Variation of Carotenoids and Polyphenolics in Peach and Implications on Breeding for Modified Phytochemical Profiles

The objective of this study was to examine the relative impact of genetics and environment on phenolic and carotenoid profiles in peach (Prunus persica) germplasm. Fully mature, (''ready-to-eat'' stage) firm fruit of peach cultivars China Pearl, Contender, and Carolina Gold were collected from established trees at two North Carolina locations in 2009 and 2010. Advanced breeding selections NC Yellow and NC 97-48 were collected from a single location in both years. Using tandem extractions and chromatography analyses, 10 carotenoids and 24 phenolic compounds were quantified separately in the peel and flesh. Statistically significant differences were noted among peach cultivars and advanced selections for b-carotene, cyanidin-3-glucoside, cyanidin-3-rutinoside, cholorogenic acid, quercetin-3-glucoside, and individual procyanidins. Peel anthocyanin (ANC) concentration ranged from 183 mg/100 g in 'Contender' to non-detectable levels in NC97-48 and NC Yellow. 'China Pearl' and 'Carolina Gold' produced ANC levels approximately half of 'Contender'. Chlorogenic acid concentration also fit a discrete pattern of accumulation but was not related to the accumulation of ANC. 'China Pearl', NC 97-48, and NC Yellow contained the highest levels of chlorogenic acid (105 to 136 mg/100 g), 'Carolina Gold' contained the lowest (52 mg/100 g), and 'Contender' represented an intermediate phenotype (70 mg/100 g). Statistically significant genetic variation was found for almost all compounds identified, whereas location and year effects tended to be compound-specific. For chlorogenic acid, 28% of the phenotypic variance was explained by location (year = nonsignificant), whereas 40% of the phenotypic variation of ANC was explained by differences in years (location = nonsignificant). Analyzing fruit from the same environment over 2 years or from two locations in the same year would not have adequately accounted for the variation associated with environment. The detailed phytochemical profile of peach reported here demonstrates the importance of multiyear, multilocation analysis in revealing accurate measures of phytochemical genetic variation and provides a comprehensive baseline analysis of phytochemicals in commonly grown peach cultivars that can be used to evaluate novel germplasm. Epidemiological studies have suggested that increased consumption of fruits and vegetables is associated with de- creased risks of chronic diseases such as cancer, diabetes, and cardiovascular disease (Arts and Hollman, 2005). It has further been suggested that these beneficial properties in fruits are largely attributable to their antioxidant capacity (Halliwell, 1996). This has led to calls from some quarters to develop peach cultivars with higher levels of total antioxidant capacity (TAC), which is measured with various chemical assays (Dalla Valle et al., 2007; Vizzotto et al., 2007). To this end, surveys of peach germplasm have identified differences in TAC as well as differences in total phenolics and/or total anthocyanin, thought to be the primary contributors to these measurements in peach