title: The use of conventional and quantitative real-time PCR assays for Polymyxa graminis to examine host plant resistance, inoculum levels and intraspecific variation.
abstract: * A real-time PCR protocol based on 18S rDNA sequences was developed to provide a specific, sensitive and quantitative assay for the root-infecting virus vector Polymyxa graminis. * The assay was calibrated with zoospore suspensions and inoculated roots and then shown to work with naturally infected plant roots and infested soil. Both the temperate P. graminis ribotypes previously described are detected but are not distinguished. DNA from related plasmodiophorids and from a range of fungi and plants was not detected. * Different genotypes of Triticum were grown in a soil infested with P. graminis and Soil-borne cereal mosaic virus (SBCMV). The genotypes differed in susceptibility to P. graminis, the least susceptible being the Triticum monococcum accession K-58505. * Conventional PCR assays and sequencing of amplified rDNA fragments showed that P. graminis isolates infecting wheat were mostly, but not exclusively, of ribotype II. Ribotype II was clearly associated with SBCMV transmission and seems to occur preferentially on wheat whereas ribotype I is mostly associated with barley.
authors.affiliation: Wheat Pathogenesis Programme, Plant Pathogen Interactions Division, Rothamsted Research, Harpenden, Herts, AL5 2JQ, UK. elaine.ward@bbsrc.ac.uk
authors.forename: Elaine
authors.initials: E
authors.lastname: Ward
authors.forename: Kostya
authors.initials: K
authors.lastname: Kanyuka
authors.forename: Juliet
authors.initials: J
authors.lastname: Motteram
authors.forename: Dmitry
authors.initials: D
authors.lastname: Kornyukhin
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Adams
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal; D005658:Fungi / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D009029:Mosaic Viruses; D010935:Plant Diseases / Q000382:microbiology* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000379:methods*; D021521:Ribotyping; D012689:Sequence Homology, Nucleic Acid; D012988:Soil Microbiology; D014908:Triticum / Q000235:genetics / Q000382:microbiology / Q000821:virology
chemical_list: D004271:DNA, Fungal