Escudero J., Hohn B.
Friedrich Miescher-Institut, Postfach 2543, CH-4002 Basel, Switzerland.
Plant Cell. 1997 Dec;9(12):2135-2142. doi: 10.1105/tpc.9.12.2135.
Agrobacterium colonizes plant cells via a gene transfer mechanism that results in plant tumorigenesis. Virulence (vir) genes are transcriptionally activated in the bacteria by plant metabolites released from the wound site. Hence, it is believed that agrobacteria use injuries to facilitate their entrance into the host plant and that the wounded state is required for plant cell competence for Agrobacterium-mediated gene delivery. However, our experiments using vir gene-activated bacteria sprayed onto tobacco plantlets demonstrated that cells in unwounded plants could also be efficiently transformed. The condition of the plant cells was monitored using [beta]-glucuronidase under the control of a wound-inducible promoter. Infection of leaf tissue is light dependent, and it is drastically reduced when abscisic acid is exogenously applied to the plant. Under these experimental conditions, stomatal opening seems to be used by Agrobacterium to circumvent the physical barrier of the cuticle. These results thus show that the proposed cellular responses evoked by wounding in higher plants are not essential for Agrobacterium-mediated transformation.
根癌土壤杆菌通过一种导致植物肿瘤发生的基因转移机制定殖于植物细胞。毒性（vir）基因在细菌中被伤口部位释放的植物代谢产物转录激活。因此，人们认为根癌土壤杆菌利用伤口来促进其进入宿主植物，并且受伤状态是植物细胞对根癌土壤杆菌介导的基因传递具有感受态所必需的。然而，我们将激活了vir基因的细菌喷洒到烟草幼苗上的实验表明，未受伤植物的细胞也能被高效转化。使用受伤口诱导型启动子控制的β-葡萄糖醛酸酶监测植物细胞的状态。叶片组织的感染依赖于光照，当向植物外源施加脱落酸时，感染会大幅减少。在这些实验条件下，根癌土壤杆菌似乎利用气孔开放来绕过角质层的物理屏障。因此，这些结果表明，高等植物中由伤口引发的拟细胞反应对于根癌土壤杆菌介导的转化并非必不可少。
