Combination of Simple Sequence Repeat, S-Locus Polymorphism and Phenotypic Data for Identification of Tunisian Plum Species (Prunus spp.)

Plums (Prunus spp.) are among the first fruit tree species that attracted human interest. Artificial crosses between wild and domesticated species of plums are still paving the way for creation of new phenotypic variability. In Tunisia, despite a considerable varietal richness of plum as well as a high economic value, the plum sector is experiencing a significant regression. The main reason of this regression is the absence of a national program of plum conservation. Hence, this work was aimed to phenotypically and genetically characterize 23 Tunisian plum accessions to preserve this patrimony. Closely related Prunus species from the same subgenus may be differing at two characteristics: ploidy level and phenotypic traits. In this study, single sequence repeat (SSR) markers allowed distinguishing between eighteen diploid accessions and five polyploid accessions, but SSR data alone precluded unambiguous ploidy estimation due to homozygosity. In contrast, S-allele markers were useful to identify the ploidy level between polyploid species, but they did not distinguish species with the same ploidy level. Seven out of 12 phenotypic traits were shown to be discriminant traits for plum species identification. Molecular and phenotypic traits were significantly correlated and revealed a powerful tool to draw taxonomic and genotypic keys. The results obtained in this work are of great importance for local Tunisian plum germplasm management.