Molecular characterization of Trichoderma taxa causing green mould disease in edible mushrooms

Abstract

Trichoderma taxa associated with green mould disorder of edible mushrooms were isolated from both fruit bodies and substrates of Agaricus bisporus, A. bitorquis, Calocybe indica, Ganoderma lucidum, Lentinula edodes, Pleurotus sajor-caju, and Volvariella volvacea. Emerged fruiting bodies in the affected portion of the substrate were badly spotted, brownish in colour and reduced in both growth rate and yield performance. Microscopic examination of cultures revealed significant differences in fungal morphology, but were difficult to designate as Trichoderma species. The nucleotide sequence comparisons of 5.8S rRNA gene using BLAST network facilitated molecular identification and genetic cataloguing of 18 Trichoderma isolates into two taxa, namely T. harzianum and T. virens. RAPD primers exhibited both inter- and intra-specific variations among the test isolates and separated them into eight distinct phylogenetic sub-clades. The present study underlines the potential threat of green mould disorders in cultivated mushrooms and validates existence of significant intraspecific diversity in isolates of both T. harzianum and T. virens.