Genetic architecture of the seed stearic acid trait in Soybean : QTL mapping and correlations with ten other traits using next-generation sequencing methods

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Soybean seed oil is widely utilized as vegetable oil. However, it is primarily comprised of unsaturated fat and tends to go rancid at normal storing temperatures. The oil can be treated to increase the shelf life, but the process creates trans fats, making soybean oil extremely unhealthy. Soybean oil high in saturated fat would not need to be treated in this way. Saturated fat is also generally considered to be unhealthy. However, there is a "heart-neutral" saturated fat called stearic acid that exists in typical soybean oil at 3-4% of the total oil. A soybean line called A6 has ~28% of this heart-neutral saturated fat. Unfortunately, A6 is extremely difficult to grow, probably because it has a ~1/8 of a chromosome deletion. Within this huge deletion is a gene called SACPD-C that, when it loses function, increases stearic acid to 12-14% of soybean oil. Interestingly, when A6 (1/8 chromosome deletion) is crossed to a line with 12-14% stearic acid (SACPD-C mutation alone), resulting individuals can show even higher stearic acid levels than A6, with the same mutation in SACPD-C as the line with 12-14% stearic acid. This must mean that there is another gene (or multiple other genes) along with SACPD-C affected in A6 that raise the stearic acid levels to 28%. The goal of this research is to locate the other regions in the genome that are contributing to this elevated stearic acid trait. The trait can then be bred into soybean lines that are more viable for farmers to grow, introducing healthier and more stable soybean oil into the market.