Phenotypic and genotypic characterization of wheat spike blight bacterium in southern Kerman province

Twenty-one bacterial strains were isolated from wheat showing spike blight disease symptoms in southern Kerman province. Differential phenotypic features of the strains were studied using common bacteriological methods. Molecular identification of the isolates was studied by amplification and partial sequence analyses of 16S rRNA, gyrB and recA genes. PCR assays using specific primer sets amplified 700 and 558 bp amplicons of 16S rRNA and gyrB genes from all strains, respectively. PCR assay with specific primer set for recA gene amplified a 600 bp fragment from Rathayibacter iranicus, but not from R. tritici strain and the isolated strains from wheat in southern Kerman province, as well. Sequences of the amplicons obtained from each gene locus were identical to those sequences for R. tritici reference strains as well as the R. tritici strains available in GenBank. Results obtained from phenotypic tests and analyses of the data from amplification and sequencing of the studied gene loci indicated that R. tritici is the causal agent of wheat spike blight disease in southern Kerman province. To the best of our knowledge, this is the first report of R. tritici on wheat in Kerman province.