Chromosome-Level Genome Assembly of Morchella sextelata Reveals Its Early Divergence and Adaptive Evolution

This study presents a high-quality chromosome-level genome assembly of Morchella sextelata (54.64 Mb, 26 pseudochromosomes) and systematically characterizes its genomic and evolutionary features. Phylogenetic analysis indicates that M. sextelata diverged early within the Morchella genus (~14.2 million years ago) and underwent substantial genomic remodeling, with 1124 expanded and 1961 contracted gene families. Enrichment analysis of rapidly expanded gene families highlights two prominent functional themes: genes associated with small molecule/ion binding and secondary metabolite biosynthesis, and genes linked to the Fanconi anemia pathway and DNA repair/recombination. Notably, 56.96% of the COG-annotated M. sextelata-specific genes encode retrotransposon-related proteins, and this enrichment coincides with the expansion of DNA repair systems-a pattern reminiscent of the "transposon domestication" model. Functional genomic analyses further reveal that the glycoside hydrolase system is dominated by GH5, GH43, and GH3 families, suggesting a predicted capacity for plant cell wall polysaccharide degradation, while 12 biosynthetic gene clusters indicate genetic potential for terpenoid and non-ribosomal peptide biosynthesis. These findings provide a valuable genomic resource for M. sextelata and offer new insights into the role of transposable element mediated remodeling in fungal genome evolution.