Development of a Real-Time Loop-Mediated Isothermal Amplification Assay for Stromatinia cepivora in Response to an Outbreak in Northern Idaho

Stromatinia cepivora is the causal agent of white rot disease of Allium species. In 2018, white rot was observed in Boundary County in Northern Idaho in garlic and onion plants in a variety of home and market garden operations. Because the university diagnostic laboratory for Idaho is situated in Parma within a regulated area for S. cepivora, a point-of-care (POC) assay using real-time loop-mediated isothermal amplification (LAMP) was developed to minimize the amount of material potentially sent to the diagnostic laboratory. The LAMP assay was used with a BioRanger platform, and although the limit of detection meant it was 100 times less sensitive than TaqMan, it was capable of detecting a single sclerotium. This study demonstrates the rapid development and deployment of a POC-suitable LAMP assay. Despite limitations in sensitivity and dynamic range compared with real-time PCR, POC LAMP assays are advantageous where biosecurity concerns prohibit the movement of material suitable for diagnosis as well as facilitating engagement with growers.