title: Inheritance of resistance to Ug99 stem rust in wheat cultivar Norin 40 and genetic mapping of Sr42.
abstract: Stem rust, caused by Puccinia graminis f. sp. tritici, is a devastating disease of wheat. The emergence of race TTKSK (Ug99) and new variants in Africa threatens wheat production worldwide. The best method of controlling stem rust is to deploy effective resistance genes in wheat cultivars. Few stem rust resistance (Sr) genes derived from the primary gene pool of wheat confer resistance to TTKSK. Norin 40, which carries Sr42, is resistant to TTKSK and variants TTKST and TTTSK. The goal of this study was to elucidate the inheritance of resistance to Ug99 in Norin 40 and map the Sr gene(s). A doubled haploid (DH) population of LMPG-6/Norin 40 was evaluated for resistance to the race TTKST. Segregation of 248 DH lines fitted a 1:1 ratio (χ (2) 1:1= 0.58, p = 0.45), indicating a single gene in Norin 40 conditioned resistance to Ug99. This was confirmed by an independent F(2:3) population also derived from the cross LMPG-6/Norin 40 where a 1:2:1 ratio (χ (2)1:2:1 = 0.69, p = 0.71) was observed following the inoculation with race TTKSK. Mapping with DNA markers located this gene to chromosome 6DS, the known location of Sr42. PCR marker FSD_RSA co-segregated with Sr42, and simple sequence repeat (SSR) marker BARC183 was closely linked (0.5 cM) to Sr42. A previous study found close linkage between FSD_RSA and SrCad, a temporarily designated gene that also confers resistance to Ug99, thus Sr42 may be the same gene or allelic. Marker FSD_RSA is suitable for marker-assisted selection (MAS) in wheat breeding programs to improve stem rust resistance, including Ug99.
authors.affiliation: Cereal Research Centre, Agriculture & Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB, R3T 2M9, Canada.
authors.forename: Habibollah
authors.initials: H
authors.lastname: Ghazvini
authors.forename: Colin W
authors.initials: CW
authors.lastname: Hiebert
authors.forename: Taye
authors.initials: T
authors.lastname: Zegeye
authors.forename: Sixin
authors.initials: S
authors.lastname: Liu
authors.forename: Mridull
authors.initials: M
authors.lastname: Dilawari
authors.forename: Toi
authors.initials: T
authors.lastname: Tsilo
authors.forename: James A
authors.initials: JA
authors.lastname: Anderson
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Rouse
authors.forename: Yue
authors.initials: Y
authors.lastname: Jin
authors.forename: Tom
authors.initials: T
authors.lastname: Fetch
mesh_terms: D000483:Alleles; D001487:Basidiomycota / Q000502:physiology; D002170:Canada; D002874:Chromosome Mapping / Q000379:methods*; D032461:Chromosomes, Plant / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D008040:Genetic Linkage; D056426:Genetic Loci / Q000235:genetics*; D005819:Genetic Markers; D006239:Haplotypes / Q000235:genetics; D040582:Inheritance Patterns / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D018547:Plant Stems / Q000235:genetics* / Q000382:microbiology; D014908:Triticum / Q000235:genetics* / Q000382:microbiology
chemical_list: D005819:Genetic Markers