Genetic relationships between peach (Prunus persica (L.) Batsch) and closely related wild species using SSR markers

The genetic relationships between several genitors used in peach breeding programmes, including two commercial peach cultivars [Prunus persica (L.) Batsch], six peach seed-propagated rootstocks and six accessions of related wild species including Prunus mira, Prunus kansuensis and Prunus davidiana, were studied using 28 SSR markers. The total number of alleles revealed by SSR analysis varied from 3 to 9 with an average of 6.2. The level of heterozygosity ranged from 5% to 58% and was much higher in wild species (27%) than in peach genotypes (16%). Low levels were found in seed-propagated rootstocks 'Bailey', 'Pamirskij 5 ' and 'Rubira (respectively 3.7, 3.8, and 8%) and for autogamous wild species P. kansuensis and P. mira (respectively 4 and 5%). At the opposite, the highest values (from 32 to 58%) were found in allogamous wild species Prunus davidiana. Cluster analysis of these data emphasized the distinction between the peaches and wild-related species, according to their geographical origin. Polymorphism between these two groups reached 85%. Moreover, a total of 89 and 65 alleles were specific to wild species and peach respectively, whereas only 19 were common to both germplasms. Wild species closely related to Prunus persica thus appear as an interesting source of variability for peach. These results provide a soundbasis to manage breeding programmes.