Resistance of Doubled Haploid Rice Lines to Bacterial Leaf Blight (Xanthomonas oryzae pv. oryzae)

Developing new high-yielding rice varieties resistant to bacterial leaf blight (BLB) is an effective strategy for controlling BLB. Several advanced doubled haploid rice lines derived from anther culture previously selected need assessment for BLB resistance. This study aimed to evaluate the resistance of these lines to BLB pathotypes III, IV, and VIII in the vegetative and generative phases. The experiment took place in a greenhouse using 16 rice genotypes comprising 12 doubled haploid rice lines, two commercial check varieties (Inpari 18 and Inpari 34), and a BLB-resistant and susceptible check variety (Code and TN-1, respectively). Inoculation began with the leaf clipping method using a suspension of the pathogen Xanthomonas oryzae pv. oryzae (Xoo) at a concentration of 109 cfu/ml. The results indicated significant influences on disease severity and intensity of BLB of pathotype, genotype, and the interactions between pathotype and genotype, finding their values higher in the vegetative phase. Six doubled haploid lines ranged from resistant to moderately resistant (disease severity 2.0%–10.7%, disease intensity 6.7%–36.8%) to pathotypes III and IV in two growth phases, i.e., HS1-35-1-4, HS4-15-1-9, HS4-15-1-16, HS4-15-1-24, HS4-15-1-26, and HS4-15-1-28. All those doubled haploid lines were susceptible to BLB pathotype VIII in the vegetative phase and moderately susceptible in the generative phase.