Genome-informed diagnostics for specific and rapid detection of Pectobacterium species using recombinase polymerase amplification coupled with a lateral flow device

Pectobacterium species cause serious bacterial soft rot diseases worldwide on economically important fruit and vegetable crops including tomato and potato. Accurate and simple methods are essential for rapid pathogen identification and timely management of the diseases. Recombinase polymerase amplification (RPA) combined with a lateral flow device (LFD) was developed for specific detection of Pectobacterium sp. directly from infected plant materials with no need for DNA isolation. The specificity of RPA-LFD was tested with 26 Pectobacterium sp. strains and 12 non-Pectobacterium species and no false positive or false negative outcomes were observed. RPA primers and probe for host control were also developed to detect the host genome for enhanced reliability and accuracy of the developed assay. The detection limit of 10 fg was obtained with both sensitivity and spiked sensitivity assays. No inhibitory effects were observed on the RPA assay when targets (pathogen and host) were directly detected from infected potato and tomato sap. The developed RPA assay has numerous applications from routine diagnostics at point-of-care, biosecurity, surveillance and disease management to epidemiological studies. In addition, this tool can also be used to discover reservoir hosts for Pectobacterium species.