Development of a loop-mediated isothermal amplification (LAMP) assay for the detection of Xanthomonas translucens pv. undulosa, the bacterial leaf streak pathogen of wheat and barley

The bacterial pathogen Xanthomonas translucens pathovar (pv.) undulosa (Xtu) causes bacterial leaf streak (BLS) in wheat, barley, and triticale. In recent years, BLS has become an increasing concern in Canada. Effective disease management relies on rapid and accurate diagnostic methods for species and pathovar identification. This study describes the development of a loop-mediated isothermal amplification (LAMP) assay for the detection of Xtu from field samples. Sequence analysis and validation on multiple bacterial strains confirmed that the LAMP assay is highly specific to Xtu and universally detects diverse Xtu strains. Sensitivity testing with serial dilutions of Xtu DNA demonstrated a detection limit of 2 pg of DNA per 20-µL reaction, comparable to a previously published probe-based qPCR assay. The LAMP assay was applied to 22 wheat and barley field samples from Alberta, yielding results consistent with the qPCR assay. This is the first LAMP method capable of specifically detecting Xtu and differentiating it from closely related X. translucens pathovars, including pv. translucens and pv. graminis.