Molecular Genetics Analysis of Plant Circadian Rhythms

植物昼夜节律的分子遗传学分析

• 批准号: 9723482
• 负责人: C. Robertson McClung
• 金额: $ 20.5万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9723482&HistoricalAwards=false
• 关键词: Molecular; Genetics; Analysis; Plant; Circadian

McClung 9723482 The molecular basis by which time information is generated in plants will be investigated in the model plant, Arabidopsis thaliana. The molecular clock regulates overt rhythms in gas exchange, leaf movement and gene expression. Arabidopsis mutants affected in clock function have been isolated using the circadian rhythm in resistance/sensitivity to SO2 exposure that results from the circadian rhythms in stomatal aperture and gas exchange. If 65 mutants, 3 flower significantly earlier than wild type and 30 flower significantly later. Six of 21 tested also display a long hypocotyl phenotype. Efforts will be concentrated on one mutant, Circadian Timing Defective 1 (ctd1), which flowers later than wild type, but retains photoperiod sensitivity. The mutation is inherited as recessive nuclear gene. Ctd1 shows a short period in oscillations in mRNA abundance for four genes, the implication being that ctd1 affects a process common to expression of all four genes and thus defines a component of a common oscillator or of a common input or output pathway. Ctd1 will be characterized both phenotypically and genetically followed by cloning and characterization of the gene. Other ctd mutants with altered clock properties will continue to be characterized and the search for new mutants will also be continued. Rhythmic biological phenomena which recur at approximately 24 hour intervals in the absence of environmental time cues are termed circadian rhythms. Their timing is regulated by an endogenous biological clock. Such rhythms are ubiquitous and have been described in great detail at a phenomenological level. Plants provide excellent systems for study of circadian rhythmicity because plants are robustly rhythmic and exquisitely sensitive to environmental input, probably reflecting both their sessile growth form and their dependence on their immediate environment for nutrition and energy. Increased understanding of plant responses to environmental input and to endogenous temporal cues ha s agricultural importance, in particular, because both environmental cues and the circadian clock contribute to the photoperiodic decision to flower. A genetic and molecular biological analysis of mutants identified by a novel screen will be done in Arabidopsis thaliana, the model plant.

植物中产生时间信息的分子基础将在模式植物拟南芥中进行研究。分子钟调节气体交换、叶片运动和基因表达的明显节奏。利用由气孔孔径和气体交换的昼夜节律导致的SO2暴露抗性/敏感性的昼夜节律，分离出受时钟功能影响的拟南芥突变体。65个突变体中，3个明显早于野生型开花，30个明显晚于野生型开花。21个测试中有6个也显示长下胚轴表型。努力将集中在一个突变体上，昼夜节律时序缺陷1 (ctd1)，它比野生型晚开花，但保留光周期敏感性。该突变以隐性核基因的形式遗传。Ctd1显示四种基因的mRNA丰度振荡周期较短，这意味着Ctd1影响所有四种基因表达的共同过程，从而定义了共同振荡器或共同输入或输出途径的组成部分。Ctd1将在表型和遗传学上进行表征，随后进行基因的克隆和表征。其他具有改变时钟特性的ctd突变体将继续被表征，寻找新的突变体也将继续进行。在没有环境时间线索的情况下，每隔大约24小时发生一次的节律性生物现象被称为昼夜节律。它们的时间是由内源性生物钟调节的。这种节奏无处不在，并在现象学层面上得到了非常详细的描述。植物为研究昼夜节律性提供了极好的系统，因为植物具有强大的节律性，对环境输入非常敏感，这可能反映了它们的无根生长形式和它们对直接环境的营养和能量的依赖。增加对植物对环境输入和内源性时间线索的反应的理解对农业具有重要意义，特别是因为环境线索和昼夜节律钟都有助于光周期决定开花。拟南芥（Arabidopsis thaliana）是一种模式植物，将对一种新型筛选方法鉴定出的突变体进行遗传和分子生物学分析。