PCR-fingerprinting of some Trichoderma isolates from two Indian type culture collections - a need for re-identification of these economically important fungi

摘要

Species in the fungal genus Trichoderma (Ascomycetes, Hypocreales) are of great economic importance as sources of enzymes, antibiotics, as plant growth promoters, xenobiotic degraders, and most importantly, as commercial biofungicides. Two species (T. longibrachiatum and T. citrinoviride) are also known to be opportunistic pathogens on immuno-suppressed patients. Until recently, Trichoderma spp. were being identified based on morphological data like cultural characteristics, structure of conidio-phores/conidia, etc.. However, subsequent molecular analysis of several strains, including some ex-type strains revealed that classification based on morphological data has been, to a great extent, erroneous resulting in re-classification of several isolates and species. For example, three Indian isolates of Trichoderma that are deposited at Microbial Type Culture Collection, Chandigarh as T. harzianum, were examined by Hermosa et al.. Two of them were found to be T. inhamatum, and one was classified asT. longibrachiatum, using molecular tools. Correct identification of Trichoderma spp. is important both from commercial point of view (as several traits are species-specific), and from the safety point of view. This is particularly important for the typecultures, as these are used by several workers and are taken as authentic samples. We therefore examined some representative isolates of this commercially important fungal genus using two PCR-based techniques (RAPD-random amplified polymorphic DNA, andrestriction analysis of the amplified ITS1-5.8S-ITS2 region of the nuclear ribosomal DNA).