Characterization of Indian native isolates of Trichoderma spp. and assessment of their bio-control efficiency against plant pathogens

Abstract

A study was intended to corroborate the positive relatedness of molecular and morphological characters with antagonistic ability of Trichoderma species. On the basis of morphological and cultural characteristics, the Trichoderma isolates were identified as T. virens (11 isolates), T. asperellum (15), T. harzianum (14) and T. longibrachiatum (32). This result was in concordance with the result obtained from the DNA sequence data analysis of internal transcribed spacer 1 and 2 region (ITS1 and ITS2) and the elongation factor 1-alpha gene (tef1). The phylogenetic analyses of the above two marker loci sequences were done. Trichoderma isolates were not fairly separated by ITS 1 and 2 regions analysis whereas these were clearly separated with tef1 sequences analysis into different clusters. Comparative sequence analyses suggest that tef1 is a better marker to distinguish Trichoderma species because of greater transition/transversion ratio (1.32) and evolutionary divergence (1.965). T. virens (Vn) and T. harzianum (Th) were assessed for their mycoparasitic effect on soil borne plant pathogens, Rhizoctonia solani, Pythium aphanidermatum, Fusarium udum, F. solani, Sclerotium rolfsii and Macrophomina phaseolina. The percent inhibitory effect among T. harzianum isolates was between 70 to 90% and T. virens isolates ranged from 50 to 80%. However, Vn09 and Th-12 were distinguishable in exhibiting higher degree of antagonism.

Key words: Biocontrol, ITS, tef1, Trichoderma.