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In the present study we bioprimed seeds of six vegetable crops (tomato, brinjal, chilli, okra, ridge gourd and guar) with different spore doses of Trichoderma asperellum BHUT8 ranging from 10 2 to 10 8 spores ml −1 and the effect of biopriming was seen on seed germination and development. The most effective spore dose for enhancement in seed germination and radicle length was found to be 10 3 spores ml −1 in tomato and ridge gourd, 10 4 spores ml −1 in brinjal and okra while 10 6 spores ml −1 in chilli and guar. At the most effective spore dose, the increase in germination percentage was 5, 146.15, 112.5, 5.4, 28.13 and 0% while increase in radicle length was 73.17, 50.83, 171.6, 107.35, 247.19 and 90.79% in tomato, brinjal, chilli, okra, ridge gourd and guar, respectively, compared to their controls. Higher spore dose i . e . 10 7 –10 8 spores ml −1 and 10 6 –10 8 spores ml −1 in tomato and brinjal, respectively, reduced seed germination percentage and radicle growth compared to their controls. Biopriming with T. asperellum BHUT8 also triggered various defense like responses such as high phenylpropanoid activities and lignifications in bioprimed tomato seedlings compared to the non-bioprimed tomato seedlings demonstrating possible use of BHUT8 against phytopathogens. [ABSTRACT FROM AUTHOR]

Fusarium wilt is one of the most prevalent and damaging diseases of tomato. Among various toxins secreted by the Fusarium oxysporum f. sp. lycopersici (causal agent of Fusarium wilt of tomato), fusaric acid (FA) is suspected to be a potent pathogenicity factor in tomato wilt disease development. With this rationale the present study was carried out with physiological, biochemical and proteomic perspectives. Treatment of FA was given to the leaves of tomato directly through infiltration to show the characteristic features of Fusarium wilt of tomato. The phytotoxic effect of FA was assessed in the form of cell death in tomato leaves which was observed by increased uptake of Evans blue stain. The measurement of electrolyte leakage was used as an indicator of the extent of cell death. The influence of FA on the leaf photosynthesis of tomato plant was investigated and it was found that FA strongly reduced the photosynthetic pigment contents of tomato leaves resulting to heavy suppression of leaf photosynthesis processes, which therefore affected leaf physiology finally leading to leaf wilting and necrosis. This cell death inducer (FA) produced an enormous oxidative burst during which large quantities of reactive oxygen species (ROS) like H 2 O 2 was generated in the treated leaf tissues of tomato plants which was evident from enhancement in lipid peroxidation. To assess the involvement of proteolysis in the cell death cascade induced by FA treatment, total protease activity was measured in the leaf tissues and it was found that the total protease activity increased with the treatment and leading to cell death. Furthermore, proteomic study was used as a powerful tool to understand the alterations in cellular protein expression in response to FA exposure. Differential expression in several proteins was observed in the present study. Proteomic analyses, thus, clearly indicate that proteins belonging to different functional classes are significantly affected in the plant leaf tissues after FA exposure leading to deterioration of structure and metabolism of cells. Thus, it is concluded that FA plays an important role in fungal pathogenicity by decreasing cell viability. [ABSTRACT FROM AUTHOR]

Abstract: The study was conducted to examine efficacy of a rhizospheric microbial consortium comprising of a fluorescent Pseudomonas (PHU094), Trichoderma (THU0816) and Rhizobium (RL091) strain on activation of physiological defense responses in chickpea against biotic stress caused by the collar rot pathogen Sclerotium rolfsii. Results of individual microbes were compared with dual and triple strain mixture treatments with reduced microbial load (1/2 and 1/3rd, respectively, of individual microbial load compared to single microbe application) in the mixtures. Periodical studies revealed maximum activities of phenylalanine ammonia lyase [E.C. 4.1.3.5] and polyphenol oxidase [E.C. 1.14.18.1] and accumulation of total phenol content in chickpea in the triple microbe consortium treated plants challenged with the pathogen compared to the single microbe and dual microbial consortia. Similarly, the expression of the antioxidant enzymes superoxide dismutase [E.C.1.15.1.1] and peroxidase [E.C.1.11.1.7] was also highest in the triple microbial consortium which was correlated with lesser lipid peroxidation in chickpea under the biotic stress. Histochemical staining clearly showed maximum and uniform lignification in vascular bundles of chickpea stem sections treated with the triple microbes. The physiological responses were directly correlated with the mortality rate as least plant mortality was recorded in the triple microbe consortium treated plants. The results thus suggest an augmented elicitation of stress response in chickpea under S. rolfsii stress by the triple microbial consortium in a synergistic manner under reduced microbial load. [Copyright &y& Elsevier]