Detection of Peronophythora litchii on lychee by loop-mediated isothermal amplification assay

Downy blight caused by Peronophythora litchii is one of the most destructive diseases of lychee (Litchi chinensis Sonn.). Early diagnosis of the P. litchii pathogen should be the top priority for addressing disease epidemics and management. In this study, loop-mediated isothermal amplification (LAMP) assays targeting the M90 gene sequences were developed for specific detection of P. litchii. The detection limit of LAMP assay was 10 pg genomic DNA of P. litchii in 25 μL reaction mixtures. LAMP assay and nested polymerase chain reaction (PCR) assay showed higher sensitivity than conventional PCR. The LAMP assay could also detect the presence of P. litchii in infected leaves, fruits and soils. This study provides a simple, highly sensitive, rapid and reliable protocol for the early diagnosis of P. litchii on lychee.