SPS Activity Research Articles

The Combined Application of Urea and Fulvic Acid Regulates Apple Tree Carbon and Nitrogen Metabolism and Improves Anthocyanin Biosynthesis

Improving apple peel color has been an important objective in apple production. To better understand the effect and mechanism of the combined application of urea and FA (fulvic acid) regulation of anthocyanin biosynthesis, a field experiment was performed in 2022 and 2023, respectively, under five treatments of urea + FA (CK, urea only; FA50, urea + 50 kg ha−1 FA; FA100, urea + 100 kg ha−1 FA; FA150, urea + 150 kg ha−1 FA; FA200, urea + 200 kg ha−1 FA), using isotope (13C and 15N) marking to analyze the changes in carbon (C) and nitrogen (N) nutrient distribution as well as anthocyanin biosynthesis in fruits. We observed that, under FA application conditions, anthocyanin content in the peel was elevated in both years, with increases of 15.98~52.88% in 2022 and 15.93~52.94% in 2023. The best promotion effects were observed under FA150 treatment. Apart from the expression levels of anthocyanin biosynthesis-related genes and transcription factors in the apple peel, this positive effect on anthocyanin content induced by FA addition was also found to be associated with the optimization of C and N distribution in leaves and fruits. On the one hand, the application of FA not only enhanced leaf photosynthetic-related indexes (such as Pn, Gs, and Rubisco activity) and influenced (increased) S6PDH, SPS, and SS activities in leaves, but also elevated fruit sugar metabolism-related enzyme (SDH, SS-c, AI, and NI) activity and upregulated fruit stalk sugar transporter (MdSOT1, MdSOT3, MdSUT1 and MdSUT4) gene expression, which ultimately promoted the synthesis and the leaf to fruit transport of photosynthates, thus promoting 13C-photosynthate accumulation in fruits. On the other hand, FA application elevated leaves’ N metabolism-related enzyme (GS and GOGAT) activity and optimized 15N distribution in leaves and fruits. Moreover, we also observed that FA application altered the fate of N fertilizer in apple orchards, showed an elevation in apple tree 15NUE and soil 15N residuals and showed a decrease in soil 15N loss. In summary, the appropriate application of FA150 (urea + 150 kg ha−1) synergistically optimized C and N nutrient distribution, and promoted anthocyanin biosynthesis in apple trees.

A novel growth-promoting dark septate endophytic fungus improved drought tolerance in blueberries by modulating phytohormones and non-structural carbohydrates.

Drought is a significant global issue affecting agricultural production, and the utilization of beneficial rhizosphere microorganisms is one of the effective ways to increase the productivity of crops and forest under drought. In this study, we characterized a novel growth-promoting dark septate endophytes (DSE) fungus R16 derived from the blueberry roots. Hyphae or microsclerotia were visible within the epidermal or cortical cells of R16-colonized blueberry roots, which was consistent with the typical characteristics of DSE fungi. Inoculation with R16 promoted the growth of blueberry seedlings and the advantage over the control group was more significant under PEG-induced drought. Comparison of physiological indicators related to drought resistance between the inoculated and control groups was performed on the potted blueberry plants, including the chlorophyll content, net photosynthetic rate, root activities, MDA and H2O2 content, which indicated that R16 colonization mitigated drought injury in blueberry plants. We further analyzed the effects of R16 on phytohormones and non-structural carbohydrates (NSCs) to explore the mechanism of increased drought tolerance by R16 in blueberry seedlings. The results showed that except for the GA content, IAA, ZT and ABA varied significantly between the inoculated and control groups. SPS and S6PDH activities in mature leaves, the key enzymes responsible for sucrose and sorbitol synthesis, respectively, as well as SDH, SuSy, CWINV, HXK and FRK in roots, the key enzymes involved in the NSCs metabolism, showed significant differences between the inoculated and control groups before and after drought treatment. These results suggested that the positive effects of R16 colonization on the drought tolerance of blueberry seedlings are partially attributable to the regulation of phytohormone and sugar metabolism. This study provided valuable information for the research on the interaction between DSE fungi and host plants as well as the application of DSE preparations in agriculture.

Expression of sucrose metabolizing enzymes in different sugarcane varieties under progressive heat stress.

Studying the thermal stress effect on sucrose-metabolizing enzymes in sugarcane is of great importance for understanding acclimation to thermal stress. In this study, two varieties, S2003-US-633 and SPF-238, were grown at three different temperatures ( ± 2°C): 30°C as a control, 45°C for various episodes of high temperature treatments and recovery conditions at 24, 48 and 72 hours. Data showed that reducing sugar content increased until the grand growth stage but sharply declined at the maturity stage in both cultivars. On the other hand, sucrose is enhanced only at the maturity stage. The expression of all invertase isozymes declined prominently; however, the expression of SPS was high at the maturity stage. Hence, the sucrose accumulation in mature cane was due to increased SPS activity while decreased invertase isozymes (vacuolar, cytoplasmic and cell wall) activities at maturity stage in both cultivars. Heat shock decreased the sucrose metabolizing enzymes, sucrose content and sugar recovery rate in both cultivars. In contrast, heat-shock treatments induced maximum proline, MDA, H2O2 and EC in both cultivars. Notably, this is the first report of diverse invertase isozyme molecular weight proteins, such as those with 67, 134 and 160 kDa, produced under heat stress, suggesting that these enzymes have varied activities at different developmental stages. Overall, S2003-US-633 performs better than the cultivar SPF-238 under heat stress conditions at all development stages, with increased sucrose content, enzyme expression, proline and sugar recovery rate. This work will provide a new avenue regarding sugarcane molecular breeding programs with respect to thermal stress.

The Responses of Sucrose Metabolism and Carbon Translocation in Tomato Seedlings under Different Light Spectra.

Light plays a dominant role in the biosynthesis and accumulation of photosynthetic products. However, the metabolism and translocation of photosynthetic products in plants under different light spectra remain elusive. In this study, tomato (Solanum lycopersicum L.) seedlings were treated with different light spectra delivered by light-emitting diodes (LEDs) with the same photosynthetic photon flux density at 300 μmol m-2 s-1, including monochromatic red (660 nm, R), blue (450 nm, B), sun-like white (W, 380-780 nm), or a combination of R and B lights (R:B = 1:1, RB). Compared with W, the biomass distribution ratio for leaves under R, B, and RB decreased by 5.01-9.53%, while the ratio for stems and roots increased by 3.71-6.92% and 0.14-2.81%, respectively. The photosynthetic carbon distribution expressed as 13C enrichment was higher in stems and roots under RB and R, while B led to more 13C transported from leaves and enriched in stems when compared with W. Meanwhile, RB led to significant increases in the activities of phosphate synthase (SPS), sucrose synthase (SS), vacuolar acid invertase (VI), and neutral invertase (NI). The R was more efficient in increasing the activity of SPS and SS, while B was more effective in promoting the activity of VI and NI. The transcript levels of SPS, SS3, NI6, and VI were upregulated under R, B, and RB. However, the transcript patterns of SPS, SS3, NI6, and VI were not consistent with the changes in their encoded enzymes, especially the transcript patterns of SPS and SS3. Our study suggests that the red- and blue-light-induced long-distance and short-distance transport of photosynthetic products in plants, respectively, might result from different regulation of sucrose-metabolizing enzymes from transcriptional and post-transcriptional levels.

Expression of a truncated maize SPS increases source capacity in maize

AbstractIn an attempt to increase source capacity, transgenic corn was generated by expressing a truncated maize sucrose phosphate synthase (ZmSPSΔ482) under two leaf mesophyll cellspecific promoters (CAB and PPDK). The endogenous and truncated SPS proteins from transgenic leaf extracts were distinguishable by protein immunoblot analysis. The expression of transgenic SPS protein across events varied from very low to very high and included several cosuppressed events. SPS activity showed a diurnal pattern in both transgenic and wild-type maize leaves. In greenhouse experiments, transgenic maize had higher leaf sucrose and lower leaf starch, suggesting a shift in carbon partitioning from starch to sucrose. Conversely, cosuppressed events had lower leaf sucrose and higher leaf starch. A field test was performed to compare sucrose and starch in positive and negative isolines of hybrid maize CAB and PPDK ZmSPSΔ482 events. In the field, many positive isolines had higher levels of both leaf sucrose and starch than the negative isolines. This suggests that in the field, with higher light intensity the shift in carbon partitioning from starch to sucrose, observed under greenhouse conditions did not occur. This in turn suggests that the environment affects the phenotype of the transgenics and that in the field, there was an overall increase in carbon assimilation. Six events from each construct were tested in a pilot multi-density yield trial but overall, no effect on yield was observed. Therefore, although the transgenic plants had more source capacity, this did not translate into higher seed yield.

Light Intensity Affects the Assimilation Rate and Carbohydrates Partitioning in Spinach Grown in a Controlled Environment.

The cultivation of spinach (Spinacia oleracea L.) has been increasing during the last years in controlled environment agriculture, where light represents a key factor for controlling plant growth and development and the highest energetic costs. The aim of the experiment was to evaluate the plant's response to two light intensities, corresponding to an optimal and a reduced level, in terms of the photosynthetic process, photoassimilates partitioning, and the biosynthesis of sucrose and starch. Plants of spinach cv. 'Gigante d'Inverno' were grown in a phytotron under controlled conditions, comparing two values of photosynthetic photon flux density (PPFD), 800 μmol m-2 s-1 (800 PPFD) and 200 μmol m-2 s-1 (200 PPFD), at a 10 h light/14 h dark regime. Compared to 800 PPFD, under 200 PPFD, plants showed a reduction in biomass accumulation and a redirection of photoassimilates to leaves, determining a leaf expansion to optimize the light interception, without changes in the photosynthetic process. A shift in carbon partitioning favouring the synthesis of starch, causing an increase in the starch/sucrose ratio at the end of light period, occurred in low-light leaves. The activity of enzymes cFBAse, SPS, and AGPase, involved in the synthesis of sucrose and starch in leaves, decreased under lower light intensity, explaining the rate of accumulation of photoassimilates.

Combined effect of elevated temperature and drought stress on carbohydrate metabolism of cotton (Gossypium hirsutum L.) subtending leaves.

High temperatures and drought are expected to become more frequent in the future and last longer than ever before. To investigate their combined effect on cotton subtending leaves (LSCB), an experiment was conducted from 2016 to 2018 using a non-heat-tolerant cotton cultivar and a heat-tolerant cultivar. Two temperature regimes with ambient temperature (AT, 31.0/26.4 °C) and elevated temperature (ET, 33.4/28.9 °C, 2.5 °C higher than AT) and three drought treatments with a soil relative water content (SRWC) of 75 ± 5%, 60 ± 5%, and 45 ± 5% were established repeatedly. ET decreased Pn, initial rubisco activity (4.1.1.39, RuBP) and cy-FBPase (3.1.3.11) activity, upregulated GhSuSyA, and GhSuSyD expressions, and increased SuSy (2.4.1.13) activity, which led to the decline of the final starch and sucrose contents. Moreover, RuBP, Pn, and starch content all decreased with drop in SRWC levels, but the cy-FBPase and SPS (2.4.1.14) activity increased, which in turn increased sucrose content. Under combined stresses, when the changing trends of ET and drought effects were the same, the decrease of Pn, RuBP, and starch content was greater than under single stress exposure. However, when the changing trends of ET and drought effects were adverse, the combined effects on indicators such as cy-FBPase, SuSy, sucrose content were mostly similar to drought stress. These results indicate that the effect of drought on carbohydrate metabolism in LSCB is more prominent than ET. Thus, the drought effect for carbohydrate metabolism in LSCB may need more attention than ET under combined heat and drought stress. This article is protected by copyright. All rights reserved.

Exogenous melatonin maintains postharvest quality in kiwiberry fruit by regulating sugar metabolism during cold storage

Melatonin plays a potential role in preserving the postharvest quality of fresh products. This study investigated the effect of exogenous melatonin on sugar metabolism and quality change in kiwiberries under cold storage. Our results showed that melatonin improved fruit appearance, increased total chlorophyll, carotenoid, and ascorbate accumulation, and inhibited firmness and weight loss during storage. In addition, melatonin treatment increased the ratio of fruit-soluble solids to acid and upregulated the content of sucrose, glucose, fructose, and soluble sugars by regulating the activities of SS, SPS, AI, and NI enzymes as well as their transcript levels. Melatonin application inhibited the activity of AL and upregulated the transcript levels of HK and FK genes to slow down the starch decomposition, thereby delaying the softening of kiwiberries during the storage. These results indicated that melatonin application after the harvest of kiwiberry could improve both the external and internal quality of the fruit and inhibit senescence by modulating sugar metabolism.

Effects of bearing branch leaves on sugar accumulation, SPS activity and gene expression in Satsuma mandarin ‘Okitsu wase’

Effects of bearing branch leaves on sugar accumulation, SPS activity and gene expression in Satsuma mandarin ‘Okitsu wase’

Low nitrogen level improves low-light tolerance in tall fescue by regulating carbon and nitrogen metabolism

Low-light (LL) stress is a primary factor contributing to turf deterioration. Previous studies have recommended the use of reduced nitrogen (N) fertility for maintaining turf grasses and improving their LL tolerance. However, the mechanism for turf grass susceptibility to LL-induced stress is still unclear. The present study investigated the role of low N in improving tall fescue photosynthesis under LL stress by regulating carbon and N metabolism. The LL stress significantly reduced tiller numbers, biomass, chlorophyll content, net photosynthetic rate ( Pn ), the maximum quantum yield of photosystem photochemistry ( Fv/Fm ), actual photochemical efficiency of photosystem II ( Φ PSII ), and the carbon and N contents in roots and leaves. The stress also reduced the sugars contents but increased the C/N ratio in the roots and leaves. However, low N alleviated the effects of LL stress by significantly increasing the tiller numbers, root length, root-to-shoot ratio, and sugars contents in roots. Under low light and low nitrogen (40 μmol m −2 s −1 PPFD + 1.0 mM N, LN-) conditions, the tiller number, Pn , soluble sugar content and protein content in the roots increased by 24.72%, 19.43%, 71.91%, and 16.05%, respectively, compared to the low light and normal nitrogen (40 μmol m −2 s −1 PPFD + 6.0 mM N, LN) conditions. Additionally, the activities of sucrose synthase (SS), glutamate dehydrogenase (GDH), and total amylase (AMY) in leaves and the activity of glutamate synthase (GOGAT) in roots were also remarkably enhanced by the low N level. Subsequently, a total of 514 metabolites were detected by non-targeted metabolomics analysis. There were 83 and 173 differential metabolites in the LL stress and control leaves and roots, respectively. Meanwhile, 54 and 67 differential metabolites were also detected in the leaves and roots under LN treatment and LN- treatment, respectively. The KEGG analysis showed that the LN- treatment significantly affected carbon and amino acid metabolism in tall fescue. Conversely, organic acids, amino acids, nucleic acids, and their respective derivatives were reduced in response to LL-induced stress. Furthermore, the LN- treatment enhanced the citrate cycle and increased the glucose and sucrose contents compared to the LN treatment. In addition, the asparagine level was significantly reduced in the leaves but significantly increased in the roots under LN- treatment. Thus, these results indicated that low N level increases photosynthesis by regulating the balance between carbon and N metabolism in the roots and leaves, thereby improving tolerance to LL-induced stress. • Low N improved activities of SPS, SS, GOGAT and GDH in tall fescue. • Low N up-regulated sugars, organic acids and amino acids in leaves. • Low N down-regulated sugars and amino acids in roots, but increased sucrose and Asn. • Low N increased contents of Asn in roots and Chl. • Low N regulated carbon and N metabolism, increased photosynthesis to improve LL tolerance.

Characterization of Soluble Sugar Content, Related Enzyme Activity and Gene Expression in the Fruits of ‘Minihyang’ Mandarin on Different Rootstocks

‘Minihyang’ mandarin bears fruits with small size and high sugar content. ‘Minihyang’ mandarin grafted on trifoliate orange (TO) tends to be vigorous and develops water sprout open. It is associated with insufficient floral differentiation and fruit set. Recently, the use of Flying Dragon (FD) as rootstock with a high dwarf effect has been proposed to improve this situation. Therefore, this study was conducted to evaluate the effect of two different rootstock genotypes on tree growth, fruit yield, and fruit quality at the physiological, biochemical, and molecular levels. As a result of the study, in FD, tree vigor was stably maintained, fruit size was large, and the sugar content was high compared to the TO. Fructose, glucose, and sucrose of fruit continued to increase from development to maturity. In particular, fructose and sucrose were significantly higher in the fruits of the FD than those in TO at 150 and 220 days after anthesis. The total sugar content was also significantly higher in the fruit of the FD. The activities of SPS and SS associated with sucrose synthesis tended to be increased during the fruit maturity season, but there was no significant difference between the two rootstocks. On the other hand, the activities of SS and AI breaking down sucrose were high in FD at 150 and 220 days after anthesis. These results suggest that the unloading of sucrose might be increased and affect the sugar content. However, the results of real-time PCR analysis of gene expression related to sucrose metabolism did not show an association with changes in enzyme activity affecting sugar content. Therefore, further detailed studies on the process after the regulation of gene expression are likely to be needed.

Identification, characterisation, and expression profile analysis of the sucrose phosphate synthase gene family in pineapple (Ananas comosus)

ABSTRACT Sucrose plays a crucial role in plant growth and development. Sucrose phosphate synthase (SPS, EC 2.4.1.14) is a key rate-limiting enzyme in the sucrose metabolism of plants. To date, the genome-wide identification, characterisation, and expression profile analysis of SPS gene families have been reported in many species but not in pineapple (Ananas comosus). In this study, five SPS genes (AcSPS1–5), which contained sucrose synthase, glucosyltransferase, and SPP-like conserved domains, were identified. The phylogenetic tree indicated that these AcSPS genes were divided into three clades, i.e. A, B, and C. The spatiotemporal expression pattern of AcSPS gene families were first examined in pineapple. Among all tissues, AcSPS2 had the highest expression in flesh. Meanwhile, AcSPS2 expression was significantly upregulated during fruit development. Furthermore, AcSPS2 expression, SPS activity, and sucrose content consistently increased with fruit development. These results may indicate that AcSPS2 played a major role in sucrose metabolism during fruit development. AcSPS5 was strongly expressed in the peduncle, pericarp, and core. On the basis of its abundant expression, AcSPS5 was speculated to play an important role in plant growth.

The physiological and proteomic characteristics of oilseed rape stem affect seed yield and lodging resistance under different planting densities and row spacing

AbstractLodging is an important factor that restricts the yield of rapeseed and the mechanical harvesting. To explore agricultural practise and mechanisms that can synergistically improve the rapeseed yield and lodging resistance, a conventional plant type HZ 62 was selected in 2016–2017, and HZ 62 and an erect‐leaf type 1,301 were grown in 2017–2018. The planting density was set as main plots at 15 × 104 plants ha1 (D1), 30 × 104 plants ha‐1 (D2) and 45 × 104 plants ha−1 (D3), with the row spacing as sub‐plots of 15 cm (R15), 25 cm (R25) and 35 cm (R35). The results showed that with increased density and narrowed row spacing, the radiation utilisation efficiency (RUE) of the population and seed yield were greatly increased. Compared with that at D1R25, the yield of HZ 62 at D3R15 was increased by 19.00% and 22.53%, respectively, in 2016–2017 and 2017–2018, whereas the yield of 1,301 rose by 31.98%. The influence of the RUE on the seed yield reached the peak at flowering stage. With increased planting density and narrowed row spacing, the lodging index of HZ 62 declined. The lodging index of 1,301 was increased with higher density and declined with narrowed row spacing. Compared with D1R25, the averaged lodging index across different parts of HZ 62 at D3R15 declined by 15.03% and 10.80%, respectively, in 2016–2017 and 2017–2018, and that of 1,301 was increased by 25.47%. Compared with D1R25, the stem proteomics during the flowering stage showed the expression of photosynthesis‐related proteins (A0A078FHG9, A0A078JZM9 and A0A078JQI2) up‐regulated, that consistent with Rubisco, SPS and FBPase activities; proteins related to phenylpropanes metabolism, A0A078IWR4 of HZ 62 and A0A078JWZ9 of 1,301 increased that consistent with POD activity, which resulted in more sucrose, starch and lignin in the stem at D3R15. Moreover, the protein related to cellulose synthesis (A0A078I4D9), the activity of β‐1,3‐glucanase and content of cellulose in the stem were up‐regulated in HZ 62 but down‐regulated in 1,301, contrary to the variation in the stem lodging index. The cellulose synthesis differed between the varieties in different treatment combinations of planting density and row spacing. This was the key process by which planting density and row spacing influence the lodging of rapeseed varieties with varied plant architecture.

High Temperature Stress Causes Transient Change in the Photosynthetic Machinery and Sucrose Metabolism of Sugarcane (Saccharum spp.)

Temperature extremes are among the major abiotic stresses affecting sugarcane yield and quality. High temperature stress in selected sugarcane clones reduced the total chlorophyll content, SPAD chlorophyll index and photosynthetic efficiency based on fluorescence parameters (Fv/Fm) by 18, 20 and 10% respectively, compared to ambient temperature grown plants. Such transient changes to the photosynthetic machinery caused 30, 15 and 20% reduction in photosynthetic rate, stomatal conductance and intercellular CO concentration respectively, over control. Significant reduction in SPS and SS enzyme activity was noticed due to long term exposure to elevated temperature treatment particularly in sensitive varieties (Co 8021 and Co 0315). Overall, the variation among traits for photosynthetic efficiency based on fluorescence parameters, SPAD chlorophyll index and transpiration rate was significant only under elevated temperature which indicates the effectiveness of using these traits to screen for thermotolerance.

Construction of optimum number of fruiting nodes benefit high yield in cotton population

High yield is the most important goal for cotton growers, but widely application of previous reported agronomic practices was difficult due to variations of locations, climate, and cropping system in Yangtze River area. It is desirable to find an universal index to indicate canopy structure and photosynthetic production states for high yield. Field studies with different planting densities, sown dates and nitrogen rates were conducted to detect the relationship between lint yield and number of fruiting nodes per hectare (FNN) during 2016 and 2017 cotton growth seasons. Across different cultivars and cultivation practices including sown dates, nitrogen rates, and planting density, the FNN was comparatively stable under highest yield, indicating the optimum FNN (290−320×104 nodes/ha) would benefit high yield formation. In 2018 and 2019, three FNN cotton populations (low, optimum and high) constructed by three nitrogen rates were designed to assess the canopy structure, photosynthetic production and final yield. The results showed that there were moderate plant height (conventional cultivar Sikang1: 101.7 cm–103.5 cm, hybrid cultivar Sikang3: 109.5 cm–110.1 cm), length of fruiting branch, bigger space for individual fruiting node, uniform vertical distribution of LA (the leaf area) and light intensity in cotton plants under optimum FNN. In addition, high leaf SPAD, highest leaf Fv/Fm, activities of SuSy, SPS, and SAI, uniform vertical distribution of dry matter and high ratio of dry matter accumulation in reproductive organs in cotton plants were found under optimum FNN condition. These results suggested that appropriate plant type and canopy structure could be constructed by building optimum FNN, and optimum FNN would promote photosynthetic capacity and dry matter accumulation in reproductive organs, and ultimately benefit the final yield. In addition, due to the comparatively stable FNN in high-yield cotton production across different cultivation practices and locations, FNN would be an key index to build high-yield cotton population.

Fluoride Stress-Mediated Regulation of Tricarboxylic Acid Cycle and Sugar Metabolism in Rice Seedlings in Absence and Presence of Exogenous Calcium

The aim of the current study was to investigate the regulation of tricarboxylic acid (TCA) cycle and sugar metabolism in the seedlings of the rice variety, Khitish, during fluoride stress, either in absence or presence of exogenous calcium compounds, viz., calcium hydroxide and calcium nitrate. The inhibitory effect of fluoride stress on energy production was reflected by lowered levels of pyruvic acid, citric acid and malic acid, substantial interference with the respiratory enzymes such as PDH, CS, IDH and SDH, and inhibiting the expression of the concerned genes. Seed priming with both calcium compounds elevated the organic acid levels, restored the activity of the above enzymes and expression of the corresponding genes. On the contrary, the enhanced fumarase and MDH activity and MDH gene expression, during fluoride stress, was lowered by calcium pre-treatment. The sucrose level, together with SPS and SS activity and expression of the corresponding genes were restored to higher levels, concomitant with lowered INV activity and gene expression, in presence of calcium compounds, suggesting lesser utilization of sucrose to combat fluoride stress. The efficacy of calcium compounds in conserving starch as the major food reserve, without provoking its catabolic breakdown, was established on the basis of enhanced starch content with lowered α-amylase and starch phosphorylase activity and corresponding gene expression. The present communication for the first time documented the detrimental impact of fluoride stress on TCA cycle metabolites and majority of the enzymes, and endogenous sucrose and starch accumulation, as well as highlighted the reversal of the negative effects with the exogenous application of calcium compounds.

Wheat NILs contrasting in grain size show different expansin expression, carbohydrate and nitrogen metabolism that are correlated with grain yield

Two wheat near-isogenic lines (NILs; -GS (small grain size) and + GS (large grain size)) were obtained by backcrossing. We found that the grain volume and weight of + GS were significantly higher than those of -GS. There was a corresponding increase in grain yield associated with the + GS line. For analysis of causes, we investigated and compared the anatomic and physiological characteristics of two NILs during the grain filling stage. The bigger grain size in + GS likely resulted from the longer endosperm cells, which is related to the higher IAA content and expansin activity accompanied by the up-regulation of some expansin-related genes. For the higher grain weight of + GS, starch accumulation was higher in + GS than in -GS, which was consistent with relatively higher glucose (Glu), fructose (Fru), and sucrose (Suc) contents. Elevated sugar level may be correlated with sucrose synthase (SuSy) activity and up-regulation of GBSS I, SSS III, and SBE I. The amount of soluble protein in + GS grains also exceeded that in -GS grains, possibly because of increased NR, NiR, and GS activities and up-regulation of nitrogen assimilation and nitrate transporter genes in + GS grains. Furthermore, the photosynthetic rate was higher in + GS and -GS at the early filling stage before 21 DAA. The same trends were observed in sugar content (Suc, Fru, and Glu) and SPS activity. However, the increase in the rate of grain length and width in + GS plants at the late filling stage was significantly higher than that at the early filling periods. These suggest that high accumulation of dry matter (such as starch and protein) at early filling stage was the important factor in achieving the final increased size of wheat grains, besides cell expansion.

JACoW : SPS slow extraction losses and activation: update on recent improvements

JACoW : SPS slow extraction losses and activation: update on recent improvements

Sugar accumulation and growth of lettuce exposed to different lighting modes of red and blue LED light

The present study evaluated the growth response and sugar accumulation of lettuce exposed to different lighting modes of red and blue LED light based on the same daily light integral (7.49 μmol·m−2). Six lighting treatments were performed, that were monochromatic red light (R), monochromatic blue light (B), simultaneous red and blue light as the control (RB, R:B = 1:1), mixed modes of R, B and RB (R/RB/B, 4 h R to 4 h RB and then 4 h B), and alternating red and blue light with alternating intervals of 4 h and 1 h respectively recorded as R/B(4 h) and R/B(1 h). The Results showed that different irradiation modes led to obvious morphological changes in lettuce. Among all the treatments, the highest fresh and dry weight of lettuce shoot were both detected with R/B(1 h), significantly higher than the other treatments. Compared with plants treated with RB, the contents of fructose, glucose, crude fiber as well as the total sweetness index (TSI) of lettuce were significantly enhanced by R treatment; meanwhile, monochromatic R significantly promoted the activities of sucrose degrading enzymes such as acid invertase (AI) and neutral invertase (NI), while obviously reduced the activity of sucrose synthesizing enzyme (SPS). Additionally. The highest contents of sucrose and starch accompanied with the strongest activity of SPS were detected in plants treated with R/B(1 h). The alternating treatments R/B(4 h) and R/B(1 h) inhibited the activity of SS, while enhanced that of SPS compared with the other treatments, indicating that different light environment might influence sugar compositions via regulating the activities of sucrose metabolism enzymes. On the whole, R/B(1 h) was the optimal lighting strategy in terms of lettuce yield, taste and energy use efficiency in the present study.

Improvement of Sulfamethazine photodegradation by Fe(III) assisted MIL-53(Fe)/percarbonate system

Metal-organic frameworks (MOFs) have attracted tremendous interest as photocatalysis for the destruction of organic contaminants. Herein, we synthesize a Fe-based MOF namely MIL-53(Fe), combined with Fe(III) and percarbonate, exhibits photocatalytic activity for the destruction of Sulfamethazine (SMT) under visible LED light irradiation. The morphology and physicochemical properties of the MIL-53(Fe) were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectra (EDS), Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy (PL). The results indicated that the photocatalytic performance of MIL-53(Fe) with unsatisfactory efficiency resulted from the rapid recombination of photogenerated electrons and holes. This may be suppressed through the introduction of an external electron acceptor (e.g., Fe(III) and percarbonate) to the catalytic process. It could be seen that the SMT degradation efficiency in the system of Vis/MIL-53(Fe)/Fe(III)/SPC attained nearly 90% within 60 min, while only 12% achieved in the system of Vis/MIL-53(Fe). The quenching experiments and EPR analysis were employed to illuminate the predominant reactive species in the system of Vis/MIL-53(Fe)/Fe(III)/SPC. It must be mentioned that the higher separation efficiency of photoinduced electron- hole pairs was achieved via the addition of Fe(III). The accelerated photocatalytic degradation of SMT could be attributed to the subsequent formation of reactive species, which were generated from the activation of SPS by Fe(II) reduced from Fe(III) in the Vis/MIL-53(Fe)/Fe(III)/SPC system. Furthermore, the mineralization of SMT was systematically investigated, as well as the effects of operating parameters (e.g., the dose of catalyst, the concentration of Fe(III), and pH). The work has expanded the possibility of MOFs as visible light responsive photocatalysts together with percarbonate for the remediation of contaminated water.