title: Mapping and pyramiding of qualitative and quantitative resistance to stripe rust in barley.
abstract: The identification and location of sources of genetic resistance to plant diseases are important contributions to the development of resistant varieties. The combination of different sources and types of resistance in the same genotype should assist in the development of durably resistant varieties. Using a doubled haploid (DH), mapping population of barley, we mapped a qualitative resistance gene ( Rpsx) to barley stripe rust in the accession CI10587 (PI 243183) to the long arm of chromosome 1(7H). We combined the Rpsx gene, through a series of crosses, with three mapped and validated barley stripe rust resistance QTL alleles located on chromosomes 4(4H) (QTL4), 5(1H) (QTL5), and 7(5H) (QTL7). Three different barley DH populations were developed from these crosses, two combining Rpsx with QTL4 and QTL7, and the third combining Rpsx with QTL5. Disease severity testing in four environments and QTL mapping analyses confirmed the effects and locations of Rpsx, QTL4, and QTL5, thereby validating the original estimates of QTL location and effect. QTL alleles on chromosomes 4(4H) and 5(1H) were effective in decreasing disease severity in the absence of the resistance allele at Rpsx. Quantitative resistance effects were mainly additive, although magnitude interactions were detected. Our results indicate that combining qualitative and quantitative resistance in the same genotype is feasible. However, the durability of such resistance pyramids will require challenge from virulent isolates, which currently are not reported in North America.
authors.affiliation: Departamento de Producción Vegetal, Est. Exp. "Dr. Mario A. Cassinoni", Facultad de Agronomía, Universidad de la República, Ruta 3 Km.373, Paysandú 60000, Uruguay.
authors.forename: A J
authors.initials: AJ
authors.lastname: Castro
authors.forename: F
authors.initials: F
authors.lastname: Capettini
authors.forename: A E
authors.initials: AE
authors.lastname: Corey
authors.forename: T
authors.initials: T
authors.lastname: Filichkina
authors.forename: P M
authors.initials: PM
authors.lastname: Hayes
authors.forename: A
authors.initials: A
authors.lastname: Kleinhofs
authors.forename: D
authors.initials: D
authors.lastname: Kudrna
authors.forename: K
authors.initials: K
authors.lastname: Richardson
authors.forename: S
authors.initials: S
authors.lastname: Sandoval-Islas
authors.forename: C
authors.initials: C
authors.lastname: Rossi
authors.forename: H
authors.initials: H
authors.lastname: Vivar
mesh_terms: D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics; D003433:Crosses, Genetic; D005838:Genotype; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology; D007113:Immunity, Innate / Q000235:genetics*; D008957:Models, Genetic; D010641:Phenotype; D010935:Plant Diseases; D018515:Plant Leaves / Q000235:genetics*; D040641:Quantitative Trait Loci; D013045:Species Specificity