Canopy position has a profound effect on soybean seed composition.
Although soybean seeds appear homogeneous, their composition (protein, oil and mineral concentrations) can vary significantly with the canopy position where they were produced. In studies with 10 cultivars grown over a 3-yr period, we found that seeds produced at the top of the canopy have higher concentrations of protein but less oil and lower concentrations of minerals such as Mg, Fe, and Cu compared to seeds produced at the bottom of the canopy. Among cultivars, mean protein concentration (average of different positions) correlated positively with mean concentrations of S, Zn and Fe, but not other minerals. Therefore, on a whole plant basis, the uptake and allocation of S, Zn and Fe to seeds correlated with the production and allocation of reduced N to seed protein; however, the reduced N and correlated minerals (S, Zn and Fe) showed different patterns of allocation among node positions. For example, while mean concentrations of protein and Fe correlated positively, the two parameters correlated negatively in terms of variation with canopy position. Altering the microenvironment within the soybean canopy by removing neighboring plants at flowering increased protein concentration in particular at lower node positions and thus altered the node-position gradient in protein (and oil) without altering the distribution of Mg, Fe and Cu, suggesting different underlying control mechanisms. Metabolomic analysis of developing seeds at different positions in the canopy suggests that availability of free asparagine may be a positive determinant of storage protein accumulation in seeds and may explain the increased protein accumulation in seeds produced at the top of the canopy. Our results establish node-position variation in seed constituents and provide a new experimental system to identify genes controlling key aspects of seed composition. In addition, our results provide an unexpected and simple approach to link agronomic practices to improve human nutrition and health in developing countries because food products produced from seeds at the bottom of the canopy contained higher Fe concentrations than products from the top of the canopy. Therefore, using seeds produced in the lower canopy for production of iron-rich soy foods for human consumption could be important when plants are the major source of protein and human diets can be chronically deficient in Fe and other minerals.
Global Change and Photosynthesis Research Unit, United States Department of Agriculture, Agricultural Research Service, Urbana, IL, United States.|Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.|Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Steven C
SC
Huber
Global Change and Photosynthesis Research Unit, United States Department of Agriculture, Agricultural Research Service, Urbana, IL, United States.|Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.|Lab of Plant Nutrition Genetic Engineering, Kunming University of Science and Technology, Kunming, Yunnan, China.
Kunzhi
K
Li
Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States.|Soybean/Maize Germplasm, Pathology, and Genetics Research Unit, United States Department of Agriculture, Agricultural Research Service, Urbana, IL, United States.
Randall
R
Nelson
Metabolomics Facility, Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
Alexander
A
Ulanov
Global Change and Photosynthesis Research Unit, United States Department of Agriculture, Agricultural Research Service, Urbana, IL, United States.
Catherine M
CM
DeMuro
Plant Genetics Research Unit, United States Department of Agriculture Agricultural Research Service, St. Louis, MO, United States.|Donald Danforth Plant Science Center, Creve Coeur, MO, United States.
Ivan
I
Baxter
Canopy; Elemental composition; Ionome; Nutrition; Physiology; Soybean
New Phytol. 2008;177(2):389-405
18042200
Plant Cell Environ. 2007 Feb;30(2):165-75
17238908
Front Plant Sci. 2014 Sep 03;5:437
25232359
Plant Physiol. 1987 Nov;85(3):841-4
16665787
Nature. 2014 Jun 5;510(7503):139-42
24805231
Plant Physiol. 1986 May;81(1):136-41
16664763
Nutr Rev. 1999 Sep;57(9 Pt 2):S27-33
10568348
Int J Mol Sci. 2013 Mar 26;14(4):6674-89
23531533
J Exp Bot. 2008;59(1):111-9
18093964
Plant Cell Environ. 2013 Mar;36(3):697-705
22943419
Nat Protoc. 2011 Jun;6(6):743-60
21637195
J Exp Bot. 2012 May;63(8):3173-84
22357599
Physiol Plant. 2015 Apr 21;:null
25898948
J Exp Bot. 2005 Jul;56(417):1951-63
15911557
Public Health Nutr. 2009 Apr;12(4):444-54
18498676
Front Plant Sci. 2015 May 13;6:317
26029223
Curr Opin Plant Biol. 2009 Jun;12(3):381-6
19481970
Elife. 2014 May 07;3:e02245
24867639
Front Plant Sci. 2014 Apr 23;5:149
24795736
Metabolites. 2013 May 14;3(2):347-72
24957996
Science. 2006 Nov 24;314(5803):1298-301
17124321
J Agric Food Chem. 2012 Jul 11;60(27):6764-71
22708739
Front Plant Sci. 2014 Apr 03;5:112
24765096
J Agric Food Chem. 2012 Sep 26;60(38):9543-52
22950648