase A gene sequence for X. oryzae pv. oryzae, three sets of primers had been designed to produce 402 bp for B. glumae, 490 bp for X. oryzae, and 290 bp for A. avenae subsp. avenae with the 63°C as an optimum annealing temperature. Samples collected from naturally infected fields were detected with two bacteria, B. glumae and A. avenae subsp. avenae but X. oryzae pv. oryzae was not detected. This assay can be used to identify pathogens directly from infected seeds, and will be an effective tool for the identification of the three pathogens in rice plants.
Kang, In Jeong; Kang, Mi-Hyung; Noh, Tae-Hwan; Shim, Hyeong Kwon; Shin, Dong Bum; Heu, Suggi
Burkholderia glumae (bacterial grain rot), Xanthomonas oryzae pv. oryzae (bacterial leaf blight), and Acidovorax avenae subsp. avenae (bacterial brown stripe) are major seedborne pathogens of rice. Based on the 16S and 23S rDNA sequences for A. avenae subsp. avenae and B. glumae , and transposase A gene sequence for X. oryzae pv. oryzae , three sets of primers had been designed to produce 402 bp for B. glumae , 490 bp for X. oryzae , and 290 bp for A. avenae subsp. avenae with the 63°C as an optimum annealing temperature. Samples collected from naturally infected fields were detected with two bacteria, B. glumae and A. avenae subsp. avenae but X. oryzae pv. oryzae was not detected. This assay can be used to identify pathogens directly from infected seeds, and will be an effective tool for the identification of the three pathogens in rice plants.
Teodoro, M.G.; Ferreira, M.A.; Guimarães, L.M.S.; Mafia, R.G.; Groenewald, J.Z.; Crous, P.W.; Alfenas, A.C.
Leaf blight and defoliation caused by Teratosphaeria species is one of the most important leaf diseases of Eucalyptus globulus. Due to the importance of this tree species for the production of pulp and paper, and recent reports of severe leaf disease symptoms in Brazil, the present study was
Juliana Janet R. Martin-Puzon
Full Text Available Objective: To determine the antibacterial activities and the thin-layer chromatography (TLC fingerprint profiles of leaf and stem extracts of Glinus oppositifolius L. Aug. DC (G. oppositifolius. Methods: The leaves and stems were extracted using chloroform, ethanol and methanol as solvents. The antibacterial activity of the extracts were evaluated through disc diffusion, minimum inhibitory concentration and bactericidal concentration assays against methicillinresistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended spectrum β-lactamase-producing, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamaseproducing Pseudomonas aeruginosa (P. aeruginosa and Acinetobacter baumanii (A. baumanii. The TLC separation was carried out on leaf and stem ethanol extracts in ethyl acetate: n-hexane solvent system. Distinct spots were examined under visible light, UV 254 nm, UV 366 nm and after spraying with vanillin-sulfuric acid. Results: The leaf extracts revealed antibacterial activities, inhibiting the growth of the nonresistant and multidrug-resistant strains of the Gram-negative bacteria Escherichia coli, P. aeruginosa and A. baumanii. The TLC fingerprint profiles demonstrated the presence of various phytochemicals in leaf and stem extracts. Leaf extracts exhibited more diverse constituents compared to stem extracts, but some constituents were similar in both plant parts. Conclusions: G. oppositifolius leaf extracts can be used as new, alternative sources of antimicrobials against non-resistant and multidrug-resistant strains of the Gram-negative bacteria Escherichia coli, P. aeruginosa and A. baumanii. The TLC profiles represent the chemical integrity of G. oppositifolius leaf and stem extracts which form an important and powerful tool for standardization, authentication, quality control and determination of bioactive components of G. oppositifolius in any formulation and in powder form.
Romero, Fernando M; Marina, María; Pieckenstain, Fernando L
This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.
Compatibilidade de Dicyma pulvinata com defensivos agrícolas e eficiência do biocontrole do mal-das-folhas da seringueira em campo Compatibility of Dicyma pulvinata with pesticides and biocontrol efficiency of South American leaf blight of rubber tree under field conditions
Débora Ferreira Melo
Full Text Available O objetivo deste trabalho foi avaliar quatro isolados do fungo antagonista Dicyma pulvinata quanto à compatibilidade com defensivos agrícolas e adjuvantes, e a eficiência desses isolados no controle do mal-das-folhas (Microcyclus ulei da seringueira (Hevea sp. em campo. A compatibilidade dos isolados com defensivos e adjuvantes foi avaliada com base no crescimento micelial e na esporulação do fungo, em testes conduzidos in vitro. Para avaliação da eficiência do antagonista contra M. ulei, em campo, os quatros isolados do antagonista foram comparados ao controle exercido pelo tratamento com os fungicidas propiconazol + mancozeb. Os ensaios conduzidos em laboratório indicaram a incompatibilidade de D. pulvinata com os fungicidas benomyl, carbendazim, mancozeb, propiconazol e, ainda, com o inseticida acaricida endosulfan. Dois dos adjuvantes testados (Tween 20 e Tween 80 não afetaram o desenvolvimento do fungo. Foi comprovada a ação do antagonista D. pulvinata sobre M. ulei, em campo, com destaque para os isolados CEN 62 e CEN 93, que apresentaram eficiência de controle semelhante ao tratamento fungicida padrão.The objective of this work was to evaluate four isolates of the antagonist fungus Dicyma pulvinata in terms of its compatibility with chemical pesticides and adjuvants products, and the efficiency of these isolates as biocontrol agent against South American leaf blight (Microcyclus ulei of rubber tree (Hevea sp. under field conditions. Isolates compatibility with chemical pesticides and adjuvants was evaluated on mycelial growth and fungus sporulation in vitro. To assess the efficiency of the antagonist against M. ulei under field conditions, the four isolates were compared to the control by the fungicide mixture propiconazol + mancozeb. The assays showed incompatibility of the antagonistic fungus with the fungicides benomyl, carbendazim, mancozeb, propiconazol, besides the insecticide-acaricide endosulfan. Two of the adjuvants
Tláskal, Vojtěch; Voříšková, Jana; Baldrian, Petr
Roč. 92, č. 11 (2016), fiw177 ISSN 0168-6496 R&D Projects: GA ČR GAP504/12/1288; GA MŠk(CZ) LM2015055 Institutional support: RVO:61388971 Keywords : bacteria * leaf litter * decomposition Subject RIV: EE - Microbiology, Virology Impact factor: 3.720, year: 2016
Bacillus subtilis OH131.1 is a bacterial antagonist of Fusarium graminearum, a plant pathogen which causes Fusarium head blight in wheat. The genome of B. subtilis OH131.1 was sequenced, annotated and analyzed to understand its potential to produce bioactive metabolites. The analysis identified 6 sy...
Jensen Philip J
Full Text Available Abstract Background Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple. The purpose of the present study was to quantify rootstock-mediated differences in scion fire blight susceptibility and to identify transcripts in the scion whose expression levels correlated with this response. Results Rootstock influence on scion fire blight resistance was quantified by inoculating three-year old, orchard-grown apple trees, consisting of 'Gala' scions grafted to a range of rootstocks, with E. amylovora. Disease severity was measured by the extent of shoot necrosis over time. 'Gala' scions grafted to G.30 or MM.111 rootstocks showed the lowest rates of necrosis, while 'Gala' on M.27 and B.9 showed the highest rates of necrosis. 'Gala' scions on M.7, S.4 or M.9F56 had intermediate necrosis rates. Using an apple DNA microarray representing 55,230 unique transcripts, gene expression patterns were compared in healthy, un-inoculated, greenhouse-grown 'Gala' scions on the same series of rootstocks. We identified 690 transcripts whose steady-state expression levels correlated with the degree of fire blight susceptibility of the scion/rootstock combinations. Transcripts known to be differentially expressed during E. amylovora infection were disproportionately represented among these transcripts. A second-generation apple microarray representing 26,000 transcripts was developed and was used to test these correlations in an orchard-grown population of trees segregating for fire blight resistance. Of the 690 transcripts originally identified using the first-generation array, 39 had expression levels that correlated with fire blight resistance in the breeding population. Conclusions Rootstocks had significant effects on the fire blight
80% in both the years against blossom blight disease and their treatments also produced healthy and highest seed yield per plant. Key words: Blossom blight, Colletotrichum capsici, fungicides, Rauvolfia serpentina, sarpagandha.
Canto-Canché, Blondy; Guillén-Maldonado, Diana Karina; Peraza-Echeverría, Leticia; Conde-Ferráez, Laura; James-Kay, Andrew
A bacterial artificial chromosome library of the causal agent of the Black Sigatoka leaf spot disease of banana and plantain, Mycosphaerella fijiensis, has been constructed using a non-sphaeroplasting technique and characterized using both homologous and heterologous probes. After first and a second size selection of PFGE-fractionated DNA, a ligation was obtained using a 1:4 molar ratio (insert:vector). One hundred random clones were analyzed, and the mean insert size was estimated to be 90 kb. The range of the insert sizes was between 40 and 160 kb. The highest percentage of inserts belonged to the range between 80 and 100 kb; 32% of the inserts had 2 or 3 internal NotI sites. This library consists of 1920 clones, if the genomic size is at least 35 Mb, then this represents 4.9 x genome equivalents, which was supported by hybridization results with homologous and heterologous probes.
Prof. Adipala Ekwamu
with resistance against E. turcicum is the most cost-effective way to manage the disease. However there is paucity of information needed to support resistance breeding. The objective of this work was to determine the mode of inheritance of resistance to TLB on sorghum using disease response of segregating lines and.
Breeding for such complex traits is often compounded by genotype by environment interactions and as such, marker assisted selection could hasten the process. Further characterisation of resistance loci and mapping of quantitative trait loci will support effective more resistance breeding. Keywords: Exserohilum turcicum ...
Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage. There is limited published quantitative data on predicting tuber blight. We validated a tuber blight prediction model developed in New York with cultivars Allegany, NY 101, and Katahdin using independent...
... evaluate reactions of different potato genotypes to late blight. There were significant differences among genotypes for tuber yield, late blight readings and earliness. The application of fungicides significantly increased potato yield but had a non significant effect on the damage due to foliage blight (Phytophthora infestans).
Pratheepa, V; Ramesh, S; Sukumaran, N
Aquatic organisms (especially fish) require potent defense mechanisms to protect themselves against pathogen invasion and disease formation. The use of immunostimulants in fish culture can prevent the diseases through augmentation of both specific and non-specific immunity. A study was conducted to investigate the efficacy of different dietary doses of Aegle marmelos (Linn.) Corr. Serr. (Rutaceae) leaf extract for the immune response and the disease resistance of the freshwater fish, Cyprinus carpio Linn. (Cyprinidae) infected by Aeromonas hydrophila Chester (Aeromonadaceae). Hematological, specific immune response, non-specific immune response and enzyme assay studies were performed on fish and were scrutinized after 50 days of feeding trial. Fish were challenged with Aeromonas hydrophila at a dose of 1.5 × 10(4) cells/mL through intraperitoneal injection, and the hematological changes, the immune response, the enzyme activity and the disease resistance of Cyprinus carpio against the pathogen were also studied for 20 days at 5-day intervals. The results obtained from the study demonstrated that the fish fed with leaf extract of Aegle marmelos incorporated into feed significantly enhanced the red blood cell count, white blood cell count, hemoglobin, phagocytic activity, nitroblue tetrazolium chloride assay, lysozyme, pathogen clearance and enzyme activity compared with the control group. The survivability was higher in the fish which consumed leaf extract-incorporated feed, and the fish group fed with 5 g diet showed highest percentage survival of the fish. These results indicate that Aegle marmelos stimulates the immunity and makes the freshwater fish Cyprinus carpio more resistant to Aeromonas hydrophila.
Nagel, Raimund; Turrini, Paula C G; Nett, Ryan S; Leach, Jan E; Verdier, Valérie; Van Sluys, Marie-Anne; Peters, Reuben J
Phytopathogens have developed elaborate mechanisms to attenuate the defense response of their host plants, including convergent evolution of complex pathways for production of the GA phytohormones, which were actually first isolated from the rice fungal pathogen Gibberella fujikuroi. The rice bacterial pathogen Xanthomonas oryzae pv. oryzicola (Xoc) has been demonstrated to contain a biosynthetic operon with cyclases capable of producing the universal GA precursor ent-kaurene. Genetic (knock-out) studies indicate that the derived diterpenoid serves as a virulence factor for this rice leaf streak pathogen, serving to reduce the jasmonic acid-mediated defense response. Here the functions of the remaining genes in the Xoc operon are elucidated and the distribution of the operon in X. oryzae is investigated in over 100 isolates. The Xoc operon leads to production of the bioactive GA 4 , an additional step beyond production of the penultimate precursor GA 9 mediated by the homologous operons recently characterized from rhizobia. Moreover, this GA biosynthetic operon was found to be widespread in Xoc (> 90%), but absent in the other major X. oryzae pathovar. These results indicate selective pressure for production of GA 4 in the distinct lifestyle of Xoc, and the importance of GA to both fungal and bacterial pathogens of rice. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
Adavallan, K; Krishnakumar, N
Gold nanoparticles (Au-NPs) were synthesized at room temperature using Morus alba (mulberry) leaf extract as reducing and stabilizing agent. The development of plant mediated synthesis of nanoparticles is gaining importance due to its simplicity, low cost, non-toxicity, eco-friendliness, long term stability and reproducible aqueous synthesis method to obtain a self-assembly of nearly monodispersed Au-NPs. The formation and morphology of biosynthesized nanoparticles are investigated with the help of UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) techniques. Au-NPs formation was screened by UV-Vis spectroscopy through color conversion due to surface plasmon resonance band at 538 nm for Au-NPs. DLS studies revealed that the average size of Au-NPs was 50 nm. TEM studies showed the particles to be nearly spherical with few irregular shapes and particle size ranges 15−53 nm. The AFM image clearly shows the surface morphology of the well-dispersed Au-NPs with less than 50 nm. The high crystallinity of nanoparticles is evident from bright circular spots in the selected area electron diffraction (SAED) pattern. X-ray diffraction pattern showed high purity and face-centered cubic structure of Au-NPs. The FT-IR results indicate the presence of different functional groups present in the biomolecule capping the nanoparticles. Further, biosynthesized Au-NPs show strong zone of inhibition against Vibrio cholera (gram-negative) and Staphylococcus aureus (gram-positive) whereas, chemically synthesized Au-NPs and mulberry leaf extract exhibit a fair zone of inhibition. (papers)
Verstraete, Brecht; Janssens, Steven; Rønsted, Nina
Every plant species on Earth interacts in some way or another with microorganisms and it is well known that certain forms of symbiosis between different organisms can drive evolution. Within some clades of Rubiaceae (coffee family), a specific plant-bacteria interaction exists in which non......-pathological endo- phytes are present in the leaves of their hosts. It is hypothesized that the bacterial endophytes, either alone or by interacting with the host, provide chemical protection against herbivory or pathogens by pro- ducing toxic or otherwise advantageous secondary metabolites. If the bacteria indeed...... have a direct ben- eficial influence on their hosts, it is reasonable to assume that the endophytes may increase the fitness of their hosts and therefore it is probable that their presence also has an influence on the long-term evolu- tion of the particular plant lineages. In this study, the possible...
Species of Teratosphaeria include some of the most important fungal pathogens of plantation-grown eucalypt trees. During routine disease surveys, symptoms and signs of leaf spot and blight were observed on the foliage of one-year-old E. grandis × E. urophylla hybrids in the Zululand region of KwaZulu-Natal, South Africa ...
Gosal, S.S.; Das, A.; Gopal, J.; Minocha, J.L.; Chopra, H.R.; Dhaliwal, H.S.
In vitro cultured shoots of potato, cvs. 'Kufri Jyoti' and 'Kufri Chandramukhi', were irradiated with 20 and 40 Gy gamma rays. Microtubers, obtained from MIV3 shoots multiplied in vitro, were planted in pots. The resulting plants were screened for resistance to late blight, using detached leaf method. In 'Kufri Chandramukhi', 42% plants and in 'Kufri Jyoti' 36% plants, obtained from 40 Gy treatment, showed resistance to late blight. The frequency of resistant plants was lower from 20 Gy treatment. The progenies of putatively resistant plants were grown in field, and inoculated with sporangial inoculum of late blight fungus. The field grown progeny segregated for disease resistance, and approximately 56% plants showed resistance. During the next propagation, the frequency of resistant plants increased to 72%. For developing heat tolerance, microtubers obtained from 20 and 40 Gy treatments and in vitro multiplied M 1 V 3 shoots were cultured at high temperature of 28C. In both varieties, the number of the microtubers per plant was highly reduced and the resulting microtubers had distorted shape but showed better germination (62%), even in early sowing at relatively higher temperature. Of the two radiation doses, the higher dose of 40 Gy gave better results in both the varieties. Heat tolerance was also assessed from chlorophyll persistence. The progenies from putative heat-tolerant plants were tested in field by planting at higher temperature in two subsequent generations. The heat tolerant plants segregated in each generation, but the frequency of heat-tolerant plants increased. (author)
Vieira, R A; Scapim, C A; Moterle, L M; Tessmann, D J; Conrado, T V; Amaral Júnior, A T
We estimated general and specific combining abilities and examined resistance to northern leaf blight (Exserohilum turcicum) and to gray leaf spot (Cercospora zeae-maydis) in a set of nine inbred popcorn lines. These inbreds were crossed in a complete diallel scheme without reciprocals, which produced 36 F(1) hybrids. Two experiments with a square lattice design and three replications were conducted during the 2008/2009 crop season, in Maringá, PR, Brazil. The severity of northern leaf blight and gray leaf spot was assessed under natural infestation conditions. Data were examined by individual and joint analysis of variance. Individual and joint Griffing's diallel analyses were carried out for adjusted means. General combining ability and specific combining ability were significant (P < 0.10) by the F-test for northern leaf blight and gray leaf spot infestation levels. This denotes that additive and non-additive gene effects both contributed to resistance to these diseases, but that the additive gene effects were more important. Among the inbred lines, P(8) and P(9) gave the highest resistance to northern leaf blight, and P(3) and P(4.3) gave the highest resistance to gray leaf spot. The hybrids P(7.4) x P(8) and P(4.3) x P(9) could be exploited by reciprocal recurrent selection to provide genotypes with both northern leaf blight and gray leaf spot resistance. Significant interaction between general combining ability and crop season (P < 0.10) denotes the importance of environment, even though the disease levels in the hybrids were quite consistent.
Full Text Available Objective: To investigate the antimicrobial activity and phytochemical screening Ethanol, methanol, Ethyl acetate, acetone, chloroform, Petroleum ether, hexane, hot water, and extracts of Carica papaya. Methods: The aim of the present study was to evaluate the qualitative analysis of phytochemicals and antimicrobial activity of various solvent extracts of Carica papaya. The antimicrobial activities of different solvent extracts of Carica papaya were tested against the Gram-positive and Gram-negative bacterial strains and fungus by observing the zone of inhibition. The Gram-positive bacteria used in the test were Staphylococcus aureus, Bacillus cereus and Micrococcus luteus, and the Gram-negative bacteria were Escherichia coli, and Klebsiella pneumoniae, fungus like Aspergillus niger, Aspergillus flavus, Candida albicans, Candida tropicalis, Cryptococcus neoformans, and Candida kefyr. Results: It was observed that ethanol, methanol, ethyl acetate, aceton, chloroform, petroleum ether, hexane and aquas extracts showed activity against bacteria and fungus. The chloroform extract of Carica papaya showed more activity against Micrococcus luteus, zone of diameter 15.17暲0.29mm and acetone extract of Carica papaya showed more activity against Candida albicans, zone of diameter 11.23暲0.25mm compared to other solvent extracts. Conclusions: In this study chloroform extract in bacteria and acetone extract in fungus showed a varying degree of inhibition to the growth of tested organism, than Ethanol, methanol, Ethyl acetate, Petroleum ether, hexane and hot water extracts. The results confirmed the presence of antibacterial and antifungal activity of Carica papaya extract against various human pathogenic bacteria. Presences of phytochemical and antimicrobial activity are confirmed.
Palazzini, Juan M.; Alberione, Enrique; Torres, Adriana; Donat, Christina; Kohl, Jurgen; Chulze, Sofia
Fusarium head blight (FHB) mainly caused by Fusarium graminearum is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. The biocontrol effect of two bacterial strains on FHB incidence, severity and deoxynivalenol (DON)
Full Text Available Potato (Solanum tuberosum L. has been remained an important agricultural crop in resolving global food issues through decades. The crop has experienced enormous growth in terms of production throughout the world in recent decades because of improvement in agricultural mechanization, fertilizers application and irrigation practices. Nevertheless, a significant proportion of this valuable crop is still vulnerable to losses due to prevalence of different viral, bacterial, fungal and nematodes infestations. Late blight, caused by Phytophthora infestans (Mont. de Bary, is one of the most threatening pathogenic diseases which not only results in direct crop losses but also cause farmers to embrace huge monetary expenses for disease control and preventive measures. The disease is well known for notorious ‘Irish Famine’ which resulted in drop of Irish population by more than 20% as result of hunger and potato starvation. Globally, annual losses of crop and money spend on fungicides for late blight control exceeds one trillion US dollars. This paper reviews the significance of late blight of potato and controlling strategies adopted for minimizing yield losses incurred by this disease by the use of synthetic fungicides. Advantages and disadvantages of fungicides application are discussed.
Significant reciprocal effects indicate the importance of maternal contribution in controlling the BLB virulence. For this, resistant lines can be used as female parents for fear of affecting transfer of resistance to the progenies, and the hybrids and their reciprocals would be handled separately. Low estimates of narrow sense ...
Prof. Adipala Ekwamu
choice of parents for this trait. Low heritability estimates highlight the important influence of non-additive gene action in the expression of the resistance to the BLB in rice, which implies selection of the best lines at later generations to allow fixation of maximum homozygosity. ACKNOWLEDGEMENT. The financial support of ...
Prof. Adipala Ekwamu
Pastor-Corrales, 1991; Zapata et al., 2009; 2010). Quantitative inheritance was observed by Honna. (1956) after making original interspecific crosses between resistant P. acutifolius 'tepary 4' and susceptible P. vulgaris. It is also critical to have durable sources of resistance to Xap. Sources of resistance to Xap in common ...
Jul 26, 2012 ... legumes and is a pathogen hard to control (Zanatta et al.,. 2007). Increasing resistance of pathogen and detrimental effect of chemicals force us to search an alternative for better disease management.Of the different management strategies, biocontrol of the pathogens by plant growth promoting bacteria ...
Golas, T.M.; Weerden, van der G.M.; Berg, van den R.G.; Mariani, C.; Allefs, J.J.H.M.
Four sites with naturally growing Solanum dulcamara were surveyed during 2006 and 2007 for the presence of late blight. Despite 2 years of observations, no late blight was detected among natural populations of bittersweet. Nevertheless, repeated infections occurred on few S. dulcamara plants from a
The tomato late blight pandemic of 2009 made late blight into a household term in much of the eastern United States. Many home gardeners and organic producers lost most, if not all, of their tomato crop, and their experiences were reported in the mainstream press. This article, which is written for ...
Crop and soil management may modify canopy and below ground microclimate; however, their effects on potential development and control of early and late blight are not well documented. Crop management systems (Status Quo (SQ), Soil Conserving (SC), Soil Improving (SI), Disease Suppressive (DS), and c...
Xie, Chuanqi; Shao, Yongni; Li, Xiaoli; He, Yong
This study investigated the potential of using hyperspectral imaging for detecting different diseases on tomato leaves. One hundred and twenty healthy, one hundred and twenty early blight and seventy late blight diseased leaves were selected to obtain hyperspectral images covering spectral wavelengths from 380 to 1023 nm. An extreme learning machine (ELM) classifier model was established based on full wavelengths. Successive projections algorithm (SPA) was used to identify the most important wavelengths. Based on the five selected wavelengths (442, 508, 573, 696 and 715 nm), an ELM model was re-established. Then, eight texture features (mean, variance, homogeneity, contrast, dissimilarity, entropy, second moment and correlation) based on gray level co-occurrence matrix (GLCM) at the five effective wavelengths were extracted to establish detection models. Among the models which were established based on spectral information, all performed excellently with the overall classification accuracy ranging from 97.1% to 100% in testing sets. Among the eight texture features, dissimilarity, second moment and entropy carried most of the effective information with the classification accuracy of 71.8%, 70.9% and 69.9% in the ELM models. The results demonstrated that hyperspectral imaging has the potential as a non-invasive method to identify early blight and late blight diseases on tomato leaves. PMID:26572857
Nov 16, 2009 ... DNA (cDNA) clones; automated sequencing techniques ... stranded cDNA. Lane 1: double-strand cDNA; lane. M: DL2000 marker. the recombinants and determined the percentage of recombinant clones, 16 plaques were randomly picked from plate. .... 1.00E-45 blight-associated protein p12 precursor. 2.
A. P. Viégas
Full Text Available Em Campinas, a Seca do mangueira (Mangifera indica L. é causada pelo fungo Ceratostomella fimbriata, associado a Hypothenemus plumeriae, broca semelhante à do café, O inseto abre furos nos tecidos sadios e pode levor ou não o patógeno. Quando o potógeno é levado às partes mais verdes, suculentas de mangueira, a murcha ocorre cerca de 10-15 dias após, e os tecidos recentemente mortos são colonizados por Hypothenemus plumeriae. A moléstia parece ser idêntica ao "Mal do Recife".Mango-blight in Campinas is caused by Ceratostomella fimbriata. When green parts of branches of healthy mango plants were inoculated with cultures of the tungus, blight appeared after 10-15 days and the rotten tissues were colonized by Hypothenemus plumeriae, an insect closely related to the caffee-borer. The insect may or may not be a vector of the disease when opening galleries in healthy branches. The disease seems to be identical to the "mal do Recife" (4. Perithecia are produced in diseased tissues. Asei of the fungus are provided with a delicate, evanescent wall. There is no endogenous wall in the asci as claimed by Andrus and Harrer (2. Protoperithecia when crushed under a cover-slip in a drop of eosin show eosinophil asci with a clear cut wall, and four 2-septate ascospores.
Maeda, Satoru; Hayashi, Nagao; Sasaya, Takahide; Mori, Masaki
Broad-spectrum disease resistance against two or more types of pathogen species is desirable for crop improvement. In rice, Xanthomonas oryzae pv. oryzae (Xoo), the causal bacteria of rice leaf blight, and Magnaporthe oryzae, the fungal pathogen causing rice blast, are two of the most devastating pathogens. We identified the rice BROAD-SPECTRUM RESISTANCE 1 (BSR1) gene for a BIK1-like receptor-like cytoplasmic kinase using the FOX hunting system, and demonstrated that BSR1-overexpressing (OX) rice showed strong resistance to the bacterial pathogen, Xoo and the fungal pathogen, M. oryzae. Here, we report that BSR1-OX rice showed extended resistance against two other different races of Xoo, and to at least one other race of M. oryzae. In addition, the rice showed resistance to another bacterial species, Burkholderia glumae, which causes bacterial seedling rot and bacterial grain rot, and to Cochliobolus miyabeanus, another fungal species causing brown spot. Furthermore, BSR1-OX rice showed slight resistance to rice stripe disease, a major viral disease caused by rice stripe virus. Thus, we demonstrated that BSR1-OX rice shows remarkable broad-spectrum resistance to at least two major bacterial species and two major fungal species, and slight resistance to one viral pathogen.
Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok
We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05) reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05) reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit. PMID:25288942
Mee Kyung Sang
Full Text Available We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107 among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P < 0.05 reduced Phytophthora blight without influencing rhizosphere microbial populations; they showed similar or better levels of disease suppressions than in metalaxyl treatment in the 2007 and 2009 tests, but not in the 2008 test. In the 2-year plastic house tests, all the selected strains significantly (P < 0.05 reduced anthracnose incidence in at least one of the test years, but their biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.
Novisel Veitía; Lourdes R. García; Idalmis Bermúdez-Caraballoso; Mayra Acosta- Suárez; Michel Leiva-Mora; Damaris Torres; Carlos Romero; Pedro Orellana
Six potato clones, selected in vitro for their resistance to Alternaria solani Sor. culture filtrates, were evaluated for their field response to early blight infection. Field screening were performance under artificial inoculation and natural conditions. Early blight response was evaluated based on lesion size, disease severity, and area under disease progress curve (AUDPC). One clone displayed reduced lesion area (0.35 cm2) and AUDPC values compared to cv. `Desirée' (susceptible control) (0...
Saleem, M.Y.; Asghar, M.; Khan, A.R.; Iqbal, Q.
Genetic control of late blight (LB) and some economic traits was assessed to identify genotypes suitable for the hybrids were derived from crossing of 2 male sterile lines viz., development of late blight resistant hybrids in tomato. 10 F/sub 1/ hybrid were derived from crossing of 2 male sterile lines viz., TMS1 and TMS2 with 5 elite lines viz., Nagina, Riogrande, Roma, 88572 and Picdenato according to line x tester technique. Disease resistance was measured using detached leaf and whole plant assay techniques. Data were also recorded for days to maturity, number of fruit per plant, single fruit weight and yield per plant. The analysis of variance showed significant differences among crosses, lines, testers and line x tester interaction for almost all parameters. Estimate of genetic components indicated preponderance of additive type of gene action for detached leaf assay, whole plant assay, number of fruit per plant and yield per plant whereas non-additive type of gene action for days to maturity and single fruit weight. Among parents, TMS2, Nagina, Roma and Picdenato showed significant favorable general combing ability (GCA) effects for disease rating traits while TMS1 and Riogrande indicated desirable GCA effects for yield and some yield related traits. Among hybrids, TMS2 x Roma and TMS1 x Riogrande had significant specific combing ability (SCA) effects for detached and whole plant assays. However, hybrid TMS2 x Roma appeared as good combination of LB resistance as it had both parents with desirable GCA effects. All hybrids showed average type of SCA effects for yield and yield components. Genetic control of LB revealed that a multiple crossing program involving genotypes with high GCA effects would be rewarding to identify LB resistant genotypes in early generations. (author)
Full Text Available Taro leaf blight (caused by the Oomycete Phytophthora colocasiae is a disease of major importance in many regions of the world where taro is grown. Serious outbreaks of taro leaf blight in Samoa in 1993 and in the last few years in Cameroon, Ghana and Nigeria continue to demonstrate the devastating impact of this disease on the livelihoods and food security of small farmers and rural communities dependent on the crop. The spread of the disease to new geographical areas also poses a major threat to neighbouring countries and taro growing regions still free from the disease. Past research, particularly in the Pacific, has demonstrated that management measures such as chemical and cultural control are largely ineffective and that breeding for disease resistance is the most sustainable approach to manage the disease. Recently, the Pacific and South-east Asian regional taro networks have made excellent progress in developing cultivars resistant to taro leaf blight through enhanced utilization of taro genetic resources and close collaboration between farmers and researchers in breeding programs. These programs have secured vital taro genetic resources for future use. This paper provides an overview of the disease, its origin, distribution, biology, epidemiology, management and global impact. The paper will largely focus on breeding strategies to address the disease including challenges, opportunities and constraints. It also discusses how these breeding experiences and outputs can be scaled up to other geographical areas where the disease has been recently introduced or under threat of introduction.
Gun Woong Lee
Full Text Available Phytophthora blight and anthracnose disease caused by Phytophthora capsici and Collectotrichum gloeosporioides are the most important devastating diseases of red pepper plants, worldwide. Five different bacterial isolates were isolated from the red pepper rhizosphere and non-rhizosphere soil and subsequently tested for antagonistic activity against P. capsisi and C. gloeosporioides. The area of the inhibition zone was taken as a measure for antagonistic activity. Among the 5 isolates tested, S54 exhibited a maximum antagonistic activity under in vitro and in vivo conditions. In greenhouse studies the isolate has successfully reduced the disease symptom. Protect value was 80.8% (Phytophthora blight and 81.9% (Anthrancnose disease, whereas the infection rate of control plants was 21.3% and 23.2%. Based on the 16S rDNA sequence and API 50CHB Kit analysis the most effective isolate was identified as Bacillus subtilis. The results of the study indicate that the stratin S54 could be used as an potential biological control of Phytophthora blight and anthracnose disease of red pepper.
Background Breeding of fire blight resistant scions and rootstocks is a goal of several international apple breeding programs, as options are limited for management of this destructive disease caused by the bacterial pathogen Erwinia amylovora. A broad, large-effect quantitative trait locus (QTL) for fire blight resistance has been reported on linkage group 3 of Malus ‘Robusta 5’. In this study we identified markers derived from putative fire blight resistance genes associated with the QTL by integrating further genetic mapping studies with bioinformatics analysis of transcript profiling data and genome sequence databases. Results When several defined E.amylovora strains were used to inoculate three progenies from international breeding programs, all with ‘Robusta 5’ as a common parent, two distinct QTLs were detected on linkage group 3, where only one had previously been mapped. In the New Zealand ‘Malling 9’ X ‘Robusta 5’ population inoculated with E. amylovora ICMP11176, the proximal QTL co-located with SNP markers derived from a leucine-rich repeat, receptor-like protein ( MxdRLP1) and a closely linked class 3 peroxidase gene. While the QTL detected in the German ‘Idared’ X ‘Robusta 5’ population inoculated with E. amylovora strains Ea222_JKI or ICMP11176 was approximately 6 cM distal to this, directly below a SNP marker derived from a heat shock 90 family protein gene ( HSP90). In the US ‘Otawa3’ X ‘Robusta5’ population inoculated with E. amylovora strains Ea273 or E2002a, the position of the LOD score peak on linkage group 3 was dependent upon the pathogen strains used for inoculation. One of the five MxdRLP1 alleles identified in fire blight resistant and susceptible cultivars was genetically associated with resistance and used to develop a high resolution melting PCR marker. A resistance QTL detected on linkage group 7 of the US population co-located with another HSP90 gene-family member and a WRKY transcription factor
Gardiner Susan E
Full Text Available Abstract Background Breeding of fire blight resistant scions and rootstocks is a goal of several international apple breeding programs, as options are limited for management of this destructive disease caused by the bacterial pathogen Erwinia amylovora. A broad, large-effect quantitative trait locus (QTL for fire blight resistance has been reported on linkage group 3 of Malus ‘Robusta 5’. In this study we identified markers derived from putative fire blight resistance genes associated with the QTL by integrating further genetic mapping studies with bioinformatics analysis of transcript profiling data and genome sequence databases. Results When several defined E.amylovora strains were used to inoculate three progenies from international breeding programs, all with ‘Robusta 5’ as a common parent, two distinct QTLs were detected on linkage group 3, where only one had previously been mapped. In the New Zealand ‘Malling 9’ X ‘Robusta 5’ population inoculated with E. amylovora ICMP11176, the proximal QTL co-located with SNP markers derived from a leucine-rich repeat, receptor-like protein ( MxdRLP1 and a closely linked class 3 peroxidase gene. While the QTL detected in the German ‘Idared’ X ‘Robusta 5’ population inoculated with E. amylovora strains Ea222_JKI or ICMP11176 was approximately 6 cM distal to this, directly below a SNP marker derived from a heat shock 90 family protein gene ( HSP90. In the US ‘Otawa3’ X ‘Robusta5’ population inoculated with E. amylovora strains Ea273 or E2002a, the position of the LOD score peak on linkage group 3 was dependent upon the pathogen strains used for inoculation. One of the five MxdRLP1 alleles identified in fire blight resistant and susceptible cultivars was genetically associated with resistance and used to develop a high resolution melting PCR marker. A resistance QTL detected on linkage group 7 of the US population co-located with another HSP90 gene-family member and a WRKY
Full Text Available Background: Anembryonic gestation (blighted ovum is the most common identifiable pathology in the first trimester of pregnancy, always leads to miscarriage. Early pregnancy failures from blighted ovum are often due to chromosomal abnormalities and a poor quality of sperm or egg. Oxidative stresses as a factor of disturbance balance between the production of free radicals and antioxidant defenses is involved in the pathogenesis of many diseases, including mouth and throat cancer and cardiovascular disease. Catalase is one of the defensive systems against damages caused by oxidative stress in human. The aim of this study was to compare the activity of salivary catalase in women with blighted ovum and women with history of normal pregnancy. Methods: This case-control study was performed on 34 patient women with blighted ovum and 34 healthy women as a control group. The study was performed in biochemistry laboratory at the University of Guilan from October 2015 to July 2015. The age range was 20-44 years and 18-45 years in patient and control groups, respectively. Unstimulated saliva samples were collected using spitting method. Catalase activity was measured by evaluating the constant rate of hydrogen peroxide decomposition in patient and control groups. Results: The patient group matched with healthy subjects in average age and having no other diseases history. The biochemical enzymatic assays indicate that the average catalase activities of saliva in patient and control groups were 14.47±3.8 and 16.42±3.48, respectively. Therefore, the catalase activity was significantly reduced in patient group as compared to the control group (P=0.03. Conclusion: The obtained results suggested that oxidative stress plays an important role in the pathogenesis of blighted ovum. Therefore, determination the activity of other antioxidant enzymes, in addition to catalse, may be used as a marker for diagnosis of blighted ovum. More studies with larger studied
Guan, Wei; Shao, Jonathan; Singh, Raghuwinder; Davis, Robert E; Zhao, Tingchang; Huang, Qi
A TaqMan-based real-time PCR assay was developed for specific detection of strains of X. fastidiosa causing oleander leaf scorch. The assay uses primers WG-OLS-F1 and WG-OLS-R1 and the fluorescent probe WG-OLS-P1, designed based on unique sequences found only in the genome of oleander strain Ann1. The assay is specific, allowing detection of only oleander-infecting strains, not other strains of X. fastidiosa nor other plant-associated bacteria tested. The assay is also sensitive, with a detection limit of 10.4fg DNA of X. fastidiosa per reaction in vitro and in planta. The assay can also be applied to detect low numbers of X. fastidiosa in insect samples, or further developed into a multiplex real-time PCR assay to simultaneously detect and distinguish diverse strains of X. fastidiosa that may occupy the same hosts or insect vectors. Specific and sensitive detection and quantification of oleander strains of X. fastidiosa should be useful for disease diagnosis, epidemiological studies, management of oleander leaf scorch disease, and resistance screening for oleander shrubs. Published by Elsevier B.V.
May 1, 2013 ... Marker assisted selection of bacterial blight resistance genes in rice. Biochem Genet. 39 (7): 261-278. Du PV, Loan, LC, Sang ND (2007). Blast research in Mekong river delta of Vietnam. In: JIRCAS (Japan International Research Center for Agricultural Sciences, Tsukuba, Japan) working report No. 53,.
José Gilberto Sousa Medeiros
Full Text Available Bacterial leaf spot (BLS, caused by Xanthomonas arboricola pv. pruni, is one of the most important diseases in Brazilian peach [Prunus persica (L. Batsch] orchards and all over the world. The main objective of this study was to evaluate for BLS sensitivity of peach genotypes. Evaluations of thirty genotypes were carried out during the onset of the disease, for incidence, severity and defoliation, in field conditions. Pearson's correlations between the percentage of defoliation and leaf severity rating were performed. Genotypes 'Conserva 985', 'Conserva 871', 'Conserva 1129', and 'Tropic Snow', as resistance sources, and 'Conserva 1153', 'Bonão', 'Conserva 1125', and 'Atenas', as susceptible to BLS, were submitted to detached-leaf bioassay and greenhouse evaluation. The peach genotypes showed different reactions to the BLS, and none was immune to the pathogen. 'Conserva 985' and 'Conserva 1129' confirmed resistance responsiveness while 'Conserva 1153', 'Conserva 1125' and 'Atenas' were found susceptible for the detached-leaf bioassay.A bacteriose foliar causada por Xanthomonas arboricola pv. pruni é uma das mais importantes doenças do pessegueiro [Prunus persica (L. Batsch] no Brasil e no mundo. Avaliou-se a sensibilidade de genótipos de pessegueiro a X. arboricola pv. pruni. Trinta genótipos foram avaliados em campo, quanto à incidência, severidade e desfolha causada pela bactéria. Calculou-se a correlação entre desfolha e severidade da doença. A partir dos resultados obtidos em campo, foram selecionados quatro genótipos resistentes ('Conserva 985', 'Conserva 871', 'Conserva 1129' e 'Tropic Snow' e quatro suscetíveis ('Conserva 1153', 'Bonão', 'Conserva 1125' e 'Atenas' para serem novamente avaliados pelo bioensáio com folhas destacadas e em casa de vegetação. Os genótipos diferiram quanto a reação ao patógeno, não sendo observada imunidade. Confirmou-se a resistência para 'Conserva 985' e 'Conserva 1129' e a
Wang, Lu-Yao; Xie, Yue-Shen; Cui, Yuan-Yu; Xu, Jianjun; He, Wei; Chen, Huai-Gu; Guo, Jian-Hua
Fusarium root-rot and fusarium head blight are plant diseases caused by Fusarium sp. in different growth periods of wheat, bring heavy losses to crop production in China. This research is aiming to screen biocontrol agents conjunctively for controlling these two diseases at the same time, as well as evaluate our previous BCAs (Biological Control Agents) screening strategies in more complex situation, considering biocontrol is well concerned as an environmental-friendly plant disease controlling method. Totally 966 bacterial isolates were screened from different parts of wheat tissues, of which potential biocontrol values were detected according to their abilities in antagonism inhibition and secreting extracellular hydrolytic enzyme. Biocontrol tests against fusarium root rot and fusarium head blight were carried out on 37 bacterial isolates with potential biocontrol capacity after pre-selection through ARDRA- and BOX-PCR analysis on strains with high assessment points. We acquired 10 BCAs with obvious biocontrol efficacy (more than 40%) in greenhouse and field tests. Pseudomonas fluorescens LY1-8 performed well in both two tests (biocontrol efficacy: 44.62% and 58.31%), respectively. Overall, correlation coefficient is 0.720 between assessment values of 37 tested BCA strains and their biocontrol efficacy in trails against fusarium root rot; correlation coefficient is 0.806 between their assessment values and biocontrol efficacy in trails against fusarium head blight. We acquired 10 well-performed potential BCAs, especially P. fluorescens LY1-8 displayed good biocontrol capacity against two different diseases on wheat. Biocontrol efficacies results in both greenhouse and field tests showed high positive correlation with assessment values (0.720 and 0.806), suggesting that the BCAs screening and assessing strategy previously developed in our lab is also adaptable for conjunctively screening BCAs for controlling both root and shoot diseases on wheat caused by same
Jun 30, 2015 ... 1 Department of Plant and Applied Botany Federal University of Agriculture, Abeokuta Ogun state Nigeria. email@example.com. 2 Department of Plant and Applied Botany. .... Institute London. PP 12-13. Mew T W, 1987. Current status and future prospects of research on bacterial blight of rice. Ann.
IMPACT OF FUNGICIDE APPLICATIONS FOR LATE BLIGHT. MANAGEMENT ON HUCKLEBERRY YIELDS IN CAMEROON. D. A. FONTEM, A.T. SONGWALANG, J.E. BERINYUY and R.R. SCHIPPERS l. Faculty of Agriculture, University of Dschang, Box 208, Dschang, Cameroon l~orticultural Development Services LLP, ...
Tomato (Solanum lycopersicum L.) production in Tanzania is affected by late blight disease caused by Phytophthora infestans (Mont.) de Bary. Currently, farmers spray more than 12 per crop per season to control diseases by weekly spraying. Field experiments were conducted at Morogoro to evaluate the performance of ...
Halo blight caused by (Pseudomonas syringe pv. phaseolicola (Burkh) (Psp)) is an important disease of common bean (Phaseolus vulgaris L.) world-wide. Several races of the Psp exist and likewise some sources of resistance in common bean have been identified. CAL 143, is a CIAT-bred common bean line, which was ...
Cooke, R.J.; Schepers, H.T.A.M.; Hermansen, A.; Bain, R.; Bradshaw, N.; Ritchie, F.; Shaw, D.S.; Evenhuis, A.; Kessel, G.J.T.; Wander, J.G.N.; Andersson, B.; Hansen, J.G.; Hannukkala, A.; Naerstad, R.; Nielsen, B.
Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe. Before 1980, the worldwide population of P. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single
LeBlanc, Nicholas; Salgado-Salazar, Catalina; Crouch, Jo Anne
Boxwood blight is an emerging disease of ornamental and native boxwood plants in the family Buxaceae. First documented in the 1990s at a single location in England, the disease is now reported throughout Europe, Asia, New Zealand, and North America. To address the growing concern over boxwood blight, ongoing research focuses on multiple biological and genetic aspects of the causal pathogens and susceptible host plants. Characterization of genetic variation among the Calonectria fungi that cause boxwood blight shows that two unique sister species with different geographic distributions incite the disease. Studies of the pathogen life cycle show the formation of long-lived survival structures and that host infection is dependent on inoculum density, temperature, and humidity. Host range investigations detail high levels of susceptibility among boxwood as well as the potential for asymptomatic boxwood infection and for other plants in the family Buxaceae to serve as additional hosts. Multiple DNA-based diagnostic assays are available, ranging from probe-based quantitative PCR assays to the use of comparative genomics to develop robust diagnostic markers or provide whole genome-scale identifications. Though many questions remain, the research that continues to address boxwood blight demonstrates the importance of applying a multidisciplinary approach to understand and control emerging plant diseases.
Jan 3, 2012 ... Potato early blight disease caused by Alternaria solani is one of the major factors limiting potato production worldwide. Developing highly resistant cultivars is the most effective way to control the disease. In this study, 20 random amplified polymorphic DNA (RAPD) and 6 simple sequence repeats.
In this study, 20 random amplified polymorphic DNA (RAPD) and 6 simple sequence repeats (SSR) primers were applied to assess the genetic diversity and to identify molecular markers associated with resistance to early blight disease in resistant (Cara, Spunta and Valor), moderately resistant (Hermes and Atlantic) and ...
This study evaluated the effect of two plant extracts, Ricinus communis and Chromolaena odorata on the control of the early blight pathogen, Alternaria solani (Ell. and Mart.). The study was conducted in the Laboratory of the Crop Production and Horticulture Department, Federal University of Technology, Yola, Adamawa ...
Fusarium graminearum (Fg), the primary fungal pathogen responsible for Fusarium head blight (FHB), reduces crop yield and contaminates grain with trichothecene mycotoxins that are deleterious to plant, human and animal health. In this presentation, we will discuss two different research projects tha...
Esther Ortíz de Urbina
Full Text Available Red band needle blight caused by Dothistroma septosporum and D. pini, and brown spot needle blight caused by Lecanosticta acicola provoke severe and premature defoliation in Pinus, and subsequent reduction of photosynthetic surfaces, vitality, and growth in young and adult trees. The recurrent damage results in branch and tree death. Until recently, pine needle blight diseases have had only minor impacts on native and exotic forest trees in the North of Spain, but in the past five years, these pathogen species have spread widely and caused severe defoliation and mortality in exotic and native plantations of Pinus in locations where they were not detected before. In an attempt to understand the main causes of this outbreak and to define the effectiveness of owners’ management strategies, four research actions were implemented: a survey of the management activities implemented by the owners to reduce disease impact, the evaluation of specific symptoms and damage associated with infection, and the identification of the causative pathogenic species and their reproductive capacity. Morphological characteristics of the fungus and molecular identification were consistent with those of Lecanosticta acicola and Dothistroma spp., D. septosporum, D. Pini, and both mating types were present for the three identified pathogens. The local silvicultural management performed, mainly pruning and thinning, was not resulting in the expected improvement. The results of this study can be applied to establish guidelines for monitoring and controlling the spread of needle blight pathogens.
The influence of late blight infections, caused by Phytophthora infestans, was evaluated on thirteen huckleberry (Solanum scabrum) varieties during the 2000 and 2001 cropping seasons in Dschang, Cameroon. A randomised split block design was used. Plants were sprayed four times with Ridomil Plus® (12% metalaxyl + ...
Full Text Available Six potato clones, selected in vitro for their resistance to Alternaria solani Sor. culture filtrates, were evaluated for their field response to early blight infection. Field screening were performance under artificial inoculation and natural conditions. Early blight response was evaluated based on lesion size, disease severity, and area under disease progress curve (AUDPC. One clone displayed reduced lesion area (0.35 cm2 and AUDPC values compared to cv. `Desirée' (susceptible control (0.58 cm2 but those values were higher than that of the resistant control Solanum chacoense `PI 275136' (0.14 cm2. On the other hand, no differences in lesion number were detected between the susceptible control and the selected clones. This variable showed values between 21.82 and 23.87 lesions in two leaves per plant. Although early blight resistance in potato is generally associated to late maturity, the mutant IBP-27 displayed increased resistance to early blight with medium-late maturity. The six clones presented medium-early to medium-late maturity, similar to parental cv. `Desirée' (vegetative cycle ranging from 90 to 110 days. One clone was found to have higher levels of resistant to early blight than cv. `Desirée' but lower than the levels of the resistant control S. chacoense. The resistance in this clone was characterized by the reduction in lesion area, disease severity, and AUDPC values in both artificial inoculation and natural infection screening. Keywords: Alternaria solani,components of resistance, Solanum tuberosum
Thiele, K; Smalla, K; Kropf, S; Rabenstein, F
The black leaf spot disease on corn salad caused by the bacterium Acidovorax valerianellae has been observed in Europe for several years and causes economic losses in corn salad cropping. Contaminated seeds or infested soil are considered as the major infection sources. The use of healthy seed material is the only way to prevent disease outbreaks. Therefore, a sensitive diagnostic method for seed testing should be developed. Using a triple antibody sandwich ELISA with a high-specific monoclonal antibody, a quick and reliable detection method for contamination of seed lots with the pathogen was developed. This method allowed to detect contaminated seed lots as well as contamination with A. valerianellae in single seeds. Furthermore, the occurrence and distribution of the pathogen could be shown in symptomatic corn salad leaves and in naturally infested seeds by transmission electron microscopy and immunogold labelling for the first time. Our results confirm the seed transmission of this corn salad disease. Pathogen load and distribution vary between positively tested seed lots. With this method, not only routine testing of seed material to eliminate contaminated seed lots from production is possible but also the control of sanitation procedures to reduce contamination. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.
Merali, Zara; Mayer, Melinda J; Parker, Mary L; Michael, Anthony J; Smith, Andrew C; Waldron, Keith W
Tobacco plants (Nicotiana tabacum cv XHFD 8) were genetically modified to express a bacterial 4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL) enzyme which is active with intermediates of the phenylpropanoid pathway. We have previously shown that HCHL expression in tobacco stem resulted in various pleiotropic effects, indicative of a reduction in the carbon flux through the phenylpropanoid pathway, accompanied by an abnormal phenotype. Here, we report that in addition to the reduction in lignin and phenolic biosynthesis, HCHL expression also resulted in several gross morphological changes in poorly lignified tissue, such as abnormal mesophyll and palisade. The effect of HCHL expression was also noted in lignin-free single cells, with suspension cultures displaying an altered shape and different growth patterns. Poorly/non-lignified cell walls also exhibited a greater ease of alkaline extractability of simple phenolics and increased levels of incorporation of vanillin and vanillic acid. However, HCHL expression had no significant effect on the cell wall carbohydrate chemistry of these tissues. Evidence from this study suggests that changes in the transgenic lines result from a reduction in phenolic intermediates which have an essential role in maintaining structural integrity of low-lignin or lignin-deprived cell walls. These results emphasize the importance of the intermediates and products of phenylpropanoid pathway in modulating aspects of normal growth and development of tobacco. Analysis of these transgenic plants also shows the plasticity of the lignification process and reveals the potential to bioengineer plants with reduced phenolics (without deleterious effects) which could enhance the bioconversion of lignocellulose for industrial applications. Copyright © Physiologia Plantarum 2012.
Sang, Mee Kyung; Shrestha, Anupama; Kim, Du-Yeon; Park, Kyungseok; Pak, Chun Ho; Kim, Ki Deok
We previously developed a sequential screening procedure to select antagonistic bacterial strains against Phytophthora capsici in pepper plants. In this study, we used a modified screening procedure to select effective biocontrol strains against P. capsici; we evaluated the effect of selected strains on Phytophthora blight and anthracnose occurrence and fruit yield in pepper plants under field and plastic house conditions from 2007 to 2009. We selected four potential biocontrol strains (Pseudomonas otitidis YJR27, P. putida YJR92, Tsukamurella tyrosinosolvens YJR102, and Novosphingobium capsulatum YJR107) among 239 bacterial strains. In the 3-year field tests, all the selected strains significantly (P biocontrol activities were variable. In addition, strains YJR27, YJR92, and YJR102, in certain harvests, increased pepper fruit numbers in field tests and red fruit weights in plastic house tests. Taken together, these results indicate that the screening procedure is rapid and reliable for the selection of potential biocontrol strains against P. capsici in pepper plants. In addition, these selected strains exhibited biocontrol activities against anthracnose, and some of the strains showed plant growth-promotion activities on pepper fruit.
Liao, Lisheng; Zhou, Jianuan; Wang, Huishan; He, Fei; Liu, Shiyin; Jiang, Zide; Chen, Shaohua; Zhang, Lian-Hui
Zeamines (ZMS), a class of polyamine-polyketide-nonribosomal peptide produced by bacterial isolate Dickeya zeae, were shown recently to be potent antibiotics against some bacterial pathogens. In this study, the results indicated that ZMS showed antifungal activity against Peronophythora litchii and other fungal pathogens. The activity of ZMS against the oomycete pathogen P. litchi, which causes the devastating litchi downy blight, was further investigated under in vitro and in vivo conditions. ZMS displayed potent inhibitory activity against the mycelial growth and sporangia germination of P. litchii. At a concentration of 2 μg/mL, about 99% of the sporangia germination was inhibited. Scanning electron microscopy and transmission electron microscopy analyses showed that treatment with ZMS could cause substantial damages to the oomycete endomembrane system. Furthermore, treatment of litchi fruits with ZMS solution significantly (P < 0.05) reduced the fruits decay and peel browning caused by P. litchii infection during storage at 28 °C. Taken together, our results provide useful clues on the antifungal mechanisms of ZMS, and highlight the promising potentials of ZMS as a fungicide, which in particular, may be useful for prevention and control of litchi fruits decay and browning caused by P. litchii infection during storage and transportation.
Lim, Sanghyun; Chisholm, Kenneth; Coffin, Robert H; Peters, Rick D; Al-Mughrabi, Khalil I; Wang-Pruski, Gefu; Pinto, Devanand M
Foliar diseases, such as late blight, result in serious threats to potato production. As such, potato leaf tissue becomes an important substrate to study biological processes, such as plant defense responses to infection. Nonetheless, the potato leaf proteome remains poorly characterized. Here, we report protein profiling of potato leaf tissues using a modified differential centrifugation approach to separate the leaf tissues into cell wall and cytoplasmic fractions. This method helps to increase the number of identified proteins, including targeted putative cell wall proteins. The method allowed for the identification of 1484 nonredundant potato leaf proteins, of which 364 and 447 were reproducibly identified proteins in the cell wall and cytoplasmic fractions, respectively. Reproducibly identified proteins corresponded to over 70% of proteins identified in each replicate. A diverse range of proteins was identified based on their theoretical pI values, molecular masses, functional classification, and biological processes. Such a protein extraction method is effective for the establishment of a highly qualified proteome profile.
Full Text Available In Latvia, climatic factors are influential in spreading of Fusarium head blight of cereals caused by Fusarium species. The most significant factor affecting the incidence of the disease in winter wheat is hightened temperature at the time of wheat anthesis. Field trials for the control of the disease in winter wheat were done in 2003-2004 using new fungicides applied at various rates by natural infection and artificial inoculation. Three species of causative agents: Fusarium avenaceum var. herbarum, F. gibbosum, F. culmorum were collected from infected seeds of wheat and used for inoculation of experimental plots at the concentration 106 conidia ml-1 (1:1:1 at the stage of full anthesis. Effective control of the disease was obtained through application of new fungicides with different active ingredient: Prosaro 250 EC (tebuconazole 125 G, prothioconazole 125 G L-1, Input 460 EC (spiroxamine 300 G, prothioconazole 160 G L-1. In conditions of artificial infection by severe attack of Fusarium spp. the application of fungicides containing tebuconazole at T3 gave significant influence on yield of winter wheat through plumpness of grains increase. High efficacy of fungicides against leaf infection with Erysiphe graminis and Drechslera tritici-repentis was also in the trial achieved. Application of fungicide containing cyproconazole and trifloxystrobin at T1 in the trial 2004 gave good control of Septoria tritici, E. graminis and D. triticirepentis.
Gosal, S.S.; Jitender Kaur, Adas; Minocha, J.L.
In vitro shoot cultures of two potato varieties viz., Kufri jyoti and Kufri Chandramukhi were gamma irradiated at 20 Gy and 40 Gy. Micro tubers were induced in micro propagated M1V3 generation. For heat tolerance micro tubers were induced at elevated (28 C ) incubation temperature (optimum being 20 1C ) and were characterized by early sowing, chlorophyll persistence and harvest index. The number of micro tubers/plant was highly reduced at elevated temperature and the resulting tubers exhibited distorted shapes and growth of apical buds. Thus obtained micro tubers exhibited better germination (62.3%) even in early sowing at relatively higher temperature. The progenies from putative heat tolerant plants were grown in the field by sowing at higher temperature for four subsequent generations. Heat tolerant plants segregated in each generation but the frequency of heat tolerant plants increased in the advanced generation. For developing late blight resistance micro tubers produced from irradiated shoot cultures were sown in pots and resulting plants were screened using detached leaf method. The progenies of putative resistant plants grown in the field were artificially inoculated with sporangial inoculum of Phytophthora infection's. Field grown plants exhibited segregation with respect to disease reaction and about 56 per cent plants showed resistance. Segregation was reduced during following generation and the frequency of resistant plants was increased up to 72.3 per cent. Thus, repeated selections has helped in developing stable mutants in both the varieties
Fernando Palha Leite
Full Text Available Eucalyptus Shoot Blight in the Vale do Rio Doce (ESBVRD is an anomaly that leads to reduced growth and, in more extreme cases, to death of eucalyptus plants. Initially diagnosed in plantations in the region of the Vale do Rio Doce, in the State of Minas Gerais, Brazil, this problem has also been found in plantations in other regions of the country and even in other countries. Although the symptoms of this anomaly are well-known, its causes are not yet understood. The aim of this study was to evaluate the cause-effect relationship between accumulation of manganese (Mn in eucalyptus clones and ESBVRD. Characterization of the environment in areas of greater occurrence of this problem in regard to soil, climate and fluctuation of the water table was undertaken in eucalyptus plantations of the Celulose Nipo-brasileira S.A. (Cenibra company in the region of the Vale do Rio Doce. Plant tissues were sampled in two situations. In the first situation, diagnosis occurred in the initial phase of the anomaly in clones with differentiated tolerance to the problem; in the second situation, diagnosis was made in a single clone, considered to be sensitive, in two time periods - in the phase with the strong presence of symptoms and in the recovery phase, in areas of occurrence and in areas of escape from the problem. The most ESBVRD-sensitive clone showed much higher (4.8 times higher leaf Mn contents than more tolerant clones. In plants with the anomaly, Mn leaf contents were greater than 3,070 mg kg-1, much greater than the quantity found in those without the anomaly (734 mg kg-1. In the period in which the symptoms began to wane, there was a sharp decline in leaf Mn contents, from 2,194 to 847 mg kg-1. Manganese content in the above ground part and plant litter (44.4 g ha-1 in the area of occurrence of the anomaly was three times greater than that found in these same components (14.1 g ha-1 in the area of absence of the symptom. Based on the evidence found
1973-01-01In the Netherlands, the source of inoculum of the late blight fungus on tomatoes is the late blight fungus on potato crops. In regions of Europe mentioned, where tomatoes are grown in the open, P. infestans on tomatoes is the main source of inoculum. Especially in
Pacilly, Francine C.A.; Groot, Jeroen C.J.; Hofstede, Gert Jan; Schaap, Ben F.; Lammerts van Bueren, Edith
Potato late blight, caused by Phytophthora infestans, is one of the main diseases in potato production, causing major losses in yield. Applying environmentally harmful fungicides is the prevailing and classical method for controlling late blight, thus contaminating food and water. There is
Yang, Fen; Svensson, Birte; Finnie, Christine
Fusarium seedling blight in cereals can result in significant reductions in plant establishment but has not received much attention. The disease often starts during seed germination due to sowing of the seeds infected by Fusarium spp. including Fusarium graminearum. In order to gain the first...... provides the first molecular insight into Fusarium seedling blight....
The tomato late blight pandemic of 2009 made late blight into a household term in much of the Eastern United States. Many home gardeners and organic producers lost most if not all of their tomato crop, and their experiences were reported in the mainstream press. Some CSAs (Community Supported Agricu...
Potatoes are grown in Israel in two growing seasons, autumn and spring. Two foliar diseases, early blight (Alternaria solani) and late blight (Phytophthora infestans) threaten the crop and if not managed properly, may induce substantial yield losses. Concepts for the integration of genotype resistance, age-related resistance ...
Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). When infiltrated into host leaves, Ea induces reactions similar to a hypersensitive response (HR). Type III (T3SS) associated effectors, especially DspA/E, are suspected to ha...
Plant scientists make inferences and predictions from phylogenetic trees to solve scientific problems. Crop losses due to disease damage is an important problem that many plant breeders would like to solve, so the ability to predict traits like disease resistance from phylogenetic trees derived from...
Jae Eun Lee,
Full Text Available This study was conducted to control the seed borne pathogens (Alternaria spp. of carrot and to examine the seed germination rate by using 13 environment friendly agricultural materials instead of conventional chemicals for organic cultivation. The growth inhibiting effects on pathogens showed the different responses according to each agricultural material and effective 7 materials against seed borne pathogens were selected. Among 7 materials, the carrot seeds sterilized with plant extracts, Tanger Stop and Land Saver were not germinated at all. The germination rate of seeds sterilized with other materials showed the similar levels with reference chemical (Benlate-T and non-treated seeds. Infection rates of seeds sterilized with seaweed extract, Bellopper for controlling A. radicina and plant extract, Ssial-100 for A. dauci were similar or low infection rate compared with reference chemical. The germination rate and root length of seeds sterilized with Bellopper and Ssial-100 was similar or superior to those of chemical sterilized seeds. The optimal condition seemed to be a little bit different depending on the concentration of materials. As a result, the sterilization of carrot seeds by using the environment friendly materials could be effectively utilized as a technology to inhibit the infection of seed-borne pathogens
Full Text Available When asked by the Department of Homeland Security to create potential terrorism scenarios, even “Out of the Box Thinkers” initially failed to come up with the following scenario. Oil tankers, refineries, nuclear plants, etc., are obvious potential terrorists’ targets, and adequate measures are being taken to protect them. However, what if the target were to be a non-food commodity product, such as natural rubber tree plantations located in places as remote as southeast Asian countries like Thailand or Indonesia? Would it be of concern? At first thought “maybe not”, but think again. What could the release of a deadly microorganism (fungus/virus/bacteria in a rubber tree plantation in Indonesia, Malaysia or Thailand possibly mean to you or the world economy?
Nowakowska, Marzena; Nowicki, Marcin; Kłosińska, Urszula; Maciorowski, Robert; Kozik, Elżbieta U
Late blight (LB) caused by the oomycete Phytophthora infestans continues to thwart global tomato production, while only few resistant cultivars have been introduced locally. In order to gain from the released tomato germplasm with LB resistance, we compared the 5-year field performance of LB resistance in several tomato cultigens, with the results of controlled conditions testing (i.e., detached leaflet/leaf, whole plant). In case of these artificial screening techniques, the effects of plant age and inoculum concentration were additionally considered. In the field trials, LA 1033, L 3707, L 3708 displayed the highest LB resistance, and could be used for cultivar development under Polish conditions. Of the three methods using controlled conditions, the detached leaf and the whole plant tests had the highest correlation with the field experiments. The plant age effect on LB resistance in tomato reported here, irrespective of the cultigen tested or inoculum concentration used, makes it important to standardize the test parameters when screening for resistance. Our results help show why other reports disagree on LB resistance in tomato.
Full Text Available Late blight (LB caused by the oomycete Phytophthora infestans continues to thwart global tomato production, while only few resistant cultivars have been introduced locally. In order to gain from the released tomato germplasm with LB resistance, we compared the 5-year field performance of LB resistance in several tomato cultigens, with the results of controlled conditions testing (i.e., detached leaflet/leaf, whole plant. In case of these artificial screening techniques, the effects of plant age and inoculum concentration were additionally considered. In the field trials, LA 1033, L 3707, L 3708 displayed the highest LB resistance, and could be used for cultivar development under Polish conditions. Of the three methods using controlled conditions, the detached leaf and the whole plant tests had the highest correlation with the field experiments. The plant age effect on LB resistance in tomato reported here, irrespective of the cultigen tested or inoculum concentration used, makes it important to standardize the test parameters when screening for resistance. Our results help show why other reports disagree on LB resistance in tomato.
Full Text Available Fusarium head blight (FHB caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed.
Kim, In-Yong; Pusey, Paul Lawrence; Zhao, Youfu; Korban, Schuyler S; Choi, Hyungsoo; Kim, Kyekyoon Kevin
Microencapsulation and controlled release of the biocontrol agent Pantoea agglomerans strain E325 (E325), an antagonist to the bacterial plant pathogen Erwinia amylovora that causes fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 μm in diameter, were fabricated to encapsulate E325 within the core, along with nutrients, to preserve viability and promote proliferation. Controlled release of E325 was achieved by separately adjusting alginate concentrations in the shell and core solutions, and by modifying the AMC size. Viability of E325 was monitored via fluorescent staining, revealing either lack of or minimal stress during or after encapsulation. Proliferation of E325 within AMCs, followed by their subsequent release, and colonization activities within confines of apple flowers were studied under different encapsulation conditions using rfp-labeled E325 to obtain highly promising results. This study provided a 'proof of concept' of the successful use of a microencapsulated biocontrol agent, E325, against E. amylovora, and could serve as a model for further studies on the development of effective plant disease management strategies. Copyright © 2012 Elsevier B.V. All rights reserved.
Kumar, Rishikesh; Soni, Madhvi; Mondal, Kalyan K
Bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a major disease of pomegranate. Xap secretes effector proteins via type III secretion system (T3SS) to suppress pathogen-associated molecular pattern (PAMP)-triggered plant immunity (PTI). Previously we reported that XopN, a conserved effector of Xap, modulate in planta bacterial growth, and blight disease. In continuation to that here we report the deletion of XopN from Xap caused higher accumulation of reactive oxygen species (ROS) including H 2 O 2 and O 2 - . We quantitatively assessed the higher accumulation of H 2 O 2 in pomegranate leaves infiltrated with Xap ΔxopN compared to Xap wild-type. We analysed that 1.5 to 3.3 fold increase in transcript expression of ROS and flg22-inducible genes, namely FRK1, GST1, WRKY29, PR1, PR2 and PR5 in Arabidopsis when challenged with Xap ΔxopN; contrary, the up-regulation of all the genes were compromised when challenged with either Xap wild-type or Xap ΔxopN+xopN. Further, we demonstrated the plasma-membrane based localization of XopN protein both in its natural and experimental hosts. All together, the present study suggested that XopN-T3SS effector of Xap gets localized in the plasma membrane and suppresses ROS-mediated early defense responses during blight pathogenesis in pomegranate. Copyright © 2016 Elsevier GmbH. All rights reserved.
Treikale, O; Priekule, I; Javoisha, B; Lazareva, L
Fusarium head blight (FHB) of wheat has, in recent years, been a very important worldwide disease in intensive growing of cereal. The objectives of this study were to evaluate the occurrence of FHB in wheat in Latvia and to identify the Fusarium species involved. This paper describes the distribution of Fusarium species that were isolated from samples representing winter and spring wheat varieties in Latvia, identified both by the classical morphological analyses of J. Leslie and B. Summerell (2006) and by PCR. The FHB incidence range in winter wheat was 1-20%, in spring wheat was 1-42%. The most significant factor affecting the incidence of fusarial head blight in wheat in Latvia was heightened temperature at the time of an thesis of wheat. In winter wheat 9 Fusarium species caused FHB: F. culmorum, F. avenaceum, F. graminearum, F. equiseti, F. poae, F. oxysporum, F. cerealis, F. sporotrichoides and F. verticillioides were identified by morphological characterization, and 5 were confirmed by PCR-analysis. After experience of 5 years, it can be concluded that the most frequent in winter wheat were F. poae and F. culmorum. In spring wheat from F. culmorum was dominant among 8 Fusarium species. Among 13 varieties of spring wheat, three were sensitive ('Chamsin', 'W 166', 'Azurite') and one was resistant ('Granny') to FHB in conditions of high natural infection in 2009. The monitoring surveys demonstrate a significant presence of FHB in spring wheat in conditions of heightened temperature at the time of flowering in Latvia.
% yield losses. (Prathuangwong and Amnuaykit, 1987). It is difficult to distinguish symptoms of this disease from bacterial leaf blight disease and leaf rust fungus, especially in the early phase of disease progression (Frederick et al., 2002). The.
The minimum inhibitory concentration (MIC) of methanol leaf extract show least activity against Yersinia enterocolitica and Pseudomonas aeruginosa (MIC = 100 mg/ml) and higher activity of MIC at 50 mg/ml against the other bacterial test organisms. The chloroform leaf extract MIC of 100 mg/ml had least activity against ...
Sharma, R.; Kant, A.; Kaushal, R.P.
To induce resistance in pea against Ascochyta blight and powdery mildew through mutagenesis, two locally grown cultivars Lincoln and Palam Priya were subjected to three doses each of gamma rays (10, 15 and 20 kR) and chemical mutagen ethylmethane sulfonate (0.1, 0.2 and 0.3%). Reduced germination was observed in response to mutagen treatment in both cultivars. Phenotypic changes were observed in M1 and M2 generations of both the cultivars. In M2 generation twenty-seven mutants of Lincoln and sixteen of Palam Priya were found resistant to Ascochyta blight under natural epiphytotic conditions. High level of resistance in M2 generation against powdery mildew could not be achieved. Plant progenies in the M3 generation were also evaluated for resistance to Ascochyta pinodes as well as Erysiphe pisi through detached leaf technique. Six mutants of Lincoln and only one of Palam Priya were found resistant to A. pinodes. One mutant of Palam Priya (P15-3) showed resistance to both the pathogens. Increased phenylalanine ammonia lyase activity was observed in all the resistant mutants. New isoforms of peroxidase could be detected in the mutant P15-3 (Palam Priya) and also in L0.2-1 (Lincoln). However, not much variation for esterase could be observed [it
Shinde, Balkrishna A; Dholakia, Bhushan B; Hussain, Khalid; Panda, Sayantan; Meir, Sagit; Rogachev, Ilana; Aharoni, Asaph; Giri, Ashok P; Kamble, Avinash C
Exploration with high throughput leaf metabolomics along with functional genomics in wild tomato unreveal potential role of steroidal glyco-alkaloids and phenylpropanoids during early blight resistance. Alternaria solani severely affects tomato (Solanum lycopersicum L.) yield causing early blight (EB) disease in tropical environment. Wild relative, Solanum arcanum Peralta could be a potential source of EB resistance; however, its underlying molecular mechanism largely remains unexplored. Hence, non-targeted metabolomics was applied on resistant and susceptible S. arcanum accessions upon A. solani inoculation to unravel metabolic dynamics during different stages of disease progression. Total 2047 potential metabolite peaks (mass signals) were detected of which 681 and 684 metabolites revealed significant modulation and clear differentiation in resistant and susceptible accessions, respectively. Majority of the EB-triggered metabolic changes were active from steroidal glycol-alkaloid (SGA), lignin and flavonoid biosynthetic pathways. Further, biochemical and gene expression analyses of key enzymes from these pathways positively correlated with phenotypic variation in the S. arcanum accessions indicating their potential role in EB. Additionally, transcription factors regulating lignin biosynthesis were also up-regulated in resistant plants and electrophoretic mobility shift assay revealed sequence-specific binding of rSaWRKY1 with MYB20 promoter. Moreover, transcript accumulation of key genes from phenylpropanoid and SGA pathways along with WRKY and MYB in WRKY1 transgenic tomato lines supported above findings. Overall, this study highlights vital roles of SGAs as phytoalexins and phenylpropanoids along with lignin accumulation unrevealing possible mechanistic basis of EB resistance in wild tomato.
Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj
The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (pmitis was 75, 110 μg/ml (psalivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study.
Tumwine, J.; Frinking, H.D.; Jeger, M.J.
Cultural control measures against tomato late blight (Phytophthora infestans) were evaluated in six field experiments over 3 years in Uganda. Each experiment included sanitation (removal of diseased plant tissues), fungicide (mancozeb) application, and an untreated control, as standard treatments.
Full Text Available Isolates of ascochyta blight fungi, two of Ascochyta pisi, four of Mycosphaerella pinodes and four of Phoma pinodella were stored: A - on slants under mineral oil, B - on CN's medium agar disks, and as conidial suspension: C - in glycerine, D · in water. Viability and pathogenicity of recovered cultures after each consecutive year were assesed from 1991 to 1999. The compared parameters were first of all strongly influenced by the preservation method, but fungus species and number of years had a minor importance. The best for longer storage was method "A" because after 9 years the isolates were viable, highly pathogenic, and cultures recovered from them were clean. Thc method "C'' is good for short keeping (2-3 years, as conidia in vials need only small space and gave clean cultures.
Cooke, L R; Schepers, H T A M; Hermansen, A
Phytophthora infestans, the causal agent of late blight, is a major threat to potato production in northwestern Europe. Before 1980, the worldwide population of P. infestans outside Mexico appeared to be asexual and to consist of a single clonal lineage of A1 mating type characterized by a single...... genotype. It is widely believed that new strains migrated into Europe in 1976 and that this led to subsequent population changes including the introduction of the A2 mating type. The population characteristics of recently collected isolates in NW Europe show a diverse population including both mating types......, sexual reproduction and oospores, although differences are observed between regions. Although it is difficult to find direct evidence that new strains are more aggressive, there are several indications from experiments and field epidemics that the aggressiveness of P. infestans has increased in the past...
Full Text Available In the Gulf and after gaining independence in the 1960s and 1970s many cities witnessed a staggering rapid urban growth. The urban centers, which formed the central parts of these cities, underwent continuous pressures of destruction and redevelopment. A large number of these centers have been often demolished and replaced by alien imported high-rise buildings. The urban cores which escaped complete demolition have survived as isolated pockets in the middle of hybrid environments. This dilemma raises important questions; is this surviving cultural heritage blight or blessing? Is it "blight" and obstacle that stifles our cities from moving forward to aspire for a bright and prosperous future, or is it "blessing" an asset that can form a major catalyst to promote our cities while maintaining strong roots with their past? Accordingly, what should be the future of these surviving historic centers? Will they be demolished to pave way for more ambitious growth or can they be conserved and sustained for present and future generations? Will the historic city, the heart of urban life and the main protector of our cities identities, survive and continue to be places for living within the emerging global cities of today and tomorrow? This paper attempts to highlight the importance of dealing with the conservation and development issue, by raising and discussing the following question: How can our cultural heritage be a setting of appropriate conservation and development in the emerging global environments? In order to discuss this issue, three historic cities from the Gulf; Old Dubai in UAE, Old Jeddah in Saudi Arabia and Old Doha in Qatar will form the setting of this research.
Full Text Available Delphinella shoot blight (Delphinella abietis attacks true firs (Abies spp. in Europe and North America. Especially subalpine fir (A. lasiocarpa, one of the main Christmas tree species in Norway, is prone to the disease. The fungus kills current year needles, and in severe cases entire shoots. Dead needles become covered with black fruiting bodies, both pycnidia and pseudothecia. Delphinella shoot blight has mainly been a problem in humid, coastal regions in the northwestern part of Southern Norway, but, probably due to higher precipitation in inland regions during recent years, heavy attacks were found in 2011 in a field trial with 76 provenances of subalpine fir in Southeastern Norway. However, the amount of precipitation seemed less important once the disease had established in the field. Significant differences in susceptibility between provenances were observed. In general, the more bluish the foliage was, the healthier the trees appeared. The analysis of provenance means indicated that, at least for the southern range, the disease ratings were correlated with foliage color. This study also includes isolation, identification, a pathogenicity test, a seed test and electron microscopy of the wax layer on the needles. The fungus was identified based on the morphology of spores and by sequencing the Internal Transcribed Spacer (ITS regions of the ribosomal DNA. Koch’s postulates were fulfilled. The fungus was found present on newly harvested seeds and may therefore spread via international seed trade. When comparing the wax layers on green and blue needles, those of the latter were significantly thicker, a factor that may be involved in disease resistance.
... Español Eye Health / Eye Health A-Z Bacterial Keratitis Sections What Is Bacterial Keratitis? Bacterial Keratitis Symptoms ... Lens Care Bacterial Keratitis Treatment What Is Bacterial Keratitis? Leer en Español: ¿Qué Es la Queratitis Bacteriana? ...
Marcela G. TEODORO
Full Text Available Leaf blight and defoliation caused by Teratosphaeria species is one of the most important leaf diseases of Eucalyptus globulus. Due to the importance of this tree species for the production of pulp and paper, and recent reports of severe leaf disease symptoms in Brazil, the present study was conducted to identify the pathogen(s involved. Symptomatic leaves were collected in the Brazilian states of Paraná and Rio Grande do Sul, single ascospore cultures established, and isolates were investigated using DNA-based molecular tools. A species-specific PCR and sequence data from the nuclear ribosomal DNA operon were used for species identification. The following seven species were identified: Mycosphaerella scytalidii, Dissoconium dekkeri (=M. lateralis, Teratosphaeria ohnowa, T. perpendicularis, T. pseudafricana, T. flexuosa and T.nubilosa. Of the recorded species, T. nubilosa is regarded as the most serious threat to the cultivation of E. globulus in the states surveyed.
Franceschini, M. H. D.; Bartholomeus, H.; van Apeldoorn, D.; Suomalainen, J.; Kooistra, L.
Productivity of cropping systems can be constrained simultaneously by different limiting factors and approaches allowing to indicate and identify plants under stress in field conditions can be valuable for farmers and breeders. In organic production systems, sensing solutions are not frequently studied, despite their potential for crop traits retrieval and stress assessment. In this study, spectral data in the optical domain acquired using a pushbroom spectrometer on board of a unmanned aerial vehicle is used to evaluate the potential of this information for assessment of late blight (Phytophthora infestans) incidence on potato (Solanum tuberosum) under organic cultivation. Vegetation indices formulations with two and three spectral bands were tested for the complete range of the spectral information acquired (i.e., from 450 to 900 nm, with 10 nm of spectral resolution). This evaluation concerned the discrimination between plots cultivated with only one resistant potato variety in contrast with plots with a variety mixture, with resistant and susceptible cultivars. Results indicated that indices based on three spectral bands performed better and optimal wavelengths (i.e., near 490, 530 and 670 nm) are not only related to chlorophyll content but also to other leaf pigments like carotenoids.
M. H. D. Franceschini
Full Text Available Productivity of cropping systems can be constrained simultaneously by different limiting factors and approaches allowing to indicate and identify plants under stress in field conditions can be valuable for farmers and breeders. In organic production systems, sensing solutions are not frequently studied, despite their potential for crop traits retrieval and stress assessment. In this study, spectral data in the optical domain acquired using a pushbroom spectrometer on board of a unmanned aerial vehicle is used to evaluate the potential of this information for assessment of late blight (Phytophthora infestans incidence on potato (Solanum tuberosum under organic cultivation. Vegetation indices formulations with two and three spectral bands were tested for the complete range of the spectral information acquired (i.e., from 450 to 900 nm, with 10 nm of spectral resolution. This evaluation concerned the discrimination between plots cultivated with only one resistant potato variety in contrast with plots with a variety mixture, with resistant and susceptible cultivars. Results indicated that indices based on three spectral bands performed better and optimal wavelengths (i.e., near 490, 530 and 670 nm are not only related to chlorophyll content but also to other leaf pigments like carotenoids.
Alfalfa producers count on the first harvest in late spring to deliver the highest tonnage and best quality of forage of the year. A late frost can significantly reduce both yield and quality. Losses are due not only to the physical damage from freezing of the alfalfa stem and leaves but also from d...
Bossa-Castro, Ana M; Tekete, Cheick; Raghavan, Chitra; Delorean, Emily E; Dereeper, Alexis; Dagno, Karim; Koita, Ousmane; Mosquera, Gloria; Leung, Hei; Verdier, Valérie; Leach, Jan E
Quantitative trait loci (QTL) that confer broad-spectrum resistance (BSR), or resistance that is effective against multiple and diverse plant pathogens, have been elusive targets of crop breeding programmes. Multiparent advanced generation intercross (MAGIC) populations, with their diverse genetic composition and high levels of recombination, are potential resources for the identification of QTL for BSR. In this study, a rice MAGIC population was used to map QTL conferring BSR to two major rice diseases, bacterial leaf streak (BLS) and bacterial blight (BB), caused by Xanthomonas oryzae pathovars (pv.) oryzicola (Xoc) and oryzae (Xoo), respectively. Controlling these diseases is particularly important in sub-Saharan Africa, where no sources of BSR are currently available in deployed varieties. The MAGIC founders and lines were genotyped by sequencing and phenotyped in the greenhouse and field by inoculation with multiple strains of Xoc and Xoo. A combination of genomewide association studies (GWAS) and interval mapping analyses revealed 11 BSR QTL, effective against both diseases, and three pathovar-specific QTL. The most promising BSR QTL (qXO-2-1, qXO-4-1 and qXO-11-2) conferred resistance to more than nine Xoc and Xoo strains. GWAS detected 369 significant SNP markers with distinguishable phenotypic effects, allowing the identification of alleles conferring disease resistance and susceptibility. The BSR and susceptibility QTL will improve our understanding of the mechanisms of both resistance and susceptibility in the long term and will be immediately useful resources for rice breeding programmes. © 2018 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Full Text Available Early blight caused by Alternaria solani and late blight caused by Phytophthora infestans are the major diseases of tomato (Lycopersicon esculentum in Cameroon. The effect of both diseases on fruit yield was evaluated during the 1995 growing season in Dschang, Cameroon.Ten varieties were planted in the first trial (March-July and nine in the second (July- November. In both trials, plots were sprayed weekly with Ridomil Plus (2.0 kg/ha before flowering and with maneb (1.6 kg/ha after flowering. Early blight was more severe in the early part of the first trial, while late blight caused most damage during the second. Marketable yields varied according to variety. High yields in sprayed plots were obtained in Dona F1 (61.63 t/ha and Heinz 1370 (68.24 t/ha during the first trial, and in Fline (58.35 t/ha, Mecline (64.25 t/ha, and Moboline (55.16 t/ha during the second trial. Percent fruit infection in sprayed plots caused by both diseases varied according to variety from 12 to 65% in the first season and from 14 to 52% in the second, while losses in marketable yields for both blights were as high as 100% in unsprayed plots.
Full Text Available Ascochyta blight (AB caused by Ascochyta rabiei (Pass. Labr. is an important and widespread disease of chickpea (Cicer arietinum L. worldwide. The disease is particularly severe under cool and humid weather conditions. Breeding for host resistance is an efficient means to combat this disease. In this paper, attempts have been made to summarize the progress made in identifying resistance sources, genetics and breeding for resistance, and genetic variation among the pathogen population. The search for resistance to AB in chickpea germplasm, breeding lines and land races using various screening methods has been updated. Importance of the genotype × environment (GE interaction in elucidating the aggressiveness among isolates from different locations and the identification of pathotypes and stable sources of resistance have also been discussed. Current and modern breeding programs for AB resistance based on crossing resistant/multiple resistant and high-yielding cultivars, stability of the breeding lines through multi-location testing and molecular marker-assisted selection method have been discussed. Gene pyramiding and the use of resistant genes present in wild relatives can be useful methods in the future. Identification of additional sources of resistance genes, good characterization of the host–pathogen system, and identification of molecular markers linked to resistance genes are suggested as the key areas for future study.
Soil and irrigation management have been used to optimize crop production. However,their effects on microclimate, development, and controls of potato diseases have not been adequately quantified. The effects of soil, crop, and water management on development of potato early blight and late blight we...
Pel, M.; Foster, S.J.; Park, T.H.; Rietman, H.; Arkel, van G.; Jones, J.D.G.; Eck, van H.J.; Jacobsen, E.; Visser, R.G.F.; Vossen, van der E.A.G.
Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases of potato. Resistance (R) genes from the wild species Solanum demissum have been used by breeders to generate late-blight-resistant cultivars but resistance was soon overcome by the pathogen. A more
Sparks, Adam H.; Raymundo, R.; Simon, R.; Forbes, G.; Garrett, Karen A.
This poster prioritizes efforts to manage late blight and measuring their impact now and under future climate scenarios demands a national and global perspective. We used a model in Geographic Information Systems (GIS) to create late blight severity predictions under current and future climate conditions. LTRA-4 (Practices and Strategies for Vulnerable Agro-Ecosystems)
Full Text Available Eucalyptus pellita is often grown in monoculture can be susceptible to disease whether grown in the nursery or the field. Currently in the plantation of PT Surya Hutani Jaya Sebulu is developing E. pellita derived from seed and clonal. The results were then called family. To determine the benefits to trees the company deliberately does not preserve this area so there will be generated trees family that excel in both productivity and resistance to pests and diseases. This study is aimed at determining the symptoms and signs of disease on the leaves the microorganisms that cause disease on the leaves as well as the incidence and severity of pathogen that attacks the leaves of E. pellita. The research was conducted at PT Surya Hutani Jaya Sebulu Kutai Kartanegara Regency East Kalimantan and continued with the identification of pathogens at the Laboratory of Forest Protection Faculty of Forestry University of Mulawarman. The object of this research was E. pellita of a 6 year old plantation spacing of 3 amp61620 2 m. The origin of E. pellita is a clone from Riau. Symptoms of the disease found at the progeny test were leaf spot and leaf blight. The pathogens were Cercospora sp. Pestalotia sp. Curvularia sp. Bipolaris sp. Marsonina sp. and Dactylaria sp. The incidence of leaf spot pathogen was 83.3 and leaf blight was 80.6 with the severity of 9.7 and 12.5 respectively.
Akhtar, K.P.; Saleem, M.Y.; Asghar, M.
The reaction of 82 tomato genotypes belonging to 8 Solanum and a Lycopersicon species against Phytophthora infestans causing late blight was determined using detached-leaf and whole-plant assays. None of the test genotypes was immune or highly resistant. Of the 82 commercial and wild genotypes only TMS-2 (male-sterile and characterized by indeterminate growth) belonging to Lycopersicon esculentum was resistant with severity index of 2.4 in the detached-leaf assay on 0-5 scale (where 5 was highly susceptible) and percent disease index (%DI) of 23.3% under the whole-plant assay. Among the remaining genotypes, 41 were susceptible and 40 were highly susceptible under the detached-leaf assay, while 18 were susceptible and 63 were highly susceptible under the whole-plant assay. However, there was a significant difference in %DI for genotypes under the whole-plant assay. The response of whole-plants to inoculation with P. infestans in the detached-leaf assay was similar in all cases. The overall screening results indicate that TMS-2 is a good source of resistance and it can be useful for the development of tomato hybrid cultivars resistant to late blight. (author)
Full Text Available Fire blight, which is an important disease of apples and pears, has never been detected in continental Finland. In this study the suitability of the Finnish climate for apple blossom blight infections by Erwinia amylovora was evaluated with the epidemiological model MaryblytTM. This was done in fourteen locations, and for two apple cultivars differing in flowering times. Climatic conditions were predicted to be suitable for blossom infections in 18 - 51% of the years, and the annual period of suitable conditions was predicted to last up to two to five days, depending on the location and apple cultivar. The suitable period was predicted to be longer in some locations in central Finland than in those in the southernmost parts of the country. Based on these results the official surveys that are carried out to confirm the absence of fire blight in Finland cannot be targeted only to some parts of the country.
Roos, Karen L.; van de Beek, Diederik
Bacterial meningitis is a neurological emergency. Empiric antimicrobial and adjunctive therapy should be initiated as soon as a single set of blood cultures has been obtained. Clinical signs suggestive of bacterial meningitis include fever, headache, meningismus, vomiting, photophobia, and an
Palazzini, J M; Torres, A M; Chulze, S N
Fusarium head blight (FHB) caused by Fusarium graminearum species complex is a devastating disease that causes extensive yield and quality losses to wheat around the world. Fungicide application and breeding for resistance are among the most important tools to counteract FHB. Biological control is an additional tool that can be used as part of an integrated management of FHB. Bacillus velezensis RC 218, Brevibacillus sp. RC 263 and Streptomyces sp. RC 87B were selected by their potential to control FHB and deoxynivalenol production. The aim of this work was to test the tolerance of these biocontrol agents to triazole-based fungicides such as Prothioconazole, tebuconazole and metconazole. Bacterial growth was evaluated in Petri dishes using the spread plating technique containing the different fungicides. Bacillus velezensis RC 218 and Streptomyces sp. RC 87B showed better tolerance to fungicides than Brevibacillus sp. RC 263. Complete growth inhibition was observed at concentrations of 20 μg ml -1 for metconazole, 40 μg ml -1 for tebuconazole and 80 μg ml -1 for prothioconazole. The results obtained indicate the possibility of using these biocontrol agents in combination with fungicides as part of an integrated management to control FHB of wheat. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Full Text Available Ascochyta blight, an infection caused by a complex of Ascochyta pinodes, Ascochyta pinodella, Ascochyta pisi, and/or Phoma koolunga, is a destructive disease in many field peas (Pisum sativum L.-growing regions, and it causes significant losses in grain yield. To understand the composition of fungi associated with this disease in Zhejiang Province, China, a total of 65 single-pycnidiospore fungal isolates were obtained from diseased pea samples collected from 5 locations in this region. These isolates were identified as Ascochyta pinodes by molecular techniques and their morphological and physiological characteristics. The mycelia of ZJ-1 could penetrate pea leaves across the stomas, and formed specific penetration structures and directly pierced leaves. The resistance level of 23 available pea cultivars was tested against their representative isolate A. pinodes ZJ-1 using the excised leaf-assay technique. The ZJ-1 mycelia could penetrate the leaves of all tested cultivars, and they developed typical symptoms, which suggested that all tested cultivars were susceptible to the fungus. Chemical fungicides and biological control agents were screened for management of this disease, and their efficacies were further determined. Most of the tested fungicides (11 out of 14 showed high activity towards ZJ-1 with EC50 < 5 μg/mL. Moreover, fungicides, including tebuconazole, boscalid, iprodione, carbendazim and fludioxonil, displayed more than 80% disease control efficacy under the recorded conditions. Three biocontrol strains of Bacillus sp. and one of Pantoea agglomerans were isolated from pea-related niches and significantly reduced the severity of disease under greenhouse and field conditions. To our knowledge, this is the first study on ascochyta blight in field peas, and results presented here will be useful for controlling the disease in this area.
Eny Ida Riyanti
Full Text Available Late blight caused by Phytophthora infestans is an important disease on potato. Several potato hybrids have been generated by crossing local varieties (Atlantic and Granola with Katahdin SP951 which contains late blight resistance gene RB. Prior to release, these hybrids need to be evaluated for their environ-mental effects on non-target organisms and natural pests and diseases. The objectives of the study were to investigate the effect of LBR potato hybrids on beneficial soil microbes, pests and diseases. The trial was conducted in the confined field trial (CFT in Lembang, West Java. The parental non-transgenic (NT clones (Granola, Atlantic and Katahdin and LBR hybrids (four clones of Atlantic x Katahdin SP951 hybrids; 10 clones of Granola x Katahdin SP951 were planted at a plant spacing of 30 cm x 70 cm. Fungicide applications were used as treat-ments (no spray, five and twenty times sprays. The experi-ment was arranged in a randomized completely block design with three replications. The parameters determined were popula-tions of N2 fixing and P solubilizing bacteria, soil C/N ratio as well as natural pests and diseases. The results showed that the transgenic LBR potato hybrids did not have negative effect on N fixing bacteria. The bacterial populations were around 1010-11 cells g-1 soil before planting, 1012 cells at 1.5 months after planting (MAP and 108 cells after harvest. For P- solubilizing bacteria, their populations were 1010 cells before planting, 1012 cells at 1.5 MAP and 1011 cells g-1 soil after harvest. The soil C/N ratio of the transgenic plot was not statistically different compared to non-transgenic plot, i.e. 12-15 before planting, 10-11 at 1.5 MAP, and 10 after harvest in non-spray plot. Pests and diseases such as Alternaria solani, Liriomyza, potato tubber moth, aphid and mites on the transgenic and non-transgenic plots were statistically not different. The resistance score for A. solani was 7.2 (parental tansgenic and
In the Netherlands, Fusarium head blight of wheat is predominantly caused by Fusarium culmorum . A low infection level leads to important yield losses and contaminates the grain with mycotoxins, particularly deoxynivalenol. This mycotoxin is suggested to have toxic
Turner, R Steven
By the mid-1980s nucleic-acid based methods were penetrating the farthest reaches of biological science, triggering rivalries among practitioners, altering relationships among subfields, and transforming the research front. This article delivers a "bottom up" analysis of that transformation at work in one important area of biological science, plant pathology, by tracing the "molecularization" of efforts to understand and control one notorious plant disease -- the late blight of potatoes. It mobilizes the research literature of late blight science as a tool through which to trace the changing typography of the research front from 1983 to 2003. During these years molecularization intensified the traditional fragmentation of the late blight research community, even as it dramatically integrated study of the causal organism into broader areas of biology. In these decades the pathogen responsible for late blight, the oomycete "Phytophthora infestans," was discovered to be undergoing massive, frightening, and still largely unexplained genetic diversification -- a circumstance that lends the episode examined here an urgency that reinforces its historiographical significance as a case-study in the molecularization of the biological sciences.
José Renato de Abreu
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.
Among the many diseases of potato (Solanum tuberosum L.), which is the third food crop in the world after wheat and rice, late blight caused by the oomycete pathogen Phytophthora infestans, is one of the most serious diseases. In the last century, major resistance (R)
S.A. Mehlenbacher; R.N. Brown; J.W. Davis; H. Chen; N.V. Bassil; D.C. Smith; Thomas L. Kubisiak
A total of 1,110 decamer primers were screened for RAPD markers linked to a dominant allele in hazelnut (Corylus avellana) that confers resistance to eastern filbert blight caused by Anisogramma anomnala. Twenty RAPD markers linked in coupling, and five markers linked in repulsion, were found. A seedling population was used to...
Goverse, A.; Struik, P.C.
This paper reports on a debate on intriguing propositions relating to the scientific, agronomic, societal and economic impact of the BIOEXPLOIT project, focusing on late blight resistance in potato. It discusses (i) whether identifying pathogen effectors will facilitate selecting durable R genes,
Chaerani, R.; Smulders, M.J.M.; Linden, van der C.G.; Vosman, B.; Stam, P.; Voorrips, R.E.
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
Al Etoum, Niebal Mohd Ibrahim; Mowafi, Hanan Sami Mohammad; Al Zubaidi, Faraj Hamad Salem
The study aims to highlight the benefits and blights of the due commandment (intestate law) under Jordanian law for the year (2010) in the article (279). The study came in two sections, the first one dealt with the concept of due commandment, its legitimacy, verdict and terms; in the second section, I've dealt with the persons entitled to due…
Sheath blight caused by Rhizoctonia solani is one of the most damaging diseases of rice worldwide. To understand the molecular mechanism of resistance, we identified 450 differentially expressed genes in a resistant rice cultivar Jasmine 85 after R. solani infection with a combination of DNA microar...
Rhizoctonia web blight is a reoccurring problem in compact varieties of container-grown azalea (Rhododendron sp.) in the Gulf Coast States. During the summers of 2002 and 2003, disease severity was measured weekly in the inoculated center plant of plots consisting of 49 ‘Gumpo’ azalea plants. Plant ...
Fusarium Head Blight is a disease of cereal crops that causes severe yield losses and mycotoxin contamination of grain. The main causal pathogen, Fusarium graminearum, produces the trichothecene toxins deoxynivalenol or nivalenol as virulence factors. Nivalenol-producing isolates are most prevalent ...
B. subtilis in culture also inhibited the mycelia growth of all tested pathogenic fungi with inhibitory zones of between 40.0% to 57.8%. The inhibitory activities of the compost-inhabiting microbes might partly be responsible for the efficacy of compost in reducing seedling blight diseases of crops. (African Journal of ...
Full Text Available Incidence of Phytophthora blight of hot pepper (Capsicum annuum and yield (fresh weight of pepper fruits were investigated at four separate fields located in Cheongwon, Boeun, Eumsung, and Goesan, which are major pepper production areas in Chungcheongbuk-Do. In all of the experimental fields except the Goesan field, increased incidence of Phytophthora blight led to decreased yield of pepper fruits. The harvest time in which the yield of red pepper fruits was highly correlated with the incidence of Phytophthora blight was different between areas: it was highly correlated in the third harvest in Cheongwon (y=-11.0x+435.2, r2= 0.99, but in the second harvest in Boeun (y=-15.0x+944.6, r2=0.76. In contrast, there was a very low correlation between the pepper yield and the disease incidence in Goesan in which pepper seedlings grafted on resistant stocks were planted. The final disease incidence in the Cheongwon experimental field reached 100% more than 40 days later in 2007 compared with that in 2006. The control threshold of Phytophthora blight in the pepper fields where disease incidence had been lower than 5% was set as 0.8% disease incidence, which caused less than 5% yield loss
Kessel, G.J.T.; Andersson, B.; Widmark, A.K.; Yuen, J.E.; Evenhuis, A.; Turkensteen, L.J.; Lehtinen, A.; Nielsen, B.; Ravnskov, S.; Hansen, J.G.; Hermansen, A.; Brurberg, M.B.; Nordskog, B.
Potato late blight (Phytophthora infestans) is a plant disease feared globally by farmers and the potato industry. P. infestans is a heterothallic oomycete with two mating types. Until recently the pathogen was limited to surviving between seasons as living mycelia in its host plant in most parts of
Fusarium head blight (FHB) of wheat is caused by numerous Fusarium species, including trichothecene-producers. In South Africa, FHB is mostly associated with irrigated wheat rotated with maize. Twenty symptomatic wheat heads were collected from four cultivars each in irrigated fields in the Northern...
Wheat ( Triticum aestivum L.) belongs to the three most important food crops in the world. In certain years, the crop can suffer considerable damage as a result of Fusarium Head Blight (FHB), especially as no chemical control is effective against
Pantoea agglomerans and P. vagans (ex. Erwinia herbicola) are common epiphytes of pome fruit flowers and three strains (E325, P10c, C9-1) have been commercially developed as effective biocontrol products for managing fire blight (Erwinia amylovora). Antibiotics as a standard, reliable chemical optio...
Schepers, H.T.A.M.; Gunadi, N.; Putter, de H.; Moekasan, T.K.; Prabaningrum, L.; Karjadi, A.K.
Demo plots with potato varieties Atlantic and Granola were laid out in Garut and Pangalengan from October 2014 to January 2015. The objective of the demo plots described in this report are to investigate the influence of three factors on the efficacy of three factors in late blight control
Thomas J. Molnar; John Capik; Clayton W. Leadbetter; Ning Zhang; Guohong Cai; Bradley I. Hillman
Eastern filbert blight (EFB) is a devastating fungal disease of European hazelnut, Corylus avellana L., and is considered to be the primary reason hazelnuts have not been developed as a commercial crop in the eastern United States. The pathogen, Anisogramma anomala, is native to a wide area east of the Rocky Mountains, where it...
This study evaluated the effect of two plant extracts, Ricinus communis and Chromolaena odorata on the control of the early blight pathogen, Alternaria solani (Ell. and Mart.). The study was conducted in the Laboratory of the Crop Production and Horticulture Department, Federal University of Technology, Yola, Adamawa ...
Flier, W.G.; Kessel, G.J.T.; Bosch, van den G.B.M.; Turkensteen, L.J.
A recent migration of a variable population of P. infestans has largely displaced the clonal A1 population in Western Europe. Sexual reproduction in European late blight populations is now possible and has been reported. The increased levels of aggressiveness form an important epidemiological
Liu, S. X.; Pumphrey, M. O.; Gill, B. S.; Trick, H. N.; Zhang, J. X.; Doležel, Jaroslav; Chalhoub, B.; Anderson, J. A.
Roč. 36, suppl. B (2008), s. 195-201 ISSN 0133-3720 Institutional research plan: CEZ:AV0Z50380511 Keywords : map-based cloning * Fusarium head blight * Fhb1 Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.190, year: 2007
Thomas L. Kubisiak; F.V. Hebard; C. Dana Nelson; Jiansu Zhang; R. Bernatzky; H. Huang; S.L. Anagnostakis; R.L. Doudrick
A three-generation American chestnut x Chinese chestnut pedigree was used to construct a genetic linkage map for chestnut and to investigate the control of resistance to Endothia parasitica (chestnut blight fungus). DNA genotypes for 241 polymorphic markers (eight isozymes, 17 restriction fragment length polymorphisms [RFLPs], and 216 random...
A Chinese Spring-Sumai 3 chromosome 7A disomic substitution line (CS-Sumai 3-7ADSL) was reported to have a high level of Fusarium head blight (FHB) resistance for symptom spread within a spike (Type II) and low deoxynivalenol accumulation in infected kernels (Type III), but quantitative trait locus ...
In this study we sequenced the genomes of 60 Fusarium graminearum, the major fungal pathogen responsible for Fusarium head blight (FHB) in cereal crops world-wide. To investigate adaptive evolution of FHB pathogens, we performed population-level analyses to characterize genomic structure, signatures...
Stacy L. Clark; Scott E. Schlarbaum; A.M. Saxton; Fred V. Hebard
The American chestnut (Castanea dentata Marsh. Borkh.) was decimated by an exotic fungus (chestnut blight [Cryphonectria parasitica Murr. Bar]) in the early part of the 20th century. The American Chestnut Foundation (TACF) uses a back-cross breeding program to produce a tree that is predicted to be American chestnut in character...
Zsolt Jakab- Ilyefalv
Full Text Available At Bistriţa Fruit Research and Development Station, in a pear collection, planted with 44 varieties, there has been studied the susceptibility to fire blight (Erwinia amylovora,Burill. During the vegetation period, phytosanitary treatments to control the disease have been applied using copper based products (copper sulfate, Champion, Funguran, Kocide. Erwinia amylovora infections have been influenced by the rainfall registered in April (70.9 mm and May (104.7 mm and the temperature fluctuations in April-May. The field observations on Erwinia amylvora attack demonstrate that the pear varieties have a different susceptibility to this dangerous bacterium. Evaluation of attack level in the pear collection was done using an evaluation scale with 9 scores using a reference resistance scale for : ‘Highly resistant’ , ‘Moderately resistant’, ‘Susceptible’, ‘Very susceptible’ cultivars . The most sensitive pear varieties in the collection were: ‘De Noiembrie’, ‘Abatele Fetel’, ’Daciana’, ’Triumf’, ’Williams Boway’, ’Margareta Marillat’, ’Beauty Tomme’, ‘Williams rosu’, ’Aromata de Bistrita’, ’Jeanne d`Arc’, ’Aramiu de Somes’, ’Belle des Arbres’, ’Zorka’ representing 13.64% of the total pear varieties. In several cultivars there have been observed increased symptoms, a very high susceptibility of infections leading to complete scorching of trees: Jeanne d`Arc’, Williams rosu’, ‘Triumf’, ‘Aromata de Bistrita’, ‘Zorka’. Strong attack symtoms were observed at the pear cultivars ‘Cure’, ‘Euras, ’Ciuda’ ‘Highland’, ‘Precoce Morettini’, ’Monica’, ’Cadillac’, ’Juliana’, ’Somesan’, ’Beurré Hardenpont’ these cultivars being susceptible to Erwinia amylovora , representing 40.91 % of total genotypes . Cultivars ‘Untoasa Geoagiu’, ‘Beurre Hardy’, ‘Trivale’ manifested a certain tolerance to Erwinia amylovora , no attack symptoms being
Full Text Available The effect of populin extract from black poplar (Populus nigra on late blight was assessed under laboratory and field conditions. The growth rate of hyphae was found to be significantly lower after 1v/v% populin application, and no hyphae growth was detected under 3 and 6v/v% populin application. Populin also reduced the light blight severity on potato leaves under field conditions. From our results, we have concluded that populin extract can be considered as a new and environmentally-friendly alternative for the control of late blight under field conditions.
The results of etiological studies on semimature-tissue needle blight (SNB) of eastern white pine (Pinus strobus L.) deny any role to needle fungi as the primary cause. No mycelium was found in newly blighted semimature tissue by either cultural or histological methods. Mycelia of several saprophytic fungi were isolated from the blighted portions of current year needles about 2 weeks after the onset of SNB, and fruit-bodies of different organisms were found to occur both in the interior and on the exterior of blighted needles about 4 weeks after the first occurrence of disease symptoms. The morphological development of apothecia of C. acuum was studied. Hysterothecia of Lophodermium spp. (L. pinastri (Schrad. ex Fr.) Chev. and L. nitens Darker) occurred ubiquitously on fallen white pine needles. Aerial spore trapping showed that ascospores of C. acuum were abundant, those of Lophodermium spp. were prevalent, and those of H. desmazierii were practically non-existent in the area investigated. There was little coincidence between the occurrence of SNB outbreaks and peak populations of air-borne ascospores of these fungi. Ascospore suspensions and needles bearing fructifications of C. acuum and Lophodermium spp. were used to inoculate the newly developing needles of SNB-susceptible and non-susceptible field trees and potted seedlings, but the typical symptoms of SNB did not develop as a result of these inoculations. Two fungicides, captan and Bordeaux mixture, were applied to SNB-susceptible and non-susceptible field trees throughout the growing season, but neither fungicide prevented the symptoms of SNB from appearing on the new needles of susceptible trees at the same time as they appeared on untreated susceptible trees in the area. The fungicidal sprays, however, did prevent saprophyttic fungi from invading blighted portions of the needles. It is concluded from this investigation that SNB is not a disease of fungal origin. 19 references, 17 figures, 3 tables.
Vonk, J.A.; Smulders, Fee O.H.; Christianen, Marjolijn J.A.; Govers, Laura L.
Knowledge on the role of seagrass leaf elements and in particular micronutrients and their ranges is limited. We present a global database, consisting of 1126 unique leaf values for ten elements, obtained from literature and unpublished data, spanning 25 different seagrass species from 28 countries.
Charles B. Briscoe; F. Bruce. Lamb
A study was made of the putative hybrid of bigleaf and small-leaf mahoganies. Initial measurements indicated that bigleaf mahogany can be distinguished from small-leaf mahogany by gross measurements of leaflets. Isolated mother trees yield typical progeny. Typical mother trees in mixed stands yield like progeny plus, usually, mediumleaf progeny. Mediumleaf mother trees...
Huynh Van Kiet
Full Text Available The 32R rice genotype is resistant to sheath blight disease (ShB, with a high-yield potential. We examined effects of temperature on the plant responses of 32R in comparison with those of the ShB-susceptible rice genotype (29S and Nipponbare (Nb, a Japonica standard cultivar. The seedlings at the 4th leaf stage of rice genotypes were exposed to 14/14, 19/14, 25/20, 31/26, 37/32 and 37/37 °C (day/night for 5, 10 and 15 days. The dry weight, leaf area, photosynthesis, contents of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco and chlorophyll contents were examined. The dry weight showed lower in 32R than in 29S and Nb at a low temperature, and total dry weight correlated strongly with root dry weight and leaf area. The relative growth rate (RGR correlated strongly with the net assimilation rate (NAR. Rubisco, chlorophyll contents and the photosynthetic rates were limited at a low temperature and showed lower in 32R than in 29S and Nb. The strong correlations between Rubisco and the rates of maximum photosynthesis and initial slope were found in 32R, but not found in 29S and Nb. In addition, RGR and NAR of 32R correlated positively with Rubisco. These suggest that 32R contains traits of cold-sensitive genotypes that are related to limiting Rubisco at a low temperature, thus diminishing photosynthesis and limiting plant growth. Differences of growth among 32R, 29S and Nb were discussed in the relation of genotypes.
Jastrab, Jordan B; Darwin, K Heran
Interest in bacterial proteasomes was sparked by the discovery that proteasomal degradation is required for the pathogenesis of Mycobacterium tuberculosis, one of the world's deadliest pathogens. Although bacterial proteasomes are structurally similar to their eukaryotic and archaeal homologs, there are key differences in their mechanisms of assembly, activation, and substrate targeting for degradation. In this article, we compare and contrast bacterial proteasomes with their archaeal and eukaryotic counterparts, and we discuss recent advances in our understanding of how bacterial proteasomes function to influence microbial physiology.
Jørgensen, Lise N; K. Nielsen, Linda; Nielsen, Bent J
Seedling blight caused by Fusarium spp. and Microdochium spp. is common on wheat grain, and severe attacks can lead to poor establishment of new crops. Several seed treatments using bitertanol, difenoconazole, triticonazole, maneb, fludioxonil or guazatine found to significantly control Fusarium...... seedling blight (Fusarium spp., Microdochium spp.) were improving germination and reducing seedling blight on roots and coleoptiles under field conditions in winter wheat. Some of the seed treatments were also shown to have an impact on soil-borne Fusarium in trials carried out under glasshouse conditions...... germination by approximately 100%, which led to an improved crop stand and yield increases in the range of 1.2–1.5 tonnes ha−1. Attacks of Fusarium head blight were relatively slight in the two trials and the content of deoxynivalenol was below the EU limits of 1250 ppb in the harvested grain. Even so, seed...
Loosdrecht, van M.C.M.
As mentioned in the introduction of this thesis bacterial adhesion has been studied from a variety of (mostly practice oriented) starting points. This has resulted in a range of widely divergent approaches. In order to elucidate general principles in bacterial adhesion phenomena, we felt it
Full Text Available Objective: To determine antibacterial activity of water, oil and methanol extracts of guava (Psidium guajava, green tea (Camellia sinensis, neem (Azadirachta indica and marigold (Calendula officinalis against different species of bacteria, Pseudomonas spp., Vibrio cholerae, Vibrio parahaemolyticus (V. parahaemolyticus, Klebsiella spp., Escherichia coli, Salmonella spp. and Staphylococcus aureus (S. aureus. Methods: Antibacterial activity of plant extracts was measured by agar well diffusion method. Results: Boiled water extracts of guava leaf showed the largest zone of inhibition (22 mm against V. parahaemolyticus. Water extracts of green tea leaf at boiling and room temperature showed 17.5 mm and 19 mm zone of inhibitions against V. parahaemolyticus and S. aureus, respectively. Boiled water extract of neem leaf showed moderate zone of inhibition against Escherichia coli (10 mm and Klebsiella spp. (11 mm. Water and oil extracts of marigold leaf at both boiling and room temperature did not show any zone of inhibition against any of the tested microorganisms. Methanol extracts of both guava and green tea leaves showed same zone of inhibition against Pseudomonus spp. (18 mm. Methanol extract of neem leaf showed antibacterial acitivity against Klebsiella spp. (16 mm and Vibrio cholerae (14 mm and that of marigold leaf showed antimicrobial activity against S. aureus (18 mm and Klebsiella spp. (12 mm. Conclusions: The results from the study suggest that the leaves of guava, green tea, neem and marigold show anibacterial activity against different bacterial species. They could be used as alternatives to common antimicrobial agents for treatment of bacterial infections.
Colletotrichum spp. are causal agents of anthracnose in many plant species. Biological control of Colletotrichum spp. utilizing bacterial isolates and fungi has been reported. However, chitinolytic bacterial isolate utilization to control anthracnose of cocoa leaf has not seemingly been studied yet. In this study, we used ...
There has been increasing prevalence of bacterial resistance to commonly used antibiotics. The present study investigates the synergistic action of Ageratum conyzoides leaf extracts and antibiotics against Pseudomonas aeruginosa and Staphylococcus aureus isolated from wounds. The disc diffusion method was used.
José Fernando Jurca Grigolli
Full Text Available The purpose of this study was to characterize 50 tomato genotypes of the Vegetable Genebank of the FederalUniversity of Viçosa. They were evaluated together with the controls Débora, Fanny and Santa Clara, in a randomized block designwith two replications. The experiment was conducted in a research field of the UFV, from February to May 2007. We evaluated thedisease severity, which is the percentage of diseased leaf area. The severity values were transformed into area under the diseaseprogress curve (AUDPC, improving the result visualization. The analysis of variance and grouping of AUDPC means by the Scott-Knott test at 5 % significance were performed. The accessions BGH-2081, BGH-2034, BGH-700, BGH-2057, BGH-2035, BGH-2054, BGH-2018, BGH-2065, BGH-2008, and BGH-2032 had a lower mean AUDPC than the controls and are therefore indicatedfor future breeding programs.
Born, Yannick; Fieseler, Lars; Thöny, Valentin; Leimer, Nadja; Duffy, Brion; Loessner, Martin J
Erwinia amylovora is the causative agent of fire blight, a devastating plant disease affecting members of the Rosaceae Alternatives to antibiotics for control of fire blight symptoms and outbreaks are highly desirable, due to increasing drug resistance and tight regulatory restrictions. Moreover, the available diagnostic methods either lack sensitivity, lack speed, or are unable to discriminate between live and dead bacteria. Owing to their extreme biological specificity, bacteriophages are promising alternatives for both aims. In this study, the virulent broad-host-range E. amylovora virus Y2 was engineered to enhance its killing activity and for use as a luciferase reporter phage, respectively. Toward these aims, a depolymerase gene of E. amylovora virus L1 ( dpoL1-C ) or a bacterial luxAB fusion was introduced into the genome of Y2 by homologous recombination. The genes were placed downstream of the major capsid protein orf68 , under the control of the native promoter. The modifications did not affect viability of infectivity of the recombinant viruses. Phage Y2:: dpoL1-C demonstrated synergistic activity between the depolymerase degrading the exopolysaccharide capsule and phage infection, which greatly enhanced bacterial killing. It also significantly reduced the ability of E. amylovora to colonize the surface of detached flowers. The reporter phage Y2:: luxAB transduced bacterial luciferase into host cells and induced synthesis of large amounts of a LuxAB luciferase fusion. After the addition of aldehyde substrate, bioluminescence could be readily monitored, and this enabled rapid and specific detection of low numbers of viable bacteria, without enrichment, both in vitro and in plant material. IMPORTANCE Fire blight, caused by Erwinia amylovora , is the major threat to global pome fruit production, with high economic losses every year. Bacteriophages represent promising alternatives to not only control the disease, but also for rapid diagnostics. To enhance
Mizobuchi, Ritsuko; Fukuoka, Shuichi; Tsushima, Seiya; Yano, Masahiro; Sato, Hiroyuki
In rice (Oryza sativa L.), damage from diseases such as brown spot, caused by Bipolaris oryzae, and bacterial seedling rot and bacterial grain rot, caused by Burkholderia glumae, has increased under global warming because the optimal temperature ranges for growth of these pathogens are relatively high (around 30 °C). Therefore, the need for cultivars carrying genes for resistance to these diseases is increasing to ensure sustainable rice production. In contrast to the situation for other important rice diseases such as blast and bacterial blight, no genes for complete resistance to brown spot, bacterial seedling rot or bacterial grain rot have yet been discovered. Thus, rice breeders have to use partial resistance, which is largely influenced by environmental conditions. Recent progress in molecular genetics and improvement of evaluation methods for disease resistance have facilitated detection of quantitative trait loci (QTLs) associated with resistance. In this review, we summarize the results of worldwide screening for cultivars with resistance to brown spot, bacterial seedling rot and bacterial grain rot and we discuss the identification of QTLs conferring resistance to these diseases in order to provide useful information for rice breeding programs.
The Imperial Instituto Fluminense de Cultura (Fluminense Imperial Institute of Agriculture) encouraged debate with a view to eradicating the blight that devastated sugar cane plantations in the State of Bahia. Rural landowners, government officials and men of science participated in the discussions. The article presents the context of the sciences applied to agriculture, especially agricultural chemistry and the repercussions of the 'discoveries' of Justus Liebig in Brazil. The debate at the Imperial Instituto about the sugar cane blight was analyzed, together with the ideas espoused there and the characters involved in the issue. The procedures and solutions presented are studied, as well as the formation of knowledge networks around the agricultural sciences, which was in the process of institutionalization at the time.
Søltoft, Malene; Jørgensen, Lise N.; Svensmark, Bo
Fusarium Head Blight (FHB) is a destructive disease that affects the grain yield and quality of cereals. The relationship between the natural defense chemicals benzoxazinoids and the FHB resistance of field grown winter wheat varieties was investigated. FHB resistance was assessed by the inoculat......Fusarium Head Blight (FHB) is a destructive disease that affects the grain yield and quality of cereals. The relationship between the natural defense chemicals benzoxazinoids and the FHB resistance of field grown winter wheat varieties was investigated. FHB resistance was assessed......,4-benzoxazin-3(4H)-one (HMBOA, 2.0-11 mu mol/kg DW). The cultivars most susceptible to FHB were cvs. Hanseat, Asketis, and Ritmo, while cvs. Petrus, Terra, and Hattrick showed high resistance. 2-O-beta-D-Glucopyranosyloxy-4,7-dimethoxy-(2H)-1,4-benzoxazin-3(4H)-one (HMBOA-glc) and 2-O...
Šterbik Ildiko R.
Full Text Available Effect of fungicide treatments on Fusarium head blight (FHB and grain yield of wheat depending on application technique i.e. use of different nozzle types, was evaluated in the study. Nozzles types TJ 11004, Albuz ATR 8004 and Arag TFA 11004 were used for application of systemic fungicide Duett Ultra (0.5 l/ha. FHB intensity (% was determined on the basis of a visual assessment of the number of infected heads and the perecentage of the disease symptoms on the individual head. Differences in grain yield between the treated variants, as well as between the treated and untreated variants, were determined after hand threshing. The lowest percentage of FHB development in wheat and the highest yield were recorded in variants where fungicides were applied by nozzle type ATR 8004. Application technique directly affects the reduction of fusarium head blight in wheat and indirectly it also reduces yield loss.
Henning, Jeremiah A.; Weston, David J.; Pelletier, Dale A.
phenotype. We chose three bacterial strains that differed in predicted metabolic capabilities, plant hormone production and metabolism, and secondary metabolite synthesis. We inoculated each bacterial strain on a single genotype of Populus trichocarpa and measured the response of plant growth related traits......Plant traits, such as root and leaf area, influence how plants interact with their environment and the diverse microbiota living within plants can influence plant morphology and physiology. Here, we explored how three bacterial strains isolated from the Populus root microbiome, influenced plant...... (root:shoot, biomass production, root and leaf growth rates) and physiological traits (chlorophyll content, net photosynthesis, net photosynthesis at saturating light-Asat, and saturating CO2-Amax). Overall, we found that bacterial root endophyte infection increased root growth rate up to 184% and leaf...
E. Richard Toole; W. M. Broadfoot
A BLIGHT OF UNKNOWN origin and cause has been very common throughout much of the range of sweetgum (Liquidambar styraci flua L.) since 1950. It is characterized by a gradual dying of the tree, often from the top down. The first visible indication is a thinning of a portion of the crown, caused when some buds fail to open and others produce only dwarfed, yellowish...
LOUISE LARISSA MAY DE MIO
Full Text Available Persimmon anthracnose has been a great concern to Brazilian producers. This study aimed to identify and characterized the causal species from Brazilian persimmons byassessing morphological and molecular characteristics and pathogenicity tests. Five fungal isolatesobtained from diseased twigs and fruits were identified as Colletotrichum horii, based on morphologicalcharacteristics and nucleotide sequences of ITS region. Inoculation tests revealed that the fungal isolates caused necrotic spots followed by defoliation of leaves, blight of twigs and buds of potted persimmon plants.
Salomone-Stagni, Marco; Bartho, Joseph D; Polsinelli, Ivan; Bellini, Dom; Walsh, Martin A; Demitri, Nicola; Benini, Stefano
The Gram-negative bacterium Erwinia amylovora is the etiological agent of fire blight, a devastating disease which affects Rosaceae such as apple, pear and quince. The siderophore desferrioxamine E plays an important role in bacterial pathogenesis by scavenging iron from the host. DfoJ, DfoA and DfoC are the enzymes responsible for desferrioxamine production starting from lysine. We have determined the crystal structures of each enzyme in the desferrioxamine E pathway and demonstrate that the biosynthesis involves the concerted action of DfoJ, followed by DfoA and lastly DfoC. These data provide the first crystal structures of a Group II pyridoxal-dependent lysine decarboxylase, a cadaverine monooxygenase and a desferrioxamine synthetase. DfoJ is a homodimer made up of three domains. Each monomer contributes to the completion of the active site, which is positioned at the dimer interface. DfoA is the first structure of a cadaverine monooxygenase. It forms homotetramers whose subunits are built by two domains: one for FAD and one for NADP + binding, the latter of which is formed by two subdomains. We propose a model for substrate binding and the role of residues 43-47 as gate keepers for FAD binding and the role of Arg97 in cofactors turnover. DfoC is the first structure of a desferrioxamine synthetase and the first of a multi-enzyme siderophore synthetase coupling an acyltransferase domain with a Non-Ribosomal Peptide Synthetase (NRPS)-Independent Siderophore domain (NIS). Copyright © 2018 Elsevier Inc. All rights reserved.
... Archive STDs Home Page Bacterial Vaginosis (BV) Chlamydia Gonorrhea Genital Herpes Hepatitis HIV/AIDS & STDs Human Papillomavirus ( ... of getting other STDs, such as chlamydia and gonorrhea . These bacteria can sometimes cause pelvic inflammatory disease ( ...
Full Text Available Dothistroma needle blight Mycosphaerella pini E. Rostrup resp. its anamorphic stage Dothistroma septospora (Dorog. Morelet was for the first time noted in the region of the Czech Republic in a consignment of imported plants of Austrian pine Pinus nigra Arnold in 1999. In 2000, it was also found on Pinus nigra in an open planting in a plantation of Christmas trees near the village of Jedovnice by Brno in the South Moravia. In the Czech Republic, Dothistroma needle blight was identified on 19 species of pines and 5 species of spruces. The critical period for infection is in the Czech Republic from the second half of May until the end of June, when the new shoots and needles develop. The incubation period lasts about 2–4 months depending on climatic conditions. The first symptoms on the needles infected in the current year appear in August being clearly expressed from September to November. In the CR, Dothistroma needle blight spread probably with infected planting stock obtained from import at the end of the 80s and at the beginning of the 90s.
Hu, Yao-hua; Ping, Xue-wen; Xu, Ming-zhu; Shan, Wei-xing; He, Yong
Hyperspectral imaging feature on potato leaves stressed by late blight was studied in the present paper. The experiment used 60 potato leaves. Among those 60 potato leaves, 48 leaves were vitro inoculated with pathogen of potato late blight, the rest 12 leaves were used as control samples. The leaves were observed for 7 continuous days before and after inoculated and samples including healthy and infested were acquired. Hyperspectral data of healthy and infected potato samples of different disease severity were obtained by the hyperspectral imaging system from 374 to 1,018 nm and then extract spectral data of region of interest (ROI) from those hyperspectral data by the ENVI software. In order to improve the signal-to-noise ratio, the spectral data were preprocessed using different pretreatment methods such as moving average smoothing, normalization, derivative, baseline etc. The least squares-support vector machine(LS-SVM) models were developed based on the raw and those preprocessed data. Among the nine models, the model that used the raw data and the data after the spectroscopic transformation performed best with the discrimination of 94.87%. It was demonstrated that it is realized to determine the potato late blight disease of different disease severity using hyperspectral imaging technique.
Erlei Melo Reis
Full Text Available ABSTRACT Fusarium head blight of wheat (Triticum aestivum, caused by the fungus Gibberella zeae, is a floral infecting disease that causes quantitative and qualitative losses to winter cereals. In Brazil, the sanitary situation of wheat has led to research in order to develop strategies for sustainable production, even under adverse weather conditions. To increase the knowledge of the relationship among the presence of anthesis, the infectious process, the disease progress and the saprophytic fungi present in wheat anthers, studies were conducted in the experimental field of University of Passo Fundo (UPF, using the cultivar Marfim, in the 2011 growing season. The disease incidence in spikes and spikelets was evaluated. The presence of exserted anthers increased the spike exposure time to the inoculum. The final incidence of fusarium head blight, in the field, was dependent on the presence of exserted anthers. The disease followed an aggregation pattern and its evolution increased with time, apparently showing growth according to secondary cycles. The fungi isolated from exserted anthers (Alternaria sp., Fusarium sp., Drechslera spp. and Epicoccum sp. did not compete for the infection site of fusarium head blight in wheat, not interfering with the incidence of F. graminearum.
Ji, Pingsheng; Koné, Daouda; Yin, Jingfang; Jackson, Kimberly L; Csinos, Alexander S
Phytophthora blight induced by Phytophthora capsici is responsible for serious yield loss in vegetable production in the United States and other countries. This study was conducted to evaluate the efficacy of Brassica cover crops used as soil amendments for managing Phytophthora blight of squash. In greenhouse studies, disease incidence on squash plants was significantly reduced by soil amendment with mustard shoots or roots used at 1 and 2.5% (plant tissue/soil, w/w). The shoots of canola used at 1 or 2.5% also suppressed disease, while the roots of canola or other crops did not reduce disease significantly. In field studies, soil amendments with mustard and canola provided the greatest disease reduction and increased squash yield significantly compared with the non-treated control. Mustard and canola did not appear to be susceptible to P. capsici. The results indicated that some Brassica crops, particularly mustard and canola, had the potential to significantly reduce Phytophthora blight on squash when used as soil amendments. As P. capsici has a remarkable ability to develop resistance to chemical fungicides, use of effective Brassica cover crops could be a biorational alternative to fungicides and a valuable component in developing integrated disease management programs. Copyright © 2011 Society of Chemical Industry.
Peng, Di; Li, Shandong; Wang, Jianxin; Chen, Changjun; Zhou, Mingguo
Sheath blight caused by Rhizoctonia solani Kühn is a major disease of rice that greatly reduces yield and grain quality and jinggangmycin is the most widely used fungicide to control this disease in China. Bacillus subtilis NJ-18 has broad antimicrobial activity to many phytopathogenic bacteria and fungi; it is especially effective against Rhizoctonia solani. Laboratory, greenhouse and field tests were conducted to determine the effect of combining the biological control agent Bacillus subtilis NJ-18 with the fungicide jinggangmycin for control of rice sheath blight. Growth of NJ-18 in vitro was not affected by jinggangmycin. In a greenhouse experiment, disease control was greater with a mixture of NJ-18 and jinggangmycin than with either alone; a mixture of NJ-18 at 10(8) cfu mL(-1) and jinggangmycin at 50 or 100 mg L(-1) reduced lesion length by 35% and 20%, respectively, and the combinations showed a synergistic action. In three field trials, disease control was significantly greater with a mixture of NJ-18 at 10(8) cfu mL(-1) and jinggangmycin at 75 or 150 g a.i. ha(-1) than with either component alone. The results of the study indicate that, when Bacillus subtilis NJ-18 strain was combined with jinggangmycin, there was an increased suppression of rice sheath blight, and thus could provide an alternative disease control option. © 2013 Society of Chemical Industry.
Schaefer, Scott C; Gasic, Ksenija; Cammue, Bruno; Broekaert, Willem; van Damme, Els J M; Peumans, Willy J; Korban, Schuyler S
Genes coding for an iris ribosomal-inactivating protein (I-RIP), a maize beta-glucanase (M-GLU), and a Mirabilis jalapa antimicrobial peptide (Mj-AMP1) were separately introduced into tomato (Lycopersicon esculentum cv. Sweet Chelsea) cotyledons via Agrobacterium tumefaciens-mediated transformation. Transgenic lines carrying each of the transgenes were confirmed for integration into the tomato genome using Southern blot hybridization. Transcription of I-RIP, M-GLU, and Mj-AMP1 genes in various transgenic lines was determined using Northern blot analysis. Plants of selected transgenic lines were inoculated with a 2-3x10(4) conidial spores/ml suspension of the fungal pathogen Alternaria solani, the causal agent of tomato early blight. Compared to control (non-transformed) plants, two transgenic lines carrying either a M-GLU or Mj-AMP1 showed enhanced resistance to early blight disease. None of the four lines carrying the I-RIP transgene showed increased resistance to early blight.
Full Text Available The present study was performed to evaluate antifungal activities of leaf essential oils from Eucalyptus camaldulensis Dehnh. originating from Thailand against 9 fungal strains. The leaf samples were collected from 3 different clones. The fungi examined in this study were (1 household molds: Aspergillus niger , Cladosporium cladosporioides, Chaetomium globosum and Penicillium citrinum, (2 wood rot fungi: Fomitopsis palustris and Trametes versicolor, (3 plant pathogenic fungi: Fusarium oxysporum, Thanatephorus cucumeris and Rhizopus oryzae. The results revealed that E. camaldulensis leaf oils provided 100% inhibition of the mycelial growth of T. cucumeris (5 mg/m L , and C. globosum (10 mg/m L . No inhibition effect was observed against R. oryzae even at the concentration of 10 mg/m L . A medium to low inhibitory activities against the mycelial growth of the six other fungi were found. The essential oils of E. camaldulensis leaf have potency as an antimicrobial agent especially against seedling blight pathogens and it could also act as moderate agents against household molds and wood rot fungi. Therefore, even if they need relatively higher concentration for the controlling agents, they deserve as the alternatives to hazardous synthetic fungicides from the ecological viewpoints.
Singh, H Ranjit; Deka, Manab; Das, Sudripta
Tea is the second most consumed beverage in the world. A crop loss of up to 43 % has been reported due to blister blight disease of tea caused by a fungus, Exobasidium vexans. Thus, it directly affects the tea industry qualitatively and quantitatively. Solanum tuberosum class I chitinase gene (AF153195) is a plant pathogenesis-related gene. It was introduced into tea genome via Agrobacterium-mediated transformation with hygromycin phosphotransferase (hpt) gene conferring hygromycin resistance as plant selectable marker. A total of 41 hygromycin resistant plantlets were obtained, and PCR analysis established 12 plantlets confirming about the stable integration of transgene in the plant genome. Real-time PCR detected transgene expression in four transgenic plantlets (T28, C57, C9, and T31). Resistance to biotrophic fungal pathogen, E. vexans, was tested by detached leaf infection assay of greenhouse acclimated plantlets. An inhibitory activity against the fungal pathogen was evident from the detached leaves from the transformants compared with the control. Fungal lesion formed on control plantlet whereas the transgenic plantlets showed resistance to inoculated fungal pathogen by the formation of hypersensitivity reaction area. This result suggests that constitutive expression of the potato class I chitinase gene can be exploited to improve resistance to fungal pathogen, E. vexans, in economical perennial plantation crop like tea.
Ramsey, G.R.; Lorbeer, J.W.
The cardinal temperatures at which onion umbels were blighted (after inoculation when two-thirds of the florets were open) with Botrytis squamosa, B. cinerea, and B. allii (isolated from blighted onion florets) were near 9, 21, and 27 C for B. squamosa, near 12, 21, and 30 C for B. cinerea, and near 9, 24, and 30 C for B. allii. The cardinal temperatures for mycelial growth (potato-dextrose agar) of B. squamosa, B. cinerea, and B. allii were near 5, 22, and 30 C for each fungus. The cardinal temperatures for conidial germination (on purified water agar) were near 6, 15, and 30 C for B. squamosa; 3, 18, and 33 C for B. cinerea; and 6, 24, and 33 C for B. allii. When the duration of free moisture on umbels after inoculation with the three pathogens was increased from 0 to 96 hr. the percentages of unopened florets, open florets, and immature seed capsules blighted at 21 C were increased significantly. Free moisture durations of 12-24, 6-12, and 6-12 hr were necessary for blighting of unopen florets, open florets, and immature seed capsules, respectively, by each pathogen at 21 C. A positive correlation between the amount of July rainfall and the natural incidence of onion flower blight was observed in Orange County, New York, from 1976 to 1981. 10 references, 2 figures, 1 table.
Full Text Available Petroleum aromatic hydrocarbons like benzen e, toluene, ethyl benzene and xylene, together known as BTEX, has almost the same chemical structure. These aromatic hydrocarbons are released as pollutants in th e environment. This work was taken up to develop a solvent tolerant bacterial cons ortium that could degrade BTEX compounds as they all share a common chemical structure. We have isolated almost 60 different types of bacterial strains from different petroleum contaminated sites. Of these 60 bacterial strains almost 20 microorganisms were screene d on the basis of capability to tolerate high concentration of BTEX. Ten differe nt consortia were prepared and the compatibility of the bacterial strains within the consortia was checked by gram staining and BTEX tolerance level. Four successful mi crobial consortia were selected in which all the bacterial strains concomitantly grew in presence of high concentration of BTEX (10% of toluene, 10% of benzene 5% ethyl benzene and 1% xylene. Consortium #2 showed the highest growth rate in pr esence of BTEX. Degradation of BTEX by consortium #2 was monitored for 5 days by gradual decrease in the volume of the solvents. The maximum reduction observed wa s 85% in 5 days. Gas chromatography results also reveal that could completely degrade benzene and ethyl benzene within 48 hours. Almost 90% degradation of toluene and xylene in 48 hours was exhibited by consortium #2. It could also tolerate and degrade many industrial solvents such as chloroform, DMSO, acetonitrile having a wide range of log P values (0.03–3.1. Degradation of aromatic hydrocarbon like BTEX by a solvent tolerant bacterial consortium is greatly significant as it could degrade high concentration of pollutants compared to a bacterium and also reduces the time span of degradation.
Han, Jae Woo; Shim, Sang Hee; Jang, Kyoung Soo; Choi, Yong Ho; Dang, Quang Le; Kim, Hun; Choi, Gyung Ja
As an alternative to synthetic pesticides, natural materials such as plant extracts and microbes have been considered to control plant diseases. In this study, methanol extracts of 120 plants were explored for in vivo antifungal activity against Rhizoctonia solani, Botrytis cinerea, Phytophthora infestans, Puccinia triticina, and Blumeria graminis f. sp. hordei. Of the 120 plant extracts, eight plant extracts exhibited a disease control efficacy of more than 90% against at least one of five plant diseases. In particular, a methanol extract of Curcuma zedoaria rhizomes exhibited strong activity against wheat leaf rust caused by P. triticina. When the C. zedoaria methanol extracts were partitioned with various solvents, the layers of n-hexane, methylene chloride, and ethyl acetate showed disease control values of 100, 80, and 43%, respectively, against wheat leaf rust. From the C. zedoaria rhizome extracts, an antifungal substance was isolated and identified as a sesquiterpene ketolactone based on the mass and nuclear magnetic resonance spectral data. The active compound controlled the development of rice sheath blight, wheat leaf rust, and tomato late blight. Considering the in vivo antifungal activities of the sesquiterpene ketolactone and the C. zedoaria extracts, these results suggest that C. zedoaria can be used as a potent fungicide in organic agriculture.
Berkhoff, Arthur P.; Lemmen, Remco Louis Christiaan
The invention relates to a leaf spring for an electromagnetic actuator and to such an electromagnetic actuator. The leaf spring is formed as a whole from a disc of plate-shaped, resilient material. The leaf spring comprises a central fastening part, an outer fastening part extending therearound and
Soil and irrigation management have been used to optimize crop production; however,their effects on microclimate, development, and potato diseases have not been adequately quantified. The effects of soil, crop, and water management on development of potato early blight and late blight were quantifie...
Aßmann, Christine; Rinke, Karsten; Nechwatal, Jan; Elert, Eric von
1. Leaf litter breakdown by shredders in the field is affected by leaf toughness, nutritional value and the presence of secondary compounds such as polyphenols. However, experiments involving the use of single fungal strains have not supported the assumption that leaf parameters determine food selection by shredders perhaps because of a failure to test for high consumption prior to isolation of fungal strains, overrepresentation of hyphomycetes or the potential effects of accompanying bacteri...
Bacterial ecology is concerned with the interactions between bacteria and their biological and nonbiological environments and with the role of bacteria in biogeochemical element cycling. Many fundamental properties of bacteria are consequences of their small size. Thus, they can efficiently exploit...
Heckenberg, Sebastiaan G. B.; Brouwer, Matthijs C.; van de Beek, Diederik
Bacterial meningitis is a neurologic emergency. Vaccination against common pathogens has decreased the burden of disease. Early diagnosis and rapid initiation of empiric antimicrobial and adjunctive therapy are vital. Therapy should be initiated as soon as blood cultures have been obtained,
Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno
Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation,
, the production and oxidation of methane, nitrate reduction and fixation of atmospheric nitrogen are exclusively carried out by different groups of bacteria. Some bacterial species – ‘extremophiles’ – thrive in extreme environments in which no eukaryotic organisms can survive with respect to temperature, salinity...
... that coats the walls of the vagina Vaginal discharge with an unpleasant or fishlike odor Vaginal pain or itching Burning during urination Doctors are unsure of the incubation period for bacterial vaginosis. How Is the Diagnosis Made? Your child’s pediatrician can make the diagnosis ...
First page Back Continue Last page Graphics. Bacterial stress. Physicochemical and chemical parameters: temperature, pressure, pH, salt concentration, oxygen, irradiation. Nutritional depravation: nutrient starvation, water shortage. Toxic compounds: Antibiotics, heavy metals, toxins, mutagens. Interactions with other cells: ...
Dec 19, 2011 ... Effects of calcium, potassium and magnesium on oxalic, malic and citric acid content of Valencia orange leaf tissue. Plant Physiol. 36: 39-101. Ruffner HP, Possner D, Brem S, Rast DM (1984). The physiological role of malic enzyme in grape ripening. Plant, 160: 444-448. Sadka A, Artzi B, Cohen L, Dahan E ...
Gil Rodrigues dos Santos
Full Text Available Face à importância do crestamento gomoso do caule e à escassez de relatos da reação de genótipos de melancia na literatura nacional e internacional, este trabalho teve por objetivo avaliar a resposta de genótipos comerciais de melancia ao crestamento gomoso. No campo, estudou-se o nível de infecção nas folhas em delineamento de blocos ao acaso com nove cultivares de melancia e quatro repetições, com inoculação de duas plantas por parcela aos 43 dias após o plantio (DAP. Foram avaliadas as cultivares Crimson Sweet, Onix, Rubi, Safira, Eureka, Georgia, Sheila, Savana e Riviera. Em casa de vegetação, estudou-se a infecção no caule em vasos, com delineamento inteiramente casualizado, com três repetições, em esquema fatorial de 9 x 3, sendo o fator "a" = cultivares e o fator "b" = isolados. Foram avaliadas as mesmas cultivares do ensaio de campo, com inoculação artificial com disco de micélio aos 15 dias após a semeadura, quando do surgimento da primeira folha definitiva. Os isolados de D. bryoniae utilizados na inoculação das plântulas foram: UnB 76 (Melão-DF, UnB 75 (Melancia-PE e UnB 81 (Abóbora-DF. Dentre as cultivares avaliadas no campo, Riviera mostrou-se mais resistente e apresentou menores (PGummy stem blight, caused by Didymella bryoniae, is one of the most important watermelon diseases. Nevertheless, there are relatively few published studies on the response of watermelon genotypes to the disease. This paper reports results of studies on the response of commercially available watermelon cultivars to gummy stem blight. Leaf infection was studied in a randomized complete block field experiment with nine watermelon genotypes and four replicates. Two plants per experimental plot were inoculated 43 days after planting. Cultivars Crimson Sweet, Onix, Rubi, Safira, Eureka, Georgia, Sheila, Savana and Riviera were evaluated. Stem infection was studied in the greenhouse, in a completely randomized design, with three
Vejborg, Rebecca Munk
reduce or delay bacterial biofilm formation of a range of urinary tract infectious E.coli and Klebsiella isolates. Several other proteinaceous coatings were also found to display anti-adhesive properties, possibly providing a measure for controlling the colonization of implant materials. Several other...... components. These substances may both mediate and stabilize the bacterial biofilm. Finally, several adhesive structures were examined, and a novel physiological biofilm phenotype in E.coli biofilms was characterized, namely cell chain formation. The autotransporter protein, antigen 43, was implicated...
Penjkin Roman V.
Full Text Available Early blight of potato (the agent is imperfect fungus Alternaria alternata (Fr. Keissl. is a serious disease of potatoes under hot conditions. This disease is important in the regions of Eastern and Southern Europe, Asia and Africa. It is controlled with intensive application of fungicides commonly used against late blight. However, currently fungicides cause undesirable damage to humans and the environment. Elements of forecasting the early blight have been developed in order to minimize the dosage of fungicides. Primary symptoms (chloroses and necroses and the potential of pathogen natural inoculum (determination of disease severity, indexes of formation of conidia and aggressiveness; as well as the current weather conditions were registered and determined in the potato signal plots (no treatments or artificial inoculation near main potato cropping. Seed tubers of main potato cropping were preliminary treated with plant growth regulator Circon and micro-fertilizer Siliplant produced by the Russian Company NEST-M. These preparations proved to be effective in acceleration process of potato growth and in delaying the early blight onset by 5-10 days. The same potato cultivar must be planted both in signaling plots and in the fields. Well-timed determination of primary symptoms and potential of pathogen inoculum allowed us to understand the damage that early blight can cause to potato natural inoculation, and hence to provide well-timed application of fungicides with optimum dosages in mixture with Circon or Silipant. This forecasting method can be helpful for the adequate management of early blight and decrease of the environmental damages.
Thomas D Kost
Full Text Available The generation and selection of novel fire blight resistant apple genotypes would greatly improve the management of this devastating disease, caused by Erwinia amylovora. Such resistant genotypes are currently developed by conventional breeding, but novel breeding technologies including cisgenesis could be an alternative approach. A cisgenic apple line C44.4.146 was regenerated using the cisgene FB_MR5 from wild apple Malus ×robusta 5 (Mr5, and the previously established method involving A. tumefaciens-mediated transformation of the fire blight susceptible cultivar 'Gala Galaxy' using the binary vector p9-Dao-FLPi. The line C44.4.146 was shown to carry only the cisgene FB_MR5, controlled by its native regulatory sequences and no transgenes were detected by PCR or Southern blot following heat induced recombinase-mediated elimination of the selectable markers. Although this line contains up to 452 bp of vector sequences, it still matches the original definition of cisgenesis. A single insertion of T-DNA into the genome of 'Gala Galaxy' in chromosome 16 was identified. Transcription of FB_MR5 in line C44.4.146 was similar to the transcription in classically bred descendants of Mr5. Three independent shoot inoculation experiments with a Mr5 avirulent strain of Erwinia amylovora were performed using scissors or syringe. Significantly lower disease symptoms were detected on shoots of the cisgenic line compared to those of untransformed 'Gala Galaxy'. Despite the fact that the pathogen can overcome this resistance by a single nucleotide mutation, this is, to our knowledge, the first prototype of a cisgenic apple with increased resistance to fire blight.
P. E. V. Aguiar
Full Text Available Mato Grosso is the third largest producer of bean from Brazil, being the third harvest (irrigated the most productive, but diseases such as anthracnose, web blight and nematodes of galls cause losses to producers. In addition, a measure widely used and little studied for the control of diseases and nematodes in Mato Grosso is the biological control, which consists of the action of other microorganisms on phytopathogens. Thus, the objective of the present study was to evaluate the effect of Trichoderma harzianum and T. asperellum in the development (height of plants, chlorophyll and number of pods of culture of bean, in the control of anthracnose (Colletotrichum lindemuthianum, web blight (Rhizoctonia solani and in the population of Meloidogyne spp. in the soil. The experiment was accomplished in area experimental of University Federal of Mato Grosso/Campus Sinop. The experimental design was of entirely randomized with 12 parcels of 5m² each, with 3 treatments and 4 replications. The cultivar used was Whitey, carioca group, and the seed treatment performed with product Pyraclostrobin + Thiophanate Methyl + Fipronil and after drying of the inoculation of biocontrol agents and manual seeding. It was observed that the application of T. harzianum and T. asperellum, not promoted increase of chlorophyll, height of plants in bean culture, without reducing the population of Meloidogyne spp.. However, biocontrol agents have reduced the severity of anthracnose and web blight and promoted an increase in the average number of plant pods-1. It is therefore concluded that biocontrol agents show potential for application in bean culture in the North of Mato Grosso.
Walter, Stephanie; Nicholson, Paul; Doohan, Fiona M
The Fusarium species Fusarium graminearum and Fusarium culmorum, Which are responsible for Fusarium head blight (FHB) disease, reduced world-wide cereal crop yield and, as a consequence of their mycotoxin production in cereal grain, impact on both human and animal health. Their study is greatly...... involved in Fusarium infection, penetration and colonization of host tissues, and host avoidance thereof. This reviewer Illuminate and Integrates emerging knowledge regarding the molecular crosstalk between Fusarium and its small-grain cereal hosts. An understanding of the complexity of the host......-pathogen interactions will be instrumental in designing new efficient strategies for the control of FHB disease....
Rasmussen, Peter Have; Knudsen, I.; Elmholt, S.
the Hanes-Wolf transformation of the Michaelis-Menten equation. Soil samples from 6 to 13 cm depth were collected in the early spring as undisturbed blocks from 10 arable soils with different physico-chemical properties and cultivation history. Significant correlations were found between soil suppresiveness....... From the preliminary results obtained, it is proposed that the cellulolytic activity can be used as an enzymatic approach to study the microbial turnover of organic matter in soils and as indicator of seedling blight of barley caused by F. culmorum. (C) 2002 Elsevier Science B.V. All rights reserved....
Jing, Hai-Chun; Sturre, Marcel J.G.; Hille, Jacques; Dijkwel, Paul P.
The onset of leaf senescence is controlled by leaf age and ethylene can promote leaf senescence within a specific age window. We exploited the interaction between leaf age and ethylene and isolated mutants with altered leaf senescence that are named as onset of leaf death (old) mutants. Early leaf
Jaeger, Karl-Erich; Ransac, Stéphane; Dijkstra, Bauke W.; Colson, Charles; Heuvel, Margreet van; Misset, Onno
Many different bacterial species produce lipases which hydrolyze esters of glycerol with preferably long-chain fatty acids. They act at the interface generated by a hydrophobic lipid substrate in a hydrophilic aqueous medium. A characteristic property of lipases is called interfacial activation, meaning a sharp increase in lipase activity observed when the substrate starts to form an emulsion, thereby presenting to the enzyme an interfacial area. As a consequence, the kinetics of a lipase rea...
Khokhani, Devanshi; Zhang, Chengfang; Li, Yan; Wang, Qi; Zeng, Quan; Yamazaki, Akihiro; Hutchins, William; Zhou, Shan-Shan
Erwinia amylovora causes a devastating disease called fire blight in rosaceous plants. The type III secretion system (T3SS) is one of the important virulence factors utilized by E. amylovora in order to successfully infect its hosts. By using a green fluorescent protein (GFP) reporter construct combined with a high-throughput flow cytometry assay, a library of phenolic compounds and their derivatives was studied for their ability to alter the expression of the T3SS. Based on the effectiveness of the compounds on the expression of the T3SS pilus, the T3SS inhibitors 4-methoxy-cinnamic acid (TMCA) and benzoic acid (BA) and one T3SS inducer, trans-2-(4-hydroxyphenyl)-ethenylsulfonate (EHPES), were chosen for further study. Both the T3SS inhibitors (TMCA and BA) and the T3SS inducer (EHPES) were found to alter the expression of T3SS through the HrpS-HrpL pathway. Additionally, TMCA altered T3SS expression through the rsmBEa-RsmAEa system. Finally, we found that TMCA and BA weakened the hypersensitive response (HR) in tobacco by suppressing the T3SS of E. amylovora. In our study, we identified phenolic compounds that specifically targeted the T3SS. The T3SS inhibitor may offer an alternative approach to antimicrobial therapy by targeting virulence factors of bacterial pathogens. PMID:23770912
The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.
Sung Chul Yun
Full Text Available Bacteriolytic myxobacteria have been known to secrete various antifungal metabolites against several soilborne phytopathogens including Phytophthora. Among the three isolates of Myxococcus spp., KYC 1126 and KYC 1136 perfectly inhibited the mycelial growth of Phytophtora capsici in vitro. In order to show the biocontrol activity on Phytophthora blight of hot pepper, we tried to find the best way of application of myxobacterial isolate. Although KYC 1126 fruiting body was easily grown on the colony of Escherichia coli as a nutrient source, it did not control the disease when it was pre-applied in soil. Before the bioassay of a liquid culture filtrate of KYC 1126 was conducted, its antifungal activity was confirmed on the seedlings applying with the mixture of the pathogen`s zoospore suspension and KYC 1126 filtrate. On greenhouse experiments with five and four replications, the control value of KYC 1126 on phyllosphere and rhizosphere was 88% and 36%, respectively. Whereas, the control value of dimetnomorph+propineb on phyllosphere was 100% and that of propamorcarb on rhizosphere was 44%. There was a phytotoxicity of the myxobacterial filtrate when seedlings were washed and soaked for 24 hours. Gummy materials were covered with roots. And stem and petiole were constricted, then a whole seedling was eventually blighted.
Jason E. Woodward
Full Text Available Field studies were conducted from 2007 to 2010 to evaluate the response of peanut cultivars to different fungicides, application timings, and methods. Overall, fungicides reduced Sclerotinia blight incidence and increased pod yields when applied to susceptible and partially resistant cultivars. Disease suppression was greater when full fungicide rates were applied preventatively; however, yields between fungicide treated plots were similar. Lower levels of disease and higher yields were achieved with the partially resistant cultivar Tamrun OL07 compared to the susceptible cultivars Flavor Runner 458 and Tamrun OL 02. Despite possessing improved resistance Tamrun OL07 responded to all fungicide applications. While similar levels of disease control were achieved with broadcast or banded applications made during the day or at night, the yield response for the different application methods was inconsistent among years. A negative relationship (slope = −73.8; R2=0.73; P<0.01 was observed between final disease incidence ratings and yield data from studies where a fungicide response was observed. These studies suggest that both boscalid and fluazinam are effective at controlling Sclerotinia blight in peanuts. Alternative management strategies such as nighttime and banded applications could allow for lower fungicide rates to be used; however, additional studies are warranted.
Al-Safadi, B.; Arabi, M.I.E.
A mutation breeding program was conducted to improve potato resistance to late blight disease caused by Phytophthora infestans. In vitro cultured explants from cvs Draga, Diamant, Spunta were irradiated with gamma ray doses 25, 30, and 35 Gy. Growing shoots were cut and re-cultured every 2 weeks until the 4 th generation (MV 4 ) to make sure no chimeral tissues still existed in the mutant material. Plantlets were subsequently propagated to obtain enough explants for in vitro selection pressure. Around 3,000 plantlets from the 3 cultivars were subjected to selection pressure using co-culture technique. MV 4 explants were incubated in jars, containing MS medium, with mycelia of P. infestans. Surviving plantlets were propagated and re-incubated with the pathogen for 3 consecutive generations. Resistant plantlets were acclimatized and transferred to pots and grown under glasshouse conditions. Plants were later inoculated, at the adult stage, with sporangial suspension. Cv Draga produced the highest number of resistant plants. Ten plants of Draga appeared to be resistant to late blight, whereas only one plant from each of the other 2 cvs was resistant. Mutant plants varied in number of produced minitubers from 13 to 70. Also, weight of these minitubers varied from less than 1 to 35 grams. Selected mutant lines will undergo further testing under field conditions for P. infestans resistance and other agronomic characteristics
Al-Safadi, B.; Arabi, M.I.E.
A mutation breeding program was conducted to improve potato (Solanum tuberosum) resistance to late blight disease caused by Phytophthora infestans. In vitro cultured explants from potato cvs. Draga, Diamant, Spunta were irradiated with gamma ray doses 25, 30, and 35 Gy. Growing shoots were cut and re-cultured every 2 weeks until the 4 t h generation (MV 4 ) to make sure no chimeral tissues still existed in the mutant material. Plantlets were subsequently propagated to obtain enough explants for in vitro selection pressure. Around 3000 plantlets from the three cultivars were subjected to selection pressure using co-culture technique. MV 4 explants were incubated in jars, containing MS medium, with mycelia of P. infestans. Surviving plantlets were propagated and re-incubated with the pathogen for three consecutive generations. Resistant plantlets were acclimatized and transferred to pots and grown under glasshouse conditions. Plants were later inoculated, at the adult stage, with sporangial suspension. Cultivar Draga produced the highest number of resistant plants. Ten plants of Draga appeared to be resistant to late blight whereas only one plant from each of the other 2 cultivars was resistant. Mutant plants varied in number of produced minitubers from 13 to 70, Also, weight of these minitubers varied from less than 1 to 35 grams. Selected mutant lines will undergo further testing under field conditions for P. infestans resistance and other agronomic characteristics. (author)
Full Text Available Legume cultivation is strongly hampered by the occurrence of ascochyta blights. Strategies of control have been developed but only marginal successes have been achieved. Breeding for disease resistance is regarded the most cost efficient method of control. Significant genetic variation for disease resistance exists in most legume crops with numerous germplasm lines maintained, providing an excellent resource for plant breeders. Fast and reliable screening methods have been adjusted to fulfil breeding programmes needs. However, the complex inheritance controlled quantitatively by multiple genes, have been difficult to manipulate. Successful application of biotechnology to ascochyta blight resistance breeding in legume crops will facilitate both a good biological knowledge of the crops and of the mechanisms underlying resistance. The current focus in applied breeding is leveraging biotechnological tools to develop more and better markers to speed up the delivery of improved cultivars to the farmer. To date, however, progress in marker development and delivery of useful markers has been slow. The limited saturation of the genomic regions bearing putative QTLs in legume crops makes difficult to identify the most tightly-linked markers
Yang, Fen; Svensson, Birte; Finnie, Christine
Fusarium seedling blight in cereals can result in significant reductions in plant establishment but has not received much attention. The disease often starts during seed germination due to sowing of the seeds infected by Fusarium spp. including Fusarium graminearum. In order to gain the first molecular insights into the response of the germinating barley seeds to F. graminearum for controlling the disease, germinating seeds were treated with water as control or inoculated with F. graminearum conidia and samples were harvested at 1, 2 and 3 days after inoculation (dai). Although germination rates were not significantly different between F. graminearum-inoculated and control samples, albumins and hydrogen peroxide were accumulated in the inoculated samples at 1-3 dai, indicating that there was an interaction between the germinating seeds and F. graminearum. Subsequently, a gel-based proteomic approach was employed to identify differentially expressed proteins in the seeds responding to fungal infection at 3 dai, which revealed 42 protein spots, 41 of which were identified by mass spectrometry. The up-regulated proteins mainly included heat shock proteins, antioxidant enzymes and the proteins involved in primary metabolism and detoxification whereas the majority of down-regulated proteins were plant protease inhibitors. The results suggest that there is a link between increased energy metabolism and oxidative stress in the germinating barley seeds in response to F. graminearum infection, which provides the first molecular insight into Fusarium seedling blight. Copyright © 2011 Elsevier Masson SAS. All rights reserved.
A study was made to assess the impact of two late blight tolerant potato varieties Tigoni and Asante releases in 1998. The appraisal and impact assessment set out to collect information on the adoption of the two varieties; assess their economic impact; and forecast future prospects for these two varieties and identity constraints to their adoption and diffusion in three divisions of Molo, Timboroa and Laikipia. The methodology adopted was conducting field surveys between September and October 2001, and gathering secondary information from the Ministry of Agriculture, research Centres, seed companies, NGO's and farmers. Results indicated that high yield, early maturity, tolerant to late blight, good market for ware potatoes and good taste were the advantages of Tigoni and Asante, widely recognised in all survey sites. Disadvantages of Tigoni and Asante were poor storage, rapid greening of tubers (mainly for Tigoni), and limited availability of planting material. The two varieties had higher yield benefits, net benefit per hectare and higher rates of return compared to the local varieties. the rate of returns when the local cultivars were substituted by the new improved varieties ranged from 556 to 1070%. Data on diffusion of Tigoni and Asante showed that combined acreage of varieties Tigoni and Asante rose to 196.3, 137.5 and 1476 ha in Molo, Timboroa and Laikipia respectively. The future forecast for the two varieties is good if the limitation on seed availability is addressed
Gao, Liangliang; Bradeen, James M
The late blight pathogen Phytophthora infestans can attack both potato foliage and tubers. When inoculated with P. infestans, foliage of nontransformed 'Russet Burbank' (WT) develops late blight disease while that of transgenic 'Russet Burbank' line SP2211 (+RB) does not. We compared the foliar transcriptome responses of these two lines to P. infestans inoculation using an RNA-seq approach. A total of 515 million paired end RNA-seq reads were generated, representing the transcription of 29,970 genes. We also compared the differences and similarities of defense mechanisms against P. infestans in potato foliage and tubers. Differentially expressed genes, gene groups and ontology bins were identified to show similarities and differences in foliage and tuber defense mechanisms. Our results suggest that R gene dosage and shared biochemical pathways (such as ethylene and stress bins) contribute to RB-mediated incompatible potato-P. infestans interactions in both the foliage and tubers. Certain ontology bins such as cell wall and lipid metabolisms are potentially organ-specific.
Full Text Available Abstract Background The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L. and barley (Hordeum vulgare L. that reduces both grain yield and quality. Results A construct containing a bovine lactoferrin cDNA was used to transform wheat using an Agrobacterium-mediated DNA transfer system to express this antimicrobial protein in transgenic wheat. Transformants were analyzed by Northern and Western blots to determine lactoferrin gene expression levels and were inoculated with the head blight disease fungus F. graminearum. Transgenic wheat showed a significant reduction of disease incidence caused by F. graminearum compared to control wheat plants. The level of resistance in the highly susceptible wheat cultivar Bobwhite was significantly higher in transgenic plants compared to control Bobwhite and two untransformed commercial wheat cultivars, susceptible Wheaton and tolerant ND 2710. Quantification of the expressed lactoferrin protein by ELISA in transgenic wheat indicated a positive correlation between the lactoferrin gene expression levels and the levels of disease resistance. Conclusions Introgression of the lactoferrin gene into elite commercial wheat, barley and other susceptible cereals may enhance resistance to F. graminearum.
Sparks, Adam H; Forbes, Gregory A; Hijmans, Robert J; Garrett, Karen A
Weather affects the severity of many plant diseases, and climate change is likely to alter the patterns of crop disease severity. Evaluating possible future patterns can help focus crop breeding and disease management research. We examined the global effect of climate change on potato late blight, the disease that caused the Irish potato famine and still is a common potato disease around the world. We used a metamodel and considered three global climate models for the A2 greenhouse gas emission scenario for three 20-year time-slices: 2000-2019, 2040-2059 and 2080-2099. In addition to global analyses, five regions were evaluated where potato is an important crop: the Andean Highlands, Indo-Gangetic Plain and Himalayan Highlands, Southeast Asian Highlands, Ethiopian Highlands, and Lake Kivu Highlands in Sub-Saharan Africa. We found that the average global risk of potato late blight increases initially, when compared with historic climate data, and then declines as planting dates shift to cooler seasons. Risk in the agro-ecosystems analyzed, varied from a large increase in risk in the Lake Kivu Highlands in Rwanda to decreases in the Southeast Asian Highlands of Indonesia. © 2014 John Wiley & Sons Ltd.
Full Text Available The reaction of 21 tomato varieties and genotypes to alternaria blight were evaluated in greenhouse and field conditions. Genotypes and varieties were inoculated with of this pathogen artificially in both experiments. After inoculation, disease characteristics such as disease index, area under disease progress curve (AUDPC, percent of dried flower and yield in the field and disease index, percent of infected leaves and surfaces of blight on leaves in greenhouse were recorded. Results of greenhouse experiment showed that varieties and genotypes including Super 2270 King stone, Kallgi and 8403 had the least infection to disease. On the other hand, Imperial variety and 8406 genotype exhibited the highest amount of infection. Varieties in the field experiment, including Super 2270, King stone, Early urbano VF, and 8402 genotype, showed the least infection and genotypes like 8405, 8406, 8407 and Peto early ch variety had the highest amount of infection. In both experiments Super 2270, King stone and Early urbano VF varieties were found resistant to be this pathogen, but 8402 genotype was resistant only in the field and 8403 genotype and Kallgi variety were resistant only under greenhouse condition. Soria variety showed a considerable disease spot in both experiment but could produce the highest means of yield about 91.64 ton/ha. in the field, compared to other varieties and genotypes. Hence it is assumed to be the tolerant variety.
A. Dhole, S; Shaikh, Rukaiyya Pyarelal
- In agricultural field the plants comes to an attack from the various pets bacterial and micro-organism diseases. This diseases attacks on the plant leaves, steams, and fruit part. This present review paper discussed the image processing techniques which is used in performing the early detection of plant diseases through leaf feature inspection. the basic objective of this work is to develop image analysis and classification techniques for extraction and finally classified the diseases pre...
Møller-Jensen, Jakob; Borch, Jonas; Dam, Mette
Bacterial DNA segregation takes place in an active and ordered fashion. In the case of Escherichia coli plasmid R1, the partitioning system (par) separates paired plasmid copies and moves them to opposite cell poles. Here we address the mechanism by which the three components of the R1 par system...... movement is powered by insertional polymerization of ParM. Consistently, we find that segregating plasmids are positioned at the ends of extending ParM filaments. Thus, the process of R1 plasmid segregation in E. coli appears to be mechanistically analogous to the actin-based motility operating...
Charles C. Branas; Eugenia South; Michelle C. Kondo; Bernadette C. Hohl; Philippe Bourgois; Douglas J. Wiebe; John M. MacDonald
Vacant and blighted urban land is a widespread and potentially risky environmental condition encountered by millions of people on a daily basis. About 15% of the land in US cities is deemed vacant or abandoned, an area roughly the size of Switzerland. In a citywide cluster randomized controlled trial, we investigated the effects of standardized, reproducible...
Resistance in oats (Avena sativa L.) to infection by Fusarium graminearum was assessed in field trials in 2011-12 including 424 spring oat lines from North America and Scandinavia. Traits measured were Fusarium Head Blight (FHB), deoxynivalenol (DON) content, days to flowering (DTF) and days to matu...
Potato is the most important non-cereal crop in the world. Late blight, caused by the oomycete pathogen Phytophthora infestans, is the most devastating disease of potato. In the mid-191h century, P. infestans attacked the European potato fields and this resulted in a widespread famine in Ireland.
Kromann, Peter; Taipe, Arturo; Perez, Willmer G.
Accumulated rainfall thresholds were studied in seven field experiments conducted in Ecuador and Peru for their value in timing applications of fungicide to control potato late blight, caused by Phytophthora infestans. Fungicide regimes based on accumulated rainfall thresholds ranging from 10 to 70...
Iftikhar, Sehrish; Shahid, Ahmad A.; Halim, Sobia A.; Wolters, Pieter J.; Vleeshouwers, Vivianne G.A.A.; Khan, Ajmal; Al-Harrasi, Ahmed; Ahmad, Shahbaz
Alternaria blight is an important foliage disease caused by Alternaria solani. The enzyme Succinate dehydrogenase (SDH) is a potential drug target because of its role in tricarboxylic acid cycle. Hence targeting Alternaria solani SDH enzyme could be efficient tool to design novel fungicides against
Mideros, M.F.; Turissini, D.A.; Guayazán, N.; Ibarra-Avila, H.; Danies, G.; Cárdenas, M.; Myers, K.; Tabima, J.; Goss, E.M.; Bernal, A.; Lagos, L.E.; Grajales, A.; Gonzalez, L.N.; Cooke, D.E.L.; Fry, W.E.; Grünwald, N.; Matute, D.R.; Restrepo, S.
Over the past few years, symptoms akin to late blight disease have been reported on a variety of crop plants in South America. Despite the economic importance of these crops, the causal agents of the diseases belonging to the genus Phytophthora have not been completely characterized. In this study,
Palisade Russet is a medium-late maturing, lightly russeted potato breeding clone notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber. Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage ...
This article describes updates found in Version 7.1 of the fire blight prediction model Maryblyt, originally developed by Paul Steiner and Gary Lightner. In addition, a brief history of the development of the Maryblyt model is given. The article ends with examples comparing the performance of Versio...
Climate change and wheat corn rotation agriculture have spawned massive epidemics of Fusarium head blight (FHB) on cereal crops mainly wheat and barley since the 1990’s and devastated farm economies of north central US and many of the major wheat growing regions of the world. Wheat has limited resis...
Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...
Pantoea agglomerans strain E325 is available commercially as the active ingredient in a freeze-dried product (Bloomtime FDTM) of Northwest Agricultural Products (NAP) for biological control of fire blight. Osmoadaptation, which involves the combination of Pantoea agglomerans strain E325 is available...
Chandra, Swarnendu; Chakraborty, Nilanjan; Panda, Koustubh; Acharya, Krishnendu
Blister blight disease, caused by an obligate biotrophic fungal pathogen, Exobasidium vexans Massee is posing a serious threat for tea cultivation in Asia. As the use of chemical pesticides on tea leaves substantially increases the toxic risks of tea consumption, serious attempts are being made to control such pathogens by boosting the intrinsic natural defense responses against invading pathogens in tea plants. In this study, the nature and durability of resistance offered by chitosan and the possible mechanism of chitosan-induced defense induction in Camellia sinensis (L.) O. Kuntze plants against blister blight disease were investigated. Foliar application of 0.01% chitosan solution at 15 days interval not only reduced the blister blight incidence for two seasons, but also maintained the induced expressions of different defense related enzymes and total phenol content compared to the control. Defense responses induced by chitosan were found to be down regulated under nitric oxide (NO) deficient conditions in vivo, indicating that the observed chitosan-induced resistance is probably activated via NO signaling. Such role of NO in host defense response was further established by application of the NO donor, sodium nitroprusside (SNP), which produced similar defense responses accomplished through chitosan treatment. Taken together, our results suggest that increased production of NO in chitosan-treated tea plants may play a critical role in triggering the innate defense responses effective against plant pathogens, including that causing the blister blight disease. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Skelsey, P.; Kessel, G.J.T.; Holtslag, A.A.M.; Moene, A.F.; Werf, van der W.
This study develops and tests a novel approach for including regional risk factors in operational disease risk warnings against potato late blight. The central premise is that fungicide inputs can be reduced by omitting applications on days when conditions are unsuitable for the atmospheric
Skelsey, P.; Kessel, G. J. T.; Holtslag, A. A. M.; Moene, A. F.; van der Werf, W.
This study develops and tests a novel approach for including regional risk factors in operational disease risk warnings against potato late blight. The central premise is that fungicide inputs can be reduced by omitting applications on days when conditions are unsuitable for the atmospheric
Fusarium head blight (FHB) resistance was identified in the alien species Leymus racemosus, and wheat-Leymus introgression lines with FHB resistance were reported previously. Detailed molecular cytogenetic analysis of alien introgressions T01, T09, and T14 and the mapping of Fhb3, a new gene for FHB...
Fungicides are most warranted for control of Fusarium head blight (FHB), a disease of wheat caused by the fungal pathogen Fusarium graminearum, when wet, rainy conditions occurs during anthesis. However, it is unclear whether rainfall directly following application affects fungicide efficacy against...
Full Text Available We consider two ways of inserting a key into a binary search tree: leaf insertion which is the standard method, and root insertion which involves additional rotations. Although the respective cost of constructing leaf and root insertion binary search trees trees, in terms of comparisons, are the same in the average case, we show that in the worst case the construction of a root insertion binary search tree needs approximately 50% of the number of comparisons required by leaf insertion.
Mihovilovich, E; Munive, S; Bonierbale, M
Main and interaction effects of day-length and pathogen isolate on the reaction and expression of field resistance to Phytophthora infestans were analyzed in a sample of standard clones for partial resistance to potato late blight, and in the BCT mapping population derived from a backcross of Solanum berthaultii to Solanum tuberosum. Detached leaves from plants grown in field plots exposed to short- and long day-length conditions were independently inoculated with two P. infestans isolates and incubated in chambers under short- and long photoperiods, respectively. Lesion growth rate (LGR) was used for resistance assessment. Analysis of variance revealed a significant contribution of genotype x isolate x day-length interaction to variation in LGR indicating that field resistance of genotypes to foliar late blight under a given day-length depended on the infecting isolate. An allele segregating from S. berthaultii with opposite effects on foliar resistance to late blight under long- and short day-lengths, respectively, was identified at a quantitative trait locus (QTL) that mapped on chromosome 1. This allele was associated with positive (decreased resistance) and negative (increased resistance) additive effects on LGR, under short- and long day-length conditions, respectively. Disease progress on whole plants inoculated with the same isolate under field conditions validated the direction of its effect in short day-length regimes. The present study suggests the occurrence of an isolate-specific QTL that displays interaction with isolate behavior under contrasting environments, such as those with different day-lengths. This study highlights the importance of exposing genotypes to a highly variable population of the pathogen under contrasting environments when stability to late blight resistance is to be assessed or marker-assisted selection is attempted for the manipulation of quantitative resistance to late blight.
Gerrit TS Beemster
Full Text Available Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana.
Peter B. Reich; Michael B. Walters; David S. Ellsworth; [and others; [Editor’s note: James M.. Vose is the SRS co-author for this publication.
Based on prior evidence of coordinated multiple leaf trait scaling, the authors hypothesized that variation among species in leaf dark respiration rate (Rd) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (Amax). However, it is not known whether such scaling, if it exists, is...
Estimation of leaf area (LA) and leaf biomass (LB) is important to understand plant physiological and carbon assimilation processes, and tree growth models. The aim of this study was to develop and compare allometric equations for predicting LA and LB of Artocarpus chaplasha Roxb. taking diameter at breast height ...
Full Text Available In this study, the adsorption potential of Teak (Tectona grandis leaf powder (TLP toremove Methylene blue (MB and Malachite Green (MG dye molecules from aqueoussolution was investigated. Batch experiments were conducted to evaluate the influenceof operational parameters such as, pH (2−9, adsorbent dosage (1−7 g/L, contact time(15−150 minutes and initial dye concentration (20−120 mg/L at stirring speed of 150rpm for the adsorption of MB and MG on TLP. Maximum removal efficiency of 98.4%and 95.1% was achieved for MB and MG dye, respectively. The experimentalequilibrium data were analysed using Langmuir, Freundlich and Temkin isothermmodels and it was found that, it fitted well to the Freundlich isotherm model. Thesurface structure and morphology of the adsorbent was characterized using scanningelectron microscopy (SEM and the presence of functional groups and its interactionwith the dye molecules were analysed using Fourier transform infrared spectroscopy(FTIR. Based on the investigation, it has been demonstrated that the teak leaf powderhas good potential for effective adsorption of methylene blue and malachite green dye.
Nocera, Daniel G
To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a
Wright, I.J.; Reich, P.B.; Westoby, M.; Ackerly, D.D.; Baruch, Z.; Bongers, F.J.J.M.; Cavender-Bares, J.; Chapin, T.; Cornelissen, J.H.C.; Diemer, M.; Flexas, J.; Garnier, E.; Groom, P.K.; Gulias, J.; Hikosaka, K.; Lamont, B.B.; Lee, T.; Lee, W.; Lusk, C.; Midgley, J.J.; Navas, M.L.; Niinements, Ü.; Oleksyn, J.; Osada, N.; Poorter, H.; Poot, P.; Prior, L.; Pyankov, V.I.; Roumet, C.; Thomas, S.C.; Tjoelker, M.G.; Veneklaas, E.J.; Villar, R.
Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients
Tan, Diana C; Flematti, Gavin R; Ghisalberti, Emilio L; Sivasithamparam, Krishnapillai; Chakraborty, Sukumar; Obanor, Friday; Jayasena, Kithsiri; Barbetti, Martin J
An isolated occurrence of Fusarium head blight (FHB) of wheat was detected in the south-west region of Western Australia during the 2003 harvest season. The molecular identity of 23 isolates of Fusarium spp. collected from this region during the FHB outbreak confirmed the associated pathogens to be F. graminearum, F. acuminatum or F. tricinctum. Moreover, the toxicity of their crude extracts from Czapek-Dox liquid broth and millet seed cultures to brine shrimp (Artemia franciscana) was associated with high mortality levels. The main mycotoxins detected were type B trichothecenes (deoxynivalenol and 3-acetyldeoxynivalenol), enniatins, chlamydosporol and zearalenone. This study is the first report on the mycotoxin profiles of Fusarium spp. associated with FHB of wheat in Western Australia. This study highlights the need for monitoring not just for the presence of the specific Fusarium spp. present in any affected grain but also for their potential mycotoxin and other toxic secondary metabolites.
Leila Garcês de Araújo
Full Text Available Field and greenhouse inoculation methods were compared to determine the genetic variation for resistance toRhizoctonia solani in 38 somaclones of rice cultivar Metica-1. Rice plants in pots were inoculated with isolate 4F1 at the ageof sixty four days, with 2.0 g of the fungal culture, multiplied on rice grain and hull medium and placed on the soil surfacearound the plant. The differences among somaclones in relation to lesion height were significant and varied from 6.5 to 15.5cm. In the field trial of artificial inoculation with fungal culture, 52 days after planting, the lesion height varied from 6.2 to 17.7cm. The correlation between disease severity in the greenhouse and the field was positive and highly significant (r=0.44;P< 0.01, indicating the greenhouse inoculation as a safe method for screening germplasm for sheath blight resistance.
Novisel Veitía Rodríguez
Full Text Available The behavior of variantees IBP-10, IBP-27, the varieties ‘Diacol capiro’, ‘Desirée’ and Solanum chacoense species was evaluated in seedbed in front of Early blight diseases. Artificial inoculation with micelial homogenized of CCIBP-As4 isolated obtained at the Phytopathology laboratory from the Instituto de Biotecnología de las Plantas. The number and weight of tubers was also evaluated in the studied genotypes. It was observed differential behavior in the intensity of the affectations caused by the disease in the evaluated genotypes. An increase in the intensity of the affectations from 50 days the plants had sprouted was observed. It was realized that the ‘Diacol capiro’ variety presented greater number of tubers but their weight was lower. The IBP-10 reached superior values in both variables with respect to the variety ‘Desirée’. Key words: early selection, intensity of attack, variants
Full Text Available Standard program of plant protection against fire blight consists of use of management practices and chemical control method. Recently a new, non-conventional possibilities based on application of biocontrol agents (two biopreparations have been already introduced into practice: Bliteban A506 (Pseudomonas fluorescens and BlossomBless (Pantoea agglomerans, plant extracts active against Erwinia amylovora (AkseBio containing extracts from Thymbra spicata and Biomit Plussz with extracts from various plant species and microelements and resistance inducers (Regalis, Bion and plant extracts are of great interest. Also plant transformation with resistance genes such as: hrpN (harpin, dpo (EPS depolymerase and lytic protein genes (attacin E, cecropin SB-37, T4 lysozyme is a promising perspective.
Full Text Available Fusarium head blight is a destructive disease of cereals worldwide. The aim of this research was to study the effect of heavy Fusarium infection with Fusarium culmorum and biosynthesis of mycotoxins on different wheat varieties during malting by setting up field trials with control and Fusarium-inoculated treatments at the Agricultural Institute Osijek. The highest occurrence of Fusarium mycotoxins was expectedly recorded in susceptible variety in grain and malt (3247 and 1484 µg kg−1 for deoxynivalenol (DON, 735 and 1116 µg kg−1 for 3-acetyl deoxynivalenol (3-ADON, 37 and 233 µg kg−1 for zearalenone (ZEN, respectively. Based on published information, complemented by our own results, the following conclusions can be drawn: The presence of 3-ADON in different wheat varieties might be the result of its conversion into DON by deacetylation during the malting process. The detection of the mycotoxin ZEN indicated that this mycotoxin is only specific for wheat malt.
Newman, Molli M; Liles, Mark R; Feminella, Jack W
Microbial succession during leaf breakdown was investigated in a small forested stream in west-central Georgia, USA, using multiple culture-independent techniques. Red maple (Acer rubrum) and water oak (Quercus nigra) leaf litter were incubated in situ for 128 days, and litter breakdown was quantified by ash-free dry mass (AFDM) method and microbial assemblage composition using phospholipid fatty acid analysis (PLFA), ribosomal intergenic spacer analysis (RISA), denaturing gradient gel electrophoresis (DGGE), and bar-coded next-generation sequencing of 16S rRNA gene amplicons. Leaf breakdown was faster for red maple than water oak. PLFA revealed a significant time effect on microbial lipid profiles for both leaf species. Microbial assemblages on maple contained a higher relative abundance of bacterial lipids than oak, and oak microbial assemblages contained higher relative abundance of fungal lipids than maple. RISA showed that incubation time was more important in structuring bacterial assemblages than leaf physicochemistry. DGGE profiles revealed high variability in bacterial assemblages over time, and sequencing of DGGE-resolved amplicons indicated several taxa present on degrading litter. Next-generation sequencing revealed temporal shifts in dominant taxa within the phylum Proteobacteria, whereas γ-Proteobacteria dominated pre-immersion and α- and β-Proteobacteria dominated after 1 month of instream incubation; the latter groups contain taxa that are predicted to be capable of using organic material to fuel further breakdown. Our results suggest that incubation time is more important than leaf species physicochemistry in influencing leaf litter microbial assemblage composition, and indicate the need for investigation into seasonal and temporal dynamics of leaf litter microbial assemblage succession.
Full Text Available Plasmids, extrachromosomal DNA, were identified in bacteria pertaining to family of Enterobacteriacae for the very first time. After that, they were discovered in almost every single observed strain. The structure of plasmids is made of circular double chain DNA molecules which are replicated autonomously in a host cell. Their length may vary from few up to several hundred kilobase (kb. Among the bacteria, plasmids are mostly transferred horizontally by conjugation process. Plasmid replication process can be divided into three stages: initiation, elongation, and termination. The process involves DNA helicase I, DNA gyrase, DNA polymerase III, endonuclease, and ligase.Plasmids contain genes essential for plasmid function and their preservation in a host cell (the beginning and the control of replication. Some of them possess genes whichcontrol plasmid stability. There is a common opinion that plasmids are unnecessary fora growth of bacterial population and their vital functions; thus, in many cases they can be taken up or kicked out with no lethal effects to a plasmid host cell. However,there are numerous biological functions of bacteria related to plasmids. Plasmids identification and classification are based upon their genetic features which are presented permanently in all of them, and these are: abilities to preserve themselves in a host cell and to control a replication process. In this way, plasmids classification among incompatibility groups is performed. The method of replicon typing, which is based on genotype and not on phenotype characteristics, has the same results as in compatibility grouping.
Rahman, M M; Ahmad, S H; Mohamed, M T M; Ab Rahman, M Z
The present research was conducted to discover antimicrobial compounds in methanolic leaf extracts of Jatropha curcas and Andrographis paniculata and ethanolic leaf extract of Psidium guajava and the effectiveness against microbes on flower preservative solution of cut Mokara Red orchid flowers was evaluated. The leaves were analyzed using gas chromatography-mass spectrometry. A total of nine, 66, and 29 compounds were identified in J. curcas, P. guajava, and A. paniculata leaf extracts, with five (88.18%), four (34.66%), and three (50.47%) having unique antimicrobial compounds, respectively. The experimental design on vase life was conducted using a completely randomized design with 10 replications. The flower vase life was about 6 days in the solution containing the P. guajava and A. paniculata leaf extracts at 15 mg/L. Moreover, solution with leaf extracts of A. paniculata had the lowest bacterial count compared to P. guajava and J. curcas. Thus, these leaf extracts revealed the presence of relevant antimicrobial compounds. The leaf extracts have the potential as a cut flower solution to minimize microbial populations and extend flower vase life. However, the activities of specific antimicrobial compounds and double or triple combination leaf extracts to enhance the effectiveness to extend the vase life need to be tested.
Lou, Z; Wang, H; Tang, Y; Chen, X
This study aimed to evaluate the effect of a fraction of burdock (Arctium lappa L.) leaf on the initial adhesion, biofilm formation, quorum sensing and virulence factors of Pseudomonas aeruginosa. Antibiofilm activity of the burdock leaf fraction was studied by the method of crystal violet staining. When the concentration of the burdock leaf fraction was 2·0 mg ml -1 , the inhibition rates on biofilm formation of P. aeruginosa were 100%. The burdock leaf fraction was found to inhibit the formation of biofilm by reducing bacterial surface hydrophobicity, decreasing bacterial aggregation ability and inhibiting swarming motility. Interestingly, the burdock leaf fraction inhibited the secretion of quorum-sensing (QS) signalling molecule 3-oxo-C12-HSL and interfered quorum sensing. Moreover, the QS-regulated pyocyanin and elastase were also inhibited. Chemical composition analysis by UPLC-MS showed 11 active compounds in the burdock leaf fraction. The burdock leaf fraction significantly inhibited the formation of biofilm and quorum sensing, as well as significantly decreased the content of virulence factors. This study introduces a natural and effective bacterial biofilm inhibitor, which could also significantly decrease the content of virulence factors and the drug resistance of P. aeruginosa. © 2016 The Society for Applied Microbiology.
Severidade da mela da soja causada por Rhizoctonia solani AG-1 IA em função de doses de potássio Severity of hte foliar blight of the soylean caused by Rhizoctonia solani AG-1 IA infunction of doses of potassium
Marco Antonio Basseto
Full Text Available O fungo Rhizoctonia solani pertencente ao grupo de anastomose 1 IA (AG-1 IA é um dos patógenos mais importantes afetando a cultura da soja no Brasil. Este fungo causa queima da folha e/ou mela em soja, para a qual medidas de manejo cultural são consideradas alternativas importantes para controle antes do estabelecimento da doença. Há evidências de que a adubação potássica diminui substancialmente a severidade dos sintomas de várias doenças da soja como a queima foliar (Cercospora kikuchii, a seca da haste e da vagem (Phomopsis phaseoli var. sojae e o cancro da haste (Diaporthe phaseolorum f. sp. meridionalis. Apesar das evidências do efeito do potássio no controle de várias doenças da soja, não há informação na literatura sobre o efeito desse nutriente no controle da mela. A hipótese testada foi que a mela da soja pode ser controlada através de incrementos na adubação potássica. De maneira geral, concluiu-se que, sob condições de casa de vegetação, o incremento de K no solo não resultou no controle da mela da soja. É necessário, entretanto, confirmar esta observação conduzindo-se experimentos sob condições de campo, podendo-se incluir a avaliação do efeito da doença sob aspectos da produção.The fungus Rhizoctonia solani, belonging to anastomosis group 1IA (AG-1 IA is one of the most important pathogens affecting soybean in Brazil. This fungus causes aerial or foliar blight of soybean, and cultural measures are thought as important choices for the control before the establishment of the disease. Based on evidences that potassium amendments can substantially reduce the severity of several soybean diseases such as Cercospora leaf blight (Cercospora kikuchii, pod and stem blight (Phomopsis phaseoli var. sojae and stem canker (Diaporthe phaseolorum f. sp. meridionalis. Despite all evidence, there is no information in the literature about the effect of potassium controlling the soybean foliar blight. The
Gusberti, Michele; Klemm, Urs; Meier, Matthias S; Maurhofer, Monika; Hunger-Glaser, Isabel
Fire blight (FB), caused by Erwinia amylovora, is one of the most important pome fruit pathogens worldwide. To control this devastating disease, various chemical and biological treatments are commonly applied in Switzerland, but they fail to keep the infection at an acceptable level in years of heavy disease pressure. The Swiss authorities therefore currently allow the controlled use of the antibiotic streptomycin against FB in years that are predicted to have heavy infection periods, but only one treatment per season is permitted. Another strategy for controlling Erwinia is to breed resistant/tolerant apple cultivars. One way of accelerating the breeding process is to obtain resistant cultivars by inserting one or several major resistance genes, using genetic engineering. To date, no study summarizing the impact of different FB control measures on the environment and on human health has been performed. This study consequently aims to compare different disease-control measures (biological control, chemical control, control by antibiotics and by resistant/tolerant apple cultivars obtained through conventional or molecular breeding) applied against E. amylovora, considering different protection goals (protection of human health, environment, agricultural diversity and economic interest), with special emphasis on biosafety aspects. Information on each FB control measure in relation to the specified protection goal was assessed by literature searches and by interviews with experts. Based on our results it can be concluded that the FB control measures currently applied in Switzerland are safe for consumers, workers and the environment. However, there are several gaps in our knowledge of the human health and environmental impacts analyzed: data are missing (1) on long term studies on the efficacy of most of the analyzed FB control measures; (2) on the safety of operators handling streptomycin; (3) on residue analyses of Equisetum plant extract, the copper and aluminum
Narayan Bahadur Dhami
Full Text Available Biotic and biotic constraints are yield limiting factors in maize producing regions. Among these gray leaf spot is a yield limiting foliar disease of maize in high land regions of Asia. This review is done from related different national and international journals, thesis, books, research papers etc. The objectives of this review are to become familiar with genetics and inheritance, epidemiology, symptoms and disease management strategies etc. High relative humidity, temperature, minimum tillage and maize monoculture are important factors responsible for disease development. The sibling species of Cercospora zeae-maydis (Tehon and Daniels, 1925 Group I and Group II and Cercospora sorghai var. maydis (Chupp, 1954 are associated with this disease. Pathogens colonize in maize debris. Conidia are the source of inoculums for disease spread. Severe blighting of leaves reduces sugars, stalk lodging and causes premature death of plants resulting in yield losses of up to 100%. Disease management through cultural practices is provisional. The use of fungicides for emergencies is effective however; their prohibitive cost and detrimental effects on the environment are negative consequences. The inheritance of tolerance is quantitative with small additive effects. The introgression of resistant genes among the crosses of resistant germplasm enhances the resistance. The crosses of resistant and susceptible germplasm possess greater stability than the crosses of susceptible and resistant germplasm. The development of gray leaf spot tolerant populations through tolerance breeding principle is an economical and sustainable approach to manage the disease.
Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D
Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements. © 2013 Published by Elsevier Ltd. All rights reserved.
Leaf architectural traits, such as length, width and angle, directly influence canopy structure and light penetration, photosynthate production and overall yield. We discovered and characterized a maize (Zea mays) mutant with aberrant leaf architecture we named drooping leaf1 (drl1), as leaf blades ...
Early detection of disease and insect infestation within crops and precise application of pesticides can help reduce potential production losses, reduce environmental risk, and reduce the cost of farming. The goal of this study was the advanced detection of early blight (Alternaria solani) in potato (Solanum tuberosum) plants using hyperspectral remote sensing data captured with a handheld spectroradiometer. Hyperspectral reflectance spectra were captured 10 times over five weeks from plants grown to the vegetative and tuber bulking growth stages. The spectra were analyzed using principal component analysis (PCA), spectral change (ratio) analysis, partial least squares (PLS), cluster analysis, and vegetative indices. PCA successfully distinguished more heavily diseased plants from healthy and minimally diseased plants using two principal components. Spectral change (ratio) analysis provided wavelengths (490-510, 640, 665-670, 690, 740-750, and 935 nm) most sensitive to early blight infection followed by ANOVA results indicating a highly significant difference (p potato plants.
Hu, Jiahuai; Telenko, Darcy E P; Phipps, Patrick M; Grabau, Elizabeth A
This study presents the results of a comparison that includes an analysis of variance and a canonical discriminant analysis to determine compositional equivalence and similarity between transgenic, sclerotinia blight-resistant and non-transgenic, susceptible cultivars of peanut in 3 years of field trials. Three Virginia-type cultivars (NC 7, Wilson, and Perry) and their corresponding transgenic lines (N70, W73, and P39) with a barley oxalate oxidase gene were analyzed for differences in key mineral nutrients, fatty acid components, hay constituents, and grade characteristics. Results from both analyses demonstrated that transgenic lines were compositionally similar to their non-transgenic parent cultivar in all factors as well as market-grade characteristics and nutritional value. Transgenic lines expressing oxalate oxidase for resistance to sclerotinia blight were substantially equivalent to their non-transgenic parent cultivar in quality and compositional characteristics.
Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert
Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.
E VENUGOPAL GOUD; G HARINATH GOWD
Leaf springs are special kind of springs used in automobile suspension systems. The advantage of leaf spring over helical spring is that the ends of the spring may be guided along a definite path as it deflects to act as a structural member in addition to energy absorbing device. The main function of leaf spring is not only tosupport vertical load but also to isolate road induced vibrations. It is subjected to millions of load cycles leading to fatigue failure. Static analysis determines the ...
Hussain, A.; Qurshi, I.A.; Liaqat, R.; Akhtar, S.; Aziz, I.
Olive tree is the first botanical noted in the Bible. Leaves and fruits of olive are rich sources of Phenols, triterpenes, and flavanoids. Oleuropein obtained from the leaves extract is believed to be important therapeutic compound. Olive leaf and oils are used for the treatment of different diseases as folklore medicines by different ethnic groups in different countries of the world. The present study aims to investigate the potential antimicrobial activities of wild (Olea ferruginea) and edible (Olea europaea) olive leaf crude extracts, crude oils from ripe and unripe fruits and extra virgin oils against the selected gram positive and gram negative bacterial strains. The results show that olive leaf and oil have potential antibacterial activities against some of the gram positive and gram negative bacterial strains. However, certain strains were resistant to the extracts. It was also found that the activities were higher for the gram negative strains as compared to gram positive strains. The methanolic and ethanolic extracts were found to be more efficient in extraction than the other solvents used. Leaf extracts were more effective than the oil extracted from ripe and unripe fruits. There was no significant difference in the activities of extra virgin oils and crude leaf extracts. From the results it is concluded that the leaf extract is a cheap and effective antibacterial agent that can be used as alternative to purified oil. (author)
Pieterse, C.M.J.; Riach, M.B.R.; Bleker, T.; Berg-Velthuis, G.C.M. van den; Govers, F.
Plant pathogens produce pathogenicity factors which enable them to parasitize and colonize their host. A strategy for identifying pathogenicity factors involves the isolation and characterization of genes encoding these factors. Potential pathogenicity genes are genes whose expression is induced during pathogenesis. In order to isolate such genes of the late blight Fungus Phytophthora infestans , a genomic library of P. infestans DNA was differentially hybridized using labelled first strand c...
Full Text Available Sheath blight caused by Rhizoctonia solani is one of the most serious rice diseases worldwide. The disease is currently managed only by the excessive application of chemical fungicides which are toxic and not environmentally friendly. Therefore, greater emphasis should be given to biological control as being both safe and effective. Trichoderma species are ubiquitous fungi in the soil and have an antagonistic activity against several soil-borne plant pathogens including R. solani. The present study was undertaken to evaluate the potential of indigenous Trichoderma strains from Mazandaran province, Northern Iran (a Mediterranean region on the southern coast of the Caspian Sea against R. solani AG1-IA in vitro, and against sheath blight disease in the glasshouse, in order to find biocontrol isolates for application in the field. More than 200 Trichoderma strains were isolated from the soil, plant debris and the phyllosphere in rice felds. Strains were first screened for their antagonism to R. solani by in vitro antagonism tests including dual culture, antibiosis, the effect of Trichoderma strains on the production and viability of R. solani sclerotia, and hyperparasitism on microscopic slides. According to the in vitro experiments, several strains belonging to T. harzianum, T. virens and T. atroviride showed excellent biocontrol. These potential antagonist strains were further evaluated for their effectiveness in controlling sheath blight under glasshouse conditions. Among the 55 selected strains, seven significantly controlled the disease. T. harzianum AS12-2 was the most effective strain in controlling rice sheath blight, better even than propiconazole, the most commonly used fungicide in Iran.
Full Text Available Background: Blighted ovum is one of the most common reasons for abortion during the first three months of pregnancy. Manganese superoxide dismutase (MnSOD is an important antioxidant enzyme in the human immune system. The gene is located on 6q25 chromosome and acts on mitochondrial matrix. In the case of mutation or inactivity of this enzyme, mitochondrial and nuclear DNA will severely be destructed. The most common polymorphism of its gene is Val16Ala. Objective: The aim was to investigate a possible mutation in pregnant women who had abortion during the first trimester of pregnancy due to blighted ovum. Materials and Methods: In this case-control study, 34 women were entered as the case and control groups, respectively. Genome DNA was extracted from saliva samples and its genotype was determined using Tetra-primer amplification refractory mutation system polymerase chain reaction technique. Results: In the case group, 16 (48% cases had Val/Val genotype, 17 (50% were heterozygote and had Val/Ala genotype, and 1 (2% had Ala/Ala genotype. Among controls, 7 (22% items had Val/Val genotype, 6 (17% had Val/Ala genotype, and 21 (61% had Ala/Ala genotype. The frequency of TT, CT, and CC genotypes was 48%, 50%, and 2% in case group and 22%, 17%, and 61% in control group, respectively. Statistical analysis revealed a significant relationship between Val16Ala polymorphism of MnSOD gene and blighted ovum (p= 0.0003. Conclusion: It has concluded that a significant relationship exists between Val16Ala polymorphism of MnSOD gene and blighted ovum.
van der Graaff, Eric; Hooykaas, P J
We report here an efficient Arabidopsis leafdisc transformation protocol yielding an average transformation frequency of 1.6 transgenic shoots per leaf explant 4 weeks after the bacterial infection period. Subsequent cultivation in vitro is such that a high percentage (85-90%) of the primary tran...
Brouwer, Paul; Bräutigam, Andrea; Buijs, Valerie A.; Tazelaar, Anne O.E.; Werf, van der Adrie; Schlüter, Urte; Reichart, Gert Jan; Bolger, Anthony; Usadel, Björn; Weber, Andreas P.M.; Schluepmann, Henriette
Sustainable agriculture demands reduced input of man-made nitrogen (N) fertilizer, yet N2 fixation limits the productivity of crops with heterotrophic diazotrophic bacterial symbionts. We investigated floating ferns from the genus Azolla that host phototrophic diazotrophic Nostoc azollae in leaf
Afrah Eltayeb Mohammed
Conclusions: Our findings indicated that extracellular synthesis of AgNPs mediated by E. camaldulensis leaf extract had an efficient bactericidal activity against the bacterial species tested. The exact mechanism of the extracellular biosynthesis of metal NP was not well understood. Further studies are needed to highlight the biosynthesis process of AgNPs and also to characterize the toxicity effect of these particles.
Gil R. dos Santos
32 m were established in areas free of the disease, without any history of cucurbit cultivation, and no control measures were applied. Data for the disease progress curves were obtained from the mean diseased leaf area in an area of 768 m², at 45; 50; 55; 60; 65; 74; 80 and 87 days after planting (DAP. Disease progressed according to the exponential model, even under marginally favorable environmental conditions. Maximum severity values were observed 87 DAP (12.5-13.6% diseased leaf area. The crop loss experiment was laid out in a randomized completed block design with five disease levels and four replicates. Disease levels were obtained with the application of five fungicide doses (per 100 L of water of a mixture of active ingredients chlorothalonil and methyl thiophanate, as follows: (a 0 g a.i. (control; (b chlorothalonil 25 g + methyl thiophanate 10 g; (c chlorothalonil 75 g + methyl thiophanate 30 g; (d chlorothalonil 125 g + methyl thiophanate 50 g; (e chlorothalonil 250 g + methyl thiophanate 100 g. Disease severity was evaluated once, 78 DAP, with a disease scale ranging from 0 to 9, based on the percentage of diseased leaf area. Maximum disease levels were observed 78 DAP in control plots (26.5% diseased leaf area. There was high negative correlation (r=-0.96 between disease levels and fruit yield. Yield losses due to gummy stem blight reached 19.2% and chemical control reduced disease levels significantly.
Full Text Available Fusarium head blight (FHB incidence, and colonisation of grain by Fusarium species on winter wheat grown in organic, integrated, and conventional systems as well as in monoculture, were studied locally in Poland, from 2002 to 2010. Fusarium head blight incidence differed throughout the study years. It was found to occur the most where rainfall was highest and where rainfall was the most prolonged before, during, and after flowering of wheat. Fusarium head blight incidence was generally less on wheat grown organically than on wheat grown in other systems. In some years, FHB was noted more in monocultures than in other systems. Fusarium poae was the most common species of FHB populations in wheat kernels, followed by F. avenaceum and F. tricinctum. Other species which occurred more rarely or sporadically were: F. culmorum, F. equiseti, F. graminearum, F. langsethiae, F. oxysporum, and F. sporotrichioides. There were found to be significant effects of the cropping system on grain colonisation by Fusarium in some years. There was a positive correlation between FHB incidence and number of kernels colonised and damaged by Fusarium, in all four systems. Inferences were drawn concerning the effects of different procedures in different production systems and the possible value for controlling FHB
Hodgson, J.G.; Montserrat-Marti, G.; Charles, M.; Jones, G.; Wilson, P.; Shipley, B.; Sharafi, M.; Cerabolini, B.E.L.; Cornelissen, J.H.C.; Band, S.R.; Bogard, A.; Castro-Diez, P.; Guerrere-Campo, J.; Palmer, C.; Peréz-Rontomé, M.C.; Carter, G.; Hynd, A.; Romo-Diez, A.; De Torres Espuny, L.; Royo Pla, F.
Background and Aims: Specific leaf area (SLA), a key element of the 'worldwide leaf economics spectrum', is the preferred 'soft' plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and
Full Text Available The growing environmental problems, the problem of waste disposal and the depletion of non-renewable resources have stimulated the use of green materials compatible with the environment to reduce environmental impacts. Therefore, there is a need to design products by using natural resources. Natural fibers seem to be a good alternative since they are abundantly available and there are a number of possibilities to use all the components of a fiber-yielding crop; one such fiber-yielding plant is Agave Americana. The leaves of this plant yield fibers and all the parts of this plant can be utilized in many applications. The “zero-waste” utilization of the plant would enable its production and processing to be translated into a viable and sustainable industry. Agave Americana fibers are characterized by low density, high tenacity and high moisture absorbency in comparison with other leaf fibers. These fibers are long and biodegradable. Therefore, we can look this fiber as a sustainable resource for manufacturing and technical applications. Detailed discussion is carried out on extraction, characterization and applications of Agave Americana fiber in this paper.
Full Text Available Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats, but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently
Aćimović, Srđan G; Zeng, Quan; McGhee, Gayle C; Sundin, George W; Wise, John C
Management of fire blight is complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. Even though successful in control, preventive antibiotic sprays also affect non-target bacteria, aiding the selection for resistance which could ultimately be transferred to the pathogen Erwinia amylovora. Trunk injection is a target-precise pesticide delivery method that utilizes tree xylem to distribute injected compounds. Trunk injection could decrease antibiotic usage in the open environment and increase the effectiveness of compounds in fire blight control. In field experiments, after 1-2 apple tree injections of either streptomycin, potassium phosphites (PH), or acibenzolar-S-methyl (ASM), significant reduction of blossom and shoot blight symptoms was observed compared to water injected control trees. Overall disease suppression with streptomycin was lower than typically observed following spray applications to flowers. Trunk injection of oxytetracycline resulted in excellent control of shoot blight severity, suggesting that injection is a superior delivery method for this antibiotic. Injection of both ASM and PH resulted in the significant induction of PR-1, PR-2, and PR-8 protein genes in apple leaves indicating induction of systemic acquired resistance (SAR) under field conditions. The time separating SAR induction and fire blight symptom suppression indicated that various defensive compounds within the SAR response were synthesized and accumulated in the canopy. ASM and PH suppressed fire blight even after cessation of induced gene expression. With the development of injectable formulations and optimization of doses and injection schedules, the injection of protective compounds could serve as an effective option for fire blight control.
Srđan G. Aćimović
Full Text Available Management of fire blight is complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. Even though successful in control, preventive antibiotic sprays also affect non-target bacteria, aiding the selection for resistance which could ultimately be transferred to the pathogen Erwinia amylovora. Trunk injection is a target-precise pesticide delivery method that utilizes tree xylem to distribute injected compounds. Trunk injection could decrease antibiotic usage in the open environment and increase the effectiveness of compounds in fire blight control. In field experiments, after 1-2 apple tree injections of either streptomycin, potassium phosphites (PH or acibenzolar-S-methyl (ASM, significant reduction of blossom and shoot blight symptoms was observed compared to water- or non-injected control trees. Overall disease suppression with streptomycin was lower than typically observed following spray applications to flowers. Trunk injection of oxytetracycline resulted in excellent control of shoot blight severity, suggesting that injection is a superior delivery method for this antibiotic. Injection of both ASM and PH resulted in the significant induction of PR-1, PR-2 and PR-8 protein genes in apple leaves indicating induction of systemic acquired resistance (SAR under field conditions. The time separating SAR induction and fire blight symptom suppression indicated that various defensive compounds within the SAR response were synthesized and accumulated in the canopy. ASM and PH suppressed fire blight even after cessation of induced gene expression. With the development of injectable formulations and optimization of doses and injection schedules, the injection of protective compounds could serve as an effective option for fire blight control.
National Aeronautics and Space Administration — ABSTRACT: This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax...
National Aeronautics and Space Administration — This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax (maximum...
Full Text Available Fire blight (FB, caused by Erwinia amylovora, is one of the most important pome fruit pathogens worldwide. To control this devastating disease, various chemical and biological treatments are commonly applied in Switzerland, but they fail to keep the infection at an acceptable level in years of heavy disease pressure. The Swiss authorities therefore currently allow the controlled use of the antibiotic streptomycin against FB in years that are predicted to have heavy infection periods, but only one treatment per season is permitted. Another strategy for controlling Erwinia is to breed resistant/tolerant apple cultivars. One way of accelerating the breeding process is to obtain resistant cultivars by inserting one or several major resistance genes, using genetic engineering. To date, no study summarizing the impact of different FB control measures on the environment and on human health has been performed. This study consequently aims to compare different disease-control measures (biological control, chemical control, control by antibiotics and by resistant/tolerant apple cultivars obtained through conventional or molecular breeding applied against E. amylovora, considering different protection goals (protection of human health, environment, agricultural diversity and economic interest, with special emphasis on biosafety aspects. Information on each FB control measure in relation to the specified protection goal was assessed by literature searches and by interviews with experts. Based on our results it can be concluded that the FB control measures currently applied in Switzerland are safe for consumers, workers and the environment. However, there are several gaps in our knowledge of the human health and environmental impacts analyzed: data are missing (1 on long term studies on the efficacy of most of the analyzed FB control measures; (2 on the safety of operators handling streptomycin; (3 on residue analyses of Equisetum plant extract, the copper
Full Text Available Banded leaf and sheath blight (BLSB and maydis leaf blight (MLB caused by Rhizoctonia solani and Bipolaris maydis, respectively are considered as important diseases in maize. The use of biopesticides is an alternative method to control the diseases. This study was conducted to determine the effectiveness of bacterial formula Bacillus subtilis to inhibit the development of BLSB and MLB on the plant. Testing of biopesticide formula was done in two different applications, i.e. seed treatment for BLSB control and leaf spraying in the field for MLB. The results showed that the B.subtilis formula effectively suppressed the development of BLSB but it was not effectively suppressed the development of MLB .Key words: Bacillus subtilis, biopesticide, Bipolaris maydis, leaf blight diseaseBanded leaf and sheath blight (BLSB and maydis leaf blight (MLB caused by Rhizoctonia solani and Bipolaris maydis, respectively are considered as important diseases in maize. The use of biopesticides is an alternative method to control the diseases. This study was conducted to determine the effectiveness of bacterial formula Bacillus subtilis to inhibit the development of BLSB and MLB on the plant. Testing of biopesticide formula was done in two different applications, i.e. seed treatment for BLSB control and leaf spraying in the field for MLB. The results showed that the B.subtilis formula effectively suppressed the development of BLSB but it was not effectively suppressed the development of MLB.
Full Text Available Phytophthora infestans (P. infestans is the causal agent of potato late blight, which caused the devastating Irish Potato Famine during 1845-1852. Until now, potato late blight is still the most serious threat to potato growth and has caused significant economic losses worldwide. Melatonin can induce plant innate immunity against pathogen infection, but the direct effects of melatonin on plant pathogens are poorly understood. In this study, we investigated the direct effects of melatonin on P. infestans. Exogenous melatonin significantly attenuated the potato late blight by inhibiting mycelial growth, changing cell ultrastructure, and reducing stress tolerance of P. infestans. Notably, synergistic anti-fungal effects of melatonin with fungicides on P. infestans suggest that melatonin could reduce the dose levels and enhance the efficacy of fungicide against potato late blight. A transcriptome analysis was carried out to mine downstream genes whose expression levels were affected by melatonin. The analysis of the transcriptome suggests that 66 differentially expressed genes involved in amino acid metabolic processes were significantly affected by melatonin. Moreover, the differentially expressed genes associated with stress tolerance, fungicide resistance, and virulence were also affected. These findings contribute to a new understanding of the direct functions of the melatonin on P. infestans and provide a potential ecofriendly biocontrol approach using a melatonin-based paradigm and application to prevent potato late blight.
Ian M. Haigh
Full Text Available Exposure to pre-emergent freezing temperatures significantly delayed the rate of seedling emergence (P<0.05 from an infected and a non-infected winter wheat cv. Equinox seed lot, but significant effects for timing of freezing and duration of freezing on final emergence were only seen for the Microdochium-infested seed lot. Freezing temperatures of −5∘C at post-emergence caused most disease on emerged seedlings. Duration of freezing (12 hours or 24 hours had little effect on disease index but exposure to pre-emergent freezing for 24 hours significantly delayed rate of seedling emergence and reduced final emergence from the infected seed lot. In plate experiments, the calculated base temperature for growth of M. nivale and M. majus was −6.3∘C and −2.2∘C, respectively. These are the first set of experiments to demonstrate the effects of pre-emergent and post-emergent freezing on the severity of Microdochium seedling blight.
Jayaswall, Kuldip; Mahajan, Pallavi; Singh, Gagandeep; Parmar, Rajni; Seth, Romit; Raina, Aparnashree; Swarnkar, Mohit Kumar; Singh, Anil Kumar; Shankar, Ravi; Sharma, Ram Kumar
To unravel the molecular mechanism of defense against blister blight (BB) disease caused by an obligate biotrophic fungus, Exobasidium vexans, transcriptome of BB interaction with resistance and susceptible tea genotypes was analysed through RNA-seq using Illumina GAIIx at four different stages during ~20-day disease cycle. Approximately 69 million high quality reads were assembled de novo, yielding 37,790 unique transcripts with more than 55% being functionally annotated. Differentially expressed, 149 defense related transcripts/genes, namely defense related enzymes, resistance genes, multidrug resistant transporters, transcription factors, retrotransposons, metacaspases and chaperons were observed in RG, suggesting their role in defending against BB. Being present in the major hub, putative master regulators among these candidates were identified from predetermined protein-protein interaction network of Arabidopsis thaliana. Further, confirmation of abundant expression of well-known RPM1, RPS2 and RPP13 in quantitative Real Time PCR indicates salicylic acid and jasmonic acid, possibly induce synthesis of antimicrobial compounds, required to overcome the virulence of E. vexans. Compendiously, the current study provides a comprehensive gene expression and insights into the molecular mechanism of tea defense against BB to serve as a resource for unravelling the possible regulatory mechanism of immunity against various biotic stresses in tea and other crops.
Full Text Available Potato late blight (PLB caused by Phytophthora infestans (Pi is the most harmful disease in potato production worldwide. In organic farming, copper is used despite its persistence in soil and toxicity to soil organisms. To replace copper, suspensions of powders from three promising botanicals, including bark of buckthorn (Frangula alnus, FA, roots of medicinal rhubarb (Rheum palmatum and galls of the nutgall tree (Galla chinensis, were tested in multi-year field experiments. The current study shows for the first time that botanicals could replace copper under field conditions and best PLB reduction on leaves was achieved with FA, reaching a level close to that of 2 to 3 kg copper per hectare and year. Better results than with copper were achieved with Phosfik® (Ph, a phosphonate-based product. For both FA and Ph, the mode of action is based on induced resistance, for Ph also on direct fungicidal effects. A disadvantage of Ph is the accumulation of residues in potato tubers. Nevertheless, two to three applications with 2 to 3 L/ha of Ph would be feasible to not exceed a minimal risk level (MLR of 20 mg/kg of phosphorous acid as proposed by the European Food Safety Authority. Due to an excellent environmental profile and a complex mode of action counteracting Pi resistance, phosphonate-based products would be most suitable for sustainable PLB management in integrated pest management (IPM programmes.
Ježić, Marin; Mlinarec, Jelena; Vuković, Rosemary; Katanić, Zorana; Krstin, Ljiljana; Nuskern, Lucija; Poljak, Igor; Idžojtić, Marilena; Tkalec, Mirta; Curkovic-Perica, Mirna
Invasive species, especially plant pathogens have a potential to completely eradicate native plant species and remodel landscapes. Tripartite interaction among sweet chestnut, Castanea sativa, chestnut blight-causing invasive fungus, Cryphonectria parasitica, and a hyperparasitic virus, Cryphonectria parasitica hypovirus 1 (CHV1) were studied in two populations. The number of different vegetative compatibility (vc) types of C. parasitica more than doubled over the ten years, while the hypovirulence incidence dropped in one population, and slightly increased in the other one. Over the course of our short term, three year monitoring experiment, the prevalence of hypovirulent isolates obtained from monitored cankers increased slowly, i.e. more hypovirulent isolates were being obtained from the same cankers over time. Within studied cankers considerable changes in vc type and CHV1 presence were observed, indicating a highly dynamic system in which virulent and hypovirulent mycelia, sometimes of discordant vc types, often appeared together. The increase in hypovirulence prevalence did not have any observable curative effect on the cankers, and occasionally reactivation of healed cankers by new, virulent C. parasitica isolates was observed. Both, short and long term observations and revalidation of the infected plant populations are necessary to accurately estimate disease progress and formulate an adequate disease management strategy.
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.
Chetouhi, Cherif; Bonhomme, Ludovic; Lecomte, Philippe; Cambon, Florence; Merlino, Marielle; Biron, David Georges; Langin, Thierry
The mycotoxigenic fungal species Fusarium graminearum is able to attack several important cereal crops, such as wheat and barley. By causing Fusarium Head Blight (FHB) disease, F. graminearum induces yield and quality losses and poses a public health concern due to in planta mycotoxin production. The molecular and physiological plant responses to FHB, and the cellular biochemical pathways used by F. graminearum to complete its infectious process remain still unknown. In this study, a proteomics approach, combining 2D-gel approach and mass spectrometry, has been used to determine the specific protein patterns associated with the development of the fungal infection during grain growth on susceptible wheat. Our results reveal that F. graminearum infection does not deeply alter the grain proteome and does not significantly disturb the first steps of grain ontogeny but impacts molecular changes during the grain filling stage (impact on starch synthesis and storage proteins). The differentially regulated proteins identified were mainly involved in stress and defence mechanisms, primary metabolism, and main cellular processes such as signalling and transport. Our survey suggests that F. graminearum could take advantage of putative susceptibility factors closely related to grain development processes and thus provide new insights into key molecular events controlling the susceptible response to FHB in wheat grains.
Shabanamol, S; Sreekumar, J; Jisha, M S
The present study tried to explore the possible in vitro biocontrol mechanisms of Lysinibacillus sphaericus , a diazotrophic endophyte from rice against the rice sheath blight pathogen Rhizoctonia solani. The in vivo biocontrol potential of the isolate and the induction of systemic resistance under greenhouse conditions have also been experimented employing different treatments with positive control carbendazim, the chemical fungicide. The endophytic isolate showed 100% growth inhibition of the fungal pathogen via volatile organic compound production and was positive for the production of siderophores, biosurfactants, HCN, and ammonia. Under greenhouse conditions, foliar and soil application of L. sphaericus significantly decreased the percentage of disease incidence. All bacterized treatments are superior to chemical fungicide treatment. Application of L. sphaericus in single and combination treatments induces systemic resistance as evident from the significant accumulation of defense enzymes such as peroxides, polyphenol oxides and phenylalanine ammonia in addition to the increase of phenolic compounds. The results biologically prospect endophytic diazotroph L. sphaericus as a potent plant growth promoter with excellent biocontrol efficiency.
Full Text Available A diagnostic method based on nested-PCR, followed by ELISA and conventional bacteriology tests, for the rapid and reliable detection of halo blight pathogen Pseudomonas savastanoi pv. phaseolicola (Psp collected from infected bean leaves and seeds is described. Psp formed white, small and flat colonies on nutrient agar medium, creamy white, flat and circular on Milk-Tween agar medium and light yellow, convex and shiny on modified sucrose peptone agar medium. Eighteen Gram-negative, catalase-positive and oxidase-negative strains were subjected to nested PCR with primers P 5.1/P 3.1 and P 5.2/P 3.2, which directed the amplification of the 450 bp target DNA fragment in all tested strains. According to the results of DAS- and PTA-ELISA with respect to reactivity to specific antibodies, all analyzed strains belonged to Psp bacterium. Pathogenicity was tested on bean pods and cotyledon leaves, on which greasy spots were formed. Psp did not cause hypersensitive reaction on the leaves of tobacco and geranium. Strains produced levan, fluorescent pigment, oxidative metabolism of glucose, did not reduce nitrate, did not produce indole and H2S, did not hydrolyze starch, gelatin and esculin; they produced acid from glucose, mannose, sucrose and glycerol, and did not produce acid from maltose, starch, esculin, dulcite, sorbitol, inositol and erythritol.
The most prolific of Darwin's correspondents from Ireland was James Torbitt, an enterprising grocer and wine merchant of 58 North Street, Belfast. Between February 1876 and March 1882, 141 letters were exchanged on the feasibility and ways of supporting one of Torbitt's commercial projects, the large-scale production and distribution of true potato seeds (Solan um tuberosum) to produce plants resistant to the late blight fungus Phytophthora infestans, the cause of repeated potato crop failures and thus the Irish famines in the nineteenth century. Ninety-three of these letters were exchanged between Torbitt and Darwin, and 48 between Darwin and third parties, seeking or offering help and advice on the project. Torbitt's project required selecting the small proportion of plants in an infested field that survived the infection, and using those as parents to produce seeds. This was a direct application of Darwin's principle of selection. Darwin cautiously lobbied high-ranking civil servants in London to obtain government funding for the project, and also provided his own personal financial support to Torbit.
Full Text Available Suspensions or solutions with 1% of Chinese galls (Galla chinensis, GC or 1% of tannic acid (TA, inhibited germination of conidia or mycelium growth of Fusarium graminearum (FG by 98%–100% or by 75%–80%, respectively, whereas dried bark from buckthorn (Frangula alnus, FA showed no effect at this concentration. In climate chamber experiments where the wheat variety “Apogee” was artificially inoculated with FG and F. crookwellense (FCr and treated with 5% suspensions of TA, GC and FA, the deoxynivalenol (DON content in grains was reduced by 81%, 67% and 33%, respectively. In field experiments with two commercial wheat varieties and artificial or semi-natural inoculations, mean DON reductions of 66% (TA and 58% (FA, respectively, were obtained. Antifungal toxicity can explain the high efficacies of TA and GC but not those of FA. The Fusarium head blight (FHB and mycotoxin reducing effect of FA is probably due to elicitation of resistance in wheat plants. With semi-natural inoculation, a single FA application in the first half of the flowering period performed best. However, we assume that applications of FA at the end of ear emergence and a treatment, triggered by an infection period, with TA or GC during flowering, might perform better than synthetic fungicides.
Alexandre A. Oliveira
Full Text Available Botrytis blight or gray mold is a highly destructive disease caused by Botrytis spp., that infects flowers, trees vegetables, fruit, especially grapevines and strawberry. Three new compounds with general formula (A2[Zn(4-FC6H4SO2N=CS22], where A = PPh3CH3 (2a, PPh3C2H5 (2b, PPh3C4H9 (2c, and the previously published compounds where A = PPh4 (2d and NBu4 (2e, were synthesized by the reaction of 4-fluorophenylsulfonyldithiocarbimate potassium dihydrate and zinc(II acetate dihydrate with the appropriate counter cations (A halides. The new compounds were characterized by infrared, 1H and 13C NMR spectroscopies. All these salts inhibited the growth of Botrytis cinerea, with compounds 2c and 2d showing greater antifungal activity than zinc dimethyldithiocarbamate, the active principle of the fungicide Ziram. The bis(dithiocarbimatezincate(II salts are also active against the bacteria Escherichia coli and Staphylococcus aureus.
Minocha, J.L.; Das, A.; Gopal, J.; Gosal, S.S.
In vitro plants were obtained from nodal sections of sprouts of cvs. 'Kufri Jyoti' and 'Kufri Chandramukhi' of potato cultured on MS medium with 3% sucrose. Callus from leaves of in vitro cultured plantlets was induced on modified Linsmaier and Skoog medium supplemented with 5 mg/1 NAA. The obtained shoots and calli were irradiated with 20 and 40 Gy gamma rays. Irradiatied shoots were transferred to MS medium with 8% sucrose for multiplication, and then to MS medium with 8% sucrose and 10 mg/1 BAP to induce microtuber formation, which gave on average 1.3 microtubers per plant. The microtubers were planted in pots and variation was observed in plant morphology and tuber characters. To study variation for late blight resistance, irradiated calli were kept on Gamborg B-5 medium with culture filtrate of Phytophthora infestans. To induce variation for heat tolerance, in vitro shoots from irradiated material were mass-propagated and allowed to produce microtubers at high temperature. (author). 3 refs, 3 tabs
Kalih, R; Maurer, H P; Miedaner, T
Fusarium head blight (FHB) is a devastating disease that causes significant reductions in yield and quality in wheat, rye, and triticale. In triticale, knowledge of the genetic architecture of FHB resistance is missing but essential due to modern breeding requirements. In our study, four doubled-haploid triticale populations (N=120 to 200) were evaluated for resistance to FHB caused by artificial inoculation with Fusarium culmorum in four environments. DArT markers were used to genotype triticale populations. Seventeen quantitative trait loci (QTL) for FHB resistance were detected across all populations; six of them were derived from rye genome and located on chromosomes 4R, 5R, and 7R, which are here reported for the first time. The total cross-validated ratio of the explained phenotypic variance for all detected QTL in each population was 41 to 68%. In all, 17 QTL for plant height and 18 QTL for heading stage were also detected across all populations; 3 and 5 of them, respectively, were overlapping with QTL for FHB. In conclusion, FHB resistance in triticale is caused by a multitude of QTL, and pyramiding them contributes to higher resistance.
Marzano, Mariella; Fuller, Lauren; Quine, Christopher P
Forest Managers in the UK and elsewhere are facing new threats such as climate change and novel pests and diseases. Strategies seek to coordinate and steer appropriate responses through raising awareness and encouraging action but little is known about how individual managers respond to disease threats. We studied how managers have responded to the threat of Dothistroma Needle Blight (DNB), a disease which can affect growth and cause mortality of many pine species, and the key frames influencing their responses. Frames involve values and beliefs and allow people to make sense of, and interpret, events, experiences or issues. Interviews revealed broad awareness of the disease and threat it poses, but also high levels of inaction. Lack of action was associated with several framings grouped around causes and perceived severity of DNB, locating responsibility for prevention and management, mistrust/scepticism of advice and uncertainties over the future impact. These framings need to be considered as strategies are refined and new knowledge of disease behaviour is communicated to those from whom action is required. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.
Yan, En-Rong; Milla, Rubén; Aarssen, Lonnie W.; Wang, Xi-Hua
Leafing intensity, i.e. the number of leaves per unit of stem volume or mass, is a common developmental correlate of leaf size. However, the ecological significance and the functional implications of variation in leafing intensity, other than its relation to leaf size, are unknown. Here, we explore its relationships with plant height, growth form, leaf size, and leaf habit to test a series of corollaries derived from the leafing intensity premium hypothesis. Volume-based leafing intensities and plant heights were recorded for 109 woody species from the subtropical evergreen broadleaf forests of eastern China. In addition, we compiled leafing intensity data from published literature, and combined it with our data to form a 398 species dataset, to test for differences of leafing intensity between plant growth forms (i.e. herbaceous and woody) and leaf habits (i.e. deciduous and evergreens). Leafing intensity was negatively correlated with plant height and individual leaf mass. Volume-based leafing intensities were significantly higher in herbaceous species than in woody species, and also higher in deciduous than in evergreen woody species. In conclusion, leafing intensity relates strongly to plant height, growth form, leaf size, and leaf habit in directions generally in accordance to the leafing intensity premium hypothesis. These results can be interpreted in terms of the evolution of adaptive strategies involving response to herbivory, competitive ability for light and reproductive economy.
Doug P. Aubrey; Stephen W. Fraedrich; Thomas C. Harrington; Rabiu Olatinwo
We report the association of Cristulariella moricola (Hino) Redhead with a zonate leaf spot on Eucalyptus benthamii (Myrtaceae). We observed the disease outbreak across a series of experimental E. benthamii plantings in Barnwell County, South Carolina, USA in October 2015. The disease caused nearly complete foliar necrosis of most trees in one experimental planting,...
Dong, N.; Prentice, I. C.; Wright, I. J.
In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf
Simmons, Christopher W; Nitin, N; Vandergheynst, Jean S
Attachment of the plant pathogen Agrobacterium tumefaciens to host plant cells is an early and necessary step in plant transformation and agroinfiltration processes. However, bacterial attachment behavior is not well understood in complex plant tissues. Here we developed an imaging-based method to observe and quantify A. tumefaciens attached to leaf tissue in situ. Fluorescent labeling of bacteria with nucleic acid, protein, and vital dyes was investigated as a rapid alternative to generating recombinant strains expressing fluorescent proteins. Syto 16 green fluorescent nucleic acid stain was found to yield the greatest signal intensity in stained bacteria without affecting viability or infectivity. Stained bacteria retained the stain and were detectable over 72 h. To demonstrate in situ detection of attached bacteria, confocal fluorescent microscopy was used to image A. tumefaciens in sections of lettuce leaf tissue following vacuum-infiltration with labeled bacteria. Bacterial signals were associated with plant cell surfaces, suggesting detection of bacteria attached to plant cells. Bacterial attachment to specific leaf tissues was in agreement with known leaf tissue competencies for transformation with Agrobacterium. Levels of bacteria attached to leaf cells were quantified over time post-infiltration. Signals from stained bacteria were stable over the first 24 h following infiltration but decreased in intensity as bacteria multiplied in planta. Nucleic acid staining of A. tumefaciens followed by confocal microscopy of infected leaf tissue offers a rapid, in situ method for evaluating attachment of A. tumefaciens' to plant expression hosts and a tool to facilitate management of transient expression processes via agroinfiltration. Copyright © 2012 American Institute of Chemical Engineers (AIChE).
Sharma, Mamta; Ghosh, Raju; Tarafdar, Avijit; Telangre, Rameshwar
Phytophthora blight caused by Phytophthora cajani is an emerging disease of pigeonpea (Cajanus cajan L.) affecting the crop irrespective of cropping system, cultivar grown and soil types. Current detection and identification methods for Phytophthora species rely primarily on cultural and morphological characteristics, the assessment of which is time-consuming and not always suitable. Sensitive and reliable methods for isolation, identification, zoospore production and estimating infection severity are therefore desirable in case of Phytophthora blight of pigeonpea. In this study, protocols for isolation and identification of Phytophthora blight of pigeonpea were standardized. Also the method for zoospore production and in planta infection of P. cajani was developed. Quantification of fungal colonization by P. cajani using real-time PCR was further standardized. Phytophthora species infecting pigeonpea was identified based on mycological characters such as growth pattern, mycelium structure and sporangial morphology of the isolates and confirmed through molecular characterization (sequence deposited in GenBank). For Phytophthora disease development, zoospore suspension of 1 × 10(5) zoospores per ml was found optimum. Phytophthora specific real-time PCR assay was developed using specific primers based on internal transcribed spacer (ITS) 1 and 2. Use of real-time PCR allowed the quantitative estimation of fungal biomass in plant tissues. Detection sensitivities were within the range of 0.001 pg fungal DNA. A study to see the effect of elevated CO₂ on Phytophthora blight incidence was also conducted which indicated no significant difference in disease incidence, but incubation period delayed under elevated CO₂ as compared to ambient level. The zoospore infection method for Phytophthora blight of pigeonpea will facilitate the small and large scale inoculation experiments and thus devise a platform for rapid and reliable screening against Phytophthora blight
Ferrada, Enrique E; Latorre, Bernardo A; Zoffoli, Juan P; Castillo, Antonio
Blossom blight is a destructive disease of plums (Prunus salicina) when humid and temperate weather conditions occur in Chile. Disease incidence ranging from 4 to 53% has been observed. Symptoms include light brown petal necrosis, starting as light brown mottles or V-shaped necrosis at the margins of the petals, progressing to the stamen and pistils. In this study, the etiology of blossom blight of plums was determined. High- and low-sporulating isolates of Botrytis were obtained consistently from blighted blossoms and apparently healthy flowers of plums. Based on colony morphology, conidial production and molecular phylogenetic analysis, these high- and low-sporulating isolates were identified as B. cinerea and B. prunorum sp. nov., respectively. Phylogenetic analysis of the genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) grouped B. prunorum isolates in a single cluster, distantly from B. cinerea and other Botrytis species. The phylogenetic analysis of necrosis and ethylene-inducing protein (NEP1 and NEP2) genes corroborated these results. Analysis of the internal transcribed spacer region and large-subunit (26S) ribosomal DNA and detection of Boty and Flipper transposable elements, were not useful to differentiate between these Botrytis species. Both species were pathogenic on plum flowers and the fruit of plums, apples, and kiwifruits. However, B. prunorum was less virulent than B. cinerea. These pathogens were re-isolated from inoculated and diseased tissues; thus, Koch's postulates were fulfilled, confirming its role in blossom blight of plums. B. cinerea was predominant, suggesting that B. prunorum may play a secondary role in the epidemiology of blossom blight in plums in Chile. This study clearly demonstrated that the etiology of blossom blight of plums is caused by B. cinerea and B. prunorum, which constitute a species complex living in sympatry on plums and possibly
Sliwka, J; Jakuczun, H; Lebecka, R; Marczewski, W; Gebhardt, C; Zimnoch-Guzowska, E
Phytophthora infestans causes an economically important disease of potato called late blight. The epidemic is controlled chemically but resistant potatoes can become an environment-friendly and financially justified alternative solution. The use of diploid Solanum tuberosum derived from European tetraploid cultivars enabled the introgression of novel genes encoding foliage resistance and tuber resistance from other species into the modern cultivated potato gene pool. This study evaluated the resistance of the obtained hybrids, its quality, expression in leaflets and tubers and its relation to the length of vegetation period. We also identified genetic loci involved in late blight resistance and the length of vegetation period. A family of 156 individuals segregating for resistance to late blight was assessed by three laboratory methods: detached leaflet, tuber slice and whole tuber test, repeatedly over 5 years. Length of vegetation period was estimated by a field test over 2 years. The phenotypic distributions of all traits were close to normal. Using sequence-specific PCR markers of known chromosomal position on the potato genetic map, six quantitative trait loci (QTLs) for resistance and length of vegetation period were identified. The most significant and robust QTL were located on chromosomes III (explaining 17.3% of variance observed in whole tuber tests), IV (15.5% of variance observed in slice tests), X (15.6% of variance observed in leaflet tests) and V (19.9% of variance observed in length of vegetation period). Genetic characterization of these novel resistance sources can be valuable for potato breeders and the knowledge that the most prominent QTLs for resistance and vegetation period length do not overlap in this material is promising with respect to breeding early potatoes resistant to P. infestans.
В. В. Гордієнко
Full Text Available Purpose. To select the initial breeding material with complex resistance to Fusarium dry rot and tuber late blight among the created potato of secondary interspecific hybrids. Methods. Interspecific hybridization, laboratory test, analytical approach. Results. Based on the interspecific hybridization, the initial breeding material was created and the degree of its resistance to the above pathogens was determined by way of artificial infection of tubers with the inoculum of such fungi as Fusarium sambucinum Fuck and Phytophthora infestans (Mont. De Bary. During interspecific hybridization based on schemes of saturating and enriching crosses, using forms of various species with a high phenotypic expression of resistance to Fusarium dry rot, the result of the cumulative effect of genes that control resistance to the pathogen was observed. Crossing combinations differed significantly for the degree of population average manifestation of resistance to the diseases. Conclusions. Combinations В54, В53, В61 with a mean resistance (above 7 grades to Fusarium dry rot have been selected. Such combinations as B52, B50 and B54 had increased resistance to tuber late blight. It was found that the combination В54 is characterized by complex resistance to both diseases. For further work, the following samples with complex resistance to Fusarium dry rot and tuber late blight (7 grades or more were selected: В59с42, В59с43, В50с16, В50с19, В50с44, В51с1, В51с26, В51с28, В52с11, В52с23, В52с24, В52с29, В53с1, В53с11, В53с17 , В53с23, В54с13, В54с14.
Marcio P. Arruda
Full Text Available Genomic selection (GS is a breeding method that uses marker–trait models to predict unobserved phenotypes. This study developed GS models for predicting traits associated with resistance to head blight (FHB in wheat ( L.. We used genotyping-by-sequencing (GBS to identify 5054 single-nucleotide polymorphisms (SNPs, which were then treated as predictor variables in GS analysis. We compared how the prediction accuracy of the genomic-estimated breeding values (GEBVs was affected by (i five genotypic imputation methods (random forest imputation [RFI], expectation maximization imputation [EMI], -nearest neighbor imputation [kNNI], singular value decomposition imputation [SVDI], and the mean imputation [MNI]; (ii three statistical models (ridge-regression best linear unbiased predictor [RR-BLUP], least absolute shrinkage and operator selector [LASSO], and elastic net; (iii marker density ( = 500, 1500, 3000, and 4500 SNPs; (iv training population (TP size ( = 96, 144, 192, and 218; (v marker-based and pedigree-based relationship matrices; and (vi control for relatedness in TPs and validation populations (VPs. No discernable differences in prediction accuracy were observed among imputation methods. The RR-BLUP outperformed other models in nearly all scenarios. Accuracies decreased substantially when marker number decreased to 3000 or 1500 SNPs, depending on the trait; when sample size of the training set was less than 192; when using pedigree-based instead of marker-based matrix; or when no control for relatedness was implemented. Overall, moderate to high prediction accuracies were observed in this study, suggesting that GS is a very promising breeding strategy for FHB resistance in wheat.
Saville, Amanda C; Martin, Michael D; Ristaino, Jean B
Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, was responsible for the Irish potato famine of the 1840s. Initial disease outbreaks occurred in the US in 1843, two years prior to European outbreaks. We examined the evolutionary relationships and source of the 19th-century outbreaks using herbarium specimens of P. infestans from historic (1846-1970) and more recent isolates (1992-2014) of the pathogen. The same unique SSR multilocus genotype, named here as FAM-1, caused widespread outbreaks in both US and Europe. The FAM-1 lineage shared allelic diversity and grouped with the oldest specimens collected in Colombia and Central America. The FAM-1 lineage of P. infestans formed a genetic group that was distinct from more recent aggressive lineages found in the US. The US-1 lineage formed a second, mid-20th century group. Recent modern US lineages and the oldest Mexican lineages formed a genetic group with recent Mexican lineages, suggesting a Mexican origin of recent US lineages. A survey of mitochondrial haplotypes in a larger set of global herbarium specimens documented the more frequent occurrence of the HERB-1 (type Ia) mitochondrial haplotype in archival collections from 1866-75 and 1906-1915 and the rise of the Ib mitochondrial lineage (US-1) between 1946-1955. The FAM-1 SSR lineage survived for almost 100 years in the US, was geographically widespread, and was displaced first in the mid-20th century by the US-1 lineage and then by distinct new aggressive lineages that migrated from Mexico.
Ambuj B. Jha
Full Text Available Ascochyta blight (AB is an important disease of pea which can cause severe grain yield loss under wet conditions. In our previous study, we identified two quantitative trait loci (QTLs abIII-1 and abI-IV-2 for AB resistance and these QTLs were consistent across locations and/or years in an inter-specific pea population (PR-19 developed from a cross between Alfetta (Pisum sativum and P651 (P. fulvum. The objectives of this study were to fine map the abIII-1 and abI-IV-2 QTLs using a high density single nucleotide polymorphism (SNP-based genetic linkage map and analyze identified markers in heterogeneous inbred family (HIF populations. Selective genotyping of 51 PR-19 recombinant inbred lines was performed using genotyping-by-sequencing (GBS and the resulting high density genetic linkage map was used to identify eight new SNP markers within the abI-IV-2 QTL, whereas no additional SNPs were identified within the abIII-1 QTL. Two HIF populations HIF-224 (143 lines and HIF-173 (126 lines were developed from F6 RILs PR-19-224 and PR-19-173, respectively. The HIF populations evaluated under field conditions in 2015 and 2016 showed a wide range of variation for reaction to AB resistance. Lodging score had significant positive (P < 0.001 correlation with AB scores. HIFs were genotyped using SNP markers within targeted QTLs. The genotypic and phenotypic data of the HIFs were used to identify two new QTLs, abI-IV-2.1 and abI-IV-2.2 for AB resistance within the abI-IV-2 QTL. These QTLs individually explained 5.5 to 14% of the total phenotypic variation. Resistance to lodging was also associated with these two QTLs. Identified SNP markers will be useful in marker assisted selection for development of pea cultivars with improved AB resistance.
Klemm, Per; Vejborg, Rebecca Munk; Hancock, Viktoria
Management of bacterial infections is becoming increasingly difficult due to the emergence and increasing prevalence of bacterial pathogens that are resistant to available antibiotics. Conventional antibiotics generally kill bacteria by interfering with vital cellular functions, an approach...... that imposes selection pressure for resistant bacteria. New approaches are urgently needed. Targeting bacterial virulence functions directly is an attractive alternative. An obvious target is bacterial adhesion. Bacterial adhesion to surfaces is the first step in colonization, invasion, and biofilm formation....... As such, adhesion represents the Achilles heel of crucial pathogenic functions. It follows that interference with adhesion can reduce bacterial virulence. Here, we illustrate this important topic with examples of techniques being developed that can inhibit bacterial adhesion. Some of these will become...
... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...
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... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its...
Banu, Tahmina; Talukder, Rupom; Chowdhury, Tanvir Kabir; Hoque, Mozammel
Construction of a stoma is a common procedure in pediatric surgical practice. For care of these stomas, commercially available devices such as ostomy bag, either disposable or of longer duration are usually used. These are expensive, particularly in countries like Bangladesh, and proper-sized ones are not always available. We have found an alternative for stoma care, betel leaf, which is suitable for Bangladeshis. We report the outcome of its use. After construction of stoma, at first zinc oxide paste was applied on the peristomal skin. A betel leaf with shiny, smooth surface outwards and rough surface inwards was put over the stoma with a hole made in the center according to the size of stoma. Another intact leaf covers the stomal opening. When bowel movement occurs, the overlying intact leaf was removed and the fecal matter was washed away from both. The leaves were reused after cleaning. Leaves were changed every 2 to 3 days. From June 1998 to December 2005, in the department of pediatric surgery, Chittagong Medical College and Hospital, Chittagong, Bangladesh, a total of 623 patients had exteriorization of bowel. Of this total, 495 stomas were cared for with betel leaves and 128 with ostomy bags. Of 623 children, 287 had sigmoid colostomy, 211 had transverse colostomy, 105 had ileostomy, and 20 had jejunostomy. Of the 495 children under betel leaf stoma care, 13 patients (2.6%) developed skin excoriation. There were no allergic reactions. Of the 128 patients using ostomy bag, 52 (40.65%) had skin excoriation. Twenty-four (18.75%) children developed some allergic reactions to adhesive. Monthly costs for betel leaves were 15 cents (10 BDT), whereas ostomy bags cost about US$24. In the care of stoma, betel leaves are cheap, easy to handle, nonirritant, and nonallergic.
... 7 Agriculture 2 2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than Leaf...
Ruetz, C. R.; Vanhaitsma, D. L.; Breen, M. J.
We investigated two attributes of leaf-pack complexity (i.e., leaf-pack mass and leaf surface area) on fish predation, colonization of benthic macroinvertebrates, and leaf breakdown rates in a coldwater Michigan stream. We manipulated three factors using a factorial design: fish (exclusion or control cage), leaf-pack mass (1, 3, or 5 g dry mass), and leaf surface area (10 cm leaf width). Acer leaves were fastened into leaf packs. Exclusion cages had mesh on all sides; control cages lacked mesh on two sides to provide access to fishes. Two replicate leaf packs were randomly collected after 25-31 d from two sections of the stream (n = 4). Common shredders were Gammarus, Pycnopsyche, and Lepidostoma. We did not detect a significant effect of fish predation on benthic macroinvertebrates or leaf breakdown (i.e., mass loss). Colonization of benthic macroinvertebrates appeared proportional to leaf-pack mass but was unaffected by the surface area of leaves. Leaf breakdown was more rapid among leaf packs with fewer leaves (i.e., leaves with large surface area and leaf packs with low mass) and greater numbers of shredders. We suspect that physical fragmentation is the primary mechanism for higher breakdown rates among leaf packs with fewer leaves.
Le May, Christophe; Guibert, Michèle; Leclerc, Aurélie; Andrivon, Didier; Tivoli, Bernard
Plant diseases are caused by pathogen populations continuously subjected to evolutionary forces (genetic flow, selection, and recombination). Ascochyta blight, caused by Mycosphaerella pinodes, is one of the most damaging necrotrophic pathogens of field peas worldwide. In France, both winter and spring peas are cultivated. Although these crops overlap by about 4 months (March to June), primary Ascochyta blight infections are not synchronous on the two crops. This suggests that the disease could be due to two different M. pinodes populations, specialized on either winter or spring pea. To test this hypothesis, 144 pathogen isolates were collected in the field during the winter and spring growing seasons in Rennes (western France), and all the isolates were genotyped using amplified fragment length polymorphism (AFLP) markers. Furthermore, the pathogenicities of 33 isolates randomly chosen within the collection were tested on four pea genotypes (2 winter and 2 spring types) grown under three climatic regimes, simulating winter, late winter, and spring conditions. M. pinodes isolates from winter and spring peas were genetically polymorphic but not differentiated according to the type of cultivars. Isolates from winter pea were more pathogenic than isolates from spring pea on hosts raised under winter conditions, while isolates from spring pea were more pathogenic than those from winter pea on plants raised under spring conditions. These results show that disease developed on winter and spring peas was initiated by a single population of M. pinodes whose pathogenicity is a plastic trait modulated by the physiological status of the host plant.
Hossain, Md Kamal; Jena, Kshirod; Bhuiyan, Md Atiqur Rahman; Ratnam, Wickneswari
Sheath blight is an emerging threat in rice cultivation. It is animportant disease caused by the soil-borne necrotrophic pathogenic fungus, Rhizoctonia solani Kühn. However, to date neither known major genes for quantitative resistance, nor any rice lines immune to this disease has been identified. The disease resistance is quantitative in nature. Numerous genes are involved in this resistance process. There are few quantitative trait loci (QTLs) detected conferring improved resistance against the disease. Teqing and Tetepshowimproved resistance having QTLs, qSB-9 and qSBR11-1, respectively. Since, these QTLs demonstrates additive effects, pyramiding of these QTLs might be an option to increase the sheath blight resistance in rice. Nine rice cultivars were screened at greenhouse conditions. Results showed that Tetep and Teqing had the lowest disease ratings. UKMRC2a new high yielding cultivar was as recipient parent. Crosses between UKMRC2 and Teqing, and UKMRC2 and Tetep were made and confirmed. Subsequently 4-way crosses between the two F1s were performed to develop pyramidal lines.
Miedaner, Thomas; Schulthess, Albert W; Gowda, Manje; Reif, Jochen C; Longin, C Friedrich H
Mid-parent values of Fusarium head blight (FHB) resistance tested across several locations are a good predictor of hybrid performance caused by a preponderance of additive gene action in wheat. Hybrid breeding is intensively discussed as one solution to boost yield and yield stability including an enhanced biotic stress resistance. Our objectives were to investigate (1) the heterosis for Fusarium head blight (FHB) resistance, (2) the importance of general (GCA) vs. specific combining ability (SCA) for FHB resistance, and (3) the possibility to predict the FHB resistance of the hybrids by the parental means. We re-analyzed phenotypic data of a large population comprising 1604 hybrids and their 120 female and 15 male parental lines evaluated in inoculation trials across seven environments. Mid-parent heterosis of FHB severity averaged -9%, with a range from -36 to +35%. Mean better parent heterosis was 2% and 78 of the hybrids significantly (P hybrids (r = 0.09, P hybrid performance of FHB severity based on mid-parent values and on GCA effects was high (r = 0.70 and 0.86, respectively; P hybrids are an attractive alternative variety type to improve FHB resistance.
Darge Wendu Admasu
Full Text Available Canker and needle blight of Araucaria heterophylla (Norfolk Island pine trees were observed during the surveys conducted in Addis Ababa and Adama cities (Ethiopia from November to December 2016. The main objective of this study was to investigate fungal pathogens that cause diseases on Araucaria heterophylla trees. Six localities with Araucaria heterophylla plantings were purposively surveyed for disease symptoms. Samples from symptomatic parts of trees were collected, surface sterilized, cultured on PDA and morphologically identified for genus and species. A total of 36 isolates of fungi were identified. Based on macro- and microscopic morphological features of the colonies, the fungal isolates were found to be the genus Diplodia and species Lasiodiplodia theobromae (Pat. Griffon & Maubl (syn. Botryodiplodia theobromae, the anamorph of Botryosphaeria rhodina (Berk. & M.A. Curtis Arx. The pathogenicity test showed that the isolates of Lasiodiplodia theobromae, caused stem canker and needle blight on Araucaria heterophylla. This finding is important in the study of management options for future prevention and control of diseases in the country.
Full Text Available Abstract Background Mechanisms involved in the biological control of plant diseases are varied and complex. Hormones, including the auxin indole acetic acid (IAA and abscisic acid (ABA, are essential regulators of a multitude of biological functions, including plant responses to biotic and abiotic stressors. This study set out to determine what hormones might play a role in Pseudomonas fluorescens –mediated control of Fusarium head blight (FHB disease of barley and to determine if biocontrol-associated hormones directly affect disease development. Results A previous study distinguished bacterium-responsive genes from bacterium-primed genes, distinguished by the fact that the latter are only up-regulated when both P. fluorescens and the pathogen Fusarium culmorum are present. In silico analysis of the promoter sequences available for a subset of the bacterium-primed genes identified several hormones, including IAA and ABA as potential regulators of transcription. Treatment with the bacterium or pathogen resulted in increased IAA and ABA levels in head tissue; both microbes had additive effects on the accumulation of IAA but not of ABA. The microbe-induced accumulation of ABA preceded that of IAA. Gene expression analysis showed that both hormones up-regulated the accumulation of bacterium-primed genes. But IAA, more than ABA up-regulated the transcription of the ABA biosynthesis gene NCED or the signalling gene Pi2, both of which were previously shown to be bacterium-responsive rather than primed. Application of IAA, but not of ABA reduced both disease severity and yield loss caused by F. culmorum, but neither hormone affect in vitro fungal growth. Conclusions Both IAA and ABA are involved in the P. fluorescens-mediated control of FHB disease of barley. Gene expression studies also support the hypothesis that IAA plays a role in the primed response to F. culmorum. This hypothesis was validated by the fact that pre-application of IAA reduced
Arrom, Laia; Munné-Bosch, Sergi
In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers. Copyright © 2012 Elsevier GmbH. All rights reserved.
Harbaoui, K.; Hamada, W.; Li, Y.; Vleeshouwers, V.G.A.A.; Lee, van der T.A.J.
In Tunisia, late blight caused by Phytophthora infestans is a serious threat to potato and tomato. The Mediterranean weather conditions can be conducive to infection in all seasons and the host crops, tomato and potato, are grown year round. Potato is planted and harvested in two to four overlapping