T-DNA转移及整合的分子机制研究进展

农杆菌介导的外源基因转化是目前植物转基因应用比较广泛的方法。近年来关于农杆菌介导的整合机制的研究已经取得了很大的进步。研究表明，在VirD2和VirE2协助下，农杆菌转移T-DNA进入植物细胞，这两种蛋白共同协助T-DNA完成转移、核定位及在植物基因组中的整合。近年来关于拟南芥突变体的研究表明，被转化植物的宿主基因在T-DNA转移及整合过程中发挥主要的作用。通过对现有研究成果详细讨论了Vir’蛋白(VirD2和VirE2)及植物基因在农杆菌介导植物转化中的作用，详细讨论了依靠VirD2蛋白和SDSA(synthesis-dependent strand-annealing)整合的两类不同的整合模式，根据最新的研究成果阐述了以基因组的双链断裂修复为基础的整合模型，并提出新的观点。

Progress on Molecular Mechanism of T-DNA Transport and Integration

Agrobacterium mediated transformation is probably the most widely used method to introduce genes into plants.Great progress has been made in recent years in studies on the mechanism of Agrobacterium mediated transformation. Agrobacterium genetically transforms plants by transferring a portion of the resident Ti plasmid,the T DNA,to the plant.VirD2 and VirE2 accompany the T DNA into the plant cell.Both proteins may aid in T DNA transfer,nuclear targeting and integration into the plant genome.In recent years,some Arabidopsis rat (resistant to transformation) mutants are deficient in T DNA integration according to some studies.These results showed that plant genes participate in the T DNA transport and integration process.This paper discusses our current knowledge about the functions of virulence protein,namely VirD2 and VirE2,and plant genes in several aspect of Agrobacterium transformation.The paper discusses two different classes of integration patterns in detail:one is T DNA right border being linked to genomic sequences by the VirD2 protein,the other is T DNA integration via SDSA (synthesis dependent strand annealing).According to the latest studies we elaborated the T DNA integration model based on genomic DSB (double strand breaks) and proposed a new opinion about the mechanism of T DNA integration.