Genome assembly of M. spongiola and comparative genomics of the genus Morchella provide initial insights into taxonomy and adaptive evolution.

Abstract

Morchella spongiola is a highly prized mushroom for its delicious flavor and medical value and is one of the most flourishing, representative, and dominant macrofungi in the Qilian Mountains of the Qinghai-Tibet Plateau subkingdoms (QTPs). However, the understanding of M. spongiola remains largely unknown, and its taxonomy is ambiguous. In this study, we redescribed a unique species of M. spongiola, i.e., micromorphology, molecular data, genomics, and comparative genomics, and the historical biogeography of M. spongiola were estimated for 182 single-copy homologous genes. A high-quality chromosome-level reference genome of M. spongiola M12-10 was obtained by combining PacBio HiFi data and Illumina sequencing technologies; it was approximately 57.1Mb (contig N50 of 18.14Mb) and contained 9775 protein-coding genes. Comparative genome analysis revealed considerable conservation and unique characteristics between M. spongiola M12-10 and 32 other Morchella species. Molecular phylogenetic analysis indicated that M. spongiola M12-10 is similar to the M. prava/Mes-7 present in sandy soil near rivers, differentiating from black morels ~ 43.06 Mya (million years ago), and diverged from M. parva/Mes-7 at approximately 12.85 Mya (in the Miocene epoch), which is closely related to the geological activities in the QTPs (in the Neogene). Therefore, M. spongiola is a unique species rather than a synonym of M. vulgaris/Mes-5, which has a distinctive grey-brown sponge-like ascomata. This genome of M. spongiola M12-10 is the first published genome sequence of the species in the genus Morchella from the QTPs, which could aid future studies on functional gene identification, germplasm resource management, and molecular breeding efforts, as well as evolutionary studies on the Morchella taxon in the QTPs.