Regulation by sucrose of storage compounds breakdown in germinating seeds of yellow lupine (Lupinus luteus L.), white lupine (Lupinus albus L.) and Andean lupine (Lupinus mutabilis Sweet): I. Mobilization of storage protein

Research of the regulatory function of sucrose in storage protein breakdown was conducted on isolated embryo axes, excised cotyledons and whole seedlings of three lupine species grown in vitro on medium with 60 mM sucrose or without the sugar. Sucrose stimulated growth of yellow, white and Andean lupine isolated embryo axes and cotyledons but growth of seedlings was inhibited. Dry matter content was higher in sucrose-fed isolated organs and in seedling organs. Ultrastructure research revealed that lack of sucrose in the medium caused enhancement in storage protein breakdown. Protein deposits in cotyledons were smaller as well as soluble portion content in all studied organs was lower when there was no sucrose in the medium. In the same conditions, the activity of glutamate dehydrogenase was significantly higher. Increase in vacuolization of cells of white lupine root meristematic zone cells was observed and induction of autophagy in young carbohydrate-starved embryo axes is discussed.     

Changes in soluble carbohydrates and related enzymes induced by low temperature during early developmental stages of quinoa (Chenopodium quinoa) seedlings

Low temperature represents one of the principal limitations in species distribution and crop productivity. Responses to chilling include the accumulation of simple carbohydrates and changes in enzymes involved in their metabolism. Soluble carbohydrate levels and invertase, sucrose synthase (SS), sucrose-6-phosphate synthase (SPS) and alpha-amylase activities were analysed in cotyledons and embryonic axes of quinoa seedlings grown at 5 degrees C and 25 degrees C in the dark. Significant differences in enzyme activities and carbohydrate levels were observed. Sucrose content in cotyledons was found to be similar in both treatments, while in embryonic axes there were differences. Invertase activity was the most sensitive to temperature in both organs; however, SS and SPS activities appear to be less stress-sensitive. Results suggest that 1) metabolism in germinating perispermic seeds would be different from endospermic seeds, 2) sucrose futile cycles would be operating in cotyledons, but not in embryonic axes of quinoa seedlings under our experimental conditions, 3) low temperature might induce different regulatory mechanisms on invertase, SS and SPS enzymes in both cotyledons and embryonic axes of quinoa seedlings, and 4) low temperature rather than water uptake would be mainly responsible for the changes observed in carbohydrate and related enzyme activities.     

Modulation of Reserve Mobilization by Sucrose,Glutamine, and Abscisic Acid During Seedling Establishment in Sunflower

We carried out in vitro feeding experiments using sunflower as a model to differentiate the modulatory effects of metabolites (sucrose and glutamine) and hormones (gibberellic acid and abscisic acid) on reserve mobilization, metabolite partitioning, and key enzyme activities. Exogenous sucrose negatively not only modulated the mobilization of carbon reserves (oils and starch), but it also delayed the degradation of nitrogen reserves (storage proteins) in the cotyledons. Similarly, exogenous glutamine negatively not only modulated storage protein hydrolysis, but it also retarded oil and starch degradation. Different from the metabolites, exogenous abscisic acid affected only the mobilization of oils and storage proteins. Sucrose and glutamine caused non-reducing sugar accumulation in the cotyledons and axis, but abscisic acid did not change the content of these compounds in both seedling parts. Curiously, glutamine failed to cause amino acid accumulation in the cotyledons and abscisic acid increased the amino acid content in both cotyledons and axis. Gibberellic acid did not stimulate reserve mobilization and metabolite consumption. Although the mobilization of oils, storage proteins, and starch has been delayed by sucrose and glutamine, these metabolites augmented the activity of isocitrate lyase, acid proteases, and amylases. Only abscisic acid reduced amylase activity and increased glutamine synthetase activity. Accordingly, sucrose and glutamine exert a “crossed effect” on reserve mobilization, that is, sucrose delays storage protein hydrolysis and glutamine retards oil and starch degradation. These effects may be mediated by non-reducing sugars and they are, at least in part, different from those exerted by abscisic acid.     

干旱胁迫下紫花苜蓿幼苗非结构性碳水化合物代谢对NO的响应

以紫花苜蓿（Medicago sativa）为材料,采用盆栽试验方法,用聚乙二醇（PEG-6000）作为渗透介质模拟干旱胁迫,外源喷施NO供体硝普钠,NO清除剂（carboxy-PTIO,cPTIO）,对紫花苜蓿幼苗叶片、根系中非结构性碳水化合物含量及相关酶活性的变化进行研究,探讨NO对紫花苜蓿耐旱机制的作用。结果表明：外源NO促进了紫花苜蓿叶片中淀粉的分解、根系中淀粉的积累,提高叶片及根系中可溶性糖（蔗糖、果糖和葡萄糖）含量,降低了渗透势,促进细胞吸水,缓解干旱造成的损伤。此外,外源NO能提高干旱胁迫下紫花苜蓿叶片中蔗糖合成酶（SS）、酸性转化酶（AI）和中性转化酶（NI）活性,降低了蔗糖磷酸合成酶（SPS）的活性,提高根系中SS、SPS和转化酶活性,使蔗糖的合成与分解处于高水平的动态平衡,增强了紫花苜蓿的抗旱性。而NO清除剂cPTIO则会不同程度的抑制紫花苜蓿幼苗中非结构性碳水化合物（NSC）及其相关酶活性。因此,NO可以通过调控NSC的代谢响应干旱胁迫,缓解干旱胁迫造成的不利影响,在紫花苜蓿的抗旱中扮演着重要的角色。     

Sugar metabolism in germinating soybean seeds: evidence for the sorbitol pathway in soybean axes

Characterization of sugar content and enzyme activity in germinating soybean (Glycine max L. Merrell) seeds led to the discovery of sorbitol accumulating in the axes during germination. The identity of sorbitol was confirmed by relative retention times on high-performance liquid chromatography and gas liquid chromatography and by mass spectra identical with authentic sorbitol. Accumulation of sorbitol in the axes started on day 1 of germination as sucrose decreased and glucose and fructose increased. Sucrose also decreased in the cotyledons, but there was no accumulation of sorbitol, glucose, or fructose. Accumulation of sorbitol and hexoses was highly correlated with increased invertase activity in the axes, but not with sucrose synthase and sucrose phosphate synthase activities. Sucrose synthase activity was relatively high in the axes, whereas the activity of sucrose phosphate synthase was relatively high in the cotyledons. Ketose reductase and aldose reductase were detected in germinating soybean axes, but not in cotyledons. Fructokinase and glucokinase were present in both axes and cotyledons. The data suggest a sorbitol pathway functioning in germinating soybean axes, which allows for the interconversion of glucose and fructose with sorbitol as an intermediate.     

Effect of Kinetin on Starch and Sucrose Metabolising Enzymes in Salt Stressed Chickpea Seedlings

Higher amylase activity in cotyledons of kinetin treated salt stressed (75 mM NaCl) chickpea (Cicer arietinum L. cv. PBG-1) seedlings, as compared to salt stressed seedlings was observed during a growth period of 7 d. The activities of acid and alkaline invertases were maximum in shoots and minimum in cotyledons under all conditions. The reduced shoot invertase activities under salt stress were enhanced by kinetin with a simultaneous increase in reducing sugar content. Kinetin increased the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in both the cotyledons and shoots of stressed seedlings. Kinetin appears to increase the turnover of sucrose in the shoots of stressed seedlings.     

Regulation by sucrose of storage compounds breakdown in germinating seeds of yellow lupine (Lupinus luteus L.), white lupine (Lupinus albus L.) and Andean lupine (Lupinus mutabilis Sweet). II. Mobilization of storage lipid

Research of the regulatory function of sucrose in storage lipid breakdown was conducted on isolated embryo axes, excised cotyledons and whole seedlings of three lupine species grown in vitro on medium with 60 mM sucrose or without the sugar. Lack of sucrose in the medium caused significant increase in total lipid content in yellow, white and Andean lupine isolated embryo axes but in Andean lupine seedling cotyledons and excised cotyledons, lipid level was clearly lower in carbohydrates deficient conditions. Sucrose caused no significant effect on fatty acids spectra. The main fatty acid in yellow lupine seeds was linoleic acid, in white lupine oleic acid and in Andean lupine both oleic and linoleic acids. The main phospholipid in organs of three lupine species was phosphatidylcholine. In sugar-deficient conditions, content of phosphatidylcholine and some others phospholipids was decreased. The peculiar features of regulation by sugars of storage lipid breakdown in germinating lupine seeds and induction of autophagy in young carbohydrate starved embryo axes is discussed.     

Raffinose in seedlings of winter vetch (<Emphasis Type="Italic">Vicia villosa</Emphasis> Roth.) under osmotic stress and followed by recovery

During germination of winter vetch (Vicia villosa Roth.) seeds, the degradation of raffinose family oligosaccharides and galactosyl pinitols occurred faster in axis than in cotyledons. After 7 days of germination, all α-d-galactosides disappeared and the soluble carbohydrates in seedling tissues consisted of d-pinitol, sucrose, fructose, glucose and myo-inositol. Osmotic stress caused by incubation of seedlings in PEG 8000 solution (−0.5, −1.0, and −1.5 MPa) for 48 h induced the activity of crucial enzymes of the RFOs pathway, i.e. galactinol synthase and raffinose synthase, in both the root and epicotyl but not in cotyledons. The root and epicotyl accumulated elevated amounts of galactinol and raffinose as the osmotic potential was lowered. This process was transient because when PEG solution was replaced with water, galactinol and raffinose were degraded, thus confirming their direct involvement in the response of tissues to osmotic stress. Among other soluble carbohydrates, only sucrose accumulated in response to stress. The results did not show potential role of d-pinitol in the adjustment of winter vetch seedlings to osmotic stress.     

Water stress enhances beta-amylase activity in cucumber cotyledons

Cotyledons detached from 4-d-old cucumber (Cucumis sativus L.) seedlings were subjected to water stress (air-drying or PEG-treatment) to examine the effects of the stress on carbohydrate metabolism. Amylolytic activity in the cotyledon was increased about 6-fold by water stress within 1 d. The substrate specificity and the action pattern indicated that beta-amylase is responsible for the activity. Activities of azocaseinase, malate dehydrogenase and triose-phosphate isomerase were not affected by water stress, indicating that the effect of the stress on beta-amylase is rather specific. Cycloheximide-treatment strongly reduced the enhancement of beta-amylase activity. The hypocotyl of cucumber seedlings also exhibited an increase in the enzyme activity when subjected to water stress. The major free sugars in cucumber cotyledons were glucose, fructose, maltose, and sucrose; sucrose being the most abundant. Sucrose content in excised, unstressed cotyledons increased markedly during the incubation. Changes in other free sugars were small compared with that of sucrose. Starch also accumulated in unstressed cotyledons. In stressed cotyledons more sucrose and less starch accumulated than in unstressed ones. Such results were discussed in relation to the enhancement of beta-amylase activity.     

盐分和水分胁迫对芦荟幼苗渗透调节和渗调物质积累的影响

用不同浓度NaCl和等渗聚乙二醇(PEG 6000)处理芦荟(Aloe vera L.)幼苗,10 d后测定叶片相对生长速率和厚度、叶片中主要有机溶质、无机离子含量及渗透调节能力.结果表明,-0.44、-0.88 MPa NaCl和PEG处理使芦荟叶片的相对生长速率和叶片厚度明显下降,且盐胁迫对幼苗生长的抑制和叶片含水量降低的效应明显高于等渗的水分胁迫,其叶片渗透调节能力随处理渗透势的降低而增加, -0.88 MPa PEG胁迫的芦荟幼苗的渗透调节能力高于等渗盐分胁迫.在主要渗透调节物质可溶性糖、有机酸、K 、Ca2 和Cl-中,-0.88 MPa PEG处理下含量比相同渗透势的NaCl处理下显著增加的是有机溶质,因此推断有机溶质含量高是PEG胁迫下渗透调节能力较强的主要因素.     

Low-temperature effect on enzyme activities involved in sucrose–starch partitioning in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) seedlings

The effect of low temperature on growth, sucrose–starch partitioning and related enzymes in salt-stressed and salt-acclimated cotyledons of quinoa (Chenopodium quinoa Willd.) was studied. The growth of cotyledons and growing axes in seedlings grown at 25/20 °C (light/dark) and shifted to 5/5 °C was lower than in those only growing at 25/20 °C (unstressed). However, there were no significant differences between low-temperature control and salt-treated seedlings. The higher activities of sucrose phosphate synthase (SPS, EC 2.4.1.14) and soluble acid invertase (acid INV, EC 3.2.1.25) were observed in salt-stressed cotyledons; however, the highest acid INV activity was observed in unstressed cotyledons. ADP-glucose pyrophosphorylase (ADP-GPPase, EC 2.7.7.27) was higher in unstressed cotyledons than in stressed ones. However, between 0 and 4 days the highest value was observed in salt-stressed cotyledons. The lowest value of ADP-GPPase was observed in salt-acclimated cotyledons. Low temperature also affected sucrose synthase (SuSy, EC 2.4.1.13) activity in salt-treated cotyledons. Sucrose and glucose were higher in salt-stressed cotyledons, but fructose was essentially higher in low-temperature control. Starch was higher in low-temperature control; however, the highest content was observed at 0 day in salt-acclimated cotyledons. Results demonstrated that low temperature induces different responses on sucrose–starch partitioning in salt-stressed and salt-acclimated cotyledons. Data also suggest that in salt-treated cotyledons source–sink relations (SSR) are changed in order to supply soluble sugars and proline for the osmotic adjustment. Relationships between starch formation and SuSy activity are also discussed.     

Sucrose Is a Nonaccumulated Osmoprotectant in Sinorhizobium meliloti

Intracellular accumulation of sucrose in response to lowered water activity seems to occur only in photosynthetic organisms. Here we demonstrate, for the first time, the potent ability of this common sugar, supplied exogenously, to reduce growth inhibition of Sinorhizobium meliloti cells in media of inhibitory osmolarity. Independently of the nature of the growth substrates and the osmotic agent, sucrose appears particularly efficient in promoting the recovery of cytoplasmic volume after plasmolysis. Surprisingly, sucrose is not accumulated by the bacteria at an osmotically efficient level. Instead, it strongly stimulates the accumulation of the main endogenous osmolytes glutamate and N-acetylglutaminylglutamine amide (NAGGN). Examining cell volume changes during the hyperosmotic treatment, we found a close correlation between the enhancement of the osmotically active solute pool and the increase in cell volume. Sucrose shares several features with ectoine, another nonaccumulated osmoprotectant for S. meliloti. Overall, osmoregulation in S. meliloti appears to be strongly divergent from that in most bacteria.     

甘草叶片渗透调节物质及蔗糖代谢相关酶对干旱胁迫的响应特性

该研究以甘草幼苗为试材,采用盆栽自然干旱方法,设计对照(CK)、轻度(LS)、中度(MS)、重度(SS)干旱胁迫处理,测定分析甘草叶片的渗透调节物质及蔗糖代谢相关酶[蔗糖磷酸合成酶(SPS)、蔗糖合成酶合成方向(Ss+)、蔗糖合成酶分解方向(Ss-)、中性转化酶(NI)、酸性转化酶(AI)、淀粉磷酸化酶(SP)]活性的变化,以探讨甘草的渗透调节特性以及糖分调节的酶学机制,揭示甘草对干旱胁迫的响应机理。结果显示:(1)随着干旱胁迫程度的加剧,甘草叶片可溶性糖、可溶性蛋白和脯氨酸含量呈逐渐增加的趋势,束缚水/自由水的比值呈先增加后降低的趋势。(2)随着干旱胁迫程度的加剧,甘草叶片蔗糖、葡萄糖、果糖含量均呈先升高后降低的趋势,但不同胁迫强度出现峰值的时间不同;其中在CK和LS干旱胁迫时蔗糖含量淀粉含量葡萄糖含量果糖含量,在MS和SS干旱胁迫时淀粉含量葡萄糖含量蔗糖含量果糖含量,表明随着干旱程度的增加,甘草叶片中蔗糖转化成了淀粉。(3)随着干旱胁迫程度的加重,甘草叶片的SPS活性呈先升高后降低的趋势,Ss活性和Inv(蔗糖转化酶)活性呈逐渐升高的趋势,SP活性呈逐渐降低的趋势;各胁迫处理的Ss+活性与CK差异不显著,而Ss-活性与CK差异显著,并且Ss-活性在各胁迫处理下远大于Ss+活性,表明甘草叶片Ss-活性在蔗糖代谢过程中占主导作用。(4)相关分析结果显示,在LS中,NI与蔗糖呈负相关关系,Ss-与淀粉呈显著正相关关系、与蔗糖呈负相关关系;在MS中,蔗糖和葡萄糖与SPS、Ss+、Ss-、NI和AI均呈正相关关系,与SP呈负相关关系;在SS中,SP和NI与蔗糖呈正相关关系,而与淀粉呈负相关关系;表明在轻度干旱处理下,Ss参加了蔗糖的分解,继而合成淀粉;在中度和重度干旱条件下,SP主要催化淀粉的分解来增加蔗糖含量以此平衡蔗糖代谢。     

The Effect of Sucrose on Primordium Development and on Protein and RNA Levels in Detached Cotyledons of Sinapis alba L.

Cotyledons of Sinapis alba cultured in the light on filter-papermoistened with water initiated root primordia within 2 daysafter detachment. These increased in size and penetrated thebase of the petiole after a further 3 days. Culture in sucrosesolution in the light inhibited root formation mainly by affectingthe extension phase when many primordia regressed resultingin a decline in the numbers of primordia per petiole. When cotyledonswere cultured in the dark no primordia were initiated in water,but sucrose promoted root formation. Levels of RNA rose to a peak value in the terminal petiole segmentat a time when primordia were being initiated in this region,protein reached a peak 2 days later. This pattern was much lessevident in the subterminal segments. It did not occur at allin cotyledons cultured in sucrose in the light where a smallinitial increase in RNA and protein was followed by a rapiddecline. The level of RNA and protein in the terminal segmentin light-cultured cotyledons in water was related to the numberof light periods given following detachment as was the percentageof cotyledons which formed roots. The effect of sucrose on RNAand protein content was less marked when cotyledons were transferredfrom sucrose to water instead of being maintained in sucrosethroughout. Sucrose clearly modifies the biochemical and structural changestaking place at the petiole base having particularly inhibitoryeffects on the extension phase of the primordia. The evidenceindicates that sucrose could be causing premature ageing ofcells forming the primordia.     

Sucrose biosynthesis in Dunaliella

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.Abbreviations F-6-P fructose 6-phosphate - UDP uridine biphosphate - UDPG uridine biphosphoglucose     

Osmoregulation in hypocotyls of etiolated mung bean seedlings with or without cotyledons in response to water-deficient stress

Effects of water-deficient stress and cotyledon excision on osmoregulation in hypocotyls of dark-grown mung bean seedlings were studied, and following results were obtained. Water-deficient stress inhibited hypocotyl elongation either in intact or decotylized seedlings. The inhibition was more conspicuous in decotylized seedlings than in intact ones. Water-deficient stress decreased osmotic potential in hypocotyls, while cotyledon excision increased it. The concentrations of soluble sugars, free amino acids and potassium ions in hypocotyls of intact or decotylized seedlings increased in response to water-deficient stress. Cotyledon excision reduced the concentration of soluble sugars and free amino acids, but it did not change the concentration of potassium ions, suggesting that a part of soluble sugars and free amino acids is transported from cotyledons. Unlike cotyledon excision, excision of the apex or roots had no influence on osmoregulation in response to water-deficient stress. Segments excised from hypocotyls had the ability to osmoregulate in response to water-deficient stress. Based on these results, the role of cotyledons in osmoregulation in response to water-deficient stress and quantitative relationships between osmotic potential and hypocotyl elongation in etiolated mung bean seedlings are discussed.     

Acclimation of potato plants to polyethylene glycol-induced water deficit II. Contents and subcellular distribution of organic solutes

Potato plants (Solanum tuberosum cv. Désirée) were grown hydroponically and subjected to water deficit induced by addition of 10% (w/v) PEG 6000. The potato plants were able to grow under water deficit by accumulating organic solutes (osmoregulation). Osmoregulation occurred in two phases. During the initial 2d hexoses were accumulated, and after 7 d of PEG treatment osmotic adjustment was mostly due to the accumulation of amino acids, especially proline, which accumulated up to 150 times the control content. Sucrose contents remained unchanged in leaves of PEG-treated plants compared with controls, whereas the starch content decreased during PEG treatment.In control leaves, the hexoses and malate were compartmented in the vacuole and sucrose was found in the cytosol and vacuole. Amino acids were distributed between the cytosol and stroma, but only minor amounts of amino acids could be detected in the vacuole. Under water deficit the subcellular distribution of hexoses, malate and sucrose remained unchanged. Most amino acids showed a slight to moderate higher concentration in the vacuole under water deficit. Proline, the metabolite contributing mainly to osmoregulation, was concentrated mostly in the chloroplast and the cytosol. This underlines the important role of proline as the osmolyte under water deficit.     

Diverse regulation by sucrose of enzymes involved in storage lipid breakdown in germinating lupin seeds

The regulatory function of sucrose in the activity of lipid-degrading enzymes was investigated in germinating seeds of yellow lupin (Lupinus luteus L.), white lupin (Lupinus albus L.) and Andean lupin (Lupinus mutabilis Sweet). The study was conducted on isolated embryo axes, excised cotyledons and seedlings cultured in vitro for 96 h on medium with 60 mM sucrose or without the sugar. The activity of lipase (lipolysis), acyl-CoA oxidase and catalase (fatty acid β-oxidation) was enhanced in all studied organs cultured on medium without sucrose. The activity of cytosolic aconitase (glyoxylate cycle) was stimulated by sucrose in seedling axes and isolated embryo axes, whereas in seedling cotyledons and excised cotyledons, it was inhibited. The regulatory function of sucrose in phosphoenolpyruvate carboxykinase (gluconeogenesis) was observed only in isolated embryo axes and the activity was lower in carbohydrate deficiency conditions. The peculiar features of storage lipid breakdown in germinating lupin seeds and its regulation by sucrose are discussed.     

Sucrose transport by seedlings of Ricinus communis L: the export of sucrose from the cotyledons to the hypocotyl as a function of sucrose concentration in the cotyledons

Abstract Using seedlings of Ricinus communis L. sucrose export from the cotyledons to the hypocotyl and roots was measured at different levels of sucrose concentration in the cotyledons. Sucrose export followed Michaelis-Menten kinetics with a half-saturation of export at 35 mM sucrose in the cotyledons. A maximal export flux of 90 μmol h^?l g^?1 fresh weight of the cotyledons was obtained. Both these figures coincide with those obtained for sucrose uptake into the cotyledons. It is postulated that sucrose uptake and sucrose export occurs by the same mechanism and possibly by the same cells which then would have to be part of the phloem. Since sucrose uptake has been shown to proceed as proton-sucrose co-transport, phloem loading might also be energized by the protonmotive potential difference. The data, furthermore, are difficult to reconcile with the symplastic route of phloem loading.     

Import of Sucrose and its Partitioning in the Synthesis of Galactomannan and Raffinose-oligosaccharides in the Developing Guar (Cyamopsis tetragonolobus) Seed

Import of sucrose and its transformation to galactomannan andraffinose-oligosaccharides have been studied in the developingguar seed. The amount of galactomannan gradually increased withthe ageing of the seed. During the entire period of pod development,sucrose constituted the major portion of the free sugars inthe seed (both endosperm and cotyledons) as well as in the podwall. Besides myo-inositol, the free sugars detected in thedeveloping endosperm and cotyledons were glucose, fructose,raffinose and stachyose. Some compounds, possibly glycosides(RG values higher than that of fructose), were also detectedin the endosperm. In the later stages of seed development, therelative proportion of raffinose in the free sugars increased,reaching 50% of the total free sugars in 77-d-old cotyledons.With pod maturity, the activities of soluble acid and boundacid invertases in the pod wall increased manifold with a concomitantdecline in the non-reducing sugar content. These enzymes seemto be involved in the mobilization of sucrose from this fruitingstructure into the seed. An increased synthesis of raffinose-oligosaccharidesboth in the endosperm and cotyledons was associated with highactivities of soluble acid invertase (pH 4.8) and sucrose-UDPglucosyl transferase in these tissues. Feeding uniformly labelled¹⁴C-sugars to the detached intact pods as well as to the isolatedendosperm and cotyledons resulted in labelling of all endogenousfree sugars and galactomannan. The uptake and incorporationinto galactomannan of ¹⁴C was stimulated by Co²⁺, Mn²⁺ and Mg²⁺.Except for mannose, a major proportion of the ¹⁴C from glucose,fructose and sucrose appeared in sucrose in both endosperm andcotyledons indicating a fast reconstitution of sucrose in situ.Based on the present results, a possible mode of transformationof sucrose to galactomannan and raffinose-oligosaccharides hasbeen proposed. Key words: Sucrose, galactomannan, raffinose-oligosaccharides, invertase, sucrose-UDP glucosyl transferase, ¹⁴C-incorporation, guar seed