G protein signaling in the plant response to environmental stress

本研究计划旨在通过表征异源三聚体G蛋白信号传导调控和核RAN-GTPase调控中的特定蛋白-蛋白相互作用来了解植物的抗逆性。这些调控蛋白的鉴定将是了解植物抗逆性的分子基础和提高植物抗逆性的重要一步。气候条件的不可预测变化，包括干旱和极端温度，给农业带来了挑战和代价高昂的风险。植物具有广泛的抗逆性遗传变异，在整个农业历史中，在逆境条件下提高产量的遗传选择一直存在。由于气候条件的变化而增加的提高植物耐受性的需要以及在实现改善方面的成功将取决于对支撑这种耐受性的生物学机制的理解。我的实验室已经在面包小麦（Triticum aestivum）中发现了大量的调控基因，这些基因在耐受性基因型中比在敏感基因型中更容易受到胁迫条件的诱导。我们已经鉴定了钙结合蛋白Clo3和Clo7，盐、干旱和ABA诱导基因Esi2，以及磷脂酶C蛋白，这些蛋白与两类G蛋白，异三聚体蛋白复合物的α亚基和RAN GTPase相互作用。由于这类G蛋白在信号传导、核输入和输出以及细胞分裂中起着核心作用，因此我们将工作重点放在了这些蛋白上。我们假设这些蛋白-蛋白相互作用通过下调这两类G蛋白的活性来促进细胞对应激的适应。我们已经证明，拟南芥中这些蛋白的同源物与小麦蛋白的相互作用方式相同。我们建议利用拟南芥中强大的遗传工具来推进我们对控制G蛋白信号传导的基本遗传和分子机制的理解，并研究这些蛋白质-蛋白质相互作用在提高植物环境胁迫耐受性中的作用。

This research proposal is directed toward understanding of stress tolerance in plants through the characterization of specific protein-protein interactions in the regulation heterotrimeric G protein signaling and the regulation of the nuclear RAN-GTPase. The characterization of these regulatory proteins will be an important step forward in understanding the molecular basis of stress tolerance and improving the tolerance of plants. Unpredictable changes in climatic conditions, including drought and extreme temperatures pose challenging and costly risks to agriculture. Plants have a wide genetic variation for stress tolerance and throughout the history of agriculture there as been genetic selection for improved yield under stress conditions. The need to improve tolerance in plants augmented by changing climatic conditions and the success in achieving improvements will be dependent on understanding the biological mechanisms underpinning this tolerance. My laboratory has identified a large number of regulatory genes in bread wheat (Triticum aestivum) that are more strongly induced by stress conditions in tolerant genotypes than in sensitive genotypes. We have identified calcium binding proteins Clo3 and Clo7, a salt, drought and ABA induced gene Esi2, and a phospholipase C proteins that interact with two classes G proteins, the alpha subunit of the heterotrimeric protein complex and the RAN GTPase. Because these classes of G proteins play central roles in signaling, nuclear import and export and in cell division we have focused our work on these proteins. We hypothesize that these protein-protein interactions contribute to the cell's adaptation to stress by down-regulating the activity of these two classes of G proteins. We have shown that the homologs of these proteins in Arabidopsis interact in the same manner as the wheat proteins. We propose to use the powerful genetic tools available in Arabidopsis to advance our understanding of the basic genetic and molecular mechanisms that control G proteins signaling and to investigate the role of these protein-protein interactions in improving environmental stress tolerance in plants.