J Krishnamurthy, R Samiyappan*, P Vidhyasekaran*, S Nakkeeran*, E Rajeswari* ,
J A J Raja and P Balasubramanian^†

Centre for Plant Molecular Biology and *Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641 003, India

Thirty-five strains of Trichoderma viride and T. harzianum were screened for their antagonistic ability against the rice sheath blight pathogen, Rhizoctonia solani. The strains that inhibited/overgrew the phytopathogenic fungus were considered effective. Light microscopic studies showed the antagonism of the hyphae of effective Trichoderma strains towards their host hyphae. Chitinase activity of Trichoderma culture filtrates was enhanced, when colloidal chitin was used as the sole carbon source, instead of glucose. Chitinase pattern differed among the four select strains. The chitinase isoforms are induced differentially by carbon sources. The chitin affinity column fraction of Trichoderma culture filtrate inhibited, in vitro, the growth of R. solani.

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