Transcriptional divergence among different mating-type strains and their cross of Morchella sextelata during the asexual stage.

Fungi differ from other eukaryotes in being hermaphroditic, lacking sexual dimorphism and relying on mating-type (MAT) loci for sexual compatibility. Previous studies indicate that mating types of Morchella sextelata exhibit sex-like characteristics, with MAT1-1 tending to act maternally and being primarily responsible for stipe and infertile hymenial tissue formation. Given that conidia have been regarded as spermatia in ascomycetes and play a paternal role, this raises questions about whether MAT1-2 possesses stronger regulatory capacity during conidiation in Morchella. In this study, the genome-wide transcriptome profiles of MAT1-1, MAT1-2, and their cross of M. sextelata were determined during conidiation. The results showed significant divergence of transcriptional response between two MAT strains, and potential transcriptional interactions between MAT loci were observed in the cross. Specifically, the MAT1-2 strain displayed greater transcriptional dynamism in conidiation than the MAT1-1 strain, while MAT1-1 gained stronger transcriptional influence in the cross, indicating divergent transcriptional capacity and interactions between two MATs. Among the four MAT genes, only MAT1-1-1 and MAT1-1-10 showed significant expression in single MAT strains during conidiation, whereas all the four MAT genes were significantly active in the cross, suggesting that MAT interactions activated MAT1-1-11 and MAT1-2-1. These findings may reflect signatures of cryptic sexual elements during asexual development of M. sextelata.