Cultivation and mating of the truffle Tuber japonicum in plantations of ectomycorrhizal Quercus serrata seedlings.

Tuber japonicum, a white-colored truffle that is endemic to Japan, is promising for culinary purposes due to its unique aroma. We were able to cultivate T. japonicum in plantations of inoculated Quercus serrata seedlings for the first time. Ascocarps were found after 43 months at one site and after 61 months at another. We developed simple sequence repeat markers for multilocus genotyping of glebal tissue and ascospores and confirmed that the harvested ascocarps were derived from inocula. All paternal individuals matched the multilocus genotypes of neighboring maternal individuals, indicating frequent hermaphroditism and the absence of externally introduced individuals. Our findings provide important clues to understanding the reproductive biology of T. japonicum during the early period after the truffle plantation establishment. IMPORTANCE: Truffles are highly prized as a delicacy, but only a select few species have been successfully cultivated. In our study, we succeeded for the first time in cultivating Tuber japonicum. Two out of four plantations produced ascocarps shortly after planting, with one of them yielding a comparable weight to other cultivated truffle species. This promising productivity suggests that the fungus has potential when cultivated. Our analysis of the ascocarps' maternal and paternal genotypes, using simple sequence repeat markers, revealed hermaphroditic behavior in the fungus at our planting site. Our findings provide crucial insights into the truffle mating events.