Special issue in Functional Plant Biology on "Flooding and low oxygen responses in plants"
The world is currently experiencing dramatic increases in flood events impacting on natural vegetation and crops. Flooding often results in low O2 status in root tissues during waterlogging, but sometimes also in shoot tissues when plants become completely submerged. Plants possess a suite of traits enabling tissue aeration and/or adjusted metabolism during hypoxia or even in the absence of O2. This special issue of Functional Plant Biology presents key papers for plant scientists on the quest to further address and improve flood tolerance of terrestrial plants. The papers address low O2 responses in roots, shoots or whole plants in controlled laboratory conditions or in the field situation using natural wetland plants as models as well as economically important crops, such as rice, wheat and barley. The studies advance our understanding of low O2 responses in plant tissues as caused by O2 shortage during flooding. However, in most instances, submergence not only leads to hypoxic or anoxic tissues, but inundation in water also results in accumulation of CO2 and the important plant hormone ethylene. Thus, carefully designed laboratory studies are often needed to unravel the mechanistic relationships between a combined decline in O2 followed by increases in CO2 and ethylene at tissue as well as on the cellular level.The study is published in:
Pedersen O, Perata P, Voesenek LACJ. (2017a) Flooding and low oxygen responses in plants. Functional Plant Biology 44: iii-vi.
Herzog M, Striker GG, Colmer TD, Pedersen O. (2016) Mechanisms of waterlogging tolerance in wheat – a review of root and shoot physiology. Plant, Cell & Environment 39: 1068-1086.
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.
The study is published in: