Synthesis and Dissolution of Starch labelled with<sup>14</sup>Carbon in Tobacco Leaf Tissue

Porter, H. K.; Martín, R. V.; Bird, I. F.

doi:10.1093/jxb/10.2.264

Cited by 28 publications

(12 citation statements)

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“…The lowering of sucrose specific activity by the contribution from polysaccharide reserves could be the resulit of simultaneous dissolution of both newly synthesized, labeled layers and layers from older grains which were completed prior to labeling (21). Tihis view is supported by an electron microscope study of the source leaf which reveals that as i'llutmination continuies, starch grains stop growing -in size and new grains begin to form (Giesv and Geiger, unpubltished).…”

Section: Resultsmentioning

confidence: 99%

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“…In the present study, our attention is centtered on adjustments which occur during the conversion from light-period to dark-,period translocation. Several studies have investigated leaf metabolite pools following darkening (6,21) specif:c activity of the stugar was comlpared with the specif.c activity of the su,pplied CO., obtained by measturing the rate of uiptake of CO., and "COfrom the gas stream circulating over the suipply leaf. The latter measuirements were made with a LIRA infrared gas analyzer and a Dynaconi ioni chalmber svstem (10).…”

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Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Geiger

Batey

1967

Plant Physiol.

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Sutmmary. The time-course of arrival of '4C translocate in a sink leaf was studied in sugar beet (Beta vulgaris L. cultivar Klein Wanzleben) for up to 480 minutes of darkness. Following darkening of the source leaf, translocation rapidly declined, reaching a rate approximately 25 % of the light period rate by 150 minutes. Com-parison of d-ata from plants that were girdled 1 cm below the crown with data from ungirdled plants indicates that after about 150 minutes darkness the beet root becomes a source of translocate to the sink leaf. After aboutt 90 minutes darkness, starch-like reserve polysacchariide from the source leaf begins to contribute 14C to ethanol soluble pools in that leaf. Because of a 15 % isoltope mass effect, sucrose, at isotopic saturation, reaches a specific activity which is about 85 % of the level of the supplied CO2. The souirce leaf sucrose specific activity remains at the isotopic saturation level for about 150 minutes of darkness, after which time input from polysaccharide reserves causes the specific activity to drop to about 55 % of that of the supplied CO2. Sucrose specific activity determinations, polysaccharide di ssoltution measurements, and pulse labeliing experiments indicate that following partial depletion of the sucrose pool, source leaf polysaccharide contributes to dark translocation. Respired CO2 from the pool which, unlike sucrose, remains at a to a simple source-path-sink system consisting of a mature source leaf and a small sink leaf attached to the beet and root system. Plants were grown by solution culture in controlled environment eabinets as described earlier (9, 10). In some experiments, a 1-cm zone of the beet, located 2 cm below the crown, was killed by heating it with a hot nichrome wire for 5 to 6 minutes. The heat was localized by a pair of asbestos shields fitted over the horizontally positioned beet. Heat girdling was performed 18 hours before labeling to allow time for desiccation. No wilting was noted in contrast to the occasional wilting following steam girdling, and essentially no radioactivity above background was found distal to the girdle. To determine the 14C content of various compounds in the source leaf, the entire leaf or a known portion constituting up to 25 % of the blade area was sampled. Extraction and chromatographic scanning methods for sucrose, glucose, and fructose have been reported previously (9). For specific activity determination, sugars from a 10 to 50 ml aliquot of the 80 % (v/v) ethanol extract of the supply leaf were separated by ion exchange chromatography on a 0.8 X 20 cm AG 1 X 8 borateform ion exchange column (16).The chloroform-extracted sample was reduced to 2 ml and adjusted to a concentration of 5 mM sodium borate before being added to the column. The sucrose, eluted with 5 mm soidium borate was generally present in the 40 to 100 ml fractions.source leaf appears to be derived from a uniform specific activiity.A ntumber o,f studies have shown that organic transloecation from a leaf decreases as a result of darkening (3,7, 10...

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Section: Resultsmentioning

confidence: 99%

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Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Geiger

Batey

1967

Plant Physiol.

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“…Gibbs (1951) found in sunflower leaves a dextrin fraction, soluble in lO% ethanol, that rapidly incorporated 14C0 2 • From radiochemical evidence Porter, Martin, and Bird (1959) have suggested that in tobacco leaves a starch-like polysaccharide, which does not undergo the same metabolism as starch, is synthesized. A search has been made for these products in tobacco leaves (cv.…”

Section: ·040mentioning

confidence: 99%

“…The starch deposition in wheat grains, and presumably other storage organs, is not extensively reversible as shown by radiochemical evidence (McConnell, Mitra, and Perlin 1958). In leaves it is more readily metabolized (Porter 1953;Porter, Martin, and Bird 1959;Tsin-Tze Chan and Bird 1960), showing a diurnal rhythm and acting as an energy reserve for the living plant (Fischer 1958;Wanner 1958). Thus in leaves, starch is transient and if any changes in the structure of starch accompany its metabolism then these could be more readily detected in leaf starch than in the starch of storage organs.…”

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confidence: 99%

Starch Changes in Developing and Senescing Tobacco Leaves

Matheson¹,

Wheatley²

1962

Aust. Jnl. Of Bio. Sci.

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SummaryThe quantitative changes in starch content during the growth and senescence of tobacco leaves have been followed. The starch content was low while the leaves were expanding but rapidly increased after expansion stopped. The maximum was reached when more than half of the original chlorophyll content had gone. The starch content was then reduced rapidly and when the leaf was all yellow there was only a small quantity of starch and this remained when the leaf turned brown.The viscosities, iodine affinities, fl-amylolysis limits, and granule sizes of isolated starch granules and the chain lengths of amylopectins at different ages of leaves have been determined. The viscosities and iodine affinities increased with increasing age of the leaf and the fl-amylolysis limits of the whole starch and chain length of the amylopectins were constant throughout the growth of the leaf. The average granule size increased as the leaf matured until maximum starch content was reached and decreased as the starch content decreased. It is suggested that in tobacco leaves another starch accumulation pattern of longer duration than 'diurnal accumulation exists. The degradation of the starch resembles the breakdown of starch in sprouting potato tubers and not that in germinating barley where amylases are the active enzymes.The residue after ethanol extraction of leaves at different stages of growth was fractionated into water-soluble material, a perchloric acid extract precipitated by iodine, and a perchloric acid extract not precipitated by iodine but precipitated by ethanol. Glucan was present in significant concentration only in the perchloric acid extract precipitated by iodine and this had the properties of starch. Paper chromatography indicated that non-starchy extracts were composed of galactose, arabinose, xylose, rhamnose, and uronic acid.

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Neuere Beiträge zur Chemie der Stärkefraktionen. XI. Die Herstellung von mit C¹⁴ markierter Stärke und von Glucose‐1‐Phosphat

Holló¹,

Szejtli²,

László³

et al. 1962

Starch Stärke

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Synthesis and Dissolution of Starch labelled with¹⁴Carbon in Tobacco Leaf Tissue

Cited by 28 publications

References 6 publications

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Starch Changes in Developing and Senescing Tobacco Leaves

Neuere Beiträge zur Chemie der Stärkefraktionen. XI. Die Herstellung von mit C¹⁴ markierter Stärke und von Glucose‐1‐Phosphat

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Synthesis and Dissolution of Starch labelled with14Carbon in Tobacco Leaf Tissue

Cited by 28 publications

References 6 publications

Translocation of 14C Sucrose in Sugar Beet during Darkness

Translocation of 14C Sucrose in Sugar Beet during Darkness

Starch Changes in Developing and Senescing Tobacco Leaves

Neuere Beiträge zur Chemie der Stärkefraktionen. XI. Die Herstellung von mit C14 markierter Stärke und von Glucose‐1‐Phosphat

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Synthesis and Dissolution of Starch labelled with¹⁴Carbon in Tobacco Leaf Tissue

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

Neuere Beiträge zur Chemie der Stärkefraktionen. XI. Die Herstellung von mit C¹⁴ markierter Stärke und von Glucose‐1‐Phosphat