Ypt1 gene-based detection of Phytophthora sojae in a loop-mediated isothermal amplification assay

This study reports the development of a loop-mediated isothermal amplification procedure (LAMP) for the detection of Phytophthora sojae, the causal agent of soybean Phytophthora root rot disease. The Ras-related protein-coding gene (Ypt1) was used to design a set of six primers for LAMP detection of P. sojae in infected soybean tissue and in soil from infested fields. The advantage of the LAMP method is that neither thermocyclers nor gel electrophoresis are needed for testing. Positive LAMP results are visualised directly as a colour change in a test tube. The PsYpt1 -LAMP assay amplified the target in 60 min at 65 degrees C with a high specificity and sensitivity. Hydroxynaphthol blue was evaluated as an end-point detection method for LAMP. A portable NaOH lysis method suitable for DNA extraction from infected plant tissue was effective in conjunction with LAMP. Thus, the PsYpt1-LAMP assay shows potential as a reliable, rapid and cost-effective method for the visual detection of P. sojae pathogen in field-grown soybean plants and production fields.