Coprinellus comprises mushroom-forming saprotrophic fungi that colonize decomposing plant-derived substrates, yet chromosome-complete genomic resources for this genus remain limited. To resolve chromosome architecture and lineage-specific evolution in this fungal group, we generated chromosome-complete assemblies of Coprinellus xanthothrix and C. saccharinus by integrating Oxford Nanopore Technologies (ONT) long reads, DNA nanoball sequencing (DNBSEQ) short reads, Hi-C, and RNA-seq data. Each genome comprised 13 gapless chromosomes with all 26 telomeres recovered; assembly sizes were 46.92 and 54.81 Mb, with BUSCO completeness of 99.20% and 99.10%, respectively. The larger C. saccharinus genome was primarily associated with greater retroelement content, whereas functional annotation profiles and CAZyme repertoires were broadly comparable between species. Phylogenomic analyses grouped C. xanthothrix with C. radians and C. saccharinus with C. micaceus, with estimated divergence times of 54.4 and 32.8 Ma, respectively. Both divergence events occurred within the Paleogene. Gene family analyses identified lineage-specific expansions enriched in nucleotide metabolism, DNA replication and repair, glutathione metabolism, redox regulation, endocytosis, cytoskeletal organization, and cell-cycle processes. Synteny and Ks analyses further revealed chromosome-level rearrangements and lineage-specific small-scale duplication but no strong evidence of recent whole-genome duplication. Together, the temporal placement of these divergences and the associated genomic patterns raise a testable hypothesis that long-term climatic and vegetation reorganization, together with changes in plant-derived substrates and microhabitats, may have contributed to lineage establishment and ecological differentiation. However, because direct paleoecological evidence and functional validation are currently lacking, this proposed relationship should not be interpreted as causal. These chromosome-complete assemblies provide important resources for comparative genomics in Coprinellus and future experimental studies of saprotrophic adaptation.

Tremella sanguinea is a morphologically distinctive gelatinous mycoparasite of Stereum within Tremellales whose generic placement has remained unresolved for lack of high-quality genomic resources. We combined Oxford Nanopore long-read sequencing, short-read whole-genome sequencing and Hi-C chromatin conformation capture to assemble the first telomere-to-telomere (T2T) genome of this species: 21.44 Mb in nine gap-free chromosomes, with telomeric repeats recovered at all 18 chromosome ends. Phylogenomic analysis of nine Tremellales genomes, including the type species of Phaeotremella, placed T. sanguinea within Phaeotremella as sister to P. skinneri (divergence 24.50 Ma; 95% HPD 22.14–26.89) rather than within Tremella sensu stricto, corroborating at genome scale a placement previously indicated by multi-locus data, providing the first divergence-time estimates for the lineage, and reconciling its position with its dark, foliose basidiocarp morphology. Gene family evolution was contraction-biased, most strongly at the Phaeotremella crown node (92 expansions vs. 855 contractions). The carbohydrate-active enzyme repertoire of T. sanguinea (185 genes) fell within the range reported for Tremellales, whereas families that expanded on its branch were significantly enriched for transport functions, including dipeptide and allantoate transport. These results indicate that T. sanguinea acquires host-derived nutrients through uptake of small molecules rather than through an expanded hydrolytic repertoire, and provide genomic evidence for revising its generic placement within the segregate genera of Tremella sensu lato.

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.