Comparative Genomics Reveals Species-Specific Genes and Symbiotic Adaptations in .

, a highly valued ectomycorrhizal fungus, requires a symbiotic relationship with pine trees for growth, complicating its cultivation. This study presents a comprehensive comparative genomic analysis of species, with a focus on . Genomic data from 19 assemblies representing 13 species were analyzed to identify genus-, species-, and strain-specific genes, revealing significant evolutionary adaptations. Notably, exhibits a higher proportion of repetitive elements compared to other species, with retrotransposons like LTR Gypsy dominating its genome. Phylogenomic analyses showed that forms a monophyletic group closely related to . Gene family expansion and contraction analyses highlighted the unique evolutionary pressures on , particularly the loss of tryptophan-related metabolic pathways and the gain of genes related to iron ion homeostasis, which may be crucial for its adaptation to nutrient-limited environments. Additionally, the reduction in secreted proteins and carbohydrate-active enzymes reflects the host-dependent lifestyle of and related species. These findings enhance our understanding of the genetic and evolutionary mechanisms underlying the complex symbiotic relationships of , offering potential avenues for optimizing its cultivation and commercial value.