Development of lateral flow assay combined with recombinase polymerase amplification for highly sensitive detection of Dickeya solani.

Dickeya solani, one of the most significant bacterial pathogens, infects potato plants, resulting in severe economic damage. In this study, a lateral flow assay (LFA) combined with isothermal DNA amplification was developed for rapid, specific, and sensitive diagnosis of the potato blackleg disease caused by D. solani. Recombinase polymerase amplification (RPA) was chosen for this purpose. Five primer pairs specific to different regions of the D. solani genome were designed and screened. A primer pair providing correct recognition of the target sequence was aligned with the SOL-C region specific to D. solani and flanked by fluorescein (forward primer) and biotin (reverse primer). Lateral flow test strips were constructed to detect DNA amplicons. The RPA-LFA demonstrated a detection limit equal to 14,000 D. solani colony-forming units per gram of potato tuber. This assay provided sensitivity corresponding to the polymerase chain reaction (PCR) but was implemented at a fixed temperature (39 °C) over 30 min. No unspecific reactions with Pectobacterium, Clavibacter, and other Dickeya species were observed. Detection of latent infection of D. solani in the potato tubers by the developed RPA-LFA was verified by PCR. The obtained results confirmed that RPA-LFA has great potential for highly sensitive detection of latent infection.