Abstract

In this study samples with stunting, chlorosis, leaf malformation and wilting symptoms from alfalfa fields in Fars province were collected an investigated in the lab. The bacterial agent was isolated, purified and identified using standard bacteriological testes. 32 strains were isolated from infected plants using NA and NBY media. The isolates were gram and catalase negative and oxidase negative and obligatory aerobic. All isolates induced hypersensitive reaction on tobacco. All strains produced acid from galactose and mannose did not produced from inulin, sorbitol, ribose, mannitol. None of the strains have been utilized sodium acetate and sodium succinate. The specific primers CMI-III/BB and CIRS1 CIRS2 were used in PCR test for final diagnosis. The isolates were able to amplify 218 bp and 132 bp DNA fragment with primer pairs CMI-III/BB1 and CMI-III/BB2 and primers pairs CIRS1 and CIRS2 in PCR test, respectively. Pathogenicity of the strains were confirmed on alfalfa plants under greenhouse condition. Based on symptoms, phenotypic characteristics and PCR test with specific primers, the bacterial isolates were identified as Clavibacter michiganensis subsp. insidiosus‎‎.