Molecular Genetic Analysis of Plant Circadian Rhythms

在没有环境时间线索的情况下，以大约24小时间隔重复的节律性生物现象被称为昼夜节律，并且它们的时间由内源性生物钟调节。在任何生物系统中，昼夜节律的分子基础都不清楚。我们的研究将继续在拟南芥的这种节奏，1）调查个体发育的昼夜节律钟和光的作用，在诱导和定相的昼夜节律在幼苗。2)利用基于气孔孔径昼夜节律对二氧化硫暴露的昼夜抗性的筛选，鉴定和分析具有改变的时钟特性（具体地，改变的周期长度）的突变体; 3）分析RCA转录的昼夜调节，RCA转录是参与碳同化的基因。 这些实验旨在阐明生物钟产生时间信息并用于调节植物基因表达的分子基础。生物钟调节许多拟南芥基因的表达，包括涉及光捕获、碳同化、光呼吸和氮同化的基因。生物钟与光的相互作用表明，任何完整的理解植物对环境刺激的反应，如光水平和光暗制度，必须包括对植物的内源能力的理解来测量时间。 ***

McClung 9316662 Rhythmic biological phenomena which recur at approximately 24 hour intervals in the absence of environmental time cues are termed circadian rhythms, and their timing is regulated by an endogenous biological clock. The molecular basis of circadian rhythmicity is not understood in any biological system. Our study of such rhythms in Arabidopsis thalania will be continued by, 1) Investigating the ontogeny of the circadian clock and of the role of light in the induction and phasing of circadian rhythmicity in seedlings. 2) Identification and analysis of mutants with altered clock properties (specifically, altered period length) using a screen based on the circadian resistance to sulfur dioxide exposure conferred by the circadian rhythm in stomatal aperture and 3) The analysis of the circadian regulation of RCA transcription, a gene involved in carbon assimilation. %%% The experiments to be done are designed to elucidate the molecular basis by which time information is generated by the biological clock and used to regulate plant gene expression. The circadian clock regulates the expression of a number of Arabidopsis genes, including genes involved in light harvesting, in carbon assimilation, in photorespiration and in nitrogen assimilation. The interaction between the circadian clock and light indicate that any complete understanding of plant response to environmental stimuli, such as light level and light-dark regimen, must include an understanding for the endogenous capacity of plants to measure time. ***