The Development of Molecular Markers for Peach Skin Blush and Their Application in Peach Breeding Practice

Peach is an economically important fruit tree crop worldwide. The external color of the fruit governs the peach price, especially in fruits with different degrees of blush. Molecular marker-assisted breeding has become a necessary part of modern breeding practices, increasing their efficiency. Although the key related genes responsible for peel coloration have been found in peach, corresponding molecular markers have not been widely used in peach breeding. The development of molecular markers for peach peel color needs to be advanced and implemented in practice. This study aimed to explore the variation related to peach skin color and to develop molecular markers linked to these variants that can be used in breeding. By analyzing the expression of anthocyanin synthesis-related and regulatory genes, we confirmed that MYB10.1 is a key gene controlling skin color. We further identified that 5243 bp insertion and 483 bp deletion in the MYB10.1 promoter was highly associated with peach skin color phenotypes. In addition, we identified one transposon insertion mutation at the -2706 bp position of the MYB10.1 promoter associated with the non-red fruit skin trait and developed a molecular marker for validation. The insertion size amplified from the 'ShiYuBaiTao' genome DNA was approximately 3.5 kb. However, it explained a lower percentage of the non-red skin phenotype variance in peach, at 36.1%, compared to MYB10.1-2/MYB10.1-2 in this study. Based on these results, we propose that MYB10.1-2/MYB10.1-2 should not only be the only non-red skin genotype assessed but should also be combined with other molecular makers to increase the prediction accuracy of peach skin color.