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Abstract Drought stress can negatively impact crop yield and quality. Improving wheat yields under drought stress is a major objective of agronomic research. Glutamine synthetase (GS) is a key enzyme of nitrogen metabolism that is critical to plant growth and development in abiotic stress response. However, to date, no systemic characterization of the GS genes has yet been conducted in wheat and its close relatives. We identified a total of 15 GS genes in Triticum aestivum (2n = 6x = 42; AABBDD), as well as 9 GS genes in Triticum dicoccoides (2n = 4x = 28; AABB), 6 in Aegilops tauschii (2n = 2x = 14; DD), and 5 in Triticum urartu (2n = 2x = 14; AA). The 35 GSs were further clustered into five lineages according to the phylogenetic tree. Synteny analysis revealed that the three subgenomes in bread wheat retained extensive synteny between bread wheat and its three relative species. We identified three up-regulated TaGSs (Ta4A.GSe, Ta4B.GSe, and Ta4D.GSe) from transcriptome data after drought and salt stress. Ta4D.GSe was subsequently used for further functional studies, and its subcellular localization were determined in Arabidopsis protoplasts. Its overexpression in Arabidopsis enhanced drought tolerance by increasing the ability of scavenging of reactive oxygen species (ROS) and osmotic adjustment. We identified GS gene family in four wheat species and performed comparative analyses of their relationships, chromosome locations, conserved motif, gene structure, and synteny. The subcellular localization of Ta4D.GSe was detected and its drought tolerance function was demonstrated. Taken together, these findings provide insight into the potential functional roles of the GS genes in abiotic stress tolerance. Key message This report clearly shows detailed characterization of GS gene family in four wheat species and demonstrates that Ta4D.GSe plays an important role in enhancing drought tolerance by improving the scavenging of ROS and osmotic adjustment ability in Arabidopsis.

Tree peony bud endodormancy is a common survival strategy similar to many perennial woody plants in winter, and the activation of the GA signaling pathway is the key to breaking endodormancy. GA signal transduction is involved in many physiological processes. Although the GA-GID1-DELLA regulatory module is conserved in many plants, it has a set of specific components that add complexity to the GA response mechanism. DELLA proteins are key switches in GA signaling. Therefore, there is an urgent need to identify the key DELLA proteins involved in tree peony bud dormancy release. In this study, the prolonged chilling increased the content of endogenously active gibberellins. PsRGL1 among three DELLA proteins was significantly downregulated during chilling- and exogenous GA3-induced bud dormancy release by cell-free degradation assay, and a high level of polyubiquitination was detected. Silencing PsRGL1 accelerated bud dormancy release by increasing the expression of the genes associated with dormancy release, including PsCYCD, PsEBB1, PsEBB3, PsBG6, and PsBG9. Three F-box protein family members responded to chilling and GA3 treatments, resulting in PsF-box1 induction. Yeast two-hybrid and BiFC assays indicated that only PsF-box1 could bind to PsRGL1, and the binding site was in the C-terminal domain. PsF-box1 overexpression promoted dormancy release and upregulated the expression of the dormancy-related genes. In addition, yeast two-hybrid and pull-down assays showed that PsF-box1 also interacted with PsSKP1 to form an E3 ubiquitin ligase. These findings enriched the molecular mechanism of the GA signaling pathway during dormancy release, and enhanced the understanding of tree peony bud endodormancy.

MicroRNAs (miRNAs) are non-coding RNAs that interact with target genes and are involved in many physiological processes in plants. miR172-AP2 mainly plays a role in the regulation of flowering time and floral organ differentiation. Bud dormancy release is necessary for forcing culture of tree peony in winter, but the mechanism of dormancy regulation is unclear. In this study, we found that a miR172 family member, PsmiR172b, was downregulated during chilling-induced bud dormancy release in tree peony, exhibiting a trend opposite to that of PsTOE3. RNA ligase-mediated (RLM) 5′-RACE (rapid amplification of cDNA ends) confirmed that miR172b targeted PsTOE3, and the cleavage site was between bases 12 (T) and 13 (C) within the complementary site to miR172b. The functions of miR172b and PsTOE3 were detected by virus-induced gene silencing (VIGS) and their overexpression in tree peony buds. PsmiR172b negatively regulated bud dormancy release, but PsTOE3 promoted bud dormancy release, and the genes associated with bud dormancy release, including PsEBB1, PsEBB3, PsCYCD, and PsBG6, were upregulated. Further analysis indicated that PsTOE3 directly regulated PsEBB1 by binding to its promoter, and the specific binding site was a C-repeat (ACCGAC). Ectopic expression in Arabidopsis revealed that the PsmiR172b-PsTOE3 module displayed conservative function in regulating flowering. In conclusion, our results provided a novel insight into the functions of PsmiR172-PsTOE3 and possible molecular mechanism underlying bud dormancy release in tree peony.

Bud endodormancy is accompanied by transport channel apertures blockage through callose deposition, and its resume to growth requires evoking β-1,3-glucanases (BGs) to unchoke the conduit. To understand out its working manner, the statuses of the transport channels were evaluated and candidate BGs were identified during chilling and gibberellin acids (GA) induced dormancy release in tree peony. Calcein reflects plasmodesmata permeability, and no calcein was observed in the bud together with density aniline blue fluorescent around the stem phloem at 0 d chilling. With the increase of chilling accumulation, the contents of glucan declined and the activities of gulcanase increased gradually in buds, and the calcein reached the top of flower primordia at 21 d chilled bud. Both GA3 and GA4 feedings promoted bud sprouting and growth along with rapidly unchoking the transport channels, and GA3 was more effective. Several candidate β-1,3-glucanase genes were detected, combining transcriptional profiling and quantitative PCR analysis. PsBG1, PsBG3, PsBG6, PsBG8 and PsBG9 were inducible by chilling accumulation and presented laminarin hydrolyzing activities after prokaryotically expression, while PsBG1, PsBG3, PsBG8 and PsBG9 responded to GAs application. Subcellular localizations revealed that PsBG6 and PsBG9 were plasmodesmata residents. It was concluded that PsBG6 played a vital role in chilling accumulation response and PsBG9 was central in GAs-induced dormancy release, and they could be used as marker genes for dormancy release in tree peony. These results were of great value to understand the mechanism of dormancy regulation and as an important fundamental for forcing culture technology in tree peony.

As a crop irrigated primarily by rain, the quality and yield of peanuts are significantly limited by drought. To date, many studies have indicated that fatty acid desaturase (

DNA methylation is an important epigenetic regulator of gene expression. Application of 5-azacytidine (a methylation inhibitor) significantly promoted bud sprouting rate and the elongation of branches and leaves in "Luhehong" and "Fengdanbai." In total, 11,166 and 11,443 fragments were obtained by methylation-sensitive amplified polymorphism (MSAP) analysis during chilling-induced dormancy release in the two varieties, respectively. Total methylation levels were high in dormant buds, mainly for hemimethylation, which were slowly increased by short-term chilling (7 days) and decreased by long-term chilling. Compared with 0 day, the ratio of the methylation downregulated group increased during dormancy release, whereas that of the upregulated group declined gradually. These variations were consistent with the dynamic expressions of DNA methyltransferase/demethylase genes and their enzyme activity changes. In total, 13 polymorphic MSAP fragments were similar to known proteins (E-value

To optimize the spatial distribution of cotton bolls and to increase the yield, the relationship between yield components and boll spatial distribution was investigated among different Bt (Bacillus thuringensis) cotton varieties. A five-year field experiment was conducted to reveal the reasons for the differences in lint yield and fiber quality across three Bt cotton varieties with different yield formations from 2013 to 2017. The lint yield of Jiman 169 (the average yield from 2013–2017 was 42.2 g/plant) was the highest, i.e., 16.3 and 36.9% higher than Lumianyan 21 (L21) and Daizimian 99B (99B), respectively. And the differences in boll weight among the three cultivars were similar to the lint yield, while the others yield components were not. So the increase in lint yield was mainly attributed to the enlargement in boll weight. However, the change in fiber quality was inconsistent with the lint yield, and the quality of L21 was significantly better than that of Jimian 169 (J169) and 99B, which was caused by the diversity of boll spatial distribution. Compared with 99B, the loose-type J169 had the highest number of large bolls in inner positions; the tight-type L21 had a few large bolls and the highest number of lower and middle bolls. And approximately 80.72% of the lint yield was concentrated on the inner nodes in Jiman 169, compared with 77.44% of L21 and 66.73% of 99B during the five-year experiment. Although lint yield was significantly affected by the interannual changes, the lint yield of J169 was the highest and the most stable, as well as its yield components. These observations demonstrated the increase in lint yield was due to the increase in boll weight, and the large bolls and high fiber quality were attributed to the optimal distribution of bolls within the canopies.

Upland cotton makes an important contribution to natural fiber production worldwide. Given the necessity to high quality fiber required in the textile industry, the genomic variation of diverse accessions and the loci underpinning fiber quality should be extensively investigated. Here, a panel of 196 upland cottons and 41,815 single-nucleotide polymorphism (SNP) markers were examined for detection of candidate quantitative trait loci (QTL) for five fiber quality traits in six environments using both single- and multi-locus genome-wide association studies (GWAS) models. With discriminant analysis of principal components (DAPC), the accessions were divided into four subpopulations, and among these, 40 SNPs and 38 QTL were significant in at least three environments and at least two models. Reference to the TM-1 genome and related gene expression data, 89 candidate genes preferentially expressed in fiber or ovules were identified. In this study, 23 candidate QTL and 71 candidate genes were also identified in previous studies, and of them, five promising QTL and 13 promising genes may have pleiotropic effects. In addition, nine putative genes were identified with quantitative real-time PCR. Furthermore, 17 common genes between fiber quality traits and cottonseed nutritional traits were identified. All of the SNP markers and promising genes detected in this study could be used in future breeding practices and for putative gene functional studies.

Stubble return is a proposed practice for soil amelioration and yield improvement. However, from the perspective of reducing soil salinity and improving soil nutrient availability, we have little knowledge of the effect of successive stubble return on cotton yield and nutrient uptake when cotton stubble is incorporated into saline field soil. Hence, a 5-year field study was conducted to investigate the effects of successive stubble management (stubble return and stubble removal) on lint yield and nutrient uptake of cotton, soil nutrients and salinity in the 0–80-cm soil profile. Stubble return increased lint yield by 22.7% and 47.3% in the fourth and fifth year, respectively, mainly through the production of more and larger bolls and the acquisition of more nutrients compared with stubble removal. 5-year cotton stubble return produced 20.0% more bolls and 7.7% larger bolls than stubble removal. Cotton plants accumulated 58.9% more nitrogen (N), 54.5% more phosphorus (P), and 48.2% more potassium (K) under stubble return than stubble removal during the last two years of the experiment. Stubble return increased internal N use efficiency (iNUE) and internal K use efficiency (iKUE) at the fourth or fifth year compared with stubble removal, without influence on internal P use efficiency (iPUE). Stubble return decreased soil pH and salinity in the 0–40-cm soil layer in the fourth and fifth year. The soil nitrate content below the 40-cm soil layer was reduced, while the nitrate concentration in the 0–20-cm soil layer increased after 4 years of stubble return. Available K in the 0–40-cm soil layer increased, while available P in the 0–20-cm soil layer was reduced after 5 years of stubble return. Our analyses demonstrate that cotton stubble return has the potential to improve cotton yield and may be an effective practice to apply in coastal saline areas.

Cotton fibers are single-celled trichomes that differ from the ovule epidermis. As such, they are considered a model system for studying cell elongation and cell wall biogenesis. Fiber development of mutants provide novel materials for dissecting the genetic mechanisms underlying the process. Herein, we described the characteristics and genetics of a new super-short fiber mutant, Ligon-lintless-Sd (LiSd), in upland cotton. The LiSd mutant possesses fuzz, super-short fibers (6–7 mm), normal leaves, and is relatively short plant height. Scanning electron microscopy array revealed no difference in fiber initiation between LiSd and TM-1. Microscopic observations indicated early fiber elongation, which was terminated at 8–13 days post anthesis. The results of genetic analysis revealed that short fiber phenotype was controlled by a single incomplete dominant nuclear gene, named LiSd. The results of allelic analysis in Gossypium hirsutum L. background indicated that LiSd is non-allelic to the previously described shorter fiber mutants Li1, Li2, and is therefore a novel short-fiber mutant gene. The phenotypic characteristics and genetic analyses provide a useful basis for further mapping of this gene and dissecting its molecular mechanisms of fiber elongation and the pleiotropy with plant height in cotton.

Volatile fatty acids (VFAs), which are largely generated during the anaerobic acidification process, are considered to be reliable indicators of the stable process operation. However, the common methods for monitoring VFAs are offline, and they are typically manual requiring time-consuming, costly and complex instruments. This study aims to develop a novel online analyzer for automatic measuring VFAs, which was based on the 5-pH point titration, embedded with a proportional-integral-derivative (PID) feedback control system. The results show that it can achieve accurate and rapid monitoring of VFAs ranging between 0-400 mg/L (9 min/sample) but simultaneously faces the problems of overtitration and interference of complex characteristics of wastewater. In order to improve its accuracy and stability, the effects of three general coefficients (K

In many experiments, a partial nitrification device is initiated with the use of highly active nitrating sludge because of the large number of nitrifying bacteria. Ammonia-oxidizing bacteria (AOB) are more adaptable to low-dissolved oxygen environments than nitrite-oxidizing bacteria (NOB). NOB activity was inhibited when the dissolved oxygen (DO) levels were decreased, causing the nitrate-nitrogen concentration to gradually decrease in the effluent and the nitrite-nitrogen concentration to gradually increase, achieving the accumulation of nitrous nitrogen. In this experiment, a sequencing batch reactor (SBR) was used to suppress NOB activity at a given pH while maintaining DO at a very low level so that the ammonia&ndash, water reaction mainly occurred in the device, and then the mud and water separated. Compared with other experiments, this approach can occur in 25 days, and it runs stably for more than two months until the device closes when the ammonia-nitrogen concentration is about 170 mg/L. This experiment also compared the difference between the pH change at the beginning of the device operation and after the device was stable. In order to increase the efficiency of bacterial appreciation, supplementing NaHCO3 increased the HCO3&minus, concentration by 300 mg/L on the 25th day. It was found that some nitrification reactions still occurred, but they were not enough to destabilize the device. The nitrosate accumulation efficiency still gradually increased, and the average nitrite accumulation efficiency was 87.25% after NaHCO3 supplementation.

Additional file 8: Primer sequences used for qPCR analysis in this study.

Additional file 1: The statistical data of unigenes annotated in public database.

Background Bud dormancy is a sophisticated strategy in which plants evolved to survive in tough environments. Chilling exposure is an effective method to promote dormancy release in perennial plants including tree peony, and endodormancy is a key obstacle for forcing culture of tree peony. However, the mechanism of dormancy release is still poorly understood, and there are few systematic studies on the metabolomics during chilling induced dormancy transition. Results A total of 535 small molecules were obtained in tree peony buds treated with chilling, belonging to flavonoids, amino acid and its derivatives, lipids, organic acids and its derivates, nucleotide and its derivates, alkaloids, hydroxycinnamoyl derivatives, carbohydrates and alcohols, phytohormones, coumarins, and vitamins, respectively. 118 differential metabolites were detected, and they involved in serveral metabolic pathways related to dormancy. Sucrose was the most abundant carbohydrate in peony bud. Starch degradation and EMP activity were enhanced during the dormancy release, according to the variations of sugar contents, related enzyme activities and key genes expression. Flavonoids synthesis and accunmulation were also promoted by prolonged chilling, which might attribute to the activated expression of PsDFR and PsANS. Moreover, the variations of phytohormones (SA, JA, ABA, and IAA) indicated they played different roles in dormancy transition. Conclusion Our study suggested that starch degradation, EMP activation, and flavonoid accumulation were crucial and associated with bud dormancy transition in tree peony.

A novel three-dimensional (3D) carbon nanotube foams (CNTF) with ultrahigh specific surface area have been fabricated through a unique but facile one-step synthesis by using CO2 as both carbon source and activating agent. The activation temperature and time have been adjusted, and the best sample demonstrates a specific surface area of 1959.8 m2 g--1 and a total pore volume of 3.23 cm3 g--1. A reversible capacity of about 870 mAh g--1 is maintained at 50 mA g--1 when the CNTF used as cathode materials. Meanwhile, the capacity is as large as 320 mAh g--1 at the current density of 2 A g--1and the capacity retention is nearly 100% after 500 cycles. These excellent and highly stable battery performances should be attributed to the structural advantages of as-synthesized CNTFs generated by using a facile CO2-assisted strategy, which may potentially be applied in large scale production of porous 3D carbon materials in the fields of energy storage and conversion.

Halogen-free flame retardant tri(acryloyloxyethyl) phosphate (TAEP) optical resin was prepared using hydroxy ethyl acrylate (HEA) and phosphorus oxychloride and the chemical structure was characterized by Fourier transform infrared spectrometer and proton nuclear magnetic resonance spectrometer. Optical resins mixed by pentaerythritol tetrathioglycolic and TAEP with different S and P contents were obtained via click chemistry curing. The curing performance, thermal stability and flame retardant performance of the optical resins were analyzed by differential scanning calorimeter, thermogravimetric analyzer, and vertical burning tester, respectively. Additionally, the burned residual morphology of samples was investigated by scanning electronic microscopy, and the refractive indices of the optical resins were measured by an Abbe refractometer. The results revealed that increasing S content could improve the refractive indices of the resins; whereas, the flame retardant performances decreased. The optical resins with S content of 2% and P contents of 7.37% had refractive indices of 1.4935 and UL 94 V-0 flame retard level, respectively. The optical resins had good thermal stability and the 5% decomposition temperature reached up to 200.1 °C.

A new approach to synthesize fluorine-containing graphene oxide (FCGO) was proposed, in which a less toxic reagent was used rather than fluorine gas or anhydrous hydrogen fluoride. The dielectric and mechanical properties of polyimide composites were improved by incorporating a small amount of FCGO. FCGO served as not only nanofiller to lower the dielectric constant of PI films but also inorganic toughening particles to improve the toughness of PI films. The dielectric constant of PI films with 0.6 wt % FCGO was decreased from 3.33 for pure PI to 2.34. In addition, both the tensile strength and Young’s modulus of PI films with 0.6 wt % FCGO were increased to 141 MPa and 4.95 GPa from 118 MPa and 2.81 GPa for pure PI, respectively. In addition, its tensile energy to break was enhanced to 31.6 MJ/m3 from 20.8 MJ/m3.

Our pilot research revealed that the dielectric constant of polyimide (PI) can be reduced and the modulus can be improved by assembling necklace-like interlocking complexes with crown ethers. Not only did we find that these properties of the PI complex still cannot adequately meet the demand of practical applications but also that there was a deterioration in its thermal stability. A functional octa(aminopropyl)silsesquioxane (OAPrS) with a significantly rigid Si-O-Si cage was incorporated into an 18-crown-6 (CE6)-PI (CE6-PI) complex to produce inorganic-organic OAPrS/CE6-PI nanocomposites. By exploiting the synergetic effect of OAPrS and CE6, most properties of the PI were clearly improved. In the case of 3.9 wt% OAPrS and 7.8 wt% CE6, the dielectric constant of PI was reduced by 30%, and Young's modulus and the tensile strength were increased by 106% and 23%, respectively. In addition, the thermal stability of the CE6-PI complex was modified, and its 5% weight loss temperature and glass transition temperature were increased by 31.2 and 11.2 °C, respectively, with the incorporation of 3.9 wt% OAPrS. The indispensable nano-reinforcing role of aggregated OAPrS crystal in the nanocomposite was carefully analysed and verified.

Low dielectric constant is desired for polyimide to be used in microelectronic industry. In the present study, a series of porous graphene fluoroxide/polyimide (GFO/pPI) nanocomposite films with improved dielectric and mechanical properties were fabricated. Polyethylene glycol (PEG) was introduced into the system to play the roles of an intercalator in exfoliation of graphite fluoroxide and a blowing agent in preparation of porous structure. The in-situ bubble-stretching, resulting from PEG decomposition during the thermal imidization, not only hindered the agglomeration of GFO nanosheets, but also generated micro-pores in PI matrix. Both the porous structure and the GFO nanosheets significantly decreased the dielectric constant of composite films, and the load transfer between GFO and PI matrix efficiently improved the mechanical properties of composite films. A very low dielectric constant of 2.29 as well as high tensile modulus of 4.43 GPa and tensile strength of 159 MPa was obtained for the composite film with the GFO loading of only 0.30 wt%. In addition, the glass transition temperature of GFO/pPI films was increased from 355 °C to 388 °C, and the coefficient of linear thermal expansion of GFO/pPI films was decreased from 48.7 ppm/K to 24.9 ppm/K. Keywords: Polyimide, Graphene fluoroxide, Micropores, Dielectric property, Mechanical properties

Additional file 7: Figure S2. Venn diagram of 4 comparative metabolites. (a) up-regulated metabolites. (b) down-regulated metabolites.