External Pressures Based on Leaf Water Potentials Do Not Induce Xylem Sap to Flow at Rates of Whole Plant Transpiration from Roots of Flooded or Well-drained Tomato and Maize Plants. Impact of Shoot Hydraulic Resistances

Tiekstra, A.

doi:10.1006/anbo.2000.1193

Cited by 16 publications

(11 citation statements)

References 29 publications

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“…In turn, the impaired function of waterlogged roots would reduce the supply of water for the shoot, indirectly impacting on its growth and physiology via hydraulic signals (Birner & Steudle ; Tiekstra et al . ). In addition, the stressed root generates hormonal signals ( e.g.…”

Section: Discussionmentioning

confidence: 97%

Phenomic networks reveal largely independent root and shoot adjustment in waterlogged plants of Lotus japonicus

Striker

Casas

Manzur

et al. 2014

Plant Cell & Environment

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Waterlogging imposes severe stress to the plant, and the interplay between root and aerial organs in the adjustment to this stress is poorly understood. A set of recombinant inbred lines (RILs) of Lotus japonicus (Gifu B-129 × Miyakojima MG-20) was subjected to control and waterlogging conditions for 21 d, and 12 traits related to leaf physiological functioning, root aerenchyma formation, shoot and root morphology, and dry mass accumulation were assessed to generate phenomic networks. The phenomic network became more complex under waterlogging as a result of the incorporation of root aerenchyma and dark-adapted Fv/Fm. Significant waterlogging-induced variation was found for stomatal conductance, dark-adapted Fv/Fm and aerenchyma. The RILs with stronger induction of aerenchyma in response to waterlogging tended to show reduced negative impact of this stress on root growth but suffered average impact on shoot growth. The RILs that retained higher stomatal conductance under waterlogging tended to retain higher dark-adapted Fv/Fm and shoot growth under waterlogging conditions but showed average impact on root traits. We propose a model where, although the stress experienced by the roots during waterlogging is transmitted to the shoot, shoots and roots deal with waterlogging in a less interdependent manner than often assumed.

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Section: Discussionmentioning

confidence: 97%

Phenomic networks reveal largely independent root and shoot adjustment in waterlogged plants of Lotus japonicus

Striker

Casas

Manzur

et al. 2014

Plant Cell & Environment

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show abstract

“…The development of water potential gradients in the root system presumes the existence of significant axial resistances along the hydraulic path in the root system. Increased flow induced by pneumatic pressure in detopped roots of maize and tomato ( Lycospermum esculentum L.) suggests that axial resistance affects markedly sap flow (Tiekstra, Else, & Jackson 2000). Without these axial resistances, the water potential gradients along the roots would vanish.…”

Section: Discussionmentioning

confidence: 99%

Water uptake profile response of corn to soil moisture depletion

Fuchs

Cohen

et al. 2002

Plant Cell & Environment

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The effects of soil moisture distribution on water uptake of drip-irrigated corn were investigated by simultaneously monitoring the diurnal evolution of sap flow rate in stems, of leaf water potential, and of soil moisture, during intervals between successive irrigations. The results invalidate the steady-state resistive flow model for the continuum. High hydraulic capacitance of wet soil and low hydraulic conductivity of dry soil surrounding the roots damped significantly diurnal fluctuations of water flow from bulk soil to root surface. By contrast, sap flow responded directly to the large diurnal variation of leaf water potential. In wet soil, the relation between the diurnal courses of uptake rates and leaf water potential was linear. Water potential at the root surface remained nearly constant and uniformly distributed. The slope of the lines allowed calculating the resistance of the hydraulic path in the plant. Resistances increased in inverse relation with root length density. Soil desiccation induced a diurnal variation of water potential at the root surface, the minimum occurring in the late afternoon. The increase of root surface water potential with depth was directly linked to the soil desiccation profile. The development of a water potential gradient at the root surface implies the presence of a significant axial resistance in the root hydraulic path that explains why the desiccation of the soil upper layer induces an absolute increase of water uptake rates from the deeper wet layers.

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“…Although this phenomenon likely also affected determinations of ABA concentration in sap flowing from the root system, removal of the whole shoot while the root system was pressurised resulted in sap flow rates that greatly exceeded whole plant transpiration rate (Figure 4b) as previously reported [24]. This required sequential decreases in pneumatic pressure (Figure 2a) to collect root xylem sap at flow rates approximately equivalent to whole plant transpiration, for further analysis of ABA and related compounds.…”

Section: Discussionmentioning

confidence: 61%

Xylem sap collection and extraction methodologies to determine in vivo concentrations of ABA and its bound forms by gas chromatography-mass spectrometry (GC-MS)

2012

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BackgroundAccurate quantification of xylem sap ABA concentrations is important to underpin models of root-to-shoot ABA signalling to predict the physiological effects of soil drying. Growing tomato plants in a whole plant pressure chamber allowed sequential xylem sap collection from a detached leaf, the petiole stub of an otherwise intact plant and finally the de-topped root system of the same plant, to determine the impact of xylem sap sampling methodology on xylem ABA concentration. Since xylem sap can contain bound forms of ABA, a novel gas chromatography-mass spectrometry (GC-MS) procedure was developed to chemically separate free ABA from two in planta bound ABA forms known as Adducts I and II and ABA-glucose-ester (ABA-GE).ResultsXylem sap ABA concentrations were highly dependent on the sampling methodology used: the highest concentrations were detected in sap collected by applying an overpressure to detached leaves following the measurement of leaf water potential. Irrespective of xylem sap source, the wild-type cultivars Ailsa Craig and Rheinlands Ruhm had higher free ABA concentrations than a range of ABA-deficient mutants (notabilis, flacca and sitiens). However, in the mutants, concentrations of bound forms of ABA were similar to wild-type plants, and similar to free ABA concentrations.ConclusionsAlthough xylem concentrations of these bound ABA forms and ABA-GE suggest they have a limited physiological impact on ABA homeostasis in tomato, the methods developed here will allow a more complete understanding of ABA biochemistry and root-to-shoot signalling in species known to have higher concentrations of these compounds.

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External Pressures Based on Leaf Water Potentials Do Not Induce Xylem Sap to Flow at Rates of Whole Plant Transpiration from Roots of Flooded or Well-drained Tomato and Maize Plants. Impact of Shoot Hydraulic Resistances

Cited by 16 publications

References 29 publications

Phenomic networks reveal largely independent root and shoot adjustment in waterlogged plants of Lotus japonicus

Phenomic networks reveal largely independent root and shoot adjustment in waterlogged plants of Lotus japonicus

Water uptake profile response of corn to soil moisture depletion

Xylem sap collection and extraction methodologies to determine in vivo concentrations of ABA and its bound forms by gas chromatography-mass spectrometry (GC-MS)

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