Assessment of molecular markers and marker-assisted selection for drought tolerance in barley(Hordeum vulgare L.)

This review updates the present status of the field of molecular markers and marker-assisted selection(MAS),using the example of drought tolerance in barley.The accuracy of selected quantitative trait loci(QTLs),candidate genes and suggested markers was assessed in the barley genome cv.Morex.Six common strategies are described for molecular marker development,candidate gene identification and verification,and their possible applications in MAS to improve the grain yield and yield components in barley under drought stress.These strategies are based on the following five principles:(1)Molecular markers are designated as genomic‘tags’,and their‘prediction’is strongly dependent on their distance from a candidate gene on genetic or physical maps;(2)plants react differently under favourable and stressful conditions or depending on their stage of development;(3)each candidate gene must be verified by confirming its expression in the relevant conditions,e.g.,drought;(4)the molecular marker identified must be validated for MAS for tolerance to drought stress and improved grain yield;and(5)the small number of molecular markers realized for MAS in breeding,from among the many studies targeting candidate genes,can be explained by the complex nature of drought stress,and multiple stress-responsive genes in each barley genotype that are expressed differentially depending on many other factors.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

Molecular engineering binuclear copper catalysts for selective CO_(2) reduction to C_(2) products

Molecular copper catalysts serve as exemplary models for correlating the structure-reaction-mechanism relationship in the electrochemical CO_(2) reduction(eCO_(2)R),owing to their adaptable environments surrounding the copper metal centres.This investigation,employing density functional theory calculations,focuses on a novel family of binuclear Cu molecular catalysts.The modulation of their coordination configuration through the introduction of organic groups aims to assess their efficacy in converting CO_(2) to C_(2)products.Our findings highlight the crucial role of chemical valence state in shaping the characteristics of binuclear Cu catalysts,consequently influencing the eCO_(2)R behaviour,Notably,the Cu(Ⅱ)Cu(Ⅱ)macrocycle catalyst exhibits enhanced suppression of the hydrogen evolution reaction(HER),facilitating proton trans fer and the eCO_(2)R process.Fu rthermore,we explo re the impact of diverse electro n-withdrawing and electron-donating groups coordinated to the macrocycle(R=-F,-H,and-OCH_3)on the electron distribution in the molecular catalysts.Strategic placement of-OCH_3 groups in the macrocycles leads to a favourable oxidation state of the Cu centres and subsequent C-C coupling to form C_(2) products.This research provides fundamental insights into the design and optimization of binuclear Cu molecular catalysts for the electrochemical conversion of CO_(2) to value-added C_(2) products.

Improvement of Resistance to Rice Blast in Zhenshan 97 by Molecular Marker-aided Selection

Fungi blast is one of the most serious diseases of rice worldwide. Breeding resistant varieties have been proved to be the most effective and economical means to control the disease. This paper describes the molecular marker-assisted selection (MAS) procedure for a broad-spectrum blast resistant gene Pi1 integrated into an elite hybrid maintainer line, Zhenshan 97. A simple sequence repeat (SSR) based on molecular marker-aided selection system for Pi1 segment was established. Using a backcross population and a blast isolate F1829, Pi1 gene was mapped on the top of chromosome 11 between markers RZ536 and RM144, with a distance of 9.7 cM and 6.8 cM, respectively. Seventeen families derived from the recurrent parent Zhenshan 97 were obtained with homozygous Pi1 gene. The background of the 17 families was identified with inter simple sequence repeat (ISSR) amplification, the highest recovery of the Zhenshan 97 genetic background was 97.01% after the assay of 167 polymorphic bands.

Molecular Marker Assisted Selection for Fusarium Wilt Resistance Breeding in Watermelon(Citrullus lanatus)

Molecular identification on diploid and tetraploid watermelon breeding lines which were resistant to Fusarium wilt was carried out with the published dCAPS marker ＂4451_fon＂ which was closely linked with resistance gene of Fusarium wilt race 1. The results showed that all the diploid and tetraploid lines expressed as re- sistant genotype, which were defined as Fusarium wilt-resistant materials. The re- sults were consistent with that of artificial inoculation identification. Molecular identifi- cation results also indicated that the resistant lines were homozygote, and the Fusarium wilt-resistant gene would not separate or lose during the future self- crossed purification. Therefore, resistance selection would not be necessary in their progeny populations. The study results thought that dCAPS marker ＂4451_fon＂ could be applied on molecular marker assisted selection for Fusarium wilt resistance breeding in watermelon to increase breeding selection efficiency and accelerate breeding progress.

Molecular Marker Assisted Selection for Yield-Enhancing Genes in the Progeny of Minghui63 x O. rufipogon

Two yield-enhancing genes (yld1.1 and yld2.1) are located on chromosomes 1 and 2 respectivelyin a weedy relative of cultivated rice, Oryza rufipogon. SSR markers RM9 and RM166 are closelylinked with the two loci respectively. Minghui63 (MH63) has been a widely used restorationline in hybrid rice production in China during the past two decades. The F1 of cross 'MH63O.rufipogon' was backcrossed with MH63 generation by generation. RM9 and RM166 were used toselect the plants from the progeny of the backcross populations. The results were as follows:(1) In BC2F1 population, the percentage of the individuals which have RM9 and RM166 amplifiedbands simultaneously was 12.2%, while in the BC3F1 population, that was 16.3%. (2) Among 400individuals of BC3F1, four yield-promising plants were obtained, with yield being 30% more thanthat of MH63. (3) The products amplified by primer RM166 in O. rufipogon and MH63 weresequenced. It was found that the DNA fragment sequence amplified by RM166 from MH63 was 101 bpshorter than that from O. rufipogon. The 101bp sequence is a part of an intron of the PCNA(proliferating cell nuclear antigen) gene.

Application of Molecular Markers Linking to Cytoplasmic Male Sterile Loci to Assist Maintainer Line Selection and Their Selection Efficiency in Welsh Onion (Allium fistulosum L.)

Cytoplasmic male sterility exists widely in most natural populations of welsh onion （Alliumfistulosum L.）, which makes it possible to breed out many male sterile lines for heterosis utilization. Unfortunately, the breeding of cytoplasmic male sterility in welsh onion has a little progress due to the limitation of its biological characteristic and traditional selection approach. To study the feasibility and the efficiency of utilizing marker assisted selection for male sterile lines in welsh onion, one SCAR marker, SCS13, and one RAPD marker, S2002400, which could distinguish between N and S cytoplasm in several welsh onion cultivars, were identified. The two markers were then confirmed by Southern blotting, and used to screen the N or S cytoplasm of individual plants in seven welsh onion cultivars in this study. Male sterile and fertile plants were evaluated by aceto-carmine dying. The frequency of N-cytoplasmic plants and maintainer genotype was calculated in the seven open populations of welsh onion. The minimum number of plants needed to identify a maintainer was evaluated to be 95% reliable. Results showed that 20 to 80% decrease of crosses and self-crosses for identifying a maintainer genotype could be achieved by the marker-assisted selection compared with traditional selection method. It was proved that the molecular markers could precisely identify cytoplasmic types individually, performed by one generation of cross and two generations of testcrosses and self-crosses. Finally, several maintainer genotype plants were selected with the help of the two markers in the seven cultivars. The screened markers could assist and accelerate sterile and maintainer lines selection with less labor and cost.

Breeding Rice Restorer Lines with High Resistance to Bacterial Blight by Using Molecular Marker-Assisted Selection

Two bacterial blight （BB） resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, C Ⅰ -CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.

Improving Blast Resistance of a Thermo-Sensitive Genic Male Sterile Rice Line GD-8S by Molecular Marker-Assisted Selection

The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast, by using backcross breeding and molecular marker-assisted selection. Five elite improved male sterile lines, RGD8S-1, RGD8S-2, RGD8S-3, RGD8S-4 and RGD8S-5, were selected based on the results of molecular marker analysis, spikelet sterility, recovery rate of genetic background and agronomic traits. Thirty-three representative blast isolates collected from Guangdong Province, China were used to inoculate the improved lines and the original line GD-8S artificially. The resistance frequencies of the improved lines ranged from 76.47% to 100%, much higher than that of the original line GD-8S （9.09%）. On the agronomic characters, there were no significant differences between the improved lines and GD-8S except for flag leaf length and panicle number per plant. The improved lines could be used for breeding hybrid rice with high blast resistance.

Lowering Grain Amylose Content in Backcross Offsprings of indica Rice Variety 057 by Molecular Marker-Assisted Selection

To lower the amylose content （AC） of the indica rice restorer line 057 with high AC, backcrosses were made respectively by using four indica varieties （R367, 91499, Yanhui 559, Hui 527） as low AC donor parents and 057 as the recurrent parent. A molecular marker （PCR-Acc Ⅰ） was used to identify the genotypes （GG, TT and GT） of the waxy （Wx） gene. Plants with GT genotype were selected and used as female parent and crossed with 057 to advance generation. The ACs of rice grains harvested from plants with different Wx genotypes were measured and compared to analyze the efficiency of marker-assisted selection. The ACs of the rice grain, harvested from the plants of Wx genotypes GG, GT and TT, were higher than 20%, in the range of 17.7-28.5%, and less than 18%, respectively. The PCR-Acc Ⅰ marker could be used for efficiently lowering the AC of 057 through backcrossing, and there were some influence of parental genetic background on the AC of rice grains with the same Wx genotype.

Inheritance of Clubroot Resistance of Miniature Chinese Baby Cabbage and Molecular Markers-assisted Selection

[Objective] The paper was to analyze the inheritance of clubroot resistance of miniature Chinese baby cabbage,to shorten identification time and to improve breeding efficacy of new disease-resistant varieties. [Method] Taking clubroot-resistant Chinese cabbage CCR001,disease-susceptible baby cabbage CM002,and their F_1,F_2 and BC_1 offspring as the research objects,the inheritance of clubroot resistance of baby cabbage was studied. [Result]The clubroot-resistance of baby cabbage was controlled by a single dominant gene,which conformed to Mendel＇s Laws of inheritance. The molecular markers-assisted selection combing with bacterial soil inoculation confirmed that the disease-resistance indeed passed on from the parents,and was inherited in F_1 and F_2. [Conclusion]It is feasible to breed clubroot-resistant baby cabbage by using molecular markers-assisted selection.

Cooling rate dependence of polymorph selection during rapid solidification of liquid metal zinc

The polymorph selection during rapid solidification of zinc melt was investigated by molecular dynamics simulation. Several methods including g（r）, energy, CNS, basic cluster and visualization were used to analyze the results. The results reveal that the cooling rate has no observable effect on the microstructure as TTc（Tc is the onset temperature of crystallization）; and at the first stage of crystallization, although microstructures are different, the morphologies of nucleus are similar, which are composed of HCP and FCC layers; the polymorph selection of cooling rate finally takes place at the second stage of crystallization： at a high cooling rate, the rapid increase of FCC atoms leads to a FCC crystal mixed with less HCP structures; while at a low cooling rate, HCP atoms grow at the expense of FCC atoms, resulting in an almost perfect HCP phase. The results reveal that the cooling rate is one of the important factors for polymorph selection.

Identification of Molecular Markers for a Aphid Resistance Gene in Sorghum and Selective Efficiency Using These Markers

In this study, an F2 segregated population obtained by hybridization between the aphid-sensitive sorghum strain Qiansan and aphid-resistant cultivar Henong 16 was used to establish an aphid-resistant pool and an aphid-sensitive pool. 192 pairs of AFLP （amplified fragment length polymorphism） marker primers were screened in these pools using BSA （bulked segregant analysis）. Three pairs of EcoR I-CTG/Mse I-CCT, EcoR I-CTG/Mse I-CAT, and EcoR I-AGT/Mse I-CCC showed linkage with aphis resistance. EcoR I-CTG/Mse I-CCT-475, EcoR I-CTG/Mse I-CAT-390, and EcoR I-AGT/Mse I-CCC- 350 （E42/M52-350） were mapped within 6, 10, and 13 cM distances with the aphid-resistant gene by using Mapmaker 3.0 software. The bands amplified by EcoR I-CTG/Mse I-CCT-475 and EcoR I-CTG/Mse I-CAT-390 were extracted, cloned, and sequenced. Specific primers of SCAR （sequence characterized amplified regions） were then designed from these bands. A specific band of 300 bp was amplified by a pair of SCAR primers designed based on the sequence obtained from the EcoR I-CTG/Mse I-CAT-390 marker. The SCAR marker was named SCAS0. The marker was used to detect the F2, BC1, and F2：3 populations. The selective efficiency was 86.8, 91.1, and 86.3% in the BC1, F2, and F2：3 populations, respectively. The average selective efficiency was 88.2%.

Ultraselective carbon molecular sieve membrane for hydrogen purification

Hydrogen is a green clean fuel and chemical feedstock. Its separation and purification from hydrogencontaining mixtures is the key step in the production of hydrogen with high purity(>99.99%). In this work, carbon molecular sieve(CMS) membranes with ultrahigh permselectivity for hydrogen purification were fabricated by high-temperature(700–900 ℃) pyrolysis of polymeric precursor of phenolphthaleinbased cardo poly(arylene ether ketone)(PEK-C). The evolution of the microstructural texture and ultramicroporous structure and gas separation performance of the CMS membrane were characterized via TG-MS, FT-IR, XRD, TEM, CO2 sorption analysis and gas permeation measurements. CMS membranes prepared at 700 ℃ exhibited amorphous turbostratic carbon structures and high H2 permeability of 5260 Barrer with H2/CH4, H2/N2 and H2/CO selectivities of 311, 142, 75, respectively. When carbonized at900 ℃, the CMS membrane with ultrahigh H2/CH4 selectivity of 1859 was derived owing to the formation of the dense and ordered carbon structure. CMS membranes with ultrahigh permselectivity exhibit an attractive application prospect in hydrogen purification.

Ce-Doped Smart Adsorbentswith Photoresponsive Molecular Switches for Selective Adsorption and Efficient Desorption

Achieving efficient adsorption and desorption processes by controllably tuning the properties of adsorbents at different technical stages is extremely attractive.However,it is difficult for traditional adsorbents to reach the target because of their fixed active sites.Herein,we report on the fabrication of a smart adsorbent,which was achieved by introducing photoresponsive azobenzene derivatives with cis/trans isomers to Ce-doped mesoporous silica.These photoresponsive groups serve as “molecular switches”by sheltering and exposing active sites,leading to efficient adsorption and desorption.Ce is also doped to provide additional active sites in order to enhance the adsorption performance.The results show that the cis isomers effectively shelter the active sites,leading to the selective adsorption of methylene blue(MB)over brilliant blue(BB),while the trans isomers completely expose the active sites,resulting in the convenient release of the adsorbates.Both selective adsorption and efficient desorption can be realized controllably by these smart adsorbents through photostimulation.Moreover,the performance of the obtained materials is well maintained after five cycles.

Pyramiding Breeding by Marker-Assisted Recurrent Selection in Upland Cotton: Selected Effects on Resistance to Helicoverpa armigera

The coincidence rates were more than 96% among the instar-weighted average of bioassaysin the lab, the percentage of resistance to Km in the field and the percentage of plantscontaining Bt gene. So, the performance of resistance to Km in the field can be used torepresent the transgenic Bt gene for selecting the resistance to bollworm. The instar-weighted averages were 30.585, 24.182, 16.615, 10.601, 10.123, 7.440 and 7.215 for theC0, P1, M1, M2, MP1, P2 and MP2 populations, respectively. The variance analysisindicated that the instar-weighted average in C0 was greatly significantly higher thanthat in all other populations, i.e., the performance of resistance to bollworm in C0 washighly significantly lower than all other populations. And the resistance in P1 wasgreatly lower than that of M1, M2, MP1, P2 and MP2, and M1 greatly lower than that of M2,MP1, P2 and MP2. There were no significant differences among M2, MP1, P2 and MP2. Withinthe populations of the first cycle selection, MP1 and M1 were greatly significantlyhigher than P1, and MP1 significantly higher than M1. The populations of the second cycleselection were significantly higher than their initial population M1, but no significantdifference among them. The boll size, seed index, the percent of the first harvest yield,fiber length, strength and elongation of the resistant plants to bollworm were significantlylower than that of sensitive plants to bollworm. And the yield of seed and lint cottonof the resistant plant to bollworm were lower than that of the sensitive to bollworm, butno significant difference between them. The boll numbers per plant, lint percent andmicronaire of the resistant plants to bollworm were significantly higher than that of thesensitive plant to bollworm.

Tetracycline selective electrode based on molecularly imprinted polymer particles

Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized. Due to the specific recognition of tetracycline by the particles, the selectivity coefficients for routine interferences were less than 10-4. Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution, the limit of detection of the electrode was reduced to about 2.5 × 10^-8 mol/ L. It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one, with a wide linear working range from 6.0 × 10^-8 to 1.0 × 10^-3 mol/L. The fabricated electrode should be used in pH 2--4, response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0 × 10^-6 mol/L and no more than 30 min at the concentration of 1.0 × 10^-8 mol/L.

Selection rules for electric multipole transition of triatomic molecule in scattering experiments

In the electron or x-ray scattering experiment,the measured spectra at larger momentum transfer are dominated by the electric dipole-forbidden transitions,while the corresponding selection rules for triatomic molecules have not been clearly elucidated.In this work,based on the molecular point group,the selection rules for the electric multipolarities of the electronic transitions of triatomic molecules are derived and summarized into several tables with the variation of molecular geometry in the transition process being considered.Based on the summarized selection rules,the electron energy loss spectra of H2O,CO2,and N2O are identified,and the momentum transfer dependence behaviors of their valence-shell excitations are explained.

SCAR Markers Assisted Selection for a Bentazon Susceptible Lethality Gene (ben) in Rice

In progenies resulting from crosses involving rice cultivar Norin 8m susceptible to bentazon as the donor of ben gene, SCARs tightly linked to ben were utilized for selection of ben. The homozygous and heterozygous genotypes with ben could be identified with the SCARs. The molecular markers offer a powerful tool for indirect selection of ben and can accelerate the introgression of ben into current rice cultivars.

Molecular dynamics simulation of ion selectivity traits of nickel hexacyanoferrate thin films

The ion selectivity of nickel hexacyanoferrate thin film to alkali cations in ESIX (electrochemically switched ion exchange) processes was investigated using molecular dynamics(MD) techniques; water and cation (Na+ and Cs+) intercalation, configuration, and dynamics in reduced nickel hexacyanoferrate structures with different cation combinations were studied and compared with the experimental results. In the simulations, water was represented by an extended simple point-charge(SPC/E) model, and all other atomic interactions were represented by a universal force field(UFF). The potential energies of various cations combination (Cs+ and Na+) in reduced i-NiHCF and 1 mol/L Cs/NaCl mixed solution were obtained. In most cases, the total potential energy of the solid is reduced when water is intercalated into the various reduced NiHCF structures. Combining the solid and the solution simulation results, it is shown that the solid composition of 3Cs+/1Na+ is the stablest structure form (NaCs3Ni4[Fe(CN)6]3) over a range of solution compositions.