Molecular identification of Trichoderma species from Russia, Siberia and the Himalaya

About 35 Trichoderma species are currently recognised on the basis of morph ological and molecular characters. Besides the role of a few of these speci es in biotechnology, several seem to play prominent roles in soil ecosystem s. With a goal of investigating global biodiversity in Trichoderma, we repo rt on the occurrence of Trichoderma? spp. in Russia (Moscow and Ural areas) , Siberia (Krasnoyarsk area) and the Himalayan mountains - areas from which no Trichoderma isolates are so far available. The ITS I and 2 sequence of the rDNA cluster of the 75 isolates obtained was compared with that of ex-t ype strains and taxonomically established isolates of Trichoderma. Thirty-n ine isolates were positively identified as T. atroviride, T. virens, T. ham atum, T. asperellum, T. koningii and T. oblongisporum. A further 26 isolate s yielded six closely related ITS1/2 sequence types, which are highly simil ar yet different from the ex-(neo)type strains of T. harzianum and T. inham atum. Some of these genotypes (i.e. I and 2a) occurred only in Russia/Siber ia, whereas others (2b, 3, 4 and 5) were found only in the Himalayas. RAPD analysis was consistent with these genotypes, and revealed genetic homogene ity even between strains from widely separated areas. Parsimony analysis pl aced these five genotypes, together with T. harzianum, T. inhamatum and the mushroom-aggressive T. harzianum 'biotype 2' in a large, unresolved 'harzi anum' clade. Ten isolates were not safely alignable within known species, a nd five of them may be undescribed taxa: one isolate from 2700 in elevation in the Himalayas, which clustered in parsimony analysis at a basal positio n in section Longibrachiatum; and four isolates, displaying two closely rel ated sequence types, forming a separate clade with T. stromaticum. The five remaining isolates also exhibited three unique ITS1 and 2 sequence pattern s, hut parsimony analysis placed them into the unresolved 'harzianum' clade , and their relationship to T. harzianum is thus unclear. The study shows t hat molecular screening of uninvestigated geographic areas can lead to the identification of isolates with new ITS1 and ITS2 sequence patterns, some o f which may be new taxa. It also reveals that T. harzianum is at present th e genetically most diverse member of the genus.