2024/12/23 by Quan Sun, Zhengchen He, Ranran Wei +5 · 1 voice
Biochemistry, Genetics and Molecular Biology · Medicine · #Plant Gene Expression Analysis #Antioxidant Activity and Oxidative Stress #Plant biochemistry and biosynthesis
paper · doi:10.1093/plcell/koaf010
openalex publication_date 2024/12/23 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The reddish apocarotenoid β-citraurin, produced by CAROTENOID CLEAVAGE DIOXYGENASE 4b (CsCCD4b), is responsible for peel reddening in citrus (Citrus spp.). Ethylene induces the characteristic red color of citrus peel, but the underlying molecular mechanism remains largely unclear. Here, we identified red peel regulator 1 (CsRP1), a trihelix transcriptional activator that regulates ethylene-induced peel reddening by directly binding to a key V-myb avian myeloblastosis viral oncogene homolog (MYB)-binding site in the CsCCD4b promoter, thus activating its transcription. Furthermore, 2 drought-responsive cis-elements in the CsRP1 promoter are bound by the ethylene response factor ethylene response factor 25 (CsERF25). We reconstructed the CsERF25-CsRP1-CsCCD4b transcriptional regulatory cascade through transient expression of CsERF25 and CsRP1 in citrus peel and via stable transformation of citrus calli. In this cascade, CsERF25 expression was induced by ethylene to activate CsRP1 expression, and then, CsRP1 directly induced CsCCD4b transcription to catalyze β-citraurin biosynthesis. CsRP1 and CsERF25 also bound to the promoters of other carotenogenic genes and induced their transcription, thereby promoting β-citraurin accumulation. Collectively, our findings reveal a complex regulatory network modulating ethylene-induced citrus peel reddening and provide innovative strategies for improving the nutritional and esthetic values of citrus and other fruit crops.