The Role of LEAFY in the Evolution of Rosette-Flowering

[00:78161]鲍姆不同的植物种类开花的方式不同。这项工作的目的是阐明这些差异是如何通过基因活性和功能的改变而产生的。策略是比较遗传模式系统，拟南芥，与一些野生近缘种（Jonopsidium acaule， Leavenworthia alabamica和爱达荷州scapigera）在开花方式上的差异。拟南芥在一个细长的无叶花序上开花，而其他三种是“莲座花”，从莲座叶的叶腋上开花。系统发育数据表明，莲座花独立于花序花的祖先进化了三次。根据来自拟南芥和Jonopsidium的信息，这种差异可能反映了花分生组织识别基因LEAFY （LFY）调控的变化。本研究的目的是通过(1)鉴定LFY在爱达荷州和Leavenworthia州的表达；(2)从莲座花类群中克隆LFY同源基因（带完整启动子）并将这些基因引入拟南芥中来验证这一假设。如果含有外源LFY的拟南芥植物表现出修饰的LFY表达，这表明LFY启动子发生了进化。此外，如果转基因导致部分或完全转化为莲座花，最可能的解释是LFY位点的变化促进了莲座花的进化。因此，该研究将揭示LFY在开花形态进化中的作用，并将有助于阐明可用于研究形态和发育进化的遗传基础的一般方法

0078161Baum Plant species differ in the manner in which they bear their flowers. The aim of this work is to elucidate how such differences might arise through the modification of gene activity and function. The strategy is to compare the genetic model system, Arabidopsis thaliana, with some wild relatives (Jonopsidium acaule, Leavenworthia alabamica and Idahoa scapigera) that differ in the manner in which flowers are produced. Whereas Arabidopsis produces flowers on an elongated, leafless inflorescence, the other three are "rosette-flowering," producing flowering from the axils of rosette leaves. Phylogenetic data show that rosette-flowering evolved three times independently from inflorescence-flowering ancestors. Based on information from Arabidopsis and prior work on Jonopsidium it is likely that the difference in flower production reflects changes in the regulation of the flower meristem identity gene, LEAFY (LFY). The aim of this study is to test this hypothesis by (1) characterizing LFY expression in Idahoa and Leavenworthia and (2) by cloning LFY homologs (with intact promoters) from the rosette-flowering taxa and the introducing those genes into Arabidopsis. If Arabidopsis plants containing exogenous LFY show modified LFY expression this will suggest evolution in the LFY promoter. Additionally, If transgenes cause partial or complete conversion to rosette-flowering the most likely explanation is that changes at the LFY locus contributed to the evolution of rosette-flowering. The study will, therefore, shed light on the role of LFY in the evolution of flowering morphology, and will serve to clarify a general approach that can be used to study the genetic basis of morphological and developmental evolution