Quantitative Trait Locus Analysis Of Fatty Acids In Two F₂ Populations Of Soybean

Soybean is one of the most important food and oil crops in China,which plays an important role in the development of the national economy.Fatty acid content in soybean is a quantitative trait controlled by multiple genes,and is susceptible to environment.Marker assisted selection based on genotypic information may improve the accuracy and efficiency of selection for the improvement of fatty acid in soybean.Although lots of QTLs?Quantitative Trait Locus?for fatty acids have been reported,QTLs that could be consistently detected in different genetic backgrounds are still very limited.In this study,a low linolenic line,FA10,was used as a common male parent to cross with Zhongdou 32 and Zhongdou 43 to construct two F₂ segregating populations.SSR markers were used to identify QTLs associated with fatty acids to find QTLs that can be detected repeatedly in different genetic backgrounds.The results were as follows:1.A Gas chromatography method for the determination of soybean fatty acids was established.Compared with the external standard method and previous studies,the internal and external standard methods had the good feasibilities.The establishment of GC method for the determination of fatty acid laid the foundation for the QTL analysis.2.Two F₂ populations were constructed,of which Pop1?Zhongdou 32×FA10?consisted of 180 individuals and Pop2?Zhongdou 43×FA10?consisted of 75individuals.One thousand and five SSR markers evenly distributed on 20chromosomes of soybean genome were selected to screen polymorphism between the parents.Two hundred and fifty-three polymorphic markers in Pop1 and two hundred and three markers in Pop2 were used to genotype the two populations.Two genetic linkage maps consisting of 140 markers in Pop1 and 116 markers in Pop2 were constructed by using IciMapping.Fifty QTLs were detected in Pop1 population,of which nine were related to palmitic acid,three were related to stearic acid,four were related to oleic acid,two were related to oleic acid,twenty-one were related to linolenic acid and eleven were related to total fatty acids.Twenty-one QTLs were detected in Pop2 population,of which two were related to palmitic acid,five were related to stearic acid,three were related to oleic acid,three were related to oleic acid,five were related to linolenic acidand and three were related to total fatty acids.3.Among the QTLs detected in this study,four QTLs for linolenic acid were consistently detected in the two populations.Compared with the previous studies,some QTLs for fatty acid were confirmed.Epistasis analysis showed 38 epistatic QTLs for fatty acids were detected in Pop1,of which five were related to palmitic acid,three were related to stearic acid,sixteen wererelated to oleic acid,eight wererelated to linoleic acid,four were related to linolenic acid,and two were related to total fatty acids.Thirty-three epistatic QTLs for fatty acids were detected in Pop2,of which three were related to palmitic acid,one was related stearic acid,three were related to oleic acid,two were related to linoleic acid,and twenty-four were related to linolenic acid.