蜜柑
转录因子
染色质免疫沉淀
乙烯
电泳迁移率测定
发起人
化学
橙色(颜色)
锌指转录因子
锌指
柑橘×冬青
细胞生物学
类胡萝卜素
基因表达
生物化学
分子生物学
生物
基因
植物
食品科学
催化作用
作者
Quan Sun,Zhengchen He,Junli Ye,Ranran Wei,Feng Duan,Yingzi Zhang,Lijun Chai,Yunjiang Cheng,Qiang Xu,Xiuxin Deng
摘要
ABSTRACT Ethylene treatment promotes orange coloration in the flavedo of Satsuma mandarin ( Citrus unshiu Marc.) fruit, but the corresponding regulatory mechanism is still largely unknown. In this study, we identified a C2H2‐type zinc‐finger transcription factor, CitZAT4 , the expression of which was markedly induced by ethylene. CitZAT4 directly binds to the CitPSY promoter and activates its expression, thereby promoting carotenoid biosynthesis. Transient expression in Satsuma mandarin fruit and stable transformation of citrus calli showed that overexpressing of CitZAT4 inhibited CitLCYE expression, thus inhibiting α‐branch yellow carotenoid (lutein) biosynthesis. CitZAT4 overexpression also enhanced the transcript levels of CitLCYB , CitHYD , and CitNCED2 , promoting β‐branch orange carotenoid accumulation. Molecular biochemical assays, including yeast one‐hybrid (Y1H), electrophoretic mobility shift (EMSA), chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP‐qPCR), and luciferase (LUC) assays, demonstrated that CitZAT4 directly binds to the promoters of its target genes and regulates their expression. An ethylene response factor, CitERF061, which is induced by ethylene signaling, was found to directly bound to the CitZAT4 promoter and induced its expression, thus positively regulating CitZAT4‐mediated orange coloration in citrus fruit. Together, our findings reveal that a CitZAT4‐mediated transcriptional cascade is driven by ethylene via CitERF061, linking ethylene signaling to carotenoid metabolism in promoting orange coloration in the flavedo of Satsuma mandarin fruit. The molecular regulatory mechanism revealed here represents a significant step toward developing strategies for improving the quality and economic efficiency of citrus crops.
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