Liu Wenwen, Mu Huayuan, Yuan Ling, Li Yang, Li Yuting, Li Shenchang, Ren Chong, Duan Wei, Fan Peige, Dai Zhanwu, Zhou Yongfeng, Liang Zhenchang, Li Shaohua, Wang Lijun
Beijing Key Laboratory of Grape Science and Enology and State Key Laboratory of Plant Diversity and Specialty Crops, Institute of Botany, Chinese Academy of Science, Beijing 100093, China.
China National Botanical Garden, Beijing 100093, China.
Hortic Res. 2023 Sep 1;10(10):uhad176. doi: 10.1093/hr/uhad176. eCollection 2023 Oct.
Anthocyanins are essential for the quality of perennial horticultural crops, such as grapes. In grapes, ELONGATED HYPOCOTYL 5 (HY5) and MYBA1 are two critical transcription factors that regulate anthocyanin biosynthesis. Our previous work has shown that B-box protein 44 (VvBBX44) inhibits anthocyanin synthesis and represses expression in grape calli. However, the regulatory mechanism underlying this regulation was unclear. In this study, we found that loss of function resulted in increased anthocyanin accumulation in grapevine callus. VvBBX44 directly represses , which activates . VvMYBA1, but not VvBBX44, directly modulates the expression of grape UDP flavonoid 3--glucosyltransferase (). We demonstrated that VvBBX44 represses the transcriptional activation of and induced by VvMYBA1. However, VvBBX44 and VvMYBA1 did not physically interact in yeast. The application of exogenous anthocyanin stimulated expression in grapevine suspension cells and tobacco leaves. These findings suggest that VvBBX44 and VvMYBA1 form a transcriptional feedback loop to prevent overaccumulation of anthocyanin and reduce metabolic costs. Our work sheds light on the complex regulatory network that controls anthocyanin biosynthesis in grapevine.
花青素对于多年生园艺作物（如葡萄）的品质至关重要。在葡萄中，长胚轴5（HY5）和MYBA1是调控花青素生物合成的两个关键转录因子。我们之前的研究表明，B-box蛋白44（VvBBX44）抑制葡萄愈伤组织中的花青素合成并抑制其表达。然而，这种调控背后的机制尚不清楚。在本研究中，我们发现功能丧失导致葡萄愈伤组织中花青素积累增加。VvBBX44直接抑制激活VvMYBA1的基因，但VvBBX44不直接调节葡萄UDP类黄酮3 - -葡萄糖基转移酶（）的表达。我们证明VvBBX44抑制VvMYBA1诱导的基因和的转录激活。然而，VvBBX44和VvMYBA1在酵母中没有直接相互作用。外源花青素的应用刺激了葡萄悬浮细胞和烟草叶片中的表达。这些发现表明，VvBBX44和VvMYBA1形成转录反馈环，以防止花青素过度积累并降低代谢成本。我们的工作揭示了控制葡萄中花青素生物合成的复杂调控网络。
