Evaluation of resistance in some rice cultivars to bacterial blight disease caused by Xanthomonas oryzae pv. oryzae

Background and Objectives Bacterial leaf blight of rice, caused by Xanthomonas oryzae pv. Oryzae, is a destructive bacterial disease of rice in growing regions of this plant worldwide. Although the application of chemicals significantly reduces plant diseases, planting resistant cultivars remains the most effective strategy to control crop diseases. This study aims to evaluate the resistance of four rice cultivars Hashemi, Lenjan, Firuzan and Gilane to bacterial blight, under growth chamber conditions. Materials and Methods The population growth and symptom development were monitored after introduction of bacterial suspensions (107 cfu ml–1) into leaf intercellular spaces. In this investigation, the effects of Xanthomonas oryzae pv. oryzae stress on the activity of superoxide dismutase, catalase and peroxidase in different rice leaves were evaluated. Antioxidant assays were performed with leaf samples collected on 4th day after infection (4th DAI), 8th DAI and 12th DAI. Results After infiltration of different cultivars with the bacterium, the highest populations were detected in Hashemi cultivar, followed by Gilane and Firuzan cultivars 14 and 16 days after infiltration. At 12th DAI, the higher peroxidase activity was observed in Lenjan cultivar. At 12th DAI, the activity of superoxide dismutase was increased 33.3, 23.5, 15.5 and 33.3 percent, respectively, in Lenjan, Gilane, Hashemi and Firuzan cultivars compared to the control. Discussion The present study showed that based on the population dynamics of Xanthomonas oryzae pv. oryzae in different rice leaves, pathogenicity (percentage of necrotic area per leaf) and antioxidant activity, Hashemi was the most susceptible cultivar and Lenjan was the most resistant cultivar to bacterial blight.