Development of Rigorous Fatty Acid Near-Infrared Spectroscopy Quantitation Methods in Support of Soybean Oil Improvement

The mature seeds of soybean ( Glycine max L. Merr) are a valuable source of high-quality edible lipids and protein. Despite dramatic breeding gains over the past 80 years, soybean oil continues to be oxidatively unstable, due to a high proportion of polyunsaturated triacylglycerols. Until recently, the majority of soybean oil underwent partial chemical hydrogenation. Mounting health concerns over trans fats, however, has increased breeding efforts to introgress mutant and biotechnological genetic alterations of soybean oil composition into high-yielding lines. As a result, there is an ongoing need to characterize fatty acid composition in a rapid, inexpensive and accurate manner. Gas chromatography is the most commonly used method, but near-infrared reflectance spectroscopy (NIRS) can be calibrated to non-destructively phenotype various seed compositions accurately and at a high throughput. Here we detail development of NIRS calibrations using intact seeds for every major soybean fatty acid breeding goal over an unprecedented range of oil composition. The NIRS calibrations were shown to be equivalent to destructive chemical analysis, and incorporation into a soybean phenotyping operation has the potential to dramatically reduce cost and accelerate phenotypic analysis.