Molecular Mechanism Of Soybean GmHXK1 Regulating Root Nodule Development And Its Application

Soybean is an important oil and food crop in my country,and my country is the origin center of soybean.At present,my country’s soybean yield is low and import dependence is strong.How to improve my country’s soybean yield is a key issue that needs to be solved urgently.The symbiotic nitrogen fixation system of rhizobia and legumes is the biological nitrogen fixation system with the highest nitrogen fixation efficiency and the largest nitrogen fixation in nature.The biological nitrogen fixation function of rhizobia can provide sufficient and stable nitrogen sources for soybean growth and development,reduce fertilization,and improve soybean yield and quality,which is of great significance to ensuring national food security.Glucose is an energy center molecule,which plays an important role in various plant growth and development processes,and is closely related to the plant nitrate transport system.It has been reported that glucose can regulate soybean nodule development,but the molecular mechanism is still unclear.Hexokinase（HXK）is a glucose phosphorylase that converts glucose into glucose-6 phosphate,which is the first step in the glucose metabolism pathway and plays an important role in the glucose metabolism pathway.In this study,the molecular mechanism of regulating soybean nodule development was studied by bioinformatics methods and molecular biology,and new soybean germplasms with high nitrogen fixation were screened.The main findings are as follows:（1）In this study,using bioinformatics and molecular biology methods,the soybean HXK1 family genes were identified and cloned,which were named GmHXK1 a,GmHXK1 b,GmHXK1 c respectively.Through the analysis of their tissue expression patterns and subcellular localization,it was found that the three soybean HXK1 family genes in soybean It is expressed in tissues and organs,and is mainly localized in the nucleus and cell membrane.（2）After soybean overexpression GmHXK1 a,GmHXK1 b,GmHXK1 c three genes hairy roots were inoculated with Rhizobium,the gene expression was significantly up-regulated,and the expression reached the highest level at 7 days;It has hexokinase activity and is induced by Rhizobium,among which GmHXK1 c has the strongest kinase activity after being overexpressed by Rhizobium trichomes.（3）Genotyping of GmHXK1 s using the soybean hairy root system.The results showed that overexpression of GmHXK1 a and GmHXK1 c significantly increased the number of soybean nodules,while overexpression of GmHXK1 b did not change the number of soybean nodules.The number of root nodules increased significantly,and the results indicated that GmHXK1 a and GmHXK1 c genes may affect soybean sugar signal and soybean nodulation signal at the same time.（4）Molecular markers were used to screen soybean germplasm resources with significant differences in the number of nodules.It was found that the higher the expression of GmHXK1 a gene,the more the number of nodules.It was preliminarily predicted that its gene expression would affect the number of nodules in soybean,which may be a molecule with excellent nitrogen fixation in soybean mark.Based on the above results,GmHXK1 a and GmHXK1 c may affect the number of soybean nodules through glucose signals.GmHXK1 gene plays an important role in the nitrogen fixation process of soybean nodules,which provides important genetic resources for the breeding of soybean high nitrogen-fixing varieties.