Metabolism of Radioactive Sugars by Tobacco leaf Disks

Porter, H. K.; May, LH

doi:10.1093/jxb/6.1.43

Cited by 66 publications

(21 citation statements)

References 22 publications

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“…Quite recently, it also has been found in tomato roots (6). In Table I, uptake ratios for sugars in tomato internodes have been compared with the uptake ratios into tobacco leaf discs (17), into immature internodal tissue of sugarcane (2), and into Nitella flexilis cells (24). It strengthens the assumption of Goring (10), that the capability to absorb sucrose intact is proper to dicotyledons.…”

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confidence: 82%

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Different Mass Transfer Rates of Labeled Sugars and Tritiated Water in Xylem Vessels and Their Dependency on Metabolism

Bel¹

1976

Plant Physiol.

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Solutions of '4C-sugars in tritiated water or solutions of 14C-and 3H-sugars were perfused by gravity through the xylem vessels of excised tomato internodes (Lycopersicon esculentum) mostly during 2 hours.Mass flow of a solution in plant vessels is found not to be in conflict with different mass trnsfer rates of sugar and water molecules. It is explained by individual lateral escape rates from the vessel for each single compound. The escape of tritiated water can be ascribed to diffusion, while the escape of sugars is apparently linked to the metabolism of the surrounding parenchyma cels (Q1o sucrose uptake = 3.5).

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confidence: 82%

“…This mechanism has been found to be functioning in sucrose uptake in other dicotyledons (12,17,18). Quite recently, it also has been found in tomato roots (6).…”

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confidence: 95%

Different Mass Transfer Rates of Labeled Sugars and Tritiated Water in Xylem Vessels and Their Dependency on Metabolism

Bel¹

1976

Plant Physiol.

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“…21) while in tobacco leaf discs sucrose is taken up unaltered (16). There are -reports of considerable invertase in the outer space of other higher plants (4.…”

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“…It appears that the presence of hexose increases the ratio of sucrose/origin compounds by providing a ready--source of miietabolic intermediates. For tobacco leaf discs part of the evidlenice used in concluding that sucrose was taken up without hydrolysis was the much lesser starch formation from exogenous sucrose than from glucose (16). Several points may be enumerated which provide evidence about cellular localization of sugar storage.…”

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confidence: 99%

The Regulation of Sugar Uptake and Accumulation in Bean Pod Tissue

Sacher

1966

Plant Physiol.

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Suomlmaitry. The identity, localization and physiological significance of enzymes in-\-olved in sugar uptake anid accumulationi were determined for endocarp tissue of pods of Kenitucky XVonder pole beans (Phaseolhs vulgaris). An intracellular, alkaline invertase (H optimum, 8) was assayed in extracted protein, as well as enzymes involved in -lcrose synthesis, namely, uridinediphosphate (UDP-glucose pyrophosphorylase and U DP-glucose-fructose transglucosylase). Indirect evidence indicated the presence also of hlexokinase, phosphohexoseisomerase and phosphoglucomutase. The data suggested tnat sucrose synthesis occurred in the cytoplasm, and that both sugar storage and an alkaline inlvertase occurred in the vacuole. The latter functions to hydrolyze accumulated sucrose An outer space invertase (pH optimum, 4.0) was detected, but was variable in occilrrence. Although its activity at the cell surface enhanced sucrose uptake. sucrose mav be taken up unaltered.Over

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“…A comparison, with similar tissue, of the proportion of the total activity associated with the particulate fraction after preparation by these two methods, coupled with an investigation into the rate of sucrose hydrolysis by the intact tissue, before and after treatment with ethyl acetate, may give a more reliable estimate of the proportion of the total acid invertase bound to the cell wall of leaves of oat. Nevertheless, the role of insoluble acid invertase in vivo has yet to be resolved as the uptake of sucrose into leaf discs of deadly nightshade (Weatherley, 1953), tobacco (Porter and May, 1955) and sugar beet (Giaquinta, 1977) does not appear to require prior hydrolysis external to the plasmalemma.…”

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confidence: 99%

The Acid Invertases of the Developing Third Leaf of Oat

Greenland

1981

New Phytologist

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SUMMARYChanges in activities of soluble and insoluble acid invertases and in concentrations of ethanol-soluble carbohydrates were examined during development of the third leaf of oat.The leaves did not contain any alkaline invertases. High activity of soluble invertase, high concentrations of reducing sugar and low concentrations of sucrose occurred in the non-emerged lamina, enclosed by the sheaths of older leaves. In the developing emerged region, activity of soluble invertase rapidly declined to a steady state in the mature leaf. In this tissue, the concentration of total soluble carbohydrate was initially low but increased as the leaf matured and sucrose was always the predominant sugar. The activity of insoluble acid invertase remained relatively constant throughout leaf development. When invertase activities and amounts of soluble carbohydrates were compared in apical and basal regions of the mature leaf after ligule emergence, higher levels of both soluble and insoluble invertase, and total soluble carbohydrates, occurred in the apical half of the leaf.

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Metabolism of Radioactive Sugars by Tobacco leaf Disks

Cited by 66 publications

References 22 publications

Different Mass Transfer Rates of Labeled Sugars and Tritiated Water in Xylem Vessels and Their Dependency on Metabolism

Different Mass Transfer Rates of Labeled Sugars and Tritiated Water in Xylem Vessels and Their Dependency on Metabolism

The Regulation of Sugar Uptake and Accumulation in Bean Pod Tissue

The Acid Invertases of the Developing Third Leaf of Oat

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