Modification of the ABC Program and the Evolution of Floral Novelty

了解新的形态特征是如何进化的已经成为快速发展的比较发育遗传学领域的一个主要焦点。在开花植物中，有人提出花形态的根本变化可能是由同源花器官同源基因表达域的简单变化介导的。然而，这一假设还没有经过仔细的检验，并且仍然没有解释在简单的“滑动边界”模型不足以解释形态的情况下，潜在的程序是如何被修改的。这些问题可以通过研究下毛茛科来解决，毛茛科包含了大量的花形态多样性。虽然初步数据表明该家族的ABC程序已被基因复制重塑，但需要进一步表征ABC基因同源物以澄清这些发现并测试其更广泛的适用性。为此，本项目的目的是：1)利用原位杂交技术分析水蛭AP3、PI、AG和AP1同源物在水蛭中的表达模式；2)利用扫描电子显微镜（SEM）、基因表达研究、候选基因测序和遗传分离分析等方法对寻常蒿同源突变体进行鉴定；3)测定水蛭AP3和PI同源物的蛋白二聚化和DNA结合能力；4)利用抗体定位法，确定了AP3、PI、AG和AP1基因产物在水仙、单纯黄病菌、铁线莲、高山铁线莲和毛茛中的蛋白分布。除了研究花形态的进化外，这些研究还将解决诸如核心花序外器官身份基因功能的保护以及基因复制在新发育程序进化中的作用等问题。就更广泛的影响而言，该项目将为本科生、研究生和博士后提供培训。

Kramer0319103Understanding how new morphological characters evolve has become a major focus of the rapidly growing field of comparative developmental genetics. In flowering plants, it has been proposed that radical changes in floral morphology may have been mediated by simple shifts in the expression domains of homeotic floral organ identity genes. This hypothesis has not been carefully tested, however, and still leaves unexplained the question of how the underlying program may have been modified in cases where a simple "sliding boundary" model is insufficient to explain morphology. These issues can be addressed through studies of the lower eudicot family Ranunculaceae, which contains a great diversity of floral morphology. Although preliminary data suggest that the ABC program in this family has been reshaped by gene duplications, further characterization of ABC gene homologs is necessary to clarify these findings and test their broader applicability. To these ends, the objectives of the project are: 1) to analyze the expression patterns of AP3, PI, AG, and AP1 homologs in Aquilegia vulgaris using in situ hybridization; 2) to characterize homeotic mutants of A. vulgaris using SEM, gene expression studies, candidate gene sequencing and analysis of genetic segregation; 3) to determine the protein dimerization and DNA binding capabilities of AP3 and PI homologs from Aquilegia vulgaris; and 4) to use antibody localization to determine the protein distribution of AP3, PI, AG and AP1 gene products in Aquilegia vulgaris, Xanthorhiza simplicissima, Clematis integrifolia, Clematis alpina and Ranunculus ficaria. In addition to investigating the evolution of floral morphology, these studies will address issues such as the conservation of organ identity gene function outside the core eudicots and the role of gene duplication in the evolution of novel developmental programs. In terms of broader impact, this project will provide training for undergraduate, graduate and postdoctoral students.