Carbohydrate Reserves of Grasses

Smith, D. H.

doi:10.1016/b978-0-12-774750-7.50029-4

Cited by 40 publications

(17 citation statements)

References 24 publications

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“…Although the temperate grasses studied here are known to store fructans (Cugnac, 1931;Smith, 1968aSmith, , 1972, low contents (< 1 %) of starch, or at least a-l,4-linked glucose polymers, were found in some autumn and spring samples. Starch appeared in the roots from the long-term mesh bags in October and in those from soil cores in December and was still present in the spring.…”

Section: Discussionmentioning

confidence: 99%

Carbohydrates in Roots and Rhizomes of Perennial Grasses

Steen

Larsson²

1986

New Phytologist

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SUMMARYRoots and rhizomes were sampled in a three-year-old grass ley during one year using a mesh bag method and soil coring. Samples, collected after different growth periods (1, 2, 3, 4, 5, 6 and 12 months) and at different times of the year, were analyzed for carbohydrates and Klason lignin. Throughout the year the rhizomes contained more non-structural carbohydrates (20 to '^0% of the organic matter) than the roots (1 to 8%). The non-structural carbohydrate content varied over the year with a maximum in autumn and minimum in early spring and sunimer after the first grass cut. Fructan was the predominant constituent in this fraction. Structural carbohydrates and Klason lignin showed relatively small variations over the annual cycle. The ratio between structural carbohydrates and Klason lignin showed little variation with time but differed between roots (1-9) and rhizomes (2-5). The xylose content was higher in the roots than in the rhizomes. Only small changes occurred with time in the relative composition of the structural carbohydrates. This consistency in composition implies that there was a difference between subterranean and aerial parts. In the latter, ageing is characterized by increased lignification and systematic changes in structural carbohydrates owing to the formation of secondary cell walls.

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Section: Discussionmentioning

confidence: 99%

Carbohydrates in Roots and Rhizomes of Perennial Grasses

Steen

Larsson²

1986

New Phytologist

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“…Large quantities of fructan are usually stored in leaves and stems of grasses during autumn and winter. They are mobilized again during initial growth in early spring, during regrowth after mowin", and during the grain filling period (3,10,12,17). As a general rule fructan is accumulated when the conditions allow photosynthesis but are restricting growth or transport; fructans are depleted under opposite conditions.…”

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confidence: 99%

Regulation of Fructan Metabolism in Leaves of Barley (Hordeum vulgare L. cv Gerbel)

Wagner¹,

Wiemken²,

Matile³

1986

Plant Physiol.

153

106

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Excised primary leaf blades of barley (Hordeum vulgare L. cv Gerbel) rapidly synthesized large quantities of fructan in the light and, upon transfer to the dark, they rapidly degraded it again. In the course of such a light/dark cycle the activities of sucrose-sucrose-fructosyltransferase (SST), fructan hydrolase, and invertase were measured in cell-free extracts of the blades. SST activity increased 20-fold within 24 hours in the light and disappeared again upon transfer to the dark during a similar period of time. Cycloheximide inhibited the increase of SST activity in the light indicating de novo synthesis. The loss of SST activity in the dark, however, was unaffected by cycloheximide. No SST activity appeared in the light if photosynthesis was inhibited by lowering the CO2 concentration in the atmosphere. However, SST activity and fructan synthesis were induced even in the dark and at a low CO2 concentration when the leaf blades were immersed in a solution of sucrose. Several other sugars, maltose and fructose in particular, had the same effect. Trehalose induced SST activity but no fructan synthesis occurred. The activities of fructan hydrolase and invertase changed little during the light/dark cycle. It is suggested that the control of SST activity in conjunction with the supply of photosynthates plays a key role in the regulation of fructan metabolism.Fructan, a polyfructosylsucrose of varying molecular size, is the main carbohydrate reserve for intermediate and long-term storage in vegetative organs of perennial forage grasses and cereals, particularly in temperate and frigid climate zones (1,7,11,15). Whereas the diurnal difference between production, export, and consumption of photosynthates in the leaves is largely balanced by storage and mobilization of sucrose and starch (2, 16), fructan seems to be the reserve used preferentially for balancing seasonal differences due to changes in plant development and weather. Large quantities of fructan are usually stored in leaves and stems of grasses during autumn and winter. They are mobilized again during initial growth in early spring, during regrowth after mowin", and during the grain filling period (3,10,12,17). As a general rule fructan is accumulated when the conditions allow photosynthesis but are restricting growth or transport; fructans are depleted under opposite conditions.Fructan can be produced in enormous amounts which may exceed 70% of the dry weight of the leaves (13,18). Fructan and the fructan metabolizing enzymes were found to be located in the vacuoles of barley mesophyll cells (18,19). The same localization was found in the cells of the storage parenchyma of the tubers of Jerusalem artichokes (5).In spite of the central role of fructan metabolism in carbon partitioning in economically important grasses such as wheat and barley, very little work has been done on the enzymology and regulation of fructan synthesis and degradation (8,11,15). With the excised cereal leaf blades we had a system at hand in which fructan synthesis coul...

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“…Fructan constitutes the major non-structural carbohydrate in temperate perennial grasses (Meier & Reid, 1982) and is mainly accumulated in the lower stem base (Smith, 1972) where it can account for as much as 35 % of the dry weight (Volenec, 1986). In addition to its dominant role as reserve carbohydrate, it has been suggested that fructan may have an osmoregulatory function and influence the cold hardiness of fructan-accumulating species in cool regions (Suzuki & Nass, 1988).…”

Section: Introductionmentioning

confidence: 99%

Fructan and cryoprotection in ryegrass (Lolium perenne L.)

Gonzalez¹,

Boucaud

Salette³

et al. 1990

New Phytologist

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SUMMARYChanges in carbohydrate content and composition of ryegrass {Lolium perenne L.) cv. Reveille field-grown in Normandy were investigated from May 1987 to May 1988. During the winter period, the concentrations of high DP (degree of polymerization) fructan were the lowest whilst those of ethanol-soluble carbohydrates were the highest. Ethanol-soluble carbohydrates also accounted for most of the non-structural carbohydrates of four cultivars oi Lolium perenne field-grown in central France in January 1989. The accumulation of osmotically active carbohydrates during winter leads only to a small depression of freezing point and consequently, these sugars cannot be considered as efficient cryoprotectants in ryegrass.

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Carbohydrate Reserves of Grasses

Cited by 40 publications

References 24 publications

Carbohydrates in Roots and Rhizomes of Perennial Grasses

Carbohydrates in Roots and Rhizomes of Perennial Grasses

Regulation of Fructan Metabolism in Leaves of Barley (Hordeum vulgare L. cv Gerbel)

Fructan and cryoprotection in ryegrass (Lolium perenne L.)

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