Llama-Palacios Arancha, López-Solanilla Emilia, Poza-Carrión César, García-Olmedo Francisco, Rodríguez-Palenzuela Pablo
Departamento de Biotecnología-UPM, E. T. S. Ingenieros Agrónomos, E-28040 Madrid, Spain.
Mol Microbiol. 2003 Jul;49(2):347-57. doi: 10.1046/j.1365-2958.2003.03583.x.
We have studied the role of acidic pH as a barrier for the colonization of the plant apoplast by Erwinia chrysanthemi. A minitransposon containing a promoterless reporter gene, gus, was used for random mutagenesis of the bacterial genome. An acid-sensitive mutant, named BT119, was isolated and had the following differential features with respect to the wild-type strain: (i) inability to grow at pH </= 5.5; (ii) decreased survival at acid pH and in plant tissues; (iii) increased susceptibility to antimicrobial peptides; (iv) decreased virulence in chicory leaves and pear fruits; (v) reduced polygalacturonase production; and (vi) reduced ability to alkalinize chicory tissues after infection. The sequence of the interrupted gene was highly similar to the phoQ gene, which is involved in environmental sensing in several bacteria, such as Yersinia pseudotuberculosis, Erwinia carotovora, Salmonella typhimurium and Escherichia coli and thus, this designation was used for the E. chrysanthemi system. This gene was induced at low Mg(2+) concentrations and in planta. These results suggest that E. chrysanthemi PhoP-PhoQ system plays an important role in bacterial survival in plant tissues during the initial infection stages.
我们研究了酸性pH作为植物溶生质体被菊欧文氏菌定殖的屏障所起的作用。一个含有无启动子报告基因gus的微型转座子被用于细菌基因组的随机诱变。分离出一个酸敏感突变体，命名为BT119，它相对于野生型菌株具有以下差异特征：（i）在pH≤5.5时无法生长；（ii）在酸性pH条件下和植物组织中的存活率降低；（iii）对抗菌肽的敏感性增加；（iv）在菊苣叶和梨果实中的毒力降低；（v）聚半乳糖醛酸酶产量减少；以及（vi）感染后使菊苣组织碱化的能力降低。中断基因的序列与phoQ基因高度相似，phoQ基因在几种细菌如假结核耶尔森菌、胡萝卜软腐欧文氏菌、鼠伤寒沙门氏菌和大肠杆菌中参与环境感知，因此，该名称用于菊欧文氏菌系统。该基因在低镁离子浓度下和植物体内被诱导。这些结果表明，菊欧文氏菌PhoP - PhoQ系统在初始感染阶段在细菌于植物组织中的存活中起重要作用。
