BackgroundThe sinorhizobia are amongst the most well studied members of nitrogen-fixing root nodule bacteria and contribute substantial amounts of fixed nitrogen to the biosphere. While the alfalfa symbiont Sinorhizobium meliloti RM 1021 was one of the first rhizobial strains to be completely sequenced, little information is available about the genomes of this large and diverse species group.ResultsHere we report the draft assembly and annotation of 48 strains of Sinorhizobium comprising five genospecies. While S. meliloti and S. medicae are taxonomically related, they displayed different nodulation patterns on diverse Medicago host plants, and have differences in gene content, including those involved in conjugation and organic sulfur utilization. Genes involved in Nod factor and polysaccharide biosynthesis, denitrification and type III, IV, and VI secretion systems also vary within and between species. Symbiotic phenotyping and mutational analyses indicated that some type IV secretion genes are symbiosis-related and involved in nitrogen fixation efficiency. Moreover, there is a correlation between the presence of type IV secretion systems, heme biosynthesis and microaerobic denitrification genes, and symbiotic efficiency.ConclusionsOur results suggest that each Sinorhizobium strain uses a slightly different strategy to obtain maximum compatibility with a host plant. This large genome data set provides useful information to better understand the functional features of five Sinorhizobium species, especially compatibility in legume-Sinorhizobium interactions. The diversity of genes present in the accessory genomes of members of this genus indicates that each bacterium has adopted slightly different strategies to interact with diverse plant genera and soil environments.

Yellow seed is a desirable trait with great potential for improving seed quality in Brassica crops. Unfortunately, no natural or induced yellow seed germplasms have been found in Brassica napus, an important oil crop, which likely reflects its genome complexity and the difficulty of the simultaneous random mutagenesis of multiple gene copies with functional redundancy. Here, we demonstrate the first application of CRISPR/Cas9 for creating yellow‐seeded mutants in rapeseed. The targeted mutations of the BnTT8 gene were stably transmitted to successive generations, and a range of homozygous mutants with loss‐of‐function alleles of the target genes were obtained for phenotyping. The yellow‐seeded phenotype could be recovered only in targeted mutants of both BnTT8 functional copies, indicating that the redundant roles of BnA09.TT8 and BnC09.TT8b are vital for seed colour. The BnTT8 double mutants produced seeds with elevated seed oil and protein content and altered fatty acid (FA) composition without any serious defects in the yield‐related traits, making it a valuable resource for rapeseed breeding programmes. Chemical staining and histological analysis showed that the targeted mutations of BnTT8 completely blocked the proanthocyanidin (PA)‐specific deposition in the seed coat. Further, transcriptomic profiling revealed that the targeted mutations of BnTT8 resulted in the broad suppression of phenylpropanoid/flavonoid biosynthesis genes, which indicated a much more complex molecular mechanism underlying seed colour formation in rapeseed than in Arabidopsis and other Brassica species. In addition, gene expression analysis revealed the possible mechanism through which BnTT8 altered the oil content and fatty acid composition in seeds.

Both high visible transparency and strong solar modulating ability are highly required for energy-saving smart windows, but conventional responsive materials usually have low transparency and narrow solar transmittance range. Herein,...

In North America, the operation of buildings accounts for approximately one third of the total energy use and greenhouse gas emissions annually. Office buildings are responsible for roughly 35% of the total commercial/institutional secondary energy use in Canada, followed by retail buildings at 17% (NRCan, OEE, 2010).In recent years, a number of researchers from around the world have conducted life-cycle assessment (LCA) studies to investigate the impacts of buildings on the environment. Most studies have focused on three types of buildings: office buildings, single residential dwellings, and multi-unit residential apartments. There have been almost no comprehensive LCA studies of retail buildings, specifically single-storey retail buildings. This is a problem, since compared to office buildings, single residential dwellings, and multi-unit residential apartments, retail buildings consume approximately 1.2, 2.0, and 2.3 times more energy per floor area respectively (NRCan, OEE, 2010). In addition, retail buildings usually undergo major resource intensive renovations far sooner than other building types. Therefore, the primary goal of this study was to conduct a comprehensive LCA for the components of a singlestorey retail building located in Toronto, Canada, to determine which building components contribute the most towards the total life-cycle energy use and global warming potential (GWP) after 50 years.Using the latest LCA techniques, the total life-cycle energy use and GWP was calculated for 220 different building components including: exterior infill walls, roofs, structural systems, floors, windows, doors, foundations, and interior partition walls. Also, a comprehensive LCA study was conducted for five single-storey retail buildings (including a pre-engineered steel building system which is lacking in the literature), in order to determine which components of a single-storey retail building are responsible for the most environmental damage.For a typical single-storey retail building located in Toronto, Canada, the operating energy (and GWP) accounts for about 91% (88%) and the total embodied energy (and GWP) accounts for about 9% (12%) of the total energy (and GWP) after 50 years. The roof alone is responsible for nearly half of the total embodied energy and GWP of the entire building. The LCA study also found that after 50 years, the total energy (and GWP) of the five case study buildings only differed at most by 6% (7%), regardless of the choice of structural system, or whether the building was made predominately of steel or wood building components. This thesis concludes with a prioritized list of recommendations for reducing the total life-cycle energy use and GWP of a single-storey retail building in Canada.iv

Seed dormancy (SD) is controlled by its own complicated genetic factors and environmental factors. SD is an important trait affecting grain yield and quality in cereal crops. A population comprising 240 recombinant inbred lines (RIL) was used for detecting quantitative trait locus (QTL) for SD in rice. To minimize the effect of environment, data for lines for which the optimum temperature during the late ripening stage is either below 20°C or above 30°C were excluded from the analysis, which left 185 lines. In a dynamic germination test of the parents of the population, Minghui 63 showed clear SD and Zhenshan 97 showed none. The seeds of each RIL, harvested 32 days after heading, were divided into two lots: seeds in one lot were sown immediately, without any treatment to break their dormancy, whereas seeds in the other lot were sown after they had been exposed to dry heat (50°C) for 72 h. Composite interval mapping showed the presence of qDGE1, qDGR5a, qDGR5b, and qDGR7 in the first lot whereas only qDGR7 was detected in the second lot--which had been treated to break SD--indicating the strong influence of qDGR7 in controlling SD.A recently cloned Sdr4 is also located in the qDGR7 region. Coincidently, three rice homologues of Arabidopsis SD gene DOG1 were found in qDGE1 and qDGR5b regions where no SD QTL had been reported so far. These results indicate that the QTL found in this study are reliable, and that it would be worthwhile to clone qDGE1 and qDGR5b.

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Biologically inspired superstructural materials exhibit wide application prospects in many fields, in terms of mitigating increasingly serious electromagnetic (EM) pollution in the civil field. Here, we successfully obtain bamboo slices with uniform pore size distribution through the advanced bamboo transverse splitting technology developed by our group previously and prepare large-scale honeycomb-like carbon-based tubular array (CTA) structures with a controllable pore size, graphitization degree, and selectable conductivity property. Based on the simulation and experimental results, the EM shielding performance of CTAs is proven to be sensitive to the microchannel aperture size and the EM energy incident angle, which is attributed to the difference in the propagation rate of induced electrons in different directions. Among the candidates, CTA-middle-1500 exhibits the best shielding performance against incident EM energy with average SE/ρ values of 123.7 and 144.5 dB cm3 g–1 for perpendicular and parallel directions, respectively, showing its application potential as a lightweight and efficient EM shielding material. The predicted optimal incident angle for CTA-middle-1500 against EM energy radiation is 15°, with the largest RCS reduction value of 26.1 dB m2. The excellent EM shielding performance is attributed to the good reflection capacity involved with the high conductivities of the CTAs.

Developing advanced electrode materials with highly improved charge and mass transfer is critical to obtain high specific capacities and long-term cycle life for energy storage. Herein, three-dimensionally (3D) porous network electrodes with Cu(OH) 2 nanosheets/Ni 3 S 2 nanowire 2D/1D heterostructures are rationally fabricated. Different from traditional surface deposition, the 1D/2D heterostructure network is obtained by in situ hydrothermal chemical etching of the surface layer of nickel foam (NF) ligaments. The Cu(OH) 2 /Ni 3 S 2 @NF electrode delivers a high specific capacity (1855 F g –1 at 2 mA cm –2 ) together with a remarkable stability. The capacity retention of the electrode is over 110% after 35,000 charge/discharge cycles at 20 mA cm –2 . The improved performance is attributed to the enhanced electron transfer between 1D Ni 3 S 2 and 2D Cu(OH) 2 , highly accessible sites of 3D network for electrolyte ions, and strong mechanical bonding and good electrical connection between Cu(OH) 2 /Ni 3 S 2 active materials and the conductive NF. Especially, the unique 1D/2D heterostructure alleviates structural pulverization during the ion insertion/desertion process. A symmetric device applying the Cu(OH) 2 /Ni 3 S 2 @NF electrode exhibits a remarkable cycling stability with the capacitance retention maintaining over 98% after 30,000 cycles at 50 mA cm –2 . Therefore, the outstanding performance promises the architectural 1D/2D heterostructure to offer potential applications in future electrochemical energy storage.