Histological and Molecular Detections of Peronospora variabilis Gäum Oospores in Seeds of Quinoa (Chenopodium quinoa L.)

The oospores of Perosnospora variabilis Gaum, the causal agent of downy mildew of quinoa (Chenopodium quinoa L.), were detected histologically in the perianth of quinoa seed, the pericarp, testa, perisperm, and the cotyledons of the embryo. The histological detections of oospores were confirmed by the polymerase chain reaction (PCR) using the DNA extracted from the perianth and all of the seed parts. The percentage occurrence of oospores in examined seed samples was high in the perianth (90%) followed by the seed coat (87%) whereas, the lowest percentages were found in the embryo (3%) and the perisperm (2%).