Evolution of combined versus seperate sexes in flowering plants

尽管性在生物生物学中扮演着中心角色，但令人惊讶的是，人们对涉及不同性别的生殖系统是如何以及为什么出现的知之甚少。对性系统的遗传控制背后的进化过程的了解更少。植物的性系统之所以特别令人感兴趣，不仅是因为它们在农业上的重要性，而且还因为它们的复杂性和它们为研究不同性别的逐渐进化提供了独特的机会。植物类群的性别系统表现出变异性，具有不同的性别决定模式，是研究性别决定染色体进化的理想背景。我们已经选择了一个小的欧亚分支葫芦科，包括属Bryonia和Ecbalidae，与它研究植物的单独和联合性别的进化和性别决定染色体的进化。在这个分支中的物种是雌雄同株或雌雄异株，性系统甚至可以在种群之间变化，显然取决于栖息地。以前在实验室的工作已经澄清了这一组内的系统发育和地理关系。这为我们提供了一个强有力的比较框架，我们可以用它来研究不同物种染色体上性别决定区域的组织。这项拟议中的研究将回答有关性连锁DNA区域进化以及性染色体起源和组成的问题。我们要求资助（1）序列上游和下游的AFLP标记连锁的男性在Bryonia dioica和分析这些序列的分子系统发育框架，（2）构建一个BAC文库的B。dioica，以便通过荧光原位杂交（FISH）进行染色体绘画。这项研究计划的最终目标是有助于更好地了解植物中单独和组合性别的进化以及性别决定。

Despite the central role of sex in organismal biology, surprisingly little is known about how and why reproductive systems involving separate sexes have arisen. Even less is understood about the evolutionary processes that underlie the genetic control of sexual systems. The sexual systems of plants are of specific interest not just because of their obvious agricultural importance but also because of their complexity and the unique opportunity they present to study the gradual evolution of separate sexes in general. Plant groups that exhibit variability in their sexual systems and that have different modes of sex determination are the ideal context in which to study the evolution of sex determining chromosomes. We have selected a small Eurasian clade of Cucurbitaceae, comprised of the genera Bryonia and Ecballium, with which to study the evolution of separate and combined sexes in plants and the evolution of sex-determining chromosomes. Species in this clade are either monoecious or dioecious, and sexual systems can even vary between populations, apparently depending on habitat. Previous work in a lab has clarified the phylogenetic and phylogeographic relationships within this group. This provides us with a strong comparative framework that we can use to study the organization of sex determining regions on the chromosomes among the various species. The proposed study will answer questions about the evolution of sex-linked DNA regions, and the origin and composition of sex chromosomes. We request funding (1) to sequence up- and down-stream from AFLP markers linked to the male sex in Bryonia dioica and analyse those sequences in a molecular phylogenetic framework and, (2) to construct a BAC library of B. dioica in order to perform Chromosome Painting via fluorescence in-situ hybridization (FISH). The ultimate goal of this research program is to contribute to a better understanding of the evolution of separate and combined sexes and of sex-determination in plants.