Physiological and biochemical characteristics of iranian strains of Xanthomonas axonopodis pv. citri, the causal agent of citrus bacterial canker disease

Twenty-four strains of Xanthomonas axonopodis pv. citri (Xac), the causal a gent of bacterial canker of citrus, isolated from Mexican lime (Citrus aura ntifolia) and lemon (Citrus limon) in southern Iran, were characterized phe notypically. Strains were all pathogenic on C. aurantifolia. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis revealed slight diffe rences in soluble protein profiles among the strains. Based on host range s pecificity and phenotypic characteristics, representative strains were diff erentiated into two groups of Asiatic (A) and atypical Asiatic (aA) forms. DNA fingerprinting analysis using EcoRI as the restriction endonuclease sho wed a negligible difference in restriction pattern between the two groups. On the basis of isozymic analysis, the two groups were distinct with respec t to superoxide dismutase (SOD) and esterase (EST) banding patterns. Plasmi d DNA profile analysis showed that the bacterial strains were different fro m each other in terms of plasmid number and molecular weight. Phage typing study revealed that most of group A strains were susceptible to Cp1 and/or Cp2 and some were resistant to both phage types including the strain in aA group. Bacteriocin production test indicated that there was a variation amo ng Xac strains using different indicators for each bacteriocin producer. It is concluded that the Iranian strains of Xac are heterogeneous and constit ute a subgroup(s) within the pathotype A.