title: Identification of Putative Candidate Genes for Water Stress Tolerance in Canola (Brassica napus).
abstract: Drought stress can directly inhibit seedling establishment in canola (Brassica napus), resulting in lower plant densities and reduced yields. To dissect this complex trait, 140 B. napus accessions were phenotyped under normal (0.0 MPa, S0) and water-stressed conditions simulated by polyethylene glycol (PEG) 6000 (-0.5 MPa, S5) in a hydroponic system. Phenotypic variation and heritability indicated that the root to shoot length ratio was a reliable indicator for water stress tolerance. Thereafter, 66 accessions (16 water stress tolerant, 34 moderate and 16 sensitive lines) were genotyped using 25,495 Brassica single nucleotide polymorphisms (SNPs). Genome-wide association studies (GWAS) identified 16 loci significantly associated with water stress response. Two B. napus accessions were used for RNA sequencing, with differentially-expressed genes under normal and water-stressed conditions examined. By combining differentially-expressed genes detected by RNA sequencing with significantly associated loci from GWAS, 79 candidate genes were identified, of which eight were putatively associated with drought tolerance based on gene ontology of Arabidopsis. Functional validation of these genes may confirm key drought-related genes for selection and breeding in B. napus. Our results provide insight into the genetic basis of water stress tolerance in canola.
authors.affiliation: Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China ; Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western Australia Perth, WA, Australia.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Plant Breeding Department, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University Giessen, Germany ; School of Agriculture and Food Sciences and Centre for Integrative Legume Research, The University of Queensland Brisbane, QLD, Australia.
authors.forename: Annaliese S
authors.initials: AS
authors.lastname: Mason
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Liu
authors.affiliation: Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western Australia Perth, WA, Australia.
authors.forename: Xuechen
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Luo
authors.affiliation: Australian Grains Genebank, Department of Economic Development Jobs Transport and Resources Horsham, VIC, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Redden
authors.affiliation: Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western Australia Perth, WA, Australia ; School of Agriculture and Food Sciences and Centre for Integrative Legume Research, The University of Queensland Brisbane, QLD, Australia.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Batley
authors.affiliation: Ministry of Agriculture (MOA) Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Liyong
authors.initials: L
authors.lastname: Hu
authors.affiliation: Centre for Plant Genetics and Breeding, School of Plant Biology, Faculty of Science and The UWA Institute of Agriculture, The University of Western Australia Perth, WA, Australia.
authors.forename: Guijun
authors.initials: G
authors.lastname: Yan
keywords: RNA sequencing; canola; drought-related genes; genome-wide association study; water stress tolerance