A Rapid and Reliable Propidium Monoazide Polymerase Chain Reaction for Detecting Viable Pseudomonas syringae pv....

Pseudomonas syringae pv. actinidiae (Psa) is responsible for causing kiwifruit canker disease. The detection of Psa is commonly carried out using normal PCR and culture-based isolation. However, normal PCR does not differentiate between live and dead cells, potentially resulting in the incorrect estimation of the amount of infectious substance in a sample. Such an incorrect estimation could result in unnecessary phytosanitary strategies and control measures. This study attempts to establish a specific assay for detecting only live Psa bacterial cells. To achieve this, a pair of strain-specific primers designed from HopZ3 effector were used, and the traditional PCR method was assessed using a nucleic acid-binding dye (propidium monoazide-PMA), establishing a PMA-PCR system and conditions for detecting live Psa in this study. Sensitivity tests showed a detection limit of 10 cfu/mL and 1 pg/μL. This method was also tested in diseased kiwifruit tissues and can be seen as a rapid and dependable replacement to PCR methods for detecting only those infective kiwifruit materials with viable Psa.