Characterization and evaluation of genetic diversity in peach germplasm using RAPD and RFLP markers

Fifty-two peach genotypes, nine nectarines, one almond (Ferragnes) and four peach x almond hybrids were tested using RAPDs. Thirty-nine of the peach genotypes were also tested using 28 RFLP probes from two almond libraries (genomic and cDNA) obtained by IRTA of Cabrils (Spain). A total of 115 primers were screened for their ability to produce strongly amplified products. Out of 79 (68.7%) primers, with a strong amplification, 42 (53.2%) showed polymorphisms among the tested genotypes. Eight of these were considered as the most informative producing 24 polymorphic reliable bands. A set of five primers (OPA9, OPA14, OPK19, OPJ13 and OPP9), for a total of 16 RAPDs, proved to be enough to discriminate 39 genotypes (59.1%). Eleven additional patterns characterized more than one genotype. The remaining polymorphic bands did not add further information for distinguishing those genotypes showing the same profile. Using RFLPs, from nine polymorphic probes (out of 28 tested) we obtained 17 markers. They permitted to discriminate 16 (41.0%) genotypes, out of the 39 tested, and nine patterns characterizing more than one genotype. The undiscriminated genotypes were the same in both trials. The complete set of 61 RAPD bands (24 polymorphic) and of 55 RFLP bands (17 polymorphic) were separately analyzed by cluster analysis using NTSYS version 1.80. The similarity indexes obtained from RAPD and RFLP are quite the same varying from about 80% to 100%. The results confirmed the high degree of inbreeding within the peach genotypes tested.