糖是决定梨果实风味的核心因素，而糖的跨膜运输是影响糖分在果实中积累和风味品质形成的关键步骤。本项目在前期研究中发现糖的跨膜转运PbSWEET基因家族成员在梨果实中高量表达，且具有发育时期表达特异性，但对其参与果实糖转运的功能和作用机制尚未有报道。本项目拟通过对不同梨品种资源PbSWEET基因家族的比较，明确序列结构变异对糖转运的影响；结合高糖与低糖品种转录表达差异分析，筛选出重要功能基因；通过酵母转化、荧光共振能量转移、梨和草莓果实瞬时表达、以及草莓子叶的稳定转化等技术验证PbSWEET基因对糖组份的转运功能和效率；并利用酵母单杂、双荧光素酶报告基因系统、膜蛋白酵母双杂、Pull-down和BiFC等技术鉴定上下游调控因子和互作基因，有望率先阐明PbSWEET基因对梨果实糖转运的功能及其分子作用网络。研究结果将为实现梨果实糖品质性状的遗传改良提供重要的理论依据和必要的基因资源。

The trait of sugar directly affects the sweetness of fruit, it is the core factor to determine the fruit flavor of pear. The trans-membrane transportation of sugar is the key step for sugar accumulation and plays the important role in fruit quality conformation. Based on our previous study, it was interested to find that trans-membrane transporter gene members in PbSWEET family showed high and specific expression pattern during fruit development in pear. However, the sugar transporter function and regulation mechanism of PbSWEET genes in fruit are still not know. In this project, the sequence comparison of PbSWEET gene members from different cultivars were used to clarify the effects of gene sequence and structure on sugar transporter, and the candidate PbSWEET genes were identified by transcriptome analysis between cultivars with high and low sugar content; the gene function were further verified by a series of experiments, including yeast transformation, FRET, transient expression in pear and strawberry fruit, and transformation in strawberry as well; the regulators or interaction genes were identified by Yeast single-hybrid system, Dual luciferase reporter gene system, Yeast two-hybrid system, Pull-down and BiFC analysis. It is expected to firstly clarify the function and the molecular mechanism of PbSWEET genes in sugar transportation. The results will helpful to provide the theory basis and necessary gene resources for genetic improvement of sugar trait in pear.