Studies in Floricaula/LEAFY Gene Phylogeny in Basal Angiosperms and Spore Bearing Plants

9964374 Frohlich我们的工作表明同源异型基因Floricaula/LEAFY（LFY）可以为植物主要分类群的系统发育关系提供非常有力的证据。 这主要是由于该基因的氨基酸序列变化速度缓慢，部分原因是在种子植物进化的早期，基因复制切断了“长分支”。 我们将获得LFY序列，以解决1）主要孢子携带群体之间的关系（薄囊蕨属、葡萄孢属（属于真囊蕨属）、马尾蕨属、裸盖蕨属和种子植物，或许还有地钱属、藓类和石松属，和2）基部开花植物群，包括诸如睡莲、木兰属、金鱼藻属，我们最简约的基因树显示了在开花植物谱系分离之前的重复事件。 如果这是真的，这将意味着开花植物最初有LFY基因的第二个拷贝，随后丢失。 这一观察结果提出了另一种基于发育遗传学的花进化理论。 然而，基因树的这一部分是不确定的，这使得该理论的支持率很低。对主要植物类群进行系统发育分析所需的相同序列数据也应该更牢固地建立基因树中的分裂顺序。 这可能会更确定地显示，复制是否先于显花植物的分化，因此显花植物是否有第二个LFY基因丢失。

9964374FrohlichOur work has shown that the homeotic gene Floricaula/LEAFY (LFY) can provide very strong evidence on phylogenetic relationships of major plant taxonomic groups. This is due mostly to the slow rate of change of the amino acid sequence of the gene, and partly because a gene duplication cut a "long branch" early in the evolution of seed plants. We will obtain LFY sequences to address relationships among 1) the major spore bearing groups (leptosporangiate ferns, Botrychium (of the Eusporangiate ferns), horsetails, Psilotum and seed plants, and perhaps also liverworts, mosses and lycopods and 2) the basal flowering plant groups, including such plants as waterlily, Magnolia, Drimys Ceratophyllum, etc. Our most parsimonious gene tree shows the duplication event preceding the separation of the flowering plant lineage. If true, this would mean flowering plants originally had a second copy of the LFY gene, which was subsequently lost. This observation suggests an alternative theory of flower evolution, based on developmental genetics. This part of the gene tree is uncertain, however, making the theory weakly supported. The same sequence data needed for phylogenetic analysis of the major plant groups should also more firmly establish the order of splittings in the gene tree. This may show, with more certainty, whether the duplication preceded the divergence of flowering plants, and so whether flowering plants had a second LFY gene that was lost.