|HEIM, CRYSTAL - University Of Missouri
Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2016
Publication Date: 1/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5607534
Citation: Heim, C.B., Gillman, J.D. 2017. Genotyping-by-sequencing-based investigation of the genetic architecture responsible for a ~sevenfold increase in soybean seed stearic acid. G3, Genes/Genomes/Genetics. 7:299-308. doi:10.1534/g3.116.035741.
Interpretive Summary: Soybean oil has historically been hydrogenated to increase shelf life, increase its applicability for baking and margarine, and increase oil tolerance to cooking/frying. The formation of trans fat during chemical hydrogenation has been linked conclusively to serious health concerns, and the FDA has recently removed the "Generally Regarded As Safe" stats for trans fat containing foods, and mandated labeling of all foods containing trans fats. Manufacturers have removed hydrogenated soybean oil from many products and the soybean industry has lost a substantial proportion of its market to imported tropical oils as as result. An alternative to chemical hydrogenation or tropical fats is the genetic alteration of soybean to increase seed stearic acid levels, a saturated fat which does not have the same cardiovascular negative associations as other saturated fats or trans fats. In this report, we detail genetic mapping of genes which elevate seed stearic acid levels ~7-fold over those present in typical soybean seeds. This is a first step in introduction of the causative genes into advanced, high yielding soybean cultivars to deliver a more health conscious product.
Technical Abstract: Soybean oil is highly unsaturated and oxidatively unstable, rendering it non-ideal for most food applications. Until recently, the majority of soybean oil underwent partial chemical hydrogenation, a process which produces trans fats as an unavoidable consequence. Dietary intake of trans fat and most saturated fats have been conclusively linked to negative impacts on blood cholesterol levels and cardiovascular health. Two major soybean breeding targets have focused on altering soybean seed oil composition so as to 1) reduce or eliminate the need for chemical hydrogenation, and 2) to replace the functional properties of partially hydrogenated soybean oil. One potential solution to these problems is the elevation of seed stearic acid, a saturated fat which has no negative impacts on cardiovascular health, from 3-4% in conventional lines to >20% of the seed oil. We utilized a Genotyping-By-Sequencing based QTL mapping method to elucidate the genetic architecture of oil composition in a cross between two mutant soybean lines, one with ~11% stearic acid and another with 24-28% stearic acid. We successfully identified 21 QTL for seven traits, including four QTL for seed stearic acid content.