GENETIC DIVERSITY OF Prunus persica (L.) Batsch AND THER SPECIES OF Prunus USING MICROSATELLITES

Mexico has three genetic breeding programs for peaches and nectarines (Prunus persica (L.) Batsch). The diversity of its germplasm at a DNA level is unknown. Therefore, the aims of this work were: 1) to characterize the diversity of three P. persica populations using microsatellites or simple sequence repeats (SSRs); 2) to genetically compare two P. persica populations from the Prunus breeding programs of the College of Postgraduates and the Center for Genetic Resources and Improvement; and 3) to extrapolate the use of these SSRs to other Prunus species. DNA was extracted from leaves of 162 individuals from three locations: Montecillo and Coatepec Harinas, State of Mexico, and Huimilpan, Querétaro. A CTAB-based protocol was used. The variation of six SSRs was examined in polyacrylamide, and the diversity statistics were obtained for loci and populations. On average, 10.8 alleles were found per locus, a polymorphic information content (PIC) of 0.66, genic diversity of 0.69, and heterozygosity of 0.49. The most polymorphic locus was UCDCH15, with a PIC of 0.84 for P. persica, and UCDCH14, with 0.9 for the other three Prunus species. Regarding P. persica populations, only five SSRs were polymorphic. The expected heterozygosity was 0.512, 0.719, and 0.621, and the observed heterozygosity was 0.334, 0.716, and 0.768 for Montecillo, Querétaro, and Coatepec Harinas, respectively, indicating that Querétaro is the most diverse, and Montecillo, the most homogenous. The similarity between Montecillo and Coatepec Harinas was 0.543, followed by Montecillo and Querétaro (0.47) and Coatepec Harinas and Querétaro (0.183). For the other Prunus species, the six SSRs were polymorphic, confirming that their use can be extrapolated to related species such as apricot (Prunus armeniaca L.), plums (P. salicina L.), and cherries (P. avium L.). This is the first report on diversity in P. persica and some related species by SSRs in Mexico.