Metabolic flux maps comparing the effect of temperature on protein and oil biosynthesis in developing soybean cotyledons

• Published in: Plant, cell and environment Vol. 31; no. 4; pp. 506 - 517
• Main Authors: IYER, VIDYA V, SRIRAM, GANESH, FULTON, D. BRUCE, ZHOU, RUILIAN, WESTGATE, MARK E, SHANKS, JACQUELINE.V
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.04.2008; Blackwell Publishing Ltd; Blackwell
• Subjects: Biological and medical sciences; Biomass; carbon partitioning; Cell biochemistry; Cell physiology; central carbon metabolism; Cotyledon - growth & development; Cotyledon - metabolism; developing soybean cotyledon; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Glycine max - genetics; Glycine max - growth & development; Glycine max - metabolism; malic enzyme; metabolic flux analysis; nuclear magnetic resonance; oxidative pentose phosphate pathway; Plant Oils - metabolism; Plant physiology and development; Plant Proteins - biosynthesis; Plant Proteins - genetics; Temperature; central carbon metabolism; Temperature; Cotyledon; carbon partitioning; metabolic flux analysis; developing soybean cotyledon; oxidative pentose phosphate pathway; Pentose phosphate pathway; Biosynthesis; malic enzyme; Metabolism; nuclear magnetic resonance
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2008.01781.x

Metabolic flux maps developed from ¹³C metabolic flux analysis (¹³C MFA) are effective tools for assessing the response of biological systems to genetic or environmental perturbations, and for identifying possible metabolic engineering targets. Experimental treatments were designed to distinguish between temperature effects prior to, and during incubation in vitro, on primary metabolism in developing soybeans. Biomass accumulation increased with temperature as did carbon partitioning into lipids. The flux through the plastidic oxidative pentose phosphate pathway (pglP) relative to sucrose intake remained fairly constant [~56% (±24%)] when cotyledons were transferred from an optimum growth temperature to varying temperatures in in vitro culture, signifying a rigid node under these conditions. However, pglP flux ranged from 57 to 77% of sucrose intake when growth temperature in planta varied and were cultured in vitro at the same temperature (as the plant), indicating a flexible node for this case. The carbon flux through the anaplerotic reactions catalysed by plastidic malic enzyme (meP), cytosolic phosphoenolpyruvate (PEP) carboxylase and the malate (Mal) transporter from the cytosol to mitochondrion varied dramatically with temperature and had a direct influence on the carbon partitioning into protein and oil from the plastidic pyruvate (Pyr) pool. These results of the in vitro culture indicate that temperature during early stages of development has a dominant effect on establishing capacity for flux through certain components of central carbon metabolism.