A Siderophore Analog of Fimsbactin from Acinetobacter Hinders Growth of the Phytopathogen Pseudomonas syringae and Induces Systemic Priming of Immunity in Arabidopsis thaliana

Fabrice Betoudji,Manuka Ghosh,Marvin J Miller,Kamal Bouarab,Taha Abd El Rahman,Mario Jacques,François Malouin

doi:10.3390/pathogens9100806

Fabrice Betoudji, Manuka Ghosh + Show 5 more

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https://doi.org/10.3390/pathogens9100806

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Abstract

Siderophores produced in soil by plant growth-promoting rhizobacteria (PGPRs) play several roles, including nutrient mobilizers and can be useful as plants defense elicitors. We investigated the role of a synthetic mixed ligand bis-catechol-mono-hydroxamate siderophore (SID) that mimics the chemical structure of a natural siderophore, fimsbactin, produced by Acinetobacter spp. in the resistance against the phytopathogen Pseudomonas syringae pv tomato DC3000 (Pst DC3000), in Arabidopsis thaliana. We first tested the antibacterial activity of SID against Pst DC3000 in vitro. After confirming that SID had antibacterial activity against Pst DC3000, we tested whether the observed in vitro activity could translate into resistance of Arabidopsis to Pst DC3000, using bacterial loads as endpoints in a plant infection model. Furthermore, using quantitative polymerase chain reaction, we explored the molecular actors involved in the resistance of Arabidopsis induced by SID. Finally, to assure that SID would not interfere with PGPRs, we tested in vitro the influence of SID on the growth of a reference PGPR, Bacillus subtilis. We report here that SID is an antibacterial agent as well as an inducer of systemic priming of resistance in A. thaliana against Pst DC3000, and that SID can, at the same time, promote growth of a PGPR.

Highlights

With the exception of a few organisms, such as lactobacilli and Borrelia burgdorferi [1,2], virtually all living organisms, including plants, require iron for biological functions
The iron acquisition machinery in bacteria is overexpressed in iron-depleted environments [25]
The growth of bacterial pathogens may be significantly compromised if the iron acquisition machinery they express is not adequate for the environment they face

Summary

Introduction

With the exception of a few organisms, such as lactobacilli and Borrelia burgdorferi [1,2], virtually all living organisms, including plants, require iron for biological functions. Iron is required for many physiological functions, such as photosynthesis, chlorophyll biosynthesis, and respiration. The soil is the main source of iron acquisition for plants that assimilate it from their roots [3]. The third most abundant element in the earth’s crust [4], iron is paradoxically in limited quantity for plants because its availability depends on many factors, such as the pH of the soil and the redox potential [5]. Under aerobic conditions and at higher pH, iron is mainly present in its less soluble ferric oxidized form (Fe3+ ) and is not available for uptake by plants.

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