A Peach Germplasm Collection for Increasing the Genetic Diversity in European Breeding Programs

European breeding programs are hampered by the low intraspecific genetic diversity, which is due to the self-compatibility of this homozygous species along with the low number of genotypes introduced and thus used for breeding. In 2009, four research institutions which carried out peach breeding programs in Aragon, Catalonia, Valencia and Murcia, started a new peach germplasm collection worldwide aimed at enlarging the peach genetic diversity available for breeding. The plant material was introduced from germplasm collections located in China, Central Asia, Iran and the USA (National Germplasm Repository of Davis). Sanitary status was assessed by molecular diagnosis of known diseases caused by virus, viroid, bacteria and phytoplasm pathogens. Healthy plant material was grafted and maintained in quarantine conditions. The new germplasm collection was established in two places: Zaragoza as high chilling and Murcia as low chilling requirements. Pomological and molecular data were gathered and a public database constructed. The descriptors used were from the National Center for Genetic Resources from the INIA. Introduced budwood and seeds resulted in more than 250 new genotypes from 15 countries. The molecular analysis of a subset of the collection with 21 SSR markers evenly distributed in the genome resulted in a high number of alleles per SSR (mean A= 9.5) and low observed heterozygosity (mean Ho=0.38). Variability was further assessed by geographic origin. Population structure analysis revealed the existence of 8 subpopulations explained, in some cases, by the geographic origin of the genotypes. As a result of the project a new database containing 95 accessions and 38 variables is available.