Light and Translocation of C<sup>14</sup> in Detached Blades of Sugarcane

Hartt, Constance E.

doi:10.1104/pp.40.4.718

Cited by 44 publications

(19 citation statements)

References 11 publications

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“…Suiperimposed tiponl the general mass transport moving along a pressLure gradient, possibly the only mechanism by night but also operativ-e by day, is the special process of phototranslocation, a light-stimuilated process which speeds tip tralnslocation by day, is independent of stigar gradients, and cautses the accuimullatioll of sucrose at the sink (13,14,17).…”

Section: I3lant Physiology Discussionmentioning

confidence: 99%

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Hartt

1967

Plant Physiol.

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Summa111101ryA. Low moistuire suLpply, controlledl by 3 methods (addiing NaCl to a complete nuttrieint soluition, allowing a cuit stalk to wilt, or withholding irrigation in the fiekl), decreased the -elocity and percentage rate of translocation of 14C-photosynthate. The suirpluis suicrose not use(d in growth movedl more slowly in the phloem ani(d was stored in the stalk.Low moistuire stipply depressed translocationi of 14C-photosynthate more severely thanl it cuirtailed formation of 14C-photosNvnthate in the same leaf: therefore, the effect of moisture supply ulpoII translocation was primary.Low moistuire stupply retarded profile (levelopment in the stem, anid a loss in moistuire gradieint was associated with a steepened slope of the profile. These resuilts inclicate a flow mechanism of translocatioin rather than d(ifflusion.Resuilts reported now aild previouisly point to the operatioil of a slow pressulreflow mechanism particuilarl) duiring the night buit also during the day; suiperimpose(I upoIn this geineral mass tranisport is the more rapid process of phototranslocation which is indepenldent of suigar gra(lients anid which cani cauise the accuimuilationi of suIcrose at the storage-siink.DuIring ripeniing, storage of stucrose in the stalk may be increase(l by withholdlilng water because less sucrose is hydrolyzed in transit, less is uised in growth, and the slowly moving sucrose has more time for pa renchyma. (28,34,36,37,38

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Section: I3lant Physiology Discussionmentioning

confidence: 99%

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Hartt

1967

Plant Physiol.

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“…Another paper (11) reports defoliation tests which indicated that a major force in translocation resides within the leaf. The present paper clescribes experiments with detached blades which were started in 1960 (9). Harvesting and processing entire plants of sugarcane involve considerable time and work.…”

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Sugar Gradients and Translocation of Sucrose in Detached Blades of Sugarcane

Hartt

Kortschak

1964

Plant Physiol.

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“…A ntumber o,f studies have shown that organic transloecation from a leaf decreases as a result of darkening (3,7, 10, 11,12,13,18). Alithough the produiction of pholtosynthate ceases at the end of the light period, sizable amounts of sucrose and insoluble reserves are present in the leaf in addition to the material accumullated along the translocation path and in storage organs (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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Light and Translocation of C¹⁴ in Detached Blades of Sugarcane

Cited by 44 publications

References 11 publications

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Sugar Gradients and Translocation of Sucrose in Detached Blades of Sugarcane

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness

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Light and Translocation of C14 in Detached Blades of Sugarcane

Cited by 44 publications

References 11 publications

Effect of Moisture Supply upon Translocation and Storage of 14C in Sugarcane

Effect of Moisture Supply upon Translocation and Storage of 14C in Sugarcane

Sugar Gradients and Translocation of Sucrose in Detached Blades of Sugarcane

Translocation of 14C Sucrose in Sugar Beet during Darkness

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Light and Translocation of C¹⁴ in Detached Blades of Sugarcane

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Effect of Moisture Supply upon Translocation and Storage of ¹⁴C in Sugarcane

Translocation of ¹⁴C Sucrose in Sugar Beet during Darkness