Biogeography and phenotypic variation in Trichoderma sect Longibrachiatum and associated Hypocrea species

Abstract

Random amplification of polymorphic DNA (RAPD), using both fingerprinting (M13, [GTG](5), [GACA](4)) and random [V5] primers; has been used to analyse 145 isolates characteristic of Trichoderma sect. Longibrachiatum and Hypocrea species with anamorphs referable to that section, and to identify strains with named species of sect. Langibrachiatum. To this end, ex-type strains of T. longibrachiatum, T. pseudokoningii, T. citrinoviride, T. parceramosum and T., resei were analysed, and the similarity coefficients of RAPD characters used as a criterion for the alignment of strains to individual species. The ex-type strains of T. saturnisporum and T. ghanense exhibited the same interspecific similarity index as the other ex-type strains of Trichoderma sect. Longibrachiatum, and clustered well within it and were therefore included into this section. 103 isolates were identified as members of Trichoderma sect. Longibrachiatum and further investigated. Most of the anamorphic isolates could be aligned with T. citrinaviride or T. longibrachiatum, whereas only a few strains of T. saturnisporum and T. parceramosum were found. No naturally occurring anamorphs with homology to the ex-type strains of T. reesei and T. pseudokoningii were found. While T. longibrachiatum and T. citrinoviride overlapped through much of their geographic ranges, the former was, present in Africa and India but not in southeast Asia, while the reverse was true of the latter. The African strains of T. longibrachiatum were equally distant from the ex-type strains of T. longibrachiatum, T. parceramosum and T. saturnisporum. The type strain of T. ghanense was identified as belonging to this group. T. pseudokoningii, the anamorph of Hypocrea schweinilzii, was found exclusively in eastern Australia and New Zealand. Attempts to identify potential teleomorphs of the other anamorphs revealed another subgroup of H. schweinilzii, occurring in temperate climates in Europe and U.S.A., as homologous to T. citrinoviride. No Hypocrea strains could be identified as teleomorphs of T. longibrachiatum, T. parceramosum or T. saturnisporum.