根瘤农杆菌T-DNA结合蛋白VirD2和VirE2在水稻中的亚细胞定位研究

Subcellular Localization of Agrobacterium tumefaciens T-DNA Binding Proteins VirD2 and VirE2 in Rice

根瘤农杆菌侵染植物过程中,至少有5种毒性蛋白(Vir)进入宿主细胞发挥作用,而其中VirD2与VirE2的作用最为关键,研究二者在水稻中的亚细胞定位,对农杆菌介导的水稻遗传转化机制的阐明具有重要意义。利用水稻叶鞘原生质体瞬时表达系统,发现3种冠瘿碱型的VirD2均只定位于细胞核中,与在拟南芥中相同;而3种冠瘿碱型的VirE2均主要定位于细胞核中,但在细胞质中仍有较多分布,与在拟南芥中的定位不同。因此,推测不同冠瘿碱型的农杆菌对水稻侵染能力的差异与VirD2和VirE2亚细胞定位的关系不大;同时表明根瘤农杆菌介导的拟南芥及水稻遗传转化机制存在相似性,但也有不同之处。

In the process of Agrobacterium tumefaciens-mediated infection of plants, at least 5 virulence （Vir） proteins play roles by entering the host cells, among which VirD2 and VirE2 are the key factors. Consequently, studying the sub-cellular localization of VirD2 and VirE2 in rice is crucial to understand the mechanism of Agrobacterium tumefaciens-mediated rice genetic transformation. Using the transient expression system of rice sheath protoplasts, we found that the VirD2 proteins of all 3 kinds of opine Agrobacterium are completely located in the nucleus, which is the same as in Arabidopsis ; and the VirE2 proteins of all 3 kinds of opine Agrobacterium are mainly located in nucleus, but are also distributed in the cytoplasm, which is different from those in Arabidopsis. Therefore, we propose the different efficiency among the 3 kinds of opine Agrobacterium strains for rice genetic transformation is not mainly determined by sub-cellular localization of VirD2 and VirE2. In addition, our results demonstrate that the mechanism of Agrobacterium tumefaciens-mediated genetic transformation in rice and Arabidopsis share some similarities, but keep some differences.