PATHOGENIC VARIABILITY AMONG DIFFERENT ISOALTES OF XANTHOMONAS AXONOPODIS PV. CITRI

Citrus production is subjected to the attack of a number of production threats. Citrus canker, caused by Xanthomonas axonopodis pv citri (Xac) is one of them. In the present study five different isolates of the bacterium (Xac) including Xac1, Xac2, Xac3, Xac4, and Xac5 isolated from grapefruit (Citrus paradesi), lime (Citrus limon), rough lemon (Citrus jambhiri), red blood malta (Citrus sinensis) and kinnow (Citrus reticulata), respectively were used. These isolates were tested to find the pathogenic variability on three test hosts including grapefruit, lime and rough lemon. The results of these isolates on pathogenicity, symptoms development and host susceptibility indicated that the isolate Xac3 showed greater virulence on all test hosts, followed by the isolate Xac4, while the response of other three isolates was intermediate. Among the test hosts, grapefruit gave the highest degree of susceptibility to all the strains, while lime and lemon were ranked second and third, respectively.The results of the study suggest variation in the pathogenic nature of these isolates.