Gibberellins and Floral Induction in Arabidopsis

从营养生长到开花的转变既受环境因素的控制，也受内源因素的控制。了解这些信号在哪里以及如何整合是理解为什么相似的环境或内源信号可以在不同的植物中引发相反的开花反应的先决条件。例如，虽然植物激素赤霉素通常会诱导拟南芥等莲座状植物开花，但它会抑制其他几种植物的开花。类似地，拟南芥在较长的日间开花比在较短的日间开花快，而其他植物在较短的日间优先甚至排他性地开花。魏格尔博士提出了互补的生化、生理、分子和遗传方法来确定赤霉素是如何诱导拟南芥开花的。他已经证明，在拟南芥中，开花信号会聚在花特征基因LEAFY的启动子上。他已经证明，LEAFY启动子包含一种赤霉素反应元件，这对启动子在短时间内的活性是必不可少的。他还通过功能丧失和功能获得的突变，确定了几个影响开花所需赤霉素的FOG和GAT基因。他现在建议(1)确定与多叶启动子相互作用的因子来传递GA反应；(2)将新发现的FOG和GAT基因整合到当前的花诱导途径框架中；(3)研究开花特异的FOG1、FOG2和GAT1-3基因的分子生物学；(4)更详细地描述FOG4，它强烈地影响包括萌发和开花在内的几种赤霉素反应。花对人类生存的重要性怎么强调都不为过。它们不仅是植物繁殖的器官，而且它们的直接产品是水果和种子，包括谷物，这些东西提供了人类消耗的大部分卡路里。因此，了解植物如何调控花的形成可能具有长期的实际应用。这项研究将作为理解为什么不同植物的开花可以以相反的方式对相似信号做出反应的起点。从拟议的研究中获得的详细的机理知识将使我们能够在未来微调重要作物的开花反应。

The transition from vegetative growth to flowering is controlled both by environmental and endogenous cues. Understanding where and how these signals are integrated is a prerequisite for understanding why similar environmental or endogenous cues can elicit opposite flowering responses in different plants. For example, while the plant hormone gibberellin generally induces flowering in rosette plants such as Arabidopsis, it inhibits flowering of several other plants. Similarly, Arabidopsis flowers faster in long than in short days, while other plants flower preferentially, or even exclusively, in short days. Dr. Weigel proposes complementary biochemical, physiological, molecular and genetic approaches to determine how gibberellins induce flowering in Arabidopsis. He has shown that, in Arabidopsis, flowering signals converge on the promoter of the floral identity gene LEAFY. He has shown that the LEAFY promoter contains a gibberellin-response element that is essential for promoter activity in short days. He has also identified, by loss- and gain-of-function mutageneses, several FOG and GAT genes, which affect the gibberellin-requirement for flowering. He now proposes (1) to identify the factor that interacts with the LEAFY promoter to confer GA response; (2) to integrate the newly discovered FOG and GAT genes into the current framework of floral inductive pathways; (3) to study the molecular biology of the flowering-specific FOG1, FOG2 and GAT1-3 genes; and (4) to characterize in more detail FOG4, which strongly affects several gibberellin responses, including germination and flowering.The importance of flowers for human sustenance cannot be overstated. Not only are they organs of plant reproduction, but their immediate products are fruits and seeds, including cereal grains, which provide the majority of calories consumed by humans. Thus, understanding how plants regulate the formation of flowers is likely to have long-ranging practical applications. This research will serve as a starting point for understanding why flowering of different plants can respond in opposite ways to similar signals. The detailed mechanistic knowledge gained from the proposed studies will enable us in the future to fine tune flowering responses of important crop plants.