Secretory Activity of the Root Cap

Rougier, M.

doi:10.1007/978-3-642-68234-6_22

Cited by 70 publications

(45 citation statements)

References 96 publications

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“…At the tip of every growing root is a conical covering consisting of several layers of cells called the root cap that plays a major role in root protection and its interaction with the rhizosphere (Rougier, 1981;Baluška et al, 1996;Barlow, 2003).…”

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The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

et al. 2009

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Border-like cells are released by Arabidopsis (Arabidopsis thaliana) root tips as organized layers of several cells that remain attached to each other rather than completely detached from each other, as is usually observed in border cells of many species. Unlike border cells, cell attachment between border-like cells is maintained after their release into the external environment. To investigate the role of cell wall polysaccharides in the attachment and organization of border-like cells, we have examined their release in several well-characterized mutants defective in the biosynthesis of xyloglucan, cellulose, or pectin. Our data show that among all mutants examined, only quasimodo mutants (qua1-1 and qua2-1), which have been characterized as producing less homogalacturonan, had an altered border-like cell phenotype as compared with the wild type. Border-like cells in both lines were released as isolated cells separated from each other, with the phenotype being much more pronounced in qua1-1 than in qua2-1. Further analysis of border-like cells in the qua1-1 mutant using immunocytochemistry and a set of anti-cell wall polysaccharide antibodies showed that the loss of the wild-type phenotype was accompanied by (1) a reduction in homogalacturonan-JIM5 epitope in the cell wall of border-like cells, confirmed by Fourier transform infrared microspectrometry, and (2) the secretion of an abundant mucilage that is enriched in xylogalacturonan and arabinogalactan-protein epitopes, in which the cells are trapped in the vicinity of the root tip.

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The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

et al. 2009

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“…Although knowledge of the chemitions have been attributed to root cap mucilage, cal composition of mucilages is certainly important, including the maintenance of root-soil contact, more knowledge of their physical properties is lubrication of the root tip, protection of roots from required if we are to obtain direct evidence regarding desiccation and disease, stabilization of soil micro-the function of mucilages in the rhizosphere. Guinel aggregates and the selective absorption and storage & McCully (1986) measured the d. wt (0-1 %) and of ions (Oades, 1978;Rougier, 1981). An under-water potential (-7-3 kPa) of root-cap mucilage standing of the chemical and physical characteristics from axenically grown maize seedlings.…”

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Surface tension and viscosity of axenic maize and lupin root mucilages

1997

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SUMMARYIn many plants, mucilage permeates the interface between root and soil, yet little is known about its physical properties or its infiuence on the physical properties of the rhizosphere. Mucilage was collected from 3-4-d-old, axenically-grown maize {Zea mays L. cv. Freya) and lupin {Lupinus angustifolius L. cv. Merrit) seedlings. Surface tension and viscosity were measured over a range of mucilage hydration, and neutral sugar analyses of the hydrolysed mucilages were obtained by gas chromatography. Surface tension of both maize and lupin mucilage was reduced to ~ 48 mN m"^ at total solute concentrations > 0-7 mg mr\ indicating the presence of powerful surfactants. Mucilage viscosity increased with increasing solute concentration and decreasing temperature. At a total solute concentration of 07 mg mr\ the viscosity of maize mucilage at 20 °C w^as 2-1 mPa s (approx. double that of pure water), increasing to 3-3 mPa s at 5 °C. Both maize and lupin mucilage showed viscoelastic behaviour. The major component of maize mucilage was found to be glucose, but in lupin it was fucose.The surface tension and viscosity results support the idea that mucilage plays a major role in the maintenance of root-soil contact in drying soils. As surface tension decreases, the ability of the mucilage to w^et the surrounding soil particles becomes greater. Also, as viscosity and elasticity increase, the resistance to movement of any soil particles in contact with the mucilage increases, a degree of stabilization of the rhizosphere structure is achieved and hydraulic continuity is maintained. It is unclear whether the surfactant is actively secreted by the root or is present simply as a result of leakage from root cells.

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“…Root caps of many plant species shed cells that become part of a mucilaginous sheath that surrounds the growing root (24). These shed cells, thought to be a by-product of root cap turnover, have traditionally been referred to as "sloughed" root cap cells because of the belief that the cells were dead (21,24,28).…”

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Correlation of Pectolytic Enzyme Activity with the Programmed Release of Cells from Root Caps of Pea (Pisum sativum)

Hawes¹,

Lin²

1990

Plant Physiol.

105

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In many plant species, the daily release of hundreds to thousands of healthy cells from the root cap into the soil is a normal process, whose function is unknown. We studied the separation of the cells in pea (Pisum sativum) using an aeroponic system in which separated cells were retained on the root until they were washed off for counting. We found that cell separation is a developmentally regulated, temperature-sensitive process that appears to be regulated independentiy of root growth. No cells were released from very young roots. When plants were grown aeroponically, cell numbers increased with increasing root length to a mean of 3400 cells per root, at which point the release of new cells ceased. The process could be reset and synchronized by washing the root in water to remove shed cells. Cell separation from the root cap was correlated with pectolytic enzyme activity in root cap tissue. Because these cells that separate from the root cap ensheath the root as it grows and thus provide a cellular interface between the root surface and the soil, we propose to call the cells "root border cells."

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Secretory Activity of the Root Cap

Cited by 70 publications

References 96 publications

The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

The Organization Pattern of Root Border-Like Cells of Arabidopsis Is Dependent on Cell Wall Homogalacturonan

Surface tension and viscosity of axenic maize and lupin root mucilages

Correlation of Pectolytic Enzyme Activity with the Programmed Release of Cells from Root Caps of Pea (Pisum sativum)

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