Bremia polycephala and Bremia sawadae spp. nov (Peronosporaceae; Oomycota), parasitic to Northeast Asian Asteraceae

Abstract

All confirmed members of the genus Bremia (Peronosporales; Oomycetes) parasitise diverse plants of the family Asteraceae. For more than one hundred years, Bremia was considered a monotypic genus. with a well-known species, B. lactucae. However, studies since the turn of the century have revealed that Bremia contains many specialised species. During an investigation of the diversity of Bremia species, we found two so far undescribed species of Bremia in Korea, each of which is parasitic to Crepidiastrum denticulatum and Ixeris polycephala, both native to Northeast Asia. Through multigene phylogenies (based on ITS, LSU D1-3 rDNA, coxl, cox2, cox2-1 spacer mtDNA, and BrRxLR11) and the morphological characteristics, we introduce them as new species, Bremia polycephala (ex Ixeris polycephala) and Bremia sawadae (ex Crepidiastrum denticulatwn).