ERF5.1 modulates carotenoid accumulation by interacting with CCD4.1 in Lycium

Carotenoids are important natural pigments and have medical and health functions for humans. Carotenoid cleavage dioxygenase 4 ( ) and ethylene responsive factor (ERF) participate in carotenoid metabolism, but their roles in have not been discovered. Here, we annotated s from the reference genome and found that expression was significantly correlated with the carotenoid metabolites during five fruit developmental stages. Over-expression of in NQ's leaves resulted in a series of significantly lower contents of carotenoid metabolites, including β-carotene and β-cryptoxanthin. Moreover, , a transcription factor belonging to the ERF family that was located in the nucleus, was isolated. Significant reductions in the carotenoids, especially lutein, violaxanthin and their derivatives, were observed in over-expressing transgenic NQ's leaves. Over-expression or virus-induced gene silencing of in NQ's leaves induced a consistent up- or down-expression, respectively, of . Furthermore, yeast one-hybrid and dual-luciferase reporter assays showed that interacted with the promoter of to increase its expression, and could bind to any one of the three predicted binding sites in the promoter of . A transcriptome analysis of and over-expressed lines showed similar global transcript expression, and geranylgeranyl diphosphate synthase, phytoene synthase, lycopene δ-cyclase cytochrome, cytochrome P450-type monooxygenase 97A, cytochrome P450-type monooxygenase 97C, and zeaxanthin epoxidase in the carotenoid biosynthesis pathway were differentially expressed. In summary, we uncovered a novel molecular mechanism of carotenoid accumulation that involved an interaction between and , which may be used to enhance carotenoid in .