Genetic diversity of Tuber aestivum / uncinatum
Résumé
Tuber aestivum and Tuber uncinatum share a complicated common history from a taxonomic point of view. Indeed, different previous studies have shown contradictory conclusions. For some authors, Tuber aestivum and Tuber uncinatum are a single species and for others, they are two different species. In another study, we used 9 molecular markers: ITS1, ITS2, nuSSU, nuLSU, mtLSU, mtSSU, EF1α, β-tubulin and RPB2. The results show some genetic differences between samples for some of the analyzed sequences. However, no genetic differentiation that would support the separation of two different species was observed. We have concluded that Tuber aestivum and Tuber uncinatum are conspecific but do show genetic polymorphism. In this study, we have developed polymorphic microsatellites markers by Direct Shotgun Pyrosequencing 454. Among the thousands of microsatellites identified, a subset of 40 (tri-, tetra-, penta- hexa-nucleotides) was selected. 15 out of the 27 microsatellites tested in PCR were polymorphic. After preliminary analyses, results show a high level of polymorphism with 69 multilocus genotypes found over the 84 samples analyzed. This study presents for the first time the identification of polymorphic microsatellites for T. aestivum allowing us to characterize the genetic structure and the gene flow through the natural populations of this species.