Marker based monitoring for virulence distribution of Pseudomonas syringae pv. tomato causing bacterial speck diseased of tomato in Egypt

Abstract The bacterial pathogen Pseudomonas syringae pv. tomato is the most important pathogen causing bacterial speck disease of tomato. Present study was conducted to investigate and characterize the population diversity of Pseudomonas syringae pv. tomato pathogen collected from infected tomato growing regions of Egypt. Significant variation was observed among the five isolates which showed significant level of virulence. Genetic variation among the isolates was investigated by PCR approach for the amplification of hrpZ gene using random amplified polymorphic DNA (RLFP), sequence-related amplified polymorphism (SRAP), and inters simple sequence repeats (ISSR). The length of amplified product for ITS1 region was 810 bp whereas for hrpZ gene was 536bp with primer pairs (1406-f/23S-r) and (MM5-F, MM5-R) respectively. The restriction analysis of amplified regions “ITS” and hrpZ by using 5 and 4 endonucleases respectively, showed slight variation among the bacterial isolates. The results of RAPD, ISSR and SRAP showed higher polymorphism (60.52%) between the isolates which assist for their successful characterization by unique and specific positive markers, based on geographical distribution, origin and virulence intensity. The results of this study suggested that the use of molecular approach can provide successful and valuable information for differentiation and classification of Pseudomonas syringae pv. tomato in future.