Vol. 12, Issue 9 (2023)

Author(s):
Kishan Debnath, Gopalakrishnan C, Kannan R, Kannan M and Manonmani S

Abstract:
Rice is the most important and extensively grown food crop grown in India. Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most destructive bacterial disease in different rice growing regions of India resulting in crop losses up to 50%. From the major rice growing areas of Tamil Nadu, 8 isolates of Xoo have been isolated during 2022-2023 to assess their virulence pattern. Sequencing and blast analysis confirmed that all the isolates were Xanthomonas oryzae pv. oryzae. The molecular characterisation of the isolates was carried out by PCR amplification of the hpaA gene using XOF and XOR primers, and all the isolates were amplified at 534 bp. The susceptible rice cultivar TN1 was inoculated with all the isolates, and all the isolates produced typical symptoms of BLB, including white to yellow stripes with wavy margins on the leaves. However, the severity of the disease varied significantly among them, from the most severe isolate, TNXOO1, to the least severe isolate, TNXOO8. Incorporating novel resistance genes into commercial rice cultivars is urgently needed to combat BLB due to the rising prevalence of highly virulent isolates of Xoo in Tamil Nadu.