Phytophthora mississippiae sp. nov., a New Species Recovered from Irrigation Reservoirs at a Plant Nursery in Mississippi

A previously unknown Phytophthora species was recovered from irrigation water in Mississippi. This novel species produced both nonpapillate and semipapillate sporangia, and catenulate hyphal swellings. All examined isolates were compatibility type A1. Ornamented oogonia with amphigynous antheridia and plerotic oospores were produced when this novel species was paired with A2 mating type testers of P. cryptogea and P. nicotianae in polycarbonate membrane tests. Sequence analyses of the rDNA internal transcribed spacer (ITS) region and the mitochondrially encoded cytochrome c oxidase 1 (cox 1) gene placed this species in clade 6 of the genus Phytophthora. Based on the morphological, physiological and molecular features, this new species is named as Phytophthora mississippiae sp. nov. The implications of these results are discussed