Compositional variation in trans-ferulic, p-coumaric, and diferulic acids levels among kernels of modern and traditional maize (zea mays l.) hybrids

Authors: ZAVALA-LÓPEZ, MARIANA - Technologico De Monterrey; Flint-Garcia, Sherry; GARCIA-LARA, SILVERIO - Technologico De Monterrey

Submitted to: Frontiers in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2020
Publication Date: 12/22/2020
Citation: Zavala-López, M., Flint Garcia, S.A., Garcia-Lara, S. 2020. Compositional variation in trans-ferulic, p-coumaric, and diferulic acids levels among kernels of modern and traditional maize (zea mays l.) hybrids. Frontiers in Nutrition. 7. Article e600747. https://doi.org/10.3389/fnut.2020.600747.
DOI: https://doi.org/10.3389/fnut.2020.600747

Interpretive Summary: Maize (corn) is a major source of calories in the human diet around the world, is used as feed for livestock, and is a raw ingredient for industrial processes. There are thousands of chemical compounds in the grain which play vital roles in plant growth and defense, grain utilization, and human consumption and nutrition. One group of compounds are the phenolic acids, which are famous for their antioxidant properties associated with human health. Maize is an extremely diverse crop species, adapted to all parts of the world. It is important to understand the diversity within the species to maximize its utilization and to continue improving corn for these various applications. We conducted a detailed study to quantify several phenolic compounds in a set of varieties representing modern corn from around the world and in a set of varieties representing traditional landraces which are grown locally across the Americas. For each phenolic compound we studied, we found a wide range of variation within the modern varieties and within the traditional varieties, and we found very similar ranges of variation between these two groups of varieties. This tells us that the breeding process has not greatly affected these phenolic compounds during the transition from traditional landraces to modern varieties, and that a wide range of variation can be found for phenolic compounds. Because these varieties are common genetic resources for the scientific community, our findings are important to breeders, geneticists and other plant scientists who study the genetics of phenolic compound production and the role of phenolic compounds in various biological processes.

Technical Abstract: Maize is one of the most heterogenous cereals worldwide in terms of yield, physical characteristics, and biochemical composition due to its natural diversity. Nowadays the use of maize hybrids is extensive, while the use of landraces is mostly local. Both have become an important genetic resource useful to identify or generate varieties with desirable characteristics to overcome challenges of agronomic performance, nutritional quality, and functionality. In terms of functionality, one of the most studied families of compounds are phenolic acids. These compounds have been associated with the improvement of human health because of their antioxidant capacity. To evaluate the diversity of phenolic compounds in maize, two collections, the Nested Association Mapping (NAM) founders and 24 landraces, were crossed with B73. Phenolic compounds were extracted and quantified by HPLC-PDA. Soluble and cell wall phenolic acids were identified and significant differences between and within the NAM and Landrace collections were assessed. Soluble p-coumaric acid quantification of B73 × NAM hybrids presented high variation as the range went from 14.45 to 132.34 µg/ g dw. In the case of B73 × Landrace hybrids, wide variation was also found, ranging 25.77–120.80 µg/g dw. For trans-ferulic acid, significant variation was found in both hybrid groups: B73 × NAM presented an average of 157.44 µg/g dw (61.02–411.13 µg/g dw) whereas the B73 × Landrace hybrids average was 138.02 µg/g dw (49.32–476.28 µg/g dw). In cell wall p-coumaric acid, a range from 30.93 to 83.69 µg/g dw and 45.06 to 94.98 µg/g dw was found for landrace and NAM hybrids, respectively. For cell wall trans-ferulic acid, a range from 1,641.47 to 2,737.38 µg/g dw and 826.07 to 2,536.40 µg/g dw was observed for landrace and NAM hybrids, respectively. Significant differences between hybrid groups were found in p-coumaric acid, for both soluble and cell wall-bounded. Therefore, maize hybrids produced by conventional techniques using both modern and traditional varieties showed a high diversity in terms of phenolic compounds, denoting the role of these compounds in the maize ability to endure different environment conditions. This study provides a platform of comparison through the unveiling of maize phenolic compounds for future breeding efforts.