QTL-Allele Constitutions Of Yield Hetrosis And Key Factors Of Outcrossing-productivity Of CMS Lines In Soybean[Glycine Max(L.)Merr.]

Heterosis is one of the most effective measures to increase crop yields and improve quality,and has been widely used in Gramineae,Solanaceae,cruciferous and other crops.At present,China has made some progress in the utilization of soybean heterosis.Using the"three lines",a number of hybrid soybean which passed the variety validation has bred.However,the low efficiency of soybean seed production caused it failed to promote the application.Huang-Huai Valley of China is the main planting area of soybean,which need to further screening and determine the high heterosis combination and analyze the genetic basis of soybean yield heterosis.The indusexperimentization of hybrid seeds of high heterosis combination in soybeans ultimately need transfer into the soybean male sterile line to achieve hybrid seed production.Therefore,we need to discuss the influencing factors of male sterile line hybrid seed production.One part in this study:during 2009-2013,two parent group was selected in southwest of Shandong and southeast of Henan,respectively.A total of 150 hybrid combinations has set according to NCII design.Firstly,the heterosis of the combination was analyzed,and the high heterosis combination was selected.Secondly,the genetic basis of soybean heterosis was analyzed.Finally,the combination is improved using the genetic information of the hybrid combinations.The other part in this study:during 2011-2014,in Nanjing and Taiyuan,five soybean cytoplasm-nuclear male-sterile(CMS)lines with their corresponding maintainer lines,and three restorer lines were selected to study the key factors on soybean sterile lines reproduction and hybrid seeds production under open environment.The specific results are as follows:1.Heterosis performance of yield and quality traits on soybean in southwest of Shandong and southeast of HenanIn this study,heterosis of yield on soybean in southwest of Shandong and southeast of Henan was relatively larger,but no obvious heterosis for protein and fat.Average mid-parents heterosis(MPH)was 30.03%for four groups of parents,and 106 combinations significantly with higher mid-parents heterosis,accounting for 71%;average high-parents heterosis(HPH)was 27.71%for four groups of NCII experiments,and 77 combinations significantly with higher mid-parents heterosis,accounting for 51%.Among the combinations,Zhonghuang-13×Jindou-23,Yudou-22 × Gaofeng-1,Yudou-22×Jindou-23,Shanning-16 × Hedou-18,Shanning-14 × Jidou-17,Hedou-19×Jidou-17,Hedou-19×Xu-0801,Hedou-19×Williams82,Zhoudou-13×MN413,Yudou-22×Zhoudou-16,Jidou-17×Zhoudou-19 and Xu-0705×Willimas82 had higher heterosis and yield.Average mid-parents heterosis of these combinations was 49.89%,ranging from 34.00%to 85.41%;average high-parents heterosis of these combinations was 46.57%,ranging from 32.37%to 75.54%.2.Genetic analysis in QTL of yield of hybrid combinations in soybeanSNPLDB(SNP Linkage disequilibrium block)was obtained by RAD-seq(sequencing based on restriction site-related DNA),and QTL-Allele of four groups of NCII experiments was analyzed by PLSRCGA(Partial least square regression combined with genetic algorithm)method.A total of 57 QTLs associated with F1 hybrids were detected in four groups of NCII experiments.These QTLs were distributed on 15 linkage groups.Among them,the QTLs on N(7)and D2(7)linkage groups were the most,then F(6),J(5),C1(5),B2(4),C2(3),M(3),E(3),Dla(3),Dlb(3)and so on.A total of 13 QTLs were significantly correlated with F1 hybrids in the first group of NCII experiment,with a total contribution rate of 74.08%;a total of 22 QTLs were detected in the second group of NCII experiment,with a total contribution rate of 80.31%;a total of 25 QTLs were detected in the third group of NCII experiment,with a total contribution rate of 76.14%;a total of 15 QTLs were detected in the third group of NCII experiment,with a total contribution rate of 79.13%.There were only one QTL that were significantly correlated with F1 hybrids in the four groups of NCII experiments was detected at the same time;three QTLs in the three groups of NCII experiments were detected at the same time;nine QTLs in the two groups of NCII experiments were detected at the same time.3.Analysis of QTL-allele in soybean F1 hybridsThe values of the additive and dominance alleles of each QTL were estimated in four groups of NCII experiments.The value of the additive allele qHy-14-03-A2,qHy-01-03-A1,qHy-06-01-A5 and qHy-16-05-A7 was the highest in four groups of NCII experiments.The parents,Zhonghuang-13、Jinda-53、Jindou-23、Hedou-19、Jidou-17、Shanning-16、Zhoudou-13 and Fu-97211-76 carry more positive additive loci.The value of the dominance allele qHy-13-06-A1/A2,qHy-17-05-A1/A2,qHy-09-03-A1/A2 and qHy-07-01-A2/A3 was the highest in 3 NCII designs.The value of the dominance allele was not related to the value of the additive allele.4.Analysis of genetic basis of hybrid combinations in soybeanThe PLSRCGA method was used to analyze the QTL-allele of four groups of NCII experiments in southwest of Shandong and southeast of Henan.The dominance of different QTL-allele was estimated.It is suggested that the effect sites of soybean hybrids may include additive effect of allele,partial dominance effect of allele,dominance effect of allele and overdominance effect of allele.The results showed that heterozygous loci of combinations was more than homozygous loci in the hybrid combinations.Analysis of genetic composition of F1 hybrid combinations in soybean,the dominant effect of heterozygous loci is the main component of soybean hybrids,and the additive effect is also a part of it.Overdominance allele is the genetic basis of the heterosis of soybean yield.5.Analysis on combing ability of yield among key parental material in soybeanThere were significant difference between the general combining ability(GCA)and special combining ability(SCA)of the four groups of NCII experiments based on yield phenotype,and there was significant interaction with the year.We found a group of potential valuble parents through calculating the general combining ability(GCA)of the four groups of NCII experiments:Yudou-22,Zhonghuang-13,Jindou-23,Zhoudou-13,Xu-0705,Fendou-79,Zhoudou-19 and Willimas82 et al..We found a number of hybrid combinations with high specific combining ability(SCA)by measuring the special combining ability of the four groups of NCII experiments:Zhonghuang-13×Jindou-23,Shanning-14×Jindou-17,Zhoudou-13×MN413 and Xu-0705×Willimas82.The results showed that the SCA was significantly correlated with the MPH(Mid-parents heterosis),HPH(High-parents heterosis)and OSH(Over-standard heterosis)(P<0.01).In addition,the concept of genotype combining ability is proposed.The correlation analysis of genotype and phenotypic combining ability of four groups of NCII experiments based on yield phenotype showed that genotype combining ability and phenotypic combining ability were significantly correlated.Combing ability based on phenotype and combing ability based on genotypes were significantly correlated(P<0.01).Combing ability based on genotypes can be used to predict heterosis as combing ability based on phenotypes.6.Field natrual insect pollinators for outcrossing of male-sterile linesThe field natrual insect pollinators in Taiyuan were observated.Natural insect species which visited soybean flower included six orders and 11 families.The major natural insect species were Hymenoptera,including China bee,Mellifera bee and Bumblebee of Branch Apidae,Northern-cutting bee,Finely cutting Bee and Yellow phosphorus cutting bee of Branch Megachilidae and Corn belt hair bee and Vestitohalictus pseudovestitus of Branch Halictidae.The insect appeared most frequently in soybean field was the China bee,followed by Mellifera and Northern-cutting bee,the other five bees were minorities.The bee species visiting soybean flowers may be any time during the day with the peak time at 12:00-13:00.7.Analysis of key factors related to outcrossing of cytoplasmic-nuclearmale-sterile lines in soybeanThe present study investigated key factors related to outcrossing of cytoplasmic-nuclearmale-sterile lines in soybean.The first key for commercial hybrid seed production in soybean is sufficient exogeneous viable and effective pollen source for pollinating CMS lines.But we found that the large amount of pollens are not necessarily viable and effective for the morning dew causes germination of the pollens on anther in Nanjing.The suitable seed nursery place should be selected in areas and seasons without morning dew interference,such as Taiyuan.The second key for commercial outcrossing productivity in soybean is sufficient insect mediators for pollinating the CMS lines.The pod set rates of CMS lines in the open environment increased 45.2%as compared to net room without bees.The third and most important key for commercial outcrossing productivity in soybean is the to-be-pollinated capacity of the CMS lines.In net room with bees and open field with natural insect population,the outcrossing rate(pod set rate)varied greately,from less than 10.0%to more than 99.0%.The superior CMS line(SXJLCMS1A)and can get almost 100.0%pod set rate,while under open field conditions with enough natural insect pollinators.