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Blight Pathogen (blight + pathogen)
Selected AbstractsMicrosatellite markers for the red band needle blight pathogen, Dothistroma septosporumMOLECULAR ECOLOGY RESOURCES, Issue 5 2008I BARNES Abstract Twelve microsatellite markers were developed for population analyses of the fungal pathogen, Dothistroma septosporum. Intersimple sequence repeat polymerase chain reaction (ISSR-PCR) and an enrichment protocol (fast isolation by amplified fragment length polymorphism of sequences containing repeats [FIASCO]) were both used to identify 28 unique microsatellite regions in the genome. From 22 primer pairs designed, 12 were polymorphic. These markers, screened on two populations representing 42 isolates, produced 40 alleles across all loci with an allelic diversity of 0.09,0.76 per locus. Cross-species amplification showed variable success with Dothistroma rhabdoclinis and Mycosphaerella dearnessi and some sequence variation within isolates of Dothistroma pini. These markers will be used to further study the population structure and diversity of D. septosporum. [source] Promoter elements of rice susceptibility genes are bound and activated by specific TAL effectors from the bacterial blight pathogen, Xanthomonas oryzae pv. oryzaeNEW PHYTOLOGIST, Issue 4 2010Patrick Römer Summary ,Plant pathogenic bacteria of the genus Xanthomonas inject transcription activator-like effector (TALe) proteins that bind to and activate host promoters, thereby promoting disease or inducing plant defense. TALes bind to corresponding UPT (up-regulated by TALe) promoter boxes via tandemly arranged 34/35-amino acid repeats. Recent studies uncovered the TALe code in which two amino acid residues of each repeat define specific pairing to UPT boxes. ,Here we employed the TALe code to predict potential UPT boxes in TALe-induced host promoters and analyzed these via ,-glucuronidase (GUS) reporter and electrophoretic mobility shift assays (EMSA). ,We demonstrate that the Xa13, OsTFX1 and Os11N3 promoters from rice are induced directly by the Xanthomonas oryzae pv. oryzae TALes PthXo1, PthXo6 and AvrXa7, respectively. We identified and functionally validated a UPT box in the corresponding rice target promoter for each TALe and show that box mutations suppress TALe-mediated promoter activation. Finally, EMSA demonstrate that code-predicted UPT boxes interact specifically with corresponding TALes. ,Our findings show that variations in the UPT boxes of different rice accessions correlate with susceptibility or resistance of these accessions to the bacterial blight pathogen. [source] PGPR and entomopathogenic fungus bioformulation for the synchronous management of leaffolder pest and sheath blight disease of ricePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 5 2010Loganathan Karthiba Abstract BACKGROUND: The biological control of plant pests and diseases using a single organism has been reported to give inconsistent and poor performance. To improve the efficacy, bioformulations were developed possessing mixtures of bioagents. RESULTS: Bioformulations combining Pseudomonas fluorescens Migula strains Pf1 and AH1 and Beauveria bassiana (Balsamo) Vuill. isolate B2 were developed and tested for their efficacy against leaffolder pest and sheath blight disease on rice under glasshouse and field conditions. The combination of Pf1, AH1 and B2 effectively reduced the incidence of leaffolder insect and sheath blight disease on rice compared with other treatments. An in vitro assay of leaffolder preference to rice leaf tissues treated with Pf1 + AH1 + B2 biformulation showed variation from normal growth and development of leaffolder larvae. Plants treated with the Pf1 + AH1 + B2 combination showed a greater accumulation of enzymes, lipoxygenase and chitinase activity against leaffolder insect compared with other treatments. Similarly, the plants showed a higher accumulation of defence enzymes, peroxidase and polyphenol oxidase activity against sheath blight pathogen in Pf1 + AH1 + B2 treatment compared with the untreated control. The bioformulation mixture attracted the natural enemy population of leaffolder under field conditions. In addition, a significant increase in rice grain yield was observed in Pf1 + AH1 + B2 treatment compared with the untreated control. CONCLUSION: The combination of P. fluorescens strains and B. bassiana isolate effectively reduced the incidence of leaffolder insect and sheath blight disease on rice plants and showed the possibility of controlling both pest and disease using a single bioformulation. Copyright © 2010 Society of Chemical Industry [source] Phytophthora infestans: populations, pathogenicity and phenylamides,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 9 2002Richard C Shattock Abstract Isolates of Phytophthora infestans (Mont) de Bary (the potato and tomato late blight pathogen) resistant to phenylamides appeared in Europe and North America in the late 1970s and early 1990s respectively. Concurrent, but coincidentally, with both these events there were radical structural shifts in the pathogen populations as immigrant genotypes from Mexico displaced the indigenous populations. Both A1 and A2 mating type isolates are now present in blighted crops, permitting alternative inoculum via germinating sexually produced oospores to influence dynamics of late blight populations. Studies of inheritance of ploidy, host-specific pathogenicity, mating type and resistance to antibiotics and phenylamide fungicides have provided insight into mechanisms of variation in this potent pathogen. © 2002 Society of Chemical Industry [source] Linkage and quantitative trait locus mapping of foliage late blight resistance in the wild species Solanum verneiPLANT BREEDING, Issue 3 2006K. K. Sørensen Abstract The global cultivation of potato (Solanum tuberosum) is threatened by epidemics caused by new variants of the late blight pathogen, Phytophthora infestans. New sources of durable late blight resistance are urgently needed and these may be found in wild Solanum species. The diploid wild species, S. vernei, has not previously been subjected to mapping of quantitative trait loci (QTLs) for late blight resistance. Two populations designated HGIHJS and HGG, originating from a cross between a clone of S. vernei and two different S. tuberosum clones were evaluated in field trials for late blight infestation. The relative area under the disease progress curve (RAUDPC) was estimated and used for QTL mapping. A linkage map of S. vernei, comprising 11 linkage groups, nine of which could be assigned to chromosomes, was constructed. Results indicated that the resistance in S. vernei was quantitatively inherited. Significant QTLs for late blight resistance were identified on chromosomes VIII (HGG), VI and IX (HGIHJS). In addition, potential QTLs were detected on chromosomes VII (HGIHJS) and IX (HGG). A putative and a significant QTL for tuber yield were found on chromosomes VI and VII in HGG, but no linkage between yield and resistance was indicated. The QTL for late blight resistance, which mapped to chromosome IX, could be useful for late blight resistance breeding as it was located close to the microsatellite marker STM1051 in both populations. [source] Bacterial leaf blight of strawberry (Fragaria (x) ananassa) caused by a pathovar of Xanthomonas arboricola, not similar to Xanthomonas fragariae Kennedy & King.PLANT PATHOLOGY, Issue 6 2001Description of the causal organism as Xanthomonas arboricola pv. fragariae (pv. nov., comb. nov.) A new bacterial disease of strawberry is described. This disease, called bacterial leaf blight of strawberry, is characterized by dry, brown necrotic leaf spots and large brown V-shaped lesions along the leaf margin, midrib and major veins. Symptoms are different from angular leaf spot of strawberry caused by the bacterium Xanthomonas fragariae. Strains of the bacterial leaf blight pathogen were characterized in a polyphasic approach by biochemical tests, fatty acid analysis, protein electrophoresis, serology, PCR, pigment analysis, ice-nucleation activity, AFLP analysis, DNA:DNA hybridization, pathogenicity and host range tests, and compared with a number of reference strains of X. fragariae and other Xanthomonas species. Bacterial leaf blight strains formed a homogeneous group in all tests, completely different from X. fragariae. They were the only strains causing leaf blight of strawberry upon artificial inoculation into strawberry. Fatty acid and protein electrophoretic analysis showed that the strains belong to the phenon X. campestris (sensu latu, including pathovars now classified as belonging to X. arboricola). AFLP analysis and DNA:DNA hybridization further clarified their taxonomic position as belonging to X. arboricola. The name X. arboricola pv. fragariae is proposed for the bacterium causing leaf blight of strawberry with strain PD2780 (LMG 19145) as pathovar type strain. Criteria for routine identification are given and the taxonomic status is discussed. [source] PCR primers for identification of Sirococcus conigenus and S. tsugae, and detection of S. conigenus from symptomatic and asymptomatic red pine shootsFOREST PATHOLOGY, Issue 3 2008D. R. Smith Summary Regions of diversity in the internal transcribed spacer (ITS) sequences of Sirococcus species were exploited to design primer pairs used in a PCR-based method for the identification of the conifer shoot blight pathogen Sirococcus conigenus and the closely related fungus Sirococcus tsugae. The specificity of each primer pair for the respective fungus, detection limits and utility for detection from host material were confirmed. The S. conigenus primers were then used to detect this pathogen in tissues of symptomatic or apparently healthy red pine shoots collected at six locations in Wisconsin and Michigan and results compared with those obtained using a cultural assay. For needles, bark and wood of symptomatic shoots, the mean frequencies of detection of S. conigenus using the PCR-based methods were consistent (,7.5 out of 10) and always greater than for the cultural assay. Detection from symptomatic shoots using the cultural assay was more frequent from needles than from bark or wood. Both the PCR-based method and the cultural assay detected S. conigenus in similar frequencies from asymptomatic shoots, although less frequently than from symptomatic shoots. The efficiency of the PCR-based method and its utility for direct testing of host material should make it particularly useful in areas where multiple shoot blight pathogens are found. [source] Sympatric ascochyta complex of wild Cicer judaicum and domesticated chickpeaPLANT PATHOLOGY, Issue 3 2007O. Frenkel The aim of this study was to isolate, identify and characterize ascochyta blight pathogens from Cicer judaicum, a wild annual Cicer species which grows in Israel and other Mediterranean countries in sympatric distribution with legume crops, and determine their virulence and aggressiveness to other wild and domesticated legumes. Native C. judaicum plants exhibited symptoms resembling ascochyta diseases of grain legume crops. Two distinct pathogens were isolated and identified as Phoma pinodella and Didymella rabiei using morphological and molecular tools; their infectivity was verified using Koch's postulates. The virulence of these pathogens was examined on 13 legume species, of which P. pinodella was virulent to Pisum sativum, P. fulvum, C. judaicum, C. arietinum, C. reticulatum, C. pinnatifidum and C. bijugum. Didymella rabiei infected all these Cicer species, but not the other legume species tested. Aggressiveness of the pathogens was tested on wild and domesticated chickpea and pea. Didymella rabiei isolated from C. judaicum had significantly higher (P < 0·001) aggressiveness than P. pinodella from C. judaicum on both wild and domesticated chickpea. Disease severity on the former species ranged from 62·5% to 70% and on the latter from 41% to 56%. Phoma pinodella isolates from C. judaicum were more aggressive on C. arietinum and P. sativum than on C. judaicum and P. fulvum. Results of the current study suggest that C. judaicum may serve as an alternative host to ascochyta pathogens that endanger chickpea and possibly other crops and wild species growing in close proximity. [source] | ||||||||||