Development and utilization of a DNA diagnostic test to predict flesh color in tetraploid sour cherry (Prunus cerasus)

Fruit color in sour cherry (Prunus cerasus) is an important market-driven trait in the U.S. where the dominate cultivar ‘Montmorency’ has a brilliant red color. This unique red color allows for a distinction between sour cherries grown in the U.S. and those in Europe which have predominantly dark-purple flesh. The anthocyanin transcription factor, MYB10, has previously been shown to control flesh color in cherry and other rosaceous species. Thirteen allelic variants for the sour cherry MYB10 region were distinguished based on the linkage phase of 47 polymorphic SNPs determined using the 6K Infinium® II SNP array developed by the RosBREED project. Of these 13 haplotypes, four behaved as dominant alleles conferring dark-flesh color. No SNPs, however, were found in this region which would distinguish haplotypes conferring dark-flesh. Marker-assisted seedling selection (MASS) is a goal of the Michigan State University cherry breeding program to cull undesired seedlings before they are planted in the field. Those found to have dark-fleshed alleles could be culled if a simple DNA diagnostic tool were available. Due to the high synteny in Prunus, the peach genome sequence was used to design 36 SSRs that were screened for their ability to uniquely identify dark-fleshed haplotypes. One SSR primer pair was found to amplify fragments that successfully differentiated the two darkest-flesh haplotypes. This marker can now be used for MASS in any crosses with either of these two haplotypes to cull those individuals which are predicted to have dark-purple flesh.