Sweet Cherry Genomics: SNP Marker Development and Unraveling the Genetics of Fruit-Pedicel Abscission

Sweet cherry, Prunus avium, is an important crop in the US valued at more than $750 million in 2010. A lack of genomic resources has hindered the understanding of agro-economic traits in sweet cherry and subsequent breeding efforts to improve such traits. We generated and assembled 3’UTR sequencing data from Bing and Rainier developing floral buds to identify gene-linked polymorphisms and made them available publicly. Through this work, over 2000 high quality SNPs were identified within the two varieties. High resolution melting (HRM) analysis was completed to test a subset of these SNPs of which ~1/3 were found to have HRM-identifiable variation among 8 parental cherry cultivars and 13 seedlings. This information will be useful in identifying markers for important traits such as pedicel-fruit retention force, a trait essential for enabling mechanical harvesting of sweet cherry as part of a SCRI project. Varieties with a range of pedicel-fruit retention force are needed for mechanical or hand harvest of sweet cherry. Quantitative expression of several sweet cherry homologs of abscission-related genes described in model plant species was examined in the fruit-pedicel abscission zones (FPAZ) of 3 cherry varieties. Each variety was tested over a developmental time course with and without ethylene treatment. These results were correlated to PFRF to match the phenotypes with the associated gene expression data. RNAseq for the same tissues is ongoing to reveal additional genes in the development of FPAZ in sweet cherry. This work will be utilized for identifying gene-linked markers for use in breeding strategies.