QTL Mapping And Candidate Gene Mining Of Soybean Nodules Related Traits

Soybean is an important crop in China.Soybean is an important part of building the dietary structure of Chinese because of it contain high protein and high fat content.So,the annual consumption is huge.However,the total output and unit area of soybeans in China are all far from the large soybean producing countries.In the case of high consumption and insufficient production,in order to maintain the supply of soybeans,we have to rely on continuous import methods.As the current increase in soybean production has risen to the national strategic level,more and more breeders will focus on improving soybean production.Soybean yield is controlled by multiple traits,plant height,internode number,number of pods,and so on.Nitrogen fixation efficiency is one of the important factors controlling soybean yield.Improving nitrogen fixation efficiency can greatly increase soybean yield.At present,the nitrogen fixation mechanism has been initially analyzed,but there are still many areas to be clarified.The discovery of genes related to nitrogen fixation is of great significance for improving soybean yield and probing nitrogen fixation mechanisms.At present,the identification of genes and the identification of functions are mostly based on reverse biogenetics.It is used to identify the effects on traits start by genomic level.Although this method has many advantages,but its uncertainty about the target trait.Forward genetics,from the beginning of phenotypic research,locates genes associated with it.Although the experimental period is long,but the target genes are accurately located.This experiment is to use the method of forward genetics to locate and analyze the genes controlling the number of soybean nodules.The main findings are as follows:(1)A RIL population was constructed by hybridization of an Glycinesoja and a cultivar with different nitrogen fixation efficiency.A genetic map with a total map distance of 3403.94 cM was constructed based on the RIL population,and six genes were detected by QTL mapping with nodulation.(2)Functional annotation and expression analysis of genes in the QTL interval by using bio informatics methods.All of six genes are encoded proteins,mainly includes:high light-inducing proteins,protein kinases,small peptides,C2H2 transcription factors,and one gene function is unknown.Named GmHLIP,GmPK1,GmSP,GmPK2,GmRSD,and Gm07G57.GmHLIP is highly expressed in leaves,also be expressed in flowers,pods and seed coats.GmPK1 is highly expressed in leaves,pods and mesolates,and the expression in underground parts is very low.GmPK2 is highly expressed in flowers and roots,Gm07G57 is specifically expressed in flowers,and GmRSD is specifically expressed in nodules.(3)Real-time quantitative PCR was performed on different soybean tissues treated with different nitrogen concentrations in different nitrogen concentrations,and a specific gene was found in soybean nodules treated with neither low or no nitrogen nutrient solution.It is listed as a key research gene for subsequent transformation of soybean hairy roots to verify its function.(4)The overexpression vector(OV)was used to transform the soybean hairy root to observe the phenotype.After three independent biological replicate experiments,the number of nodules in the treated group was significantly different from the control group.Proved that overexpression can effectively regulate the number of soybean nodules.