title: Detection and validation of genomic regions associated with resistance to rust diseases in a worldwide hexaploid wheat landrace collection using BayesR and mixed linear model approaches.
abstract: BayesR and MLM association mapping approaches in common wheat landraces were used to identify genomic regions conferring resistance to Yr, Lr, and Sr diseases. Deployment of rust resistant cultivars is the most economically effective and environmentally friendly strategy to control rust diseases in wheat. However, the highly evolving nature of wheat rust pathogens demands continued identification, characterization, and transfer of new resistance alleles into new varieties to achieve durable rust control. In this study, we undertook genome-wide association studies (GWAS) using a mixed linear model (MLM) and the Bayesian multilocus method (BayesR) to identify QTL contributing to leaf rust (Lr), stem rust (Sr), and stripe rust (Yr) resistance. Our study included 676 pre-Green Revolution common wheat landrace accessions collected in the 1920-1930s by A.E. Watkins. We show that both methods produce similar results, although BayesR had reduced background signals, enabling clearer definition of QTL positions. For the three rust diseases, we found 5 (Lr), 14 (Yr), and 11 (Sr) SNPs significant in both methods above stringent false-discovery rate thresholds. Validation of marker-trait associations with known rust QTL from the literature and additional genotypic and phenotypic characterisation of biparental populations showed that the landraces harbour both previously mapped and potentially new genes for resistance to rust diseases. Our results demonstrate that pre-Green Revolution landraces provide a rich source of genes to increase genetic diversity for rust resistance to facilitate the development of wheat varieties with more durable rust resistance.
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.
authors.forename: Raj K
authors.initials: RK
authors.lastname: Pasam
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia.
authors.forename: Urmil
authors.initials: U
authors.lastname: Bansal
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.|School of Applied Systems Biology, La Trobe University, Bundoora, VIC, 3083, Australia.
authors.forename: Hans D
authors.initials: HD
authors.lastname: Daetwyler
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.
authors.forename: Kerrie L
authors.initials: KL
authors.lastname: Forrest
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.
authors.forename: Debbie
authors.initials: D
authors.lastname: Wong
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.
authors.forename: Joanna
authors.initials: J
authors.lastname: Petkowski
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia.|Dow AgroSciences Australia Ltd, Unit 12A, 84 Barnes Street, Tamworth, NSW, 2340, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Willey
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia.|International Maize and Wheat Improvement Center (CIMMYT), Carretera México-Veracruz Km. 45, El Batán, Texcoco, México, C.P. 56237, Mexico.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Randhawa
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia.
authors.forename: Mumta
authors.initials: M
authors.lastname: Chhetri
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia.
authors.forename: Hanif
authors.initials: H
authors.lastname: Miah
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia.
authors.forename: Josquin
authors.initials: J
authors.lastname: Tibbits
authors.affiliation: Faculty of Agriculture and Environment, Plant Breeding Institute-Cobbitty, The University of Sydney, PMB4011, Narellan, NSW, 2567, Australia. matthew.hayden@ecodev.vic.gov.au.
authors.forename: Harbans
authors.initials: H
authors.lastname: Bariana
authors.affiliation: Department of Economic Development, Jobs, Transport and Recourses, AgriBio Centre for AgriBioscience, Bundoora, VIC, 3083, Australia. harbans.bariana@sydney.edu.au.|School of Applied Systems Biology, La Trobe University, Bundoora, VIC, 3083, Australia. harbans.bariana@sydney.edu.au.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hayden
mesh_terms: D001487:Basidiomycota; D001499:Bayes Theorem; D002874:Chromosome Mapping; D060467:Disease Resistance / Q000235:genetics*; D056726:Genetic Association Studies; D014644:Genetic Variation; D005838:Genotype; D016014:Linear Models; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D020641:Polymorphism, Single Nucleotide; D011123:Polyploidy; D040641:Quantitative Trait Loci; D014908:Triticum / Q000235:genetics* / Q000382:microbiology