Open AccessReal-Time PCR Detection of the Onion Downy Mildew Pathogen Peronospora destructor From Symptomless Onion Seedlings and Soils
Author(s) -
Kazuki Fujiwara,
Hiroyoshi Inoue,
R. M. Sonoda,
Yutaka Iwamoto,
Motoaki Kusaba,
Nobutada Tashiro,
Atsushi Miyasaka
Publication year - 2021
Publication title -
plant disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.663
H-Index - 108
eISSN - 1943-7692
pISSN - 0191-2917
DOI - 10.1094/pdis-05-20-1095-re
Subject(s) - downy mildew , biology , oospore , pathogen , fungicide , conidium , horticulture , outbreak , botany , agronomy , veterinary medicine , microbiology and biotechnology , virology , medicine
An outbreak of downy mildew disease of onion, caused by Peronospora destructor, in Japan in 2016 necessitated a reevaluation of the primary inoculum sources to optimize disease management. Detection of the P. destructor pathogen in plants with asymptomatic infection and in soil would guide the application of fungicides according to the extent of infection before disease development. Here, we detected P. destructor in both plants and soil using newly developed primer sets (Pd ITS and Pd ITS 614) by both conventional and real-time PCR. Validation by real-time PCR with Pd ITS 614 showed that P. destructor DNA was amplified from symptomless seedlings at 3.7 × 10 2 to 1.0 × 10 0 conidium cells/50 mg leaf tissue, suggesting the detection of asymptomatic infection. Real-time PCR with Pd ITS amplified pathogen DNA from field soils at 1.6 × 10 3 to 8.3 × 10 1 oospore cells/g of soil. This real-time PCR assay provides a useful tool for identifying and quantifying inoculum sources, which may be the foundation of the design of integrated disease management strategies.