Environmental adaptation and intraspecific differentiation of cold-adapted basidiomycetous fungi

雪霉是牧草作物、冬季谷物和针叶树苗的嗜冷性或嗜冷性真菌病原体。这些真菌可以在积雪覆盖的低温下生长并攻击休眠的植物。在本研究中，我们调查了属于不同类群的雪霉的生物多样性和生理生化特性。耐寒性是与雪霉地理分布有关的重要因素之一，因为雪霉在雪盖下发育菌丝，并在低温下产生活性较高的胞内酶和胞外酶，以便生长和感染。担子菌类雪霉产生胞外抗冻蛋白。它们的生理意义是保持细胞外环境不冻结。北方嗜冷子囊菌在冷冻条件下菌丝生长正常，在最适生长温度下生长速度快于未冷冻条件下的菌丝生长速度。这种真菌不产生胞外抗冻蛋白，但渗透胁迫耐受性使该真菌能够在零度以下的温度下生长。综上所述，不同的雪霉类群在雪盖下的适应策略不同。

Snow molds are psychrophilic or psychrotrophic fungal pathogens of forage crops, winter cereals, and conifer seedlings. These fungi can grow and attack dormant plants at low temperatures under snow cover. In this study, we surveyed the biodiversity and physiological and biochemical characteristics of snow molds that belong to various taxa. Cold tolerance is one of the important factors related to their geographic distribution, because snow molds develop mycelia under snow cover and because they should produce intra- and extracellular enzymes active at low temperatures for growth and infection. Basidiomycetous snow molds produce extracellular antifreeze proteins. Their physiological significance is to keep the extracellular environment unfrozen. The psychrophilic ascomycete Sclerotia borealis shows normal mycelial growth under frozen conditions, which is faster than that on unfrozen media at optimal growth temperature. This fungus does not produce extracellular antifreeze proteins, but osmotic stress tolerance enables the fungus to grow at subzero temperatures. In conclusion, different taxa of snow molds have different strategies to adapt under snow cover.