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The role of light in soybean seed filling metabolism
Author(s) -
Allen Doug K.,
Ohlrogge John B.,
ShacharHill Yair
Publication year - 2009
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2008.03771.x
Subject(s) - glutamine , asparagine , amino acid , chemistry , biochemistry , glycine , metabolism , flux (metallurgy) , sucrose , chromatography , organic chemistry
Summary Soybean ( Glycine max ) yields high levels of both protein and oil, making it one of the most versatile and important crops in the world. Light has been implicated in the physiology of developing green seeds including soybeans but its roles are not quantitatively understood. We have determined the light levels reaching growing soybean embryos under field conditions and report detailed redox and energy balance analyses for them. Direct flux measurements and labeling patterns for multiple labeling experiments including [U‐ 13 C 6 ]‐glucose, [U‐ 13 C 5 ]‐glutamine, the combination of [U‐ 14 C 12 ]‐sucrose + [U‐ 14 C 6 ]‐glucose + [U‐ 14 C 5 ]‐glutamine + [U‐ 14 C 4 ]‐asparagine, or 14 CO 2 labeling were performed at different light levels to give further insight into green embryo metabolism during seed filling and to develop and validate a flux map. Labeling patterns (protein amino acids, triacylglycerol fatty acids, starch, cell wall, protein glycan monomers, organic acids), uptake fluxes (glutamine, asparagine, sucrose, glucose), fluxes to biomass (protein amino acids, oil), and respiratory fluxes (CO 2 , O 2 ) were established by a combination of gas chromatography‐mass spectrometry, 13 C‐ and 1 H‐NMR, scintillation counting, HPLC, gas chromatography‐flame ionization detection, C:N and amino acid analyses, and infrared gas analysis, yielding over 750 measurements of metabolism. Our results show: (i) that developing soybeans receive low but significant light levels that influence growth and metabolism; (ii) a role for light in generating ATP but not net reductant during seed filling; (iii) that flux through Rubisco contributes to carbon conversion efficiency through generation of 3‐phosphoglycerate; and (iv) a larger contribution of amino acid carbon to fatty acid synthesis than in other oilseeds analyzed to date.