Identification Of QTL Associated With Soybean Agglutinin (SBA) Content In Muti-environment And Muti-genetic Background

Soybean is an important oil and feed crop,which occupies an important position in national economy.Soybean agglutinin is a kind of bioactive proteins,account for about 5-7% in soybean storage protein,and plays an important role in the physiological process as identify and adhesion between cells、defense against pathogens invasion and symbiotic nitrogen fixation etc.In addition,Soybean agglutinin is one of the main antinutritional factors in soybean food and animal feed,which has harmful effect to the growth of eaters even toxic,and affect the edible safety of soybean products seriously.Hence,Soybean agglutinin content and its activity has become the important indicator in the evaluation of soybean food and feed product safety.Soybean agglutinin activity is damaged and reduced in the process of heating 、 seed germination or fermentation.Excessive machining process will cause damage and the loss of other nutrients inevitably,and increase the production cost and energy consumption.Therefore,to reduce the SBA content of soybean seed has become the most direct and effective means to solve the contradiction.Based on the use of germplasm resources and innovation,soybean varieties of low SBA content could be used directly to provide food and feed processing enterprises.In the present study,Hefeng 45 variety with high SBA content（26.25 mg/g）from Heilongjiang province and other three varieties（Zhongdou 27,Dongnong 48 and Taipingchuan blacksoy）with low SBA content（4.22 mg/g,7.50 mg/g and 1.88 mg/g）were crossed respectively.Three recombinant inbred lines populations were used as materials.The SBA content of all RILs was tested by Heamagglutination（Yang Mingliang,2009）in three years.The relativity was analyzed between agronomic traits and SBA content of three RIL populations in three years.The genetic model of SBA content was analyzed in three RIL populations by the major and multiple genes mixed genetic model.The genetic linkage mapping of SBA content was constructed by using SSR markers in three RIL populations.The QTL were identified in the three RIL populations for SBA content.The results were as follows:（1）High linear correlation existed between haemagglutination activity and concentration of SBA.Linear equation was Y=2.4194X-239.19,correlation coefficient was R2=0.9609.Haemagglutination activity compared between test samples to standard samples of SBA,then the concentration of standard sample was used to calculate the content of test sample.Provided areliable method for quantitative detection of SBA.The method has higher precision and accuracy,and the operation is simple and low cost.It was suitable for large group germplasm screening and offspring phenotype analysis.（2）Significant correlations existed between SBA content and main agronomic traits or quality traits.The correlation performance was different in each year in different RIL populations.The results showed that SBA content was negatively related to protein content,and there was a stable positive correlation relationship between grain weight per plant and grain number in almost all environments.These results had important guiding significance for the development of low SBA content,high protein content and high yield soybean varieties.（3）Genetic model of SBA content conformed to the 2 main gene + polygene mixed genetic model.The main genetic form and effect value had different performance with the optimal genetic model in all populations and environments.The optimal genetic model for HT-RIL population was E-2-1,E-1-5 and E-2-1 respectively in all environments.The rate of main gene was 69.37%,58.37% and 62.46% respectively.The rate of polygene was 24.33%,37.55% and 26.63%respectively.The optimal genetic model for HT-RIL population was E-1-3,E-2-2 and E-2-3respectively in all environments.The rate of main gene was 73.99%,55.78% and 74.05%respectively.The rate of polygene was 19.73%,38.54% and 19.80% respectively.The optimal genetic model for HT-RIL population was E-1-3,E-1-2 and E-2-6 respectively in all environments.The rate of main gene was 54.73%,64.3% and 49.27% respectively.The rate of polygene was32.61%,23.64% and 36.04% respectively;The rate of major gene was higher than polygenic significantly.（4）Three molecular genetic linkage maps had been constructed with SSR markers in three RIL population respectively.Hefeng 45 and Taipingchuan blacksoy were crossed,and 201 RILs were drived,named as HT-RIL population.The genetic map contained 12 linkage groups（LG）with 134 polymorphic SSR markers,SSR markers covered the chromosome length was about 1252.9 c M.The average length and covered 9.78 c M.Hefeng 45 and Dongnong 48 were crossed,and 189 RILs were drived,named as HD-RIL population.The genetic map contained 13 LGs with 129 polymorphic SSR markers,and covered 1296.5 c M.The average length between Markers was10.07 c M.Hefeng 45 and Zhongdou 27 were crossed,and 167 RILs were drived,named as HZ-RIL population.The genetic map contained 15 LGs with 185 polymorphic SSR markers,and covered 2054.7 c M.The average length between Markers was 11.25 c M.（5）The analysis of SBA content QTLs had been conducted by three RIL populations in three environments.A total of 16 QTLs related to SBA content wee identified,and assigned to A1,C1,C2,D1 a,D1b,K and H LGs.The three RIL populations had similar linkage group interval in A1,C1 and D1 b linkage groups.Three QTL were detected to have same marker interval:Satt300-Satt545,Satt139-Sat₀42 and Satt189-Satt537.The markers that were sloser to SBA content QTL were Satt300,Satt139 and Satt189.These markers had great genetic effect to increase SBA content,which have potential applications in marker-assisted selection.Sba HDC2-1 andSba HZK-1 were from C2 LG of HD-RIL population and K LG of HZ-RIL population respectively.And these two QTLs were from two groups of male parent,detected twice in three years.The values of additive effect were negative,implying that the genetic effect of QTL characterized the reduction of SBA content significantly,and the genetic contribution rate was high and stable.So,these QTLs had moreapplied value in the low content of SBA marker-assisted selection.（6）14 QTLs that associated with SBA content were detected with additive effect in three RIL populations and three environments.Among them,10 loci derived from the female parent Hefeng45 had additive effect to increase SBA content dominatingly.4 loci derived from different male parents in three RIL populations had additive effect to reduce SBA content dominatingly.The genetic effect of SBA content dominated mainly by additive effect,and explained higher phenotypic variation from 2.19% to 17.26%.The genetic contribution rate of additive and environment interaction effect was not too high for SBA content,and the variation range was from0.15% to 3.33%.These were affected by the different RIL populations and environments.（7）In all RIL populations and environments,23 pairs of epistatic QTL loci were found,and associated with SBA content.Among them,11 pairs of epistatic QTL were parental type that increased SBA content,and 12 pairs of epistatic QTL were recombinant type that reduced SBA content.The epistatic effect took place between two linkage group in A1,C1,D1 b,D1a,K,H and C2 respectively.Among them,four stable pairs of epistatic QTL,Sba HZA1-1 × Sba HZD1b-1,Sba HZC1-1 × Sba HZD1b-1,Sba HDD1a-1 × Sba HDA1-2 and Sba HTA1-1 × Sba HTC1-1 were detected respectively.The interaction linkage markers were Satt300-Satt545 × Satt189-Satt157,Satt139-Sat₀42 × Satt189-Satt157,Satt402-Satt198 × Satt382-Satt155 and Satt545-Satt300 ×Satt139-Satt578,respectively.The interaction chromosome was A1×D1b,C1×D1b,D1a×A1 and A1×C1,respectively.The stabile epistatic QTL laid a foundation for its further application in breeding practice.