State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan Provincial Key Laboratory of Plant Functional Genomics and Developmental Regulation, College of Biology, Hunan University, Changsha 410082, China.
Shenzhen Research Institute of Hunan University, Shenzhen 518055, China.
Int J Mol Sci. 2022 Oct 29;23(21):13194. doi: 10.3390/ijms232113194.
Jasmonates (JAs) are the most effective inducers for the biosynthesis of various secondary metabolites. Currently, jasmonate ZIM domain (JAZ) and its interactors, such as MYC2, constitute the main JA signal transduction cascade, and such a cascade fails to directly regulate all the taxol biosynthesis genes, especially the rate-limit gene, DBAT. Another JA signaling branch, JAV and WRKY, would probably fill the gap. Here, TcJAV3 was the closest VQ-motif-containing protein in Taxus chinensis to AtJAV1. Although TcJAV3 was overexpressed in AtJAV1 knockdown mutant, JAVRi17, the enhanced disease resistance to Botrytis cinerea caused by silencing AtJAV1 was completely recovered. The results indicated that TcJAV3 indeed transduced JA signal as AtJAV1. Subsequently, TcWRKY26 was screened out to physically interact with TcJAV3 by using a yeast two-hybrid system. Furthermore, bimolecular fluorescence complementation and luciferase complementary imaging also confirmed that TcJAV3 and TcWRKY26 could form a protein complex in vivo. Our previous reports showed that transient TcWRKY26 overexpression could remarkably increase DBAT expression. Yeast one-hybrid and luciferase activity assays revealed that TcWRKY26 could directly bind with the wa-box of the DBAT promoter to activate downstream reporter genes. All of these results indicated that TcWRKY26 acts as a direct regulator of DBAT, and the TcJAV3−TcWRKY26 complex is actually another JA signal transduction mode that effectively regulates taxol biosynthesis in Taxus. Our results revealed that JAV−WRKY complexes directly regulated DBAT gene in response to JA stimuli, providing a novel model for JA-regulated secondary metabolism. Moreover, JAV could also transduce JA signal and function non-redundantly with JAZ during the regulation of secondary metabolisms.
茉莉酸（JAs）是诱导各种次生代谢产物生物合成最有效的物质。目前，茉莉酸 ZIM 结构域（JAZ）及其相互作用因子，如 MYC2，构成了主要的 JA 信号转导级联，而该级联无法直接调控所有紫杉醇生物合成基因，特别是限速基因 DBAT。另一个 JA 信号分支，JAV 和 WRKY，可能会填补这一空白。在这里，TcJAV3 是 Taxus chinensis 中与 AtJAV1 最接近的含有 VQ 基序的蛋白。虽然 TcJAV3 在 AtJAV1 敲低突变体 JAVRi17 中过表达，但沉默 AtJAV1 引起的对灰葡萄孢的增强抗病性完全恢复。结果表明，TcJAV3 确实像 AtJAV1 一样转导 JA 信号。随后，通过酵母双杂交系统筛选出与 TcJAV3 物理相互作用的 TcWRKY26。此外，双分子荧光互补和荧光素酶互补成像也证实 TcJAV3 和 TcWRKY26 可以在体内形成蛋白质复合物。我们之前的报告表明，瞬时过表达 TcWRKY26 可以显著增加 DBAT 的表达。酵母单杂交和荧光素酶活性测定表明，TcWRKY26 可以直接与 DBAT 启动子的 wa-box 结合，激活下游报告基因。所有这些结果表明，TcWRKY26 是 DBAT 的直接调控因子，而 TcJAV3−TcWRKY26 复合物实际上是另一种有效调节 Taxus 中紫杉醇生物合成的 JA 信号转导模式。我们的结果表明，JAV−WRKY 复合物直接响应 JA 刺激调节 DBAT 基因，为 JA 调节次生代谢提供了一个新的模型。此外，JAV 在调节次生代谢物时也可以转导 JA 信号，并与 JAZ 发挥非冗余功能。
