Hypsizygus marmoreus is one of the most important edible fungi in Basidiomycete division and includes white and gray strains.However,very limited knowledge is known about the genomic structures and the genetic basis for the white/gray diversity of this mushroom.Here,we report the near-complete high-quality H.marmoreus genome at the chromosomal level.Comparative genomics analysis indicates that chro-mosome structures were relatively conserved,and variations in collinearity and chromosome number were mainly attributed by chromosome split/fusion events in Aragicales,whereas the fungi genome experienced many genomic chromosome fracture,fusion,and genomic replication events after the split of Aragicales from Basidiomycetes.Resequencing of 57 strains allows us to classify the population into four major groups and associate genetic variations with morphological features,indicating that white strains were not origi-nated independently.We further generated genetic populations and identified a cytochrome P450 as the candidate causal gene for the melanogenesis in H.marmoreus based on bulked segregant analysis (BSA)and comparative transcriptome analysis.The high-quality H.marmoreus genome and diversity data compiled in this study provide new knowledge and resources for the molecular breeding of H.marmoreus as well as the evolution of Basidiomycete.