Essential role of superoxide dismutase on the pathogenicity of Erwinia chrysanthemi strain 3937

Mol Plant Microbe Interact. 2001 Jun;14(6):758-67. doi: 10.1094/MPMI.2001.14.6.758.


The sodA gene from Erwinia chrysanthemi strain 3937 was cloned by functional complementation of an Escherichia coli sodA sodB mutant and sequenced. We identified a 639-bp open reading frame, which encodes a protein that is 85% identical to the E. coli manganese-containing superoxide dismutase MnSOD. Promoter elements of this gene were identified by transcriptional mapping experiments. We constructed an E. chrysanthemi deltasodA mutant by reverse genetics. The deltasodA mutation resulted in the absence of a cytoplasmic SOD, which displays the same characteristics as those of MnSOD. The deltasodA mutant was more sensitive to paraquat than the wild-type strain. This mutant could macerate potato tubers, similar to the wild-type strain. In contrast, when inoculated on African violets, the mutant produced, at most, only small necrotic lesions. If the inoculum was supplemented with the superoxide anion-scavenging metalloporphyrin MnTMPyP or purified SOD and catalase, the deltasodA mutant was able to macerate the inoculated zone. Generation of superoxide anion by African violet leaves inoculated with E. chrysanthemi was demonstrated with nitroblue tetrazolium as an indicator. Therefore, at the onset of infection, E. chrysanthemi cells encounter an oxidative environment and require active protective systems against oxidative damages such as MnSOD to overcome these types of conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Bacterial Proteins / physiology*
  • Base Sequence
  • Cloning, Molecular
  • Cytoplasm / enzymology
  • Escherichia coli
  • Gene Expression Regulation, Bacterial
  • Gene Expression Regulation, Enzymologic
  • Magnoliopsida / microbiology*
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Pectobacterium chrysanthemi / enzymology*
  • Pectobacterium chrysanthemi / genetics
  • Pectobacterium chrysanthemi / pathogenicity*
  • Plant Diseases / genetics
  • Plant Diseases / microbiology*
  • Recombinant Proteins / biosynthesis
  • Superoxide Dismutase / genetics*
  • Superoxide Dismutase / metabolism
  • Superoxide Dismutase / physiology*


  • Bacterial Proteins
  • Recombinant Proteins
  • SodA protein, Bacteria
  • Superoxide Dismutase