Flesh to Stone Adhesion
The gene encoding cell-wall degrading enzyme, endopolygalacturonase (endoPG) is responsible for the F-M locus, the major locus controlling flesh-to-stone adhesion and melting/non-melting traits in peach. endoPG is multiallelic and hyper variable and variation within each major allele may have a quantitative effect on texture. Several ripening-related candidate genes have been mapped to various locations on the peach genome. A quantitative analysis of these traits may reveal other genomic regions comprising modifier genes or previously unidentified functional genes.
Flesh bleeding (redness around the stone) is a genetic trait present in many fresh market peach and nectarine cultivars that can give an attractive appearance to fresh fruit, but is detrimental in the canning process as the redness becomes brown and unsightly, and can leak into canning syrup. This trait was mapped as a single locus (Cs) to G3 of peach. However, the occurrence of endocarp staining suggests a quantitative inheritance. A quantitative analysis of endocarp staining may reveal genomic regions other than Cs.
Flesh browning is a discoloration of the flesh which can occur in mealy and non-mealy fruits of both fresh market and canning peaches, though it is often associated with mealiness. Several QTLs controlling bleeding and browning have been localized and a major browning QTL co-located with a gene encoding leucoanthocyanidin dioxygenase (PpLDOX) enzyme of the anthocyanin biosynthesis pathway.