Rediscovery of Seven Long-Forgotten Species of Peronospora and Plasmopara (Oomycota)

Abstract

The family Peronosporaceae, an obligate biotrophic group of Oomycota, causes downy mildew disease on many cultivated and ornamental plants such as beet, cucumber, grape, onion, rose, spinach, and sunflower. To investigate the diversity of Peronosporaceae species in Korea, we performed morphological analysis for dried plant herbariums with downy mildew infections by two largest genera,PeronosporaandPlasmopara. As a result, it was confirmed that there are five species ofPeronosporaand two species ofPlasmopara, which have been so far unrecorded in Korea, as well as rarely known in the world;Pl. angustiterminalis(exXanthium strumarium),Pl. siegesbeckiae(exSiegesbeckia glabrescens),P. chenopodii-ambrosioidis(exChenopodium ambrosioides),P. chenopodii-ficifolii(exChenopodium ficifolium),P. clinopodii(exClinopodiumcf.vulgare),P. elsholtziae(exElsholtzia ciliata), andP. lathyrina(exLathyrus japonicus). In addition, their phylogenetic relationship was inferred by molecular sequence analysis of ITS, LSU rDNA, andcox2mtDNA. By rediscovering the seven missing species and barcoding their DNA sequences, this study provides valuable insights into the diversity and evolutionary studies of downy mildew pathogens.