A mutant allele of ζ-carotene isomerase (Z-ISO) is associated with the yellow pigmentation of the "pinalate" sweet orange mutant and reveals new insights into its role in fruit carotenogenesis.

Abstract. Background:Fruit coloration is one of the main quality parameters of Citrus fruit primarily determined by genetic factors. The fruit of ordinary sweet orange (Citrus sinensis) displays a pleasant orange tint due to accumulation of carotenoids, representing β,β-xanthophylls more than 80% of the total content.