G protein signaling in the plant response to environmental stress

本研究旨在通过研究调节异源三聚体G蛋白信号和核内Ran-GTP酶的特定蛋白质-蛋白质相互作用来了解植物的逆境耐性。这些调控蛋白的鉴定将是理解植物耐逆性的分子基础和提高植物耐性的重要一步。气候条件的不可预测变化，包括干旱和极端温度，给农业带来了具有挑战性和代价高昂的风险。植物具有广泛的耐逆性遗传变异，在整个农业历史中，一直存在着在逆境条件下提高产量的遗传选择。通过改变气候条件来提高植物耐受性的必要性以及能否成功地实现改善，将取决于对这种耐受性所依据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，这些基因在耐受胁迫的品种中比在敏感品种中诱导得更强。我们已经鉴定了钙结合蛋白Clo3和Clo7，一个盐、干旱和脱落酸诱导的基因Esi2，以及一个与两类G蛋白相互作用的磷脂酶C蛋白，这两个蛋白是异源三聚体蛋白复合体的α亚基和RAN GTP酶。由于这些类型的G蛋白在信号传递、核进出口和细胞分裂中发挥核心作用，我们将工作重点放在这些蛋白上。我们假设，这些蛋白质之间的相互作用通过下调这两类G蛋白的活性来促进细胞对压力的适应。我们已经证明，这些蛋白在拟南芥中的同源蛋白以与小麦蛋白相同的方式相互作用。我们建议利用拟南芥中可用的强大遗传工具来促进我们对控制G蛋白信号转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对环境胁迫耐受性方面的作用。

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.