UC Davis

Abstract Background Peach [Prunus persica (L.) Batsch] is an economically important fruit crop that has become a genetic-genomic model for all Prunus species in the family Rosaceae. A doubled haploid reference genome sequence length of 227.3 Mb, a narrow genetic base contrasted by a wide phenotypic variability, the generation of cultivars through hybridization with subsequent clonal propagation, and the current accessibility of many founder genotypes, as well as the pedigree of modern commercial cultivars make peach a model for the study of inter-cultivar genomic heterogeneity and its shaping by artificial selection. Results The quantitative genomic differences among the three genotypes studied as genomic variants, included small variants (SNPs and InDels) and structural variants (SV) (duplications, inversions and translocations). The heirloom cultivar 'Georgia Belle’ and an almond by peach introgression breeding line 'F8,1-42’ are more heterogeneous than is the modern cultivar 'Dr. Davis’ when compared to the peach reference genome ('Lovell’). A pair-wise comparison of consensus genome sequences with 'Lovell’ showed that 'F8,1-42’ and 'Georgia Belle’ were more divergent than were 'Dr. Davis’ and 'Lovell’. Conclusions A novel application of emerging bioinformatics tools to the analysis of ongoing genome sequencing project outputs has led to the identification of a range of genomic variants. Results can be used to delineate the genomic and phenotypic differences among peach genotypes. For crops such as fruit trees, the availability of old cultivars, breeding selections and their pedigrees, make them suitable models for the study of genome shaping by artificial selection. The findings from the study of such genomic variants can then elucidate the control of pomological traits and the characterization of metabolic pathways, thus facilitating the development of protocols for the improvement of Prunus crops.