AC/GT and AG/CT microsatellite repeats in peach [Prunus persica (L) Batsch]: isolation, characterisation and cross-species amplification in Prunus

We report the sequences of 17 primer pairs of microsatellite loci, which we have cloned and sequenced from two genomic libraries of peach [Prunus pers ica (L) Batsch] 'Redhaven', enriched for AC/GT and AG/CT repeats respective ly. For ten of these microsatellite loci we were able to demonstrate Mendel ian inheritance in a segregating back-cross population: the remainder did n ot segregate. The polymorphism of the microsatellites was evaluated in a pa nel of ten peach genotypes, including true-to-type peaches, nectarines and one canning-peach. Fifteen microsatellites (88%) were polymorphic showing 2 -4 alleles each. The mean heterozygosity, averaged over all loci, was 0.32 and significantly higher than that reported in the literature for isozymes and molecular markers, such as RFLPs and RAPDs. We have also assayed the cr oss-species transportability and found that ten microsatellite (59%) gave a pparently correct amplification in all Prunus species surveyed, namely P. d omestica (European plum), P. salicina (Japanese plum), P. armeniaca (aprico t), P. dulcis (almond), P. persica var. vulgaris (peach). P. persica var. l aevis (nectarine), P. avium (sweet cherry) and P. cerasus (sour cherry), wi th three of them also being amplified in Malus (apple). The remaining micro satellites gave less-extensive amplification. Because of their appreciable polymorphism and wide cross-species transportability, most of these new mar kers can be integrated into the linkage maps which are currently being cons tructed in peach, as well as in other stone fruit crops, such as almond, ap ricot, cherry and plum.