脱落酸(abscisic acid,ABA)是一种植物体生长发育所必需的植物激素,参与调节种子的萌发和休眠、根生长、气孔关闭、叶片衰老和脱落等重要过程。其功能的发挥主要是通过一系列信号转导来实现的,而其信号转导的第一步取决于与其受体的结合...脱落酸(abscisic acid,ABA)是一种植物体生长发育所必需的植物激素,参与调节种子的萌发和休眠、根生长、气孔关闭、叶片衰老和脱落等重要过程。其功能的发挥主要是通过一系列信号转导来实现的,而其信号转导的第一步取决于与其受体的结合,PYR1类似蛋白9(PYR1-like protein 9,PYL9)作为其主要受体之一,位于ABA信号通路中的上游,在感应ABA信号后,通过抑制2C型蛋白磷酸酶(protein phosphatase 2C,PP2C)活性进而激活蛋白激酶(SNF2-related protein kinase,SnRK2)的活性,促进下游基因表达,开启ABA信号通路,通过影响植物体内脱落酸信号转导、细胞代谢、植物体内生理生化反应等发挥重要作用,来调控植物抗逆境胁迫和生长发育。本文主要从植物生长中ABA的调节作用、与不同激素信号间的相互作用、合成和代谢途径、信号转导组成及作用、脱落酸受体PYL9的结构、功能特征和PYL9在响应逆境胁迫中发挥的重要作用及其存在的问题等方面进行了综述,并对其应用前景进行了展望,以期为今后开展脱落酸受体基因PYL9功能的系统研究及其在植物抗病毒防御反应机理等方面提供理论依据。展开更多
The phytohormone abscisic acid （ABA） regulates many key processes in plants, such as seed germina- tion, seedling growth, and abiotic stress tolerance. In recent years, a minimal set of core components of a major AB...The phytohormone abscisic acid （ABA） regulates many key processes in plants, such as seed germina- tion, seedling growth, and abiotic stress tolerance. In recent years, a minimal set of core components of a major ABA signaling pathway has been discovered. These components include a RCAR/PYR/PYL family of ABA receptors, a group of PP2C phosphatases, and three SnRK2 kinases. However, how the interactions between the receptors and their targets are regulated by other proteins remains largely unknown. In a companion paper published in this issue, we showed that ROP11, a member of the plant- specific Rho-like small GTPase family, negatively regulates multiple ABA responses in Arabidopsis. The current work demonstrated that the constitutively active ROP11 （CA-ROP11） can modulate the RCAR1/PYL9-mediated ABA signaling pathway based on reconstitution assays in Arabidopsis thaliana protoplasts. Furthermore, using luciferase complementation imaging, yeast two-hybrid assays, co- immunoprecipitation assays in Nicotiana benthamiana and bimolecular fluorescence complementation assays, we demonstrated that CA-ROP11 directly interacts with ABI1, a signaling component downstream of RCAR1/PYL9. Finally, we provided biochemical evidence that CA-ROP11 protects ABI1 phosphatase activity from inhibition by RCAR1/PYL9 and thus negatively regulates ABA signaling in plant cells. A model of how ROP11 acts to negatively regulate ABA signaling is presented.展开更多
文摘脱落酸(abscisic acid,ABA)是一种植物体生长发育所必需的植物激素,参与调节种子的萌发和休眠、根生长、气孔关闭、叶片衰老和脱落等重要过程。其功能的发挥主要是通过一系列信号转导来实现的,而其信号转导的第一步取决于与其受体的结合,PYR1类似蛋白9(PYR1-like protein 9,PYL9)作为其主要受体之一,位于ABA信号通路中的上游,在感应ABA信号后,通过抑制2C型蛋白磷酸酶(protein phosphatase 2C,PP2C)活性进而激活蛋白激酶(SNF2-related protein kinase,SnRK2)的活性,促进下游基因表达,开启ABA信号通路,通过影响植物体内脱落酸信号转导、细胞代谢、植物体内生理生化反应等发挥重要作用,来调控植物抗逆境胁迫和生长发育。本文主要从植物生长中ABA的调节作用、与不同激素信号间的相互作用、合成和代谢途径、信号转导组成及作用、脱落酸受体PYL9的结构、功能特征和PYL9在响应逆境胁迫中发挥的重要作用及其存在的问题等方面进行了综述,并对其应用前景进行了展望,以期为今后开展脱落酸受体基因PYL9功能的系统研究及其在植物抗病毒防御反应机理等方面提供理论依据。
基金supported by the 973National Basic Research Program of the Ministry of Science and Technology of China(2009CB119100)the National Natural Science Foundation of China(90717121)
文摘The phytohormone abscisic acid （ABA） regulates many key processes in plants, such as seed germina- tion, seedling growth, and abiotic stress tolerance. In recent years, a minimal set of core components of a major ABA signaling pathway has been discovered. These components include a RCAR/PYR/PYL family of ABA receptors, a group of PP2C phosphatases, and three SnRK2 kinases. However, how the interactions between the receptors and their targets are regulated by other proteins remains largely unknown. In a companion paper published in this issue, we showed that ROP11, a member of the plant- specific Rho-like small GTPase family, negatively regulates multiple ABA responses in Arabidopsis. The current work demonstrated that the constitutively active ROP11 （CA-ROP11） can modulate the RCAR1/PYL9-mediated ABA signaling pathway based on reconstitution assays in Arabidopsis thaliana protoplasts. Furthermore, using luciferase complementation imaging, yeast two-hybrid assays, co- immunoprecipitation assays in Nicotiana benthamiana and bimolecular fluorescence complementation assays, we demonstrated that CA-ROP11 directly interacts with ABI1, a signaling component downstream of RCAR1/PYL9. Finally, we provided biochemical evidence that CA-ROP11 protects ABI1 phosphatase activity from inhibition by RCAR1/PYL9 and thus negatively regulates ABA signaling in plant cells. A model of how ROP11 acts to negatively regulate ABA signaling is presented.
