Invertase Levels Research Articles

Shortage of storage carbohydrates mainly determines seed abscission in Torreya grandis ‘Merrillii’

Torreya grandis cv. Merrillii is a well-known nut in South China with high nutritional value. Severe premature seed abscission limits the industrial development of T. grandis by causing serious economic losses. However, the physiological mechanisms of seed abscission in T. grandis remain poorly understood. To gain insight into the relationships between carbohydrate status and seed abscission, three-year-old seed-bearing branches were taken as representative materials for the entire tree. Furthermore, the time course of changes in the photosynthetic rate and the non-structural carbohydrate (NSC) dynamics were monitored in the main sources (the one-year-old and two-year-old shoots), and the dry weight and NSC levels of sinks (the seeds, current female cone cluster, and current vegetative cluster) across all seed development stages were recorded. The cumulative seed abscission rate significantly increased, reaching 91.5% from 0 to 72 days after seed protrusion time (SPT). NSC levels in the main sources significantly decreased by 56%–79%, accompanied by a significantly increased photosynthesis rate of 17.1%–49.1% during that period and increased NSC levels in the three sinks. The gene expression level of cell wall invertase (TgCWIN) was significantly correlated with sucrose, fructose, and glucose levels. The carbon storage capacity of the main sources significantly decreased from 6.03 to 3.14 mmol C · d−1, with a stable photosynthetic capacity, from 0 to 72 days after SPT, whereas the carbon demand of the three sinks showed a continuously increasing trend from 3.14 to 7.71 mmol C · d−1. In addition, sucrose supplementation significantly decreased the cumulative seed abscission rate. These results suggest that storage carbohydrates play a major role in the regulatory mechanism of seed abscission in T. grandis. Our study provides a theoretical basis for improving T. grandis yield through establishing a better carbon balance between sources and sinks using timely fertilization or proper pruning procedures.

FOLIAR APPLICATION OF SILICON NANOPARTICLES (SiNPs) EFFECTS ON TUBER YIELDS AND CARBOHYDRATE METABOLISM IN FOUR SWEET POTATOE (Ipomoea batatas L) VARIETIES

Silicon nanoparticles (SiNPs) have been widely utilised in agriculture, however, there are limited reports on sweet potatoes (Ipomoea batatas L). In this study, SiNPs were applied as a foliar spray at a concentration of 0.01% (w/v) three times at five-week intervals after planting. Four sweet potato varieties namely ‘Karak Bakar’, ‘Tanjung Sepat’, ‘V6D215’, and ‘Pejabat’ were tested. Results showed that the foliar application of SiNPs induced changes in the tuber biomass, number, epidermal layer thickness, starch, reducing sugar and invertase levels in four sweet potato varieties. The highest tuber biomass was seen in the ‘Pejabat’ (392.9 ± 88.1 g/plant) and ‘Karak Bakar’ (456.6 ± 102.8 g/plant) varieties. SiNPs treatment also reduced the tuber numbers in all varieties except ‘Karak Bakar’ and did not significantly affect (p > 0.05) the starch and reduced sugar content in the tubers of the ‘V6D215’ variety. For all tested varieties, SiNPs treatment did not significantly alter (p > 0.05) the amylase levels and invertase in the tubers of ‘Tanjung Sepat’ and ‘Karak Bakar’. The findings of the study suggested that the effect of foliar application on sweet potatoes is variety-dependent and further study should be carried out to determine the most suitable SiNPs concentration for each variety.

Characterization of physical and chemical properties of honey from Northeastern Anatolia of Türkiye

The aim of this study was to investigate the physical and chemical properties of natural highland honey produced in the northeastern Anatolia region of Turkey. In 2020, 24 honey samples collected and sold during the honey harvest season were purchased from local vendors. Moisture, color, acidity, pH, conductivity, diastase and invertase activity, C13, C13 protein-honey, C4 analysis and sugar components were analyzed in honey samples. The honey samples were found to contain 17.4% moisture. The mean invertase level were found to be 156.216 U/kg. The freshness and enzymatic activity of the honey were shown by the average diastase number of 12.8 DS. The mineral content and overall purity of the honey was indicated by an electrical conductivity value of 0.17 mS/cm. The average acidity value 15.9 meq/kg, fructose/glucose ratio 1.26% and the average color value 33 mm Pfund determined. The average sugar contents in the honey samples were as follows: fructose 37.4%, glucose 29.5%, sucrose 1.4%, turanose 1.8%, maltose 0.6%, isomaltose 0.2%, erlose 0.3%, trehalose 0% hybriditose 0% maltotriose 0% fructose+glucose. 66.9%, fructose/glucose 1.26, glucose/water 2.0. The mean difference between honey protein and honey delta C13 data is -0.58 and C4 sugar ratio is 0. In conclusion, valuable findings were obtained on the physical and chemical properties of honey from the northeastern Anatolia region of Turkey. Further research can build on these findings to explore the unique properties and potential benefits of honey from this region and contribute to its value and utilization in various industries.

Insecticidal Activity of Tannins from Selected Brown Macroalgae against the Cotton Leafhopper Amrasca devastans.

Seaweeds, also known as marine macroalgae, are renewable biological resources that are found worldwide and possess a wide variety of secondary metabolites, including tannins. Drifted brown seaweed (DBSW) is particularly rich in tannins and is regarded as biological trash. The cotton leaf hopper Amrasca devastans (Distant) has caused both quantitative and qualitative losses in cotton production. Drifted brown seaweeds (DBSWs) were used in this study to extract, qualitatively profile, and quantify the levels of total tannins, condensed tannins, hydrolyzable tannins, and phlorotannins in the seaweeds; test their insecticidal activity; and determine the mechanism of action. The largest amount of tannin extract was found in Sargassum wightii Greville (20.62%) using the Soxhlet method (SM). Significantly higher amounts of hydrolyzable tannins (p = 0.005), soluble phlorotannins (p = 0.005), total tannins in the SM (p = 0.003), and total tannins in the cold percolation method (p = 0.005) were recorded in S. wightii. However, high levels of condensed tannins (CTAs) were observed in Turbinaria ornata (Turner) J. Agardh (p = 0.004). A. devastans nymphs and adults were examined for oral toxicity (OT) and contact toxicity (CT) against DBSW tannin crude extract and column chromatographic fractions 1 (Rf = 0.86) and 2 (Rf = 0.88). Stoechospermum polypodioides (J.V. Lamouroux) J. Agardh crude tannin was highly effective against A. devastans using the OT method (LC50, 0.044%) when compared with the standard gallic acid (LC50, 0.044%) and tannic acid (LC50, 0.122%). Similarly, S. wightii fraction 2 (LC50, 0.007%) showed a greater insecticidal effect against A. devastans adults in OT than gallic acid (LC50, 0.034%) and tannic acid (LC50, 0.022%). The mechanism of action results show that A. devastans adults treated with crude tannin of T. ornata had significantly decreased amylase, protease (p = 0.005), and invertase (p = 0.003) levels when compared with the detoxification enzymes. The levels of glycosidase, lactate dehydrogenase, esterase, lipase, invertase, and acid phosphate activities (p = 0.005) of S. wightii were reduced when compared with those of the Vijayneem and chemical pesticide Monocrotophos. In adult insects treated with LC50 concentrations of S. wightii tannin fraction 1, the total body protein (9.00 µg/µL) was significantly reduced (OT, LC50-0.019%). The SDS-PAGE analysis results also show that S. wightii tannin fraction 1 (OT and CT), fraction 2 (OT), and S. polypodioides fraction 2 (CT) had a significant effect on the total body portion level, appearance, and disappearance of some proteins and polypeptides. This study shows that the selected brown macroalgae can be utilized for the safer management of cotton leaf hoppers.

Differences in the Production of Extracellular Polymeric Substances (EPS) and Other Metabolites of Plenodomus (Leptosphaeria) Infecting Winter Oilseed Rape (Brassica napus L.).

Species of the genus Plenodomus (Leptosphaeria) are phytopathogens of the Brassicaceae family, which includes oilseed rape. The spores of these fungi spread by airborne transmission, infect plants, and cause crop losses. The secondary metabolism of P. lingam and P. biglobosus was studied and compared, with the main focus being on the ability to produce Extracellular Polymeric Substances (EPS). In spite of the 1.5-2-fold faster growth rate of P. biglobosus on Czapek-Dox and other screening media, the average yield of EPS in this fungus was only 0.29 g/L, compared to that of P. lingam (0.43 g/L). In turn, P. biglobosus showed a higher capacity to synthesise IAA, i.e., 14 µg/mL, in contrast to <1.5 µg/mL produced by P. lingam. On the other hand, the P. lingam strains showed higher β-glucanase activity (350-400 mU/mL), compared to 50-100 mU/mL in P. biglobosus. Invertase levels were similar in both species (250 mU/mL). The positive correlation between invertase activity and EPS yield contrasted with the absence of a correlation of EPS with β-glucanase. Plenodomus neither solubilised phosphate nor used proteins from milk. All strains showed the ability to synthesise siderophores on CAS agar. P. biglobosus exhibited the highest efficiency of amylolytic and cellulolytic activity.

Accumulation of complex oligosaccharides and CAZymes activity under acid conditions constitute the Thatcher+Lr9 defence responses to Puccinia triticina

Puccinia triticina (Pt) is an important pathogen of wheat. While breeding programmes develop resistant wheat cultivars to mitigate the effects of such rust-causing pathogens, the emergence of new rust races with wider virulence mandates the implementation of other control strategies. Our study investigated whether acidic pH conditions affected selected Carbohydrate-Active Enzymes (CAZymes) in Pt-inoculated Thatcher + Lr9 (IR) wheat compared to those found in the Thatcher (IS) wheat. The β-glucosidase and amyloglucosidase activity levels significantly increased in IR compared to the control from 1 to 14 days post-inoculation (dpi). In contrast, activity levels of invertase did not change in the IR wheat relative to the control at 1 and 7 dpi, but were significantly reduced in the IR plants at 14 dpi. The IS had higher activity of all three hexose-producing enzymes under acidic conditions. These enzyme activities could be increased in the IS to produce hexose sugars required by Pt to develop and advance infection. The phenotypic analysis supported this view because leaf rust disease symptoms were only visible in the IS plants. For cell wall loosening-related enzymes, the IR displayed higher activity of exoglucanase, xylanase and peroxidase enzymes compared to IS. The liquid chromatography–mass spectrometry analysis showed IR had higher concentrations of complex oligosaccharides compared to the IS. Thus, we concluded that the higher exoglucanase, xylanase and peroxidase activity could be involved in cell wall loosening under acidic conditions, while oligosaccharides could be building-blocks for synthesizing cell wall barriers that apprehend Pt growth in inoculated Thatcher + Lr9.

Links between chemical composition of soil organic matter and soil enzyme activity in alpine grassland ecosystems of the Tibetan Plateau

Soil enzymes play a key role in soil organic matter dynamics in terrestrial ecosystems; however, the relationship between soil enzyme activity and the chemical composition of soil organic matter remains unclear. We analysed the soil organic matter (SOM) of five types of alpine grassland ecosystems in the Tibetan Plateau at the molecular level using pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), which allowed us to examine the relationship between the patterns of enzyme activities and SOM composition. We found that the level of activity of carbon (C)-cycling enzymes (invertase, β-1,4-glucosidase, polyphenol oxidase, and peroxidase), nitrogen (N)-cycling enzymes (arylamidase), and phosphorus (P)-cycling enzyme (alkaline phosphatase) was significantly different among the five grassland ecosystems. In addition, we found significant variation among the different grassland ecosystems in terms of the activity of enzymes involved in C-cycling less so with those enzymes involved in N-cycling. In general, SOM was dominated by N-compounds (∼32.47–51.76%), polysaccharides (∼10.67–20.42%), and fatty acids (∼7.03–20.33%) in the different alpine grasslands. The most abundant compounds in SOM were D-alanine (10.06–20.77%), 9-octadecenamide, (Z) (4.43–9.68%), and 13-docosenamide (1.52–14.76%). Correlation analysis showed that the N-compound abundance was negatively correlated with nitrate reductase. Polysaccharides were positively correlated with activity levels of invertase and cellulase. Fatty acids were positively correlated with polyphenol oxidase activity and negatively correlated with alkaline phosphatase activity. Some abundant compounds consistently showed strong correlations with activity levels of invertase and cellulase, including toluene, styrene, benzene, phenol, furfural, pyrrole, p-cresol, 2-methylphenylacetylene and indole (positive correlation), 13-docosenamide, dodecanamide and o-hydroxybiphenyl (negative correlation). Furthermore, Gram-positive and Gram-negative bacteria also play a significant role in regulating SOM-enzyme interactions. These findings confirmed the strong effects of SOM composition on the activity of invertase and cellulase, indicating that invertase and cellulase play an important role in regulating SOM to some extent, resulting in complex interactions among organic-enzyme-microbes.

Alternating red and blue irradiation affects carbohydrate accumulation and sucrose metabolism in butterhead lettuce

• Different irradiation patterns of red (R) and blue LED light (B) including alternating, concurrent, and monochromatic modes have been conducted on lettuce and compared from the angel of growth, energetic efficiency and sugar metabolism of lettuce. • The alternating R/B modes have been proved to increase the biomass and soluble sugar accumulation in lettuce on the basis of the same daily amount of photons and electric energy consumption as the concurrent RB. • The promotion effects of alternating R/B was relevant to the alternating interval of r and B, and the alternating R/B with appropriate interval could be considered as energy efficient irradiation mode for lettuce in a plant factory with artificial light (PFAL). • The alternating R/B modes have been proved to influence the activities and gene expression of the sucrose-metabolism related enzymes in lettuce, thus affected the carbohydrate accumulation and the development of lettuce. Sucrose metabolism and carbohydrate accumulation were evaluated in butterhead lettuce cultured under alternating red light (R) and blue light (B) irradiance. The R/B treatments were respectively R/B(5 m) (i.e. R 5 min/B 5 min), R/B(10 m), R/B(15 m), R/B(30 m) and R/B(60 m). Meanwhile, concurrent R and B (RB) as well as monochromatic R (R) and monochromatic B (B) were conducted. Compared with concurrent RB, all the alternating R/B treatments increased the fresh weight (FW), dry weight (DW) and the content of pigment and soluble sugar in lettuce on the basis of the same daily photon amount and electric energy consumption. Lettuce exposed to R/B(30 m) required the least number of photons (1.82 μmol) and electricity (1.04 MJ) per gram DW produced among all the treatments, thus R/B(30 m) was the recommended lighting mode in terms of the use efficiency of photons and electricity. Relatively higher soluble sugar content and the total sweetness index (TSI), as well as lower crude fiber content were detected in lettuce subjected to R/B(60 m), which was regarded as optimal irradiation mode in terms of lettuce taste. The content of sucrose, glucose and fructose, and the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SS) in the synthesis direction, as well as the gene expression level of SPS in lettuce were all enhanced by the alternating irradiation of R/B (15 m), R/B (30 m) and R/B (60 m) in comparison to the concurrent RB treatment. Moreover, higher enzyme activities in the synthetic direction of sucrose were found to be accompanied with higher soluble sugar content in lettuce subjected to R/B (30 m), R/B (60 m) and the solely R, indicating that the enzyme activities in sucrose synthetic direction seemed more related to the soluble sugar accumulation in lettuce. The results also showed that SS in lettuce leaves mainly acted on sucrose decomposition rather than synthesis. The hexose (glucose and fructose) content of lettuce subjected to R/B(60 m) basically kept the highest level among all the treatments through the whole processing period, which might be due to that lettuce exposed to R/B (60 m) owned the highest gene expression level of SS and invertase, as well as the highest enzyme activities of SS (cleavage) and invertase among all the treatments. Solely B inhibited the gene expression of sucrose metabolism-related enzymes in lettuce, and the photon use efficiency to R by lettuce was higher than to B from the angle of biomass and soluble sugar accumulation. A low intensity of B (1/9 of the R level) alternating with R improved the photon and electric use efficiency of lettuce in this study.

Difference and molecular mechanism of soluble sugar metabolism and quality of different rice panicle in &amp;lt;italic&amp;gt;japonica&amp;lt;/italic&amp;gt; rice

<p id="C3">This study investigated the mechanism of starch and rice quality differences on different parts of spikelet in <italic>japonica</italic> rice. According to the internodes of the primary stem on main panicle, rice grains on the panicles were divided into top, middle, and the bottom spikelets. The dynamic changes of soluble carbohydrate and starch, starch biosynthesis related enzyme activity, gene expression on different parts of panicles at different filling stage and the starch content, chalkiness degree after harvest of six varieties were measured. The results showed that the amylose content of the five varieties was in an order as top &gt; middle &gt; bottom except Xiushui 134. The chalkiness degree of Jia 58 and Zhongjia 8 was higher than the other varieties, and the chalkiness degree of rice grains on the middle part of panicles was lower than that on the bottom part, and the rice grains on the top part had the highest chalkiness degree. Rice grains of high chalkiness degree had significant difference in starch granules size and shape. We found that the shape of starch granules was semi-ellipsoid or other spherical curved in rice grains with high chalkiness degree and mostly regular polyhedra in rice grains with low chalkiness degree. The contents of sucrose, glucose, and fructose in grains of different varieties and parts were different during grain filling period, but the dynamic changes of sucrose content were first decreased and then slightly increased, while glucose and fructose were basically increased first and then decreased. The contents of invertase and AGPase were significantly different among rice grains on top, middle, and bottom parts of panicles. However, the relative expression levels of AGPase were in an order as top &gt; middle &gt; bottom during the whole filling stage. The relative expression levels of invertase were in an order as top &lt; middle &lt; bottom during the early filling stage, and the rule was completely the opposite at late filling stage. The expression levels of <italic>OsCIN2 </italic>and<italic> OsCIN5</italic> encoding sucrose invertase genes were in an order as middle &gt; bottom &gt; top, and the expression levels of <italic>OsAGPL1</italic>,<italic> OsAGPL2</italic>, and <italic>OsAGPS1a</italic> encoding AGPase genes were in an order as top &gt; middle ≈ bottom. It concluded that the amylose content and chalkiness degree of grains in different panicles had significant difference and also affected by varieties. The content of soluble carbohydrate, starch biosynthesis related enzyme activity, and the gene expression of encoding related enzymes had an effect on starch biosynthesis. The genes of <italic>OsCIN2, OsCIN5, OsAGPL1</italic>,<italic> OsAGPL2</italic>, and<italic> OsAGPS1a</italic> played an important role in the difference of starch content and chalkiness degree in different panicles.

Comparative analysis of carbon and nitrogen metabolism, antioxidant indexes, polysaccharides and lobetyolin changes of different tissues from Codonopsis pilosula co-inoculated with Trichoderma

Codonopsis pilosula is a traditional Chinese herbal medicinal plant and contains various bioactive components, such as C. pilosula polysaccharides (CPPs) and lobetyolin (Lob). Hydrogen peroxide (H2O2) and nitric oxide (NO) are gaseous molecule and have been well known for their ability to relieve some adverse influences on plant from abiotic stress. Endophytic fungus is non-pathogenic plant-associated fungus that could play a significant role in improving plant tolerance by signal molecule. In this work, we determined how inoculation of Trichoderma strain RHTA01 with C. pilosula changed the plant's growth, metabolite accumulation, and related enzyme activity. Results demonstrated that application of Trichoderma strain RHTA01 significantly improved the growth of C. pilosula. Moreover, it noticeably decreased antioxidant enzyme superoxide dismutase (SOD) and catalase (CAT) activity in C. pilosula leaves, reduced the content of H2O2 and malondialdehyde (MDA), and weakened the peroxidation of cell membrane lipids, which reduced the damage of abiotic stress to C. pilosula. Research has shown that it had obvious effects on levels of nitrogen and carbon metabolic enzymes. For example, sucrose synthase (SS) and acid invertase (AI) levels in C. pilosula roots were nearly 1.43 and 1.7 times higher, respectively, than those in the control (CK) group. In addition, it was notable that the production of CPPs and Lob, the most significant secondary metabolites in C. pilosula, were influenced by Trichoderma strain RHTA01. The obtained results indicate that inoculating C. pilosula with Trichoderma stimulates the carbon and nitrogen metabolism of the plant, and helps to increase the content of CPPs and Lob in the root of the plant.

Morphological and physiological characteristics of abnormal berry development in Vitis amurensis

Heterogeneity among grape berries directly affects wine quality and restricts the wine grape industry’s development. To study the heterogeneous development of Vitis amurensis berries, the morphology and physiology of three different types—large berry, medium berry, and live green ovary (LGO)—in the same clusters of wine-making cultivar ‘Shuangfeng’ were monitored at different growth stages from June to September. External differences in berry development were distinguishable at 12 days after full bloom (DAF). The pedicel, berry size, fresh weight, and seed length of the medium berries were intermediate between those of large berries and LGOs. Seeds are crucial for fruit set and normal berry development. The activity levels of soluble acid invertase and cell-wall-bound acid invertase in large berries increased earlier, at 18 DAF, than the accumulation of sugar. Abscisic acid concentrations in medium berries and LGOs were greater than that in large berries at 18 DAF. The greater endogenous indole-3-acetic acid concentration in the medium berries compared with LGOs might protect the former from abscission.

Suppression of sugar accumulation in coleoptile and mesocotyl cells by light irradiation to etiolated maize seedlings

Sugar accumulation in maize (Zea mays) coleoptile and mesocotyl cells was suppressed when etiolated seedlings were subjected to white light irradiation. Regulation mechanisms of sugar accumulation by light in cells of both organs were studied. Sucrose exudation from the endosperm was suppressed in light-treated seedlings. In addition, the activities and transcript levels of sucrose-phosphate synthase (SPS) in scutella were decreased following light irradiation. These results suggest that sucrose exudation from the endosperm is decreased by the suppression of SPS activities via downregulation of its gene expression. In coleoptiles and mesocotyls, light irradiation also decreased the activities and transcript levels of cell wall-bound invertase, suggesting that phloem unloading processes were suppressed. Thus, inhibition of both sucrose loading from the endosperm and sucrose unloading in coleoptiles and mesocotyls may be involved in the suppression of sugar accumulation in coleoptiles and mesocotyls irradiated with white light.

Investigation of Variations of Invertase and Glucose Oxidase Degrees against Heating and Timing Options in Raw Honeys

Invertase and glucose oxidase are secreted by the hypopharyngeal glands of honeybees for the hydrolysis of sucrose and the preservation from microbial effects, respectively. It is also prominent to understand how the levels of invertase and glucose oxidase of raw honey samples are being influenced by different conditions because the behavior of these specific enzymes in raw honeys could be a marker for the quality parameters. On the basis of this expectation, three raw honey samples tagged as blossom, pine, and oak were investigated. To reach the desired aim, extraction conditions were diversified by the range of different periods as 0, 1, 3, and 6 h and of different temperatures as 24, 45, and 65°C. The optimal heating condition and the period of extraction for invertase activity of all honey types were 24°C and 1 h because data of this condition were 147.960–178.266 enzyme unit per kilogram (U/kg) and 20.179–24.313 invertase number (IN). Although the variety of glucose oxidase activity was not evaluated as a worthwhile indicator of quality for raw honey due to its abnormal activity behavior, the change of invertase activity should be considered as a quality parameter due to showing the gradual decreasing level from initially a quite high one.

The Tolerance of Salinity in Rice Requires the Presence of a Functional Copy of FLN2.

A panel of ethane-methyl-sulfonate-mutagenized japonica rice lines was grown in the presence of salinity in order to identify genes required for the expression of salinity tolerance. A highly nontolerant selection proved to harbor a mutation in FLN2, a gene which encodes fructokinase-like protein2. Exposure of wild-type rice to salinity up-regulated FLN2, while a CRISPR/Cas9-generated FLN2 knockout line was hypersensitive to the stress. Both ribulose 1,5-bisphosphate carboxylase/oxygenase activity and the abundance of the transcript generated by a number of genes encoding components of sucrose synthesis were lower in the knockout line than in wild-type plants’ leaves, while the sucrose contents of the leaf and root were, respectively, markedly increased and decreased. That sugar partitioning to the roots was impaired in FLN2 knockout plants was confirmed by the observation that several genes involved in carbon transport were down-regulated in both the leaf and in the leaf sheath. The levels of sucrose synthase, acid invertase, and neutral invertase activity were distinctly lower in the knockout plants’ roots than in those of wild-type plants, particularly when the plants were exposed to salinity stress. The compromised salinity tolerance exhibited by the FLN2 knockout plants was likely a consequence of an inadequate supply of the assimilate required to support growth, a problem which was rectifiable by providing an exogenous supply of sucrose. The conclusion was that FLN2, on account of its influence over sugar metabolism, is important in the context of seedling growth and the rice plant’s response to salinity stress.

Decrement of Sugar Consumption in Rice Young Panicle Under High Temperature Aggravates Spikelet Number Reduction

Two rice genotypes Huanghuazhan (HHZ, heat-resistant) and IR36 (heat-susceptible) were subjected to high-temperature (HT, 40°C) and normal-temperature (NT, 32°C) treatments at the spikelet differentiation stage. HT treatment inhibited spikelet differentiation, aggravated spikelet degeneration, reduced spikelet size, and disordered carbohydrate allocation. Meanwhile, HT treatment increased nonstructural carbohydrate content in leaves, but decreased that in stems and young panicles, and the same tendencies of sucrose and starch contents were observed in leaves and stem. However, HT treatment significantly increased the sucrose content and sharply decreased the glucose and fructose contents in young panicles. Lower activity levels of soluble acid invertase (EC3.2.1.26) and sucrose synthase (EC2.4.1.13) were observed under HT treatment. Moreover, HT treatment reduced the activities of key enzymes associated with glycolysis and the tricarboxylic acid cycle, which indicated sucrose consumption was inhibited in young panicles under HT treatment. Exogenous glucose and fructose applied under HT treatment increased the spikelet number more than exogenous sucrose. In conclusion, the results demonstrated that the reduction of spikelet number under high temperature was more affected by the decrease in sugar consumption than the blocking of sucrose transport. The impairment of sucrose hydrolysis was the main reason for the inhibition of sugar utilization.

Glycine betaine alleviated peel browning in cold-stored ‘Nanguo’ pears during shelf life by regulating phenylpropanoid and soluble sugar metabolisms

Long-term cold storage can postpone the senescence and preserve the quality of postharvest ‘Nanguo’ pear fruit. However, peel browning (PB), which is deemed to be a symptom of chilling injury (CI), usually develops after the fruit are transferred to shelf life at room temperature. In this study, the effect of glycine betaine (GB) treatment (10 mmol L−1 for 10 min) on PB, as well as on phenylpropanoid and soluble sugar metabolisms of pear fruit was investigated. The results showed that GB treatment effectively delayed the occurrence of PB by 6 d after cold storage for 120 d, and significantly inhibited the browning index in fruit by more than 35% during the 15 d of shelf life. Enzymes activities and genes expression levels related to phenylpropanoid metabolism were increased after GB treatment, which resulted in the increase of total phenols and flavonoids content. Moreover, higher sucrose content, and lower fructose and glucose content were observed in GB-treated fruit, which was concomitant with increased activities and genes expression levels of sucrose synthase (SS) and sucrose phosphate synthase (SPS), as well as decreased activities and genes expression levels of invertase. The results showed that the development of PB in cold-stored ‘Nanguo’ pears was closely related to phenylpropanoid and soluble sugar metabolisms. GB treatment could alleviate PB by ways of regulating phenylpropanoid and soluble sugar metabolisms, as well as by sustaining higher levels of phenolic and sucrose content. Therefore, exogenous GB treatment could be an effective method to alleviate PB of ‘Nanguo’ pear fruit during cold storage.

Influence of long-term cold storage on phenylpropanoid and soluble sugar metabolisms accompanied with peel browning of ‘Nanguo’ pears during subsequent shelf life

Cold storage can effectively postpone the senescence of postharvest ‘Nanguo’ pear fruit. However, peel browning (PB) usually develops after the fruit are transferred to shelf life at room temperature. In this study, influence of cold storage on phenylpropanoid and soluble sugar metabolisms accompanied PB in pears was investigated. Increased PB and decreased phenolics compounds were observed with the extension of cold storage. The activities and genes expression levels of enzymes involved in phenylpropanoid metabolism were restrained by long-term cold storage. Meanwhile, lower content of sucrose and sorbitol, and higher content of fructose and glucose were detected as the prolonging of storage time, accompanied by decreased activities and genes expression levels of sucrose synthase (SS) and sucrose phosphate synthase (SPS), and increased activities and genes expression levels of invertase. The results showed that the occurrence of PB in pears after long-term cold storage was closely related to phenylpropanoid and soluble sugar metabolisms, and the possible mechanisms are discussed.

Genome-wide characterization of the NUCLEAR FACTOR-Y (NF-Y) family in Citrus grandis identified CgNF-YB9 involved in the fructose and glucose accumulation

Nuclear factor Y (NF-Y) is increasingly known to be involved in many aspects of plant growth and development. To date, the systematic characterization of NF-Y family has never been reported in Citrus grandis. Genome-wide characterization of C. grandis NF-Y (CgNF-Y) family and analysis of their role in sucrose metabolism. NF-Y conserved models were employed to identify CgNF-Y genes from genomic data. Phylogenetic tree was generated by the neighbor-joining method using program MEGA 7.0. Based on our previous transcriptomic data, the transcription levels were calculated by RSEM software and were clustered by ShortTime-series Expression Miner. The plant expression vector of CgNF-YB9 was constructed using In-Fusion Cloning and transferred into tobacco by leaf disc transformation method. Soluble sugars and gene expressions were analysis by HPLC and qRT-PCR, respectively. A total of 24 CgNF-Y genes (6 CgNF-YAs, 13 CgNF-YBs and 5 CgNF-YCs) were identified with conserved domains. Phylogenetic analysis of the NF-Y proteins indicated that NF-YA, NF-YB and NF-YC could be categorized into four, five and three clades, respectively. Expression profiling analysis reflected spatio-temporally distinct expression patterns for CgNF-Y genes. Importantly, we observed a positive correlation between the expression level of CgNF-YB9 and the content of soluble sugar. Moreover, CgNF-YB9-corelated genes were enriched in carbohydrate metabolism. In CgNF-YB9 overexpression lines, sucrose content showed a decrease, whereas glucose and fructose contents displayed an increase. As expected, the transcription levels of sucrose-phosphate synthase and vacuolar invertase in transgenic Line 3 were observed with significantly down- and up-regulated, respectively. The structure, phylogenetic relationship and expression pattern of 24 CgNF-Y genes were identified, and CgNF-YB9 was involved in sucrose metabolism.

Effects of exogenous plant hormones on sugar accumulation and related enzyme activities during the development of longan (Dimocarpus Longan Lour.) fruits

ABSTRACTExogenous hormone treatment is a widely used and effective method to promote fruit ripening. To our knowledge, the effects of exogenous hormones on the sugar accumulation and related enzyme activities during the development of longan fruits have not yet been elucidated. In this study, the contents of sucrose, glucose and fructose, activities and transcriptional levels of sucrose phosphate synthase (SPS), sucrose synthase (SS), acid invertase (AI) and neutral invertase (NI) were detected during fruit development of exogenous hormone-treated and non-treated longan. The results indicated that exogenous hormones (IAA, ABA, GA3) could not alter the sugar contents when fruits were ripe but accelerate the sugar accumulation. IAA and ABA increased the gene transcriptional levels and enzyme activities of SS and SPS, and also showed the tendency of increasing the transcriptional levels and enzyme activity of AI. However, GA3 decreased the gene transcriptional levels of SS and SPS, and increased the gene transcriptional level of AI. Interestingly, GA3 also increased the enzyme activity of SPS which indicated GA3 may regulate the SPS activity at post-translational levels. Our results suggested that IAA, ABA and GA3 may regulate sugar accumulation during fruit development of longan.

Macroalgae bloom decay decreases the sediment organic carbon sequestration potential in tropical seagrass meadows of the South China Sea

Seagrass meadows are experiencing worldwide declines mainly because of nutrient enrichment, which always result in macroalgae bloom and consequently periodic collapse and decomposition. However, effects of macroalgae decay on the sediment organic carbon (SOC) sequestration capacity remain unknown. Depending on the macroalgae biomass in eutrophic seagrass meadows of South China Sea, we carried out a laboratory chamber experiment to investigate the sediment labile organic carbon (OC) compositions and the influencing SOC transformation enzyme activity variations of seagrass meadows in response to common macroalgae bloom species (Cladophora spp.) decomposition. Although the dehydrogenase and β-glucosidase activities were not affected by macroalgae decomposition, the macroalgae decomposition significantly elevated the salt-extractable carbon (SEC) content, SEC/SOC, levels of invertase and polyphenol oxidase activities, and the CO2 release. Overall, this study indicates that macroalgae decomposition stimulates the SOC transformation, and therefore, it is not benefit for SOC sequestration within seagrass meadows of the South China Sea.