Storage of Starch

Jenner, CF

doi:10.1007/978-3-642-68275-9_20

Cited by 32 publications

(16 citation statements)

References 218 publications

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“…Potato tubers or cocoyam corms were sliced to 1 mm thickness, and discs 4 mm in diameter were cut from these slices under a medium containing 5 mM DTT and 33 mM PEG-4000. The discs were washed twice in fresh medium before 14 discs (containing about 10 mg starch) were added to each 10-mL vial. The 148 Bq/fmol).…”

Section: Methodsmentioning

confidence: 99%

“…The total starch content of the perchloric acid extract of a sample of discs was determined using the anthrone reagent (4). Results are expressed on a mg total starch basis, which is convertible to g fresh weight assuming 18% of potato tuber fresh weight is starch (14).…”

Section: Methodsmentioning

confidence: 99%

“…1), incorporation of '4C into the ethanolsoluble fraction did not continue after the first hour, and incorporation into starch proceeded at a rate about 5% of that observed with discs cut from developing tubers. The relatively slow incorporation of label into starch by the discs from dormant tubers may be attributable to a slow turnover of starch that can occur in mature tubers ( 14). At 21°C the rate of sucrose incorporation into starch by discs from developing tubers is equivalent to a daily growth rate of0.014 g fresh weight/g tuber fresh weight.…”

Section: Methodsmentioning

confidence: 99%

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Effect of Temperature on Starch Synthesis in Potato Tuber Tissue and in Amyloplasts

Mohabir¹,

John²

1988

Plant Physiol.

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A sharp temperature optimum is observed at 21.5°C when the incorporation of ["4Clsucrose into starch is measured with discs cut from developing tubers of potato (Solanum tuberosum L. cv Desiree). By contrast, increasing temperatures over the range 9 to 31°C only enhance release of '4C to respiratory CO2 and incorporation of '4C into the ethanolsoluble fraction. By comparison, starch synthesis in discs from developing corms of cocoyam (Colocasia esculenta L. Schott) is increased by raising the temperature from 15 to 35°C. The significance of a relatively low temperature optimum for starch synthesis in potato is discussed in relation to the yield limitations imposed by continuously high soil temperatures. Amyloplasts isolated from protoplasts prepared from developing potato tubers contain activities of alkaline pyrophosphatase, NADdependent glyceraldehyde-3-phosphate dehydrogenase, fructose-1,6-bisphosphatase, and phosphoglucomutase in addition to ADP-glucose-pyrophosphorylase, starch phosphorylase and starch synthase. Cell-free amyloplasts released by thinly slicing developing potato tubers synthesize starch from I'4Cltriose-phosphate generated from phosphate in the reaction medium. This starch synthesis is inhibited by addition of 10 millimolar inorganic phosphate and requires amyloplast integrity, suggesting the operation of a triose-phosphate/inorganic phosphate exchange carrier at the amyloplast membrane. The temperature optimum at 21.5°C observed with tissue discs is not observed with amyloplasts.The yield of potatoes in the warm tropics is limited by the continuously high soil temperatures (1). Growth of the potato tuber is closely linked to starch synthesis, and physiological studies with whole tubers still attached to the parent plant have indicated that higher temperatures could reduce yields by inhibiting starch synthesis in the tuber (17,24,28,33). However, interpretation ofthe results of these studies has been complicated by the possible influence of a temperature-dependent redistribution of plant growth regulators, especially gibberellin ( 17,28), and the sensitivity of starch synthesis per se to higher temperatures has remained unknown. Thus, the present work was carried out to determine the temperature optimum for starch synthesis in excised potato tuber tissue supplied with sucrose and in cellfree amyloplasts supplied with triose-P. were taken from plants grown in Reading, either in the open ground during the summer or in a glass house with supplementary heating (15-20°C) and lighting (13 h daylength) during winter. Developing corms of cocoyam (Colocasia esculenta L. Schott) were taken from plants grown under natural lighting in a heated glasshouse. Tubers and corms were washed, surface sterilized, and peeled before use. In the glasshouses, plants were grown in potting compost contained in I0-L polythene tubs and watered daily. MATERIALS AND METHODSPreparation of Discs and Measurement of Sucrose Uptake into Different Fractions. Potato tubers or cocoyam corms were sliced to 1 mm thickness,...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Temperature on Starch Synthesis in Potato Tuber Tissue and in Amyloplasts

Mohabir¹,

John²

1988

Plant Physiol.

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“…Systematic investigations have shown the influence of genetic and metabolic factors in the construction of the layers. In fact, it is probable that both an endogenous rhythm and fluctuating environmental factors contribute, their respective importance being species-specific (May & Buttrose, 1959;Buttrose, 1962;Frey-Wyssling & Muhlethaler, 1965;Jenner, 1982). The morphogenesis of helicoidal walls provides an exceptional example, the importance of which is twofold: it is an oscillatory and subcellular example, and the movement of the constituent subunits mimics the movement of the hands of a clock, characteristics which may justify a comparison with horologic systems.…”

Section: In Levels Oe Timekeeping Structuresmentioning

confidence: 99%

The Helicoidal Cell Wall as a Time Register*

Vian

Roland

1987

New Phytologist

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Summary Helicoidal cell walls are characterized by an oscillatory shift in the arrangement of cellulose microfibrils somewhat reminiscent of the rotating movement of the hands of a clock. The periodic movement can be sustained or perturbed. Thus, the helicoidal cell wall presents a temporal reading. Sensitive to temporal signals, the cell wall keeps a record of cellular events and registers very small variations, storing data at a subcellular level. The present paper emphasizes some aspects of the helicoidal cell wall relevant to timekeeping, revealing its dynamics and flexibility and leading to the question of the mechanisms of its construction.

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“…Studies using light and electron microscopy have provided detailed descriptions of the morphological and anatomical changes that characterize embryonic development (Maheshwari, 1950;Wardlaw, 1955;Natesh and Rau, 1984;Raghavan, 1986). Cellular differentiation has been studied largely in relationship to the biosynthesis and accumulation of storage proteins, lipids, and starch, macromolecular reserves that ultimately serve as nutrients for postgerminative seedlings (Jenner, 1982;Slack and Browse, 1984;Casey et al, 1986;Shotwell and Larkins, 1989). The focus of attention on these reserves reflects their agricultura1 importance and the fact that the abundance of these macromolecules facilitates studies of their accumulation.…”

Section: Introductionmentioning

confidence: 99%