Distribution of Two Mating-Type Idiomorphs in Commercially Cultivated Morchella sextelata Unveiling Unique Life Cycle of Morels

The outdoor cultivation of true morels has been successfully commercialized in China in recent years. However, unstable yields make it a high-risk business. A lack of understanding of the morel life cycle has led to chaotic spawn production processes, further affecting cultivation. In this study, the life cycle of Morchella sextelata, the most widely cultivated species of true morels, was characterized. A disproportion in the two mating-type idiomorphs, MAT1-1 and MAT1-2, was observed in the mycelia during vegetative growth, successive subcultures, and different parts of the fruiting body. Homokaryotic hyphae were found to dominate the mycelia and fruiting body of M. sextelata through the separation and detection of protoplast-regenerated single strains. The findings suggest that two homokaryotic hyphae with different mating types fuse to form heterokaryotic hyphae just before ascospore production in the life cycle of M. sextelata. The observed disproportion of mating-type idiomorphs is a primary reason for strain degeneration during spawn production. This study offers new insights into the life cycle of M. sextelata, particularly the role of mating-type distribution, which may inform strategies for improving the artificial cultivation of true morels.