Brassinolide inhibits flavonoid biosynthesis and red-flesh coloration via the MdBEH2.2-MdMYB60 complex in apple
Brassinolide inhibits flavonoid biosynthesis and red-flesh coloration via the MdBEH2.2-MdMYB60 complex in apple
复制标题
DOI：
10.1093/jxb/erab284
复制
发表时间：
2021-06-15
影响因子：
6.9
通讯作者：
Chen, Xuesen
中科院分区：
文献类型：
--
作者：
Wang, Yicheng;Mao, Zuolin;Chen, Xuesen
风味物质含量是衡量果蔬营养价值的重要指标，直接决定了包括苹果在内的许多水果作物的商品性。类黄酮是一类影响植物类黄酮生物合成的甾体激素，但其调控机制尚不清楚。在这项研究中，处理与油菜素（最活跃的BR）和油菜唑（BR生物合成抑制剂），分别降低和增加类黄酮，花青素，原花青素（PA）含量在红肉苹果幼苗和愈伤组织。我们随后证明，BZR（BRI 1-EMS-抑制（BES）/油菜素耐药）家族转录因子，MdBEH2.2，参与BR调节类黄酮的生物合成。具体而言，MdBEH2.2抑制苹果幼苗中黄酮类化合物、花青素和多胺的积累;然而，油菜素唑处理减弱了抑制作用。此外，我们证实BR诱导的MYB TF MdMYB 60与MdBEH2.2相互作用。所得的MdBEH2.2-MdMYB 60复合物进一步增强了MdBEH2.2或MdMYB 60对类黄酮生物合成相关基因转录的抑制作用。这些结果表明油菜素通过MdBEH2.2-MdMYB 60调节模块降低类黄酮含量。我们的研究结果进一步阐明了BR信号调控园艺作物类黄酮生物合成的分子机制。
Flavonoid content, which is an important indicator of the nutritional value of fruits and vegetables, directly determines the marketability of many fruit crops, including apple (Malus domestica). Brassinosteroids (BRs) are steroid hormones that affect flavonoid biosynthesis in plants, but the underlying regulatory mechanism remains unclear. In this study, treatments with brassinolide (the most active BR) and brassinazole (a BR biosynthesis inhibitor) decreased and increased, respectively, the flavonoid, anthocyanin, and proanthocyanidin (PA) content in red-fleshed apple seedlings and calli. We subsequently demonstrated that a BZR (BRI1-EMS-suppressor (BES)/brassinazole-resistant) family transcription factor, MdBEH2.2, participates in BR-regulated flavonoid biosynthesis. Specifically, MdBEH2.2 inhibits the accumulation of flavonoids, anthocyanins, and PAs in apple seedlings; however, brassinazole treatment weakens the inhibitory effect. Additionally, we confirmed that a BR-induced MYB TF, MdMYB60, interacts with MdBEH2.2. The resulting MdBEH2.2-MdMYB60 complex further enhances the inhibitory effect of MdBEH2.2 or MdMYB60 on the transcription of flavonoid biosynthesis-related genes. These results indicate that brassinolide decreases flavonoid content through the MdBEH2.2-MdMYB60 regulatory module. Our findings further clarify the molecular mechanism mediating the regulation of flavonoid biosynthesis by BR signals in horticultural crops.