Telomere-to-Telomere Genome Assembly of Coprinellus disseminatus and Genomic Insights into Its Symbiotic Germination of Cremastra appendiculata Seeds

Cremastra appendiculata is a medicinally important orchid whose seed germination depends on fungal symbionts. Here, we present the first telomere-to-telomere (T2T) genome assembly of the orchid mycorrhizal fungus Coprinellus disseminatus, comprising 15 gapless chromosomes (54.41 Mb) with 98.80% BUSCO completeness. Symbiotic germination assays demonstrated that C. disseminatus significantly outperformed its congeners C. domesticus and C. radians in protocorm biomass. Comparative genomic analyses revealed highly conserved carbohydrate-active enzyme (CAZyme) repertoires among the three species, ruling out CAZyme divergence as the primary driver of differential symbiotic performance. CAFE analysis showed that since its divergence approximately 117.8 million years ago, C. disseminatus underwent substantial gene family expansions enriched in proteasome, endocytosis, adherens junction, and tight junction pathways, suggesting that lineage-specific expansion of these functional modules may have contributed to its superior symbiotic capacity for orchid seed germination. These findings require further experimental validation through transcriptomic and functional genomic approaches.