Sucrose Storage Research Articles

Effect of hydrogen ion concentration on sucrose leakage from corn scutellum slices: Evidence for two kinds of sucrose pool within the slice

Abstract Incubation of corn scutellum slices in HCl concentrations above 0·01 M caused a marked disruption of cell function as evidenced by the copious leakage of sucrose from the tissue, the loss of the tissue's capacity for the synthesis and storage of sucrose from exogenously supplied hexose and the failure of the tissue to store exogenously supplied sucrose. In contrast, treatment of the tissue in 0·01 M HCl both in the presence and the absence of fructose increased the leakage of sucrose without seriously impairing sucrose synthesis. In addition, pretreatment of the slices in 0·01 M HCl did not reduce sucrose synthesis and storage in the presence of exogenous fructose or inhibit the storage of exogenous sucrose. The leakage of sucrose into 0·01 M HCl or 0·01 M HCl plus fructose is not ascribed to a disruption of the plasmalemma but rather to the existence of two pools of stored sucrose within the tissue, one mobile in acid and the other immobile in acid. The location of these pools within the tissue and the movements of sucrose between pools and bathing solution are discussed in relation to previously conceived ideas of cellular compartmentation and observed anatomical features of the scutellum tissue.

The effect of uranyl nitrate on sucrose production and storage in corn scutellum slices

Uranyl nitrate (1·5 × 10 −3 M) completely inhibited the storage of exogenous sucrose in slices of the corn scutellum, but had no effect on the storage of intracellularly synthesized sucrose. Sucrose production from glucose or fructose was inhibited by 15 and 35 per cent, respectively, and the inhibitions were not increased by a 10-fold greater uranyl ion concentration. Essentially the same degrees of inhibition were obtained when the slices were incubated with uranyl ion and sugar as when the slices were pretreated in uranyl ion and then washed and placed in sugar solutions. In the latter case, the inhibition was shown to be completely reversed by hydrogen ion or partially reversed by certain metal cations. Uranyl ion also strongly inhibited the exchange of sucrose between the bathing solution and the storage compartment of the cell. These results are consistent with a scheme which includes two sucrose transport membranes, one at the cell exterior for exogenous sucrose and the other at the cell interior between the sucrose synthesis and storage compartments and a membrane containing hydrophilic pores through which hexose molecules can freely diffuse from the cell exterior into the synthesis compartment.

Título en español.

Título en español.

Growth, Composition, and Metabolic Responses of Sugar Beet to Preharvest Application of Maleic Hydrazide1

AbstractMaleic hydrazide, 8 × M−3, was applied to the foliage of mature plants of sugar beet (Beta vulgaris L.). Its effects on growth and various aspects of composition and metabolism were determined 7, 14, and 21 days after treatment. The striking result was a significant curtailment of growth of leaves and an increase in sucrose content of the storage root. Maximum inhibition of leaf growth, 66%, was evident 7 days after treatment. The sucrose content of the roots was significantly larger on all three days of measurement, while protein and total N were considerably less. Higher nitrate and lower nitrite contents paralleled a decrease in the activity of nitrate reductase.Respiration in both leaves and roots was depressed, but the photosynthetic rate was greater by 49%, 21 days after treatment. The activity of nitrate reductase and transaminase in leaf and root fell 40% and 18% below values in control plants by the 21st day following treatment. Invertase activity was significantly reduced. The activities of glucose‐1‐, glucosed‐, and fructose‐6‐phosphatases; phenyl phosphatase; and ATPase were depressed by treatment. On the other hand, the activities of the enzymes of sucrose biosynthesis, UDPG‐pyrophosphorylase, sucrose synthetase, and sucrose phosphate synthetase, were significantly stimulated.The responses suggest that “ripening” may be induced and that the late autumn growth, which often occurs at the expense of stored sucrose, may be considerably reduced by the foliar application of maleic hydrazide 7 to 21 days before the sugar beets are to be dug.

Differential Physiological Response of Sugarcane Varieties to Osmotic Pressures of Saline Media1

Exposure of sugarcane varieties to different levels of osmotic pressure in nutrient solution (by adding NaC1) emphasizes varietal differences in response to this pressure. Working with varieties H 37‐1933 (known to be sensitive to drought) and H 49‐3533 (known to be tolerant to drought), physiological responses to added amounts of osmotic pressure were measured. Differential responses between these two varieties were shown in growth, flowering (tasseling), formation of joints, uptake of phosphorus, uptake of sodium, and storage of sucrose. These experiments showed that, above a certain pressure, there is a withdrawal of sugars from the basal or older joints. Provided that they have not been exposed to osmotic pressure great enough to cause death, after removal of the added pressure the plants start returning sugar to those joints from which it was withdrawn during the period of osmotic stress.

The effect of d-mannose on sucrose storage in the corn scutellum: Evidence for two sucrose transpsort mechanisms

Evidence is presented that tissue slices of the corn scutellum contain two distinct mechanisms for the storage of sucrose. The first mechanism is responsible for the storage of exogenously supplied sucrose and is strongly inhibited by the presence of d-mannose in the sucrose-containing bathing medium. The second mechanism is responsible for the transport of sucrose (newly synthesized from hexose) from the synthesis compartment of the cell into storage. This mechanism is not inhibited by mannose. Although the intercompartmental storage of newly synthesized sucrose is unaffected by the presence of mannose, the synthesis of the disaccharide from exogenously supplied fructose is strongly inhibited when mannose is present in the bathing medium. In addition, treatment of tissue slices with mannose resulted in a drastic reduction in the ATP level of the tissue. This reduction in ATP was not accompanied by an equivalent increase in ADP or AMP. It is suggested that the effect of mannose in inhibiting the storage of exogenous sucrose and in inhibiting the synthesis of sucrose from exogenous fructose arises from ATP deficiency. This deficiency is presumably the result of mannose and mannose-6-phosphate inhibitions of glycolysis at the level of hexokinase and phosphoglucose isomerase, respectively, and/or the trapping of inorganic phosphate in a pool of non-metabolizable mannose-6-phosphate. Possible mechanisms for sucrose storage are discussed.

The effect of tris(hydroxymethyl)aminomethane on sucrose storage in and leakage from corn scutellum slices

Sucrose leaked from slices of the corn scutellum incubated in tris(hydroxymethyl)aminomethane (tris) buffer (0·06 M, pH 7·5). When the slices were incubated in tris buffer plus fructose the amount of sucrose leakage was increased. The sucrose content of slices incubated in tris buffer plus sucrose declined nearly as much as those incubated only in tris indicating that tris almost completely inhibited the storage of exogenous sucrose. Evidence is presented that these results were due to the action of tris on the membrane separating the storage compartment of the scutellum cell from the cell exterior rather than on the membrane between the sucrose synthesis compartment and the cell exterior. Slices pretreated in tris buffer for 1 hr and then quickly washed with water were no longer leaky, but the inhibition of exogenous sucrose storage persisted. This inhibition could be reversed by H + and either Al 3+ or certain divalent cations.

Quantitative genetics of sugarcane

1. A project has been initiated to explore the possibilities of selection for higher levels of sucrose storage in the wild species S. spontaneum, using a representative sample of parental clones under conditions of natural crossing. 2. The aim of the programme is the development of superior clones to represent the wild species in conventional breeding programmes, which involve repeated backcrossing to S. officinarum. 3. An analysis of the first generation following the intercrossing of 21 parental types without emasculation, has demonstrated extensive genetic variability within and between progeny groups for fibre, sucrose, reducing sugars and yield grade. 4. Fibre and sucrose percent fresh weight are characters of high repeatability (0.4-0.6), and show little evidence of non-additive genetic effects. Individual plant performance for these characters can therefore be taken as a satisfactory basis for selection in this material. 5. The average degree of self-fertilization occurring under conditions of natural crossing has been estimated to be 0.69±.13, based on analyses of the quantitative genetic data for fibre and sucrose percent fresh weight. 6. The within-family genetic variance observed is of the order of five times that expected if the parental clones were homozygous. Much of the genetic variability induced within-families is therefore due to self-fertilization of heterozygous parental material, though the exact proportion cannot be deduced from the present data. 7. The initial response to selection for increased sucrose percent fresh weight is predicted to be of the order of 50% of the population mean. Comparable responses in subsequent cycles of the programme appear to be possible, provided an adequate degree of outcrossing can be achieved by controlled pollination techniques. 8. The genetic correlations between sucrose and other characters of importance are favourable to the objectives of the breeder, or else of a low order. There is no general relationship between the somatic chromosome number of the parental clones and the mean sucrose level of their progeny.

Electron microscope studies of glutamic oxalacetic transaminase in rat liver cell.

Liver tissue of the rat, fixed in glutaraldehyde and formaldehyde, was incubated in a medium which consisted of 20 mML-aspartic acid, 2 mM alpha-ketoglutaric acid, 50 mM imidazole and 6 mM lead nitrate at pH 7.2-7.4. The electron-opaque precipitates, due to glutamic oxalacetic transaminase activity in liver cells, were found to be localized to the cristae and surface membranes of the mitochondria, the limiting membrane of the microbodies, and the nuclear membrane. Sucrose storage and trauma resulted in altered morphology and diminished final product intensity in mitochondria, but the microbody enzyme activity disappeared completely under these conditions. These distinctive responses of enzymatic activity are considered to indicate a difference in either the enzyme protein or its membrane attachment to these two sites. The use of a buffered dehydrating ethanol series to prepare tissue blocks for electron microscopy appeared to result in more precise intracellular localization of enzymatic reaction product.

Aerobic fermentation and phosphofructokinase in tissue slices of the corn scutellum

The study of gas exchange in tissue slices of corn scutellum incubated either in water or 0·1 M fructose showed that the presence of the hexose increased the rate of glycolysis in this tissue 4- to 7-fold depending on the experimental conditions, and that this increase was quantitatively linked with an aerobic alcoholic fermentation. The properties of crude phosphofructokinase (PFK) were studied and compared with the properties of PFK's from other higher plants, one of which does not carry out aerobic fermentation in the presence of exogenous hexose. Corn scutellum PFK appears to be similar in its properties to the PFK's of other higher plants. The tissue levels of certain metabolic intermediates, some of which influence PFK activity (citrate, ATP, inorganic orthophosphate, and fructose-1,6-diphosphate), were determined and were found not to vary in amount under regimes of low and high glycolytic activity. No evidence was found to support a regulatory role for PFK on the rate of glycolysis in corn scutellum slices. Alternative mechanisms for the control of glycolysis in scutellum slices are proposed. These controls may involve the reactions leading to the metabolic utilization of stored sucrose and the intracellular distribution of adenine nucleotides and inorganic phosphate.

Título en español.

Se aplicaron combinaciones diferentes de ácido giberélico (AG) y de silicio (Si) a hojas de caña de azúcar de 12 semanas de edad sembrada en arena. Las concentraciones de AG eran equivalentes a soluciones del ácido puro al 0, 0.01 y 0.10 por ciento, y las de Si eran 0, 100, 1,000 y 10,000 partes por millón de Si elemental. El diseño utilizado fue un factorial de 3 x 4, con cuatro replicaciones. Fueron cuatro los objetivos: 1, Comprobar nuevamente la habilidad para estimular la formación de sacarosa, tanto del AG como del Si; 2, determinar si las hojas podían absorber el Si necesario para producir este estímulo en la producción de la sacarosa; 3, determinar si el AG y el Si pueden realizar estas funciones cuando se combinan en una sola aplicación; y 4, evaluar los efectos de una combinación del AG y del Si sobre el crecimiento y las enzimas. Se cosechó sólo una vez para hacer el análisis de la hoja y del tejido reservante tierno, 5 semanas después del tratamiento. Se obtuvieron los resultados siguientes: 1. Datos obtenidos del peso húmedo señalaron que las 10,000 p.p.m. del Si retrasaron grandemente el crecimiento. La aplicación de AG aumentó el crecimiento de los entrenudos y también moderadamente el peso húmedo en la concentración intermedia. Los efectos tóxicos del Si disminuyeron en parte con la concentración intermedia del AG. 2. Como efectos principales, se observaron aumentos en el contenido de sacarosa de la hoja y del tejido reservante tierno, tanto por el AG como por el Si. El contenido más alto de sacarosa se obtuvo mediante la aplicación de una combinación de AG al 0.01 por ciento y 100 p.p.m. de Si. 3. Los aumentos en la sacarosa fueron el resultado parcial de haberse estimulado la producción de cuetosas totales. La fructosa en la hoja disminuyó con los tratamientos altos del AG y del Si. 4. El comportamiento de las enzimas verificó las observaciones anteriores. La alta concentración de Si disminuyó la actividad de la fosfatasa, la ATP-asa, la peroxidasa y la oxidasa de polifenol. Sin embargo, parece que los aumentos en la sacarosa se deben, casi totalmente, a la supresión de la invertasa por el Si y el AG. 5. Los resultados comprueban que el AG y el Si pueden aumentar la producción y las reservas de sacarosa independientemente uno del otro, y que cuando se combinan pueden aumentar la sacarosa hasta niveles inalcanzables por cualquiera de los dos factores independientemente. Sólo son necesarias cantidades relativamente pequeñas de ambos constituyentes, las cuales pueden combinarse fácilmente en una sola aplicación foliar.

The storage of exogenous sucrose by corn scutellum slices

Corn scutellum slices stored sucrose when incubated in either sucrose or fructose, and similar maximum rates of net storage were obtained with 0·4 M sucrose or 0·2 M fructose. It is concluded that exogenous sucrose is stored without prior inversion. This conclusion is based on the following: (1) The amount of extracellular inversion (as measured by the appearance of glucose and fructose in a 0·3 M sucrose bathing solution) was too low to support a net sucrose synthesis and storage, and (2) sucrose storage in slices bathed in optimal concentrations of fructose or glucose was increased by the addition of sucrose to the bathing medium. Further evidence for the existence of a transport system for exogenous sucrose was obtained in the demonstration of an exchange of sucrose between the bathing solution and the storage compartment. The rate of exchange was increased as the concentration of exogenous sucrose was increased, was doubled in the presence of citrate-phosphate buffer, was little affected by pH in the range 5·0–7·3 and showed no dependence on the net amount of sucrose stored.

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

Low moisture supply, controlled by 3 methods (adding NaCl to a complete nutrient solution, allowing a cut stalk to wilt, or withholding irrigation in the field), decreased the velocity and percentage rate of translocation of (14)C-photosynthate. The surplus sucrose not used in growth moved more slowly in the phloem and was stored in the stalk.Low moisture supply depressed translocation of (14)C-photosynthate more severely than it curtailed formation of (14)C-photosynthate in the same leaf: therefore, the effect of moisture supply upon translocation was primary.Low moisture supply retarded profile development in the stem, and a loss in moisture gradient was associated with a steepened slope of the profile. These results indicate a flow mechanism of translocation rather than diffusion.Results reported now and previously point to the operation of a slow pressure-flow mechanism particularly during the night but also during the day; superimposed upon this general mass transport is the more rapid process of phototranslocation which is independent of sugar gradients and which can cause the accumulation of sucrose at the storage-sink.During ripening, storage of sucrose in the stalk may be increased by withholding water because less sucrose is hydrolyzed in transit, less is used in growth, and the slowly moving sucrose has more time for transfer from the phloem to the storage parenchyma.

Leakage and storage of sucrose during sucrose synthesis in the corn scutellum

During incubation of corn scutellum slices in fructose solutions (0·1–0·9 M) sucrose leaked ( leakage A) from the slices, and additional leakage ( leakage B) occurred upon dilution of the fructose solution to 0·1 M or less. Sucrose was also stored within the slices, and net sucrose synthesis (stored plus leaked) was 20–25 μmoles/hrg fresh wt. Fructose concentration of the bathing solution had little effect on net sucrose synthesis or on the amount of sucrose leakage A. However, with increased fructose concentration, the amount of sucrose stored decreased while the amount of sucrose leakage B increased. The rate of sucrose leakage B was strongly inhibited by fructose, galactose, polyhydric alcohols and 2,4-dinitrophenol. After incubation of the slices in 14C-fructose, leakage A and leakage B sucrose were found to be quite different with respect to specific activity and distribution of 14C between the fructose and glucose moieties. From these results and the results of inhibition studies, it is concluded that the two types of leakage have different origins within the cell.

Regulation of Acid Invertase-levels in Sugar Cane Stalks by Auxin- and Metabolite-mediated Control Systems

IMMATURE storage parenchyma cells of sugar-cane stalks contain an acid invertase located in the vacuoles and the outer space (cell walls). The physical properties of the enzyme at both loci appear to be identical. The enzyme is readily made soluble simply by grinding the tissue. Measurements of the rate of internode elongation and total acid invertase show that these two parameters are linearly correlated. This particular acid invertase is absent from the mature storage tissue of sugar cane, but persists in the mature tissue of two closely related species which do not store sucrose in high concentrations. However, in mature tissue of sugar cano other invertases occur but not in the vacuole1–3

The Evolutionary Significance of Sugar Accumulation in Saccharum

Sugar levels in the various species of the Saccharum complex suggest an evolutionary increase in sugar content. Under suitable ecological conditions, survival through sucker growth may be dependent on rapid mobilization of stored carbohydrate. Selection pressure for sucrose storage would then oocur if sucrose was more readily remobilized than other storage carbohydrates. It is suggested that this ecological situation occurred in New Guinea, and that natural and not human selection lead to the evolution of S. oJJicinarum.