title: Multi-environment multi-QTL association mapping identifies disease resistance QTL in barley germplasm from Latin America.
abstract: Multi-environment multi-QTL mixed models were used in a GWAS context to identify QTL for disease resistance. The use of mega-environments aided the interpretation of environment-specific and general QTL. Diseases represent a major constraint for barley (Hordeum vulgare L.) production in Latin America. Spot blotch (caused by Cochliobolus sativus), stripe rust (caused by Puccinia striiformis f.sp. hordei) and leaf rust (caused by Puccinia hordei) are three of the most important diseases that affect the crop in the region. Since fungicide application is not an economically or environmentally sound solution, the development of durably resistant varieties is a priority for breeding programs. Therefore, new resistance sources are needed. The objective of this work was to detect genomic regions associated with field level plant resistance to spot blotch, stripe rust, and leaf rust in Latin American germplasm. Disease severities measured in multi-environment trials across the Americas and 1,096 SNPs in a population of 360 genotypes were used to identify genomic regions associated with disease resistance. Optimized experimental design and spatial modeling were used in each trial to estimate genotypic means. Genome-Wide Association Mapping (GWAS) in each environment was used to detect Quantitative Trait Loci (QTL). All significant environment-specific QTL were subsequently included in a multi-environment-multi-QTL (MEMQ) model. Geographical origin and inflorescence type were the main determinants of population structure. Spot blotch severity was low to intermediate while leaf and stripe rust severity was high in all environments. Mega-environments were defined by locations for spot blotch and leaf rust. Significant marker-trait associations for spot blotch (9 QTL), leaf (6 QTL) and stripe rust (7 QTL) and both global and environment-specific QTL were detected that will be useful for future breeding efforts.
authors.affiliation: Departmento de Biometria, Estadistica y Computo, Facultad de Agronomía, Universidad de la República, Garzón 780, Montevideo, Uruguay, luciag@fagro.edu.uy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Gutiérrez
authors.forename: Silvia
authors.initials: S
authors.lastname: Germán
authors.forename: Silvia
authors.initials: S
authors.lastname: Pereyra
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Hayes
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Pérez
authors.forename: Flavio
authors.initials: F
authors.lastname: Capettini
authors.forename: Andres
authors.initials: A
authors.lastname: Locatelli
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Berberian
authors.forename: Esteban E
authors.initials: EE
authors.lastname: Falconi
authors.forename: Rigoberto
authors.initials: R
authors.lastname: Estrada
authors.forename: Dario
authors.initials: D
authors.lastname: Fros
authors.forename: Victor
authors.initials: V
authors.lastname: Gonza
authors.forename: Hernan
authors.initials: H
authors.lastname: Altamirano
authors.forename: Julio
authors.initials: J
authors.lastname: Huerta-Espino
authors.forename: Edgar
authors.initials: E
authors.lastname: Neyra
authors.forename: Gisella
authors.initials: G
authors.lastname: Orjeda
authors.forename: Sergio
authors.initials: S
authors.lastname: Sandoval-Islas
authors.forename: Ravi
authors.initials: R
authors.lastname: Singh
authors.forename: Kelly
authors.initials: K
authors.lastname: Turkington
authors.forename: Ariel J
authors.initials: AJ
authors.lastname: Castro
mesh_terms: D001203:Ascomycota; D001487:Basidiomycota; D001947:Breeding; D032461:Chromosomes, Plant; D060467:Disease Resistance / Q000235:genetics*; D056726:Genetic Association Studies; D005838:Genotype; D001467:Hordeum / Q000235:genetics* / Q000382:microbiology; D008953:Models, Anatomic; D015233:Models, Statistical; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics; D040641:Quantitative Trait Loci