Characterization and discrimination of citrus canker causing pathotypes in citrus trees using RAPD and ISSR markers

The present study was conducted to differentiate pathotypes of Xanthomonas citri subsp. citri (Xcc) the causal agent of citrus canker in Iran. A collection of 29 strains were isolated from infected plant parts. In order to investigate the genetic diversity of bacterial isolates, RAPD and ISSR markers were used and discrimination power of these markers for the pathotype detection was assessed. Based on the amplified fragments of the RAPD, the dendrogram divided the strains into three main groups. In the first group, there were eight strains of both pathotypes A and A*, and all strains of A* pathotype were categorized in this group. Strains of pathotype A formed the second and third groups. Based on the results of the ISSR amplified fragments, the dendrogram classified the strains into three main groups. The resultant grouping was indicative of placement of A strains in one group, and in all groups, both A and A* pathotypes were grouped together. The electrophoresis patterns of amplified fragments with RAPD primers revealed high specificity of this marker in pathotype differentiation.