Hu Yang, Gong Zhiqian, Yan Yiming, Zhang Jiating, Shao Anping, Li Hao, Wang Pengfei, Zhang Shuai, Cheng Chunzhen, Zhang Jiancheng
College of Horticulture, Shanxi Agricultural University, Taigu 030801, China.
College of Horticulture, Shanxi Agricultural University, Taigu 030801, China.
Int J Biol Macromol. 2024 Dec;282(Pt 4):137195. doi: 10.1016/j.ijbiomac.2024.137195. Epub 2024 Nov 1.
B-box zinc-finger transcription factor (BBX) plays important regulatory roles in plant secondary metabolism. Here, we identified 21 BBXs that could be further categorized into five subfamilies from Cerasus humilis. Two segmentally duplicated Subfamily IV members, ChBBX6 and ChBBX18, were found to share high homology with reported anthocyanin-related BBXs and express highly in fruits with high anthocyanins but low carotenoids contents. Their transient overexpression in apple and C. humilis fruits both led to significantly increased anthocyanins accumulation and significantly upregulated expression of anthocyanins-related genes. However, their overexpression resulted in decreased carotenoids accumulation and greatly upregulated the expression of carotenoids-related genes especially degradation-related genes. Additionally, their overexpression both greatly improved the ABA content in C. humilis fruits. Through yeast one-hybrid and dual-luciferase reporter assays, we found that both ChBBX6 and ChBBX18 could bind to and activate the promoters of chalcone synthase (ChCHS), flavanone 3-hydroxylase (ChF3H), and 9-cis-epoxycarotenoid dioxygenase 5 (ChNCED5). Our study demonstrates that ChBBX6 and ChBBX18 are positive regulators of anthocyanins biosynthesis and carotenoids degradation and can provide basis for understanding the roles of BBX genes in C. humilis.
B-box锌指转录因子（BBX）在植物次生代谢中发挥着重要的调控作用。在此，我们从郁李中鉴定出21个BBX，它们可进一步分为五个亚家族。发现两个片段重复的IV亚家族成员ChBBX6和ChBBX18与已报道的花青素相关BBX具有高度同源性，且在花青素含量高但类胡萝卜素含量低的果实中高表达。它们在苹果和郁李果实中的瞬时过表达均导致花青素积累显著增加，以及花青素相关基因的表达显著上调。然而，它们的过表达导致类胡萝卜素积累减少，并极大地上调了类胡萝卜素相关基因尤其是降解相关基因的表达。此外，它们的过表达均极大地提高了郁李果实中的脱落酸含量。通过酵母单杂交和双荧光素酶报告基因检测，我们发现ChBBX6和ChBBX18均能结合并激活查尔酮合酶（ChCHS）、黄烷酮3-羟化酶（ChF3H）和9-顺式环氧类胡萝卜素双加氧酶5（ChNCED5）的启动子。我们的研究表明，ChBBX6和ChBBX18是花青素生物合成和类胡萝卜素降解的正调控因子，可为理解BBX基因在郁李中的作用提供依据。
