Dynamics of concentrations and nutrient fluxes in the xylem of <i>Ricinus communis</i>– diurnal course, impact of nutrient availability and nutrient uptake

Herdel, K.; Schmidt, Patrick; Feil, Regina; Mohr, Alexander T.; Schurr, Ulrich

doi:10.1046/j.1365-3040.2001.00655.x

Cited by 56 publications

(41 citation statements)

References 41 publications

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“…5B), and K=K 0 varies nonmonotonically for both cases with minima the depths of which grow with increasing radius and positions of which move to lower I c with increasing pore radius. Although, in general, K=K 0 varies nonmonotonically with I c , it increases monotonically with I c in the physiological range of I c (2-50 mM; Schurr and Schulze, 1995;Herdel et al, 2001;Siebrecht et al, 2003) for the larger pore sizes.…”

Section: Resultsmentioning

confidence: 89%

Impact of Electroviscosity on the Hydraulic Conductance of the Bordered Pit Membrane: A Theoretical Investigation

Santiago¹,

Pagay²,

Stroock³

2013

PLANT PHYSIOLOGY

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In perfusion experiments, the hydraulic conductance of stem segments (K xylem ) responds to changes in the properties of the perfusate, such as the ionic strength (I c ), pH, and cationic identity. We review the experimental and theoretical work on this phenomenon. We then proceed to explore the hypothesis that electrokinetic effects in the bordered pit membrane (BPM) contribute to this response. In particular, we develop a model based on electroviscosity in which hydraulic conductance of an electrically charged porous membrane varies with the properties of the electrolyte. We use standard electrokinetic theory, coupled with measurements of electrokinetic properties of plant materials from the literature, to determine how the conductance of BPMs, and therefore K xylem , may change due to electroviscosity. We predict a nonmonotonic variation of K xylem with I c with a maximum reduction of 18%. We explore how this reduction depends on the characteristics of the sap and features of the BPM, such as pore size, density of chargeable sites, and their dissociation constant. Our predictions are consistent with changes in K xylem observed for physiological values of sap I c and pH. We conclude that electroviscosity is likely responsible, at least partially, for the electrolyte dependence of conductance through pits and that electroviscosity may be strong enough to play an important role in other transport processes in xylem. We conclude by proposing experiments to differentiate the impact of electroviscosity on K xylem from that of other proposed mechanisms.

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Section: Resultsmentioning

confidence: 89%

Impact of Electroviscosity on the Hydraulic Conductance of the Bordered Pit Membrane: A Theoretical Investigation

Santiago¹,

Pagay²,

Stroock³

2013

PLANT PHYSIOLOGY

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“…After 3 weeks, seedlings were transferred to an aeroponics system and grown for a further 5 weeks as described previously (Herdel et al, 2001). Growth conditions were 12/12-h photoperiod, PPFD 200 mmol m 22 s 21 at plant level (HL), 25°C, and 60% relative air humidity.…”

Section: Tobacco Xylem Sapmentioning

confidence: 99%

Cytokinin Import Rate as a Signal for Photosynthetic Acclimation to Canopy Light Gradients

et al. 2007

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Plants growing in dense canopies are exposed to vertical light gradients and show photosynthetic acclimation at the wholeplant level, resulting in efficient photosynthetic carbon gain. We studied the role of cytokinins transported through the transpiration stream as one of probably multiple signals for photosynthetic acclimation to light gradients using both tobacco (Nicotiana tabacum) and Arabidopsis (Arabidopsis thaliana). We show that substantial variation in leaf transpiration parallels the light gradient in tobacco canopies and experimental reduction of the transpiration rate of a leaf, independent of light, is sufficient to reduce photosynthetic capacity in both species, as well as transcript levels of the small subunit of Rubisco (rbcS) gene in Arabidopsis. Mass spectrometric analysis of xylem sap collected from intact, transpiring tobacco plants revealed that shaded leaves import less cytokinin than leaves exposed to high light. In Arabidopsis, reduced transpiration rate of a leaf in the light is associated with lower cytokinin concentrations, including the bioactive trans-zeatin and trans-zeatin riboside, as well as reduced expression of the cytokinin-responsive genes ARR7 and ARR16. External application of cytokinin to shaded leaves rescued multiple shade effects, including rbcS transcript levels in both species, as did locally induced cytokinin overproduction in transgenic tobacco plants. From these data, we conclude that light gradients over the foliage of a plant result in reduced cytokinin activity in shaded leaves as a consequence of reduced import through the xylem and that cytokinin is involved in the regulation of whole-plant photosynthetic acclimation to light gradients in canopies.

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“…Methods in which the whole root system is visible are typically based on artificial media such as paper pouches (Chen et al, 2011;Le Marié et al, 2014), three-dimensional (3D) gels (Iyer-Pascuzzi et al, 2010), and hydro-or aeroponics (Herdel et al, 2001). Results may thus not be directly transferable to plants grown in natural 3D soil environments (Gregory et al, 2003).…”

mentioning

confidence: 99%

Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging

et al. 2016

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Dynamics of concentrations and nutrient fluxes in the xylem of Ricinus communis– diurnal course, impact of nutrient availability and nutrient uptake

Abstract: ABSTRACT

Cited by 56 publications

References 41 publications

Impact of Electroviscosity on the Hydraulic Conductance of the Bordered Pit Membrane: A Theoretical Investigation

Impact of Electroviscosity on the Hydraulic Conductance of the Bordered Pit Membrane: A Theoretical Investigation

Cytokinin Import Rate as a Signal for Photosynthetic Acclimation to Canopy Light Gradients

Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging

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