Pengujian ketahanan 22 galur padi isogenik (IRBB), 22 varietas lokal, 6 varietas unggul baru (VUB), satu varietas diferensial, dan 49 galur F1 hasil persilangan dari galur inbrida (GI) dengan VUB serta GI dengan varietas lokal dan varietas lokal dengan VUB terhadap HDB [Xanthomonas oryzae pv. oryzae (Xoo) patotipe III, IV, dan VIII] telah dilakukan secara terpisah di rumah kasa Balai Besar Penelitian Padi di Sukamandi pada Musim tanam (MT) I dan MT II tahun 2010. Masing-masing percobaan ditata dalam rancangan acak kelompok dengan tiga ulangan. Hasil pengujian terhadap patotipe III menunjukkan bahwa tiga galur IRBB bereaksi agak tahan (AT),18 galur agak rentan, dan satu galur rentan; 15 varietas lokal bereaksi tahan dan tujuh varietas agak tahan; empat VUB tahan, dan satu varietas agak tahan, sedangkan 48 galur F1 tahan dan satu galur agak tahan. Reaksi terhadap Xoo patotipe IV menunjukkan bahwa dua galur IRBB agak rentan dan 20 galur rentan; empat varietas lokal bereaksi agak rentan, dan 18 varietas rentan; enam galur F1 bereaksi agak tahan dan satu galur agak rentan, 38 galur rentan, dan empat galur sangat rentan. Satu VUB bereaksi agak rentan, empat rentan dan satu sangat rentan. Ketahanan terhadap Xoo patotipe IV bersifat kompleks dan memerlukan kombinasi genetik spesifik. Empat belas galur IRBB agak rentan dan delapan galur rentan, lima varietas lokal agak tahan, 10 varietas lokal agak rentan, dan tujuh varietas lokal rentan, 16 F1 tahan, 25 F1 agak tahan, dan delapan F1 agak rentan terhadap Xoo patotipe VIII. Galur IRBB10 (Xa10) dan IRBB64 (Xa4+xa5+Xa7+Xa21) relatif tahan terhadap HDB strain III, IV, dan VIII dibanding materi genetik lain yang diuji. Java 14 (Xa1, xa3, Xa12), salah satu varietas padi diferensial, agak tahan terhadap Xoo patotipe III, IV dan VIII, dan potensial digunakan sebagai tetua donor dalam perakitan padi tahan HDB berspektrum luas.
Rice Genotypes Resistant to Xanthomonas oryzae pv. oryzae Pathotypes III, IV, and VIII. 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 S and 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 defferential variety Java 14 (Xa1, xa3, Xa12) 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.
