Antipathy of Trichoderma against Sclerotium rolfsii Sacc.: Evaluation of Cell Wall-Degrading Enzymatic Activities and Molecular Diversity Analysis of Antagonists

Abstract

The fungus <i>Trichoderma</i> is a teleomorph of the <i>Hypocrea</i> genus and associated with biological control of plant diseases. The microscopic, biochemical, and molecular characterization of <i>Trichoderma </i>was carried out and evaluated for in vitro antagonistic activity against the fungal pathogen <i>Sclerotium rolfsii</i> causing stem rot disease in groundnut. In total, 11 isolates of <i>Trichoderma</i> were examined for antagonism at 6 and 12 days after inoculation (DAI). Out of 11, <i>T. virens </i>NBAII Tvs12 evidenced the highest (87.91%) growth inhibition of the test pathogen followed by <i>T. koningii</i> MTCC 796 (67.03%), <i>T. viride </i>NBAII Tv23 (63.74%), and <i>T. harzianum </i>NBAII Th1 (60.44%). Strong mycoparasitism was observed in the best antagonist Tvs12 strain during 6-12 DAI. The specific activity of cell wall-degrading enzymes - chitinase and β-1,3-glucanase - was positively correlated with growth inhibition of the test pathogen. In total, 18 simple sequence repeat (SSR) polymorphisms were reported to amplify 202 alleles across 11 <i>Trichoderma </i>isolates. The average polymorphism information content for SSR markers was found to be 0.80. The best antagonist Tvs 12 was identified with 7 unique SSR alleles amplified by 5 SSR markers. Clustering patterns of 11 <i>Trichoderma </i>strains showed the best antagonist <i>T. virens</i> NBAII Tvs 12 outgrouped with a minimum 3% similarity from the rest of <i>Trichoderma.</i>