Ketahanan genotipe padi terhadap Xanthomonas oryzae pv. oryzae patotipe III, IV, dan VIII

anglais. Testing of resistance to dominant BLB pathotypes of Xanthomonas oryzae pv. oryzae (Xoo) bacterium were carried out on 22 IRBB isogenic lines (IL), 22 local varieties (LV), 6 new varieties (NV), one differential variety, and 49 F1 crosses of IL with NV, IL with local varieties or LV with NV The study was conducted in the screened field of Indonesian Center for Rice Research in Sukamandi during the Dry Season of 2010 and Wet Season of 2010/ 2011. Each of the experiments was arranged in a randomized block design with three replications. Three dominant pathotypes of Xoo were tested, i.e. pathotype III, IV, and VIII. The results showed that for Xoo pathotype III, there were three ILs reacted moderately resistant (MR), 18 lines moderately susceptible (MS), one line susceptible (S), 15 local varieties resistant (R) and 7 MR

4 new varieties were R and one new variety was MR, while 48 F1 were R and one F1 line was R. Reactions of the rice genotypes to Xoo pathotype IV indicated two isogenic lines were MR, 20 isogenic lines were S, four local varieties were MS and 18 varieties were S, 6 F1 lines were MR, one F1 line was MS, 38 F1 were line Sand 4 F1 line highly susceptible (HS), one new variety was MS, four new varieties were S, and one new variety was HS. Resistance to pathotype IV was a complex trait that needs specific genetic combination. Reactions of rice genotypes to Xoo pathotype VIII showed 14 isogenic lines were MS and 8 were S

5 local varieties were MR, 10 were S, and 7 were S

16 F1 lines were R, 25 F1 lines were MR, and 8 F1 lines were MS. IRBB10 (Xa10) and IRBB64 (Xa4 + xa5 + Xa7 + Xa21) were each more resistant to Xoo pathotypes III, IV, and VIII than the other isogenic lines. The differential variety Java 14 (Xa 1, xa3, Xa 12) showed MR reaction to Xoo pathotypes III, IV and VIII, and was potential to be used as a donor parent in breeding for broad spectrum resistance to BLB.