Molecular and biochemical studies on phytonutrient accumulation in peach fruit

Carotenoids are plant metabolites which are not only essential in photosynthesis but also important quality factors in determining the pigmentation and aroma of flowers and fruits. The expression patterns of relevant carotenoid genes and metabolites were studied throughout fruit development, in order to investigate carotenoid metabolism and the relationships between ethylene emission and carotenoid production in peaches (Prunus persica L. Batsch.). Four cultivars with different flesh colour (yellow vs. white) and/or flesh type (melting vs. stonyhard) were analyzed throughout the fruit development cycle. 'Redhaven Bianca', the white-fleshed mutant of 'Redhaven', showed the highest levels of ccd1 expression at all stages of fruit development. The dioxygenase genes family, in peach as in other species, is directly involved in carotenoid degradation and the concomitant emission of volatile substances with a high odour impact. In both white-fleshed stony-hard genotypes, however, this gene was very poorly expressed in the fruit, suggesting that the stony-hard trait interacts with the metabolism/catabolism of carotenoids.