title: Mechanisms of waterlogging tolerance in wheat--a review of root and shoot physiology.
abstract: We review the detrimental effects of waterlogging on physiology, growth and yield of wheat. We highlight traits contributing to waterlogging tolerance and genetic diversity in wheat. Death of seminal roots and restriction of adventitious root length due to O2 deficiency result in low root:shoot ratio. Genotypes differ in seminal root anoxia tolerance, but mechanisms remain to be established; ethanol production rates do not explain anoxia tolerance. Root tip survival is short-term, and thereafter, seminal root re-growth upon re-aeration is limited. Genotypes differ in adventitious root numbers and in aerenchyma formation within these roots, resulting in varying waterlogging tolerances. Root extension is restricted by capacity for internal O2 movement to the apex. Sub-optimal O2 restricts root N uptake and translocation to the shoots, with N deficiency causing reduced shoot growth and grain yield. Although photosynthesis declines, sugars typically accumulate in shoots of waterlogged plants. Mn or Fe toxicity might occur in shoots of wheat on strongly acidic soils, but probably not more widely. Future breeding for waterlogging tolerance should focus on root internal aeration and better N-use efficiency; exploiting the genetic diversity in wheat for these and other traits should enable improvement of waterlogging tolerance.
authors.affiliation: Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 3rd floor, 2100, Copenhagen, Denmark.|School of Plant Biology, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Western Australia, Australia.
authors.forename: Max
authors.initials: M
authors.lastname: Herzog
authors.affiliation: IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Avenida San Martín 4453, CPA 1417, DSE Buenos Aires, Argentina.|School of Plant Biology, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Western Australia, Australia.
authors.forename: Gustavo G
authors.initials: GG
authors.lastname: Striker
authors.affiliation: School of Plant Biology, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Western Australia, Australia.
authors.forename: Timothy D
authors.initials: TD
authors.lastname: Colmer
authors.affiliation: Freshwater Biological Laboratory, Department of Biology, University of Copenhagen, Universitetsparken 4, 3rd floor, 2100, Copenhagen, Denmark.|School of Plant Biology, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Western Australia, Australia.|Institute of Advanced Studies, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Western Australia, Australia.
authors.forename: Ole
authors.initials: O
authors.lastname: Pedersen
mesh_terms: D000222:Adaptation, Physiological; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology*; D018520:Plant Shoots / Q000502:physiology*; D012639:Seeds / Q000502:physiology; D014908:Triticum / Q000502:physiology*; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: O2 deficiency; adventitious roots; aerenchyma; flooding tolerance; genotypic variation; micronutrient toxicity; nitrogen deficiency; recovery ability; root anoxia tolerance; wheat (Triticum aestivum)