Diversity of Maize Kernels from a Breeding Program for Protein Quality: II. Correlatively Expressed Functional Amino Acids

Abstract

ABSTRACTModern maize (Zea mays L.) breeding and selection for large starchy kernels may have contributed to reduced contents of essential amino acids, including lysine, methionine, and cysteine, which represents a serious nutritional problem. We evaluated 1348 maize accessions classified into 13 populations and derived from crossing exotic, high‐quality maize landraces with Corn Belt stiff‐ and non‐stiff‐stalk heterotic groups. We used multivariate statistical analyses methods and validated partial least squares regression and structural equation models to study the homeostasis of these amino acids in relation to other phytochemicals in the maize kernel. New insights into the relative importance of several phytochemicals were derived from structural equation modeling, indicating that biochemical and physical constituents had negative impacts on amino acid contents regardless of heterotic group or endosperm texture and that mineral nutrients had positive effects; whereas, color space descriptors had mixed effects depending on heterotic group and endosperm texture. It was possible to develop quality protein germplasm with large lysine (4.2 g kg−1 dry mass) content and opaque endosperm that resembles translucent endosperm, while the conversion from opaque to translucent endosperm was associated with minimal loss of lysine. Accessions derived from DKXL370‐S11, DXKL370‐N11a‐N20, and ‘Nokomis Gold’ populations were identified as sources with high and stable contents of protein and all three amino acids, having either opaque or translucent endosperm textures.