Zhang Yanyang, Zhao Yingjia, Hou Xiaoyang, Zhang Chunlin, Wang Ziyi, Zhang Jiaqi, Liu Xianchang, Shi Xinxin, Duan Wanrong, Xiao Kai
State Key Laboratory of North China Crop Improvement and Regulation, Baoding, Hebei, China.
College of Agronomy, Agricultural University of Hebei, Baoding, Hebei, China.
Plant Biotechnol J. 2025 Feb;23(2):352-373. doi: 10.1111/pbi.14501. Epub 2024 Nov 3.
The abscisic acid (ABA) signalling pathway plays a crucial role in plants' response to drought stress. In this study, we aimed to characterize the impact of an ABA signalling module, which consisted of TaPYL9 and its downstream partners in Triticum aestivum, on plant drought adaptation. Our results showed that TaPYL9 protein contains conserved motifs and targets plasma membrane and nucleus after being sorted by the endoplasmic reticulum. In addition, TaPYL9 transcripts in both roots and leaves were significantly upregulated in response to drought stress. We conducted glucuronidase (GUS) histochemical staining analysis for transgenic plants carrying a truncated TaPYL9 promoter, which suggested that cis-elements associate with ABA and drought response, such as ABRE, DRE and recognition sites MYB and MYC, regulating the gene transcription under drought conditions. Using protein interaction assays (i.e., yeast two-hybrid, bimolecular fluorescence complementation (BiFC), co-immunoprecipitation (Co-IP) and in vitro pull-down), we demonstrated interactions between the intermediate segment of TaPYL9, the intermediate segment of TaPP2C6, the N-terminus of TaSnRK2.8 and the C-terminus of the transcription factor TabZIP1 in wheat, indicating the involvement of TaPYL9 in the constitution of an ABA signalling module, namely TaPYL9/TaPP2C6/TaSnRK2.8/TabZIP1. Transgene analysis revealed that TaPYL9, TaSnRK2.8 and TabZIP1 positively regulated drought response, while TaPP2C6 negatively regulated it, and that these genes were closely associated with the regulation of stomata movement, osmolyte accumulation and ROS homeostasis. Electrophoretic mobility shift (EMSA) and transcriptioal activation assays indicated that TabZIP1 interacted promoters of TaP5CS2, TaSLAC1-1 and TaCAT2 and activated transcription of these genes, which regulated proline biosynthesis, stomata movement and ROS scavenging upon drought signalling, respectively. Furthermore, we found that the transcripts of TaPYL9 and stress-responsive genes were positively correlated with yields in wheat cultivars under field drought conditions. Altogether, our findings suggest that the TaPYL9-involved signalling pathway significantly regulates drought response by modulating osmotic stress-associated physiological processes in T. aestivum.
脱落酸（ABA）信号通路在植物对干旱胁迫的响应中起着关键作用。在本研究中，我们旨在阐明由TaPYL9及其在普通小麦中的下游伙伴组成的ABA信号模块对植物干旱适应性的影响。我们的结果表明，TaPYL9蛋白含有保守基序，在内质网分选后靶向质膜和细胞核。此外，根和叶中的TaPYL9转录本在干旱胁迫下均显著上调。我们对携带截短TaPYL9启动子的转基因植物进行了葡糖醛酸糖苷酶（GUS）组织化学染色分析，结果表明与ABA和干旱响应相关的顺式作用元件，如ABRE、DRE以及MYB和MYC识别位点，在干旱条件下调节基因转录。通过蛋白质相互作用分析（即酵母双杂交、双分子荧光互补（BiFC）、免疫共沉淀（Co-IP）和体外下拉实验），我们证明了小麦中TaPYL9的中间片段、TaPP2C6的中间片段、TaSnRK2.8的N端和转录因子TabZIP1的C端之间存在相互作用，表明TaPYL9参与了一个ABA信号模块的构成，即TaPYL9/TaPP2C6/TaSnRK2.8/TabZIP1。转基因分析表明，TaPYL9、TaSnRK2.8和TabZIP1正向调节干旱响应，而TaPP2C6负向调节干旱响应，并且这些基因与气孔运动、渗透溶质积累和活性氧稳态的调节密切相关。电泳迁移率变动（EMSA）和转录激活分析表明，TabZIP1与TaP5CS2、TaSLAC1-1和TaCAT2的启动子相互作用并激活这些基因的转录，它们分别在干旱信号传导时调节脯氨酸生物合成、气孔运动和活性氧清除。此外，我们发现TaPYL9转录本和胁迫响应基因与田间干旱条件下小麦品种的产量呈正相关。总之，我们的研究结果表明，涉及TaPYL9的信号通路通过调节普通小麦中与渗透胁迫相关的生理过程，显著调控干旱响应。
