EN
Pseudomonas syringae pv. syringae is a plant pathogen bacterium in rice which causes bacterial sheath rot. In this study, simplified AFLP (Amplified fragment length polymorphism) was tested in order to evaluate genetic diversity of 38 Pseudomonas syringae pv. syringae strains isolated from rice fields of the Guilan province, by 12 AFLP primers. The products resulted from AFLP were separated using agarose gel electrophoresis. The maximum number of PIC among all tested primers belonged to primer 36. Based on the Unweighted Pair Group Method with Arithmetic (UPGMA) method, using NTSISpc Software, all Pseudomonas syringae pv. syringae strains were divided into three distinct clusters which had a 70% similarity level. Cluster analysis of studied populations (isolates of fields, panicles, and nurseries) determined that a high genetic identity could be seen among isolates obtained from the panicles and nurseries, while strains isolated from the fields and nurseries had the most genetic distance with each other. The result of this study showed that sampling site and weather conditions play an important role in genetic evolution of strains. It was also found that AFLP is an effective marker in evaluating genetic diversity within and among isolates being studied, while all of them had the same host and pathogenesis characteristics.