Identifying a Carotenoid Cleavage Dioxygenase (ccd4) Gene Controlling Yellow/White Fruit Flesh Color of Peach

Peach flesh color is a monogenic trait with the white phenotype being dominant over the yellow; its expression has been reported to be determined by a carotenoid degradative enzyme. In the present study, a carotenoid cleavage dioxygenase (ccd4) gene was analyzed to test whether it can be responsible for the flesh color determinism. The analysis was conducted on chimeric mutants with white and yellow sectors of the fruit mesocarp; it was then extended to a pool of cultivars and a segregating F-1 population. A ccd4 functional allele is consistently associated with the ancestral white flesh color; on the other hand, the yellow phenotype originated from at least three independent mutations disrupting ccd4 function, thus preventing carotenoid degradation. In addition, retro-mutations recovering ccd4 function and re-establishing the ancestral white flesh color were detected. Our results show that ccd4 is the gene controlling flesh color in peach; its expression results in the degradation of carotenoids in white-fleshed genotypes, while the yellow color arises as a consequence of its inactivation.