Modification of the ABC Program and the Evolution of Floral Novelty

Kramer0319103了解新的形态特征如何进化已成为快速发展的比较发展遗传学领域的主要焦点。在开花植物中，已经提出花形态的根本变化可能是由同源异型花器官识别基因表达结构域的简单转移所介导的。然而，这一假说没有经过仔细的测试，仍然没有解释这样一个问题：在简单的“滑动边界”模型不足以解释形态的情况下，潜在的程序可能已经被修改了。这些问题可以通过研究较低的龙舌兰科来解决，它包含了非常多样化的花形态。虽然初步数据表明，该家族中的ABC程序已被基因复制重塑，但有必要对ABC基因同源物进行进一步表征，以澄清这些发现并测试其更广泛的适用性。为此，本项目的目标是：1)利用原位杂交技术分析AP3、PI、AG和AP1同源基因在普通阿奎莱中的表达模式；2)利用扫描电子显微镜、基因表达研究、候选基因测序和遗传分离分析来鉴定普通阿奎兰的同源异型突变体；3)确定普通阿奎莱AP3和PI同源基因的蛋白质二聚化和DNA结合能力；以及4)利用抗体定位来确定AP3、PI、AG和AP1基因产物在普通阿奎莱、简单苍耳、铁线莲花、铁线莲和毛茅中的蛋白分布。除了研究花形态的进化外，这些研究还将讨论核心真叶外器官特征基因功能的保存以及基因复制在新的发育程序进化中的作用等问题。在更广泛的影响方面，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.