Identification of key enzymes involved in the accumulation of carotenoids during fruit ripening of Lycium barbarum L. by a proteomic approach

The isobaric tag for relative and absolute quantification (iTRAQ)-based proteomic approach was used to identify the key enzymes involved in the carotenoids accumulation from flowering to maturity stage of Lycium barbarum L. A total of 1,799 differentially expressed proteins were identified, and 190 were related to carotenoids metabolism. Six enzymes, including phytoene synthase, phytoene desaturase, zeta-carotene desaturase, P450 carotenoid beta-ring hydroxylase (LUT5), neoflavin synthase and nine-cis-epoxycarotenoid dioxygenase were found to be associated with the carotenoid accumulation during L. barbarum ripening by the proteomic analysis and qRT-PCR. The changes in the chromaticity and carotenoid contents during fruit ripening were also studied. The contents of carotenoid, except violaxanthin were strongly correlated with the expression levels of the key enzymes, and the colours were strongly correlated with the contents of carotenoid. This study may contribute to further investigations of the accumulation mechanism of carotenoids in L. barbarum.