title: Molecular genetic characterization of the Lr34/Yr18 slow rusting resistance gene region in wheat.
abstract: Wheat expressed sequence tags (wESTs) were identified in a genomic interval predicted to span the Lr34/Yr18 slow rusting region on chromosome 7DS and that corresponded to genes located in the syntenic region of rice chromosome 6 (between 2.02 and 2.38 Mb). A subset of the wESTs was also used to identify corresponding bacterial artificial chromosome (BAC) clones from the diploid D genome of wheat (Aegilops tauschii). Conservation and deviation of micro-colinearity within blocks of genes were found in the D genome BACs relative to the orthologous sequences in rice. Extensive RFLP analysis using the wEST derived clones as probes on a panel of wheat genetic stocks with or without Lr34/Yr18 revealed monomorphic patterns as the norm in this region of the wheat genome. A similar pattern was observed with single nucleotide polymorphism analysis on a subset of the wEST derived clones and subclones from corresponding D genome BACs. One exception was a wEST derived clone that produced a consistent RFLP pattern that distinguished the Lr34/Yr18 genetic stocks and well-established cultivars known either to possess or lack Lr34/Yr18. Conversion of the RFLP to a codominant sequence tagged site (csLV34) revealed a bi-allelic locus, where a variant size of 79 bp insertion in an intron sequence was associated with lines or cultivars that lacked Lr34/Yr18. This association with Lr34/Yr18 was validated in wheat cultivars from diverse backgrounds. Genetic linkage between csLV34 and Lr34/Yr18 was estimated at 0.4 cM.
authors.affiliation: CSIRO Plant Industry, GPO Box 1600, Canberra, ACT, 2601, Australia. evans.lagudah@csiro.au
authors.forename: E S
authors.initials: ES
authors.lastname: Lagudah
authors.forename: H
authors.initials: H
authors.lastname: McFadden
authors.forename: R P
authors.initials: RP
authors.lastname: Singh
authors.forename: J
authors.initials: J
authors.lastname: Huerta-Espino
authors.forename: H S
authors.initials: HS
authors.lastname: Bariana
authors.forename: W
authors.initials: W
authors.lastname: Spielmeyer
mesh_terms: D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial; D032461:Chromosomes, Plant; D020224:Expressed Sequence Tags; D017343:Genes, Plant; D005819:Genetic Markers; D018745:Genome, Plant; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D014908:Triticum / Q000235:genetics* / Q000502:physiology
chemical_list: D005819:Genetic Markers