Genetic structure and long-term genetic diversity assessment of Burgundy truffle populations in central Europe

The life cycle and population dynamics of truffles, including the Burgundy or summer truffle, Tuber aestivum, remain enigmatic due to their subterranean development and reliance on mature fruiting bodies for detection. This study leverages one of the longest-running truffle monitoring programs to date, spanning 2011–2023 across 23 populations in Switzerland and Germany, to explore the genetic structure and persistence of T. aestivum. Employing microsatellite marker genotyping, the findings revealed distinct population structures, particularly the differentiation of genetic cluster 3, characterized by the presence of private alleles, high differentiation values, limited admixture and over 85% probability of assignment to the genetic group, as well as a significant isolation by distance correlation. A maximum lifespan of 11 years for single multi-locus genotype (MLG) was documented, notably extending the known persistence of truffle genotypes. This longevity indicates the potential dominance of long-lived maternal genotypes in certain populations, which may adopt K-strategist reproductive strategies. Conversely, other populations exhibited higher genetic turnover and diversity, consistent with r-strategist behaviors. This confirms the previously found diverse recombination and colonization patterns of the species. Despite the challenges posed by the clonality of the organism, uneven sample sizes and heterogeneity in data collection, the study’s time-series analysis with the use of Nei’s genetic diversity (Hexp) contribute to a growing understanding of T. aestivum’s adaptive strategies and provide the basis for further research that elucidates the life history of hypogeous fungi.