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Biosynthesis of Sucrose and Sucrose-Phosphate by Sugar Beet Leaf Extracts

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... Sucrose content was measured using the resorcinol method [38]. Approximately 1 g of leaf tissue was homogenized in a mortar with 3 mL of water. ...
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The efficacy of plant-based biostimulants lays on the extraction of bioactive compounds that can trigger positive biological responses in plants. Their use has been increasing for lowering the production costs, enhance the yield and the stress tolerance, and improve the cropping systems’ sustainability. The aim of this work was to investigate the effect of maceration time on borage extracts, subsequently sprayed on rocket plants hydroponically grown. A preliminary test was also assessed to evaluate the extracts’ effect on seeds germination. Borage leaves and flowers were separated and macerated in the same conditions for different times. The obtained borage extracts were applied two times during the cultivation of rocket plants. The yield was not affected by the treatments, while the quality of leafy vegetables was improved. The results indicated that the flower extracts (FE) were more active than leaf extracts (LE) in stimulating the crop response. Promising results were observed on the nitrate assimilation, with reduced accumulation in the edible and commercial parts. Non-destructive analysis revealed that electron transport rates were significantly higher in treated plants. Biostimulant effects were also confirmed by the lowering of sucrose and sugars content in the treated plants and by a general increment of secondary metabolites.
... The resorcinol solution was prepared by adding 35 mg of resorcinol and 90 mg of thiourea in 250 mL HCl 30%, mixed with 25 mL of acetic acid and 10 mL of distilled water. Samples were cooled at room temperature and spectrophotometer readings were performed at 500 nm (Rorem et al. 1960). A calibration curve was built with sucrose standards at 0, 0.5, 1, 1.5, and 2 mM. ...
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Microgreens are gaining interest for claimed high nutraceutical properties, but data on their chemical composition are so far limited. Although often grown hydroponically, their mineral requirements are still unknown. This study aimed to provide an insight into yield, mineral uptake, and quality of basil, Swiss chard, and rocket microgreens grown in a hydroponic system. With reference to data reported in literature for the same species hydroponically grown but harvested at adult stage, these microgreens yielded about half, with lower dry matter percentage, but higher shoot/root ratio. They showed high concentrations of some minerals, but their nutrient uptake was limited due to low yield. Nitrates content was lower if compared with that usually measured in baby leaf or adult vegetables of the same species, as well as the concentration of chlorophylls, carotenoids, phenols, and sugars. Therefore, microgreens seem to be interesting and innovative low-nitrate-salad crops requiring low fertiliser inputs. Nevertheless, an improvement in yield as well as in the content of nutraceutical compounds would be desirable.
... The resorcinol solution was prepared by adding 35 mg of resorcinol and 90 mg of thiourea in 250 mL HCl 30%, mixed with 25 mL of acetic acid and 10 mL of distilled water. Samples were cooled at room temperature for 15 min and spectrophotometer readings were performed at 500 nm [27]. A calibration curve was built with sucrose standards at 0, 0.5, 1, 1.5, and 2 mM. ...
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The microgreens are innovative products in the horticultural sector. They are appreciated by consumers thanks to their novelty and health-related benefits, having a high antioxidant concentration. This produce can be adopted for indoor production using hydroponic systems. The aim of the present work was to investigate the influence of three growing media (vermiculite, coconut fiber, and jute fabric) on yield and quality parameters of two basil varieties (Green basil—Ocimum basilicum L., Red basil—Ocimum basilicum var. Purpurecsens) and rocket (Eruca sativa Mill.) as microgreens. Microgreens were grown in floating, in a Micro Experimental Growing (MEG®) system equipped with LED lamps, with modulation of both energy and spectra of the light supplied to plants. Results showed high yield, comprised from 2 to 3 kg m−2. Nutritional quality varied among species and higher antioxidant compounds were found in red basil on vermiculite and jute. Coconut fiber allowed the differentiation of crop performance in terms of sucrose and above all nitrate. In particular, our results point out that the choice of the substrate significantly affected the yield, the dry matter percentage and the nitrate concentration of microgreens, while the other qualitative parameters were most influenced by the species.
... The sucrose assay was performed by mixing 0.2 mL of crude extract with 0.2 mL of 2 M NaOH and incubating in a water bath at 100°C for 10 min, then 1.5 mL hot resorcinol buffer (containing 30% hydrochloric acid, 1.2 mM resorcinol, 4.1 mM thiourea 1.5 M acetic acid) was added to samples and they were incubated in a water bath at 80°C for another 10 min. After cooling at room temperature, the optical density was determined spectrophotometrically at 500 nm, using a sucrose standard curve (0, 0.5, 1, 1.5 and 2 mM) (Rorem, Walker, & McCready, 1960). ...
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Corchorus olitorius is mainly cultivated in Africa and is used in the human diet for its nutraceutical proprieties. In this work, C. olitorius was grown in a floating system using a standard (NS100%) or halved (NS50%) nutrient solution. Yield was evaluated at harvest when plants reached the baby leaf stage. Quality of leaves was estimated by measuring sugars, nitrate, chlorophylls, carotenoids, polyphenols, and anthocyanins. Yield was similar to other common leafy vegetables cultivated in floating systems. Analytical determinations showed good levels of antioxidant compounds and sugars. Mineral contents were relevant for Ca, Mg and Fe in comparison with C. olitorius cultivated in soil and other common leafy vegetables. Results showed these plants had healthy characteristics for human nutrition, in particular for women and children. C. olitorius had a good performance in the floating system with yield ranging from 0.8 to 2.4 kg m−2. Mineral nutrient levels were higher than in the major leafy vegetables. Nutrient solutions influenced anthocyanin accumulation (+37% in NS50% in spring and +48% in NS50% in summer). Leaf nitrate content was –50% in NS50% at spring cultivation. The overall quality parameters suggest that C. olitorius can be an optimal candidate for baby leaf production in the fresh cut leafy vegetable industry.
... Afterward, as a result of hexokinase, glucose is converted into glucose-6-phosphate (G6P); then, the enzyme hexose phosphate isomerase transforms G6P into fructose-6-phosphate (F6P) (3). Finally, F6P loses the phosphate molecule and releases fructose (4)(5)(6). Glucose and fructose are the most important hexoses as the energy source for the plant (3). These, along with other less abundant sugars, are found in plants in a dynamic state, since the energy they contain is required in many cell reactions, including protein and lipid syntheses, among others (7). ...
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Fructans are the reserve carbohydrates in Agave spp. plants. In mezcal factories, fructans undergoes thermal hydrolysis to release fructose and glucose, which are the basis to produce this spirit. Carbohydrate content determines the yield of the final product, which depends on plant organ, ripeness stage, and thermal hydrolysis. Thus, a qualitative and quantitative characterization of nonstructural carbohydrates was conducted in raw and hydrolyzed juices extracted from Agave salmiana stems and leaves under three ripeness stages. By high-performance liquid chromatography (HPLC), fructose, glucose, sucrose, xylose, and maltose were identified in agave juice. Only the plant fraction with hydrolysis interaction was found to be significant in the glucose concentration plant. Interactions of the fraction with hydrolysis and ripeness with hydrolysis were statistically significant in fructose concentration. Fructose concentration rose considerably with hydrolysis, but only in juice extracted from ripe agave stems (early mature and castrated). This increase was statistically significant only with acid hydrolysis.
... The sucrose assay was performed by mixing 0.2 mL of crude extract with 0.2 mL of 2 M NaOH and incubated in a water bath at 100°C for 10 min., then 1.5 mL of hot resorcinol buffer (containing 30% hydrochloric acid, 1.2 mM resorcinol, 4.1 mM thiourea 1.5 M acetic acid) was added to the samples and incubated in a water bath at 80°C for another 10 min. After cooling to room temperature, the optical density was determined spectrophotometrically at 500 nm, using a sucrose standard curve (0, 0.5, 1, 1.5 and 2 mM) (Rorem et al., 1960). The analysis of reducing sugars was performed by using 0.2 mL of crude extract that was added to 0.2 mL of a solution containing 62.6 mM dinitrosalicylic acid (DNS) and 1.52 M potassium sodium tartrate. ...
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Corchorus olitorius (L.) is one of the main crops for fibre production, cultivated in tropical and subtropical environments, from Africa to Japan, across the Middle East and India. In developing countries, the leaves are used as a medicine and also as food. In this study, we evaluated the physiological responses of nine accessions of C. olitorius in order to nominate the most suitable one for introduction into southern Europe. African and Asian accessions obtained from the Leibniz Institute IPK gene bank were analysed for their photosynthetic variables and quality traits during cultivation. Accessions from Africa, in particular those from Egypt and Libya, showed higher intrinsic water-use efficiency. However, at high temperatures, the Japanese accession also showed a high level of water-use efficiency, as evidenced by the high carbon fixation rate. Chinese and Indian accessions showed a reduction in growth performance, although a high concentration of antioxidants in the leaves and biomass accumulation have been reported in those accessions. C. olitorius demonstrated an intrinsic attitude to adaptation; according to their subtropical origin, all of the plants grew at sub-optimal status (Fv/Fm). These data, however, do not seem to compromise the potential of these plants as a crop for growing in southern Europe. Moreover, their introduction can be based solely on their biochemical quality traits.
... The resorcinol solution was prepared by adding 35 mg of resorcinol and 90 mg of thiourea in 250 mL HCl 30%, mixed with 25 mL of acetic acid and 10 mL of distilled water. Samples were cooled at RT and spectrophotometer readings were performed at 500 nm (Rorem et al., 1960). Sucrose levels were calculated referring to a sucrose calibration curve [0, 0.5, 1, 1.5, and 2 mM] with a R 2 value of 0.9977. ...
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The aim of the work was to test the efficacy of the antitranspirant Scudotherm® in preventing cold damages on Phaseolus vulgaris L. Two tests were conducted: the first between June-July 2018, and the second between May-June 2019. Plants were grown in a greenhouse, in plastic pots (10 pots/treatment), on a peaty substrate. Treatments were carried out on three-week-old plants, by foliar application 24 hours before the stress. The experimental design included treatments with Scudotherm® at 2% compared to an untreated and unstressed control, and to an untreated but stressed control (con-trols were sprayed with tap water). The cold stress was induced by placing the plants at 3-4 °C, for 48 hours. Both in vivo and destructive analyzes were performed to evaluate the health status of plants, immediately after stress and after a one-week recovery period. The analyzes were performed on three biological replications. No significant effect of the treatments was observed on chlorophylls in vivo, chlorophyll a fluorescence parameters, secondary metabolites (anthocyanins and phenolic index), and lipid peroxidation. Significant variations were found in the metabolism of the sugars. Scudotherm® allowed maintaining the sucrose concentration similar to control and lower than stressed plants. During the first year, a similar behavior was also recorded for total sugars. These results suggested that Scudotherm® is able to mitigate some of the negative consequences of low temperatures, acting as a physical barrier on leaves, with an indirect physiological and biochemical effect.
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The effect of lowering oxygen concentration on the expression of nodulin genes in soybean callus tissue devoid of the microsymbiont has been examined. Poly(A)+ RNA was isolated from tissue cultivated in 4% oxygen and in normal atmosphere. Quantitative mRNA hybridization experiments using nodule-specific uricase (Nodulin-35) and sucrose synthase (Nodulin-100) cDNA probes confirmed that the synthesis of the uricase and sucrose synthase is controlled by oxygen at the mRNA level. The steady-state levels of uricase and sucrose synthase mRNA increased significantly (5–6- and 4-fold respectively) when the callus tissue was incubated at reduced oxygen concentration. Concomitant with the increase in mRNA level a 6-fold increase in specific activity of sucrose synthase was observed. Two messengers representing poly-ubiquitin precursors also responded to lowering the oxygen concentration. The increase was about 5-fold at 4% oxygen. No expression at atmospheric oxygen or in response to low oxygen was observed when using cDNA probes for other nodulin genes such as leghemoglobin c3, nodulin-22 and nodulin-44.
IntroductionFormation of MonosaccharidesGlycosyl Transfer from Sugar NucleotidesSummary
Article
This chapter discusses the enzymic synthesis of numerous glycosides, including oligosaccharides and polysaccharides, which is subsequently effected by the transfer of a glycosyl residue from a saccharide donor to an appropriate acceptor. Transglycosylations involve only a redistribution of glycosidic linkages among saccharides, not a net increase in the number of such linkages. Another mechanism for the enzymic synthesis of saccharides is one that occurs through the transfer of the glycosyl group from a glycosyl phosphate to an appropriate acceptor. The evidence for the participation of glycosyl nucleotides in the biosynthesis of numerous glycosides, including disaccharides and polysaccharides, are described in the chapter.
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As measured 7, 14, and 21 days after the application of 10(-2) M vanadyl sulfate solution to the foliage of 4.5-month-old sugar beet plants, significantly less growth of the leaves and an increase in the sucrose content of the storage root resulted. Accompanying these alterations were a higher rate of carbon dioxide fixation, a lower rate of respiration, and a decreased rate of nitrate reductase, glutamic-pyruvic transaminase, phosphatase, and invertase activity. The enzymes of sucrose synthesis, sucrose synthetase, sucrose phosphate synthetase and uridine diphosphate glucose-pyrophosphorylase were stimulated. The content of reducing sugar, nitrite N, amino acids and protein was less, and that of nitrate N was greater in the vanadium-treated plants. In the majority of cases the greatest magnitude of change occurred during the first 7 days following treatment. The changes in growth and chemical composition are believed to be closely related to the stimulation or inhibition of the various enzymes by vanadyl sulfate.
Article
Sucrose and sucrose 6-phosphate synthetase were isolated from potato tubers, partially purified and their properties studied. The sucrose synthetase showed optimum activity at 45 degrees and was inhibited competitively by ADP and some phenolic glucosides. The Ki's for these inhibitors were determined. Mg(2+) was found to activate this enzyme. Activity toward UDP-glucose or ADP-glucose formation was measured. The optimum conditions for sucrose and UDP-glucose formation were found to differ. The specificity for the glucosyl donor and acceptor were determined.The optimum conditions for sucrose 6-phosphate synthetase activity were studied. This enzyme was not inhibited by either ADP or phenolic glucosides; UDP-glucose was the only glucosyl donor for sucrose 6-phosphate formation.
Article
In organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (Spinacia oleracea). Immunoblot analysis using a specific antiserum against the mitochondrial adenylate (ADP/ATP) translocator of Neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (Acer pseudoplatanus). The double silicone oil layer-filtering centrifugation technique was employed to study the kinetic properties of adenylate transport in the purified chloroplasts; ATP, ADP, AMP, and most importantly ADP-Glc were shown to be recognized by the adenylate translocator. Similar to the situation with sycamore amyloplasts, only ATP and ADP-Glc uptake was inhibited by carboxyatractyloside, an inhibitor of the mitochondrial adenylate translocator. Evidence is presented to show that the ADP-Glc transported into the chloroplast stroma is utilized for starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-d-glucan 4-alpha-d-glucosyltransferase). The high activity of sucrose synthase producing ADP-Glc observed in the extrachloroplastic fractions suggests that starch biosynthesis in chloroplasts may be coupled with the direct import of ADP-Glc from the cytosol.
Article
Waterlogging is predicted to increase in both magnitude and frequency along with global warming, and will become one of the most severe adversities for crop production in many regions. Nitrogen is considered to be an effective up-regulatory nutrient for crops grown under stress and non-stress conditions. In this study, we try to evaluate N fertiliser effects on contents of carbohydrate and N dynamics, dry matter accumulation in shoot, yield under post-anthesis waterlogging. Waterlogging after anthesis significantly reduced grain yield due to decrease in thousand-kernel-weight and in grain number per spike. High N fertiliser application aggravated grain yield loss due to post-anthesis waterlogging. These yield losses were related to the decreases in dry matter accumulation, redistribution of stored photosynthate to the grain, and the conversion capacity from carbohydrate to starch in grain. The decrease in dry matter accumulation could be attributed to the reduced activities of Pn (photosynthesis) and SPS (sucrose phosphate synthase) in the flag leaf, while the low capacity in starch synthesis could be explained by the reduced activities of sucrose synthase (SS) and soluble starch synthase (SSS) in grain. Total N uptake in shoot was also reduced, which could contribute to the losses in biomass and yield by waterlogging. The decrease in Pn was inconsistent with the increase in N content in the flag leaf at high N fertiliser application under post-anthesis waterlogging.
Article
Sucrose synthetase (UDP glucose: d-fructose 2-glucosyltransferase E.C 2.4.1.13) is inhibited during extraction from elongating internodes of sugar cane by oxidation products of phenolic compounds. p-Benzoquinone and p-chloromercuribenzoate inhibit the enzyme; the inhibition is reversed by thiol compounds. It is suggested that the inhibition of sucrose synthetase which occurs during the oxidation of phenolic compounds results from a reaction between quinones and sulphydryl groups on the enzyme. In elongating internodes, sucrose synthetase is localized in the vascular strands.
Article
Sweet sorghum (Sorghum bicolor L. Moench) stems of different cultivars (NK 405. Keller and Tracy) reveal a different pattern of sucrose accumulation with respect to in-ternodal sugar content and distribution. The onset of sucrose storage is not necessarily associated with the reproductive stage of the plant, as was hitherto assumed, but obviously occurs after cessation of internodai elongation as was postulated for the sugarcane stem. For at least two of the three cultivars, ripening is an internode to internode process beginning at the lowermost culm parts. Intensive growth of the internodes, combined with a high hexose content in stern parenchyma, shows a strong positive correlation (r |Mg 0.94) to the activity of sucrose synthase (SuSy; EC 2.4.13), but not to invertase (EC 3.2.1.26) which is not present as soluble (neutral and acid) or cell wall-bound, salt-extractable enzyme in the three culsivars investigated. Sucrose synthase measured in sucrose cleavage and synthesis direction reveals divergent activity rates and sensitivity towards exogenously applied Mg2+ ions and pH. SuSy activity is connected to the increase of internodai sucrose content in so far as (1) its decline is a prerequisite for the onset of sucrose accumulation and (2) it remains at a constant low level during sucrose storage. Sucrose phosphate synthase (SPS; EC 2.4.1.14) activity in the sorghum stem is low compared to SuSy and uniformly distributed over all inter-nodes. Only source leaves of sorghum show a considerable SPS activity, but neither stem nor leaf SPS reveal a positive correlation to the increase of internodai sucrose content. Sucrose phosphate phosphatase (SPP; EC 3.1.3.24) amounts lo only 24–30% of the respective SPS activity but follows the same distribution pattern. None of the enzymes under study proves to be responsible for the extent of sucrose storage in the stem, so other phenomena such as transport processes within the stern tissue require further investigation.
Chapter
Die folgende Darstellung ist Fortsetzung und Ergänzung des vorjährigen Berichtes (Fortschr. Bot. 25, 270); angesichts der Fülle des Materials muß jedoch auch auf einschlägige Fortschrittsberichte und Review-Artikel sowie auf einige mit größerer Ausführlichkeit abgefaßte Neuerscheinungen in Buchform verwiesen werden: Alston und Turner: Biochemical systematics (1963). Bernfeld: Biogenesis of natural compounds (1963). Goodwin: Biosynthesis of vitamins and related compounds (1963). Hegnauer: Chemotaxonomie der Pflanzen, Band II: Monocotyledoneae (1963).
Chapter
Die pflanzliche Trockensubstanz setzt sich grob gesprochen zu etwa 80 % aus den Elementen Kohlenstoff, Sauerstoff und Wasserstoff zusammen. Wie aus der Zusammenstellung der zur Bildung von 100 bushels Mais erforderlichen Mengen der einzelnen Elemente oder N?hrstoffe hervorgeht (Tab. 61), haben davon Sauerstoff und Kohlenstoff dem Gewicht nach den h?chsten Anteil.
Chapter
Brown and Morris concluded in 1893 from experiments on photosynthesis by leaves of Tropaeolum majus that sucrose was the first carbohydrate formed and that free hexoses and starch were made from it. Parkin (1912) also obtained evidence that monosaccharides were derived from sucrose and not precursors of it. However, leaves supplied exogenously with solutions of glucose or fructose synthesized sucrose (Virtanen and Nordlund, 1934) by a mechanism that was not dependent on light, but which required oxygen (McCready and Hassid, 1941; Hartt, 1943a). Plants deficient in phosphate accomplished the conversion less readily (Sisakyan, 1936; Kursanov and Kryukova, 1939; Hartt, 1943b); also, sucrose formation was inhibited by phosphatases and inhibitors of phosphate metabolism added to the sugar solutions supplied (Hartt, 1943b, c). Vittorio et al. (1954), Putman and Hassid (1954), and Porter and May (1955) supplied [14C] hexoses and concluded that free hexoses were not the direct precursors of sucrose. Calvin and Benson (1949) studied the sequence in which metabolites were formed in Chlorella during photosynthesis from NaH14CO3 and after 90 s, sucrose was radioactive in both hexose moieties but the free hexoses were unlabeled. Hexose phosphates became radioactive before sucrose. Benson and Calvin (1950) found similar results during photosynthesis by barley leaves. Following the discovery of UDPG as a cofactor in the interconversion of glucose and galactose in a yeast (Caputto et al., 1950), radioactivity was observed in UDPG before sucrose during photosynthesis (Buchanan etal., 1952). Buchanan (1953) found sucrose phosphate in sugar beet leaves and suggested that this compound arose from reaction of UDPG with fructose-1-phosphate.
Article
This chapter discusses the synthesis of uridine diphosphate (UDP)-glucose from sugar beet roots. The UDP-dependent liberation of fructose from sucrose is determined colorimetrically. Several alternative procedures for assay of the reaction in both directions are described in the chapter. The most useful procedures are spectrophotometric determination of fructose liberated from sucrose in presence of UDP; spectrophotometric measurement of UDPG and UDP; colorimetric determination of the sucrose formed after treatment by alkali or borohydride or after hydrolysis by invertase. The degree of contamination of enzyme solutions obtained from different plant material by endogenous substrates, invertase, and phosphatases, determines the method of choice to be employed. The reagents used, procedure followed, and the steps involved in the purification are also described in the chapter. The paper chromatographic procedures for nucleotides and for sugars are employed for the detection and isolation of products, particularly in analyses based on the use of radioactive substrates. Identification of components is achieved by thin layer chromatography. The maximum rate of sucrose cleavage occurs between pH 6.0 and 6.5, where the enzyme is relatively unstable.
Chapter
Only a very small number of freely occurring disaccharides are known to exist in nature. Sucrose is one of the most abundant natural products which, in addition to playing a central and vital role in plant life, is a leading commercial commodity important in human nutrition, is a substrate for bio- and chemical technology, and at times has been a critical factor shaping the destiny and history of many nations. The amount of sucrose produced in chlorophyllous plants dwarfs the quantity of other disaccharides found in nature. Trehalose, an essential metabolite in lower orders of nonphotosynthetic plants and in insects, has a wide distribution, but its overall quantity is small compared to sucrose.
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甜菜碱是细胞内重要的渗透调节物质,其积累能有效提高植物对非生物逆境的抗性。以转 betA 基因小麦和未转基因的野生型为材料,在灌浆期模拟干热风胁迫处理植株3 d,研究干热风对植株生长和籽粒产量的影响。胁迫处理后,转基因植株保持较好长势,叶片青枯失水较少,旗叶持绿面积显著大于野生型。各株系植株的光合作用能力和蔗糖磷酸合成酶(SPS)及蔗糖合成酶(SS)活性在胁迫处理后都下降,转基因植株的净光合速率下降到2.3~3.7 μmol CO 2 m -2 s -1 ,而野生型下降到1.2 μmol CO 2 m -2 s -1 ;野生型植株的SPS和SS活性的下降幅度分别为处理前56.8%和53.9%, 而转基因株系的下降幅度分别为62.3%~69.8%和56.5%~64.5%。干热风胁迫使得各株系植株的旗叶甜菜碱含量升高,但转基因株系的叶片甜菜碱含量比野生型的高18%~87%。在甜菜碱保护作用下,转基因植株在胁迫条件下能够维持较高的光合速率,合成较多的碳水化合物,使得百粒重和单株产量均高于野生型。因此,通过转 betA 基因可显著提高小麦在干热风处理条件下的甜菜碱含量从而增强其抗干热风能力。
Article
Alter young inflorescent stalks of intact, actively transpiring Yucca flaccida Haw. plants were wounded an exudate was obtained. Its flow continued for several weeks provided there was regular re-wounding. The exudate had a pH of 8.0–8.2 and contained about 18 per cent of total solids. Of these, sucrose constituted about 80–90 per cent. Glucose and fructose were minor constituents. The amino acid concentration was as high as 0.07 molar. Glutamine appeared to be the main nitrogenous constituent. The exudate only contained small amounts of inorganic solutes of which potassium was the main kation. The calcium content was relatively low. There appeared to be a great similarity between this phenomenon of bleeding and the composition of the exudate and that observed by one of the authors (P.M.L.T.) in previous years in several palm species. Various arguments are adduced in favour of the view that the exudate has a phloem origin.
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The storage at 4°C in darkness of Corchorus olitorius L. baby leaf as a ready-to-eat (RTE) vegetable has been studied for the first time. C. olitorius was cultivated in a floating system with different nutrient solutions: standard (NS100%) or halved (NS50%). Several quality factors of this produce were evaluated during season (spring, summer, autumn) considering treatments and days of storage in order to understand the interactions. During storage, sucrose, total and reducing sugars, nitrate, phenolic compounds, anthocyanins, chlorophylls, and carotenoids were measured. Results showed that chlorophylls decreased by 20–30% for both treatments and the changes were statistically different during spring. Carotenoid content did not change until the end of the storage and values ranged from 0.60 g kg⁻¹ to 0.75 g kg⁻¹ fresh weight depending on the season. Phenols and anthocyanins decreased within 10 days: −40% of phenols and −50% of anthocyanins, respectively. No interaction between nutrient solutions and storage behaviour was reported. Thus, C. olitorius resulted to be a good source of nutraceutical compounds and it is able to maintain these components during storage. Moreover, the public interest in regards to nutritional and healthy food is rapidly increasing, promoting the discovery of new vegetables, like C. olitorius, for RTE commercialisation.
Article
Sucrose phosphate synthetase (EC 2.4.1.14) is the key enzyme for sucrose synthesis in Dunaliella tertiolecta. It has been partially purified and characterized. The enzyme contains one binding site for uridine diphosphoglucose and two binding sites for fructose-6-phosphate; it is allosterically controlled by fructose-6-phosphate. Inorganic phosphate stimulates the enzymic activity, particularly in the presence of higher concentrations of fructose-6-phosphate. Sucrose phosphate synthetase is not halophilic or halotolerant. The temperature dependence of the enzymic activity cannot fully explain the observed increase in sucrose synthesis in Dunaliella by elevated temperature.
Article
A method for the complete separation of sucrose phosphate synthetase (EC 2.4.1.14) and sucrose synthetase (EC 2.4.1.13) from wheat (Triticum aestivum L.) germ is described. The separation is achieved by chromatography on DEAE-cellulose at pH 6.5. The sucrose phosphate synthetase obtained can be further purified by gel filtration. Disc electrophoresis of sucrose phosphate preparations reveals the presence of isoenzymes. Molecular weight estimates of sucrose phosphate synthetase by gel filtration and sedimentation velocity give a value of 380,000. The enzyme is inhibited by various anions, particularly citrate, maleate, and phosphate. Activity estimate should be carried out with Good's buffers in order to avoid inhibition. Nucleoside triphosphates are competitive inhibitors toward UDP-glucose. The enzyme is sensitive to sulfhydryl reagents, but activity can be restored with DTT or β-mercapto ethanol. The fact that the enzyme is inhibited by δ-gluconolactone suggests that the reaction occurs through the formation of an unstable glucose-enzyme complex. Mg(2+) can restore enzyme activity to control values when inhibited by nucleoside triphosphates, citrate, or phosphate.
Article
Effect of different enzyme effectors viz., divalent cations and plant growth regulators (PGRs) on sucrose content and sucrose metabolizing enzymes viz., sucrose phosphate synthase (SPS), sucrose synthase (SS) and soluble acid invertase (SAI) were monitored after applications of a foliar spray of magnesium (Mg) as magnesium chloride (10 mM), manganese (Mn) as manganese chloride (5 mM), GA3 (150 ppm), and ethrel (1,000 ppm)] along with water treated control. This was performed throughout cane ripening using the low sugar genotype BO 91. Foliar application of these enzyme effectors improved sucrose content and CCS %. Increase in sucrose content due to application of effectors ranged from 17.8 % (Mn) to 24.8 % (Mg) in 240 DAP, 2.59 % (GA3) to 34.5 % (Mg) in 270 DAP, 7.7 % (ethrel) to 35.1 % (Mn) in 300 DAP, 0.33 % (ethrel) to 15.8 % (Mg) in 330 DAP and 2.2 % (Mg) to 2.5 % (Mn) in 360 DAP over control, respectively; the highest increase (35.1 %) was observed with Mn treatment in 300 DAP. Quantitative activity of SAI enzyme declined, while SPS and SS increased in the apical portion of cane stalk by chemical treatments indicating their regulatory effect on sucrose metabolizing enzymes. The qRT-PCR analysis indicated differentially expression of SS and SAI gene in response to foliar application of enzyme effectors. Effect of PGR chemicals was not consistent in terms of sucrose accumulation. Reducing sugar content decreased while sucrose to reducing sugars ratio increased due to chemical treatment. Effect of the Mg and Mn treatments on sucrose content was more pronounced in the month of November and December indicating effectiveness of divalent cations in improving sucrose accumulation during the early crushing season particularly in low sucrose accumulating genotypes of sugarcane.
Article
In sugar beet plants, activities of both, sucrose synthase (SS, EC 2.4.1.13) and sucrose phosphate synthase (SPS, EC 2.4.1.14), increase with plant age, in beet tissue as well as in petioles and to a lesser extent in leaves. In beets, maximum activity of SS was 33.5 μmol/mg protein · h, and of SPS 18.1 μmol/mg protein · h. Activity of SPS is significantly higher in the core than in the peripheral parts of the beet. Cell suspensions exhibited rather low activities of SPS. The data shown for beet tissue are correlated with cell growth and sucrose concentration. Somewhat in contrast with earlier reports this indicates the significance of both enzymes in the regulation of sucrose storage: SS contributes to an increase of the sink capacity, and SPS provides the steady increase of sucrose content in the growing beet.
Article
Sugar uptake studies with isolated protoplasts from sugar beet roots indicated that glucose is transported preferentially, obviously by a H+/glucose symport mechanism. The uptake rate in conducting tissue exceeded that of storage tissue. Fructose and sucrose seemed to be transported by lower affinity. The apparent KM for fructose and sucrose was 7.8 and 18.6 mM respectively, whereas glucose uptake had a Michaelis constant of 1.4 mM. Competition experiments led to the assumption of two different carrier systems for glucose and fructose. While comparing activities of sucrose synthase (SS, E.C. 2.4.1.13), sucrose phosphate synthase (SPS, E.C. 2.4.1.14) and acid invertase (IV, E.C. 3.2.1.26) in different parts of sugar beet roots, in protoplasts and vacuoles, we obtained information on the localization and thus the possible physiological significance of these sucrose metabolizing enzymes: conducting tissue exhibits higher activities of SS, SPS and cell-wall bound acid IV than storage tissue. However, the activity of soluble acid IV was slightly higher in the latter. Concerning the subcellular compartmentation, SS seems to be restricted to the cytoplasm whereas more than 50 % of the total SPS activity is found in the vacuolar fraction. A working hypothesis for the unloading and storage of sucrose in sugar beets is proposed.
Article
The concentrations of phosphate esters, nucleotides and sugars in strawberry leaves were measured during transition from dark to light to dark again. The period in the light varied from 2 to 30 min. The rapid changes in the concentration of some of the phosphate compounds which occurred within the first few minutes were consistent with the operation of the photosynthetic carbon reduction cycle of Bassham and Calvin. A study of those intermediates which were likely to be involved in sucrose synthesis indicated that uridine diphosphate glucose and fructose-6-phosphate were the most probable precursors of sucrose.
Article
In rice plant, carbohydrates accumulated in leaf sheaths before heading are translocated to grain and affect yield formation greatly. To clarify the intrinsic mechanism of carbohydrate metabolism in the leaf sheath, we investigated the temporal and spatial variations of carbohydrate metabolism in the third leaf sheath counted from tlie top and their varietal differences. The results revealed that the amount of carbohydrate decreased from the base to the tip of the leaf sheath, irrespective of variety and developmental stage. However, the proportion of starch content in the basal one-fifth of the leaf sheath to that in the whole sheath varied from 35% to 60% with the variety. Comparing the activities of enzymes related to starch metabolism at the base, middle and tip of the leaf sheath in IR65598-112-2 (New plant type) with those in Nipponbare, the activities of ADP-glucose pyrophosphorylase, branching enzyme and granule-bound starch synthase (GBSS) showed varietal differences. Particularly, the activity of GBSS may play an important role in the varietal difference in spatial variation of starch content in the leaf sheath. In IR65598-112-2, the sucrose content in the leaf sheath was extremely high, suggesting that sucrose may be one of the carbohydrate reserves in this line.
Article
Improved conditions for extraction and assay increased rates of sucrose synthesis from uridine diphosphate glucose (UDPglucose) plus fructose 6-phosphate (F.6.P) catalysed by leaf extracts 20-fold. Rates of 17.9, 25·0, 9·2 and 27·7 μmol/hr/g fr. wt respectively were obtained from pea shoots, spinach, wheat and bean leaves. Chloroplasts isolated from pea shoots, in which half the plastids were intact, contained less than 4% of the total UDPglucose-fructosephosphate glucosyltransferase, more than 30% of the ribulose diphosphate (RuDP) carboxylase, and more than 40% of the total chlorophyll of the leaf. Although some of the UDPglucose-fructose-phosphate glucosyltransferase was associated with particles smaller than chloroplasts at least 85% of the enzyme was not precipitated at 38 000 g. UDPglucose pyrophosphorylase, also thought to be essential for sucrose synthesis, was distributed between the cell fractions in a similar manner to UDPglucose-fructosephosphate glucosyltransferase. It is concluded that sucrose synthesis in pea shoots and spinach leaves occurs mainly, in the cytoplasm.
Article
When radioactive glucose is infiltrated into apple disks, radioactive sucrose, but not free fructose, is formed. The process is inhibited by the exclusion of oxygen. Although both moieties of the sucrose molecule are labeled, most of the activity is found in the glucose portion. In addition to the sucrose labeling, some activity appears in the amino acids, notably alanine, γ-aminobutyric acid, glutamine, and asparagine.
Article
1.1. The mechanisms for biosynthesis of UDPG and sucrose in sugarbeet leaf and leaf homogenate have been investigated by providing radioactive G-1-P with various cofactors and identifying the radioactive products after short time intervals. When radioactive G-1-P is fed to an excised leaf, sucrose equally labeled in both moieties is formed. When UTP is fed with G-1-P, the yield of radioactive sucrose is reduced, and a relatively large proportion of the radioactive glucose is converted to UDPG.2.2. The leaf homogenate converts radioactive G-1-P to radioactive glucose and fructose. A mixture of radioactive G-1-P and UTP is converted to radioactive UDPG, and UDP plus ATP can replace UTP. A method for preparation and purification of radioactive UDPG is outlined.3.3. Radioactive sucrose, labeled in the glucose moiety, is biosynthesized by leaf homogenates during 15 min. incubation when radioactive G-1-P plus UTP and F-6-P are added in appropriate concentrations. There is no reaction when UTP is omitted, and fructose or F-1,6-P cannot replace F-6-P. However, UDPG does replace G-1-P plus UTP for sucrose synthesis. Traces of radioactive sucrose phosphate are found in those systems which form sucrose.4.4. These data show that sucrose is biosynthesized in the sugar-beet leaf as the product of a sequence of reactions, in which UDPG, formed from G-1-P and UTP, reacts with F-6-P to give sucrose phosphate. The sucrose phosphate is rapidly dephosphorylated, and UTP is regenerated from UDP by ATP.
Article
Radioactive sucrose, in millicurie amounts, was prepared by feeding a detached sugar beet leaf C14O2 in air for 15 to 20 minutes followed by 5 to 20 minutes additional photosynthesis in air. The low endogenous sucrose in the leaf coupled with the improved tracer yield effected by the displacement technique gave sucrose with high specific activity. This sucrose-C14, hydrolyzed by 1% invertase, was a good source for radioactive glucose and fructose. Paper chromatographic procedures were used for the isolation and purification of the sugars.
The estimation of phosphorus
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Ar.lLEN, R. J. L. 1940. The estimation of phosphorus. Biochem. Jour. 34: 858-865.
Esters phosphoriques et sucres au cours de la vegetation de la Betterave
BOUGY, E. 1956. Esters phosphoriques et sucres au cours de la vegetation de la Betterave. Compt. rend. 242: 667-669.
Synthese und anhfiufung von saccharose in der zuckerriibe
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KURSANOV, A. L. 1954. Synthese und anhfiufung von saccharose in der zuckerriibe. Botan. Zbur. S.S.S.R. 39: 482-487. (Translated in Zeit. Zuckerind. 83: 78-80. 1958.)
The use of the isotope method in the study of movement of sugars in nlants
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KURSANOV, A. L., M. V. TURKINA, an1d I. M. DUBTN-INA 1953. The use of the isotope method in the study of movement of sugars in nlants. Doklady Aka.d. Nauk SSSR 93: 1115-1118. (Cited in Chemical Abstracts 4642 c. 1954.)
On physiological-biological investigation of fibrovascular bundles in relation to the movement of sugars in plants. Thesis Institute of Plant Physiology The chromatographic examination of sugars in wheat flour Cereal Chenm
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TURKINA, M. V. 1954. On physiological-biological investigation of fibrovascular bundles in relation to the movement of sugars in plants. Thesis. Institute of Plant Physiology. Acad. Sci., U.iS.S.R. Cited by A. A. Prokofvev and A. M. Sobolev. In: Plant Physiol. (A.I.B.S. translationi of Fiziologia Rastenwy) 4: 12-20. 1957. 19. WVILLIAMS, K. T. and A. BEVENUE 1951. The chromatographic examination of sugars in wheat flour. Cereal Chenm. 28: 416-423. 272
The chromatographic examination of sugars in wheat flour
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On physiological-biological investigation of fibrovascular bundles in relation to the movement of sugars in plants
TURKINA, M. V. 1954. On physiological-biological investigation of fibrovascular bundles in relation to the movement of sugars in plants. Thesis. Institute of Plant Physiology. Acad. Sci., U.iS.S.R. Cited by A. A. Prokofvev and A. M. Sobolev. In:
Use of anthrone for quantitative determinations of sugars senarated on chromatograms
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PAvLINOVA. 0. A. 1957. Use of anthrone for quantitative determinations of sugars senarated on chromatograms. Plant Physiol. (A.I.B.S. translation of Fiziologia Rasteny) 4: 97-102.
Forms of mobile sugars in the conducting system of the sugar beet. Doklady Akad
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KURSANOV. A. L. aind M. V. TURKINA 1954. Forms of mobile sugars in the conducting system of the sugar beet. Doklady Akad. Nauk SSSR 95: 885888. (Cited in Chemical Abstracts 8881g. 1954.)
A colorimetric method for the determination of fructose in blood a'nd urine. jour
ROE, J. H. 1934. A colorimetric method for the determination of fructose in blood a'nd urine. jour. Biol. Chem. 107: 15-22.
Phosphoric esters of sut'ar beet. Doklady Akad
PAVLINOVA, 0. A. 1952. Phosphoric esters of sut'ar beet. Doklady Akad. Nauk SSSR 83: 597-600. (Cited in Chemical Abstracts 9668c. 1952.)
The use of the isotope method in the study of movement of sugars in nlants
  • M V Turkina
  • I M Dubtnina
KURSANOV, A. L., M. V. TURKINA, an1d I. M. DUBTNINA 1953. The use of the isotope method in the study of movement of sugars in nlants. Doklady Aka.d. Nauk SSSR 93: 1115-1118. (Cited in Chemical Abstracts 4642 c. 1954.)