Mating-Type Genes Play an Important Role in Fruiting Body Development in Morchella sextelata

Abstract

True morels (Morchella spp.) are edible mushrooms that are commercially important worldwide due to their rich nutrition and unique appearance. In recent years, outdoor cultivation has been achieved and expanded on a large scale in China. However, the mechanisms of fruiting body development in morels are poorly understood. In this study, the role of mating-type genes in fruiting body development was researched. Fruiting bodies cultivated with different mating-type strains showed no difference in appearance, but the ascus and ascospores were slightly malformed in fruiting bodies obtained from the MAT1-1 strains. The transcript levels of mating-type genes and their target genes revealed that the regulatory mechanisms were conserved in ascomycetes fungi. The silencing of mat1-2-1 by RNA interference verified the direct regulatory effect of mat1-2-1 on its target genes at the asexual stage. When cultivated with the spawn of single mating-type strains of MAT1-1 or MAT1-2, only one corresponding mating-type gene was detected in the mycelial and conidial samples, but both mat1-1-1 and mat1-2-1 were detected in the samples of primordium, pileus, and stipe. An understanding of the mating-type genes’ role in fruiting body development in M. sextelata may help to understand the life cycle and facilitate artificial cultivation.

Large-Scale Field Cultivation of Morchella and Relevance of Basic Knowledge for Its Steady Production

“…Similarly, it has been shown that when cultivated with the spawn of single mating-type strains of mat1-1 or mat1-2, only one corresponding mating-type gene was detected in the mycelium and conidia. However, in contrast, in primordia, pileum and stipe were both MAT (mating types) [ 54 ].…”

“…Despite the fact that the disproportion between the two mating genotypes was found in a variety of ascomycetes, it seems to be particularly abundant in Morchella [ 55 , 56 ]. We have tested the mating type proportions of commercially cultivated strains.…”

“…In different parts of mature ascomata with seriously unbalanced mating types, from the base of the stipe, the middle of the stipe, the junction of the stipe and the cap, to the middle and top of the pileus, the proportion difference between the two mating type genes gradually decreased ( Figure 6 ). Based on these results, we speculated that there was heterogeneity in the spatial distribution of the nuclei represented by the two mating genotypes and that there was competition at the nuclear level [ 56 ]. The serious disproportion was the complete loss of a mating type among the tissue isolated populations, which occurred in the tissue-isolated populations of M. importuna , M. sextelata , M. eximia , and Mel-21, i.e., most of the strains in these isolated populations contain only one mating karyotype [ 56 , 57 ].…”

“…Based on these results, we speculated that there was heterogeneity in the spatial distribution of the nuclei represented by the two mating genotypes and that there was competition at the nuclear level [ 56 ]. The serious disproportion was the complete loss of a mating type among the tissue isolated populations, which occurred in the tissue-isolated populations of M. importuna , M. sextelata , M. eximia , and Mel-21, i.e., most of the strains in these isolated populations contain only one mating karyotype [ 56 , 57 ]. This made it necessary to detect mating-type genes if tissue-isolated strains wanted to be used for cultivation purposes.…”

Science and technology breakthroughs to advance artificial cultivation of true morels

“…(Tan et al, 2019 ; Liu et al, 2020 , 2021a ; Du and Yang, 2021 ; Chai et al, 2022 ). However, there is still a lack of understanding of conidial production, working mechanisms of exogenous nutrition bags, primordium formation, and fruiting body development mechanisms (Liu et al, 2022 ), so basic research should be continued.…”