Functional Study On Soybean GmGAI Gene Regulating Flowering Time Via Gibberellin Pathway

Soybeans are important grain and oil cash crops and are widely cultivated worldwide.Growth period genes not only regulate flowering time and maturity,but also affect soybean yield by regulating plant height,growth habit,and number of branches.Soybean growth period trait improvement has always been a hot issue of research.Flowering time is not only affected by external environmental factors?such as light and temperature?,but also regul ated by the endogenous signals of the plant itself.Gibberellin?Gibberellin?,as a plant growth regulator with high efficacy and wide utility,plays an important role in the whole development process of plants including germination,elongation,flowering and fruiting.DELLA protein is a negative feedback protein in the gibberellin process,which restrains the growth and development of plants and inhibits plant flowering.By studying the function of soybean GmGAI gene encoding DELLA protein in plants,the regulatory role of this gene in regulating soybean growth period was clarified,and the molecular mechanism of GmGAI gene involved in gibberellin regulation and regulation of soybean was revealed,which provided a theoretical basis and Experimental data.In this study,the effect of gibberellin and photoperiod on the expression pattern of GmGAI gene was analyzed by real-time fluorescent quantitative PCR;the overexpression vector p B7WG2-GmGAI was transformed into Arabidopsis thaliana,and the homozygous T ₃generation plants were treated under long-day conditions As well as phenotype identification under gibberellin treatment;through RNA-seq,downstream differentially expressed genes were obtained,and GO analysis and KEGG Pathway analysis were used to clarify the molecular mechanism of GmGAI gene involved in the regulation of gibberellin pathway flowering.The GmGAI-GFP expression vector was constructed,and transient expression in tobacco determined the expression position of GmGAI gene in cells.The main findings are as follows:?1?The expression of soybean GmGAI gene is induced by short-day sunshine conditions and reaches its peak at 12 h after illumination;gibberellin inhibits the expression of GmGAI gene.?2?Construct the p B7WG2-GmGAI overexpression vector with a fragment length of 1572bp.Transform Arabidopsis thaliana using the inflorescence infection method mediated by Agrobacterium.After PCR and western blot,three homozygous transgenic lines were obtained;under long-day conditions,GmGAI overexpression plants showed obvious late blooms,the plants were extremely dwarfed,the number of rosette leaves decreased,and the number of pods decreased;under gibberellin treatment,through the analysis of plant root length,hypocotyl length,plant height and pod number It was found that GmGAI overexpressing plants were less sensitive to gibberellin than wild-type plants.This difference gradually decreased with the increase of gibberellin concentration,indicatin g that GmGAI overexpressing plants reduced the promotion of gibberellin on plant growth It is a negative regulator in the gibberellin pathway.?3?The total number of expressed genes detected by RNA-seq was 24004,and there were3669 genes that were significantly differentially expressed,of which 1341 were up-regulated and 2328 were down-regulated;GO enrichment analysis found that differentially expressed genes were mainly enriched in biological processes,Including stimulatory response,biological regulation process,response to chemical substances,gene expression regulation;a KEGG Pathway enrichment can be seen that differentially expressed genes are significantly enriched in plant hormone signal transduction pathways.In the gibberellin signaling pathw ay,GmGAI upregulates the expression of the positive acting factors At GID1A,At SPL5,and At SCL29 in the gibberellin pathway,and down-regulates the expression of the negative feedback factors At MYR1 and At RGL2 in the gibberellin pathway.This indicates tha t GmGAI is a negative feedback factor in the gibberellin pathway.?4?Subcellular localization of the GmGAI gene and construction of GmGAI-GFP expression vector for transient expression in tobacco.The results prove that the GmGAI gene is localized on the nucleus.