Detection of f. sp. by Using Loop-Mediated Isothermal Amplification.

We developed a loop-mediated isothermal amplification (LAMP) assay for detecting f. sp. , the causal agent of wilt in strawberry plants. This assay was based on genomic regions between the portions of transposable elements and of the fungus. The LAMP assay allowed the efficient detection of f. sp. DNA by visual inspection, without requiring gel electrophoresis. The detection limit was 100 pg of genomic DNA, which is comparable to that of PCR. The LAMP primers successfully discriminated f. sp. strains from nonpathogenic strains and other fungi. The LAMP assay at 63°C, which was found to be the optimal treatment temperature, for 1.5 h successfully detected f. sp. California strains GL1270 and GL1385. When the assay was performed using a Genelyzer FIII portable fluorometer, these California strains were successfully detected in 1 h. The assay facilitated the detection of conidia in soil samples after they were precultured on a selective medium for (FoG2) as well as latent infection in strawberry plants after preculturing. The LAMP assay for visual inspection of DNA required only a heating block and an incubator, reducing the cost of this assay. Thus, it could be suitable for the detection of f. sp. strains in centers that store prefoundation and foundation stocks of strawberry, including plant nurseries.