title: Fine mapping and identification of a candidate gene for the barley Un8 true loose smut resistance gene.
abstract: The candidate gene for the barley Un8 true loose smut resistance gene encodes a deduced protein containing two tandem protein kinase domains. In North America, durable resistance against all known isolates of barley true loose smut, caused by the basidiomycete pathogen Ustilago nuda (Jens.) Rostr. (U. nuda), is under the control of the Un8 resistance gene. Previous genetic studies mapped Un8 to the long arm of chromosome 5 (1HL). Here, a population of 4625 lines segregating for Un8 was used to delimit the Un8 gene to a 0.108 cM interval on chromosome arm 1HL, and assign it to fingerprinted contig 546 of the barley physical map. The minimal tilling path was identified for the Un8 locus using two flanking markers and consisted of two overlapping bacterial artificial chromosomes. One gene located close to a marker co-segregating with Un8 showed high sequence identity to a disease resistance gene containing two kinase domains. Sequence of the candidate gene from the parents of the segregating population, and in an additional 19 barley lines representing a broader spectrum of diversity, showed there was no intron in alleles present in either resistant or susceptible lines, and fifteen amino acid variations unique to the deduced protein sequence in resistant lines differentiated it from the deduced protein sequences in susceptible lines. Some of these variations were present within putative functional domains which may cause a loss of function in the deduced protein sequences within susceptible lines.
authors: Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada.
authors: Wen
authors: W
authors: Zang
authors: Peter E
authors: PE
authors: Eckstein
authors: Mark
authors: M
authors: Colin
authors: Doug
authors: D
authors: Voth
authors: Axel
authors: A
authors: Himmelbach
authors: Sebastian
authors: S
authors: Beier
authors: Nils
authors: N
authors: Stein
authors: Graham J
authors: GJ
authors: Scoles
authors: Aaron D
authors: AD
authors: Beattie
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001487:Basidiomycota / Q000472:pathogenicity; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant; D008040:Genetic Linkage; D005819:Genetic Markers; D005838:Genotype; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology; D007438:Introns; D008969:Molecular Sequence Data; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D054730:Protein Interaction Domains and Motifs; D026801:Synteny
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers; D010940:Plant Proteins