Bacteriophages: A New Weapon for the Control of Bacterial Blight Disease in Rice Caused by Xanthomonas oryzae

Abstract

Xanthomonas oryzae, a bacterial pathogen causing leaf blight disease (BLB) in rice, can cause widespread disease and has caused epidemics globally, resulting in severe crop losses of 50% in Asia. The pathogen is seed-borne and is transmitted through seeds. Thus, control of BLB requires the elimination of the pathogen from seeds. Concern about environment-friendly organic production has spurred improvements in a variety of biological disease control methods, including the use of bacteriophages, against bacterial plant pathogens. The present study explored the potential of bacteriophages isolated from diseased plant leaves and soil samples in killing the bacterial pathogen in rice seeds. Eight different phages were isolated and evaluated for their bacteriolytic activity against different pathogenic X. oryzae strains. Of these, a phage designated φXOF4 killed all the pathogenic X. oryzae strains and showed the broadest host range. Transmission electron microscopy of φXOF4 revealed it to be a tailed phage with an icosahedral head. The virus was assigned to the family Siphoviridae, order Caudovirales. Seedlings raised from the seeds treated with 1 × 108 pfu/ml of φXOF4 phage displayed reduced incidence of BLB disease and complete bacterial growth inhibition. The findings indicate the potential of the φXOF4 phage as a potential biological control agent against BLB disease in rice.