Chlorophylls and carotenoids are 2 pivotal photosynthetic pigments directly influencing the economic value of pepper (Capsicum annuum L.) fruits. However, the coordinated regulatory mechanisms governing the accumulation of both chlorophylls and carotenoids during pepper fruit development remain elusive. In this study, pepper B-box 10 (CaBBX10), a candidate hub transcription factor, was found to play dual roles in the early development of pepper fruit. CaBBX10 virus-induced gene silencing and overexpression experiments demonstrated that the encoded transcription factor promotes both chlorophyll and carotenoid accumulation in pepper fruit. Further comprehensive analyses showed that CaBBX10 directly binds to the promoter of magnesium chelatase subunit D subunit (CaCHLD) and phytoene synthase 1 (CaPSY1), thereby activating their expression in the chlorophyll and carotenoid biosynthesis pathways, respectively. Additionally, the photomorphogenic factor CaCOP1 was found to physically interact with CaBBX10 and lead to its degradation. Therefore, CaBBX10 may serve as a critical link connecting chlorophyll and carotenoid biosynthesis to light signaling. Altogether, our findings reveal a mechanism for the complex transcriptional regulation that simultaneously promotes chlorophyll and carotenoid accumulation in pepper fruit.

中文翻译：

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转录因子 CaBBX10 促进辣椒果实中叶绿素和类胡萝卜素色素的积累


叶绿素和类胡萝卜素是直接影响辣椒 （Capsicum annuum L.） 果实经济价值的 2 种关键光合色素。然而，在辣椒果实发育过程中控制叶绿素和类胡萝卜素积累的协调调节机制仍然难以捉摸。在这项研究中，发现辣椒 B-box 10 （CaBBX10） 是一种候选枢纽转录因子，在辣椒果实的早期发育中起双重作用。CaBBX10 病毒诱导的基因沉默和过表达实验表明，编码的转录因子促进辣椒果实中叶绿素和类胡萝卜素的积累。进一步综合分析表明，CaBBX10 直接与镁螯合酶亚基 D 亚基 （CaCHLD） 和植物烯合酶 1 （CaPSY1） 的启动子结合，从而分别激活它们在叶绿素和类胡萝卜素生物合成途径中的表达。此外，发现光形态发生因子 CaCOP1 与 CaBBX10 发生物理相互作用并导致其降解。因此，CaBBX10 可以作为连接叶绿素和类胡萝卜素生物合成与光信号传导的关键环节。总而言之，我们的研究结果揭示了一种复杂转录调控的机制，该机制同时促进辣椒果实中叶绿素和类胡萝卜素的积累。