Virulence of Xanthomonas campestris pv. oryzae isolated in indonesia and bangladesh.

Abstract

Forty isolates of Xanthomonas campestris pv. oryzae collected from naturally infected rices in various areas of West Java in Indonesia were evaluated for their virulence to differential varieties of Japan and IRRI. Of 40 isolates in Indonesia, 36 were virulent to Kinmaze, Kogyoku, and Te-tep but avirulent to Wase Aikoku 3 and Java 14. Of 40 isolates of X. campestris pv. oryzae tested, 25 were judged to belong to group A which was identical with the Philippine bacterial group III in terms of virulence. Groups B and C had 6 and 2 isolates, respectively, which were identical with the Philippine bacterial groups I and IV. Two isolates belonging to group I showed a similar virulence to the Japanese bacterial group V and one isolate in group F was apparently similar to the Japanese bacterial group III. Majority of the isolates tested were virulent to IR20 which had a dominant resistance gene, Xa-4, which was same as that of IR36. Therefore, severe outbreak of the disease on IR36 in Indonesia is probably due to occurrence of race which is same as the Philippine bacterial group III. Twenty isolates from Bangladesh were also evaluated for their virulence patterns to the differential varieties. Based on the reaction patterns of the 10 differential varieties of Japan and IRRI, 4 isolates fell under the same bacterial group that was virulent to Kinmaze, Kogyoku, IR8, IR20, IR1545-339, DV85, and Cas 209 but avirulent to Te-tep, Wase Aikoku 3, and Java 14. Similarly, 2 isolates were found to belong to another group that was virulent to Kinmaze, IR8, IR1545-339, DV85, and Cas 209. The virulence patterns of the 2 groups were different from those of any other groups so far reported. The other Bangladesh isolates showed intermediate reactions to differential varieties.