Deletions in an endopolygalacturonase gene cluster correlate with non-melting flesh texture in peach

Endopolygalacturonase activity during softening of peach [Prunus persica (L.) Batsch] fruit is thought to be responsible for the melting flesh texture. A cDNA, PRF5, was previously identified as a fruit-related endopolygalacturonase that may be involved with the texture differences (Lester et al. 1996). We found that all eight of the non-melting flesh cultivars in this study had a deletion in at least one of their PRF5-related polygalacturonase genes, while none of the melting flesh cultivars did. There were three sources of the non-melting trait, as identified by the extent of the deletions. One source of non-melting flesh resulted in a complete deletion of PRF5-related genes while the other two sources had deletions of a subset of those genes, suggesting a cluster of polygalacturonase genes at the melting flesh locus. All of the non-melting flesh cultivars used for this study had greatly reduced or undetectable mRNA levels of PRF5-related polygalacturonase during fruit softening. Using PCR techniques, it was determined that either the PRF5 gene, or more likely, an unidentified peach polygalacturonase at the same locus, is responsible for melting flesh texture determination.