Isolates of Microdochium nivale and M. majus Differentiated by Pathogenicity on Perennial Ryegrass (Lolium perenne L.) and in vitro Growth at Low Temperature

• Published in: Journal of phytopathology Vol. 154; no. 5; pp. 267 - 274
• Main Authors: Hofgaard, I.S, Wanner, L.A, Hageskal, G, Henriksen, B, Klemsdal, S.S, Tronsmo, A.M
• Format: Journal Article
• Language: English
• Published: Berlin, Germany Berlin, Germany : Blackwell Verlag GmbH 01.05.2006; Blackwell Verlag GmbH; Blackwell
• Subjects: ambient temperature; Biological and medical sciences; cold; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; Fungal plant pathogens; lawns and turf; Lolium perenne; microbial growth; Microdochium; Microdochium majus; Microdochium nivale; Monographella nivalis; pathogen identification; pathogenicity; Phytopathology. Animal pests. Plant and forest protection; pink snow mould; plant pathogenic fungi; strain differences; strains; turf grasses; virulence; α-galactosidase; β-glucosidase; Monocotyledones; Plant pathology; Temperature; Microbiology; Growth rate; Cell wall; Fungi; Gramineae; Dicotyledones; Angiospermae; Fungi Imperfecti; Solanaceae; Lolium perenne; Thallophyta; Microdochium nivale; Enzyme; Solanum tuberosum; Method; pink snow mould; Pathogenicity; Resistance; β-Glucosidase; α-Galactosidase; Glycosidases; Hydrolases; Isolate; Herbaceous plant; Spermatophyta; Tuber plant; O-Glycosidases
• ISSN: 0931-1785; 1439-0434
• DOI: 10.1111/j.1439-0434.2006.01092.x

Pink snow mould is a serious disease on grasses and winter cereals in cold and temperate zones during winter. To better understand the basis for the variation in pathogenicity between different isolates of Microdochium nivale and M. majus and to simplify selection of highly pathogenic isolates to use when screening for resistance to pink snow mould in perennial ryegrass, we sought traits correlated with pathogenicity. Isolates of M. nivale were more pathogenic on perennial ryegrass than isolates of M. majus, as measured by survival and regrowth of perennial ryegrass after infection and incubation under simulated snow cover. Pathogenicity as measured by relative regrowth was highly correlated with fungal growth rate on potato dextrose agar (PDA) at 2°C. Measuring fungal growth on PDA therefore seems to be a relatively simple method of screening for potentially highly pathogenic isolates. In a study of a limited number of isolates, highly pathogenic isolates showed an earlier increase and a higher total specific activity of [beta]-glucosidase, a cell wall-degrading enzyme, compared with less pathogenic isolates. None of the M. majus isolates was highly pathogenic on perennial ryegrass. Our results indicate biological differences between M. nivale and M. majus and thus strengthen the recently published sequence-based evidence for the elevation of these former varieties to species status.