Robinette D, Matthysse A G
Department of Biology, University of North Carolina, Chapel Hill 27599.
J Bacteriol. 1990 Oct;172(10):5742-9. doi: 10.1128/jb.172.10.5742-5749.1990.
Injection into tobacco leaves of biotype 1 Agrobacterium tumefaciens or of Pseudomonas savastanoi inhibited the development of a visible hypersensitive response to the subsequent injection at the same site of Pseudomonas syringae pv. phaseolicola. This interference with the hypersensitive response was not seen with injection of bacterial growth medium or Escherichia coli cells. Live A. tumefaciens cells were required for the inhibitory effect. Various mutants and strains of A. tumefaciens were examined to determine the genes involved. Known chromosomal mutations generally had no effect on the ability of A. tumefaciens to inhibit the hypersensitive response, except for chvB mutants which showed a reduced (but still significant) inhibition of the hypersensitive response. Ti plasmid genes appeared to be required for the inhibition of the hypersensitive response. The bacteria did not need to be virulent in order to inhibit the hypersensitive response. Deletion of the vir region from pTi had no effect on the inhibition. However, the T region of the Ti plasmid was required for inhibition. Studies of transposon mutants suggested that the tms but not tmr or ocs genes were required. These genes were not acting after transfer to plant cells since they were effective in strains lacking vir genes and thus unable to transfer DNA to plant cells. The results suggest that the expression of the tms genes in the bacteria may inhibit the development of the hypersensitive response by the plant. An examination of the genes required in P. savastanoi for the inhibition of the hypersensitive response suggested that bacterial production of auxin was also required for the inhibition of the hypersensitive response by these bacteria.
将生物型1的根癌农杆菌或丁香假单胞菌注射到烟草叶片中，会抑制烟草叶片对随后在同一部位注射菜豆假单胞菌丁香致病变种产生明显的过敏反应。而注射细菌生长培养基或大肠杆菌细胞则不会出现这种对过敏反应的干扰。抑制作用需要活的根癌农杆菌细胞。研究了根癌农杆菌的各种突变体和菌株，以确定其中涉及的基因。已知的染色体突变通常对根癌农杆菌抑制过敏反应的能力没有影响，但chvB突变体对过敏反应的抑制作用有所降低（但仍很显著）。抑制过敏反应似乎需要Ti质粒基因。细菌不需要具有毒性就能抑制过敏反应。从pTi上缺失vir区域对抑制作用没有影响。然而，Ti质粒的T区域是抑制作用所必需的。对转座子突变体的研究表明，需要tms基因而非tmr或ocs基因。由于这些基因在缺乏vir基因因而无法将DNA转移到植物细胞的菌株中也有效，所以它们不是在转移到植物细胞后才起作用。结果表明，细菌中tms基因的表达可能会抑制植物过敏反应的发生。对丁香假单胞菌抑制过敏反应所需基因的研究表明，这些细菌抑制过敏反应也需要产生生长素。
