Specificity of Multiplex PCR in the Detection of Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola in Rice (Oryza sativa L.) Seeds

Abstract

One of the major hurdles faced by numerous quarantine centers is to accurately detect and distinguish non-plant pathogenic bacteria from plant pathogenic bacteria based on colony morphology. Yellow colony-forming, non-plant pathogenic bacteria found in rice seeds are often misidentified as Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc), causal agents of bacterial leaf blight and bacterial leaf streak, respectively. In this study, 51 non-pathogenic, yellow-colony forming, Xoo and Xoc look-alike bacteria isolated from rice seeds, were used to test the specificity of a multiplex PCR for the detection and differentiation of Xoo and Xoc. Four primer pairs used in this multiplex PCR specific for Xanthomonas oryzae (Xo), Xoo and Xoc were used and all 51 isolates did not amplify any band, indicating that they are not Xo, Xoo or Xoc. These results imply that the multiplex PCR used in this study is robust in detecting and differentiating Xoo and Xoc from non-pathogenic, rice seed-associated, yellow colony-forming bacteria.