Pathogenic variability in Xanthomonas oryzae pv oryzae in Bangladesh

Pathogenic variability of 40 isolates of Xanthomonas oryzae pv oryzae obtai ned from flag leaf samples of bacterial leaf blight in rice (oryza sativa L .) collected from different districts in Bangladesh was studied. The pathog enic variability was tested on to seedlings of the five differential variet ies of rice, viz 'BR 14','Iratom 24','TKM 6',BR 3' and 'BR 9'. Twelve races of Xanthomonas oryzae pv oryzae were identified in different districts in Bangladesh. Among the races, the race 11 was commonly distributed in the di stricts Comilla, Mymensingh, Bogra and Gazipur followed by race 12 which wa s common in the districts Dhaka, Mymensingh and Gazipur. The most frequentl y occurring race was race 7 followed by race 11. Flag leaf inoculation test s on a susceptible cultivar 'BR 9' and a moderately resistant cultivar 'BR 14' revealed that there were six and seven virulence groups of Xanthomonas oryzae pv oryzae respectively, existing in Bangladesh.