Functional Analyses of APETALA3-Like Genes

0110731爱尔兰花是被子植物的一个显著特征，但花的形态有很大的差异。基于拟南芥和其他几种高等真双子叶植物的结果，有人提出，尽管花结构变化很大，但控制花发育的分子机制在所有被子植物中是保守的。然而，这一假设尚未得到严格的检验。 一个关键的调控基因，花同源异型APETALA3（AP3）基因，已被证明是需要指定的花瓣和雄蕊在高等真双子叶植物拟南芥。 所描述的实验将解决一个更大的问题，即控制花发育的分子机制是否是保守的，或者通过调查其他被子植物物种中的AP3样基因的功能而产生分歧。 这些研究将在番茄和罂粟中进行。系统发育分析表明，在AP 3谱系中的重复事件发生在高等真双子叶植物的基部，导致这些物种中的两个AP 3样谱系：euAP 3谱系和TM 6谱系。 迄今为止，所有的功能分析都集中在euAP 3谱系基因的作用上，拟南芥AP 3基因是其中的一员。 旁系同源TM6谱系基因的作用目前尚不清楚，将通过在番茄中进行功能研究来解决，番茄是一种存在许多遗传和分子工具的物种。这些调查将包括筛选插入突变的TM6基因，转基因操作的TM6基因，和遗传实验，利用以前确定的番茄AP3插入突变。 低等真双子叶植物和基部被子植物只含有一个AP3样谱系。 这些基因在序列上与高等真双子叶植物TM6基因更相似，并被称为paleoAP3谱系基因。 一个paleoAP3谱系成员的功能将使用罂粟作为模型系统进行调查。这些研究将包括克隆和鉴定罂粟paleoAP3基因，并确定是否有任何先前确定的罂粟花同源异型突变对应于该基因的病变。 此外，将进行表达研究，以表征控制花发育的过程中，在这个物种。从这些研究中获得的结果将是有价值的，在阐明基因的复制和多样化是如何与基因功能的变化。 它们还将为发展新的和更严格的假说提供基础，以在分子遗传水平上解释花形态的形态创新是如何出现的。

0110731IrishFlowers are a defining characteristic of the angiosperms, yet there is wide variation in floral form. Based on results from Arabidopsis and several other higher eudicot species, it has been proposed that, despite the wide variation in floral architecture, the molecular mechanisms controlling floral development are conserved across all angiosperms. This hypothesis, however, has not been critically tested. One key regulatory gene, the floral homeotic APETALA3 (AP3) gene, has been shown to be required for specifying petals and stamens in the higher eudicot Arabidopsis. The experiments described will address the larger question of whether the molecular mechanisms controlling floral development are conserved or have diverged by investigating the functions of AP3-like genes in other angiosperm species. These studies will be carried out in tomato and in opium poppy.Phylogenetic analyses indicate that a duplication event in the AP3 lineage occurred at the base of the higher eudicots, leading to two AP3-like lineages in these species: the euAP3 lineage and the TM6 lineage. To date, all functional analyses have focussed on the role of the euAP3 lineage genes, of which the Arabidopsis AP3 gene is a member. The roles of the paralogous TM6 lineage genes are currently unknown and will be addressed by carrying out functional studies in tomato, a species for which a number of genetic and molecular tools exist. These investigations will include screening for insertional mutations in the TM6 gene, transgenic manipulation of the TM6 gene, and genetic experiments utilizing a previously identified tomato AP3 insertional mutation. The lower eudicots and basal angiosperms contain only one AP3-like lineage. These genes are more similar in sequence to the higher eudicot TM6 genes and are termed the paleoAP3 lineage genes. The function of a paleoAP3 lineage member will be investigated using opium poppy as a model system. These studies will include cloning and characterizing the opium poppy paleoAP3 gene and determining whether any of the previously identified poppy floral homeotic mutations correspond to lesions in this gene. In addition, expression studies will be carried out in order to characterize the processes controlling floral development in this species.The results obtained from these studies will be valuable in shedding light on how gene duplication and diversification are related to changes in gene function. They will also provide a basis for developing new and more rigorous hypotheses to explain, at the molecular genetic level, how morphological innovations in floral form have arisen.