NASA/NSF Collaborative Research: Blue-Light Signal Transduction in Arabidopsis Seedlings: A Multidisciplinary Study

NASA/NSF 合作研究：拟南芥幼苗中的蓝光信号转导：一项多学科研究

• 批准号: 9416016
• 负责人: Edgar Spalding
• 金额: $ 52.3万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-09-01 至 1999-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9416016&HistoricalAwards=false
• 关键词: NASA; NSF; Collaborative; Research; Blue

MCB 9416016 Spalding Blue light induces a large, transient membrane depolarization a few seconds before a large reduction in the rate of stem elongation in etiolated seedlings. The molecular mechanism that mediates this depolarization is unknown although there is evidence that the plasma membrane H+-ATPase is inhibited and anion channels are activated. The proposed work is an electrophysiological investigation of the changes in ion transport at the plasma membrane that participate in the transduction of blue light into growth inhibition. The growing cells of etiolated Arabidopsis hypocotyls will be studied with the patch clamp technique to characterize the ion channels that undergo a change in activity after a pulse of blue light. The participation of anion-selective channels will be given particular attention. The effect of blue light on the activity of the H+-ATPase will be determined both electrophysiologically and biochemically. Mutants in Arabidopsis that do not display blue-light inhibited growth will be studied in addition to the wild-type. Well defined energies and wavelengths of blue light will be used to construct fluence rate response curves for the magnitudes and kinetics of the electrical responses of the different genotypes. At least one double mutant, blu1 hy4, will be constructed and similarly studied. The results will demonstrate if and how the genetic lesions affect these early blue-light induced changes in membrane transport. This combination of electrophysiology, biochemistry and genetics is expected to reveal some important features of a transduction chain that links blue- light receptors to a growth control mechanism. %%% Seedlings grown in the dark undergo a suite of developmental changes upon illumination, resulting in a green plant that is competent to perform photosynthesis. One aspects of this important developmental process is the inhibition of stem elongation by bright blue light . A pulse of blue light inhibits stem growth after a few seconds. This means a receptor that absorbs blue light is closely connected to a mechanism that controls the growth rate of the stem. The events that occur between the activation of the blue light receptor and the beginning of the growth response are said to transduce the blue light into growth inhibition. Collectively these events are called a transduction chain. All that is currently known about this transduction chain is that the transport across the cells outer membrane of ions is altered just before the growth rate slows. The proposed work is focused on elucidating at the molecular level the details of how blue light alters the activities of ion pumps and channels in the membrane and how this then affects the seedlings growth rate . The electrophysiological technique of patch clamping will be used for many of the experiments, all of which will be performed on the Arabidopsis plant In addition, genetic techniques to take advantage of the existence of mutants in Arabidopsis which do not display blue light inhibited growth will be sued, as will some biochemical techniques. Taken together, these experiments will reveal certain aspects of how light controls plant growth and development and how ion channels and pumps participate in the transduction of environmental signals. ***

在黄化幼苗茎伸长速率大幅降低之前，MCB 9416016蓝光在几秒钟内诱导了一个大的、瞬时的膜去极化。尽管有证据表明质膜H+-ATPase被抑制而阴离子通道被激活，但介导这种去极化的分子机制尚不清楚。这项拟议的工作是对参与蓝光转化为生长抑制的质膜离子运输变化的电生理学研究。将用膜片钳技术研究黄化拟南芥下胚轴的生长细胞，以表征在蓝光脉冲后经历活动变化的离子通道。对阴离子选择性通道的参与将给予特别关注。蓝光对H+-ATPase活性的影响将通过电生理和生物化学来确定。除了野生型外，还将研究拟南芥中不表现出蓝光抑制生长的突变体。明确定义的蓝光能量和波长将被用来构建不同基因型电响应的大小和动力学的注量率响应曲线。将构建至少一个双突变体，Blu1hy4，并进行类似的研究。结果将展示遗传损伤是否以及如何影响这些早期蓝光诱导的膜运输变化。这种电生理学、生物化学和遗传学的结合有望揭示将蓝光受体与生长控制机制联系起来的转导链的一些重要特征。在黑暗中生长的幼苗在光照下会经历一系列的发育变化，从而产生能够进行光合作用的绿色植物。这一重要的发育过程的一个方面是明亮的蓝光对茎伸长的抑制。几秒钟后，蓝光脉冲会抑制茎的生长。这意味着，吸收蓝光的受体与控制茎生长速度的机制密切相关。在蓝光感受器激活和生长反应开始之间发生的事件被认为是将蓝光转化为生长抑制。这些事件统称为转导链。目前对这种转导链的所有了解是，离子在细胞外膜上的运输在生长速度放缓之前发生了变化。拟议的工作重点是在分子水平上阐明蓝光如何改变膜中离子泵和离子通道的活动，以及这如何影响幼苗的生长速度。膜片钳的电生理技术将用于许多实验，所有这些实验都将在拟南芥植物上进行，此外，还将利用拟南芥中不显示蓝光抑制生长的突变体的存在，以及一些生化技术。综上所述，这些实验将揭示光如何控制植物的生长和发育，以及离子通道和泵如何参与环境信号传递的某些方面。***