Open AccessImpact of Siderophore Production by Pseudomonas syringae pv. syringae 22d/93 on Epiphytic Fitness and Biocontrol Activity against Pseudomonas syringae pv. glycinea 1a/96
Author(s) -
Annette Wensing,
Sascha D. Braun,
Petra Büttner,
Dominique Expert,
Beate Völksch,
Matthias S. Ullrich,
Helge Weingart
Publication year - 2010
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.02979-09
Subject(s) - pseudomonas syringae , biology , siderophore , pseudomonadaceae , pseudomonadales , microbiology and biotechnology , pseudomonas , pathogen , bacteria , genetics
The use of naturally occurring microbial antagonists to suppress plant diseases offers a favorable alternative to classical methods of plant protection. The soybean epiphytePseudomonas syringae pv. syringae strain 22d/93 shows great potential for controllingP. syringae pv. glycinea, the causal agent of bacterial blight of soybean. Its activity againstP. syringae pv. glycinea is highly reproducible even in field trials, and the suppression mechanisms involved are of special interest. In this work we demonstrated thatP .syringae pv. syringae 22d/93 produced a significantly larger amount of siderophores than the pathogenP. syringae pv. glycinea produced. WhileP .syringae pv. syringae 22d/93 andP. syringae pv. glycinea produce the same siderophores, achromobactin and pyoverdin, the regulation of siderophore biosynthesis in the former organism is very different from that in the latter organism. The epiphytic fitness ofP .syringae pv. syringae 22d/93 mutants defective in siderophore biosynthesis was determined following spray inoculation of soybean leaves. The population size of the siderophore-negative mutantP .syringae pv. syringae strain 22d/93ΔSid was 2 orders of magnitude lower than that of the wild type 10 days after inoculation. The growth deficiency was compensated for when wound inoculation was used, indicating the availability of iron in the presence of small lesions on the leaves. Our results suggest that siderophore production has an indirect effect on the biocontrol activity ofP .syringae pv. syringae 22d/93. Although siderophore-defective mutants ofP .syringae pv. syringae 22d/93 still suppressed development of bacterial blight caused byP. syringae pv. glycinea, siderophore production enhanced the epiphytic fitness and thus the competitiveness of the antagonist.