Location: Soil Management ResearchTitle: Diversity of maize kernels from a breeding program for protein quality: II. Correlatively expressed functional amino acids Author
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2014
Publication Date: 9/26/2014
Publication URL: http://handle.nal.usda.gov/10113/59990
Citation: Jaradat, A.A., Goldstein, W. 2014. Diversity of maize kernels from a breeding program for protein quality: II. Correlatively expressed functional amino acids. Crop Science. 54:2639-2662. Interpretive Summary: Improving essential amino acids and protein contents in corn will improve the livelihoods of many people around the world. High protein, high lysine, and hard seed are important corn breeding objectives. However, the slow progress in improving grain protein and amino acid contents was attributed to their low heritability and to a lack of natural genetic variation among modern corn varieties. We developed a procedure to identify corn genotypes which combined hard seed, large protein and essential amino acids contents. We selected corn genotypes which can be used to develop corn varieties with increased nutritional quality. Also, these genotypes can be used by farmers as feed sources without the need for expensive amino acid supplements.
Technical Abstract: Modern maize breeding and selection for large starchy kernels may have contributed to reduced contents of essential amino acids which represents a serious nutritional problem for humans and animals. The improvement of low levels of essential amino acids, while maintaining high protein content and hard endosperm, remains a breeding challenge in maize. We evaluated the complex genetic structure of 1,348 accessions in 13 maize populations with diverse genetic background of two heterotic groups having opaque (38.7%) or translucent (61.3%) endosperm for the amino acids LYS, MET and CYS. We employed multilevel and multivariate statistical analyses methods; and calibrated and validated partial least squares regression and structural equation models to study homeostasis of the three correlatively expressed functional amino acids. Based on their amino acid contents, the opaque and translucent accessions, respectively, were 68.5 and 79.5% correctly classified. The germplasm provided adequate variation in endosperm texture and hardness to identify direct and indirect effects of multiple phytochemicals, color, and physical components of the maize kernel on these amino acids. Depending on the heterotic group, kernel density which is implicated in LYS content, had positive, negative or no significant effect on LYS estimation in opaque endosperm, but did not substantially improve its estimation in translucent endosperm. We elucidated the factors that accounted for maximum variation in the content of individual and all three amino acids at the heterotic group, population, genotypic and endosperm-texture levels, and identified opaque and translucent genotypes with adequate hardness, and high and stable contents of all three amino acids in both heterotic groups.