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How do plants deal with flooding?

Plants can't move and get out of the way when water levels become difficult to handle. Flooding and soil saturation leads to a depletion of oxygen in the soil and reduction of light and carbon dioxide availability. So how do plants deal with the stress of being flooded?

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How do plants deal with flooding?

  1. 1. Plant responses to flooding and waterlogging
  2. 2. Overview  Issues with too much water  Plant strategies  Root adaptations  Shoot adaptations  Signalling and hormones  Summary
  3. 3. Flooding of plants Difference – Flooding – complete inundation of the soil and above ground area – Waterlogging – saturation of the soil with water One of the most common and widespread stressors that plants must deal with Important for planning and management of crops and agricultural pastures
  4. 4. Impacts of waterlogging and flooding Hypoxia and anoxia of soils Loss of nitrogen fixing bacteria Toxic anaerobic Submerged plants have reduced availability of: – Light – CO₂
  5. 5. Plant strategies Avoid Only grow during dryer seasons. Tolerate Grow roots above the water table. Grow tissue that helps to get oxygen into roots. Grow leafs and stems that are adapted to survive under water.
  6. 6. Root adaptations Aerenchyma – Long interconnected gas-filled chambers. – Pathway for gas to diffuse from leaves to roots. – Allows aerobic respiration to continue in the roots. – Allows oxygenation of the soil surrounding roots.
  7. 7. Root adaptations Adventitous roots – Roots that grow above the soil. Shallow roots Pneumatophores – root tips that stick up from the soil surface.
  8. 8. Shoot adaptations Shoot elongation – Removes the shoots from complete submergence – Mechanism • loosening of cell walls • Intake of water • Synthesis of new polysaccharides – Reduces the health of the plant once the water level recedes
  9. 9. Shoot adaptations Hyponastic growth – Growing leaves and shoots more vertically. – Helps to implement the effectiveness of shoot elongation. Submerged leaves – Thinner cuticles – Longer – Physiological changes to cells
  10. 10. Signalling and hormones Regulate the responses of plants to waterlogging and flooding Ethylene – most important Gibberellic acid Abscisic acid Hormones are interdependent – Ethlyene decreases abscisic acid concentrations which leads to an increase in gibberellic acid
  11. 11. Summary Main problems of water logging and flooding – low oxygen in soil, gas diffusion in flooding Avoid or tolerate Low soil O₂ - aerenchyma formation Flooding – shoot elongation, hyponastic growth Ethylene is main regulator response to flooding
  12. 12. References Armstrong, W., Brandle, R. & Jackson M. B. 1994, ‘Mechanisms of flood tolerances in plants’, Acta Botanica Neerlandica, vol. 43, pp. 307- 358. Blom, C., Voesenek, L., Banga, M., Engelaar, W., et al. 1994, ‘Physiological ecology of riverside species: adaptive responses of plants to submergence’, Annals of Botany, vol. 74, pp. 253-263. Blom, C. & Voesenek, L. 1996, ‘Flooding: the survival strategies of plants’, Trends in ecology and evolution, vol. 11, no. 7, pp. 290-295. Cosgrove, D. J. 1999, ‘Enzymes and other agents that enhance cell wall extensibility’, Annual Review of Plant Physiology and Plant Molecular Biology, vol. 50, pp. 391-417. Cox, M., Benchop, J. J., Vreeburg, R., Wagemaker, C., Moritz, T. et al. 2004, ‘The roles of ethylene, auxin, abscisic acid and gibberellin in the hyponastic growth of submerged Rumex palustris petioles. Plant Physiology, vol. 136, pp. 2948-2960. Groeneveld, H. W., Voesenek, L. 2003, ‘Submergence induced petiole elongation in Rumex palustris is controlled by developmental stage and storage compounds’. Plant and Soil, vol. 253, pp. 115-123. Jackson, M. B. 1990, Hormones and developmental change in plants subjected to submergence or soil waterlogging, Aquatic Botany, vol. 38, pp. 49-72. Koch, M. S. & Mendelssohn, J. A. 1989, ‘Sulphide as a soil phytotoxin: differential responses in two marsh species’, Journal of Ecology, vol. 77, pp.565-578. Mommer, L., de Kroon, H., Pierik, R., Bogemann, G. M. & Visser, E. 2005, ‘A functional comparison of acclimation to shade and submergence of two terrestrial plant species’, New Phytologist, vol. 167, no. 1, pp. 197-206. Setter, T. L., Laureles, E. V. 1996, ‘The beneficial effect of reduced elongation growth on submergence tolerance of rice’, Journal of Experimental Botany, vol. 47, pp. 1551-1559. Voesenek, L. & Sasidharan, R. 2013, ‘Ethylene – and oxygen signalling – drive plant survival during flooding’, Plant Biology, vol. 15, no. 3, pp. 426-435.