Studies on Bacterial Leaf Blight of Rice caused by Xanthomonas oryzae pv oryzae

Abstract

newline Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is considered as one of the most destructive diseases of rice in all over the rice growing regions of India. Investigation was conducted regarding the prevalence of Xoo pathotypes in the Basmati growing areas of Jammu subtropics, during 2019-2020. Based on morpho-cultural, biochemical and molecular characteristics, twenty Xoo isolates were collected from different Basmati cultivars, and their pathogenicity was proved on five most BLB susceptible rice cultivars viz., Basmati-370, Pusa-1121, TN-1, SJR-5 and Jaya by leaf clipping method. Seven Xoo pathotypes viz., Pathotype 1, Pathotype 2, Pathotype 3, Pathotype 4. Pathotype 5, Pathotype 6 and Pathotype 7 were identified during the course of study. Pathotype 2 was the most dominant (100%) followed by Pathotype 5 (44.44%), Pathotype 4 (40%), Pathotype 6 (40%), Pathotype 7 (33.33%), Pathotype 3 (22.22%) and Pathotype 1 (20%), in Jammu sub-tropics. In Jammu district, Pathotype 5 was highly distributed (44.44%), followed by Pathotype 7 (33.33%) and Pathotype 3 (22.22%). Pathotype 4 and Pathotype 6, each showed 40 per cent distribution in Kathua district, followed by Pathotype 1 (20%). From Samba district only Pathotype 2 was recorded, with 100 per cent distribution. Five genes viz., Xa1, Xa3, Xa10, Xa11 and Xa4+Xa13 showed complete resistance, whereas, Xa4, Xa5, Xa7, Xa8, Xa21, Xa4+Xa5 and Xa4+Xa21 showed susceptible response against the test isolates of Xoo. Highest value of virulence complexity of 11 was reported in Pathotype 5 and Pathotype 4, followed by 10 in Pathotype 7, 9 in Pathotype 6 and Pathotype 1, 7 in Pathotype 3 and 6 in Pathotype 2. newlineThe influence of minimum and maximum temperatures, morning and evening relative humidity, rainfall and sunshine on the development of bacterial leaf blight (BLB) of rice in cv. Basmati-370, caused by Xanthomonas oryzae pv. oryzae (Xoo) was investigated, under field conditions during kharif season of 2019-20 and 2020-21. BLB severity of