Effects of Drought Stress on Key Enzymes of Carbon Metabolism, Photosynthetic Characteristics and Agronomic Traits of Soybean at the Flowering Stage under Different Soil Substrates

Soybean is an important legume food crop,and its seeds are rich in nutrients,providing humans and animals with edible oil and protein feed.However,soybean is sensitive to water requirements,and drought is an important factor limiting soybean yield and quality.This study used Heinong 84(drought resistant variety)and Hefeng 46(intermediate variety)as tested varieties planted in chernozem,albic,and black soils.The effects of drought stress on the activities of key enzymes in carbon metabolism and photosynthetic characteristics of soybean were studied during the flowering stage,most sensitive to water.(1)The activities of SS-1,6PGDH,and G6PDH enzymes in soybean leaves first increased and then decreased under drought stress.The enzyme activity was the highest under moderate drought stress and weakest in the blank group.(2)Drought stress increased Phi2,PhiNO,and Fm in soybean leaves and reached the highest value under severe drought;with the increase in drought stress,PhiNPQ and Fv/Fm of soybean leaves gradually decreased,reaching the lowest under severe drought.(3)With the increase in drought stress,F0 and Fs of soybean leaves showed a single peak curve,and the maximum was at moderate drought.(4)Correlation analysis showed that F0 was greatly affected by varieties and soil types;Fs,F0,and Fm soil varieties had a great influence,and chlorophyll fluorescence parameters were affected differently under drought stress with different drought degrees.(5)Drought stress changed the agronomic traits and yield of soybean.With the increase of drought degree,plant height,node number of main stem,effective pod number,100-seed weight and total yield decreased continuously.(6)Drought stress affected the dry matter accumulation of soybean.With the increase of drought degree,the dry matter accumulation gradually decreased.Among them,the leaf was most seriously affected by drought,and SD decreased by about 55%compared with CK.Under the condition of black soil,the dry matter accumulation of soybean was least affected by drought.

Proteomics Analysis of Soybean Seedlings under Short-Term Water Deficit

Soybeans are one of the most important grain crops worldwide.Water deficit,which seriously affects the yield and quality of soybeans,is the main abiotic stress factor in soybean production.As a follow-up study,the droughttolerant soybean variant Heinong 44 was analyzed via proteome analysis.Soybean was exposed to water deficit for 0,8,and 24 h,and protein samples were extracted for detection of differentially expressed proteins.Protein sequencing of leaf tissues under water stress yielded a total of 549 differentially expressed proteins:75 and 320 upregulated proteins as well as 70 and 84 downregulated proteins were obtained after 8 and 24 h of water deficit,respectively.Gene Ontology analysis revealed that most of the differentially expressed proteins(DEPs)were involved in catalytic activity,molecular function,and metabolic processes,whereas some of them were involved in photosynthesis,carbon metabolism,and energy metabolism.We also identified some differentially expressed proteins that may be involved in the regulation of water deficit response.Our study provides a theoretical basis for the breeding of drought-resistant soybean varieties.

Transcriptome Analysis of Soybean in Response to Different Sulfur Concentrations

Sulfur is an indispensable nutrient for plant growth and development,and is important in the synthesis of sulfurcontaining amino acids.Although several studies on the effects of some macronutrients,including nitrogen and phosphorus,have been conducted on the performance of several crops at the genomic level,studies on the effect of sulfur on crop performance are limited.Therefore,this study aimed to examine the effect of different sulfur concentration on the transcriptome of soybean.Additionally,soybean yield parameters were also examined.Two soybean varieties,DND252 and HN84,were exposed to low and high concentrations of sulfur,and differentially expressed genes(DEGs)were identified using transcriptome analysis.The study results showed that the DEGs identified in the DND252 variety were involved in stimuli response,DNA binding and cell periphery under low sulfur concentrations.Also,the DEGs identified under high sulfur concentration were involved in membrane and membrane parts.Additionally,DEGs identified in the HN84 variety under low sulfur concentrations had similar functions as those identified in DND252 under high sulfur concentrations,indicating that HN84 was more sensitive to sulfur concentration changes than DND252.However,under higher sulfur concentrations,the DEGs identified in HN84 were primarily involved in membrane and membrane parts,indicating that high sulfur can cause cell membrane damage.Furthermore,soybean grown using 2.0 mmol/L sulfur had the best yield.The findings of this study identified candidate genes for the breeding and development of sulfur-efficient soybean varieties.