title: Novel Phakopsora pachyrhizi extracellular proteins are ideal targets for immunological diagnostic assays.
abstract: Phakopsora pachyrhizi, the causal agent of Asian soybean rust (ASR), continues to spread across the southeast and midsouth regions of the United States, necessitating the use of fungicides by producers. Our objective in this research was to identify ASR proteins expressed early during infection for the development of immunodiagnostic assays. We have identified and partially characterized a small gene family encoding extracellular proteins in the P. pachyrhizi urediniospore wall, termed PHEPs (for Phakopsora extracellular protein). Two highly expressed protein family members, PHEP 107 and PHEP 369, were selected as ideal immunodiagnostic targets for antibody development, after we detected PHEPs in plants as early as 3 days postinfection (dpi). Monoclonal antibodies (MAbs; 2E8E5-1 and 3G6H7-3) generated against recombinant PHEP 369 were tested for sensitivity against the recombinant protein and extracts from ASR-infected plants and for specificity against a set of common soybean pathogens. These antibodies should prove applicable in immunodiagnostic assays to detect infected soybeans and to identify ASR spores from sentinel surveillance plots.
authors.affiliation: USDA, Agricultural Research Service, Foreign Disease-Weed Science Research Unit, Ft. Detrick, MD, USA.
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Luster
authors.forename: Michael B
authors.initials: MB
authors.lastname: McMahon
authors.forename: H Herb
authors.initials: HH
authors.lastname: Edwards
authors.forename: Britney L
authors.initials: BL
authors.lastname: Boerma
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Lewis Ivey
authors.forename: Sally A
authors.initials: SA
authors.lastname: Miller
authors.forename: Anne E
authors.initials: AE
authors.lastname: Dorrance
mesh_terms: D000595:Amino Acid Sequence; D000908:Antibodies, Fungal / Q000096:biosynthesis / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology; D000918:Antibody Specificity; D001487:Basidiomycota / Q000276:immunology* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016415:Sequence Alignment; D013025:Glycine max / Q000382:microbiology*
chemical_list: D000908:Antibodies, Fungal; D000911:Antibodies, Monoclonal; D005656:Fungal Proteins; D011994:Recombinant Proteins