Departamento de Microbiología y Genética, Edificio Departamental de Biología, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain.
Syst Appl Microbiol. 2010 Aug;33(5):247-51. doi: 10.1016/j.syapm.2010.04.004.
Some strains of the former genus Agrobacterium have high biotechnological interest and are currently misclassified. Consequently, in this study, the taxonomic status of the non-pathogenic strain Agrobacterium radiobacter K84, used in biological control, and the tumourigenic strain Agrobacterium tumefaciens AKE10, able to regenerate tobacco transgenic plants, was revised. The phylogenetic analysis of the chromosomal genes rrs, atpD and recA showed that they should be reclassified into Rhizobium rhizogenes. The analysis of virulence genes located in the Ti plasmid (pTi) outside T-DNA showed a common phylogenetic origin among strains AKE10, R. rhizogenes 163C and A. tumefaciens (currently R. radiobacter) C58. However, the genes located inside the T-DNA, mainly the 6b gene, of strain AKE10 were phylogenetically close to those of strain 163C but divergent from those of strain C58. Furthermore, the T-DNA of tumourigenic strains from R. rhizogenes conferred on them the ability to regenerate tumour tissue resembling fasciation in tobacco plants. These results showed the existence of a highly mosaic genetic organization in tumourigenic strains of the genus Rhizobium and provided evidence of the involvement of T-DNA from tumourigenic strains of R. rhizogenes in fasciation of Nicotiana leaves. The data further suggested that pathogenic strains of Rhizobium could be good models to analyse bacterial evolution.
一些前属农杆菌菌株具有很高的生物技术兴趣，但目前被错误分类。因此，在这项研究中，我们修订了用于生物防治的非致病性菌株根癌农杆菌 K84 和能够再生烟草转基因植物的致瘤菌株根癌农杆菌 AKE10 的分类地位。染色体基因 rrs、atpD 和 recA 的系统发育分析表明，它们应重新归类为根瘤菌。位于 Ti 质粒（pTi）而非 T-DNA 中的毒力基因分析表明，AKE10 菌株、根瘤菌 163C 和根癌农杆菌（现为根瘤菌 radiobacter）C58 之间存在共同的进化起源。然而，AKE10 菌株中位于 T-DNA 内的基因，主要是 6b 基因，与 163C 菌株的基因在系统发育上接近，但与 C58 菌株的基因不同。此外，根瘤菌属致瘤菌株的 T-DNA 赋予它们在烟草植物中再生类似于畸形的肿瘤组织的能力。这些结果表明，根瘤菌属致瘤菌株中存在高度镶嵌的遗传组织，并为根瘤菌属致瘤菌株的 T-DNA 参与烟草原生质体的畸形提供了证据。这些数据进一步表明，根瘤菌的致病性菌株可以成为分析细菌进化的良好模型。
