The Phytopathogen Pseudomonas syringae pv. tomato DC3000 Has Three High-Affinity Iron-Scavenging Systems Functional under Iron Limitation Conditions but Dispensable for Pathogenesis
Open Access
- 1 June 2011
- journal article
- research article
- Published by American Society for Microbiology in Journal of Bacteriology
- Vol. 193 (11), 2767-2775
- https://doi.org/10.1128/jb.00069-10
Abstract
High-affinity iron scavenging through the use of siderophores is a well-established virulence determinant in mammalian pathogenesis. However, few examples have been reported for plant pathogens. Here, we use a genetic approach to investigate the role of siderophores in Pseudomonas syringae pv. tomato DC3000 (DC3000) virulence in tomato. DC3000, an agronomically important pathogen, has two known siderophores for high-affinity iron scavenging, yersiniabactin and pyoverdin, and we uncover a third siderophore, citrate, required for growth when iron is limiting. Though growth of a DC3000 triple mutant unable to either synthesize or import these siderophores is severely restricted in iron-limited culture, it is fully pathogenic. One explanation for this phenotype is that the DC3000 triple mutant is able to directly pirate plant iron compounds such as heme/hemin or iron-nicotianamine, and our data indicate that DC3000 can import iron-nicotianamine with high affinity. However, an alternative explanation, supported by data from others, is that the pathogenic environment of DC3000 (i.e., leaf apoplast) is not iron limited but is iron replete, with available iron of >1 μM. Growth of the triple mutant in culture is restored to wild-type levels by supplementation with a variety of iron chelates at >1 μM, including iron(III) dicitrate, a dominant chelate of the leaf apoplast. This suggests that lower-affinity iron import would be sufficient for DC3000 iron nutrition in planta and is in sharp contrast to the high-affinity iron-scavenging mechanisms required in mammalian pathogenesis.Keywords
This publication has 61 references indexed in Scilit:
- Impact of Siderophore Production by Pseudomonas syringae pv. syringae 22d/93 on Epiphytic Fitness and Biocontrol Activity against Pseudomonas syringae pv. glycinea 1a/96Applied and Environmental Microbiology, 2010
- The Siderophore Pyoverdine of Pseudomonas syringae pv. tabaci 6605 Is an Intrinsic Virulence Factor in Host Tobacco InfectionJournal of Bacteriology, 2010
- Analysis of Achromobactin Biosynthesis byPseudomonas syringaepv. syringae B728aJournal of Bacteriology, 2009
- Microbial Siderophores Exert a Subtle Role in Arabidopsis during Infection by Manipulating the Immune Response and the Iron StatusPlant Physiology, 2009
- Effect of Iron Concentration on the Growth Rate of Pseudomonas syringae and the Expression of Virulence Factors in hrp -Inducing Minimal MediumApplied and Environmental Microbiology, 2009
- Iron availability and infectionBiochimica et Biophysica Acta (BBA) - General Subjects, 2008
- Salicylic Acid, Yersiniabactin, and Pyoverdin Production by the Model PhytopathogenPseudomonas syringaepv. tomato DC3000: Synthesis, Regulation, and Impact on Tomato andArabidopsisHost PlantsJournal of Bacteriology, 2007
- Modification of Leaf Apoplastic pH in Relation to Stomatal Sensitivity to Root-Sourced Abscisic Acid SignalsPlant Physiology, 2006
- FlhF Is Required for Swimming and Swarming in Pseudomonas aeruginosaJournal of Bacteriology, 2006
- NPS6, Encoding a Nonribosomal Peptide Synthetase Involved in Siderophore-Mediated Iron Metabolism, Is a Conserved Virulence Determinant of Plant Pathogenic AscomycetesPlant Cell, 2006