根癌农杆菌不仅是一种植物病原菌，由其介导的遗传转化更是植物遗传改良的关键手段。农杆菌介导的遗传转化过程极其复杂，其机理在很大程度上仍不清楚。我们发现农杆菌毒力蛋白VirD5是农杆菌侵染过程中一个潜在的转录因子，能识别一个保守的DNA元件，能与含有该DNA元件的宿主基因At3g49480启动子结合，敲除virD5基因导致农杆菌对宿主的稳定转化效率下降并影响At3g49480的表达。我们还发现VirD5可以与MicroRNA合成相关蛋白CBC复合体竞争性结合拟南芥VIP2。本项目拟对VirD5及其调控的宿主靶基因At3g49480在农杆菌侵染过程中的功能进行分析，对VirD5与VIP2等相关蛋白相互作用的生物学意义进行阐释，其结果将有助于揭示农杆菌和宿主相互作用的分子机制，为有效控制冠瘿病危害，扩大农杆菌介导的遗传工程的应用范围和提高农杆菌介导的遗传转化效率奠定理论基础。

Agrobacterium tumefaciens not only is a plant pathogen, but also mediates plant genetic transformation that is the key method for plant genetic improvement. The infection process of Agrobacterium is very complicated, and its mechanism is largely unclear. We found that Agrobacterium virulence protein VirD5 is a putative transcription factor in Agrobacterium infection process. It recognizes a specific DNA element and can bind to the promotor of the host gene At3g49480 that contains the element. Knocking-out of virD5 causes reduction of Agrobacterium mediated stable transformation and affects the expression of At3g49480 gene. We also found that VirD5 can compete with the MicroRNA biosynthesis-related CBC complex for binding to the host Arabidopsis protein VIP2. In this project, we propose to analyze the function of VirD5 and VirD5-regulated host target gene At3g49480 in the Agrobacterium infection process, and elucidate the biological significance of the interaction between VirD5 and VIP2. The results will be conducive to uncovering the molecular mechanism of Agrobacterium-host interactions, and provide theoretical basis for protecting crops from the crown gall disease, enlarging the application range of Agrobacterium-mediated genetic engineering and improving the efficiency of Agrobacterium-mediated genetic transformation.