Fruit Characters and Volatile Organic Components in Peach-to-Nectarine Mutants

Peach-to-nectarine mutants showed broad pleiotropic effects on fruit size, taste, and aroma, in addition to hairlessness. In this study, we compared nine fruit attributes and 27 detected volatiles in the peach progenitor, ‘Flameprince’ (FPP), its two independently discovered peach-to-nectarine mutants (HFN and PFN), and a selected nectarine hybrid (SLN). HFN and PFN differed from FPP in fruit size and taste, but shared high similarities in fruit blush coverage and pattern, pit shape, and flesh and pit color. Compared to FPP, the two mutants were significantly lighter and smaller, but higher in soluble solids content (SSC), titratable acidity (TA), and the SSC/TA ratio. The 27 volatiles varied among the cultivars and harvest dates, in terms of total abundance and detection rate, which could be roughly clustered into six subgroups. Subgroup 1 included five volatiles and two fruit attributes that were low on Aug 6 but dramatically increased on Aug 13. Subgroup 2 had a similar tendency to subgroup 1 but one of the cultivars was an exception. Subgroup 3 included those that had the opposite tendency to subgroup 1 or 2. Volatiles in the three subgroups appeared closely associated with the ripening process. Fruit volatiles and attributes in the other three subgroups generally were inconsistent among the four cultivars on the two dates. Hexanol was the only volatile undetected in the peach, but detected in the three nectarines. Differences in broad pleiotropic effects among these mutants, potential utilization of volatiles, and genomic exploration are discussed.