Genetic basis of kernel nutritional traits during maize domestication and improvement

Abstract

Summary The nutritional traits of maize kernels are important for human and animal nutrition, and these traits have undergone selection to meet the diverse nutritional needs of humans. However, our knowledge of the genetic basis of selecting for kernel nutritional traits is limited. Here, we identified both single and epistatic quantitative trait loci (QTLs) that contributed to the differences of oil and carotenoid traits between maize and teosinte. Over half of teosinte alleles of single QTLs increased the values of the detected oil and carotenoid traits. Based on the pleiotropism or linkage information of the identified single QTLs, we constructed a trait–locus network to help clarify the genetic basis of correlations among oil and carotenoid traits. Furthermore, the selection features and evolutionary trajectories of the genes or loci underlying variations in oil and carotenoid traits revealed that these nutritional traits produced diverse selection events during maize domestication and improvement. To illustrate more, a mutator distance–relative transposable element (TE) in intron 1 of DXS2, which encoded a rate‐limiting enzyme in the methylerythritol phosphate pathway, was identified to increase carotenoid biosynthesis by enhancing DXS2 expression. This TE occurs in the grass teosinte, and has been found to have undergone selection during maize domestication and improvement, and is almost fixed in yellow maize. Our findings not only provide important insights into evolutionary changes in nutritional traits, but also highlight the feasibility of reintroducing back into commercial agricultural germplasm those nutritionally important genes hidden in wild relatives.

Eleven biosynthetic genes explain the majority of natural variation for carotenoid levels in maize grain

“…Structural variation in the identified genetic regions also merits further examination. A mutator distance-relative transposable element (TE) in the first intron of maize dxs2 was recently identified to affect expression of dxs2, which was in turn positively correlated with total carotenoid content (FANG et al 2020). This TE had been present in teosinte; appears to have been subject to selection during maize domestication and improvement; and was found to be nearly fixed in the yellow-grain maize lines examined.…”

Genetic analysis of three maize husk traits by QTL mapping in a maize-teosinte population

“…All the three husk traits in the MX population exhibited a broad range of phenotypic variation with normal distribution. The genetic analysis showed that the heritability of three husk traits is fairly high, indicative of superior genetic effect in this population studied [ 33 ]. In addition, except for environment variation, none of significant difference were detected in genetic or interaction between genetic and environment within RILs.…”

The utility of metabolomics as a tool to inform maize biology

“…The evolutionary trajectories of the genes or QTLs responsible for variations in oil and carotenoid traits revealed that these traits caused diverse selection events during maize domestication. This indicates the complex selection patterns of the genes that underlie maize kernel nutritional traits and shows that teosinte alleles can also be valuable for improving those traits ( Fang et al., 2020 ).…”