SWEET糖转运蛋白调控油茶果实糖分卸载及转运的分子机制研究

油茶是我国重要的木本油料作物，但其产业发展长期受低产制约，而产量形成主要取决于糖分向果实的卸载及转运。SWEET是近年来植物中发现的新型糖转运蛋白，模式植物中的研究显示其在库器官糖分卸载及籽粒发育过程中可能发挥重要作用。申请人前期已从油茶中鉴定出CoSWEET1-6。本项目拟进一步以油茶果实为对象，综合运用酵母异源表达、免疫组化、原位杂交、免疫电镜及单分子技术等多种细胞和生化手段研究CoSWEETs的糖转运吸收特性、时空表达、组织和亚细胞定位及作用位点；利用同源和异源转基因技术验证CoSWEETs表型及生物学功能；通过Split-ubiquitin膜蛋白酵母双杂交系统、双分子荧光互补和GST-pulldown等多种体内体外技术鉴定关键CoSWEETs的调控因子和互作蛋白，解析CoSWEETs在油茶果实发育过程中参与糖分转运的作用机制及调控通路，为最终揭示油茶产量形成机理奠定基础。

Camellia oleifera is an important woody oil crop in China, however, low production is the long-term factor restricting the healthy and efficient development of oil tea industry. Yield formation mainly depends on the phloem unloading and transport of sugar into fruit. SWEET is a new type of sugar transporter discovered in plant in recent years. Studies in model plant show that SWEET family members may play an important role in unloading and transport of sugar into sink organ and grain development. We previously identified SWEET family members CoSWEET1-6 in Camellia oleifera. In this project, using a combination of yeast heterologous expression, immunohistochemical localization, in situ hybridization and immunogold localization, single molecule technique based on VA-TIRFM，etc., the sugar transport characteristics, spatiotemporal expression, tissue and subcellular localization of CoSWEET1-6 we have screened will be investigated in Camellia oleifera fruit. Moreover, the phenotype and biological function of CoSWEETs will be verified by homologous and heterologous transgenic techniques in Camellia oleifera and Brassica napus. In addition, the regulatory factors and interaction proteins of key CoSWEETs genes will be identified in Camellia oleifera by split-ubiquitin membrane protein yeast two-hybrid system and verified by bi-molecular fluorescence complementation and GST-pull down, etc. The aim of the project is to clarify the function and regulation pathway of CoSWEETs involved in sugar transport during Camellia oleifera fruit development, thereby laying a foundation for revealing the mechanism of Camellia oleifera yield formation.