Gibberellins and Floral Induction in Arabidopsis

从营养生长到开花的转变受环境和内源因素的控制。 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性线索可以在不同植物中引起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诱导莲座植物如拟南芥的开花，但它抑制几种其他植物的开花。 类似地，拟南芥在长日照时比短日照时开花更快，而其他植物则优先或甚至完全在短日照时开花。 Weigel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如何诱导拟南芥开花。 他已经证明，在拟南芥中，开花信号集中在花身份基因LEAFY的启动子上。 他已经证明LEAFY启动子含有一个赤霉素反应元件，该元件对于启动子在短时间内的活性是必需的。 他还通过功能突变的丧失和获得鉴定了几个影响开花所需赤霉素的FOG和GAT基因。 他现在提出：（1）鉴定与LEAFY启动子相互作用以赋予GA反应的因子;（2）将新发现的FOG和GAT基因整合到现有的成花诱导途径框架中;（3）研究成花特异性FOG 1、FOG 2和GAT 1 -3基因的分子生物学;（4）更详细地描述FOG 4，它强烈影响几种赤霉素反应，包括发芽和开花。花对人类生计的重要性怎么强调都不过分。 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，提供了人类消耗的大部分卡路里。 因此，了解植物如何调节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的信号做出反应的起点。 从拟议的研究中获得的详细机制知识将使我们能够在未来微调重要作物植物的开花反应。

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.