The Molecular Fundamental Research On Main Agronomic Traits Of Soybean

Soybean is the world’s most important protein and oil crops, rich in protein, fat andisoflavones and other nutrients, has become one of the most important sources ofhuman food, animal husbandry feed protein and fat. Soybean has always occupied animportant position in our country’s agricultural production. But in recent years, as thecomparative efficiency of planting is lower than other crops, soybean yield in Chinahas been hovering not before, and this situation has been a serious threat to thenational food security. Study on the molecular basis of main agronomic characters ofsoybean, will provide an important guiding significance for improving China’ssoybean production.Five representative soybean cultivars for main agronomic traits are selected tostudy in this thesis, which are Williams82, Jilin35, Hedou12, Zhonghuang42, and075140. We observed development process of the main agronomic traits, analyzed therelationship among these key agronomic traits, constructed the virtual growth ofsoybean growth model by using L-system, and cloned and analyzed some importantgenes of soybean yield and quality, the results of this study will provide theoreticalguide for cultivating high quality and yield of soybean. The main results are asfollows:1. Analysis the rules of main agronomic traits development and construction ofgrowth model1.1Analysis the rules of main agronomic traits development(1) Sixteen agronomic traits of five soybean varieties were measured in bothvegetative growth stage and reproductive growth stage. The results showed that thegrowth habit is closely related to some main agronomic traits during vegetativegrowth stage, such as, plant height, node number, and branch number. These traitswere decreased from indeterminate to determinate. But the relationship did not appearduring the reproductive growth stage, indicating the formation of these yield traitsvarietal differences occurred mainly in the vegetative stage.(2) Correlation analysis of agronomic traits showed that, yield per plant and planttype traits were positively correlated, negatively correlated with fertility later days;protein content and100-grain weight had a positive correlation, and the node number,plant height, grain number per plant, seed weight per plant was negatively correlated;fat content and total grain number, total pod the number has significant positivecorrelation, but negatively related to growth stage, flowering, pod, weight of100grains and height of bottom pod.(3) Genetic variation coefficient of five varieties were analyzed, the geneticvariation coefficient of16agronomic characters in the whole growth period wasminimum, while the coefficient of variation of the bottom pod high maximum. Thesesuggest that there are high possibility of improvement soybean breeding by thebottom pod height, and low possibility of the whole growth period.(4) The factor analysis results show that sixteen agronomic traits can be divided intofive main factors, which are the plant type factor (plant height, node number, branchnumber), developmental stages factor (early growth factor, growth stage, flowering,pod, pod beginning), pod-grain factor (total number of pods per plant, total grain number and grain weight per plant), growth factor (stem width and100-seed weight)and quality factor (protein content and fat content). The relations of agronomic traitsof soybean are complex, factor analysis have simplified these traits as five main factors,which will be beneficial to explore the key genes controlling agronomic traits.1.2Construction of the growth model of soybean by using L systemBased on measured data of plant height, nodes on main stem and branch number,the virtual plant growth model of Williams82was constructed using the L-system byanalysis of growth parameters on28,42,56,70and84days. This work provides abasis for the molecular design breeding in soybean. According to the preliminaryanalysis and calculation model, developmental process of soybean showed anon-uniform growth model.2. Study on soybean yield traits and quality traits related genes2.1Cloning and function study of UFO gene homologous genes of soybeanThe UFO homologous genes of soybean, GmUFO05g and GmUFO08g, werecloned using Williams82inflorescence material. The over-expression and silenceplasmids of GmUFO05g and GmUFO08g gene were constructed, and these plasmidswere transferred into Arabidopsis thaliana using Agrobacterium-mediatedtransformation. Some resistant seedlings have been selected, and the phenotypeanalysis is underway.2.2Analysis of DGAT genes from soybeanDGAT is the key gene of plant fatty acid synthesis and metabolism. Ten soybeanDGAT genes were identified by bioinformatics analysis, which distributed on6chromosomes, and belonged to DGAT1, DGAT2, DGAT3subfamily. The expressionpatterns of these three subfamilies are not identical; the expression of DGAT2subfamily is the most extensive, DGAT3subfamily expression position is the least.The difference between DGAT family of soybean gene in structure and expressionpatterns indicated their functional diversity and complexity, which provides importantinformation for improving the quality of soybeans.The innovation of this thesis:1. Study the developmental process of agronomic traits of five representativevarieties of soybean; we got the distribution rules of flower number of eachnode, pod number, protein and fat content.2. For the first time GmUFO05g and GmUFO08g were cloned in soybean, studiedfunctions these genes.3. Investigate the sequence and expression characteristics of soybean DGAT bybioinformatics analysis, which provides useful information for improving thequality of soybeans.