Increasing Sucrose Concentration Research Articles

In vitro propagation and conservation of an endangered high value medicinal herb Swertia chirayita of temperate Himalayas

The current study reports on in vitro propagation and conservation of critically endangered medicinal plant Swertia chirayita. The sterilized explants (leaves) were cultured on Murashige and Skoog’s (MS) medium supplemented with 0.1 mg/L naphthalene acetic acid (NAA) and 3.0 mg/L benzyl adenine (BA) for callus induction, the same medium was used for shoot regeneration and for direct shoot regeneration from in vitro leaves. For in vitro multiplication shoots were cultured on MS medium supplemented with 2.5 mg/L benzyl adenine and 0.1 mg/L Kinetin (Kn). MS half strength medium supplemented with 400 mg/L activated charcoal and 0.1 mg/L naphthalene acetic acid showed 80.30% root induction from in vitro grown shoots. The in vitro raised plantlets were successfully acclimatized. All the regenerated plantlets appeared normal with 70–80% survival rate, while In vitro conservation was carried out by using two different approaches namely slow growth by changing media composition (sucrose and abscisic acid) at low temperature and cryopreservation following vitrification. With increase in concentration of sucrose and ABA decrease in growth of in vitro shoots was observed. At low temperature the in vitro shoots incubated at 4 and 10 °C both showed 100% retrieval. During studies the vitrified shoot gave retrieval of 42.33% when pre-cooled at 4 °C while only 22.77% vitrified shoots were retrieved from those pre-cooled at 10 °C.

Varietal performance of potato on induction and development of microtuber in response to sucrose

Tissue culture techniques are the most momentous and extensively method to produce disease-free quality plantlets and microtubers in potato. In spite of this, there has been a lack of research information into in vitro microtuberization for seed tuber production program in Bangladesh. In this experiment, we assessed the appropriateness of different concentrations of sucrose with especial accent on their effects for induction and development of microtuber in potato varieties. In vitro plantlets of three potato varieties; Asterix, Granola, and Diamant were treated with eight level of sucrose as 0, 3, 4, 6, 8, 10, 12 and 14% for 70days of incubation producing microtuber. Asterix induces microtuber after 10.69days, it was statistically shorter duration than other two varieties. Tuberization did not occur without sucrose and were required a minimum (8.92days) with 8% sucrose, while it delayed with either increasing or decreasing rate of sucrose concentration. A single number of microtuber was not formed in absence of sucrose after 28days of incubation. Microtuber plantlet−1 was the highest more or less in all varieties at harvest with 8% sucrose concentration. Hundred percent of microtuber below 250mg induced in 3% sucrose concentration and from then the microtuber grade induction decreased with the increase of sucrose concentration. >500mg grade microtuber produced by Granola (47.95%) with 10% sucrose while Diamant produced 50.15% above 500mg grade microtuber with 14% sucrose. It is also noticeable by Astrerix variety where >500mg microtuber were produced about 46.95% with 8% sucrose.

Effect of bacteria type and sucrose concentration on levan yield and its molecular weight

BackgroundLevan has been traditionally produced from microorganism. However, there is a continuous effort in looking for new strains that improve levan production yield and uses alternative sugar sources for growth. Despite having a wide range of data about levan yield, there are not papers which allow controlling molecular weight, and that plays an essential role for further applications.ResultsThe effect of the sucrose concentration on levan yield (and its molecular weight) from Bacillus atrophaeus and Acinetobacter nectaris (Gram positive and Gram negative respectively) was studied in this work. It was found that A. nectaris growth (from 3 to 1.5 g L−1 in 40 h) and its levan production (from 3 to 1.5 g L−1) decreases by increasing sucrose concentration (best results at a concentration of 120 g L−1) whereas B. atrophaeus growth (3.5 g L−1 in 30 h) and its levan production (also 3.5 g L−1) were not affected by modifying that parameter. Levan molecular weight from A. nectaris decreases by increasing sucrose concentration (from 8000 to 2000 kDa) whereas levan molecular weight from B. Atrophaeus remains always around 50 kDa. By performing a kinetic study, it was shown that A. nectaris growth follows a substrate-inhibition model, whereas Monod equation provided a good fit for B. atrophaeus growth. Finally, wastes from orange juice industry were used as a medium culture to cultivate those microorganism, obtaining good results with B. atrophaeus (growth 3 g L−1 in 30 h).ConclusionsLevan production kinetics was determined and compared between different bacteria types.

Reliable and practical methods for cryopreservation of embryogenic cultures and cold storage of somatic embryos of Norway spruce

Somatic embryogenesis (SE) is considered as the most-effective method for vegetative propagation of Norway spruce (Picea abies L. Karst). For mass propagation, a cryopreservation method able to handle large numbers of embryogenic tissues (ETs) reliably and at low costs is needed. The aim of the present study was to compare pretreatments, cryoprotectants and slow-cooling devices for cryopreservation of Norway spruce ETs, with 12 variations of methods and a total of 136 spruce genotypes. Secondly, possible applications for cold storage of mature somatic embryos were studied with the aim of developing a flexible time window for embling production. At best, 100% of the embryogenic lines were recovered following cryopreservation, but the results varied among the sets of lines. Also physiological condition of the tissues, pre-treatment and cryoprotectant applied, as well as the slow-cooling device used were found to affect the recovery. The best option for cryopreservation of Norway spruce is to select fresh growth from young ETs as samples, pretreat them on semi-solid medium with increasing sucrose concentration (0.1 M for 24 h; 0.2 M for another 24 h), apply a mixture of polyethylene glycol 6000, glucose, and dimethylsulfoxide, 10% w/v each, as cryoprotectant and use a programmable freezer with a slow cooling rate (0.17 °C/min). On average, 87% of the genotypes can be recovered, without any effect on their genetic fidelity, as shown by microsatellite markers and embryo production capacity. Mature somatic embryos of Norway spruce can also be safely cold-stored at +4 °C, without adverse effects on their germination ability.

Comparison of different drying methods on the chemical and sensory properties of chestnut (Castanea sativa M.) slices

The aim of this work was to determine the effect of hot-air convective drying (D), osmotic dehydration (OD), osmotic dehydration + drying (OD + D) and freeze-drying (FD) on chemical and sensorial characteristics of chestnut slices. Proximate composition, sugars, organic acids and lipid profiles were determined along 60 days of storage. Immediately after production, D and FD samples had similar proximate compositions, both with higher fat and protein contents than the osmodehydrated ones, the latter with increased sucrose contents. FD was the method that better preserved starch, amylose, ascorbic and citric acid molecules at day 0, while D originated samples with higher glucose and fructose contents. Along storage, the major variations were observed on organic acids: ascorbic acid decreased on all methods, while fumaric acid increased. Only small variations were observed on the fatty acids and vitamin E profiles and amounts. All samples presented similar and good overall sensorial acceptance with the exception of D. FD was the method that better preserved the sensorial characteristics until 60 days of storage, while D only preserved freshness until 15 days and OD + D until 30 days. In general terms, the most adequate and accepted preservation methods to apply to chestnuts would be FD and OD + D.

Influence of High Temperature on Sucrose Metabolism in Chalky and Translucent Rice Genotypes

Chalk is an unwanted and unpleasant opaque area in the rice grain caused by loosely packed starch granules possessing numerous air spaces. High temperature during grain filling favours induction of chalky grains; therefore, studying grain sink activity and carbon partitioning under these conditions would help to elucidate the difference in sucrose metabolism in chalky and translucent genotypes. Two rice genotypes viz., PAU-3699-13-2-1-1 (chalky) and PR122 (translucent) were sown at two different dates in order to expose the plants to different temperature regimes during grain filling. Significant increase in sucrose content, reduction in sucrose synthase (SuSy) and increased acid invertase (AIV) activity was observed during early transplanting (ET) when the crop encountered heat stress. Reduction in SuSy activity during ET did not allow cleavage of sucrose, thereby restricting the synthesis of starch. PAU-3699-13-2-1-1 exhibited higher acid invertase activity than PR122. The partially purified AIV exhibited optimum pH of 5.5 and 5.0 during ET, but 5.0 and 4.5 during normal transplanting (NT) in PAU-3699-13-2-1-1 and PR 122, respectively. The optimum temperature for AIV activity was 50 and 45 °C for the two genotypes during ET and NT, respectively. Changes in optimum pH, optimum temperature and Km of AIV during ET might be responsible for reduced accumulation of starch and increase in percent of chalky grains. Enhanced AIV activity may enable the grain carbon metabolism to adapt to high temperatures by providing hexoses for enhanced respiratory needs experienced during grain development.

Osmolytic Effect of Sucrose on Thermal Denaturation of Pea Seedling Copper Amine Oxidase.

Protein stability is a subject of interest by many researchers. One of the common methods to increase the protein stability is using the osmolytes. Many studies and theories analyzed and explained osmolytic effect by equilibrium thermodynamic while most proteins undergo an irreversible denaturation. In current study we investigated the effect of sucrose as an osmolyte on the thermal denaturation of pea seedlings amine oxidase by the enzyme activity, fluorescence spectroscopy, circular dichroism, and differential scanning calorimetry. All experiments are in agreement that pea seedlings amine oxidase denaturation is controlled kinetically and its kinetic stability is increased in presence of sucrose. Differential scanning calorimetry experiments at different scanning rates showed that pea seedlings amine oxidase unfolding obeys two-state irreversible model. Fitting the differential scanning calorimetry data to two-state irreversible model showed that unfolding enthalpy and T *, temperature at which rate constant equals unit per minute, are increased while activation energy is not affected by increase in sucrose concentration. We concluded that osmolytes decrease the molecular oscillation of irreversible proteins which leads to decline in unfolding rate constant.

Potassium fertilizer improves drought stress alleviation potential in cotton by enhancing photosynthesis and carbohydrate metabolism

Under drought, limited photo-assimilates synthesis and their poor partitioning is a main constraint to final yield production in cotton (Gossypium hirsutum L.). To study the potassium (K) role in photo-assimilation and carbohydrate metabolism in cotton under soil drought stress during flowering and boll formation stage, a two-year pot experiment was conducted in 2015 and 2016. Two cotton cultivars namely Simian 3 (low-K tolerant) and Siza 3 (low-K sensitive) were grown under three K rates (0, 150 and 300kgK2Oha−1). Plants were exposed to well-watered [(75±5%) soil relative water content (SRWC)] and water stress (35–40% SRWC) for 7days followed by re-watering to SRWC (75±5%). The results showed that water-stressed plants under K0 application exhibited significant decline in net photosynthesis, stomatal conductance, intercellular CO2 concentration and ribulose-1,5-bisphosphate carboxylase (Rubisco) activity and resulting in reduced photo-assimilates synthesis and partitioning towards reproductive organs in both cultivars. Conversely, K application decreased the decline in photosynthesis, Rubisco activity and biomass accumulation and partitioning. The positive effects of K application increased as increasing K rates, and that was more pronounced in Siza 3 than Simian 3. Drought stress decreased starch content but increased sucrose content; whereas, K application maintained higher concentration of sucrose in leaves of water-stressed plants through the regulation of higher sucrose phosphate synthase (SPS), sucrose synthase (SuSy) and lower soluble acid invertase (SAI) activities. The results of the study concluded that K application regulated the photo-assimilation and translocation process along with the related enzymes activities in cotton. The study suggests that K nutrient management strategy has the potential to minimize the impacts of drought stress in cotton.

Soluble Acid Invertase (SAI) Activity and Gene Expression Controlling Sugar Composition in Sugarcane

Enhancing cane and sugar productivity is the major concern of sugarcane growing countries. The present study was aimed to monitor the expression of SAI gene related to the sugar content during elongation phase and its modulation at the onset of cane ripening using an early maturing, high-sugar genotype (CoJ 64) and a mid-late maturing, low-sugar genotype (BO 91). The results indicated comparatively higher concentrations of non-reducing, total sugars and non-reducing/reducing sugar ratio (NRS/RS ratio) in CoJ 64 in all plant tissues (root, stalk and leaf); the highest was in stalk tissue. Similar to sugar content, Brix value (a field indicator of sucrose content) was also higher in CoJ 64. In contrast to this, reducing sugars content, SAI enzyme activity and gene expression level were relatively higher in BO 91. Root tissues showed higher SAI gene expression in BO 91 as compare to CoJ 64, indicating its utility as a molecular tool for characterizing high- and low-sugar genotypes at an early growth stage. Correlation data indicated a negative association of SAI activity and gene expression with non-reducing sugars and NRS/RS ratio, but positive with reducing sugars contents. Differential SAI expression in low- and high-sugar genotypes at the stage of crop elongation may help to manipulate sucrose accumulation process in low-sugar genotypes. In this domain, an effort was also made to improve sucrose content in cane stalk of BO 91 during inclined phase using enzyme effectors (Mg, Mn, B, Mg + Mn, ethrel and a mixture of Mg + Mn + ethrel as a chemical formulation). Chemical formulation was found to be more effective for increasing sucrose content with reduced SAI activity. Findings thus suggest downregulation of SAI activity in response to foliar application of chemical formulation vis-a-vis improvement in sucrose content might be due to significant negative association of SAI gene with non-reducing sugars (sucrose) in both low- and high-sugar genotypes.

Ectopic expression of TaOEP16-2-5B, a wheat plastid outer envelope protein gene, enhances heat and drought stress tolerance in transgenic Arabidopsis plants

Abiotic stresses, such as heat and drought, are major environmental factors restricting crop productivity and quality worldwide. A plastid outer envelope protein gene, TaOEP16-2, was identified from our previous transcriptome analysis [1,2]. In this study, the isolation and functional characterization of the TaOEP16-2 gene was reported. Three homoeologous sequences of TaOEP16-2 were isolated from hexaploid wheat, which were localized on the chromosomes 5A, 5B and 5D, respectively. These three homoeologues exhibited different expression patterns under heat stress conditions, TaOEP16-2-5B was the dominant one, and TaOEP16-2-5B was selected for further analysis. Compared with wild type (WT) plants, transgenic Arabidopsis plants overexpressing the TaOEP16-2-5B gene exhibited enhanced tolerance to heat stress, which was supported by improved survival rate, strengthened cell membrane stability and increased sucrose content. It was also found that TaOEP16-2 was induced by drought stress and involved in drought stress tolerance. TaOEP16-2-5B has the same function in ABA-controlled seed germination as AtOEP16-2. Our results suggest that TaOEP16-2-5B plays an important role in heat and drought stress tolerance, and could be utilized in transgenic breeding of wheat and other crop plants.

CAMBIOS EN PROPIEDADES MECÁNICAS DURANTE LA DESHIDRATACIÓN OSMÓTICA DE PITAHAYA AMARILLA

Fruits such as yellow pitahaya exhibit changes in their mechanical properties during osmotic dehydration (OD). The knowledge of these mechanical properties is useful for the analysis of the quality and/or stability of the food. There was evaluated the influence of the time of osmotic dehydration, the level of pressure (atmospheric pressure and vacuum pulse) and the sucrose concentration of the osmotic solution (SO) (45 and 65°Brix) on the mechanical properties of slices of pitahaya. The vacuum pulse was 5 kPa for 5 min. Fresh and dehydrated samples were subjected to uniaxial compression tests until rupture; Three mechanical parameters were evaluated (fracture stress, fracture strain and modulus of elasticity). The results showed that the fracture stress and modulus of elasticity decreased significantly with OD time and vacuum pulse application, while increasing with increasing sucrose concentration. The fracture strain was increased with the OD time and with the vacuum pulse. These results indicate that the yellow pitahaya retains more firmness with atmospheric pressure and with 65°Brix with respect to the treatments with application of the empty pulse.

Characterization of dextransucrase from Leuconostoc mesenteroides T3, water kefir grains isolate

The production of dextransucrase (DS) by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized. Bacterial supernatant reached activity of 3.1 U/ml when the culture was grown at 23 ?C and under static culture condition using classical Tsuchiya medium for DS production. The increase of sucrose concentration to 7% led to an increase of DS activity by 52% compared to the control. Medium with 2% beef extract and 1% yeast extract resulted in 4.52 U/ml, which was 47% higher than in the control (with 2% yeast extract). Finally, the increase of K2HPO4 concentration from 2 to 3% resulted in the increased enzyme activity by 28%. Enzyme purified by polyethylene glycol 400 fractionation displayed maximum activity at 30?C and pH 5.4. Zymogram analysis confirmed the presence of DS of approximately 180 kDa. The addition of divalent cations Ca2+, Mg2+, Fe2+ and Co2+ led to a minor increase of DS activity, while the addition of Mn2+ was the most prominent with 73% increase. These findings classify dextransucrase from Leuconostoc mesenteroides T3 as promising candidate for production of dextran, which has numerous applications in various industries.

Irrigated Sugarbeet Sucrose Content in Relation to Growing Season Climatic Conditions in the Northwest U.S.

The potential effects of changing climate on world food production have become a political and scientific focus. This study was conducted to investigate linkages between seasonal climatic conditions and sugarbeet sucrose content in southern Idaho and eastern Oregon. Sucrose content of irrigated sugarbeets delivered to 74 receiving stations in southern Idaho and eastern Oregon from 1997 through 2014, and daily climate data (growing degree days [GDD] and accumulated alfalfa reference crop evapotranspiration, maximum air temperature, minimum air temperature and mean air temperature, global solar radiation, accumulated growing degree days, and mean relative humidity) from regional weather stations were collected and analyzed using various regression techniques to investigate linkages between climate variables and sugarbeet sucrose content. Ninety-nine climatic parameters were analyzed with 34 having correlations with sugarbeet sucrose content > |0.3|. The most important climatic parameter related to mean sucrose content was early stage sugarbeet growth (late April to mid-May). In general, as temperature and GDD increased sucrose content decreased. Results indicate increases in both early season and mid-season temperatures will lead to decreases in sugarbeet sucrose concentrations. However, if sugarbeet root yields increase due to increasing temperatures and GDD accumulation, the sucrose yield changes would be buffered.

Melon fruit sugar and amino acid contents are affected by fruit setting method under protected cultivation

This study investigated the effect of different fruit setting methods on fruit quality of melon (Cucumis melo L.) under protected cultivation. The results showed that artificial and honey bee pollination decreased single fruit weight compared with 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) treatment, whereas the lowest value was observed in artificial pollination. Artificial and honey bee pollination apparently increased sucrose content, and the increased activity of sucrose phosphate synthase (SPS) was the key reason. In addition, total content of amino acids (17 kinds) were increased by 31% and 28% in artificial and honey bee-pollinated fruits compared with CPPU treatment, respectively. Honey bee pollination also improved single fruit weight and taste compared with artificial pollination. Therefore, we can conclude that artificial and honey bee pollination can improve the quality of melon fruits. In addition, honey bee can provide a better pollination service compared with artificial pollination for melons grown under protected cultivation systems.

PHYSIOLOGICAL RESPONSES TO HIGH EXOGENOUS SUCROSE IN TUBER INDUCTION OF POTATO IN VITRO

Microtubers are valuable tools to be used in the researches of potato. Among the factors sucrose is the most critical stimulus for potato microtuber production in vitro. The aim of our study was to define whether only sucrose was enough to induce the tuber and how it impacted on physiological responses in potato in vitro. Among sucrose concentrations chosen 80 and 100g/l sucrose could induce maximum tubers in three cultivars of Solanum tuberosum L., Atlantic, Desiree and 851 in vitro at 22 oC under 16-h photoperiod. Meanwhile tuber induction percentage showed no difference in MS with 80 and 100g/l sucrose among 0, 16 and 24-h photoperiod and cuttings with no nodes induced no tubers in cv. Atlantic. Therefore, 80 or 100g/l of exogenous sucrose concentrations and cuttings with node were essential to in vitro tuber induction in potato. The endogenous sucrose content and acid invertase in induced cuttings were higher than corresponding tubers and dramatically increased with the increase of sucrose concentration in MS. Starch content was completely opposite to endogenous sucrose content and decreased with the increase of sucrose concentration in MS. Sucrose synthase (Susy) and sucrose phosphate synthase (SPS) accumulated only in tubers, but no significant differences of Susy and SPS were between 80g/l and 100g/l sucrose. In conclusion, high levels of exogenous sucrose resulted in a dramatic high gradient of endogenous sucrose content between inducing cuttings and the corresponding tubers, which was beneficial to trigger differential activity expression of sugar metabolizing enzymes and to accumulate starch in tubers in vitro.

In vitro sucrose concentration influences microtuber production and diosgenin content in white yam (Dioscorea rotundata Poir)

Dioscorea spp. is an important food crop in many countries and the source of the phytochemical diosgenin. Efficient microtuber production could provide source materials for farm-planting stock, for food markets, and for the production of high-diosgenin-producing cultivars. The first step in this study was optimizing the plant growth regulators for plantlet production, followed by a study of the effects of sucrose concentration on microtuber induction and diosgenin production. Significantly, more shoots (3.5) were produced at 4.65 μM (1 mg L−1) kinetin (KIN), longer shoots (4.1 cm) were obtained at 2.46 μM (0.5 mg L−1) indole-3-butyric acid (IBA), and root number (3.9) was significantly higher at 5.38 μM (1 mg L−1) naphthalene acetic acid (NAA) than in other treatments. Increased sucrose concentrations in the optimized growth medium with 4.65 μM KIN and 5.38 μM NAA had significant effects on microtuber production (p < 0.01) and diosgenin content (p < 0.05). The most microtubers (6.2) were obtained with 100 g L−1 sucrose, while those on 80 g L−1 sucrose were the heaviest (0.7 g) and longest (7.4 mm). Microtubers formed in medium with 80 g L−1 sucrose had significantly higher diosgenin content (3.64% [w/w]) than those in other sucrose treatments (< 2%) and was similar to that of field-grown parent tubers (3.79%). This result indicates an important role for sucrose in both microtuber growth and diosgenin production. Medium containing 4.65 μM KIN and 5.38 μM NAA is recommended for plantlet production, and medium containing 80 g L−1 sucrose is recommended for microtuber and diosgenin production.

Biophysical characterization of the Lactobacillus delbrueckii subsp. bulgaricus membrane during cold and osmotic stress and its relevance for cryopreservation.

Freezing lactic acid bacteria often leads to cell death and loss of technological properties. Our objective was to provide an in-depth characterization of the biophysical properties of the Lactobacillus delbrueckii subsp. bulgaricus membrane in relation to its freeze resistance. Freezing was represented as a combination of cold and osmotic stress. This work investigated the relative incidence of increasing sucrose concentrations coupled or not with subzero temperatures without ice nucleation on the biological and biophysical responses of two strains with different membrane fatty acid compositions and freeze resistances. Following exposure of bacterial cells to the highest sucrose concentration, the sensitive strain exhibited a survival rate of less than 10% and 5h of acidifying activity loss. Similar biological activity losses were observed upon freeze-thawing and after osmotic treatment for each strain thus highlighting osmotic stress as the main source of cryoinjury. The direct measurement of membrane fluidity by fluorescence anisotropy was linked to membrane lipid organization characterized by FTIR spectroscopy. Both approaches made it possible to investigate the specific contributions of the membrane core and the bilayer external surface to cell degradation caused by cold and osmotic stress. Cold-induced membrane rigidification had no significant implication on bacterial freeze-thaw resistance. Interactions between extracellular sucrose and membrane phospholipid headgroups under osmotic stress were also observed. Such interactions were more evident in the sensitive strain and when increasing sucrose concentration, thus suggesting membrane permeabilization. The relevance of biophysical properties for elucidating mechanisms of cryoinjury and cryoprotection is discussed.

A new genomic library of melon introgression lines in a cantaloupe genetic background for dissecting desirable agronomical traits.

BackgroundGenomic libraries of introgression lines (ILs) consist of collections of homozygous lines with a single chromosomal introgression from a donor genotype in a common, usually elite, genetic background, representing the whole donor genome in the full collection. Currently, the only available melon IL collection was generated using Piel de sapo (var. inodorus) as the recurrent background. ILs are not available in genetic backgrounds representing other important market class cultivars, such as the cantalupensis. The recent availability of genomic tools in melon, such as SNP collections and genetic maps, facilitates the development of such mapping populations.ResultsWe have developed a new genomic library of introgression lines from the Japanese cv. Ginsen Makuwa (var. makuwa) into the French Charentais-type cv. Vedrantais (var. cantalupensis) genetic background. In order to speed up the breeding program, we applied medium-throughput SNP genotyping with Sequenom MassARRAY technology in early backcross generations and High Resolution Melting in the final steps. The phenotyping of the backcross generations and of the final set of 27 ILs (averaging 1.3 introgressions/plant and covering nearly 100 % of the donor genome), in three environments, allowed the detection of stable QTLs for flowering and fruit quality traits, including some that affect fruit size in chromosomes 6 and 11, others that change fruit shape in chromosomes 7 and 11, others that change flesh color in chromosomes 2, 8 and 9, and still others that increase sucrose content and delay climacteric behavior in chromosomes 5 and 10.ConclusionsA new melon IL collection in the Charentais genetic background has been developed. Genomic regions that consistently affect flowering and fruit quality traits have been identified, which demonstrates the suitability of this collection for dissecting complex traits in melon. Additionally, pre-breeding lines with new, commercially interesting phenotypes have been observed, including delayed climacteric ripening associated to higher sucrose levels, which is of great interest for Charentais cultivar breeding.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-016-0842-0) contains supplementary material, which is available to authorized users.

Sucrose-induced anthocyanin accumulation in vegetative tissue of Petunia plants requires anthocyanin regulatory transcription factors

The effects of three different sucrose concentrations on plant growth and anthocyanin accumulation were examined in non-transgenic (NT) and transgenic (T2) specimens of the Petunia hybrida cultivar ‘Mirage rose’ that carried the anthocyanin regulatory transcription factors B-Peru+mPAP1 or RsMYB1. Anthocyanin accumulation was not observed in NT plants in any treatments, whereas a range of anthocyanin accumulation was observed in transgenic plants. The anthocyanin content detected in transgenic plants expressing the anthocyanin regulatory transcription factors (B-Peru+mPAP1 or RsMYB1) was higher than that in NT plants. In addition, increasing sucrose concentration strongly enhanced anthocyanin content as shown by quantitative real-time polymerase chain reaction (qRT-PCR) analysis, wherein increased concentrations of sucrose enhanced transcript levels of the transcription factors that are responsible for the induction of biosynthetic genes involved in anthocyanin synthesis; this pattern was not observed in NT plants. In addition, sucrose affected plant growth, although the effects were different between NT and transgenic plants. Taken together, the application of sucrose could enhance anthocyanin production in vegetative tissue of transgenic Petunia carrying anthocyanin regulatory transcription factors, and this study provides insights about interactive effects of sucrose and transcription factors in anthocyanin biosynthesis in the transgenic plant.

Functional Relationship between Sucrose and a Cariogenic Biofilm Formation.

Sucrose is an important dietary factor in cariogenic biofilm formation and subsequent initiation of dental caries. This study investigated the functional relationships between sucrose concentration and Streptococcus mutans adherence and biofilm formation. Changes in morphological characteristics of the biofilms with increasing sucrose concentration were also evaluated. S. mutans biofilms were formed on saliva-coated hydroxyapatite discs in culture medium containing 0, 0.05, 0.1, 0.5, 1, 2, 5, 10, 20, or 40% (w/v) sucrose. The adherence (in 4-hour biofilms) and biofilm composition (in 46-hour biofilms) of the biofilms were analyzed using microbiological, biochemical, laser scanning confocal fluorescence microscopic, and scanning electron microscopic methods. To determine the relationships, 2nd order polynomial curve fitting was performed. In this study, the influence of sucrose on bacterial adhesion, biofilm composition (dry weight, bacterial counts, and water-insoluble extracellular polysaccharide (EPS) content), and acidogenicity followed a 2nd order polynomial curve with concentration dependence, and the maximum effective concentrations (MECs) of sucrose ranged from 0.45 to 2.4%. The bacterial and EPS bio-volume and thickness in the biofilms also gradually increased and then decreased as sucrose concentration increased. Furthermore, the size and shape of the micro-colonies of the biofilms depended on the sucrose concentration. Around the MECs, the micro-colonies were bigger and more homogeneous than those at 0 and 40%, and were surrounded by enough EPSs to support their structure. These results suggest that the relationship between sucrose concentration and cariogenic biofilm formation in the oral cavity could be described by a functional relationship.