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In the present investigative study, fifty Trichoderma spp. (Persoon) were isolated from the rhizosphere of various crop plants. Their potential, as an antagonist was assessed against S. sclerotiorum (Lib.) de Bary , causing stem rot of carnation ( Dianthus caryophyllus L.). T. asperellum (NVTA2) was superior in inhibiting the growth and development of stem rot pathogen up to 53.7 per cent in vitro . Seven Trichoderma species with greatest antagonistic potential were identified up to species level through molecular characterization. They were identified as T. asperellum (NVTA1, NVTA2), T. harzianum (NVTH1, NVTH2), T. citrinoviride (NVTC1, NVTC2), and T. erinaceum (NVTE1). Effective strains were screened for the presence of cellobiohydrolase ( cbh1 ) and endochitinase ( ech42 ) genes through PCR. Among the seven strains, T. asperellum (NVTA2) alone had both genes. Crude metabolite extracted from T. asperellum (NVTA2), effectively inhibited the mycelial growth of S. sclerotiorum up to 374.4 mm 2 . GC/MS profiling of crude extract revealed the presence of antifungal compounds including aliphatic hydrocarbons, terpenes and fatty acids. Root dipping and soil application of talc formulations of the seven Trichoderma spp. revealed that T. asperellum (NVTA2) effectively suppressed disease incidence up to 11.8 (PDI-Percent Disease Incidence) compared to the control (37.9 PDI), resulting in approximately 69% reduction. More over NVTA2 also promoted plant growth that resulted in increase in shoot numbers (6.60/plant), stalk length (72.7 cm) and flower yield (205.9 numbers/m 2 ), which were comparatively greater than control. [ABSTRACT FROM AUTHOR]

The perception of pathogen-associated molecular patterns (PAMPs) by immune receptors launches defence mechanisms referred to as PAMP-triggered immunity (PTI). Successful pathogens must suppress PTI pathways via the action of effectors to efficiently colonize their hosts. So far, plant PTI has been reported to be active against most classes of pathogens, except viruses, although this defence layer has been hypothesized recently as an active part of antiviral immunity which needs to be suppressed by viruses for infection success. Here, we report that Arabidopsis PTI genes are regulated upon infection by viruses and contribute to plant resistance to Plum pox virus (PPV). Our experiments further show that PPV suppresses two early PTI responses, the oxidative burst and marker gene expression, during Arabidopsis infection. In planta expression of PPV capsid protein (CP) was found to strongly impair these responses in Nicotiana benthamiana and Arabidopsis, revealing its PTI suppressor activity. In summary, we provide the first clear evidence that plant viruses acquired the ability to suppress PTI mechanisms via the action of effectors, highlighting a novel strategy employed by viruses to escape plant defences. [ABSTRACT FROM AUTHOR]

Apple scab (Venturia inaequalis (Cke) Wint) is the main disease of apple trees not only in the world but also in Turkey. The disease can cause severe yield losses in all Turkish apple orchards. Genetic diversity and relatedness of apple scab (Venturia inaequalis (Cke) Wint) isolates collected from Turkey and Europe were investigated in this study through molecular markers. RAPD, ISSR, SSR and SRAP markers were used in the molecular studies. Results obtained by marker system revealed that isolates were quite separated from each other and it is appeared to exist a variation between them. Genetic relatedness between the isolates are very close to each other, and difference among the groups is not significant due to host specificity and geographical location. The groups are consisted of more number of isolates when SSR and SRAP markers are used compared with ISSR and RAPD markers. Using SSR and SRAP markers are preferable to provide more informative outcomes because of ease of use, repeatability and specificity. [ABSTRACT FROM AUTHOR]

Investigating the origin and dispersal pathways is instrumental to mitigate threats and economic and environmental consequences of invasive crop pathogens. In the case of Puccinia striiformis causing yellow rust on wheat, a number of economically important invasions have been reported, e.g., the spreading of two aggressive and high temperature adapted strains to three continents since 2000. The combination of sequence-characterized amplified region ( SCAR) markers, which were developed from two specific AFLP fragments, differentiated the two invasive strains, PstS1 and PstS2 from all other P. striiformis strains investigated at a worldwide level. The application of the SCAR markers on 566 isolates showed that PstS1 was present in East Africa in the early 1980s and then detected in the Americas in 2000 and in Australia in 2002. PstS2 which evolved from PstS1 became widespread in the Middle East and Central Asia. In 2000, PstS2 was detected in Europe, where it never became prevalent. Additional SSR genotyping and virulence phenotyping revealed 10 and six variants, respectively, within PstS1 and PstS2, demonstrating the evolutionary potential of the pathogen. Overall, the results suggested East Africa as the most plausible origin of the two invasive strains. The SCAR markers developed in the present study provide a rapid, inexpensive, and efficient tool to track the distribution of P. striiformis invasive strains, PstS1 and PstS2. [ABSTRACT FROM AUTHOR]

Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. [ABSTRACT FROM AUTHOR]

This study used both microscopic and biochemical analyses to investigate the possible defense responses induced by acibenzolar-S-methyl (ASM) and potassium phosphite (Phi) in mango plants inoculated with Ceratocystis fimbriata. Disease development was evaluated in the stems of inoculated mango plants and these were examined using fluorescence and light microscopy. High-performance liquid chromatography (HPLC) was used to quantify secondary metabolites in the stem sections. Spraying the plants with ASM and Phi reduced internal necrosis and disease development. The ASM and Phi induced many microscopic defense responses in the stem tissues against C. fimbriata infection. HPLC analysis revealed that the concentrations of two alkaloids (theobromine and 7-methylxanthine) and 10 phenolic compounds (catechin, epicatechin, epigallocatechin, gallic acid, myricetin. pcoumaric acid, p-hydroxybenzoic acid, phloridzin, sinapinic acid, and salicylhydroxamic acid) were higher in the stem tissues of plants sprayed with ASM or Phi than in inoculated control treatment. The concentrations of phenolic compounds were higher in the stem tissues of inoculated plants than in noninoculated plants, while the inverse was observed for alkaloids. Higher concentrations of secondary metabolites in the stem tissues were detected in the early stages of fungal infection, especially in plants treated with inducers. Taken together, the results from the present study clearly support the concept that the phenylpropanoid pathway in the stem tissues of mango plants infected by C. fimbriata can be induced by ASM and Phi. [ABSTRACT FROM AUTHOR]

The article presents an introduction to the issue on the theme of genomics research on rust fungi plant pathogens, including topics such as transcriptome analysis, effector proteins, and genetic aspects of fungal virulence.