Molecular Genetic Analysis of Plant Circadian Rhythms

植物昼夜节律的分子遗传学分析

• 批准号: 0091008
• 负责人: C. Robertson McClung
• 金额: $ 38.5万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0091008&HistoricalAwards=false
• 关键词: Molecular; Genetic; Analysis; Plant; Circadian

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. Circadian rhythms are widespread both within any given organism and among diverse taxa. Genetic and molecular biological studies, primarily in a subset of model organisms, have begun to identify the components of circadian systems. Although plants have provided many examples of rhythmic outputs and our understanding of photoreceptors of circadian input pathways is well-advanced, plants have lagged in the identification of components of the central circadian oscillator. Increased understanding of plant responses to environmental input and to endogenous temporal cues has agricultural importance, in particular because both environmental cues and the circadian clock contribute to the photoperiodic decision to flower. In addition, there is temporal variation in the response to biotic and abiotic stresses, which may prove particularly relevant to attempts to increase agricultural productivity. Arabidopsis mutants affected in clock function, termed circadian timing defective (ctd) and out of phase (oop), have been isolated using the circadian rhythm in resistance/sensitivity to SO2 exposure that results from circadian rhythms in stomatal aperture and gas exchange. For example, oop1 and oop2 represent novel alleles of the photoreceptors PHYTOCHROME B and CRYPTOCHROME 1, respectively. The determination of the molecular mechanisms by which phyBoop1 and cry1oop2 affect circadian phase will afford insight into this integral but poorly understood aspect of circadian rhythmicity. phyBoop1 and cry1oop2 affect both blue and red light signaling in a semi-dominant manner, suggesting that the mutant proteins titrate components common to red and blue light signaling pathways that provide photic input to the clock. The identification of proteins interacting with phyBoop1 and cry1oop2 represents an important goal in the elucidation of this pathway. A second goal is the cloning and the genetic and molecular characterization of a long period mutant, ctd2. Although it has not yet been established that the CTD2 gene encodes a component of a central clock oscillator, the characterization of the ctd2 mutant and the isolation of the CTD2 gene will contribute to the elucidation of the mechanisms of clock function. Potential functions for the CTD2 gene and its product include roles as a component of the central oscillator, as a component of input pathways that provide environmental information to the clock, as well as a component of output pathways that transmit temporal information from the clock to the overtly rhythmic phenomena.

在没有环境时间线索的情况下，以大约24小时的间隔重复出现的节律性生物现象被称为昼夜节律，并且它们的定时由内源性生物钟调节。 昼夜节律在任何给定的生物体和不同的类群中都是普遍存在的。 遗传和分子生物学研究，主要是在一个子集的模式生物，已经开始确定昼夜节律系统的组成部分。 虽然植物提供了许多有节奏的输出的例子，我们的理解光感受器的昼夜节律输入途径是先进的，植物已经落后于中央昼夜节律振荡器的组件的识别。 增加了解植物对环境输入和内源性时间线索的反应具有农业重要性，特别是因为环境线索和生物钟都有助于光周期决定开花。此外，在对生物和非生物压力的反应方面存在时间变化，这可能证明与提高农业生产力的努力特别相关。拟南芥的生物钟功能受到影响的突变体，被称为昼夜节律定时缺陷（ctd）和相位（oop），已被分离出的昼夜节律的电阻/敏感性SO2暴露，结果从昼夜节律的气孔孔径和气体交换。例如，oop 1和oop 2分别代表光感受器光敏色素B和光敏色素1的新等位基因。 phyBoop 1和cry 1 oop 2影响昼夜节律的分子机制的确定将提供洞察到这个不可分割的，但了解甚少的方面的昼夜节律。 phyBoop 1和cry 1 oop 2以半显性的方式影响蓝光和红光信号，这表明突变蛋白滴定了为时钟提供光输入的红光和蓝光信号通路的共同组分。 鉴定与phyBoop 1和cry 1 oop 2相互作用的蛋白质是阐明这一途径的重要目标。 第二个目标是克隆一个长周期突变体ctd 2，并对其进行遗传和分子鉴定。 虽然还没有确定的CTD 2基因编码的一个组成部分的一个中央时钟振荡器，ctd 2突变体的特性和CTD 2基因的分离将有助于阐明时钟功能的机制。CTD 2基因及其产物的潜在功能包括作为中央振荡器的组成部分，作为向时钟提供环境信息的输入途径的组成部分，以及将时间信息从时钟传输到明显节律现象的输出途径的组成部分。