基于全基因组测序的油桐性别分化机制研究

Tung tree (Vernicia fordii) is an economically important industrial oil tree species, and tung oil could be used for production of green and environmental coatings. However, low yield of tung fruits have seriously restricted the industrial development of tung tree. During the process of differentiation of male and female, low proportion of female flowers is the major factor causing low percentage of fruit set. Our previous research showed that the unisexual flower of tung tree had the “bisexual” stage and male and female flowers have the potential for interconversion. We have completed the whole genome sequencing project of tung tree and obtained high-quality genome sequence data, and based on this, field survey, morphological anatomy, microscopic observation, hormone treatment, HPLC-MSn analysis, transcriptome sequencing, large-scale data exploring and genetics transformation will be performed in this project on cellular level, hormone metabolism and molecular level. The important hormone regulating sex differentiation of tung flowers will be screened and its function mechanism will be clarified. The key genes related to sex differentiation and their function will be figured out. The relationship between hormone regulation and sex-related genes regulation will be elucidated. Finally the mechanism of sex differentiation of tung tree will be completed uncovered. This project has important theoretical significance, and could provide scientific basis and technical support for high yield, stable yield and industrial upgrading in tung tree as well.

油桐（Vernicia fordii）是我国重要的木本工业油料树种，桐油是研发绿色环保涂料的重要原料。但油桐果实产量较低，严重制约了产业化发展。油桐雌雄分化过程中雌花比例过低是导致油桐座果率低的主要原因。项目组前期研究发现，油桐的性别分化经历过“两性”时期，雌雄花具有相互转化的潜力。本项目在完成油桐全基因组测序、组装的基础上，拟通过田间调查、形态解剖、显微观测、激素处理、HPLC-MSn分析、转录组测序、基因组数据深度挖掘和遗传转化等多种研究手段相结合，从细胞水平、激素代谢、分子水平三个层面，确定调控油桐花性别分化的重要激素类型，并明确其作用机制；筛选出性别分化关键基因、解析其功能，并明确性别基因调控与激素调控二者之间的关系，最终阐明油桐花性别分化的机制。项目研究不仅具有重要的理论意义，也可为油桐丰产、稳产、产业化升级提供重要科学依据和技术支撑。

油桐（Verniciafordii）是我国重要的木本工业油料树种，桐油是研发绿色环保涂料的重要原料。但油桐果实产量较低，严重制约了产业化发展。油桐雌雄分化过程中雌花比例过低是导致油桐座果率低的重要原因之一。.本项目在完成油桐全基因组测序、组装的基础上，通过田间调查、形态解剖、显微观测、激素处理、HPLC-MSn分析、转录组测序、基因组数据深度挖掘和遗传转化等多种研究手段相结合，从细胞水平、激素代谢、分子水平三个层面，（1）发现了外源6-BA是促进油桐雌花形成的一种重要植物生长调节剂；油桐花芽内源激素的含量变化可能通过抑制雄蕊原基相关基因和开花时间相关基因的表达，并促进花分生组织相关基因的表达，最终促进顶芽中雌蕊原基的形成，初步阐明了外源6-BA在油桐雌花分化中的作用机制。（2）发现了绒毡层的提前降解是导致雌花中雄蕊孢原母细胞发生细胞程序死亡的关键因素，也是导致雌花中雄蕊退化的关键因素；水杨酸的积累可能诱导雌花中雄蕊细胞程序性死亡相关基因的表达，并抑制花药和花粉发育基因的表达，特别是抑制了雌花中雄蕊绒毡层发育基因的表达，最终促使雌花中雄蕊退化，进而促进雌花的正常发育，探究了关键候选基因MYB35功能，阐明了油桐雌花发育的水杨酸途径。（3）研发了油桐催雌调控技术及促果剂产品，平均单株产量提高24.23%-27.75%，大幅提高了油桐产量。（4）基于项目研究，已发表学术论文3篇，待发表2篇；培养1名博士研究生，并获得获湖南省优秀博士学位论文；培养6名硕士研究生，其中2名已毕业；开展学术交流5次，分别获得“第六届中国林业学术大会”和“湖南省植物学会2021学术年会”优秀会议论文一等奖。.该项目圆满完成了项目书规定的研究内容，为下一步深入研究激素在油桐花性别分化中的调控机制奠定了重要基础。