Specific detection ofPythium aphanidermatum from hydroponic nutrient solution by booster PCR with DNA primers developed from mitochondrial DNA
ABSTRACT Pythium aphanidermatum causes damping-off and root rot of vegetable crops in hydroponic systems. A DNA probe was isolated and modified from a library
ofHindIII-digested mitochondrial DNA ofP. aphanidermatum that strongly hybridized to DNA ofP. aphanidermatum and weakly hybridized to DNA ofPythium deliense. Cross-hybridizing sequences were absent from DNA of plants and other related fungi. The probe detected as little as 5 ng
ofP. aphanidermatum DNA and 250 ng ofP. deliense DNA in slot-blot assays.P. aphanidermatum was detected by a hybridization assay of total DNA extracted directly from infected roots. A pair of oligonucleotide primers
P1 and RP2, which allowed amplification of a specific 0.65 kb DNA fragment ofP. aphanidermatum using polymerase chain reaction (PCR), was designed from a specific DNA probe. Specific amplification of this fragment fromP. aphanidermatum was highly sensitive, detecting template DNA as low as 0.1 pg total DNA by booster PCR. Specific booster PCR amplification
using P1 and RP2 was successful in detectingP. aphanidermatum in naturally infected nutrient solution and roots of vegetables in a field hydroponic system.