杨梅W染色体决定雌性的关键功能基因的研究

Dioecy, with the male and female flowers on distinct individuals, has evolved independently in multiple plant lineages, the sex determination and genes involved in this differential development only uncovered in a few species with XY chromosome. Morella rubra is the only edible fruit species in the genus Morella, family Myricaceae, order Fagles that is used for commercial cultivation. Most of species within Morella are dioecious. By whole genome comparison between the female and male and association analysis with sequences of bulked samples from female and male, the ZW sex determination of Morella were identified with a 59-Kb non-recombinant region located on distal end of pseudo-chromosome 8. FSR contains abundant transposable element and seven putative genes, which may likely derived from duplication and rearrangement of paralogous genes. However the key genes involved in the sex differentiation are still unknown. In this project, the genes of FSR and their homologous will be analyzed combine with transcriptome of female and male buds, level of gene expression will determined in different organs, evolutionary of key candidate genes and homologous between different species will investigated, and functional transgenic in Arabidopsis thaliana and Nicotiana tabacum and interaction pattern of key genes will be identified. The research will be helpful to clarify the he molecular mechanism of the sex determination in Morella rubra, which will enrich the theory of molecular mechanism of plant with ZW sex determination and provide theoretical basis for studying sex determination in other plants.

雌雄异株植物在不同种系间是独立进化的，其性别分化分子调控机制仅在少量具有XY型物种上研究的较为透彻。杨梅是壳斗目杨梅科杨梅属植物中唯一用于水果商业栽培的物种。大部分杨梅属植物为雌雄异株，前期通过比较杨梅雌、雄全基因组和BSA混池序列比较发现其性别决定遗传机制为ZW型，并在LG8的末梢有59Kb的非重组雌特异区域(FSR)。FSR包含大量转座子和7个候选基因，可能来源于同源区域的复制和重排，但性别分化关键基因尚不清楚。本研究通过结合雌、雄花芽发育关键时期的转录组分析对雌特异区域的基因及其同源基因进行不同组织的表达模式分析、不同物种间的进化分析、拟南芥和烟草过表达分析、基因之间的互作模式探索等方面研究杨梅性别分化的分子调控机理。同时检测该机制在杨梅属不同物种间的保守性。研究结果将有助于阐明杨梅雌雄花性别分化的分子机制，丰富ZW型性别决定机制的分子调控机理，为其他植物性别研究提供理论指导。

雌雄异株植物的性别分化分子调控机制在XY型物种上研究的较为透彻。明确性别调控机制和调控因子对现代育种具有重要的指导意义。杨梅是我国南方特色亚热带果树，大部分杨梅属植物为雌雄异株。前期研究结果推断杨梅性别决定遗传机制为ZW型，且在LG8的末梢有59Kb的非重组雌特异区域(FSR)。FSR包含7个候选基因，但性别分化关键基因尚不清楚。本研究通过结合雌、雄花芽发育关键时期的转录组分析发现乙烯相关基因是调控花芽分化的重要因子。应用前期开发的SSR标记和性别特异标记评价杨梅雌雄自然群体，筛选出11个与性别关联的标记，且6个位于LG8上。基于MrFT2开发雌特异标记在杨梅杂交群体‘荸荠’x‘东魁’F1代扩增雌雄比为3:1且杂交后代基因型比率符合1:1:1:1，进一步证明杨梅ZW型性别决定系统，且雌性性状是由位于LG8的显性单基因（W）控制。通过对蜡杨梅雌、雄混池进行BSA测序分析筛选到与性别关联的14.89Mb的区域，且与杨梅FSR区域比较发现两者共有的FT2基因，基于FT2基因开发性别关联引物在杨梅和蜡杨梅雌雄个体上均得到验证，说明性别决定区域的保守型。拟南芥中过表达杨梅MrFT2可以提早开花并且雄蕊数量减少，因此推测杨梅中MrFT2基因通过抑制雄蕊的产生来调控雌性，是杨梅雌雄异型的上游基因。蜡杨梅基因组测序为植物性染色体进化、比较基因组学、抗盐碱以及现代育种研究奠定基础。