Molecular systematics of the cotton root rot pathogen, Phymatotrichopsis omnivora.
Cotton root rot is an important soilborne disease of cotton and numerous dicot plants in the south-western United States and Mexico. The causal organism, Phymatotrichopsis omnivora (= Phymatotrichum omnivorum), is known only as an asexual, holoanamorphic (mitosporic) fungus, and produces conidia resembling those of Botrytis. Although the corticoid basidiomycetes Phanerochaete omnivora (Polyporales) and Sistotrema brinkmannii (Cantharellales; both Agaricomycetes) have been suggested as teleomorphs of Phymatotrichopsis omnivora, phylogenetic analyses of nuclear small- and large-subunit ribosomal DNA and subunit 2 of RNA polymerase II from multiple isolates indicate that it is neither a basidiomycete nor closely related to other species of Botrytis (Sclerotiniaceae, Leotiomycetes). Phymatotrichopsis omnivora is a member of the family Rhizinaceae, Pezizales (Ascomycota: Pezizomycetes) allied to Psilopezia and Rhizina.
Marek
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Department of Entomology and Plant Pathology, 127 Noble Research Center, Oklahoma State University, Stillwater, OK 74078-3033, USA.
Hansen
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Romanish
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Thorn
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