Corn kernels rely on a sugar alcohol to fill out properly
Mourad N, Rolletschek H, Langer M, Sanclemente MA, Saint-Fleur M
Crop Improvement
The plump kernels on a sweet corn or popcorn plant in your garden depend on a hidden chemical buffer that keeps the oxygen-starved center of each kernel running smoothly.
The inside of a growing corn kernel is packed so tightly that it gets very little oxygen. Corn deals with this by using an enzyme to park extra chemical energy and sugar in a storage molecule called sorbitol. When researchers disabled that enzyme, kernels ended up smaller and stored less starch, so the sorbitol system turns out to be a real part of how corn grains fill.
Key Findings
Loss of the Sdh1 enzyme cut maize seed weight by 17% and impaired starch accumulation while raising glucose, fructose, and sucrose levels.
Mutant kernels showed disrupted redox balance (higher NADH and NADPH), lower adenylate energy charge, and upregulated oxidative stress genes.
Sdh1 over-expression rescued the small-grain phenotype without producing kernels larger than wild type, and metabolite profiles were reciprocal to the mutants.
chevron_right Technical Summary
Corn kernels use a sugar alcohol called sorbitol, and an enzyme that handles it, to fill out properly in the oxygen-starved interior of the grain. Without the enzyme, kernels came out 17% lighter and starch buildup suffered.
Abstract Preview
Original paper
Sorbitol dehydrogenase aids grain-fill and integrates carbohydrate metabolism with redox in the hypoxic maize endosperm.
Extreme low oxygen is typical of microenvironments inside developing grains, thus requiring metabolic adaptations to hypoxia. Potential contributions from sorbitol dehydrogenase (SDH) are tested he...
open_in_new Read full abstractAbstract copyright held by the original publisher.
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Maize, also known as corn in North American English, is a tall stout grass that produces cereal grain. The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen, and female inflorescences called ears. The ears yield grain, known as kernels or seeds. In modern ...