Calcium-Dependent Protein Kinase and Stress Signal Transduction in Plants

本研究的长期目标是阐明植物中钙依赖性蛋白激酶（CDPKs）介导的胁迫和ABA信号转导的分子机制。该实验计划是基于最近发现的CDPK1和CDPK1a（96%相似）作为特定的正调节因子激活玉米叶片原生质体中多个应激响应启动子。这是首次证明由胁迫或植物胁迫激素触发的细胞内钙信号可以被特定的CDPKs感知并改变植物细胞核中的转录。此外，两种密切相关的蛋白磷酸酶2c （ABI1和AtPP2C）已被证明是CDPK1信号通路的负调控因子。CDPK1和CDPK1a是植物细胞中钙作为第二信使的胁迫信号转导通路的关键调节因子。实验将验证CDPK1在植物生长发育过程中胁迫和ABA应答中发挥重要作用的假设，以及CDPK1直接或间接磷酸化并激活控制胁迫和ABA应答基因的特定转录因子的假设。有五个特定目标：(1)建立CDPK1在植物中的功能，(2)鉴定和分析CDPK1下游的调控成分，(3)确定CDPK1的亚细胞位置和作用，(4)研究PP2C作为负调节因子的作用，(5)分离和表征CDPK1相互作用的蛋白和底物。非生物胁迫，如干旱、寒冷和盐度，对作物产量的影响比所有生物因素的总和还要大。了解胁迫信号转导的分子基础可以为农业改良提供有价值的新工具。CDPK1是本研究的重点，因为它是潜在的主开关之一，可以打开许多下游基因并赋予植物多种逆境耐受性。

The long-term goal of this research is to elucidate the molecular mechanisms underlying stress and abscisic acid (ABA) signal transduction mediated by calcium-dependent protein kinases (CDPKs) in plants. The experimental plan is based on the recent discovery that CDPK1 and CDPK1a (96% similarity) act as specific positive regulators to activate multiple stress responsive promoters in maize leaf protoplasts. This is the first demonstration that intracellular calcium signals triggered by stresses or a plant stress hormone can be perceived by specific CDPKs and alter transcription in the nucleus of plant cells. Furthermore, two closely related protein phosphatase 2Cs (ABI1 and AtPP2C) have been shown to be negative regulators in the CDPK1 signal pathway. It is proposed that CDPK1 and CDPK1a are key regulators in stress signal transduction pathways that use calcium as a second messenger in plant cells. Experiments will test the hypotheses that CDPK1 plays an essential role in stress and ABA responses during plant growth and development, and that CDPK1 directly or indirectly phosphorylates and activates specific transcription factors that control stress and ABA responsive genes. There are five specific objectives: (1) to establish the function of CDPK1 in plants, (2) to identify and analyze regulatory components downstream of CDPK1, (3) to determine CDPK1 subcellular location and action, (4) to investigate the role of PP2C as a negative regulator, and (5) to isolate and characterize CDPK1-interacting proteins and substrates. Abiotic stresses, such as drought, cold, and salinity, reduce crop productivity by an order of magnitude greater than all biotic factors combined. Understanding the molecular basis of stress signal transduction may provide valuable and novel tools for agricultural improvement. CDPK1 is the focus of this research, since it is potentially one of the master switches that can turn on many downstream genes and confer multiple stress tolerance in plants.