Abstract
Starch accumulation and sucrose synthesis and export were measured in leaves of sugar beet (Beta vulgaris L.) during a period of prolonged irradiance in which illumination was extended beyond the usual 14-hour day period. During much of the 14-hour day period, approximately 50% of the newly fixed carbon was distributed to sucrose, about 40% to starch, and less than 10% to hexose. Beginning about 2 hours before the end of the usual light period, the portion of newly fixed carbon allocated to sucrose gradually increased, and correspondingly less carbon went to starch. By the time the transition ended, about 4 hours into the extension of the light period, nearly 90% of newly fixed carbon was incorporated into sucrose and little or none into starch. Most of the additional sucrose was exported. Gradual cessation of starch accumulation was not the result of a futile cycle of simultaneous starch synthesis and degradation. Neither was it the result of a decrease in the extractable activity of adenosine diphosphoglucose pyrophosphorylase or phosphoglucose isomerase, enzymes important in starch synthesis. Nor was there a notable change in control metabolites considered to be important in regulating starch synthesis. Starch accumulation appeared to decrease markedly because of an endogenous circadian shift in carbon allocation, which occurred in preparation for the usual night period and which diverted carbon from the chloroplast to the cytosol and sucrose synthesis.
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Selected References
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- Chatterton N. J., Silvius J. E. Photosynthate Partitioning into Starch in Soybean Leaves: I. Effects of Photoperiod versus Photosynthetic Period Duration. Plant Physiol. 1979 Nov;64(5):749–753. doi: 10.1104/pp.64.5.749. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fondy B. R., Geiger D. R. Diurnal Pattern of Translocation and Carbohydrate Metabolism in Source Leaves of Beta vulgaris L. Plant Physiol. 1982 Sep;70(3):671–676. doi: 10.1104/pp.70.3.671. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fondy B. R., Geiger D. R. Diurnal changes in allocation of newly fixed carbon in exporting sugar beet leaves. Plant Physiol. 1985 Aug;78(4):753–757. doi: 10.1104/pp.78.4.753. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fondy B. R., Geiger D. R. Effect of Rapid Changes in Sink-Source Ratio on Export and Distribution of Products of Photosynthesis in Leaves of Beta vulgaris L. and Phaseolus vulgaris L. Plant Physiol. 1980 Nov;66(5):945–949. doi: 10.1104/pp.66.5.945. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fondy B. R., Geiger D. R., Servaites J. C. Photosynthesis, Carbohydrate Metabolism, and Export in Beta vulgaris L. and Phaseolus vulgaris L. during Square and Sinusoidal Light Regimes. Plant Physiol. 1989 Feb;89(2):396–402. doi: 10.1104/pp.89.2.396. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fox T. C., Geiger D. R. Effects of decreased net carbon exchange on carbohydrate metabolism in sugar beet source leaves. Plant Physiol. 1984 Nov;76(3):763–768. doi: 10.1104/pp.76.3.763. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fredeen A. L., Hennessey T. L., Field C. B. Biochemical Correlates of the Circadian Rhythm in Photosynthesis in Phaseolus vulgaris. Plant Physiol. 1991 Sep;97(1):415–419. doi: 10.1104/pp.97.1.415. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Geiger D. R., Fondy B. R., Tucci M. A. A Method for Calculating Sucrose Synthesis Rates throughout a Light Period in Sugar Beet Leaves. Plant Physiol. 1988 Jul;87(3):776–780. doi: 10.1104/pp.87.3.776. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Geiger D. R., Shieh W. J., Lu L. S., Servaites J. C. Carbon Assimilation and Leaf Water Status in Sugar Beet Leaves during a Simulated Natural Light Regimen. Plant Physiol. 1991 Nov;97(3):1103–1108. doi: 10.1104/pp.97.3.1103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Geiger D. R., Tucci M. A., Serviates J. C. Glyphosate effects on carbon assimilation and gas exchange in sugar beet leaves. Plant Physiol. 1987 Oct;85(2):365–369. doi: 10.1104/pp.85.2.365. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gerhardt R., Stitt M., Heldt H. W. Subcellular Metabolite Levels in Spinach Leaves : Regulation of Sucrose Synthesis during Diurnal Alterations in Photosynthetic Partitioning. Plant Physiol. 1987 Feb;83(2):399–407. doi: 10.1104/pp.83.2.399. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kruckeberg A. L., Neuhaus H. E., Feil R., Gottlieb L. D., Stitt M. Decreased-activity mutants of phosphoglucose isomerase in the cytosol and chloroplast of Clarkia xantiana. Impact on mass-action ratios and fluxes to sucrose and starch, and estimation of Flux Control Coefficients and Elasticity Coefficients. Biochem J. 1989 Jul 15;261(2):457–467. doi: 10.1042/bj2610457. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pongratz P., Beck E. Diurnal oscillation of amylolytic activity in spinach chloroplasts. Plant Physiol. 1978 Nov;62(5):687–689. doi: 10.1104/pp.62.5.687. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rao I. M., Fredeen A. L., Terry N. Leaf Phosphate Status, Photosynthesis, and Carbon Partitioning in Sugar Beet: III. Diurnal Changes in Carbon Partitioning and Carbon Export. Plant Physiol. 1990 Jan;92(1):29–36. doi: 10.1104/pp.92.1.29. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Servaites J. C., Fondy B. R., Li B., Geiger D. R. Sources of Carbon for Export from Spinach Leaves throughout the Day. Plant Physiol. 1989 Jul;90(3):1168–1174. doi: 10.1104/pp.90.3.1168. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Servaites J. C., Geiger D. R. Effects of light intensity and oxygen on photosynthesis and translocation in sugar beet. Plant Physiol. 1974 Oct;54(4):575–578. doi: 10.1104/pp.54.4.575. [DOI] [PMC free article] [PubMed] [Google Scholar]