Cheng Xu, Etalo Desalegn W, van de Mortel Judith E, Dekkers Ester, Nguyen Linh, Medema Marnix H, Raaijmakers Jos M
Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands.
Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, Wageningen 6708 PB, The Netherlands.
Environ Microbiol. 2017 Nov;19(11):4638-4656. doi: 10.1111/1462-2920.13927. Epub 2017 Nov 2.
Pseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf.SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf.SS101. Untargeted, genome-wide analyses of 7488 random transposon mutants of Pf.SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site-directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd, the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf.SS101.
荧光假单胞菌菌株SS101（Pf.SS101）可促进拟南芥生长，增强其绿化和侧根形成，并诱导对细菌病原体丁香假单胞菌番茄致病变种（Pst）的系统抗性（ISR）。在此，采用靶向和非靶向方法来鉴定Pf.SS101促进植物生长和诱导ISR所涉及的细菌决定因素及潜在机制。基于靶向分析，未发现Pf.SS101促进植物生长过程中存在挥发性物质、脂肽和铁载体的证据。对Pf.SS101的7488个随机转座子突变体进行全基因组非靶向分析，鉴定出21个在促进植物生长和诱导ISR方面均有缺陷的突变体。然而，这些突变体中的许多都是营养缺陷型，且在根部定殖方面存在缺陷。对三个突变体进行遗传分析，随后进行定点诱变、遗传互补和植物生物测定，结果表明6-磷酸葡萄糖脱水酶基因edd、响应调节基因colR和腺苷硫酸还原酶基因cysH参与了促进植物生长和诱导ISR的过程。随后的比较植物转录组学分析强烈表明，拟南芥中硫同化、生长素生物合成和运输、类固醇生物合成以及碳水化合物代谢的调节是与Pf.SS101促进生长和诱导ISR相关的关键机制。
