梨是我国重要的果树种类。矮化密植栽培具有结果早、产量高、品质优、便于管理、机械化生产程度高等特点，是梨树栽培生产的必然趋势。世界梨生产国都把选育适宜的梨矮化砧作为科学研究的热点。而目前限制矮化砧木选育的主要瓶颈是致矮机理的不清晰。生长素被普遍认为和植物个体大小有着最为直接和密切的关系，其含量及运输也成为砧木致矮研究中的重要方向。本课题组前期通过国内外资源收集与传统杂交育种，得到一批致矮程度不同的梨属砧木。通过研究发现，不同矮化类型砧木嫁接组合中砧木及接穗茎皮内IAA含量明显低于乔化砧木嫁接组合。本研究拟从生长素转运蛋白PIN1入手，结合转基因功能验证，微嫁接，RNA-seq及代谢谱分析等技术，以期从生长素运输方面解析梨矮化砧木的致矮机理，为梨矮化砧木的培育提供基因储备和理论指导。

Pear is an important fruit tree species in China. Dwarf and dense cultivation has many advantages, such as early harvest, great yield, excellent quality, easy management, high mechanization, etc, which is an inevitable trend in the pear cultivation production. So breeding the rootstocks with dwarfing effect is always the focus of scientific research in the worldwide. But the unclear dwarfing mechanism is the main bottleneck which restricts the dwarf rootstock breeding at present. Auxin is widely considered having the most direct and closest relation with plant size. And the content and transport of auxin are important direction in the study of the dwarfing rootstocks. We got a series of rootstocks with different dwarfing effects through resource collection worldwide and the traditional crossbreeding techniques. We also found that the IAA content in the bark of the grafting combination with dwarfing rootstocks is much higher than that with common rootstocks. In our research, we isolate the auxin transporters gene PIN1. And combined with the technologies of transgenic tunction annotation, micro grafting, RNA-seq and metabolic spectrum analysis, our goal is to analyze the dwarfing mechanism of pear rootstocks in the aspects of auxin transport, and provide new gene and theoretical guidance for breeding new dwarfing pear rootstocks.