2018 ASHS Annual Conference

Sweet cherry (Prunus avium L.) is a clonally propagated, diploid, outcrossing crop for which cultivar development uses a pedigree-based breeding approach. Although sweet cherry breeding has been conducted in the Pacific Northwest for more than half a century, genetic structure of this sweet cherry germplasm is not well understood based only on incomplete pedigree records. In this study, a pedigreed population of 65 elite and wild sweet cherry clones and 463 unselected offspring from 86 crosses in the Washington State University sweet cherry breeding program, comprising a germplasm set established to be representative of U.S. public breeding germplasm for this crop, was genotyped with the RosBREED Illumina Infinium® 6K cherry SNP array. After data curation, a total of 1617 robust SNPs were identified and used to define 196 haploblocks (HB) delimited by historical recombinations. Many parentage records were corrected or deduced using this most detailed-yet genotypic dataset. Several statistical parameters were calculated including minor allele frequency, heterozygosity, polymorphic information content, inbreeding coefficient, and relatedness coefficient to understand genetic structure. A high degree of relatedness among many founders was discovered. The quantitative genetic relationships among ancestral and elite individuals as well as the particular shared haplotypes and other patterns of allelic variation revealed will be useful for informing breeding decisions.