Isolation, Characterisation and Screening of Native Microbial Isolates for Biocontrol of Fungal Pathogens of Tomato

Abstract

The native strains of Trichoderma and Rhizobacteria were isolated from rhizosphere of seven different crops from agroecosystem of peri-urban area of Lucknow, Uttar Pradesh, (India). The five isolates Trichoderma lixii TvR1, T. brevicompactum TbS2, Bacillus subtilis BS6, B. subtilis CS13 and Pseudomonas aeruginosa Tr20 displayed positive antagonistic potential against Fusarium oxysporum f. sp. lycopersici (Fol) and Alternaria solani under in vitro conditions. The biocontrol agents (BCAs) were found to produce cell wall degrading enzymes (CWDEs) including, chitinase, protease and cellulase. T. lixii TvR1 and P. aeruginosa Tr20 were found to be the most effective strains that showed significant inhibitory effect on pathogens. Dual culture, volatile metabolite and culture filtrate assay revealed percentage radial inhibition of Fol (55.31%, 54.09%; 22.24%, 10.06% and 67.85%, 51.38%) and A. solani (66.54%, 61.54%; 20.76%, 27.6% and 41.74%, 38.52%) by T. lixii TvR1 and P. aeruginosa Tr20, respectively. Antagonistic assays revealed probable involvement of mechanism of mycoparasitism and production of secondary metabolites such as antibiotics by both biocontrol agents. In addition to biocontrol activity, the BCAs displayed plant growth promoting (PGP) activities such as production of indole acetic acid (IAA), siderophores and ammonia and phosphate solubilisation.