Genetic & Molecular Analysis of the Regulation of Tropic Growth in Arabidopsis thaliana

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• 批准号: 0077312
• 负责人: Emmanuel Liscum
• 金额: $ 36.09万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0077312&HistoricalAwards=false
• 关键词: Genetic; & Molecular; Analysis; Regulation

The goal of this research is to understand how plants perceive changes in their environment, transduce that information and ultimately alter growth and/or development to elicit proper adaptive differential growth responses. The phototropic response is being used as a model system to study light-driven signal transduction and regulation of cellular growth. Several loci, previously identified via mutation, have been characterized as necessary for normal phototropism in Arabidopsis thaliana L. Heynh. The NPH4 locus (nonphototropic hypocotyl 4) is important not only for phototropism, but also for several additional differential growth responses, including gravitropism, apical hook maintenance and abaxial/adaxial leaf blade expansion. The NPH4 gene has been cloned and found to encode the auxin-regulated transcriptional activator, ARF7, suggesting that auxin-dependent changes in gene transcription are prerequisite for proper organ bending responses. However, NPH4/ARF7 is not the sole regulator of these changes since the phenotypes of nph4-null mutants are conditional. For example, phytochrome A (phy A) activation, which leads to enhancement of blue light-induced phototropism in wild-type, results in restoration of a partial phototropic response in nph4 seedlings. Specific aims are 1) To identify genes that are transcriptionally regulated by NPH4/ARF7 and necessary for tropic reponsiveness and 2) To characterize components of the phytochrome A-dependent modulatory pathway(s) leading to phototropic enhancement. Because of their sessile nature, plants have evolved movement strategies that involve organ bending in order to respond to changes in their environment. Dramatic, rapid and reversible changes in morphology can result from differential growth- or unequal cellular growth in one position of an organ relative to an opposing position. Continued study of the nph4 mutants and in planta function of the NPH4/ARF7 protein will provide significant new insights into the basic cellular mechanisms leading to tropic responses, as well as the interactions between multiple signal-response pathways that modulate those tropic responses.

这项研究的目标是了解植物如何感知环境的变化，识别这些信息并最终改变生长和/或发育，以引起适当的适应性差异生长反应。 向光反应是研究光驱动信号转导和细胞生长调控的一个模型系统。 先前通过突变鉴定的几个基因座已被鉴定为拟南芥正常向光性所必需。嘿 NPH 4基因座（nonphototropic下胚轴4）是重要的，不仅为向光性，但也为几个额外的差异生长反应，包括向重力性，顶钩维护和远轴/近轴叶片膨胀。 NPH 4基因已被克隆，并发现编码生长素调节的转录激活因子ARF 7，这表明生长素依赖的基因转录变化是适当的器官弯曲反应的先决条件。 然而，NPH 4/ARF 7不是这些变化的唯一调节因子，因为nph 4缺失突变体的表型是有条件的。 例如，光敏色素A（phytochrome A，phy A）激活，其导致野生型中蓝光诱导的向光性的增强，导致nph 4幼苗中部分向光性响应的恢复。 具体目标是：1）鉴定受NPH 4/ARF 7转录调控且对向光性反应必需的基因; 2）表征导致向光性增强的光敏色素A依赖性调节途径的组分。由于它们的无柄性质，植物已经进化出涉及器官弯曲的运动策略，以应对环境的变化。 形态学的显著、快速和可逆变化可能是由于差异生长-或器官的一个位置相对于相对位置的不相等细胞生长。 对nph 4突变体和NPH 4/ARF 7蛋白在植物中的功能的继续研究将为导致嗜性反应的基本细胞机制以及调节这些嗜性反应的多个信号-反应途径之间的相互作用提供重要的新见解。