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Morels (Morchella spp.) are highly prized for their culinary qualities and intensively collected worldwide by mycophiles. Morels are divided into three clades by phylogenetic analyses: black morels, yellow morels and the rufobrunnea clade. Morchella importuna, Mel-20 and M. sextelata are included in the black morel clade and are widely distributed in Yunnan province, China. M. importuna and M. sextelata have been artificially cultured in recent years, but their life cycles and reproductive systems are still poorly understood, which delays the progress of morel cultivation. In this study, the genomes of two ascospore isolates of M. importuna with opposite mating-type were sequenced and two idiomorphs, MAT1–1 and MAT1–2, were identified. The MAT1–2 idiomorph was 6.7 kb in length containing a single MAT1–2-1 gene, and the MAT1–1 idiomorph was 10.5 kb containing a MAT1–1-1 gene and two other open reading frames (ORFs), GME3123 and GME3124. These ORFs differed greatly from the homologues of previously published mating-type genes; therefore, we speculate that they are novel mating genes found only in morels. Single-ascospore populations of M. importuna, M. sextelata and Mel-20 were analysed, and the result indicated that the ratios of MAT1–1- and MAT1–2-harbouring idiomorphs were not significantly different from a 1:1 ratio. The results suggest that these three black morels are heterothallic.

The difference of gene expression between sclerotia-producing and non-sclerotia-producing single spore isolates from Morchella conica were preliminary analyzed by mRNA differential display reverse transcription-polymerase chain reaction (RT-PCR) technique and 67 differential gene fragments were obtained. Fifty-eight of their second PCR products were cloned and sequenced. Thirteen special differential gene fragments related to sclerotial formation were validated by semi-quantitative RT-PCR. Some gene fragments had certain homologies with lipoprotein, cyclin-dependent kinase C-3, glycerophosphoryl diester phosphodiesterase, Rho GDP-dissociation inhibitor, gamma-aminobutyrate permease, OmpA family protein, Transcript antisense to ribosomal RNA protein, sodium–calcium exchange protein and keratin-associated proteins 5, 6. In addition, the putative protein of some DNA fragments had higher similarity with hypothetical protein-coding gene in NCBI database, as well as some were only putative gene fragments. All these fragments were speculated to be the functional gene associated with sclerotial formation in morel.