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Hydraulic Architecture of Vascular Plants

Steudle, Ernst Lüttge, Ulrich (Editor) ; Beck, Erwin (Editor) ; Bartels, Dorothea (Editor)

Ecological Studies, Plant Desiccation Tolerance, pp.185-207

Berlin, Heidelberg: Springer Berlin Heidelberg 2011

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  • Título:
    Hydraulic Architecture of Vascular Plants
  • Autor: Steudle, Ernst
  • Lüttge, Ulrich (Editor) ; Beck, Erwin (Editor) ; Bartels, Dorothea (Editor)
  • Assuntos: Life Sciences ; Plant Ecology ; Plant Physiology ; Plant Genetics & Genomics ; Plant Biochemistry ; Plant Anatomy/Development ; Botany
  • É parte de: Ecological Studies, Plant Desiccation Tolerance, pp.185-207
  • Descrição: When vascular plants are subjected to drought and eventually desiccate, they use different mechanisms to protect against water losses. Within the liquid phase, changes in hydraulics refer to part of these mechanisms of stress avoidance, which exclude the major role of gas exchange. At the input side, the water uptake by plant roots is governed by the composite structure of roots, which provides different pathways across the root cylinder. These are affected by the action of aquaporins (AQPs) in the cell membranes and apoplastic barriers along the cell wall path. The composite transport model is shown to provide mechanisms of short-term adaptation to water shortage. Composite transport and apoplastic barriers in roots should also be involved during the rehydration of resurrection plants, but this was not yet considered. Long-distance transport in the xylem according to the cohesion/tension (CT) mechanism is subject to cavitation, although xylem can withstand rather large tensions before vessels embolize. The problem is the refilling, where mechanisms have been proposed, but clues for solving the problem are missing. It is pointed out that, in resurrection plants, mechanisms of refilling appear to be more simple in that there is no refilling of empty xylem in the presence of a surrounding that has a water potential, which is more negative than that within the vessels. In the leaf, the major constraint with respect to hydraulic conductance is again cavitation, but detailed quantitative measurements are missing here to really provide physical models of the leaf hydraulic architecture. In both stem flow and leaf hydraulics, the role of living cells of xylem parenchyma is much discussed not only during refilling, but also during uptake and loss of water into or from vessels. Evidence for the action of AQPs in living tissue around xylem vessels comes from the temperature and light dependence of shoot hydraulic conductivity, which are hard to understand in terms of just viscose flow across vessels.
  • Editor: Berlin, Heidelberg: Springer Berlin Heidelberg
  • Data de publicação: 2011
  • Idioma: Inglês

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