农杆菌vir基因诱导因子研究进展

Advances on Factors Influencing Induction of Agrobacterium tumefaciens Virulence Genes

在众多遗传转化法中,农杆菌(Agrobacterium tumefaciens)介导法以易操作、低费用、插入片段明确、拷贝数低等独特优点成为植物遗传转化的首选。然而,至今仍有许多物种不能被农杆菌转化。研究表明,农杆菌的转化能力是由位于染色体基因组之外Ti质粒上的vir基因决定的。在所有vir基因中,除virA和virG组成型表达外,其它vir基因的表达均需酚类化合物的诱导;糖类物质可增强酚类化合物对vir基因的诱导;低磷酸和酸性pH环境也可促进vir基因的诱导表达。文章论述了酚类化合物、糖类物质、低磷酸、酸性pH和培养温度等因素对农杆菌vir基因诱导表达的影响,以期为更好地利用这一天然载体及为提高转化效率提供依据。

With advantages of easy-to-operate, low-cost, low copies and preferential integration of defined T-DNA into transcriptionally active regions of chromosomes without vector DNAs, Agrobacterium is employed for genetic modification of plants routinely. However, until recently, still there are a great many species recalcitrant to Agrobacterium-mediated transformation. Data suggest that the infection capability is designed by virulence （vir） genes of Ti plasmid outside of A. tumefaciens genome. Among all vir genes, virA and virG express constitutively, while other vir genes need phenolic compounds for induction. Besides, carbohydrates can enhance vir induction by phenolic compounds, while low phosphate and acidic pH environmental conditions may also increase induced expression of vir genes. In order to better utilize Agrobacterium and improve its efficiency tor applications in research and biotechnology, molecular mechanisms for vir induction by factors such as phenolic compounds, carbohydrates, low phosphate, acidic pH conditions and incubation temperature are discussed.