Study on genetic diversity of Pseudomonas tolaasii and Pseudomonas reactans bacteria associated with mushroom brown blotch disease employing ERIC and BOX-PCR techniques

To distinguish the pathogenic strains of Pseudomonas tolaasii and saprophytic strains P. reactants, many mushroom cultivation centers in Iran were surveyed and samples were taken from compost, soil cover and button caps with or without visible symptoms preferably from flush two and three. Fifty five bacteria were isolated on the basis of colony morphology, pathogenicity test on excised tissue blocks of the fresh Agaricus bisporus, white line test, soft rot on potato tuber slices, erythrocytes hemolysis and certain biochemical and molecular characteristics. To confirm the identification of P. reactants strains, two strains of this group (A2 and A6) were subjected to RNA polymerase beta-subunit gene amplification analysis using primer sets of long amplicon primers LAPS and LAPS27. In total, 16 isolates of P. reactants and 15 isolates of P. tolaasii were identified and compared with standard isolates. Subsequently, genetic diversity of the isolates of each species was determined separately with general primers ERIC 1R, ERIC 2 and BOX AIR and clusters were drawn.