Signalling potential of iron in plant—microbe interactions: the pathogenic switch of iron transport in Erwinia chrysanthemi
Signalling potential of iron in plant—microbe interactions: the pathogenic switch of iron transport in Erwinia chrysanthemi
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铁在植物-微生物相互作用中的信号潜力：菊欧文氏菌中铁转运的致病开关
DOI：
10.1046/j.1365-313x.1995.07010121.x
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发表时间：
1995
期刊：
影响因子：
7.2
通讯作者：
D. Expert
中科院分区：
文献类型：
--
作者：
C. Masclaux;D. Expert
虽然铁的竞争在细菌毒力和动物宿主防御中早已被认识到，但它在植物致病机理中的作用最近才被阐明，软腐病病原体欧文氏菌。一个功能性的遗传系统编码的铁载体chrysobactin的生产和利用是必需的非洲紫罗兰和chrysobactin的症状扩展已被检测到在24小时的患病组织。还确定了代表该系统的fct cbs操纵子的转录活性，其编码转运和生物合成功能，受铁负调控。在这项研究中，大肠杆菌lacZ被用作报告基因来分析在感染开始时该操纵子的表达。一系列的fct：：lac染色体融合铁调节构建和一个工程菌株的行为进行了分析，在植物中，诱导LacZ活性出现后10小时叶接种，并随时间的变化，典型的调节反应铁。与亲本细胞相反，工程化细胞因此破坏了金杆菌素的生产和利用，引起了与活菌计数下降相关的坏死前沿。这些数据，第一次，提供了直接的证据，在体内调节铁控制的功能与致病性和证明（i）的表达的金杆菌介导的铁吸收系统大大有助于侵入性生长的病原体，和（ii）植物细胞外液可以检测到病原体作为铁有限的环境。
Although competition for iron has long been recognized in bacterial virulence and animal host defence, its role in plant pathogenesis has only been clarified recently, with the soft rot pathogen Erwinia chrysanthemi. A functional genetic system encoding the production and utilization of the siderophore chrysobactin is required for symptom expansion on African violets and chrysobactin has been detected in 24-h old diseased tissues. It was also established that the transcriptional activity of the fct cbs operon representative of this system, encoding transport and biosynthetic functions, is negatively regulated by iron. In this study, Escherichia coli lacZ was used as a reporter gene to analyse the expression of this operon at the onset of infection. A series of fct::lac chromosomal fusions regulated by iron were constructed and the behaviour of one engineered strain was analysed in planta; induction of LacZ activity appeared to occur after 10 h following leaf inoculation and to be subject to variations over time typical of the regulatory response to iron. In contrast to parental cells, engineered cells thus disrupted in the production and utilization of chrysobactin gave rise to a necrotic front associated with a downshift in viable counts. These data, for the first time, provide direct evidence of in vivo regulation of an iron-controlled function associated with pathogenicity and demonstrate (i) that expression of the chrysobactin-mediated iron uptake system contributes greatly to invasive growth of the pathogen, and (ii) that plant extracellular fluids can be detected by pathogens as iron-limited environments.