瘿椒树属的性别决定及雄全异株繁育系统的进化

Tapiscia sinensis Oliv (Tapisciaceae) as one of the tertiary relic plant species, is an endangered species in China famous for its androdioecious breeding system in which populations consist of both of male and hermaphrodite individuals. It has great theoretical value to explore the evolutionary dynamics and evolutionary direction of the angiosperm reproductive system and the evolution of plant life history through the study of the origin and evolution of this androdioecious plant Tapiscia. In this project, we used the genus Tapiscia plant species as main object study, comparison of male and bisexual flower ontogeny of sex differentiation and temporal pattern. We will use of hybrid experiment and genetic markers to elucidate the genetic basis and the formation mechanism of Tapiscia genus sex determination. We use tools of chloroplast sequence fragment, SSR, SRAP, and nuclear DNA markers and molecular population genetics to reveal its genetic relationship among species, populations, divergence time, and sex individuals, reconstruction evolutionary sex differentiation history of Tapiscia sinensis. By using population genetics to clarify the correlation of between the phylogenetic evolution and gender two states formed. We verification of Tapiscia sinensis androdioecious species originated in the hermaphrodite ancestor hypothesis from the developmental genetics and evolutionary genetics, which reveals the genus Tapiscia breeding system evolution history, dynamics and direction of androdioecy. we will try to inquire the role of androdioecy in the evolution from hermaphroditism toward separate sexes （dioecy）. At the same time, it will provide new evidence to improve the evolutionary theory of angiosperm reproductive system.

我国特有第三纪孑遗植物瘿椒树种群中雄株与两性株共存，为罕见的雄全异株繁育系统。通过该古老被子植物雄全异株的起源和进化研究，对探明被子植物繁育系统进化动力和演化方向，植物生活史进化具有重要意义。本项目拟以瘿椒树属植物为研究对象，比较雄花与两性花个体发育过程、性别分化的时空模式，利用杂交实验和遗传标记技术，揭示瘿椒树属性别决定的遗传基础和性别二态性形成机制。基于叶绿体基因和核基因分子标记对瘿椒树属不同种群进行群体遗传学研究，分析种间、种群间、性别群体间亲缘关系及分化时间，重建物种的群体进化历史和性别分化动态。阐明瘿椒树属系统进化与性别二态性形成相关性，从性别表达的发育遗传学和性别二态性的进化遗传学双重视角验证瘿椒树属雄全异株起源于两性花祖先的假说，揭示瘿椒树属繁育系统进化历史、动力和方向，探讨雄全异株在被子植物由雌雄同花向雌雄异株进化中所起作用。为完善被子植物繁育系统进化理论增添新证据。

瘿椒树为我国特有的第三纪孑遗植物，生活史中具有果实越年成熟的特性。瘿椒树祖先的果实是当年成熟的，果实越年成熟的特征可能于中始新世（65Ma）以后分化形成，也正是这一生活史的特征出现，使得瘿椒树成为该属中唯一在第三纪以后地球气候剧烈变化中存留下来的种类。瘿椒树种群中雄株与两性株共存，为罕见的雄全异株繁育系统。雄花由两性花原基中雌蕊原基发育异常造成的，属于I型单性花发育模式。乙烯、生长素和细胞分裂素等参与调控了雄花第四轮花器官异常发育，核糖体蛋白RPL10a基因的突变可能是造成瘿椒树雌蕊异常发育的关键因素。综上所述，瘿椒树属植物具有两性花祖先，果实越年成熟形成的花果同期，造成两性个体的巨大繁殖压力，资源分配严重偏雌的两性种群不稳定，雌性不育突变体（雄株）入侵两性种群，形成了雄全异株繁育系统使得瘿椒树种群延续至今。可以预测，随着两性花中雄性功能的逐渐退化，雄全异株繁育系统最终演化为雌雄异株。