Association studies and QTL mapping for soybean oil content and composition

Soybean oil is one of the most important vegetable oils in world. Increasing oil content and improve its composition is an important aim of many soybean breeding programs. In this context, the objective of this study was to identify QTLs controlling oil and fatty acid contents in soybean seed in different locations. For this, we developed F-2-derived populations by crossing CS303TNKCA and FA22 lines, and analyzed oil and fatty acid content in four locations in Brazil. We evaluated the correlations of traits in each location and between locations and used 1536 SNPs to molecular characterize this population. QTLs associated with the average values of four environments were identified by using simple interval mapping. A linkage map was generated using 534 SNP markers, and 25 linkage groups were formed. A total of 20 QTLs controlling oil, palmitic, stearic, oleic, linoleic and linolenic contents were found, varying from one (linolenic content) to six (palmitic content), and explaining from 7.02% (qSte-13) to 70.37% (qLin-14) of phenotypic variation. We could not associate eight QTLs (qPal-02, qOle-02, qLol-02, qOle-04, qLol-04, qPal-13.2, qSte-15 and qSte-17) with reported QTLs and genes, so these could be set as new QTLs controlling fatty acid composition. The results found in the present work can help understand the genetic basis of these traits and help breeders to modify oil content and composition in soybean seed, especially in tropical conditions.

Automated summary

This study aimed to identify QTLs controlling oil and fatty acid contents in soybean seed in different locations. By analyzing molecular characterization of the population, linkage mapping and SNP markers, a total of 20 QTLs controlling oil and fatty acid contents were identified, including some potentially new QTL associated with fatty acid composition. These results could aid in understanding the genetic basis of these traits and assist breeders in modifying oil content and composition in soybean seed, especially in tropical conditions.