关键词: 植物蛋白质 , 农杆菌转化 , T-DNA转运 , 基因整合

Abstract: Agrobacterium tumefaciens is a kind of Gram-negative soil bacterium, which harbors tumor inducing (Ti) or root inducing (Ri) plasmid. The T-DNA on the plasmid can enter plant cells and integrate into the host genome, and further endows plants new characteristics by stable inheritance. Thus, Agrobacterium tumefaciens, as a most efficient transformation vehicle, has been widely used in genetic engineering study for most dicotyledonous and part of monocotyledonous plants. Agrobacterium-mediated transformation technology has several advantages including simple process, low cost, less gene silence, and few copies of target genes. However, the transferring of target genes into plant genome by Agrobacterium is a complicated biological process, during which a lot of Agrobacterium proteins and plant proteins interact with each other for the mission of importation, transportation and integration of T-DNA. Associated host proteins play important roles almost in each step of the transformation of exogenous genes. For instance, AGPs, rhicadhesin binding protein, and vitronectin-like protein are involved in the Agrobacterium attachment to the surface of plant cells; GTPase and BTI proteins help T-DNA and Vir proteins enter plant cell; Actin, GIP, and VIP assist T-DNA transportation in plant protoplasm; VIP1, KAPa, PP2C, and Roc participate in the targeting and importing of T-DNA complex to plant cell nuclear, histones; VIP1 and VIP2 perform functions on the integration of T-DNA into plant genome. Due to the huge differences between plants in genomics, physiology and biochemistry, overexpression of some plant genes mentioned above do improve the transformation frequency in some plants mediated by Agrobacterium, while that doesn’t work in other plants. It was indicated that VIP1, VIP2, AGP and H2A are closely associated with the Agrobacterium-mediated transformation efficiency of some model plants like Arabidopsis and rice. However, the functions of these proteins in some recalcitrant plants to Agrobacterium infection such as wheat and maize are still undetermined. Thus, some novel proteins or genes associated with T-DNA transformation need to be isolated and identified in different plants. Presently, there are two marked features in the Agrobacterium-mediated transformation of plants. One is that the transformation technology of Agrobacterium-mediated for model plant species such as tobacco, Arabidopsis and rice is almost reaching a perfect level, and another one is that the technique is still difficult to be applied in some economically important crops including wheat, maize and soybean. Therefore, it is necessary to further investigate the roles of plant proteins associated with the transformation network in more plants. In this article, the plant proteins related to Agrobacterium infection and T-DNA delivery reported to date are reviewed to provide some useful information for the improvement of Agrobacerium-mediated transformation efficiency for some recalcitrant plants to be transformed.

Key words: plant proteins , Agrobacterium-mediated transformation , T-DNA transportation , gene integration