Transduction of Calcium Signals in Guard Cells

伊利诺伊大学的Raymond Zielinski博士获得了一项资助，以阐明钙调节气孔保护细胞功能的机制。他的研究将采用分子、细胞和遗传方法相结合的方法来可视化控制活细胞气孔功能的调节分子的活动。钙离子浓度的变化是调控气孔关闭和限制叶片水分流失的早期重要信号。然而，关于钙信号如何促进气孔关闭的机制知之甚少。推动本研究的主要假设是，气孔关闭所需的钙信号中的信息是由钙受体蛋白钙调蛋白的激活和分布的特征性变化转导的。为了验证这一假设，他将使用转基因植物中表达的新型荧光指示剂来测量钙调素激活的变化，从而使钙调素激活在活细胞中可视化。他的项目将采用模式植物拟南芥（Arabidopsis thaliana），利用基因组表征和测序工作所提供的大量遗传资源。气孔是由在叶片表面形成气孔的保护细胞对所定义的结构，这些气孔根据植物所经历的大量环境条件而打开或关闭。气孔的打开是为了让二氧化碳进入叶片进行光合作用，同时也限制了水分的蒸发损失，因为蒸发会导致植物枯萎和死亡。平衡这些相互冲突的活动在决定自然生态系统中的植物生长和农业中的作物植物生产力方面起着重要作用。定义气孔保护细胞如何调节二氧化碳吸收和水分流失之间的关键平衡，对于理解影响农业产量的主要决定因素及其如何受到全球气候变化的影响至关重要。

A grant has been awarded to Dr. Raymond Zielinski of the University of Illinois to elucidate mechanisms regulating the function of stomatal guard cells by calcium.. His study will employ a combination of molecular, cellular and genetic approaches to visualize the activity of regulatory molecules that control stomatal function in living cells. Changes in the concentration of calcium ions are an early, important signal in regulating stomatal closure and restricting water loss from leaves. However, little is known about the mechanisms by which calcium signals are communicated to facilitate stomatal closure. The primary hypothesis driving this research is that the information in calcium signals required for stomatal closure is transduced by characteristic changes in the activation and distribution of the calcium receptor protein calmodulin. To test this hypothesis, he will measure changes in calmodulin activation using novel fluorescent indicators expressed in transgenic plants that allow calmodulin activation to be visualized in live cells. His project will employ the model plant, Arabidopsis thaliana, to take advantage of the tremendous number of genetic resources facilitated by the genomic characterization and sequencing efforts.Stomata are structures defined by pairs of guard cells that form pores on leaf surfaces, which open or close in response to the vast array of environmental conditions experienced by plants. Stomatal pores open to allow the entry of CO2 into leaves for photosynthesis while at the same time restricting water loss by evaporation that can lead to wilting and plant death. Balancing these conflicting activities plays a major role in determining plant growth in natural ecosystems and crop plant productivity in agriculture. Defining how stomatal guard cells regulate the critical balance between CO2 uptake and water loss is key to understanding the major determinant influencing agricultural yields and how it may be affected by global climate change.