Search

Liriope spicata is an evergreen perennial ornamental groundcover with a strong freezing tolerance. However, the molecular mechanism underlying the freezing tolerance in L. spicata remains unclear. In this study, a comprehensive investigation of L. spicata freezing tolerance was conducted at the levels of physiology and biochemistry, metabolite, and transcript during the stress treatment. There were 581 unique differentially expressed metabolites (DEMs) and 10,444 unique differentially expressed genes (DEGs) between freezing treatment and normal cultured plant in leaves. Integrated analysis of metabolomics and transcriptomics showed that flavonoid biosynthesis, carbohydrate metabolism, amino acid metabolism, lipid metabolism, and signal transduction pathways were prominently enriched in response to the freezing stress in L. spicata. Now, we identified genes and metabolites involved in the flavonoid pathway, abscisic acid (ABA) biosynthesis, and the oxidative synthesis pathway of nitric oxide (NO), which may form a regulatory network and play a synergistic effect in osmotic adjustment, reactive oxygen species (ROS) homeostasis, and stomatal closure under freezing stress. These results offer a comprehensive network of flavonoids, ABA, and NO comodulating the freezing tolerance in L. spicata.

Senescence is an internally systematized degeneration process leading to death in plants. Leaf yellowing, one of the most prominent features of plant aging may lead to reduced crop yields. The molecular mechanism of responses to senescence in soybean leaves is not completely clear. In our research, two soybean varieties were selected with different stay-green traits: stay-green variety (BN106) and non-stay-green variety (KF14). RNA samples extracted from the leaves of two varieties were sequenced and compared using high-throughput sequencing. Six key enzyme genes in chlorophyll degradation pathways were studied to analyze the changes in their expression at seedling, flowering and maturation stage. Meanwhile, the construction of the genetic transformation process had been constructed to identify the function of putative gene by RNA-interference. A total of 4329 DEGs were involved in 52 functional groups and 254 KEGG pathways. Twelve genes encoding senescence-associated and inducible chloroplast stay-green protein showed significant differential expression. MDCase and PAO have a significant expression in BN106 that may be the key factors affecting the maintenance of green characteristics. In addition, the function of GmSGRs has been identified by genetic transformation. The loss of GmSGRs may cause soybean seeds to change from yellow to green. In summary, our results revealed fundamental information about the molecular mechanism of aging in soybeans with different stay-green characteristics. The work of genetic transformation lays a foundation for putative gene function studies that could contribute to postpone aging in soybeans.

We isolated bacteria from the phycosphere of Scenedesmus obliques and sequenced 16S rDNAs to establish algae-bacterial co-culture systems. Further, we examined effects of the bacteria on algal growth, and parameters associated with physio-biochemical and oil-producing characteristics of S. obliquus. Seven bacterial strains were isolated, including Micrococcus (strains 1-1, 1-2 and 1-3), Pseudomonas sp. (strains 2-1 and 2-2), Exiguobacterium (strain-3) and Staphylococcus sp. (strain-4). Among them, two bacteria (strain 1-2 and strain 2-1) were characterized as the dominant growth-promoting bacterial strains, which significantly increased algal growth, pigment production, and oil enrichment. After eight days cultivation under microalgal-bacterial (strain 1-2) symbiotic systemat at an initial ratio of 1:10, biomass of S. obliquus was 4.27 g·L从斜生栅藻藻际分离共生菌群并进行16S rDNA序列鉴定,构建藻菌共培养体系,并检测斜生栅藻生长、生理生化及产油特性。共分离出7个菌群/株,包括微球菌(菌株1-1、1-2和1-3)、假单胞菌(菌株2-1和2-2)、微小杆菌(菌株-3)和葡萄球菌(菌株-4)。微球菌(菌株1-2)和假单胞菌(菌株2-1)为优势促生菌株,能显著促进微藻生长及色素和油脂积累。斜生栅藻与微球菌(菌株1-2)1∶10共培养体系培养8 d后,栅藻生物量高达4.27 g·L

Stress associated proteins (SAPs) are the A20/AN1 zinc-finger proteins which confer to abiotic stresses in plants. In this study, TaSAP7-B, including two AN1 domains, was isolated from B genome of wheat (Triticum aestivum L.). Sequencing analysis on TaSAP7-B illustrated one InDel (insertion-deletion) and one SNP (single nucleotide polymorphism) in the promoter region while no diversity was observed in the coding region. On the basis of SNP in the promoter region (–260 bp), a dCAPS (derived cleaved amplified polymorphic sequences) marker SNP-260 was developed for TaSAP7-B. Using a natural population consisting of 262 wheat accessions, significant associations were detected between the marker SNP-260 and agronomic traits, such as plant height (PH), peduncle length (PL), length of penultimate internode (LPI), number of spike per plant (NSP), and 1 000-grain weight (TGW). Two genotypes were identified using marker SNP-260 in the natural population. Among them, the genotypes possessing C allele exhibited a higher TGW and shorter PH than the T genotypes. Hence, base C was considered as the superior allele. The dCAPS marker of TaSAP7-B can be instrumental for marker-assisted selection for high grain size and short plant height.

Fructans are major nonstructural carbohydrates in wheat (Triticum aestivum L.). Fructan 1-fructosyltransferase (1-FFT) is the key enzyme in fructan biosynthesis. In the present study, 96 sequence variants were detected in the 1-FFT-A1 gene among 26 wheat accessions including UR208, and 15 of them result in amino acid substitutions, forming four haplotypes. Two markers M39 and M2164 were developed based on the InDel21-39 and SNP-2164 polymorphisms to distinguish the three haplotypes in the 1-FFT-A1. 1-FFT-A1 was located on chromosome 4A using marker M2164 and was flanked by markers Xcwm27 and 6-SFT-A1. By association analysis using a natural wheat population consisted of 154 accessions, the results showed that the two markers were significantly associated with water-soluble carbohydrate (WSC) content in the lower internode stem and total stem at the early and middle grain filling stages, 1000-grain weight (TGW) at different grain filling stages and peduncle length (PLE). Comparison of the effects of three haplotypes on agronomic traits indicated that TGW, PLE and total number of spikelets per spike (TNSS) were significantly influenced by haplotypes. HapIII showed a significant positive effect on TGW, PLE and TNSS.

The arbuscular mycorrhizal symbiosis can alleviate salt stress in plants by altering strigolactone levels in the host plant. The aim of this study was to investigate the mechanism by which strigolactones enhance salt stress tolerance in arbuscular mycorrhizal Sesbania cannabina seedlings. Strigolactone levels, as determined by means of germination bioassay, gradually increased with treatment time of NaCl applied. Inhibition of NADPH oxidase activity and chemical scavenging of H2O2 significantly reduced strigolactone-induced salt tolerance and decreased strigolactone levels. The H2O2-induced strigolactone accumulation was accompanied by increased tolerance to salt stress. These results strongly indicated that elevated H2O2 concentration resulting from enhanced NADPH oxidase activity regulated strigolactone-induced salt stress tolerance in arbuscular mycorrhizal S. cannabina seedlings.

Gas explosions causing heavy casualties in the goaf of coal mine occasionally occurred in China. The goaf in the coal mine is a multi-scale complex medium with pores in remaining coal, the gaps among rock blocks that don’t meet the characteristics of the porous medium. The propagation of flames and shock waves induced by the gas explosion in the goaf is very complicated. Based on the spatial structure characteristics of the goaf, the numerical model of a gas explosion is established by using the OpenFOAM open-source CFD source code. The flame and shock wave propagation characteristics induced by the gas explosion are analyzed under the conditions of different arrangements for gradient diameter rocks. The results reveal that the initial flame propagation speed, shock wave and the pressure rise speed all increases firstly, while the values show a decreasing trend when the diameter of the rocks increases in the gradient rocks diameter model. The research results will be of great guiding significance for the prevention and control of gas explosions in the goaf, and the investigation of gas explosion accidents.

Methane explosion pressure characteristics under the condition of different temperatures (25°C-200 °C) were studied by the special environment 20L explosion characteristics test system. By the experimental results, in the case of other conditions unchanged, with the increase of environmental temperature, the maximum explosion pressure of the optimum explosion concentration decrease, the maximum explosion pressure and the reciprocal of environmental temperature show linear attenuation law, the maximum pressure rise rate is not influenced by environmental temperature basically; Outside the scope of explosion limits at normal temperature and pressure, with the increase of environmental temperature, no explosion methane-air mixture are explosive gradually, the maximum explosion pressure and maximum pressure rise rate are in the relationship of different exponential growth with the increase of ambient temperature. The conclusions provide an important theoretical basis for prevent mine gas explosion accidents and coal bed methane safely use.

Novel hierarchical NiCo2O4 nanosheets@hollow microrod arrays (NSs@HMRAs) are fabricated by a simple and environmental friendly template-assisted electrodeposition followed by thermal annealing. Due to their unique nanostructures, the NiCo2O4 NSs@HMRAs, as electrodes, exhibited a high specific capacitance (Csp) (678 F g−1 at 6 A g−1) and outstanding cycle stability (Csp retention of 96.06% after 1500 cycles). The desirable superior capacitive performance of the NiCo2O4 NSs@HMRAs can be attributed to the large specific surface area, fast ion diffusion, and perfect charge transmission in the hierarchical NSs@HMRAs. The asymmetric supercapacitor (ASC) based on the NiCo2O4 NSs@HMRAs as a positive electrode and active carbon (AC) as a negative electrode was assembled and it exhibited a Csp of 70.04 F g−1 at 5 mV s−1 and a high energy density of 15.42 W h kg−1. Moreover, the NiCo2O4 NSs@HMRAs//AC ASC has an outstanding cycle stability (almost no Csp loss after 2500 cycles), making it promising as one of the most attractive candidates for electrochemical energy storage.

In this paper, we study on the problem of how to combine feature selection models in text classification ,and present a method through build the hybrid model for feature selection ,this hybrid model combined with advantage of four feature selection models (DF,MI, IG, CHI), then we use the Naive Bayes model as classifier to verify the effect of the hybrid feature selelction model ,and experiments shows that the hybrid model is correct and effective and get good performance in text classification.

Gly m Bd 28K, Gly m Bd 30K and Gly m Bd 60K are the major soybean (Glycine max (L.) Merr.) allergens limiting the consumption of a good protein source for sensitive individuals. However, little is known about their temporal-spatial expression during seed development and upon germination. The present data shows that soy allergens accumulated in both the embryonic axes and cotyledon, but expression patterns differed depending on the specific allergen. Allergens accumulated sooner and to a greater level in cotyledons than in embryonic axes. Gly m Bd 28 began at 14 d after flowering, 7 to 14 d earlier than Gly m Bd 30K and Gly m Bd 60K. Comparatively, their degradation was faster and more profound in embryonic axes than in cotyledons. Gly m Bd 60K began to decline at 36 h after imbibition and remained detectable up to 108 h in cotyledons. In contrast, the Glym Bd 60K protein was reduced at 24 h, and eventually disappeared at 96 h . In cotyledons Gly m Bd 28K first declined at 24 h, then increased from 36 h to 48 h, followed by its large reduction at 72 h after seed germination. These findings provide useful information on soy allergen biosynthesis and will help move forward towards developing a hypoallergenic soybean for safer food.

研究分子标记鉴定大麦抗黄矮病基因 Yd2 的有效性，可为 Yd2 基因在大麦抗病育种中的广泛应用提供快速有效的分子辅助选择工具。利用与 Yd2 基因紧密连锁的 YLM 、 CAPS-Ylp 和 ASPCR-Ylp 标记同时检测52份国内外大麦品种(系)与4份大麦F 1 杂种的 Yd2 基因型，同时结合生物学抗性检测的表型分析其有效性。通过对 Yd2 基因型已知的20份大麦品种(系)及4个F 1 杂种的 Yd2 基因型分析，表明 YLM 、 CAPS-Ylp 与 ASPCR-Ylp 标记可以有效判断大麦 Yd2 基因型。进一步用这3个标记检测32份 Yd2 基因型未知的大麦的基因型，鉴定出基因型为 Yd2 - / Yd2 - 的品种(系) 27份，基因型为 Yd2 + / Yd2 + 的品种(系) 5份。在回交育种的分子辅助选择实例中，从BC 2 F 2 世代中选出了16个基因型为 Yd2 + / Yd2 + 的单株。3个分子标记结合应用能够快速有效地鉴定大麦 Yd2 基因型，可用于 Yd2 基因回交育种中的大规模分子标记辅助选择。

The experiment of gas and coal dust explosion propagation in a single laneway was carried out in a large experimental roadway that is nearly the same with actual environment and geometry conditions. In the experiment, the time when the gas and coal dust explosion flame reaches test points has a logarithmic function relation with the test point distances. The explosion flame propagation velocity rises rapidly in the foreside of the coal dust segment and comes down after that. The length of the flame area is about 2 times that of the original coal dust accumulation area. Shock wave pressure comes down to the rock bottom in the coal dust segment, then reaches the maximum peak rapidly and comes down. The theoretical basis of the research and assemble of across or explosion is supplied by the experiment conclusion. Compared with gas explosion, the force and destruction degree of gas and coal dust explosion is much larger.

Plastid gene engineering has become a new way for plant genetic improvements, particularly showing a unique application value in the use of plants as reactors to produce biopharmaceuticals and other important organic compounds. However, plastids only have a semi-autonomous transcription and translation machinery. The transcription of endogenous plastid genes is largely dependent on nuclear-encoded transcription factors. Regulation of foreign gene expression in plastids is influenced by various factors. Several technique strategies for regulation of transgene expression in plastids were reported recently, such as hybrid transcription factor-mediated system, phage T7-based transcription system and bacterial lac suppressor-based system. The application and improvement of these systems will greatly enhance the specific and effective expression of the transgenes, and achieve high-level accumulations of foreign proteins in plastids.

Plant seed oil is the major source of many fatty acids for human nutrition, and also one of industrial feedstocks. Recent advances in understanding of the basic biochemistry of seed oil biosynthesis, coupled with cloning of the genes encoding the enzymes involved in fatty acid modification and oil accumulation, have set the stage for the metabolic engineering of oilseed crops that produce "designer" plant seed oils with the improved nutritional values for human being. In this review we provide an overview of seed oil biosynthesis/regulation and highlight the key enzymatic steps that are targets for gene manipulation. The strategies of metabolic engineering of fatty acids in oilseeds, including overexpression or suppression of genes encoding single or multi-step biosynthetic pathways and assembling the complete pathway for the synthesis of long-chain polyunsaturated fatty acids (e.g. arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid) are described in detail. The current "bottlenecks" in using common oilseeds as "bioreactors" for commercial production of high-value fatty acids are analyzed. It is also discussed that the future research focuses of oilseed metabolic engineering and the prospects in creating renewable sources and promoting the sustainable development of human society and economy.

Plastid gene engineering has become a new way for plant genetic improvements, particularly showing a unique application value in the use of plants as reactors to produce biopharmaceuticals and other important organic compounds. However, plastids only have a semi-autonomous transcription and translation machinery. The transcription of endogenous plastid genes is largely dependent on nuclear-encoded transcription factors. Regulation of foreign gene expression in plastids is influenced by various factors. Several technique strategies for regulation of transgene expression in plastids were reported recently, such as hybrid transcription factor-mediated system, phage T7-based transcription system and bacterial lac suppressor-based system. The application and improvement of these systems will greatly enhance the specific and effective expression of the transgenes, and achieve high-level accumulations of foreign proteins in plastids.

The most nutrients required in the human diet come from plants. The nutritional quality of plant products affects the human healthy. The advance of molecular cloning and transgenic technology has provided a new way to enhance the nutritional value of plant material. Transgenic modification of plant nutritional value has progressed greatly in the following aspects: improving the quality, composition and levels of protein, starch and fatty acid in different crops; increasing the levels of antioxidants (e.g. carotenoids and flavonoids); breeding the new type of plants with medical value for human. To date, many transgenic plants with nutritional enhancement have been developed. These transgenic plant products could be directly used as human diet or as valued materials in developing the "functional food" with especial nutritional quality and healthy effects after they are approved by a series of evaluations on their safety and nutritional efficiency for human being. We designed new zinc finger transcription factors (ZFP-TFs) that can specifically down-regulate the expression of the endogenous soybean FAD2-1 gene which catalyzes oleic acid to linoleic acid. Seed-specific expression of these ZFP-TFs in transgenic soybean somatic embryos repressed FAD2-1 transcription and increased significantly the levels of oleic acid, indicating that the engineered ZFP-TFs are capable of regulating fatty acid metabolism and modulating the expression of endogenous genes in plants.

Heavy metal pollution has become a global environmental hazard. The use of microorganisms and plants for the decontamination of heavy metals is recognized as a low lost and high efficiency method for cleaning up metal contamination. It shows that various metal-binding proteins such as metallothioneins (MTs) or phytochelatines (PCs) play an important role in defense systems and detoxification to heavy metals in organisms. Many genes of MTs and PCs have been cloned and utilized successfully in genetically modified bacteria and plants for increasing remediation capacity. These transgenic organisms have been displayed a great potential in bioremediation and phytoremediation of heavy metals.

Secondary metabolism plays an important role in plant life as well as the interaction between plants and environmental factors. Many secondary metabolites derived from plants have been used for the production of medicines, dyes, insecticides, food flavors, fragrances and so on. With increasingly comprehensive understanding of the plant metabolic networks, great progress has been made in the genetic improvement of plant secondary metabolic pathways through gene engineering. Strategies for the genetic engineering of plant secondary metabolism include: (1) enabling the host plant to accumulate a novel desirable compound by transformation of single/multiple enzyme gene (s) or a whole metabolic pathway; (2) decreasing target gene expression or inhibiting competitive metabolic pathway to achieve metabolic flux towards higher production of particular molecules through antisense RNA and RNA interference technologies; (3) effectively manipulating the transcription factors responsible for the metabolic regulation at multiple steps in a given pathway so as to have a great synthesis of the target bio-chemicals. Basing on author's research work on flavonoid synthesis mechanism in soybean seed and its gene engineering, recent progress in the engineering of plant secondary metabolism involved in the synthesis of anthocyanins, flavonoids, alkaloids, terpenoids, benzoic acid derivatives etc are reviewed.

Single nucleotide polymorphism(SNP) is the most common type of sequence difference between alleles, which can be used as a kind of high-throughput genetic marker. Several different routes have been developed to discover and identify SNP. These include the direct sequencing of PCR amplicons, electronic SNP(eSNP) and so on. SNP assays have been made in many crop species such as maize and soybean. The elite germplasm of some crops have been narrowed in genetic diversity, increasing the amount of linkage disequilibrium (LD) present and facilitating the association of SNP haplotypes at candidate gene loci with phenotypes. SNP analysis has been broadly used in the field of plant gene mapping, integration of genetic and physical maps, DNA marker-assisted breeding and functional genomics.

To detect quantitative trait loci (QTLs) controlling plant height, the plant height of 240 F2:3 lines derived from the cross of a dwarf wheat line ND3338 with a tall line F390, was assessed in field trials at two locations with three replications in 2000 and 2001. Microsatellite markers were used to construct a framework linkage map containing 215 loci with 21 linkage groups, and covering the whole genome about 3600cM. With the method of interval mapping, seven putative QTLs affecting plant height were detected on chromosomes 1B, 4B (two regions), 6A (two regions), 6D and 7A, respectively. Phenotypic variations explained by each QTL ranged from 5.2% to 50.1%, and in each environment the total putative QTLs explained about 64.8%-75% of the total phenotypic variation respectively. A major QTL located on chromosome arm 4BS near the locus Xgwm113, around the Rht-Blb locus, explained a large part of the phenotypic variation (27.8%-36.2% depending on the years or the locations). Except the QTL on chromosome 7A, all the other QTLs from ND3338 decreased the plant height, variously from 0.94 cm to 9.33 cm. Most of the identified QTLs were consistent in all the environments, and should be useful in future marker-assisted-selection programs for breeding dwarf and semi-dwarf wheat cultivars.

Platelet-activating factor (PAF) is a potent lipid mediator of inflammation and asthma. Using a receptor preparation of rabbit platelet membranes, we identified a novel antagonist of PAF in the methylene chloride extract of a Chinese herbal plant, haifenteng (Piper futokadsura). The active antagonist, kadsurenone, was isolated and characterized in several in vitro and in vivo assays. It is a specific and competitive inhibitor of PAF binding to its receptor with a Ki of 5.8 X 10(-8) M vs. a Ki of 6.3 X 10(-9) M for PAF itself. It inhibits PAF-induced aggregation of rabbit platelets and human neutrophils at 2.4-24 microM, without showing any PAF agonistic activity. It potently inhibits PAF-induced degranulation of human neutrophils at 2.5-50 microM, also without any agonist activity. Kadsurenone is active orally at 25-50 mg/kg of body weight in blocking PAF-induced cutaneous permeability in the guinea pig. It also inhibits PAF-induced increases of hematocrit and circulating N-acetylglucosaminidase in the rat at greater than 10 mg/kg i.p. in a dose-dependent manner. Kadsurenone does not interfere with the function of several pharmacological mediators and receptors tested. Its structural specificity is evidenced by the poor PAF-antagonistic activities of three related structures isolated from the same haifenteng extract.