A Study On Structure, Function And Evolution Of The MADS-box Genes Involved In Floral Development In Akebia Trifoliata

Flowers are arguably the most essential key innovation of the angiosperms. The architecture of angiosperm flowers is complex and diverse, especially in the basal eudicot speices. A considerable number of phylogenetic analyses have demonstrated that the MADS-box genes involved in the floral development are grouped into four different subfamilies: AP1/SQUA (class A), AP3/PI (class B), AG (class C/D) and SEP (class E), in which at least one or two large-scale gene duplication events have occurred before the origin of core eudicots. Therefore, the gene composition is different in diversified groups of angiosperms, which implies that the genes might regulate the floral development in various patterns because they have experienced different evolutionary histories. Considering that basal eudicots, as transition between basal angiosperms and core eudicots, are of great importance for us to understand the floral evolution of angiosperms, the floral origin of core eudicots, and the molecular mechanisms determining floral diversity of basal eudicots, detailed studies on the genes involved in the floral development from species of basal eudicots are necessary. In this study, we initiated investigation on Akebia trifoliata, a species of the basal eudicot family Lardizabalaceae. The results were summarized as follows:1. Morphology and ontogeny of inflorescence and flowers in A. trifoliataThe flowers of A. trifoliata are monoecious. Both male and female flowers have only three petaloid sepals and no petals. Using scanning electron microscopy (SEM), the initiation and development of the A. trifoliata flowers were investigated. The results showed that: 1) no petal primordia or additional sepal primordia initiate...