Development of an Innovative Loop-Mediated Isothermal Amplification (LAMP) Assay for the Rapid On-Site Detection of Phytophthora infestans

Abstract Late blight of potato, caused by Phytophthora infestans , is a major constraint to potato production. Early detection, coupled with a knowledge of the genotype, can ensure the timely implementation of optimal disease management strategies. In this study, we developed a new loop-mediated isothermal amplification (LAMP) assay designed to amplify the ypt1 gene for P. infestans which can readily distinguish P. infestans from other potato oomycetes pathogens such as P. erythroseptica, and Pythium ultimum within 10 min on a Genie II or III platform. Six other published LAMP assays were compared with our assay on a Genie II using the same concentration of primers used in the original published assays. On the Genie platform, our assay was more reliable than other assays based on specificity and sensitivity. Our assay did not detect P. mirabilis or P. phaseoli . The lower limit of detection of our assay was determined to be 0.001 ng using DNA from pure cultures and 0.05 ng using DNA from infected leaves. LAMP and quick DNA extraction technology, coupled with a portable platform such as the Genie II or III, enable the rapid on-site detection of P. infestans .