Genetic Diversity Evaluation Of Male Sterile Lines Population Pollinated With Multiple Parents

Soybean is an important source of oil and protein and has a long history of processing and utilization in China.However,since the end of the 20 th century,the total import of soybean seeds in China has increased year by year.The domestic soybean does not meet consumption needs in China.Heilongjiang Province is rich with the black loamy soil.For many years,Heilongjiang Province has contributed to one third of the yield of soybean in China.However,with the increasing import of soybean in China,the soybean production in Heilongjiang Province has been greatly influenced by the international soybean market outside China.The planting area is decreasing year by year.How to improve the yield and the quality of soybean seed in China has become a major problem for soybean breeders.Unforturnely,most soybean varieties grown all over the world are only derived from a few excellent parents resulting in a high similarity of genetic background and a narrow genetic basis.It is difficult to make a significant inprovement in the yield of new releasing varieties,and it is diffcult to maintain high yield under biotic or abiotic conditions.In order to break this bottleneck situation,creating new germplasm resources is an effective approach.The mixed pollination of multiple parents can significantly increase the genetic diversity of plant germplasms.It is easy to pollinate with the mixture pollen of multiple parents.Parental pollen randomly pollinates the male sterile line,which can easily and efficiently use the sterile line to generate new germplasms.At the same time,the recurrent selection method can isolate excellent individuals with rich genetic background,rich germplasm resources which can effectively overcome the problem of narrow genetic basis.Therefore,102 excellent soybean germplasms planted in Heilongjiang Province were used and planted with sterile line of ms1 and ms6 in one row space to construct two sterile groups of ms1 and ms6.Among them,the ms1 sterile line is divided into three sub-populations according to late maturity,including mid-early maturity and special use.Then,the validated 38 pairs of polymorphic SSR markers covering 20 pairs of chromosomes in soybean was used to check the genetic diversity of the sterile parent and offspring population in 2017 and 2018.The sowing effect in different time,covered effect with black box and honeybee on pollination were also discussed to improve the genetic diversity of progeny population and broaden the genetic basis.The main results are as follows:?1?Among the different generations of different generations,the highest value of the average number of alleles detected by the 38 SSR markers was the F₄ progeny group of ms6,and the average allelic variation was 8.86.The results of genetic variation test on sterile material indicate,the average allelic variation of Sat₂19 locus,Satt210 locus,Satt373 locus,Satt186 locus,Sat₃37 locus,and average Shannon diversity index are rela tively high.The genetic diversity of the soybean sterile line population can be tested successfully.?2?The average allelic variation and the average Shannon diversity index in F₁,F₂,F₃ and F₄ generations increased with the increase of algebra.They were all higher than that of the parent of the sterile line and the mixed parent.The pollination with the mixed parents to the male sterile line increased the genetic diversity of its offspring population s.As algebra increases,so does diversity.?3?The average allelic variation and the Shannon diversity index of the ms6 population were generally higher than the ms1-1 subgroup,the ms1-2 subgroup and the ms1-3 subgroup.Comparing the genetic diversity among the subgroups of each generation of the offsprings of ms1,ms1-2 exhibited the most abundant genetic diversity in each generation.?4?The average protein contents of the F₁,F₂,F₃,and F₄ generations in the offspring of the sterile line were 42.10%,41.84%,41.42%,and 41.32%,respectively.The average oil contents were 19.85%,19.69%,20.21%,20.26%,respectively.The average protein contents of the three subgroups of ms1-1,ms1-2,and ms1-3 were 41.05%,42.11%,and 41.49%,respectively.The average oil contents were 20.50%,20.33%,and 19.89%,respectively.The average protein and oil contents of the ms1 parent were 40.95% and 17.90%,respectively.The results showed that the quality traits of the offspring of the soybean male sterile line was improved by multi-parent mixed pollination,and the protein plus oil content was higher than that of the parent sterile line.?5?The average numbers of seeds in the three subgroups of ms1-1,ms1-2,and ms1-3 were 94.53,55.81,and 81.79,respectively.The average 100-seed weights were 18.34 g,19.03 g,and 16.64 g,respectively.The average numbers of grains and the average 100-seed weights of the ms1 sterile line parent were 30.78 g and 13.14 g,respectively.It was indicated that the multi-parent mixed pollination increased the yield of the offspring population in ms1,and the improvement of its quality trait had no negative effect on the yield.?6?Most of the offspring of the sterile lines in the same year can mature normally and each period is slightly delayed compared with the local control varieties;Th e agronomic traits of the development stages had been improved which enriched the diversity of the growth period.?7?The multi-parent mixed pollination in natural condition and addition with honeybee could both expand the genetic diversity of the offspring of the sterile lines.However,the genetic diversity of the offspring obtained after pollination by bees was greater than that of the sterile lines obtained in the natural condition.