Ratio Of Hexose Research Articles

Strigolactones Might Regulate Ovule Development after Fertilization in Xanthoceras sorbifolium.

Strigolactones (SLs) were recently defined as a novel class of plant hormones that act as key regulators of diverse developmental processes and environmental responses. Much research has focused on SL biosynthesis and signaling in roots and shoots, but little is known about whether SLs are produced in early developing seeds and about their roles in ovule development after fertilization. This study revealed that the fertilized ovules and early developing pericarp in Xanthoceras sorbifolium produced minute amounts of two strigolactones: 5-deoxystrigol and strigol. Their content decreased in the plants with the addition of exogenous phosphate (Pi) compared to those without the Pi treatment. The exogenous application of an SL analog (GR24) and a specific inhibitor of SL biosynthesis (TIS108) affected early seed development and fruit set. In the Xanthoceras genome, we identified 69 potential homologs of genes involved in SL biological synthesis and signaling. Using RNA-seq to characterize the expression of these genes in the fertilized ovules, 37 genes were found to express differently in the fertilized ovules that were aborting compared to the normally developing ovules. A transcriptome analysis also revealed that in normally developing ovules after fertilization, 12 potential invertase genes were actively expressed. Hexoses (glucose and fructose) accumulated at high concentrations in normally developing ovules during syncytial endosperm development. In contrast, a low ratio of hexose and sucrose levels was detected in aborting ovules with a high strigolactone content. XsD14 virus-induced gene silencing (VIGS) increased the hexose content in fertilized ovules and induced the proliferation of endosperm free nuclei, thereby promoting early seed development and fruit set. We propose that the crosstalk between sugar and strigolactone signals may be an important part of a system that accurately regulates the abortion of ovules after fertilization. This study is useful for understanding the mechanisms underlying ovule abortion, which will serve as a guide for genetic or chemical approaches to promote seed yield in Xanthoceras.

Differential Expression of Sugar Uniporter Genes of the SWEET Family in the Regulation of Qualitative Fruit Traits in Tomato Species (Solanum Section Lycopersicon)

Tomato (Solanum lycopersicum L.) is an important crop and, due to the existence of wild relatedspecies (Solanum section Lycopersicon), a model for studying the development of the fleshy fruit. In thestudy, expression analysis of sugar uniporter genes SWEET1а, 1b, 1e, 3, 7a, 10a, 12c, 14, and 15 in tomatospecies and cultivars was carried out. In cv. Heinz (S. lycopersicum), genes that are most active in roots(SWEET1e, 3, 10a, and 12c), leaves (SWEET1a, 1e, 3, 10a, and 12c) and flowers (SWEET1a, 1b, 7a, 10a,12s, 14, and 15) were revealed. The growth of the fruit is accompanied by an increase in the level of theSWEET 110a and 12c transcripts; maturation of the fruit is accompanied by an increase in the level of theSWEET 1a and 15 transcripts. Differential expression of the SWEET1a, 1b, 12c, and 15 genes in the ripe fruitof inbred lines obtained from crossing of S. lycopersicum cv. M82 × S. pennellii was demonstrated. qRT-PCRanalysis showed that the expression of the SWEET1a and 12c genes is common for ripe fruit of the analyzedtomato species, while the expression of the SWEET1b and 10a genes is common for S. pennellii, S. habrochaites,and S. cheesmaniae. It was determined that the fructose : glucose ratio is equimolar in the accessionsexcept for cv. Black Jack and White Beauty (fructose : glucose ≥ 1.10). Correlations between the level ofSWEET gene transcripts and the ratio of hexoses was not revealed.

Hawkmoth pollination of the scented South African fynbos endemic Erica cylindrica Thunb. (Ericaceae)

The predictive power of pollination syndromes has been demonstrated for many South African plant species with specialized pollination systems, but has rarely been tested in the florally diverse genus Erica. Here we evaluate the hypothesis that Erica cylindrica is moth-pollinated, based on its tubular, pale, and strongly scented flowers. Pollinator observations revealed exclusive nocturnal flower visitation by several hawkmoth species, and assessment of pollen loads confirmed that two hawkmoth species carried Erica pollen grains on their proboscises. Floral scent showed no clear periodicity in emission, but was dominated by benzenoid scent compounds including benzaldehyde, benzyl alcohol, benzyl acetate, and eugenol that are known to elicit antennal responses in hawkmoths. The pale cream flower colour was characterized by uniform reflectance across the human-visible light spectrum and a small secondary peak in the UV region. The volume of nectar produced was small, but the intermediate sugar concentration and sucrose:hexose ratio of 0.7 are consistent with hawkmoth pollination. More than three-quarters of flowers in an inflorescence are oriented upwards, which is highly unusual among South African ericas but has been shown to be adaptive in other hawkmoth-pollinated flowers. Anther-ring disruption indicated that at least 62% of flowers received visits and was associated with pollen deposition in 68% of visited flowers, suggesting that visitors are effective pollinators. Our study provides evidence for hawkmoth pollination of an Erica species, a system hitherto rarely recorded in Ericaceae. Several floral traits are consistent with the hawkmoth pollination syndrome, but further work is required to confirm the functional significance of these traits and the level of specialization in this hawkmoth pollination system.

Waterlogging increases organic carbon decomposition in grassland soils

Drainage increases soil organic carbon (SOC) mineralization, but waterlogging will not necessarily slow the SOC decomposition. We investigated the effects of water regime (anaerobic vs. aerobic conditions) on SOC mineralization in adjacent wetland and grassland soils with contrasting biochemical properties in the east Tibetan Plateau. Biochemical characteristics of SOC (compositions of non-cellulosic and amino polysaccharides) were analyzed, then soils were moistened to 70% of water-holding capacity (aerobic) or saturated (anaerobic) and incubated at 25 °C for 95 days. The non-cellulosic sugar content in SOC was similar in wetland and meadow soils, but the mass ratio of hexoses (galactose plus mannose or rhamnose plus fucose) to pentoses (arabinose plus xylose) was three-fold greater in meadows than wetlands. Furthermore, there was three times more accumulation of microbial residues (sum of glucosamine, mannosamine, galactosamine, and muramic acid) in SOC, and more fungal than bacterial necromass in the meadow than wetland soils. This suggests slower transformation of plant litter by microorganisms, and thus less accumulation of microbial products in the SOC of wetlands than meadows. Meadow soils had more microbial biomass and higher activities of β–glucosidase, phenol oxidase, and urease per unit of SOC than wetland soils. During the 95-day incubation, C loss (as CO2) per unit of SOC was 55–73% greater in anaerobic than aerobic meadow soils, but was 59–64% less from wetland soils under anaerobic conditions than aerobic conditions. Thus, SOC decomposition in anaerobic conditions was dependent on the degree of SOC degradation, which was related to the initial proportion of plant and microbial residues. We addressed the importance of biochemical nature in regulating SOC decomposition under anaerobic conditions. We conclude that both the wetland drainage and grassland waterlogging increase SOC mineralization (measured as CO2 evolution) in alpine areas.

Proteomics and post-secretory content adjustment of Nicotiana tabacum nectar.

The tobacco nectar proteome mainly consists of pathogenesis-related proteins with two glycoproteins. Expression of nectarins was non-synchronous, and not nectary specific. After secretion, tobacco nectar changed from sucrose rich to hexose rich. Floral nectar proteins (nectarins) play important roles in inhibiting microbial growth in nectar, and probably also tailoring nectar chemistry before or after secretion; however, very few plant species have had their nectar proteomes thoroughly investigated. Nectarins from Nicotiana tabacum (NT) were separated using two-dimensional gel electrophoresis and then analysed using mass spectrometry. Seven nectarins were identified: acidic endochitinase, β-xylosidase, α-galactosidase, α-amylase, G-type lectin S-receptor-like serine/threonine-protein kinase, pathogenesis-related protein 5, and early nodulin-like protein 2. An eighth nectarin, a glycoprotein with unknown function, was identified following isolation from NT nectar using a Qproteome total glycoprotein kit, separation by SDS-PAGE, and identification by mass spectrometry. Expression of all identified nectarins, plus four invertase genes, was analysed by qRT PCR; none of these genes had nectary-specific expression, and none had synchronous expression. The total content of sucrose, hexoses, proteins, phenolics, and hydrogen peroxide were determined at different time intervals in secreted nectar, both within the nectar tube (in vivo) and following extraction from it during incubation at 30°C for up to 40h in plastic tubes (in vitro). After secretion, the ratio of hexose to sucrose substantially increased for in vivo nectar, but no sugar composition changes were detected in vitro. This implies that sucrose hydrolysis in vivo might be done by fixed apoplastic invertase. Both protein and hydrogen peroxide levels declined in vitro but not in vivo, implying that some factors other than nectarins act to maintain their levels in the flower, after secretion.

Spent sulphite liquor utilization by xylose-assimilating yeast pachysolen tannophilus, capable of bioethanol producing

The xylose-assimilating capacity of yeast Pachysolen tannophilus to utilize sugars in spent sulphite liquor samples (pulp mill waste) with a different concentration of hexoses and pentoses was studied. The consumption of hexoses (D-glucose, D-mannose, D-galactose) and pentose (D-xylose) in such substrates reached 90.0-97.5% and 49.12-67.45%, respectively. The ethanol production from sugars in spent sulphite liquor by different strains of the yeast P. tannophilus was demonstrated. The maximum specific rate and ethanol yield reached 9.32-11.45 g l-1 and 0.28-0.37 g g sugars-1, respectively. Thus, the principle possibility of using xylose-assimilating P. tannophilus yeast to obtain bioethanol from sulfite liquor with a different ratio of hexoses and pentoses was proved. According to theoretical calculations, this method will provide up to 42.6 liters of ethanol from 100 kg of sulfite liquor containing 55.6% D-xylose, 24.7% D-glucose, 8.7% D-mannose, 7.6% D-galactose, 3.7% L-arabinose. A future-oriented perspective on bioethanol production from pulp and paper industry wastes by the yeast P. tannophilus is considered.

CsINV5, a tea vacuolar invertase gene enhances cold tolerance in transgenic Arabidopsis

BackgroundVacuolar invertases (VINs) have been reported to regulate plant growth and development and respond to abiotic stresses such as drought and cold. With our best knowledge, the functions of VIN genes little have been reported in tea plant (Camellia sinensis L.). Therefore, it is necessary to develop research in this field.ResultsHere, we identified a VIN gene, CsINV5, which was induced by cold acclimation and sugar treatments in the tea plant. Histochemical assays results showed that the 1154 bp 5′-flanking sequence of CsINV5 drove β-glucuronidase (GUS) gene expression in roots, stems, leaves, flowers and siliques of transgenic Arabidopsis during different developmental stages. Moreover, promoter deletion analysis results revealed that an LTRE-related motif (CCGAAA) and a WBOXHVISO1 motif (TGACT) within the promoter region of CsINV5 were the core cis-elements in response to low temperature and sugar signaling, respectively. In addition, overexpression of CsINV5 in Arabidopsis promoted taproot and lateral root elongation through glucose-mediated effects on auxin signaling. Based on physiological and RNA-seq analysis, we found that overexpression of CsINV5 improved cold tolerance in transgenic Arabidopsis mainly by increasing the contents of glucose and fructose, the corresponding ratio of hexose to sucrose, and the transcription of osmotic-stress-related genes (P5CS1, P5CS2, AtLEA3, COR413-PM1 and COR15B) to adjust its osmotic potential.ConclusionsComprehensive experimental results suggest that overexpression of CsINV5 may enhance the cold tolerance of plant through the modification of cellular sugar compounds contents and osmotic regulation related pathways.

Exploring the potential of lactic acid production from lignocellulosic hydrolysates with various ratios of hexose versus pentose by Bacillus coagulans IPE22

The aim of this study was to investigate the feasibility of utilizing different lignocellulosic hydrolysates with various hexose versus pentose (H:P) ratios to produce lactic acid (LA) from Bacillus coagulans IPE22 by fermentations with single and mixed sugar. In single sugar utilization, glucose tended to promote LA production, and xylose preferred to enhance cell growth. In mixed sugar utilization, glucose and pentose were consumed simultaneously when glucose concentration was lower than 20 g/L, and almost the same concentration of LA (50 g/L) was obtained regardless of the differences of H:P values. Finally, LA production from corn cob hydrolysates (CCH) contained 60 g/L mixed sugar verified the mechanisms found in the fermentations with simulated sugar mixture. Comparing with single glucose utilization, CCH utilization was faster and the yield of LA was not significantly affected. Therefore, the great potential of producing LA with lignocellulosic materials by B. coagulans was proved.

Changes in carbohydrate levels and relative water content (RWC) to distinguish dormancy phases in sweet cherry

Perennial trees require chilling, i.e. a period of cold temperature in the winter, for flowering next spring; sweet cherry is particularly prone to lack of chilling. The objective of this study is to identify possible transition points to clearly distinguish dormancy phases by relating carbohydrate and relative water content (RWC) in reproductive buds to concomitant chilling fulfilment.This contribution proposes the use of four transition points between the dormancy phases and their characterization in terms of carbohydrates, water contents in combination with chilling values and may allow upscaling to other dormancy studies in trees; two groups of cherry varieties were defined based on their different initial sorbitol and starch level in the autumn. The first separation between para- and (deep) d-endo-dormancy is characterized as a transition from a decrease (variety group 1) or a constant level (variety group 2) to a sharp increase in hexoses and sorbitol and a drop of starch content. The second transition point (d-endo- to f-endo-dormancy) is characterized as the changes in both hexoses (increase) and starch (decrease) terminate and ca. 650 Chilling Hours (CH), i.e. insufficient chilling in the concomitant forcing experiment with cut branches. This third transition point (f-endo- to eco-dormancy) was characterized by ca. 1000 CH, the minimum chilling requirement and restrained flowering (cut branches). The fourth transition point (forcing initiation) marked an increase in water content at ca. 1550 CH, optimum chilling for cherry and coincided with natural flowering.A ratio of hexoses (glucose plus fructose) to starch content (<2:1) appeared to be a potential indicator of the beginning of chilling (para-dormancy) and a ratio of 14–20:1 typical for endo-dormancy, whereas the release from dormancy was associated with a decline to less than 10:1 at the end of winter (eco-dormancy).To our knowledge, this is the first time that transition points are identified based on constituents (carbohydrates and relative water content) in floral buds related to current chilling status and dormancy phases and are also presented in a schematic diagram. The understanding of these changes in relative water content and carbohydrate levels may contribute to manage insufficient chilling in the orchard and support climate change studies with trees.

Proposed descriptors for the evaluation of skin color, flesh firmness and juiciness, and sugar composition in Japanese persimmon breeding

Descriptors to evaluate fruit skin color, flesh firmness, flesh juiciness, and sugar composition using pollination constant non-astringent (PCNA)-type cultivars and selections of Japanese persimmon were proposed. A highly positive correlation was observed between the hue angle and color chart, and the skin color was classified as yellowish, hue angle ≥60°; orangish, hue angle between 51° and 59°; and reddish, hue angle ≤50°. Flesh firmness varied from 1.2 to 2.4 kg, and was classified as firm, ≥2.0 kg; medium, 1.4–1.9 kg; and soft, ≤1.3 kg. Flesh juiciness ranged from 0.18 to 0.39 mL g−1 FW, and was classified into very juicy, ≥0.30 mL g−1 FW; juicy, 0.21–0.29 mL g−1 FW; and slightly juicy, ≤0.20 mL g−1 FW. The analysis of variance for the flesh firmness, flesh juiciness, and sugar composition showed that the effect of genotype was large, while the effects of year, genotype × year interaction, among trees within genotype, and tree × year interaction were small or negligible. High varietal differences in sugar composition were found, ranging from 11.6 to 61.5% of the sucrose percentage. Furthermore, the sucrose to hexose (SH) ratio would be a useful descriptor for improving the palatability, especially sweetness, of PCNA-type persimmon fruits. The SH ratio ranged from 0.14 to 1.57, and was classified as very sweet, ≥1.00; sweet, 0.31–0.99; and less sweet, ≤0.30.

Promotion effect of sulfite on deoxyosones and 4-methylimidazole in caramel model system.

In this study, hydrogen-deuterium (H/D) exchange experiment was carried out to reveal the promotion effect of sulfite on the formation of deoxyosones and 4-methylimidazole (4-MeI) in the Maillard reaction. Glucose-ammonium (40mmol/L, pH 7.4 in PBS) model systems with different levels of sulfite were incubated at 110°C for 2h. Alpha-dicarbonyls were detected after derivatization by a high-performance liquid chromatography with a diode array detector (HPLC-DAD). 4-MeI in the Maillard reaction was tested using a high-performance anion exchange chromatography with an electrochemical detector (HPAEC-ED). The H/D exchange ratios of hexose (fructose, glucose and mannose) were tested by HPAEC-MS. Results showed that the aldo-enol transition of enediol was promoted by sulfite, which promoted the formation of deoxyosones and 4-MeI. In addition, the oxidation reaction of enediols was inhibited by the antioxidant sulfite, which caused the inhibition of osones formation in the Maillard reaction.

Identification of the invertase gene family (INVs) in tea plant and their expression analysis under abiotic stress.

Fourteen invertase genes were identified in the tea plant, all of which were shown to participate in regulating growth and development, as well as in responding to various abiotic stresses. Invertase (INV) can hydrolyze sucrose into glucose and fructose, which plays a principal role in regulating plant growth and development as well as the plants response to various abiotic and biotic stresses. However, currently, there is a lack of reported information, regarding the roles of INVs in either tea plant development or in the tea plants response to various stresses. In this study, 14 INV genes were identified from the transcriptome data of the tea plant (Camellia sinensis (L.) O. Kuntze), and named CsINV1-5 and CsINV7-15. Based on the results of a Blastx search and phylogenetic analysis, the CsINV genes could be clustered into 6 acid invertase (AI) genes and 8 alkaline/neutral invertase (A/N-Inv) genes. The results of tissue-specific expression analysis showed that the transcripts of all the identified CsINV genes are detectable in various tissues. Under various abiotic stress conditions, the expression patterns of the 14 CsINV genes were diverse in both the leaves and roots, and some of them were shown to be significantly expressed. Overall, we hypothesize that the identified CsINV genes all participate in regulating growth and development in the tea plant, and most likely through different signaling pathways that regulate the carbohydrate allocation and the ratio of hexose and sucrose for improving the resistance of the leaves and the roots of the tea plant to various abiotic stresses.

Norway spruce embryogenesis: changes in carbohydrate profile, structural development and response to polyethylene glycol.

Two unrelated, geographically distinct, highly embryogenic lines of Norway spruce (Picea abies (L.) Karst.) were analysed to identify metabolic traits characteristic for lines with good yields of high-quality embryos. The results were compared with corresponding characteristics of a poorly productive line (low embryo yield, scarce high-quality embryos). The following carbohydrate profiles and spectra during maturation, desiccation and germination were identified as promising characteristics for line evaluation: a gradual decrease in total soluble carbohydrates with an increasing sucrose : hexose ratio during maturation; accumulation of raffinose family oligosaccharides resulting from desiccation and their rapid degradation at the start of germination; and a decrease in sucrose, increase in hexoses and the appearance of pinitol with proceeding germination. We propose that any deviation from this profile in an embryonic line is a symptom of inferior somatic embryo development. We further propose that a fatty acid spectrum dominated by linoleic acid (18 : 2) was a common feature of healthy spruce somatic embryos, although it was quite different from zygotic embryos mainly containing oleic acid (18 : 1). The responses of the lines to osmotic stress were evaluated based on comparison of control (without osmoticum) and polyethylene glycol (PEG)-exposed (PEG 4000) variants. Although genetically distinct, both highly embryogenic lines responded in a very similar manner, with the only difference being sensitivity to high concentrations of PEG. At an optimum PEG concentration (3.75 and 5%), which was line specific, negative effects of PEG on embryo germination were compensated for by a higher maturation efficiency so that the application of PEG at an appropriate concentration improved the yield of healthy germinants per gram of initial embryonal mass and accelerated the process. Polyethylene glycol application, however, resulted in no improvement of the poorly productive line.

Modelling of Changes in Postharvest Quality Parameters of Stored Carrots Subjected to Pre- and Postharvest Treatments

Abstract The aim of this study was to develop qualitative models that enable prediction of quality of carrots. A full factorial experiment including preharvest biocatalyst application, dipping treatments and storage temperatures was employed. Eleven different biochemical and microbiological quality parameters of carrot (Daucus carota L.) were investigated. The effects of treatments on the shelf-life were investigated using discriminant analysis (DA). The lower storage temperatures (1°C) maintained the superior quality. Kinetic functions were applied to each parameter using the Levenberg–Marquardt algorithm to characterize the rate of change of quality. DAs significantly (P &lt; 0.001) differentiated between the combined effects of the preharvest biocatalyst treatment and storage temperatures. Four discriminant functions factored the differentiation of the quality attributes based on storage time. The models fit well to the experimental data for storage at 1°C. The second-order reaction equations allowed for prediction of ascorbic acid, sucrose and sugar–hexose ratio. First-order reaction equations that allow estimation of fructose, sucrose equivalent, total coliform and total fungi and O2 were developed. The empirical evidence suggests that freshness was maintained in the carrots until day 14 (P &lt; 0.001). Ascorbic acid, sucrose and sugar–hexose ratio were the most relevant parameters to rapidly detect the postharvest changes following the second-order decay rate.

Biology and management of sugarcane yellow leaf virus: an historical overview.

Sugarcane yellow leaf virus (SCYLV) is one of the most widespread viruses causing disease in sugarcane worldwide. The virus has been responsible for drastic economic losses in most sugarcane-growing regions and remains a major concern for sugarcane breeders. Infection with SCYLV results in intense yellowing of the midrib, which extends to the leaf blade, followed by tissue necrosis from the leaf tip towards the leaf base. Such symptomatic leaves are usually characterized by increased respiration, reduced photosynthesis, a change in the ratio of hexose to sucrose, and an increase in starch content. SCYLV infection affects carbon assimilation and metabolism in sugarcane, resulting in stunted plants in severe cases. SCYLV is mainly propagated by planting cuttings from infected stalks. Phylogenetic analysis has confirmed the worldwide distribution of at least eight SCYLV genotypes (BRA, CHN1, CHN3, CUB, HAW, IND, PER, and REU). Evidence of recombination has been found in the SCYLV genome, which contains potential recombination signals in ORF1/2 and ORF5. This shows that recombination plays an important role in the evolution of SCYLV.

Investigating the pollination syndrome of the Hawaiian lobeliad genus Clermontia (Campanulaceae) using floral nectar traits

Floral nectar sugar compositions have, for several decades, been used to predict a plant species' pollinator guild. Plants possessing a generalist ornithophilous pollination syndrome produce nectar that is dilute (8-12% w/v sugars) with a low sucrose to hexose (glucose and fructose) ratio. The Hawaiian lobeliad genus Clermontia contains 22 endemic species of shrubs and small trees that are believed to have evolved flowers adapted for pollination by now mostly extinct or endangered endemic passerines in the Drepanidinae and Mohoidae. We analyzed the nectar sugar compositions, concentration, and nectar standing crop of 23 taxa to test the assumption that Clermontia taxa have evolved floral traits in response to selection pressures from these avian pollinators. All Clermontia taxa produced nectar with sugar concentrations (mean: 9.2% w/v ± 1.8 SD) comparable to the nectar of other plant species with a generalized bird pollination system. Nectar sugars were overwhelmingly composed of hexoses in all taxa (mean sucrose/hexose ratio: 0.02 ± 0.02). Nectar standing crop volumes varied widely among taxa, ranging from 9.7 µL ± 7.1 to 430.5 µL ± 401.8 (mean volume: 177.8 ± 112.0). Collectively, the nectar traits indicate that Clermontia species possess a generalist passerine pollination syndrome.

Chemical and Immunochemical Characterization of Polysaccharides of Sasa Veitchii Leaves

A hot water extract of Sasa veitchii is a health-promoting food in general use. To analyze the structure and function of the polysaccharide fraction of the extract, a macromolecular fraction was obtained by dialysis (HMF) and two polysaccharide fractions (NPS and APS) were separated by DEAE-Sephadex chromatography. HMF strongly reacted with human sera and immunoglobulin preparations. All of the IgM, IgG, and IgA classes of antibodies were reacted with HMF. Comparing the reactivity of NPS and APS, NPS showed significantly stronger reactivity to the sera. From physicochemical analysis, their molecular weights are 20,000 and 8,000, respectively. Sugar analyses of the acid hydrolysates indicated rhamnose, arabinose, xylose, mannose, glucose, and galactose in the molar ratio of 1.0 : 2.3 : 1.5 : 3.8 : 0.6 : 5.3 for NPS and 1.0 : 3.0 : 2.6 : 0.8 : 6.3 : 3.0 for APS, and suggested major differences in the ratio of hexoses. APS also contained 2.6% galacturonic acid. Methylation analyses suggested that 1) both NPS and APS have a highly branched structure, 2) only NPS contains galactofuranose residue at the non-reducing terminal. Partial acid hydrolysis of HMF and subsequent dialysis recovered a high molecular weight fraction, but the resulting product had significantly low immunochemical reactivity. Considering the physicochemical and immunochemical analyses, the major epitope structure of NPS was suggested to be galactofuranose residues. Immunochemical reactivity of the polysaccharide is a key molecular mechanism for the health promoting activity of S. veitchii.

Impact of Exposure to High Concentrations of Fructose on Cell Surface Chemistry and Carbohydrate Metabolism

We evaluated the impact high concentrations of fructose have on cell antigenicity and metabolism in vitro. Antigen composition and sugar pools in MEF and bEND‐3 cells were monitored when they were grown in either fructose or glucose. Cell antigenicity was monitored by the expression of ABO blood group antigens. MEF cells cultured in fructose exhibited an increase in A antigen expression compared to glucose. High concentrations of fructose lead to higher concentrations of fructose‐6‐phosphate, which accelerates hexosamine biosynthesis. Metabolic evaluation of carbohydrate pools by mass spectrometry also supports this. While the free sugar pool is similar in MEF cells treated with either sugar, it was noted that the glycoprotein/glycolipid pool is quite different. Cells cultured in fructose posses a 2:1 ratio of hexoses: hexosamines, while cells in glucose contain only hexoses in this pool, showing an increase in hexosamine concentrations in presence of fructose. bEND‐3 cells in fructose and glucose contained similar expression of all antigens monitored as well as carbohydrate pools although less dramatic shifts were also evident. From these results we can observe that fructose does impact hexosamine biosynthesis and therefore, cell antigenicity and carbohydrate metabolism but there is no universal response. While hexosamine production is greatly increased in MEF, which reflects in an increase of A antigens, the effects on bEND‐3 cells were minor. Changes in cell characteristics such as growth rate and tissue function may stem from exposure to different carbohydrates as major energy source.

English

In pineapple fruits, sugar accumulation plays an important role in flavor characteristics, which varies according to the stage of fruit development. Metabolic changes in the contents of fructose, sucrose and glucose and reducing sugar related to the activities of soluble acid invertase (AI), neutral invertase (NI), sucrose synathase (SS) and sucrose-phosphate synthase (SPS) were studied in winter and summer pineapple fruits in this paper. Sucrose was significantly increased in most of the harvesting winter fruits which reached the peak of 64.87 mg&middot;g-1 FW at 130 days after anthesis, while hexose was mainly accumulated at the 90 day of the summer fruits in July. The ratio of hexose to sucrose was 5.92:0.73 from the winter fruit in February. Interestingly, the activities of SPS and SS synthetic direction of the harvested fruits in February were significantly higher than those in July, whereas the invertase activities were exactly opposite. NI activity showed a similar trend to AI, but the amount of NI activity was higher than AI in both months. Therefore, NI appears to be one of the vital enzymes in pineapple fruit development. Conclusively, the enzyme activities related to sugar play key roles in the eating of quality pineapple, which could be improved by cultivation in different seasons. So we can arbitrate different temperature to improve the quality of pineapple fruits according to market demand. &nbsp; Key words:&nbsp;Pineapple (Ananas comosus), different harvest seasons, sucrose, sucrose phosphate synthase, sucrose synthase.

Modelling genetic and environmental control of biomass partitioning at plant and phytomer level of sugarcane grown in controlled environments

Sucrose content has reached ceiling levels in several countries despite aggressive crossing and selection programmes aimed at improving this important trait for the sugarcane industry. Much of the recent research effort has been directed towards molecular means for improving sucrose content and while some breakthroughs have been made in the laboratory, no plants modified for this purpose have been grown successfully in the field. Sugarcane grown mainly for its sucrose in the past is now being considered for its fibre content as well because of increased interest in renewable energy. The paper offers an account of the variation in fibre, sucrose and hexoses in aboveground organs in relation to genotype, temperature and water regime with the aim of an improved understanding of biomass partitioning needed to effectively exploit sugarcane’s potential for multiple production streams. Previous studies often focused on single genotypes and on partitioning within stalks and ignored the effects of whole-plant structural partitioning on sugar accumulation. A mathematical model was constructed of biomass partitioning (at whole-plant and phytomer levels) of two high and two low sucrose clones of sugarcane from data collected in two controlled environment experiments, with water and temperature as treatments. The model tested the hypothesis that genetic differences in sucrose accumulation and responses to water and temperature can be explained by differences in plant development and partitioning to structural components such as leaf and stalk fibre. Whole-plant biomass partitioning between leaf, stalk structure and stored sugars was adequately simulated using clone-specific partitioning fractions modified by water status and temperature. Leaf partitioning fractions varied significantly between clones (low sucrose clones had high leaf fractions) but not between treatments. Stalk fibre partitioning fractions did not vary between clones but increased with improved water status and increased temperature. These aspects were mostly represented successfully in the model mainly because partitioning parameters were derived from the same data. Sugar accumulation was simulated, reasonably successfully, as the remainder of the biomass pool after partitioning to structural pools. Phyllochron intervals determined the rate at which phytomers ceased structural growth and commenced sugar accumulation. Low sucrose clones had longer intervals and so started sucrose accumulation later than high sucrose clones. There were also clonal differences in the ratio of hexose to sucrose (low sucrose clones had high ratios) and this could largely be explained by the structural mass fraction present in biomass. Although the data did not allow independent tests of all model assumptions, modelling these experiments did assist in gaining improved understanding of the underlying mechanisms of genetic and environmental control of biomass partitioning at whole-plant and phytomer levels. Results suggest that a way to enhance sucrose yields could be to breed genotypes with appropriate phenological and structural partitioning traits such as rapid phytomer development and low leaf partitioning fractions. This needs to be confirmed by further studies on more genotypes and environments.