The Role of Meristem-Identity Genes in Floral Patterning

维格尔9723818的花产生水果和种子，这包括所有的谷物，因此提供了人类消耗的大部分卡路里。因此，无论从科学角度还是从经济角度来看，了解花发育的机制都很有趣。这项建议侧重于花内器官的模式是如何产生的这一特殊问题。需要研究的具体问题是，编码单个花启动的主开关的全球调控因子LEAFY如何控制同源异型基因APETALA3的活性，APETALA3的表达仅限于花瓣和雄蕊形成的区域。虽然LEAFY在形式上是同源异型基因的上游调控因子，但目前还不清楚这种转变是如何从普遍存在的LEAFY RNA和蛋白质表达向下游基因的区域特异性表达转变的。在之前的资助期间，魏格尔博士开发了几种工具来解决这个问题。首先，他证明了APETALA3的激活是由LEAFY和部分必要的辅助调节因子UFO共同介导的。其次，他已经证明了在花中UFO本身的正确表达模式需要有叶的，这通常在有叶之后激活，但在APETALA3之前。第三，他已经证明，在转基因植物中修改LEAFY的转录激活潜力会改变下游同源异型基因的表达模式，这表明LEAFY编码了一种直接作用于这些靶基因的转录因子。他现在建议详细研究LEAFY和UFO如何合作激活APETALA3，具体目的如下：1.LEAFY的激活版本能否绕过UFO活性的要求？2.LEAFY蛋白是单独还是与UFO一起直接与APETALA3序列相互作用？3.LEAFY是如何反过来调节UFO的表达模式的，LEAFY是花中UFO的激活剂，还是LEAFY仅仅优化了FLOW中的UFO表达模式？这些实验得出的结论不仅对对花发育感兴趣的科学家有意义，而且应该适用于任何多细胞生物体中的模式形成问题。

Weigel 9723818 Flowers give rise to fruits and seeds, which include all cereals, and thereby provide the majority of calories consumed by humans. Understanding the mechanisms of flower development is therefore interesting both from a scientific and from an economic point of view. This proposal focuses on the particular problem of how the pattern of organs within flowers is generated. The specific problem to be investigated is how a global regulator, LEAFY, which encodes a master switch for the initiation of individual flowers, controls the activity of a homeotic gene, APETALA3, whose expression is limited to the areas of the flower that will give rise to petals and stamens. While LEAFY is formally an upstream regulator of homeotic genes, it remains unclear how the transition is made from ubiquitous expression of LEAFY RNA and protein to region-specific expression of downstream genes. During the previous funding period, Dr. Weigel has developed several tools to address this problem. First, he has shown that activation of APETALA3is mediated by LEAFY in conjunction with a partially dispensable co-regulator, UFO. Second, he has shown that LEAFY is required for the proper expression pattern of UFO itself within flowers, which is normally activated after LEAFY, but before APETALA3. Third, he has shown that modifying the transcriptional activation potential of LEAFY in transgenic plants changes the expression patterns of downstream homeotic genes, suggesting that LEAFY encodes a transcription factor that acts directly on these target genes. He now proposes to investigate in detail how LEAFY and UFO cooperate to activate APETALA3, with the following specific aims: 1. Can an activated version of LEAFY bypass the requirement for UFO activity? 2. Does LEAFY protein, alone or together with UFO, interact directly with APETALA3 sequences? 3. How in turn is the expression pattern of UFO regulated and is LEAFY an activator of UFO in flowers, or does LEAFY merely refine the UFO expression pattern in flo wers? The conclusions drawn from these experiments will have not only implications for scientists interested in flower development, but should be applicable to the problems of pattern formation in any multicellular organism.