Plant flavonoids target Pseudomonas syringae pv. tomato DC3000 flagella and type III secretion system

Authors

  • Paola Vargas,

    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Gabriela A. Farias,

    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
    2. Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Joaquina Nogales,

    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Harold Prada,

    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Vivian Carvajal,

    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
    2. Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Matilde Barón,

    1. Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • Rafael Rivilla,

    1. Department of Biology, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
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  • Marta Martín,

    1. Department of Biology, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
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  • Adela Olmedilla,

    1. Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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  • María-Trinidad Gallegos

    Corresponding author
    1. Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín (EEZ-CSIC), Granada, Spain
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Summary

Flavonoids are among the most abundant plant secondary metabolites involved in plant protection against pathogens, but micro-organisms have developed resistance mechanisms to those compounds. We previously demonstrated that the MexAB-OprM efflux pump mediates resistance of Pseudomonas syringae pv. tomato (Pto) DC3000 to flavonoids, facilitating its survival and the colonization of the host. Here, we have shown that tomato plants respond to Pto infection producing flavonoids and other phenolic compounds. The effects of flavonoids on key traits of this model plant-pathogen bacterium have also been investigated observing that they reduce Pto swimming and swarming because of the loss of flagella, and also inhibited the expression and assembly of a functional type III secretion system. Those effects were more severe in a mutant lacking the MexAB-OprM pump. Our results suggest that flavonoids inhibit the function of the GacS/GacA two-component system, causing a depletion of rsmY RNA, therefore affecting the synthesis of two important virulence factors in Pto DC3000, flagella and the type III secretion system. These data provide new insights into the flavonoid role in the molecular dialog between host and pathogen.

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