Molecular diversity and fingerprints of Trichoderma associated with antagonistic potentials against Sclerotium rolfsii Sacc.

Abstract

Antagonistic potentials of Trichoderma isolates were evaluated against the phytopathogen Sclerotium rolfsii causing stem rot in groundnut. The in vitro growth inhibition of test pathogen on potato dextrose agar medium was observed maximum by antagonist T. virens NBAII Tvs 12 followed by T. koningii MTCC 796 at 6 days after inoculation (DAI). The most effective antagonists T. virens NBAII Tvs 12 and T. koningii MTCC 796 exhibited different patterns of growth inhibition of test pathogen. The Tvs 12 isolate overgrew S. rolfsii by degrading mycelia through mycoparasitism during 6–12 DAI. Isolate MTCC 796 inhibited the growth of the pathogen by forming an inhibition zone (antibiosis). The biogenesis (formation) of sclerotia of S. rolfsii was elevated during weak antagonism and diminished in interactions with strong antagonists. Trichoderma antagonists were examined for molecular fingerprints and diversity using 23 ISSR primers which amplified 296 amplicons. Among them, 23 showed a unique polymorphism. Jaccard’s similarity coefficient ranged from 0.14 to 0.71, and clustering pattern exhibited minimum 22 % similarity between the mycoparasitic best antagonist Tvs12 and other isolates with antagonistic activity within Bi(a) cluster. The molecular fingerprints UBC-808(1221) and UBC-827(2123) were specific for Tvs 12 strain; and ISSR-5(1956) and UBC-812(1689) were specific for MTTC 796.