Loci Important for Peach and Cherry Fruit Size and Quality: What Is Known about Their Functional Alleles?

Peach and cherry are the two Prunus stone fruit crops that are currently targeted in RosBREED for the adoption of marker-assisted breeding. Peach serves as a well resourced model fruit crop while cherry stands to directly benefit from research advances in its relative. Three “jewels in the genome” for peach and cherry are the current targets for application in breeding. Peach breeders select cultivar candidates that meet their criteria for fruit texture (melting vs. non-melting flesh) and pit adherence to the flesh (clingstone vs. freestone). These phenotypes are explained by genes at the Freestone-Melting flesh locus on peach chromosome 4 that contains the endoPG gene (a gene encoding a cell wall pectin-cleaving enzyme called endopolygalactouronase that plays a major role in fruit softening). Genetic tests are available for the functional alleles that can be used to predict whether peach fruit will be freestone melting flesh (FMF), clingstone melting flesh (CMF), clingstone non-melting flesh (CNMF), or clingstone non-softening flesh (CNSF). In sweet cherry, fruit size is a critical trait for breeding as larger fruit receives a premium price in the market place. A QTL for fruit size on cherry chromosome 2 exhibits multiple functional alleles associated with large, medium, or small fruit. Knowledge of the functional alleles for these marker-locus-trait associations will be presented along with how this knowledge is being used to increase the efficiency of breeding peaches and cherries with superior fruit quality.