A rapid, sensitive and field-deployable isothermal assay for the detection of Verticillium alfalfae

AbstractThe genus Verticillium contains 10 plant pathogenic species that are responsible for billions of dollars of crop losses annually on more than 400 plant species worldwide. On alfalfa, Verticillium alfalfae causes Verticillium wilt, a disease with the potential to reduce yields of susceptible cultivars by the second harvest year and to limit the productive stand life to less than 3 years. Susceptible alfalfa cultivars exhibit disease symptoms that include chlorotic V-shaped lesions at the leaf tip that cause entire leaflets to become bleached and twisted, leading to defoliation. Stems often remain green after all leaflets have desiccated, and discolouration, stunting and wilting of shoots is visible. Internally, the taproot can show yellow to brown vascular discolouration. International quarantines sometimes prohibit the entry of alfalfa samples contaminated with the Verticillium pathogen. In this investigation, we developed a recombinase polymerase amplification (RPA) assay coupled with a lateral f...