| Soybean is an important economical crop, which is the major plant protein and oil for people consumption, and material of feeding stuff. Nowadays, the varieties of high fatty acids soybean, can not afford the need of people's life and production. Therefore, it is imperious demand to use modern breeding technology to modify the content of fatty acids in soybean. Fatty acids are quantitative traits which were controlled by many genes. It has important meaning for breeding application to map these quantitative traits in soybean linkage groups.The population of 154 recombination inbred lines derived from the cross of America cultivar Charleston and Chinese elite line Dongnong 594. Fatty acids content of the population, planted in three different sites, were analyzed during 2007 to 2009. QTL that underlying Fatty Acids content of soybean were found.1. This paper improved the analysis method, the rapid determination on fatty acids content by Gas Chromatography(GC) in Soybean. The grinded soybean meal was used as material for saponification and methyl esterification directly, then measured by chromatography column HP519091J-413. The results showed that: the peak time of palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid were 6.57, 7.83, 8.73, 8.86, and 9.06 min. The advantages of this method fast, operating easily, and medicine-saving. Furthermore, it could obtain good results with few samples, which is difficult to recover the lipids from common ways.2. Five kinds of fatty acid contents of 154 F14 and F15 lines crossed by Charleston(♀)×Dongnong594(♂) were measured by GC under the condition of three years and three sites. The QTL of fatty acids contents were analyzed with method of composite interval mapping (CIM) by Win QTL Cartographer 2.5. In total, 68 related QTL distributed on the 18 linkage groups were obtained. 20 QTLs were detected in different years or different sites, including 3 QTLs related with palmitic acid contents, qPal-C2-2,qPal-A1-1 and qPal-N-1; 5 QTLs related with stearic acid contents, qSt-B1-1, qSt-B1-2, qSt-D1a-1, qSt-C2-1 and qSt-F-1; 5 QTLs related with oleic acid contents, qOle-B2-1,qOle-C2-3,qOle-G-1,qOle-H-1 andqOle-M-1; 4 QTLs related with Linoleic acid contents, qLin-B1-1,qLin-C2-1,qLinN-1 and qLin-H-1, and 3 QTLs related with Linolenic acid contents, qLino-B1-1, qLino-C2-1, and qLino-J-1. These stable QTLs laid the foundation for specific fatty acid contents breeding by marker-assisted selection.68 underlying fatty acids content QTLs were mapped under the 3 years and 3 sites. Among them, 48 QTLs were located in one environment, 20 were detected repeatedly. The results implied that different QTL controlled the expression of soybean fatty acid content and the fatty acid content of soybean QTLs underdifferent environmental conditions.3. 19 were environmental interaction QTLs and 45 pairs epistatic QTLs, related with soybean under 7 environments of 3 years and 3 sites, were located on eighteen linkage groups. 8 pairs epistatic QTLs were related with soybean palmitic acid contents, and 8 pairs epistatic QTL were related with soybean stearic acid contents. 12 pairs epistatic QTLs were related with soybean oleic acid contents. 11 pairs epistatic QTLs were related with soybean linoleic acid contents in all linkage groups. In these epistatic loci, the vast majority occured in two different linkage groups, or in a linkage group on two sites, it also found that with a locus were interacted with many QTL loci. It confirmed the extension and complexity of epistatic way. Major effect QTLs, involved in the epistatic, confirmed the main effect and epistatic QTLs is the genetic basis of quantitative traits. 4. It reached very significant of five fatty acids content among varieties from different regions in Northeast China, and a more visible trend was found in the regional distribution. The trends of palmitic acid and oleic acid distribution were Heilongjiang > Jilin > Liaoning. Stearic acid and linoleic acid distribution were Liaoning >Jilin>Heilongjiang. And linolenic acid distribution were Liaoning >Jilin>Heilongjiang.Correlation analysis results of fatty acid composition: palmitic acid and stearic acid was significantly negatively correlated (r = - 0.57, r = - 0.56) with linoleic acid content. Palmitic acid was positively correlated with oleic acid and negatively correlated with linolenic acid, but they are not significant negative correlation. Stearic acid was negatively correlated with oleic acid (r = -0.853), but none were significant negative correlation. Oleic acid was negatively correlated with linoleic acid (r = - 0.47).33 SSR markers were associated with the fatty acids composition. 12 SSR markers were associated with palmitic acid; 13 markers were associated with stearic acid, 18 SSR markers were associated with oleic acid, 18 SSR markers were associated with linoleic acid, and 16 SSR markers were associated with linolenic acid QTLs. In this study, the QTLs isolated or tightly linked molecular markers can be used for marker-assisted selection of soybean quality breeding.The paper obtained the Innovation in the following:1. Improved methods for papid Determination of soybean fatty acid. For the first time using the column HP519091J-413 in the analysis of soybean fatty acids, and it was easy to operate, less sample, and short analysis times.2. In multiple years and and sites, the mapping 68 QTLs of the fatty acid content of soybean, of which were repeatedly detected, 20 QTLs, will minimize the environmental impact factors, many QTLs were detected and screened with SSR markers closely linked; and detected 45 pairs of epistatic QTL fatty acids, 19 QTLs of interaction with the environment. These results were important in soybean molecular breeding with specific fatty acids.
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