Relationship between sucrose accumulation and activities of sucrose-phosphatase, sucrose synthase, neutral invertase and soluble acid invertase in micropropagated sugarcane plants

The activities of sucrose-phosphate synthase (SPS), sucrose synthase (SUSY), neutral invertase (NI) and soluble acid invertase (SAI) regulates sucrose activity in sugarcane were studied. Micropropagated sugarcane plants were obtained from callus cultures of four Mexican commercially available sugarcane varieties characterized by differences in sugar production, and activities of SPS, SUSY, NI, SAI and concentrations of sucrose were monitored in the sugarcane stem. The results indicated that sucrose accumulation was positively and significantly related to an increase in activity of SPS and SUSY and negatively to a reduction in activity of SAI and NI (P<0.05). SPS explained most of the variations found for sucrose accumulation and least for NI. The relationship between activity of SPS, SUSY, NI and SAI in sugarcane stem was similar in each variety.     

Seasonal changes in non-structural carbohydrates and sucrose metabolism enzymes in two Sabina species

Evergreen plants need to store reserves to allow for their survival during the winter months and for new leaf growth in the following spring. In many of the tree species, these reserve functions are mainly carried out by starch, which is degraded to soluble carbohydrates during the dormant season to maintain active respiration and provide protection against freezing. In the present study, two evergreen woody plants, S. przewalskii Kom. (SP) and S. chinensis (Lin.) Ant.(SC), were used to investigate the patterns of seasonal variation in the concentrations of soluble sugars, sucrose, fructose and starch, and the activities of sucrose-phosphate synthase (SPS), sucrose synthase (SUSY), neutral invertase (NI) and soluble acid invertase (SAI). Foliar soluble sugar, sucrose, fructose, and starch concentrations were markedly higher in SC than in SP; moreover, the activities of SPS, SUSY, NI and SAI were also higher in SC than in SP. There were generally higher concentrations of soluble sugars, sucrose and fructose and SPS activities in the winter than in the summer for both Sabina trees, which was consistent with the necessity for protection against freezing; however, opposite results were found with regards to starch concentrations and the activities of SUSY, NI and SAI. In contrast with the activities of SUSY, NI and SAI, the negative correlation observed between SPS and air temperature was likely a reflection of its crucial role in the acquisition of freezing tolerance by sucrose metabolism in the winter. These results suggest that higher carbon reserves do not give S. chinensis (Lin.) Ant. a competitive advantage in tolerating cold temperatures and that only SPS, but not SUSY, NI and SAI, may play a positive role in freezing tolerance by increasing soluble sugar.     

甘蔗节间蔗糖含量与和蔗糖代谢相关的4种酶活性之间的关系剖析

测定和分析2个品种甘蔗节间蔗糖含量与和蔗糖代谢相关的4种酶活性之间关系的结果表明:节间蔗糖含量与酸性转化酶活性成极显著负相关,与蔗糖磷酸合成酶活性呈显著正相关。从通径分析结果可知,4种关键酶中可溶性酸性转化酶和蔗糖磷酸合成酶是对蔗糖含量贡献程度最大的2个酶.     

枇杷果实发育过程中糖积累及相关酶活性变化研究

以'青种'、'霸红'和'鸡蛋白'3个枇杷品种为材料,测定不同果实发育时期果实中蔗糖、葡萄糖和果糖含量以及蔗糖代谢相关酶即酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖积累与酶活性的关系进行了分析.结果表明:在果实膨大期(5月3日)之前,3种枇杷果实的蔗糖、葡萄糖和果糖积累缓慢,之后则迅速积累,存在着明显的转折点;果实成熟(5月23日)之后糖分积累速度趋于平稳.3种枇杷果实在发育过程中转化酶、蔗糖合成酶和蔗糖磷酸合成酶的活性变化与3种糖积累的动态变化趋势相一致.NI和AI活性在果实膨大期之前都较低且没有明显的变化,之后均快速上升;SS和SPS的活性在果实膨大期之前都很低且几乎无变化,随后'鸡蛋白'的活性迅速上升至果实成熟之后便缓慢上升,而'青种'和'霸红'随果实成熟度的增加而升高,但均低于'鸡蛋白'.可见,枇杷果实膨大期是糖分积累代谢活跃期,其糖积累受蔗糖代谢相关酶综合调控.     

‘台农1号’芒果果实发育过程中的糖分积累与相关酶活性研究

以‘台农1号’芒果为材料,测定了果实生长发育过程中淀粉、蔗糖、葡萄糖和果糖含量以及淀粉酶、蔗糖代谢相关酶———酸性转化酶(AI)、中性转化酶(NI)、蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)的活性,并对果实中糖组分与酶活性的关系进行了分析.结果显示,(1)台农1号芒果果实属于单S型生长曲线,发育前期主要积累淀粉、葡萄糖和果糖,果实成熟软化时,淀粉酶活性降至最低,淀粉水解,蔗糖快速积累.(2)酸性转化酶活性在果实整个发育过程中维持最高,完熟时略有降低;蔗糖磷酸合成酶在果实发育前期略有降低,完熟时升至最高;蔗糖合成酶和中性转化酶活性在整个发育期一直很低且较稳定.(3)淀粉含量与淀粉酶活性呈显著正相关,与SPS活性呈极显著负相关,蔗糖、葡萄糖含量均与SPS、SS呈显著、极显著的正相关;果糖含量与SS呈极显著的正相关.研究表明,芒果成熟时淀粉分解、酸性转化酶活性的降低,且蔗糖合成酶和蔗糖磷酸合成酶活性的增加是引起果实蔗糖积累的主要因子.     

网纹甜瓜发育果实糖分积累与蔗糖代谢参与酶的关系

随着网纹甜瓜果实的发育,果实中葡萄糖和果糖的含量增加,蔗糖的快速积累发生在果实发育的中后期,高蔗糖积累型果实中蔗糖积累速率明显快于低蔗糖积累型.蔗糖磷酸合成酶活性在果实发育的前期短暂下降, 而后稳步上升,在果实发育的中后期高蔗糖积累型果实中该酶的活性显著高于低蔗糖积累型果实;随着果实发育,蔗糖合成酶的分解活性降低而合成活性升高.酸性和中性转化酶在未成熟果实中活性较高,而在成熟果实中很低; 高蔗糖积累型果实中酸性转化酶活性显著低于同期低蔗糖积累型果实.合成蔗糖的酶活性小于分解蔗糖的酶活性时蔗糖几乎没有积累.根据这些结果推测,转化酶活性的下降、蔗糖磷酸合成酶活性的增加以及蔗糖合成酶分解活性的下降和合成活性的增加,是引起果实蔗糖积累的主要内在因子.     

Regulation of sucrose storage by amino acid arginine in sugarcane cell suspension cultures

Sugarcane cell cultures were obtained from callus formed on explants derived from young expanding leaves of two early maturing sugarcane varieties viz “CoJ83” and “CoJ86”. The cell cultures were varied with different arginine concentrations in the culture medium. For each cultivar, sucrose content with 20 μM arginine in the culture medium decreased from 3 to 5 days and then increased to 10 days after subculturing. Higher concentration of arginine in the culture medium (60 μM) decreased the sucrose content at different days after subculturing and thus significantly stimulated sucrose mobilization. The activity of sucrose synthase and sucrose phosphate synthase reached maximum while the activity of acid and neutral invertase was minimal in the culture medium with 20 μM arginine. Thus arginine at low concentration (20 μM) enables the cells to accumulate the higher level of sucrose. The optimum level of amino acids can be utilized to regulate the in vivo activity of sucrose synthase, sucrose phosphate synthase and invertase to achieve maximum sucrose accumulation in sugarcane storage tissue.     

Rhythmic growth and carbon allocation in Quercus robur. Sucrose metabolizing enzymes in leaves

The high sucrose phosphate synthase (SPS) capacity and the low soluble acid invertase activity of mature leaves of the first flush of leaves remained stable during second flush development. Conversely, fluctuations of sucrose synthase (SS) activity were in parallel with the sucrose requirement of the second flush. Sucrose synthase activity (synthesis direction) in first flush leaves could increase in 'response' to sink demand constituted by the second flush growth. Only the ptotosynthates provided by flush mature leaves were translocated for a current flush, while the starch content of these leaves remained stable. After their emergence, second flush leaves showed an increase in SPS and SS (Synthetic direction) activities. The high sucrose synthesis in second flush leaves was used for leaf expansion. When young leaves were 30% fully expanded (stage II20), SPS activity showed little change whereas SS activity declined rapidly toward and after full leaf expansion. The starch accumulation in the young leaves occured simultaneously with their expansion. Developing leaves showed a high level of acid invertase activity until maximum leaf expansion (stage II1). In first and second flush leaves, changes in acid invertase activity correlated positively with changes in reducing sugar concentrations. Alkaline invertase and sucrose synthase (cleavage direction) activities showed similar changes with low values when compared with those of acid invertase activity, especially in second flush leaves. The present results suggest that soluble acid invertase was the primary enzyme responsible for sucrose catabolism in the expanding common oak leaf.     

Sucrose-Phosphate Synthase,Sucrose Synthase,and Invertase in Sugar Beet Leaves

The activity of sucrose-phosphate synthase (SPS) in sugar beet (Beta vulgaris L.) leaves was shown to exceed considerably the synthesizing activity of sucrose synthase (SS). The rise in SPS activity was related to the daylight period; i.e., it was associated with the rate of photosynthesis. The highest SPS activity was characteristic of fully expanded source leaves. In young developing leaves (leaves expanded to less than half of their final size), which represent the sink organs, the SPS activity was 2.5 times lower. At all stages of leaf development, the synthesizing SS activity was rather low. The diurnal change of SS activity was independent of photosynthesis and showed a slight rise from 6:00–8:00 p.m. Under field conditions, the highest SPS activity was found in leaves in the terminal stage of their development (105-day-old plants); the synthesizing activity of SS showed little changes during this period. The activity of soluble acid invertase was characteristic of young leaves. In mature leaves, the activity of this enzyme correlated with the daylight period. These changes occurred on the background of low sucrose content in leaves. The regulation of SPS, SS, and invertase activity is discussed. It is supposed that compartmentation of these enzymes in the photosynthesizing cell is important for transport, metabolism, and the osmotic function of sucrose in leaves.     

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.     

Extractable activities and protein content of sucrose-phosphate synthase, sucrose synthase and neutral invertase in trunk tissues of Robinia pseudoacacia L. are related to cambial wood production and heartwood formation

The presence of sucrose synthesizing and degrading enzymes and the correlation of their enzyme activity with cambial growth and heartwood formation are demonstrated in trunks of Robinia pseudoacacia L., black locust. Sucrose is formed by sucrose-phosphate synthase (SPS; EC 2.4.1.14), predominantly in the storage part of the sapwood. In the cambial differentiation zone and the sapwood-heartwood transition zone, both of which constitute carbohydrate sinks, sucrose is primarily cleaved by sucrose synthase (SuSy; EC 2.4.1.13) and a neutral invertase (NI; EC 3.2.1.26). In spring, enhanced activities of SuSy and NI were found in the differentiating xylem tissues. This coincided with elevated SPS rates at the sites of starch mobilization. Heartwood formation in autumn, a period of intense accumulation of phenolics in the innermost living wood tissues, was accompanied by high activities of SuSy and NI. Increased SPS and NI activities in all tissues of winter samples could be correlated with cold acclimation. Probing of SPS and SuSy protein from black locust with heterologous antibodies revealed a subunit size of 130 kDa for SPS and of 89 kDa for SuSy. Both SPS and SuSy exhibited a linear correlation between catalytic activity and amount of enzyme protein with respect to the radial profile from bark to inner core and with respect to the seasonal course. The highest amounts of SuSy-specific mRNA were detected in differentiating xylem in summer and the sapwood-heartwood transition zone in autumn. These data are taken as evidence for a pivotal role of SuSy in supplying carbon skeletons for the biosynthesis of secondary substances in woody axes. Received: 6 May 1998 / Accepted: 28 July 1998     

Sucrose accumulation in sweet sorghum stem internodes in relation to growth

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.     

宁夏枸杞果实糖积累和蔗糖代谢相关酶活性的关系

通过对枸杞果实发育过程中果实生长模式、蔗糖、果糖、葡萄糖和淀粉含量及糖代谢相关酶活性的测定,研究了宁夏枸杞果实生长发育过程中糖的代谢积累与相关酶活性的关系.结果表明:(1)宁夏枸杞果实发育呈双S"曲线,果实主要以积累己糖为主.(2)蔗糖磷酸合成酶(SPS)活性在果实发育初期处于下降的趋势,在花后19d开始上升,果实转色后又逐渐下降;蔗糖合成酶(SS)活性总体表现为SS分解方向的活性大于SS合成方向的活性,说明枸杞果实发育过程中,SS的活性主要以分解方向的为主;酸性转化酶(AI)和中性转化酶(NI)的活性随果实发育呈上升趋势,但在果实成熟后期有所下降,且AI和NI活性高于合成酶类的活性,较高的转化酶类活性促进了果实内部己糖的积累.(3)在枸杞果实生长发育中,葡萄糖和果糖含量与AI和NI均呈极显著正相关,而与其它酶不具有相关性.说明AI和NI在宁夏枸杞果实的糖代谢中起着主要的调控作用.     

Sucrose Metabolism at Three Leaf Development Stages in Bean Plants

Sucrose metabolism was studied at three leaf development stages in two Phaseolus vulgaris L. cultivars, Tacarigua and Montalban. The changes of enzyme activities involved in sucrose metabolism at the leaf development stages were: (1) Sink (9-11 % full leaf expansion, FLE): low total sucrose phosphate synthase (SPS) activity, and higher acid invertase (AI) activity accompanied by low sucrose synthase (SuSy) synthetic and sucrolytic activities. (2) Sink to source transition (40-47 % FLE): increase in total SPS and SuSy activities, decrease in AI activity. (3) Source (96-97 % FLE): high total SPS activity, increased SuSy activities, decreased AI activity. The hexose/sucrose ratio decreased from sink to source leaves in both bean cultivars. The neutral invertase activity was lower than that of AI; it showed an insignificant decrease during the sink-source transition. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effect of sulphite on chlorophyll fluorescence and sucrose metabolism in poplar leaves

Sulphite at concentrations from 0.5 to 5.0 mM was supplied to illuminated, detached poplar (Populus deltoides Bartr. ex Marsh) leaves via the transpiration stream. Chlorophyll a fluorescence parameters, the contents of fructose-2,6-bisphosphate (Fru2,6BP) and starch, and extractable specific activity of sucrose-phosphate synthase (SPS), sucrose synthase (SuSy), acid invertase (AI), neutral invertase (NI), ATP-dependent fructose-6-phosphate 1-phosphotransferase (PFK) and pyrophosphate-dependent fructose-6-phosphate 1-phosphotransferase (PFP) were measured. Chlorophyll fluorescence parameters appeared to be unaffected by sulphite. Application of ≥ 1.0 mM sulphite led to an increase in the content of Fru2,6BP and starch. There was also a decline in the activity of SPS, NI and PFK. On the other hand, the influence of sulphite on the activity of AI and PFP was negligible. Specific activity of SuSy was inhibited by 1.0 and 2.5 mM but activated by 5.0 mM of sulphite. On the basis of the results obtained in the present study, we postulate that sulphite at concentrations ≥ 1.0 mM inhibits primarily sucrose synthesis, favours starch accumulation and has an indirect effect on the sucrolytic activities in poplar leaves.     

甜高粱茎秆不同节间糖分累积与相关酶活性的变化

为了进一步了解甜高粱茎秆糖分代谢的规律,利用高效液相色谱等方法测定了考利、拉马达和MN-2747等3个甜高粱品种成熟期6个节间果糖、葡萄糖和蔗糖含量以及中性转化酶(NI)、可溶性酸性转化酶(SAI)、蔗糖磷酸合成酶(SPS)和蔗糖合成酶(SS)的酶活性,并对其变化规律和相关性进行了分析。结果表明:不同品种间,果糖、葡萄糖和蔗糖含量变化范围较大,分别为2.32～4.34mg/g、2.30～4.14mg/g和35.92～95.92mg/g。随着节间的变化,3个品种果糖和葡萄糖均呈现"U"型变化趋势,而蔗糖无明显的变化规律,只是略有增高的趋势。3个品种成熟期茎秆中NI、SAI、SPS和SS酶活性普遍较低,随着节间的提高均呈现降低的趋势。节间蔗糖含量与SAI酶活性呈显著负相关(R=-0.71,P0.01),与NI、SPS和SS酶活性无明显相关性。SAI可能为甜高粱茎秆糖分代谢的关键调控酶。     

Sucrose phosphate synthase and other sucrose metabolizing enzymes in fruits of various species

Recent reports have suggested that sucrose phosphate synthase (EC 2.4.1.14), a key enzyme in sucrose biosynthesis in photosynthetic “source” tissues, may also be important in some sucrose accumulating “sink” tissues. These experiments were conducted to determine if sucrose phosphate synthase is involved in sucrose accumulation in fruits of several species. Peach (Prunus persica NCT 516) and strawberry (Fragaria x ananassa cv. Chandler) fruits were harvested directly from the plant at various stages of fruit development. Kiwi (Actinidia chinensis), papaya (Carica papaya), pineapple (Ananas comosus) and mango (Mangifera indica) were sampled in postharvest storage over a period of several days. Carbohydrate concentrations and activities of sucrose phosphate synthase, sucrose synthase (EC 2.4.1.13), and acid and neutral invertases (EC 3.2.1.26) were measured. All fruits contained significant activities of sucrose phosphate synthase. Moreover, in fruits from all species except pineapple and papaya, there was an increase in sucrose phosphate synthase activity associated with the accumulation of sucrose in situ. The increase in sucrose concentration in peaches was also associated with an increase in sucrose synthase activity and, in strawberries, with increased activity of both sucrose synthase and neutral invertase. The hexose pools in all fruits were comprised of equimolar concentrations of fructose and glucose, except in the mango. In mango, the fructose to glucose ratio increased from 2 to 41 during ripening as sucrose concentration more than doubled. The results of this study indicate that activities of the sucrose metabolizing enzymes, including sucrose phosphate synthase, within the fruit itself, are important in determining the soluble sugar content of fruits of many species. This appears to be true for fruits which sweeten from a starch reserve and in fruits from sorbitol translocating species, raffinose saccharide translocating species, and sucrose translocating species.     

Differences in sucrose metabolism relative to accumulation of bird-deterrent sucrose levels in fruits of wild and domestic Vaccinium species

We examined variability in sucrose levels and metabolism in ripe fruits of wild and domestic Vaccinium species and in developing fruits of cultivated blueberry (V. ashei and V. corymbosum). The objective was to determine if sufficient variability for fruit sucrose accumulation was present in existing populations to warrant attempts to breed for high-sucrose fruit, which potentially would be less subject to bird predation. Threefold differences in fruit sucrose concentration were found among Vaccinium species, ranging from 19 to 24 mg (g fresh weight)^?1 in V. stamineum and V. arboreum to approximately 7 mg (g fresh weight)^?1 in cultivated blueberry (V. ashei and V. corymbosum) and V. darrowi. Hexose levels were similar among species, ranging from 90 to 110 mg (g fresh weight)^–1, and glucose and fructose were present in equal amounts. Soluble acid invertase (EC 3.2.1.26) activity was negatively correlated with fruit sucrose concentration. There was no apparent correlation between fruit sugar concentration and either sucrose synthase (EC 2.4.1.13) or sucrose phosphate synthase (EC 2.4.1.14) activities, both of which were low for all species studied. Developmental increases in fruit sugar levels of cultivated blueberry followed a pattern similar to that observed in fruit fresh weight accumulation. Hexose concentrations ranged from 6 to 30 mg (g fresh weight)^?1 during the first 60 days after anthesis. Between 60 days and fruit ripening (80 days), hexose levels rose from 30 to 80 mg (g fresh weight)^?1. Sucrose was not detected in fruits until ripening, when low levels were found. Insoluble acid invertase activity was relatively high early in fruit development, decreasing as soluble acid invertase activity increased. Between 60 days and fruit ripening, soluble acid invertase activity increased from 3 to 55 μmol (g fresh weight)^–1 h^–1. Both sucrose synthase and sucrose phosphate synthase activities were low throughout development. The extent of sucrose accumulation in fruits and the degree of variability for this trait among Vaccinium species support the feasibility of developing high sucrose fruits, which would be a potentially valuable addition to current strategies of minimizing crop losses to birds.     

糖代谢相关酶在灵武长枣叶片和果柄糖积累中的作用

以不同发育时期灵武长枣为试材,测定果实生长发育过程中叶片、果柄可溶性糖含量及蔗糖代谢相关酶活性的变化,探讨果实生长发育过程中叶片、果柄糖的积累与蔗糖代谢相关酶活性的关系。结果表明:(1)灵武长枣叶片、果柄均主要以积累蔗糖为主,叶片、果柄中葡萄糖和果糖含量的变化平缓且随果实发育略有上升,蔗糖含量则呈先下降后迅速上升的趋势,且蔗糖含量始终高于葡萄糖和果糖的含量。(2)在果实的整个发育期,叶片和果柄的酸性转化酶(AI)活性均远高于中性转化酶(NI),AI在前期升高后变化较平稳,而蔗糖合成酶(SS)和蔗糖磷酸合成酶(SPS)活性的变化各不相同。(3)SS分解方向酶活性(SSd)对叶片和果柄蔗糖的积累具有重要的调节作用。研究认为,蔗糖合成酶分解方向酶活性(SSd)对灵武长枣叶片和果柄蔗糖的积累起主要的调控作用。