Metabolomic assessment of key maize resources: GC-MS and NMR profiling of grain from B73 hybrids of the nested association mapping (NAM) founders and of geographically diverse landraces

Authors: VENKATESH, TYAMAGONDLUA - Monsanto Corporation; CHASSY, ALEX - University Of California; FIEHN, OLIVER - University Of California; Flint-Garcia, Sherry; ZENG, QIN - Monsanto Corporation; SKOGERSON, KIRSTEN - Monsanto Corporation; HARRIGAN, GEORGE - Monsanto Corporation

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/28/2016
Publication Date: 2/28/2016
Publication URL: https://handle.nal.usda.gov/10113/5209500
Citation: Venkatesh, T.V., Chassy, A., Fiehn, O., Flint Garcia, S.A., Zeng, Q., Skogerson, K., Harrigan, G.G. 2016. Metabolomic assessment of key maize resources: GC-MS and NMR profiling of grain from B73 hybrids of the nested association mapping (NAM) founders and of geographically diverse landraces. Journal of Agricultural and Food Chemistry. 64(10):2162-2172. doi: 10.1021/acs.jafc.5b04901.

Interpretive Summary: Maize (corn) is a leading source of food energy and nutrition to humans and livestock worldwide, as well as an important feedstock for ethanol production and raw material for industrial applications in the United States. The primary composition of the grain (protein, starch, and oil content) is the key driver for the end use of a specific corn lot. However, low-abundance metabolites which are of less nutritional and economic significance, contain minor nutrients and anti-nutrients that are the target of breeding programs. These metabolites include, for example, sugars, amino acids, fatty acids, vitamins, sugar alcohols, and organic acids, all of which feed into biosynthetic pathways and are precursors for the primary macromolecules in the kernel, starch, protein, and oil. These metabolites may play a vital role in understanding kernel development and could be useful in developing improved maize lines. In addition, metabolite profiles are often used in food safety assessments. We surveyed the metabolic profiles of two very diverse maize populations which represent modern maize lines and a collection of historic landraces across the Americas. Our results provide significant information on contributions of conventional breeding to seed metabolite variation, as well as valuable information on key genetic resources for the scientific community. These results are important to breeders, geneticists and biotechnologists who are involved in improving nutritional and compositional quality of maize and as well as regulatory scientists who are involved in proposed applications of metabolomics in food and feed safety assessments.

Technical Abstract: The present study expands metabolomic assessments of maize beyond commercial elite lines to include two sets of publicly available lines used extensively in the scientific community to investigate the genetic basis of complex plant traits or that may serve as a source of new alleles for improving modern maize hybrids. One set included hybrids derived from the nested association mapping (NAM) founder lines, a collection of twenty-five inbreds selected on the basis of genetic diversity. A second set included hybrids derived from a collection of landraces representative of native diversity from North and South America. Grain was harvested from these hybrids grown at a single replicated site in Ithaca, New York, during the 2013 growing season. Metabolomic data acquisition utilized both gas chromatography-time-of-flight mass spectrometry (GC-TOF-MS) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). Results highlighted extensive metabolomic variation in grain from both hybrid sets (NAM- or landrace-derived), but also demonstrated that, within each hybrid set, subpopulations could be differentiated in a pattern consistent with the known genetic and compositional variation of these lines. Correlation analysis did not indicate a strong association of the metabolomic data with grain nutrient composition although some metabolites did show moderately strong correlations with agronomic features such as plant and ear height. Overall, the study provides new and valuable information on metabolomic diversity associated with key genetic resources utilized by the scientific community in the development of new improved maize lines, insights into the extent of metabolomic diversity associated with conventional maize germplasm, and context to proposed applications of metabolomics in food and feed safety.