Low Genetic Diversity and Broadly Distributed Haplotype Lineages Characterize Microdochium nivale and Typhula spp. Infecting Turfgrass in Norway and the Uni

Snow mold diseases of amenity turfgrass occur in temperate climates around the world and are caused by taxonomically diverse fungal species that infect hosts during periods of low temperature and high moisture. This study used multi-locus DNA sequencing (ITS, TEF, and RPB2) to explore phylogenetic relationships and genotypic variation among 50 isolates of Microdochium nivale, Typhula incarnata, and Typhula ishikariensis collected from Norway and selected regions around the United States. Phylogenetic analyses revealed consistent and well-supported topologies for each species among the isolates examined. The lack of geographic clustering within species suggests the possibility of gene flow or widespread dispersal among populations. Furthermore, low nucleotide diversity and a high proportion of monomorphic sites indicated limited genotypic variation, particularly within M. nivale and T. incarnata, both of which were characterized by a single dominant, widespread haplotype. These patterns preliminary reflect the persistence of successful lineages and their adaptation to managed turfgrass environments. While this genetic uniformity within this study set may point toward consistent responses to management strategies, the dominance of specific lineages warrants further investigation into the rapid spread of adaptive traits.