Wang Zhaoqiang, Wei Xiangyan, Wang Yiqiao, Sun Mengting, Zhao Peiyu, Wang Qiannan, Yang Bo, Li Jing, Jiang Yuan-Qing
State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, 712100, China.
State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, 712100, China.
Plant Physiol Biochem. 2023 Jan;194:134-145. doi: 10.1016/j.plaphy.2022.11.012. Epub 2022 Nov 13.
The gaseous phytohormone ethylene participates in a lot of physiological processes in plants. 1-aminocyclopropane-1-carboxylic acid (ACC) synthase (ACS, EC 4.4.1.14) and the ACC oxidase (ACO, EC 1.14.17.4) are key enzymes in ethylene biosynthesis. However, how ACSs and ACOs are regulated at the transcriptional level is largely unknown. In the present study, we showed that an Arabidopsis (Arabidopsis thaliana) WRKY-type transcription factor (TF), WRKY29 positively regulated the expression of ACS5, ACS6, ACS8, ACS11 and ACO5 genes and thus promoted basal ethylene production. WRKY29 protein was localized in nuclei and was a transcriptional activator. Overexpression of WRKY29 caused pleiotropic effect on plant growth, development and showed obvious response even without ACC treatment. Inducible overexpression of WRKY29 also reduced primary root elongation and lateral root growth. A triple response assay of overexpression and mutant seedlings of WRKY29 showed that overexpression seedlings had shorter hypocotyls than the transgenic GFP (Green Fluorescence Protein) control, while mutants had no difference from wild-type. A qRT-PCR assay demonstrated that expression of multiple ACSs and ACO5 was up-regulated in WRKY29 overexpression plants. A transactivation assay through dual luciferase reporter system confirmed the regulation of promoters of ACS5, ACS6, ACS8, ACS11 and ACO5 by WRKY29. Both in vivo chromatin immunoprecipitation (ChIP)- quantitative PCR and in vitro electrophoretic mobility shift assay (EMSA) revealed that WRKY29 directly bound to the promoter regions of its target genes. Taken together, these results suggest that WRKY29 is a novel TF positively regulating ethylene production by modulating the expression of ACS and ACO genes.
气态植物激素乙烯参与植物的许多生理过程。1-氨基环丙烷-1-羧酸（ACC）合酶（ACS，EC 4.4.1.14）和ACC氧化酶（ACO，EC 1.14.17.4）是乙烯生物合成中的关键酶。然而，ACSS和ACOS在转录水平上如何被调控在很大程度上尚不清楚。在本研究中，我们发现拟南芥（Arabidopsis thaliana）WRKY型转录因子（TF）WRKY29正向调控ACS5、ACS6、ACS8、ACS11和ACO5基因的表达，从而促进基础乙烯产生。WRKY29蛋白定位于细胞核，是一种转录激活因子。WRKY29的过表达对植物生长、发育产生多效性影响，甚至在没有ACC处理的情况下也表现出明显的反应。WRKY29的诱导型过表达也降低了主根伸长和侧根生长。WRKY29过表达和突变体幼苗的三重反应试验表明，过表达幼苗的下胚轴比转基因绿色荧光蛋白（GFP）对照短，而突变体与野生型无差异。qRT-PCR试验表明，多个ACSS和ACO5在WRKY29过表达植物中的表达上调。通过双荧光素酶报告系统的反式激活试验证实了WRKY29对ACS5、ACS6、ACS8、ACS11和ACO5启动子的调控。体内染色质免疫沉淀（ChIP）-定量PCR和体外电泳迁移率变动分析（EMSA）均表明WRKY29直接结合其靶基因的启动子区域。综上所述，这些结果表明WRKY29是一种通过调节ACS和ACO基因表达正向调控乙烯产生的新型TF。
