Genetic Characteristics Of The Conditional Introgression Line Population Njcilp In Soybean And Its Seed Trait Association Analysis

Soybean [Glycine max （L.） Merr.] originated in China, which is the most important source of plant protein, edible vegetable oil and various functional healthcare in modern society. Soybean plays a significant role in plant oil supply and the development of civil economics. A conditioned introgression lines population, whose name was NJCILP, was constructed from8backcross populations, NN1138-2xKefeng NO.1, NN88-31xN24852, NN88-31xPB26582, NN1138-2×N24852, NN1138-2xN23228, NN1138-2xpeking, NN88-31xpeking and NN86-4xPI342618B, of which50materials （25extreme oil content materials and25extreme protein content materials） were selected from each of the populations based on the average oil content （18.81%） and protein content （46.67%）. A conditioned introgression lines population was composed of subpopulations which was selected from different backcross populations according to certain criteria. Field experimental data from two environments with3repetition and50SSR markers were used to analyze genetic characteristics of NJCILP. Also, association analysis of3seed traits （selected oil content, protein content and unselected100-seed weight） was conducted by using50SSR markers. Donor parents’ratio was estimated in each subpopulation based on the seed traits detected loci. Detected loci of the three traits in joint environment were selected and their relative elite alleles were excavated including the origin and distribution. After that, plant gene pyramiding breeding was verified. The influence of donor parents to seed traits was analyzed through the comparition between seed traits of recipient parents and seed traits of8subpopulations under3environments. Finally, parts of elite lines was selected. Further studies on other elite traits could be conducted after a preliminary understanding on seed traits. Ultimately, high protein content, pest-resistent breeding materials could be obtained. The main results were as follows:1Genetic characteristics of the conditional introgression line population NJCILP in soybean.Genetic characteristics of three phenotype traits. In average environment, the range of oil content and protein content which was selected under certain criteria was15.17-21.46%and36.47-50.77%. The average of oil content is lower than that of recipient parent which was caused by donor parent. However. The protein content is higher than recipient parent. The range of100-seed weight was6.77-19.74g. There existsed significant differences among lines as well as lines xenvironment according to the ANOVA results.The range of theoretical percentage of recipient parents in8subpopulations of NJCILP was92.75-94.25%, while the practical one was86.37-92.72%; The range of donor parents was5.75-7.25%compared with the practical one,7.28-13.63%.After selection, the alleles of parents all show up in their progeny, the loci and alleles were not affected. Meanwhile, allele frequence and dispersion was affected. Compared with PIC of the population and subpopulations, the theoretical value was smaller.Cluster was made using UPGMA method based on Nei’s genetic distance by Powermarker v3.25software which divided the population into three subgroups. NJCILP was also divided into three subgroups by using STRUTURE2.2software. Chi-square test showed the result of three grouping methods-grouping based on recurrent parent, genetic distance and mathematical model-was basically the same, which was more reliable.2Seed traits association ananlysis of conditional introgression line population NJCILP in soybeanThe association analysis of three seed traits was conducted usingthe a two phase correlation analysis method developed by He Jianbo. Under the significance level below0.01,24markers associated with oil content were detected in joint environment, while19markers linked to protein content and32markers linked to100-seed weight were detected. Loci Satt147, Satt005, Satt316, Satt640, Satt681, Satt260and Satt592were novel loci linked with oil content, while Satt640, att681, Satt210, Satt260, Satt114and Sat₄05were novel loci linked with protein content, Sattl47, Satt683, Satt281, Sat₃66, etc.14loci linked to100-seed weight traits. The range of donor parents’percentage was9-15%,8-14%and8-15%based on the detected stable seed traits loci.3Distribution of excavated seed traits alleles and genetic composition of elite lines103alleles for24loci of oil content,83alleles for19loci of protein content and137alleles for32loci of100-seed weight were identified respectively. The distribution of all alleles in400lines and in experimental lines was analyzed and the result was that the more the number of positive alleles, the higher the phenotype would be. However, both high and low phenotypic materials had positive and negative alleles. Plant gene pyramiding breeding was also verified from the analysis of dipersion of alleles, that is, the phenotype would be better after tha accumulation of positive alleles in one line.Donor parents have the tendency of increasing protein content, decreasing oil content and100-seed weitht. The decreasing trend of unselected100-seed weight was bigger than the variation of selected oil and protein content. Compared with the phenotype of the parents, parts of elite lines were selected.15lines of high oil content,15lines of high protein content and15lines of big100-seed weight were selected and the range of variation was20.10-21.67%、48.29-50.77%and18.42-19.74g respectively. The materials had more positive alleles. After that, another15lines were selected whose sum of the three traits was better than others. These lines also had more positive alleles.