RpoN (sigma54) controls production of antifungal compounds and biocontrol activity in Pseudomonas fluorescens CHA0.
RpoN (sigma54) controls production of antifungal compounds and biocontrol activity in Pseudomonas fluorescens CHA0.
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DOI：
10.1094/mpmi-18-0260
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发表时间：
2005-03
期刊：
影响因子：
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通讯作者：
Maria Péchy-Tarr;M. Bottiglieri;S. Mathys;K. Lejbølle;U. Schnider-Keel;M. Maurhofer;C. Keel
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文献类型：
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作者：
Maria Péchy-Tarr;M. Bottiglieri;S. Mathys;K. Lejbølle;U. Schnider-Keel;M. Maurhofer;C. Keel
荧光假单胞菌（PseudomonasfluorescensCHA 0）是一种有效的植物根病生防菌。该菌株产生抗生素2，4-二乙酰基间苯三酚（DAPG）和苯丙酮酸（PLT），对病原体抑制做出重要贡献。本研究集中于sigma因子RpoN（sigma 54）在荧光假单胞菌中的抗生素产生和生防活性的调节中的作用。CHAO的rpoN框内缺失突变体具有生长延迟，对多种碳源和氮源的利用受损，并且对盐胁迫更敏感。的rpoN突变体是有缺陷的鞭毛，并显示大幅减少游泳和群集motilities。有趣的是，与野生型和补充有单拷贝rpoN+的突变体相比，rpoN突变体显示出数倍增强的DAPG生产和生物合成基因phlA的表达。相比之下，RpoN功能的丧失导致PLT产生和plt基因表达显著降低，表明RpoN控制菌株CHA 0中两种抗生素的平衡。在自然土壤微宇宙中，rpoN突变体在保护黄瓜免受终极腐霉引起的根腐病方面效果较差。值得注意的是，突变体并没有显着损害其根定殖能力，即使在早期阶段的根感染腐霉属。两者合计，我们的研究结果首次建立RpoN作为荧光假单胞菌生物防治活性的主要调节剂。
Pseudomonas fluorescens CHA0 is an effective biocontrol agent of root diseases caused by fungal pathogens. The strain produces the antibiotics 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT) that make essential contributions to pathogen suppression. This study focused on the role of the sigma factor RpoN (sigma54) in regulation of antibiotic production and biocontrol activity in P. fluorescens. An rpoN in-frame-deletion mutant of CHAO had a delayed growth, was impaired in the utilization of several carbon and nitrogen sources, and was more sensitive to salt stress. The rpoN mutant was defective for flagella and displayed drastically reduced swimming and swarming motilities. Interestingly, the rpoN mutant showed a severalfold enhanced production of DAPG and expression of the biosynthetic gene phlA compared with the wild type and the mutant complemented with monocopy rpoN+. By contrast, loss of RpoN function resulted in markedly lowered PLT production and plt gene expression, suggesting that RpoN controls the balance of the two antibiotics in strain CHA0. In natural soil microcosms, the rpoN mutant was less effective in protecting cucumber from a root rot caused by Pythium ultimum. Remarkably, the mutant was not significantly impaired in its root colonization capacity, even at early stages of root infection by Pythium spp. Taken together, our results establish RpoN for the first time as a major regulator of biocontrol activity in Pseudomonas fluorescens.