Multiplex PCR assay for the detection of Pantoea stewartii subsp. stewartii using species-specific genetic markers

We developed a multiplex PCR detection assay for quick diagnosis of Pantoea stewartii subsp. stewartii the causal agent of Stewart’s bacterial wilt and leaf blight of maize, using specific genetic markers. The genetic markers of wtsE, cpsA and hrpN gene specifically amplified 519 bp, 375 bp and 200 bp of DNA, respectively, from all isolates of P. stewartii subsp. stewartii but not from other phytopathogenic bacteria. The sensitivity of the genetic markers is down to 10³ CFU/mL (5 cells per reaction) of bacterial culture and ~0.5 pg of genomic DNA. In sampling studies, the assay detected P. stewartii subsp. stewartii from artificially infected maize plants 12 days post inoculation. The PCR based genetic markers are specific and they give selective and sensitive amplification of P. stewartii subsp. stewartii for diagnosis in mixed cultures and in planta.