Ameliorating Effects And Mechanism Of Uniconazole On Soybean Under Waterlogging Stress

In this study,two soybean varieties,Glycine max L.Kenfeng 14 and Glycine max L.Kenfeng 16,were subjected to watedogging at R1 growth stage,then leaf sprayed uniconazole(S3307)was used as control means withing pot control test.The following data of the two soybean varieties were determined in parallel: biological characteristics,yield components,photosynthetic parameters,material accumulation,key protective enzyme activity,endogenous hormone content,osmotic regulating material content,sugar content,amino acid content in soybean seeds and other physiological and biochemical indexes,meanwhile the soybean root and leaf vegetative organs ultra microstructure were determined,and soybean transcriptome data were also comprehensively analyzed to emphatically study the regulatory effect and the mechanism of S3307 on alleviating waterlogging stress of soybean.The main results were as follows:1.From the perspective of production performance,when the two soybean varieties were subjected to waterlogging stress at R1 stage,the number of per plant pods,hundred-grain weight,dry matter accumulation were reduced,the rate of wilted pods and pyrene grains were increased,the leaves were easy to fall off,the roots weight were reduced,which resulted in a significant reduction of soybean production by 21.95%~39.58%.During waterlogging stress at R1 stage,the yields of Kenfeng 14 and Kenfeng 16 were similar by the CK(treated with normal water supply)and leaf sprayed S3307 treatments,the individual treatment production performance by S3307 treatment was even higher than CK treatment.Leaves sprayed with 50 mg/L S3307 treatment significantly reduced the wilted pods rate(p<0.01),significantly increased the pyrene grains rate(p<0.01),promoted the dry matter accumulation and inhibited the soybean yield decrease.2.From the perspective of growing development,when the two soybean varieties were subjected to waterlogging stress at R1 stage,it mainly reduced the lateral roots number,root injury flow and the effective flowers and fruits number,shortened the functional leaves life,which finally significantly inhibited the soybean growing development.Compared with CK(treated with normal water supply)during waterlogging stress at R1,leaf sprayed SS3307 treatment decreased the height of Kenfeng 14 and Kenfeng 16,increased the number of branches and the effective number of flowers and fruits.Under S3307 treatment,the two soybean varieties with the longest leaf life,longest photosynthetic time and longest retention ability;with strong root system;with high content of stems lignin and neutral detergent fiber.Leaves sprayed with 50 mg/L S3307 treatment significantly improved the soybeans filling ability which was benefit to the soybeans healthy growth and relieve the damaging from waterlogging stress.3.From the perspective of physiological indicators,when the two soybean varieties were subjected to waterlogging stress at R1 stage,it significantly reduced the leaves stomatal conductance,leaf net photosynthetic rate,SPAD value,and photosynthetic electron transfer rate,resulting in a significantly decreased in soybean photosynthetic performance.Leaf sprayed S3307 treatment increased the leaves net photosynthetic rate by 15.36% ~ 48.12%;the photosynthetic electron transfer rate increased fastest with the increasing of light intensity and showed an S-shaped curve.The SPAD value,intercellular CO2 concentration,stomatal conductance,leaf transpiration rate,and net photosynthetic rate of the two soybean varieties changing rules in different treatments were as below: waterlogging stress+S3307group> CK group> waterlogging stress group.Leaf sprayed with 50mg/L S3307 played a physiological role in protecting soybeans from waterlogging damaging.4.From the perspective of biochemical indicators,when the two soybean varieties were subjected to waterlogging stress at R1 stage,it significantly reduced the antioxidant enzymes activity,reduced the abundance level of related protein in soybean leaves,reduced the abundance level of key enzymes in the tricarboxylic acid cycle,reduced the soluble sugar and sugar content,also resulted in hormone imbalance.The content of sucrose,soluble sugar,fructose,and starch in two varieties with S3307 teratment were significantly increased(p<0.05),the activities of antioxidant enzymes SOD and POD were significantly increased(p<0.05),the content of MDA was significantly reduced(p<0.05),the soluble protein and proline content were increased.Leaf sprayed with 50mg/L S3307 significantly improved the abundance of key enzymes in soybean tricarboxylic acid cycle,the MDH,IDH and PDH were as following: waterlogging stress+S3307group> CK group> waterlogging stress group;meanwhile,S3307 promoted the stress response of GA3,IAA and ABA.5.From the perspective of microstructure: when the two soybean varieties were subjected to waterlogging stress,the root cell membrane and various organelles integrity were damaged,the cell wall became thin,the formation layer cells were irregularly arranged,the basal granules were disordered,most of the nuclei were degraded,the number of mitochondrial tears and fragments were increased,and most organelles became residues.The S3307 control treatment had a good protective effect on the integrity of cell membrane and organelles of soybean root,the mitochondria and plastids were relatively regulated.When the two soybean varieties were subjected to waterlogging stress,the mesophyll cells,palisade tissue and cell membrane of leaves were damaged in varying degrees;the chloroplast thylakoid was swelled and damaged,the granule was disordered,most of the nucleus were degraded,some mitochondrial cristae were lost,the inside and outer membrane of the chloroplast were disappeared,the number of mitochondrial tears and fragments were increased,and most organelles became residues.the chloroplast was torn and broken,and the chloroplast and mitochondria were mainly residual.The S3307 control treatment had a good protective effect on the mesophyll cells,palisade tissues,membrane integrity and organelle integrity of soybean leaf.Chloroplasts,mitochondria and starch grains were small and orderly.6.From the perspective of transcriptome analysis,a total of 11974 genes involved in hormones and waterlogging stress were identified from Kenfeng 14,among these genes,5454up-and 6519 down-regulated genes were presented.A total of 9787 involved in hormones and waterlogging stress were identified from Kenfeng 16,among these genes,5102 up-and 4685down-regulated genes were presented.After spraying S3307,more up-regulated genes were enriched in photosynthesis pathway,lipid metabolism pathway,and antioxidant-related metabolic pathway.Besides,more pyruvate kinase was expressed,the accumulation of ethanol in anaerobic metabolism was reduced,the root autotoxicity was reduced;Synthetic genes of phenylpropanoids and flavonoids were up-regulated,ascorbic acid binding capacity was up-regulated,cell organelles modify and function ability were enhanced.Among down-regulated expressed genes,carbon metabolism,nitrogen metabolism and lipid metabolism had been severely affected,which were consistent with the production,physiological,and biochemical data.According to q PCR analysis,the pyruvate kinase genes presented in different treatments of soybean were as following order: waterlogging stress+S3307treatment> CK treatment >waterlogging stress treatment,S3307 had a regulatory effect on reducing the path of pyruvate to ethanol;The DNA damage repair pathway was mainly dominated by nucleotide excision repair pattern;4 closely related to photosynthesis genes were selected in the range of highly differential target expressed genes with FC ? 2 and FDR<0.01,they were 15G221300/Glyma.02G104600[Kenfeng 14],Glyma.02G156800/Glyma.01G198100 [Kenfeng16],respectively.It is speculated that the above four DEGs were responsible for the significant differential expression of improving net photosynthetic rate and stress resistance.In summary,the application of S3307 strengthens the directional regulation,promotes the soybean growth and development,improves the soybean production performance,plays a targeted role in the stable expression of soybean anti-stress effect,effectively hedge against the hazard of waterlogging stress,which finally illuminate the resistance mechanism of soybean under short-term waterlogging stress.The application of S3307 has a broad prospect in anti-stress cultivation.