title: Two novel species representing a new clade and cluster of Phytophthora.
abstract: Phytophthora stricta sp. nov. and Phytophthora macilentosa sp. nov. are described based on morphological, physiological and molecular characters in this study. Phytophthora stricta represents a previously unknown clade in the rRNA internal transcribed spacer (ITS)-based phylogeny. Phytophthora macilentosa, along with nine other species, consistently forms a high temperature-tolerant cluster within ITS clade 9. These observations are supported by the sequence analysis of the mitochondrial cytochrome c oxidase 1 gene. Both species are heterothallic and all examined isolates are A1 mating type. Phytophthora stricta produces nonpapillate and slightly caducous sporangia. This species is named after its characteristic constrictions on sporangiophores. Phytophthora macilentosa produces nonpapillate and noncaducous sporangia, which are mostly elongated obpyriform with a high length to breadth ratio. Both species were recovered from irrigation water of an ornamental plant nursery in Mississippi, USA and P. stricta was also recovered from stream water in Virginia, USA.
authors.affiliation: Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA. Electronic address: yxiao9@vt.edu.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.affiliation: Agricultural Research Service, United States Department of Agriculture, Thad Cochran Southern Horticultural Laboratory, Poplarville, MS, USA.
authors.forename: Warren E
authors.initials: WE
authors.lastname: Copes
authors.affiliation: Hampton Roads Agricultural Research and Extension Center, Virginia Polytechnic Institute and State University, Virginia Beach, VA, USA.
authors.forename: Chuanxue
authors.initials: C
authors.lastname: Hong
mesh_terms: D016000:Cluster Analysis; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D008853:Microscopy; D008922:Mississippi; D008969:Molecular Sequence Data; D010802:Phylogeny; D010838:Phytophthora / Q000145:classification* / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D017422:Sequence Analysis, DNA; D013172:Spores, Fungal / Q000166:cytology; D014768:Virginia; D014871:Water Microbiology
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer; D003576:Electron Transport Complex IV
keywords: High temperature-tolerant cluster; ITS; Irrigation water; Phytophthora macilentosa; Phytophthora stricta; cox1