عنوان مقاله [English]
نویسندگان [English]چکیده [English]
To study the relationships among arginine dihydrolase and oxidase – positive strains of Pseudomonas associated with sheath rot of rice, the strains were characterized in parallel with three standard strains by using pathological and biochemical tests, protein fingerprints and PCR – RFLP of 16S rRNA. Cluster analysis of phenotypic characters grouped the strains into four main clusters and two single – membered groups. Comparison of fingerprints of each cluster as well as other characteristics including pathogenicity, type of tissues they were isolated from and geographical origin were used to select one or more representative strains from each clusters. Representative strains and three standard arginine dihydrolase and oxidase – positive strains of Pseudomonas were studied using the 16S rRNA – RFLP. Cluster analysis of the data produced by different restriction enzymes was used to group the strains into six distinct clusters (genotypes). Pathogenic strains were divided into four genotypes including P. marginalis and three other genotypes which were also distinct from standard strains, P. fuscovagina and P. fiuorescens. None of the strains was similar to the standard strain of P. fuscovaginae, wich is considered to be the main causal agent of sheath rot and grain discoloration of rice.