Some Compartmental Models of the Root: Steady-state Behavior

Murphy, Ricardo

doi:10.1006/jtbi.2000.2194

Cited by 6 publications

(7 citation statements)

References 45 publications

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“…Such flow regulation has recently been intensively documented for water crossing membranes via aquaporins (Maurel 1997, Johansson et al 1998). Evidence already exists showing that water flow through isolated roots is limited by the conductivity of aquaporins in the transcellular pathway in tomato (Maggio and Joly 1995) and a wide range of other plants including monocots, dicots, trees and legumes (Caravajal et al 1996, 2000, Henzler et al 1999, Kjellbom et al 1999, Quintero et al 1999, Wan and Zwiazek 1999. Therefore, the water flow kinetics we observed in isolated roots of tomato, pea, and soybean may be more amenable to facilitated passive diffusion and models based on enzyme kinetics (Emery and Salon 2001).…”

Section: An Hypothesis Based On Facilitated Passive Diffusionmentioning

confidence: 76%

“…However, testable predictions arising from the putative role of the phloem have yet to be investigated. Despite these problems, use of the model has perpetuated in many recent studies and reviews (Carvajal et al 1996, 2000, Jackson et al 1996, Fennel and Markhart 1998, Henzler et al 1999, Quintero et al 1999, Seel and Jeschke 1999, Tyerman et al 1999, Wan and Zwiazek 1999. Its apparent phenomenological fit but lack of physiological resolution for some of its parameters has prompted a description of the simple passive diffusion model and its ability to explain flow data as 'simple yet baffling' .…”

Section: The Ordinary Passive Diffusion Modelmentioning

confidence: 99%

“…Present results and problems with the current mathematical modelling of water uptake in pressurized roots could be reconciled mechanistically with facilitated passive diffusion and the existence of water channels, aquaporins, for transmembrane water entry into roots. Considerable physiological and molecular studies indicate flow is largely symplastic and that aquaporins may provide the greatest resistance to water flow through root systems (Markhart and Smit 1990, Maggio and Joly 1995, Carvajal et al 1996, 2000, Henzler et al 1999, Kjellbom et al 1999, Quintero et al 1999, Wan and Zwiazek 1999.…”

Section: An Hypothesis Based On Facilitated Passive Diffusionmentioning

confidence: 99%

“…Fiscus (1986) mathematically described diurnal changes in components of Equation 3, but the explanation was complex and the underlying physiological mechanism remained a black box. Murphy (2000) explained P off in a four‐component model incorporating asymmetric solute distribution across the endodermis as a result of phloem delivery of photoassimilates. However, testable predictions arising from the putative role of the phloem have yet to be investigated.…”

Section: Introductionmentioning

confidence: 99%

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Water entry into detached root systems saturates with increasing externally applied pressure; a result inconsistent with models of simple passive diffusion

Emery¹,

Salon²

2002

Physiologia Plantarum

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The most widely accepted model of radial water entry from the soil into the xylem of roots is based on principles of ordinary passive diffusion. However, long-standing problems with this model remain unresolved, which concern variable intrinsic properties of conductivity, Lp, changing reflection coefficients, sigma, and inaccurate resolution of osmotic differentials between the soil and xylem. Our study re-examined pressure flow relationships in isolated roots of tomato (Lycopersicon esculentum Mill. cv. Montfavet), pea (Pisum sativum cv. Baccara) and soybean (Glycine max L. Merryl cv. Essor) manipulated in a pressure chamber. In addition to problems previously recognized with the simple passive diffusion model, a new conflict, flow saturation, was observed at high pressures. Experiments revealed that the plateau in flow, Jmax seen at high pressures followed natural rhythms diurnally and developmentally, and was not due to root damage or unnatural flow restriction. Near the end of the photoperiod, Jmax closely correlated with root dry mass. The above inconsistencies between observations in pressure-flow kinetics and ordinary passive diffusion indicate that either the current model should be adjusted or a new model should be proposed.

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Section: An Hypothesis Based On Facilitated Passive Diffusionmentioning

confidence: 76%

Section: The Ordinary Passive Diffusion Modelmentioning

confidence: 99%

Section: An Hypothesis Based On Facilitated Passive Diffusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Water entry into detached root systems saturates with increasing externally applied pressure; a result inconsistent with models of simple passive diffusion

Emery¹,

Salon²

2002

Physiologia Plantarum

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“…A number of studies (cf. the review of Murphy, 2000) have taken this approach to understand the interplay between steady-state water and solute fluxes in nongrowing tissue: Such models explain the observed nonlinear relationship between flux and applied pressure.…”

Section: Hydraulics and Nutrient Transportmentioning

confidence: 99%

Multiscale Systems Analysis of Root Growth and Development: Modeling Beyond the Network and Cellular Scales

et al. 2012

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Over recent decades, we have gained detailed knowledge of many processes involved in root growth and development. However, with this knowledge come increasing complexity and an increasing need for mechanistic modeling to understand how those individual processes interact. One major challenge is in relating genotypes to phenotypes, requiring us to move beyond the network and cellular scales, to use multiscale modeling to predict emergent dynamics at the tissue and organ levels. In this review, we highlight recent developments in multiscale modeling, illustrating how these are generating new mechanistic insights into the regulation of root growth and development. We consider how these models are motivating new biological data analysis and explore directions for future research. This modeling progress will be crucial as we move from a qualitative to an increasingly quantitative understanding of root biology, generating predictive tools that accelerate the development of improved crop varieties.

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Primary root growth: a biophysical model of auxin-related control

Chavarría-Krauser

Jäger

Schurr

2005

Functional Plant Biol.

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Plant hormones control many aspects of plant development and play an important role in root growth. Many plant reactions, such as gravitropism and hydrotropism, rely on growth as a driving motor and hormones as signals. Thus, modelling the effects of hormones on expanding root tips is an essential step in understanding plant roots. Here we achieve a connection between root growth and hormone distribution by extending a model of root tip growth, which describes the tip as a string of dividing and expanding cells. In contrast to a former model, a biophysical growth equation relates the cell wall extensibility, the osmotic potential and the yield threshold to the relative growth rate. This equation is used in combination with a refined hormone model including active auxin transport. The model assumes that the wall extensibility is determined by the concentration of a wall enzyme, whose production and degradation are assumed to be controlled by auxin and cytokinin. Investigation of the effects of auxin on the relative growth rate distribution thus becomes possible. Solving the equations numerically allows us to test the reaction of the model to changes in auxin production. Results are validated with measurements found in literature.

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Some Compartmental Models of the Root: Steady-state Behavior

Cited by 6 publications

References 45 publications

Water entry into detached root systems saturates with increasing externally applied pressure; a result inconsistent with models of simple passive diffusion

Water entry into detached root systems saturates with increasing externally applied pressure; a result inconsistent with models of simple passive diffusion

Multiscale Systems Analysis of Root Growth and Development: Modeling Beyond the Network and Cellular Scales

Primary root growth: a biophysical model of auxin-related control

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