Identification of potent strains of Trichoderma showing antagonism to Rhizoctonia solani in rice and isolation of partial antifungal chitinase gene

Thirty soil samples were collected from sheath blight infected rice fields of Punjab Agricultural University, Ludhiana for identification of potent strains of Trichoderma showing antagonism to Rhizoctonia solani Kuhn. Trichoderma strains were grown on PdA for 3–5 days and visually observed for characters like colony colour, colony type, growth rate, discoloration of media, number of sclerotia, parasitism of sclerotia, extent of parasitism of sclerotia, coverage of Petriplate and effectiveness. The comparisons of attributes were made with taxonomic key for the genus Trichoderma leading to tentative identification of 38 Trichoderma strains. The dual culture analysis of Trichoderma strains with R. solani led to detection of 24 antagonistic Trichoderma strains. The strain designated as S-15 was observed to be most potent and the microscopic analysis revealed R. solani to be growth inhibitor. The genomic dnA was isolated from the 24 antagonistic Trichoderma strains for isolation of chitinase gene(s). The authentication of genomic dnA was done through PCr using housekeeping actin gene specific primers, resulting in amplification of expected 137bp product in sample S-15. The internal PCR primers were designed to isolate antifungal chitinase gene from S-15. The results revealed two independent amplicons of approximately 1020bp and 771bp size on 1.5 per cent agarose gel with primer SB-14F/r and SB-35F/r, respectively corresponding to two partial chitinase gene(s). The partial chitinase genes were sequenced and authenticated through BlAST for homology with other antifungal genes.