Abstract
We isolated a sporulation-deficient (sporeless) mutant (B682) of Lentinula edodes using UV-irradiation. The number of basidiospores falling from the mature fruiting body was approximately 1/10,000 of the original (wild-type) strain. Scanning electron microscopy observation showed negligible mature spores on the hymenium surface; however, immature spores were frequently observed. Using HCl-Giemsa staining for basidia of mutant fruiting bodies, eight nuclei were observed in each basidium, suggesting that somatic division of four daughter nuclei occurred after meiosis. Genetic analysis using the tester-population (98115A population) suggested that the sporeless trait resulted from a single dominant factor. Based on next-generation sequencing for original and mutant genomes, single-nucleotide polymorphism (SNP) with nonsense mutation was found, and its inheritance was confirmed in sporeless segregants from the 32D tester-population. From this result, B682 is the first dominant sporeless mutant of L. edodes and is a biological material for studying the sporulation mechanism in basidiomycetes. Furthermore, the SNP is presumably an effective mutation point that enables marker-assisted selection in promoting breeding utilization of sporeless mutation.
