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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #324808

Title: Canopy position has a profound effect on soybean seed composition

item Huber, Steven
item LI, KUNZHI - University Of Illinois
item Nelson, Randall
item ULANOV, ALEXANDER - University Of Illinois
item DEMURO, CATHERINE - University Of Illinois
item Baxter, Ivan

Submitted to: PeerJ
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2016
Publication Date: 9/13/2016
Citation: Huber, S.C., Li, K., Nelson, R.L., Ulanov, A., Demuro, C., Baxter, I.R. 2016. Canopy position has a profound effect on soybean seed composition. PeerJ. 4:e2452.

Interpretive Summary: Soybeans are valued for their protein and oil content, but when used for human nutrition the content of minerals such as iron is also critically important. Although soybean seeds appear homogenous, the composition of mature seeds varies depending on the position on the main stem where the pods developed. Seed produced at the top of the canopy tend to have higher protein and less oil compared to seeds from the bottom of the canopy. While the concentration of many minerals does not vary with canopy position, iron concentration is generally 20% higher in seeds from the bottom of the canopy. Soy food products (soy flour, milk and okara) made from seeds from the top or bottom of the canopy reflect this difference in total seed iron concentration. Knowledge of these canopy position effects could have immediate application for human health and nutrition in countries such as Africa where iron is limiting in the diet, and identifies potential targets for future improvement in soybean composition.

Technical Abstract: Although soybean seeds appear homogenous their composition (protein, oil and mineral concentrations) can vary significantly with canopy position. Seeds produced at the top of the canopy have higher concentrations of protein but less oil and minerals such as Mg, Fe, and Cu compared to seeds produced at the bottom of the canopy. Altering the microenvironment within the soybean canopy affected the gradients in protein and oil without altering the distribution of Mg, Fe and Cu, suggesting different underlying mechanisms. Metabolomic analysis of developing seeds suggests that availability of free asparagine may be a positive determinant of storage protein accumulation in seeds. Our results establish a new category of seed heteromorphism and provide an unexpected approach to link agronomic practices to improve human nutrition and health by using seeds from the top and bottom halves of the canopy for different purposes, with seeds produced in the lower half reserved for production of iron-rich soy foods for human consumption.