Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
College of Environmental Sciences, Sichuan Agricultural University, Chengdu, 611130, Sichuan, China.
New Phytol. 2017 Nov;216(3):814-828. doi: 10.1111/nph.14692. Epub 2017 Jul 19.
Little is known about the molecular mechanism of the R2R3-MYB transcriptional repressors involved in plant phenylpropanoid metabolism. Here, we describe one R2R3-type MYB repressor, FtMYB11 from Fagopyrum tataricum. It contains the SID-like motif GGDFNFDL and it is regulated by both the importin protein 'Sensitive to ABA and Drought 2' (SAD2) and the jasmonates signalling cascade repressor JAZ protein. Yeast two hybrid and bimolecular fluorescence complementation assays demonstrated that FtMYB11 interacts with SAD2 and FtJAZ1. Protoplast transactivation assays demonstrated that FtMYB11 acts synergistically with FtSAD2 or FtJAZ1 and directly represses its target genes via the MYB-core element AATAGTT. Changing the Asp122 residue to Asn in the SID-like motif results in cytoplasmic localization of FtMYB11 because of loss of interaction with SAD2, while changing the Asp126 residue to Asn results in the loss of interaction with FtJAZ1. Overexpression of FtMYB11or FtMYB11 in F. tataricum hairy roots resulted in reduced accumulation of rutin, while overexpression of FtMYB11 in hairy roots did not lead to such a change. The results indicate that FtMYB11 acts as a regulator via interacting with FtSAD2 or FtJAZ1 to repress phenylpropanoid biosynthesis, and this repression depends on two conserved Asp residues of its SID-like motif.
关于参与植物苯丙烷代谢的 R2R3-MYB 转录阻遏物的分子机制知之甚少。在这里，我们描述了荞麦中的一个 R2R3 型 MYB 阻遏物 FtMYB11。它包含 SID 样基序 GGDFNFDL，受导入蛋白'Sensitive to ABA and Drought 2'（SAD2）和茉莉酸信号级联阻遏蛋白 JAZ 蛋白的调控。酵母双杂交和双分子荧光互补测定表明，FtMYB11 与 SAD2 和 FtJAZ1 相互作用。原生质体转录激活测定表明，FtMYB11 通过 MYB 核心元件 AATAGTT 与 FtSAD2 或 FtJAZ1 协同作用并直接抑制其靶基因。在 SID 样基序中将 Asp122 残基突变为 Asn 会导致 FtMYB11 发生细胞质定位，因为与 SAD2 的相互作用丧失，而将 Asp126 残基突变为 Asn 会导致与 FtJAZ1 的相互作用丧失。在荞麦毛状根中过表达 FtMYB11 或 FtMYB11 会导致芦丁积累减少，而过表达 FtMYB11 在毛状根中不会导致这种变化。结果表明，FtMYB11 通过与 FtSAD2 或 FtJAZ1 相互作用作为调节剂发挥作用，以抑制苯丙烷生物合成，这种抑制依赖于其 SID 样基序中的两个保守的 Asp 残基。
