Huang Yan, Yang Rongqian, Luo Huiling, Yuan Yuan, Diao Zhihong, Li Junhao, Gong Shihe, Yu Guozhi, Yao Huipeng, Zhang Huaiyu, Cai Yi
College of Life Sciences, Sichuan Agricultural University, Ya'an 625000, China.
Plants (Basel). 2023 Jul 21;12(14):2716. doi: 10.3390/plants12142716.
Reversible phosphorylation of proteins is a ubiquitous regulatory mechanism in vivo that can respond to external changes, and plays an extremely important role in cell signal transduction. Protein phosphatase 2C is the largest protein phosphatase family in higher plants. Recently, it has been found that some clade A members can negatively regulate ABA signaling pathways. However, the functions of several subgroups of PP2C other than clade A have not been reported, and whether other members of the PP2C family also participate in the regulation of ABA signaling pathways remains to be studied. In this study, based on the previous screening and identification work of PP2C involved in the ABA pathway, the clade F member PIA1 encoding a gene of the family, which was down-regulated after ABA treatment during the screening, was selected as the target. Overexpression of significantly down-regulated the expression of ABA marker gene in protoplasts, and ABA-responsive elements have been found in the cis-regulatory elements of by promoter analysis. When compared to Col-0, transgenic plants overexpressing were less sensitive to ABA, whereas showed the opposite trait in seed germination, root growth, and stomatal opening experiments. Under drought stress, SOD, POD, CAT, and APX activities of overexpression lines were lower than Col-0 and , while the content of HO was higher, leading to its lowest survival rate in test plants, which were consistent with the significant inhibition of the expression of ABA-dependent stress-responsive genes , , , and in the transgenic background after ABA treatment. Using yeast two-hybrid and luciferase complementation assays, PIA1 was found to interact with multiple ABA key signaling elements, including 2 RCARs and 6 SnRK2s. Our results indicate that may reduce plant drought tolerance by functioning as a common negative regulator involved in ABA signaling pathway.
蛋白质的可逆磷酸化是体内一种普遍存在的调节机制，能够响应外部变化，并在细胞信号转导中发挥极其重要的作用。蛋白磷酸酶2C是高等植物中最大的蛋白磷酸酶家族。最近发现，一些A类成员可负调控ABA信号通路。然而，除A类外的其他几个PP2C亚组的功能尚未见报道，PP2C家族的其他成员是否也参与ABA信号通路的调控仍有待研究。在本研究中，基于先前对参与ABA途径的PP2C的筛选和鉴定工作，选择了该家族中一个基因的F类成员PIA1作为研究对象，该成员在筛选过程中经ABA处理后表达下调。PIA1的过表达显著下调了原生质体中ABA标记基因的表达，并且通过启动子分析在PIA1的顺式调控元件中发现了ABA响应元件。与Col-0相比，过表达PIA1的转基因植物对ABA的敏感性较低，而在种子萌发、根生长和气孔开放实验中PIA1表现出相反的性状。在干旱胁迫下，过表达PIA1的株系的超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性低于Col-0和PIA1缺失株系，而过氧化氢（H₂O₂）含量较高，导致其在受试植物中的存活率最低，这与ABA处理后PIA1转基因背景下ABA依赖的胁迫响应基因RD29A、RD29B、COR47和KIN1的表达受到显著抑制一致。通过酵母双杂交和荧光素酶互补试验发现，PIA1与多个ABA关键信号元件相互作用，包括2个RCARs和6个SnRK2s。我们的结果表明，PIA1可能作为ABA信号通路中的一个共同负调控因子发挥作用，从而降低植物的耐旱性。
