与丛枝菌根真菌（AMF）共生是提高养分效率的重要途径之一，然而共生系统的形成也增加了植物根系的碳库压力。植物蔗糖转运蛋白在调控寄主的碳分配，实现植物最大化获利中起重要作用，但相关研究鲜有报道。本项目首先研究受菌根特异诱导表达的大豆蔗糖转运蛋白基因GmSUT5和GmSUT6对养分缺乏，以及碳消耗强度不同的AMF侵染的表达响应；接着，并利用过量和干涉大豆转基因株系，结合14C、15N、33P同位素标记，研究AMF侵染对植株体内碳库的影响；此外，通过酵母互补和爪蟾卵母细胞实验系统，确定GmSUT5和GmSUT6的蔗糖吸收和外排动力学特性；并利用启动子融合GUS的转基因植株，进行GUS和菌根侵染结构染色的组织共定位分析，最终阐明其调控大豆-AMF共生体内碳分配的生理和分子机制。

Symbiosis with arbuscular mycorrhizal fungi (AMF) is an important strategy for improving nutrient efficiency. However, the formation of symbiosis system also increases the pressure of carbon sink in plant roots. Sucrose transporters play very important roles in regulating carbon allocation and realizing the maximum profits of host plants. However, until now, there are few reports on it. In this project, firstly, the expression patterns of mycorrhiza-induced sucrose transporters GmSUT5 and GmSUT6 are investigated in responses to nutrient deficiency and inoculation of AM fungi with different carbon cost intensity. Subsequently, over-expressing and RNAi transgenic plants will be labeled with 14C、15N、33P to elucidate the effect of AM inoculation on carbon sink in soybean-AM symbiotic system. In addition, sucrose absorption and release kinetics of GmSUT5 and GmSUT6 will be analyzed by yeast heterologous expression system and Xenopus oocyte system. Moreover, promoter-GUS transgenic plants are employed to analyze co-localization of GmSUT5 or GmSUT6 with both GUS and AM structure staining. The results will elucidate the physiological and molecular mechanisms of GmSUT5 and GmSUT6 regulation of carbon partitioning in soybean-AM symbiotic system.