Multigene differences betweenMicrodochium nivaleandMicrodochium majus

Abstract

Microdochium nivale (Fr.) Samuels & Hallett and Microdochium majus (Wollenw.) Glynn & S.G. Edwards are sister species that cause diseases on grasses and cereals at low temperatures. The DNA sequences of RPB2 (RNA polymerase II), β-tubulin, EF-1α (elongation factor), and ITS (rDNA internal transcribed spacer) from these groups were analysed to compare the extent of differences between these species, among isolates from Europe compared with those from North America, and among isolates of M. nivale originally collected from Agrostis spp. compared with isolates from wheat (Triticum aestivum). All of the regions studied except for ITS resolved M. nivale and M. majus isolates into separate clades. The RPB2 sequences also resolved both the North American and European M. majus isolates and M. nivale isolates from either turfgrasses or wheat into separate clades. These results support the recent elevation of M. nivale and M.majus to sister species and also provide some support for the assertion that there may be host-specific differences among M. nivale, which has a wider host range than M. majus.