Objective  Genetic differences and mycelial morphology of imported and locally cultivated Lyophyllum decastes (Lyd) were compared.

  Methods   Sequence homology, multiple sequence alignment, and phylogenetic tree were examined and constructed based on the sequences of the fungal 18S rRNA (V4) and ITS (ITS1-ITS4) (18S rRNA-ITS) of the imported and locally cultivated Lyd strains. Mutation analysis and genetic distance determination were performed to identify the phylogenetic relationship, while mycelium growth and scanning electron microscopic images observed to differentiate the morphology of the strains.

  Results  The 18S rRNA-ITS sequence alignment between the two strains showed the imported Lyd-LR1, Lyd-LR6, Lyd-LR10, Lyd-LR15, and Lyd-LR17 to be higher on the ratio of base deletion and base substitution mutations. The ITS sequence homology between them decreased to 80.09%–89.72% with Lyd-LR1 and Lyd-LR6 being higher than Lyd-LR10, Lyd-LR15, Lyd-LR17 as well as the local Lyd-LRX and Lyd-LRY on the proportions of base mutation. The phylogenetic tree analysis indicated a distant genetic relationship between Lyd-LR1 and Lyd-LR6 and Lyd-LR10, Lyd-LR15, Lyd-LR17, Lyd-LRX, Lyd-LRY, and some Lyd or Lyophyllum (Ly) registered by NCBI. The loose and radial fusiform mycelia of Lyd-LR1 grew slowly and irregularly, whereas the pitted mycelia of Lyd-LR6 tiled with high margin thickness proliferated rapidly and polymerized considerably. The growth rates and morphology of Lyd-LR1 and Lyd-LR6 mycelia differed from those of Lyd-LR10, Lyd-LR15, Lyd-LR17, Lyd-LRX, and Lyd-LRY, which had full cylindrical mycelia and thick and fast-growing protuberant mycelia. Compared to Lyd-LR1, Lyd-LR6 exhibited more apparent changes in gene sequence base mutation location, base mutation proportion, and mycelial morphology.

  Conclusion  The gene sequence base mutation location (base substitution and base deletion), 18S rRNA-ITS sequence homology, and phylogenetic relationship of Lyd-LR6 significantly differed from those of the other imported and the locally cultivated Lyd strains. A high proportion of gene sequence base mutations induced significant changes in the growth and morphology of Lyd-LR6 mycelia indicating a potential use of it in breeding new varieties of Lyd mushrooms.