Water Balance in the Onion Root: Relation of Volume Intake to Volume Exudate of Excised Roots and Isolated Root Segments

Rosene, Hilda F.

doi:10.1104/pp.16.3.447

Cited by 10 publications

(12 citation statements)

References 7 publications

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“…In addition it is probable that the root segments are exuding solution from both ends (e.g. Rosene 1941) and that this bulk flow would prevent diffusion of salt into the open ends of the stele.…”

Section: Discussion (A) Validity Of the Estimate Of Plasmalemma Imentioning

confidence: 99%

The Use of Short-Term and Quasi-Steady Influx in Estimating Plasmalemma and Tonoplast Influx in Barley Root Cells at Various External and Internal Chloride Concentrations

Cram¹,

Gg²

1971

Aust. Jnl. Of Bio. Sci.

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Ab8tractChloride influx measured with 36Cl over a 10 min loading period followed by a 5 min wash in inactive solution is used as an estimate of influx across the plasmalemma in barley roots. Chloride influx measured over a 60 min loading period followed by a 30 min wash is used as an estimate of the quasi-steady influx from the external solution to the vacuole.The 10 min load, 5 min wash flux estimate is shown not to be in error due to inclusion of extracellular contents in the root cortex or in the stele. It therefore appears to be a good estimate of the influx across the plasmalemma of the cortical cells.At external chloride concentrations below about 5 mM the plasmalemma influx and the influx to the vacuole are approximately equal, and therefore the influx across the plasmalemma appears to be the rate-limiting step in the influx of chloride to the vacuole. At external chloride concentrations above about 10 mM the plasmalemma influx increases nearly linearly with external chloride concentration to very high values at 80 mM, whereas the influx to the vacuole does not increase above 20-30 mM. The "saturation" in influx to the vacuole at high external chloride concentrations therefore appears to be determined by the saturation of transport across the tonoplast or of a transport process directly through the cytoplasm to the vacuole, in confirmation of the conclusion of Torii and Laties (1966).Some observations suggest that part of the fluxes across the plasmalemma are mediated by exchange diffusion.In salt-loaded tissue the plasmalemma influx and the influx to the vacuole are both reduced. This apparent negative feedback relationship between chloride content and influx of chloride is briefly discussed.

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Section: Discussion (A) Validity Of the Estimate Of Plasmalemma Imentioning

confidence: 99%

The Use of Short-Term and Quasi-Steady Influx in Estimating Plasmalemma and Tonoplast Influx in Barley Root Cells at Various External and Internal Chloride Concentrations

Cram¹,

Gg²

1971

Aust. Jnl. Of Bio. Sci.

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“…This demonstrates the existence of a mechanism in roots by which water content varies periodically, and it suggests a variable hydration of proto plasm. Inequalities between absorption and exudation of water by isolated onion roots [Rosene (24)] are probably a reflection of the same mechanism. This recalls the observation of Shreve (25) that regular diurnal changes in water-holding capacity of cactus tissue occur, the water-holding capacity being greater during the day than at night.…”

Section: Water Balance In Plant Cellsmentioning

confidence: 99%

Water Relations of Plant Cells and Tissues

Kramer¹,

Currier²

1950

Annu. Rev. Plant. Physiol.

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“…With rare exceptions, actual measurements of absorption have not been made, and the investigators have assumed that water absorption ceased when exudation ceased. Simultaneous measurements of both volume absorption and volume exudation, however, show that these are not necessarily equal in a given interval of time (Speidel, 1939;Rosene, 1941b); and absorption of water may occur in the absence of exudation (Rosene, unpublished).…”

mentioning

confidence: 99%

“…PROCEDuRE.-Detailed description of the technique will be omitted since it has already been published (Rosene, 1937(Rosene, , 1941(Rosene, a, 1941b. The data were obtained from roots of Allium cepa cultured in aerated solutions.…”

mentioning

confidence: 99%

“…The velocities of absorption during the initial control period when the potometers were filled with sucrose solution were determined immediately following excision. This may account for the relatively .100 X 3 u.. z low average rates of influx during the control period, since it has been shown that rates of water absorption increase with time after excision during a twenty-four-hour period (Rosene, 1941a). Complete absence of water absorption by all four regions in a single isolated root throughout the period of exposure to sucrose solution was not manifested; root V, however, showed that with 0.1 M sucrose solution, influx velocities in the regions at potometers 1, 2, and 3 were brought to zero while at potometer 4 a very low velocity of outfio-» was exhibited.…”

mentioning

confidence: 99%

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Control of Water Transport in Local Root Regions of Attached and Isolated Roots by Means of the Osmotic Pressure of the External Solution

Rosene

1941

American J of Botany

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Water Balance in the Onion Root: Relation of Volume Intake to Volume Exudate of Excised Roots and Isolated Root Segments

Cited by 10 publications

References 7 publications

The Use of Short-Term and Quasi-Steady Influx in Estimating Plasmalemma and Tonoplast Influx in Barley Root Cells at Various External and Internal Chloride Concentrations

The Use of Short-Term and Quasi-Steady Influx in Estimating Plasmalemma and Tonoplast Influx in Barley Root Cells at Various External and Internal Chloride Concentrations

Water Relations of Plant Cells and Tissues

Control of Water Transport in Local Root Regions of Attached and Isolated Roots by Means of the Osmotic Pressure of the External Solution

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