The Improvement of Soybean Salt Tolerance by Overexpressed GmPAO1

Polyamines play an important regulatory role during plant growth and development and adversity stress,and polyamine oxidase(PAO)is involved in polyamine catabolism.In this study,an up-regulated polyamine oxidase gene GmPAO1 was obtained by transcriptome sequencing analysis and screening at soybean seedling stages.Also,its expression pattern and function were analyzed.The identification results of transgenic GmPAO1 soybean positive lines showed that the relative expression level of GmPAO1 in the overexpressed lines was increased under salt stress.With increasing stress concentration,the seed germination rate decreased.However,the seed germination rate of the overexpressed lines was significantly higher than that of the control lines,and the phenotypic character of the root systems was also better than that of the control lines.The measurement of superoxide dismutase(SOD)and peroxidase(POD)activities and malondialdehyde and hydrogen peroxide contents revealed that the overexpressed soybean lines significantly increased the SOD and POD activities,significantly reducing the malondialdehyde content.Although the hydrogen peroxide content in the transformed plants gradually increased,the hydrogen peroxide content in the overexpression lines was still lower than that in the gene editing lines.Based on this,it was preliminarily judged that GmPAO1 can improve soybean salt tolerance.

Identification of Resistance to Pathogenesis Related Protein GmPR1L in Tobacco Botrytis cinerea Infection

Soybean(Glycine max(Linn.)Merr.)annual leguminous crop is cultivated all over the world.The occurrence of diseases has a great impact on the yield and quality of soybean.In this study,based on the RNA-seq of soybean variety M18,a complete CDS(Coding sequence)GmPR1L of the pathogenesis-related protein 1 family was obtained,which has the ability to resist fungal diseases.The overexpression vector and interference expression vector were transferred into tobacco NC89,and the resistance of transgenic tobacco(Nicotiana tabacum L.)to Botrytis cinerea infection was identified.The results show that:Compared with the control,the activities of related defense enzymes SOD(Superoxide dismutase),POD(Peroxidase),PAL(L-phenylalanine ammonia-lyase)and PPO(Polyphenol oxidase)in the over-expressed transgenic tobacco OEA1 and OEA2 increased to different degrees,and increased significantly at different infection time points.The activities of defense enzymes in the interfering strains IEA1 and IEA2 were significantly lower than those in the control strains.The results of resistance level identification showed that the disease spot rate of OEA1 was significantly lower than that of the control line,and the disease spot rate of OEA2 was significantly lower than that of the control line.The plaque rate of the interfering expression line IEA1-IEA2 was significantly higher than that of the control line.It is preliminarily believed that the process related protein GmPR1L can improve the resistance of tobacco to B.cinerea.

Microstructure and strengthening mechanism of hot-extruded ultralight Mg-Li-Al-Sn alloys with high strength

Duplex-structured Mg-7Li-2Al-1.5Sn alloys with high strength were fabricated and their strengthening mechanism was investigated.The Mg-7Li-2Al-1.5Sn alloys were prepared by casting and extruded at the temperature of 533 K with an extrusion ratio of 25:1.The microstructure and mechanical properties of Mg-7Li-2Al-1.5Sn alloys were systematically investigated by OM,XRD,SEM,TEM,and tensile tests.The results show that Mg-7Li-2Al-1.5Sn alloys are mainly composed ofα-Mg,β-Li,LiMgAl_(2),Mg_(2)Sn and Li_(2)MgSn phases.The yield strength(YS),ultimate tensile strength(UTS)and elongation(EL)of the extruded alloy at room temperature reach 250 MPa,324 MPa and 11.9%,respectively.A lot of Sn-rich precipitates(Mg_(2)Sn and Li_(2)MgSn)are precipitated during extrusion with an average size of∼14 nm,which is beneficial to the grain refinement.Dynamic recrystallization occurs during hot deformation and the nanoprecipitates effectively refine the dynamic recrystallized(DRXed)grains.Besides,the residual dislocations existed in DRXed and un-DRXed grains result in the dislocation strengthening in the extruded alloy.Mg7Li-2Al-1.5Sn alloys possess excellent high-temperature mechanical properties with the YS,UTS and EL of 200 MPa,237 MPa and 26.7%at 423 K,respectively.Sn-rich precipitates with good thermal stability can effectively prevent grain growth,which is good for the improvement of the high-temperature performance of Mg-Li-Al-Sn alloy.