| At present,biological fertilizers have been widely used in agricultural production.Legumes often fix nitrogen through the nodules of rhizobium to enhance their absorption of nitrogen.In addition,calcium diphenylurea sulfonate can also effectively promote the nodulation and nitrogen fixation of soybeans.It is an environmentally friendly exogenous compound synthesized by the biomimetic method using coconut milk extract as a raw material.In this experiment,’Fendou 78’ was used as the material,and the two kinds of exogenous S.fredii and calcium diphenylureasulfonate(DSC)on the rhizosphere effect of soybean were taken as research objects.Soybean agronomic traits,soybean rhizosphere soil bacterial structure and function,and soybean root interaction transcriptome were studied to provide theoretical support for the application of the two in soybean cultivation.(1)The test uses potted plants in a greenhouse,and a total of 8 groups are set up: blank control(CK),S.fredii(N1),3 g/L DSC(N2),6 g/L DSC(N3),12 g/L DSC(N4),S.fredii+3 g/L DSC(N5),S.fredii+6 g/L DSC(N6),and S.fredii+12 g/L DSC(N7).At the flowering and pod-setting stages,the physical and chemical properties of the rhizosphere soil and the agronomic traits of soybean were measured and counted,respectively.The results showed that S.fredii and DSC could significantly increase the total nitrogen and total phosphorus content of rhizosphere soil,but had little effect on the total potassium content.Among them,the highest nitrogen and phosphorus content was N6,followed by N1 and N3.N3 and N6 soybean plants had the best apparent traits.Compared with CK,the number of pods increased by27.78%~64.71%,55.56%~117.65%,and the number of soybean seeds increased by 31.82%~91.18%,47.73%~150.00%.Compared with CK,the nodule fresh weight of N6 increased by 16.48%~48.05%,11.11%~40.82%and 29.09%~76.92% respectively.(2)The results of the above experiments indicate that DSC with a content of 6 g/L is the optimal concentration for the treatment.Therefore,CK,N1,N3,and N6 were selected for high-throughput sequencing of rhizosphere soil bacterial communities.The results showed that the diversity of the rhizosphere bacterial community of N1 and N3 was lower than that of CK.According to statistics,S.fredii,DSC,and S.fredii+DSC treatment will enrich some bacterial flora that have nitrogen metabolism,antagonize pathogenic bacteria,and promote the absorption of phosphorus,potassium and other elements,such as Acidovorax,Azoarcus,Azobocter,Cellvibrio,Flavobacterium,Geobacter,Hydrogenophaga,Pseudomonas,etc.(3)Soybean seeds treated with CK,N1,N3,and N6 were selected and cultured in an artificial climate chamber.After 45 days,soybean root samples were taken,RNA was extracted and sequenced based on the Illumina platform: compared with CK,the up-regulated genes in the three groups were far greater than the down-regulated genes.Among them,N1 processing was increased by 4,374,down by 1,649;N3 processing was increased by 3,243,down by 692;N6 processing was increased by 4.289,down by 1,260.Based on GO and KEGG database platforms,significant differential gene alignment results of CK vs N1、CK vs N3 and CK vs N6 were analyzed.The results showed that: S.fredii 、 DSC and S.fredii+DSC treatment promoted hydrolase,glucosyltransferase,phosphatase activity,cell membrane and cell wall synthesis.S.fredii treatment promoted catalytic activity,redox enzyme activity,microtubule formation and other pathways.DSC treatment promotes the synthesis and decomposition of hydrogen oxidase,antioxidant reaction,secondary cell wall structure,phloem development,cellulose,metabolism,secondary metabolism,transmembrane transport and other pathways.Moreover,DSC treatment upregulates genes related to the response cytokinin synthesis pathway,and S.fredii,DSC and S.fredii+DSC treatment upregulates genes related to the biosynthesis pathway in response to gibberellin and salicylic acid.In summary,the application of S.fredii and a reasonable concentrationof DSC in soybean planting can improve the rhizosphere soil environment,promote the accumulation of nitrogen and phosphorus elements in the rhizosphere soil,and effectively enrich some functional flora.Both are based on the regulation of the molecular mechanism of the root system and are also reflected to some extent in the corresponding soybean agronomic traits.Therefore,the results of this research can better provide theoretical basis for the application of two exogenous species S.fredii and DSC in soybean cultivation. |
