Metabolic control analysis of developing oilseed rape (Brassica napus cv Westar) embryos shows that lipid assembly exerts significant control over oil accumulation.
Metabolic control analysis allows the study of metabolic regulation. We applied both single- and double-manipulation top-down control analysis to examine the control of lipid accumulation in developing oilseed rape (Brassica napus) embryos. The biosynthetic pathway was conceptually divided into two blocks of reactions (fatty acid biosynthesis (Block A), lipid assembly (Block B)) connected by a single system intermediate, the acyl-coenzyme A (acyl-CoA) pool. Single manipulation used exogenous oleate. Triclosan was used to inhibit specifically Block A, whereas diazepam selectively manipulated flux through Block B. Exogenous oleate inhibited the radiolabelling of fatty acids from [1-(14)C]acetate, but stimulated that from [U-14C]glycerol into acyl lipids. The calculation of group flux control coefficients showed that c. 70% of the metabolic control was in the lipid assembly block of reactions. Monte Carlo simulations gave an estimation of the error of the resulting group flux control coefficients as 0.27±0.06 for Block A and 0.73±0.06 for Block B. The two methods of control analysis gave very similar results and showed that Block B reactions were more important under our conditions. This contrasts notably with data from oil palm or olive fruit cultures and is important for efforts to increase oilseed rape lipid yields.
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Mingguo
M
Tang
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Irina A
IA
Guschina
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Paul
P
O'Hara
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Antoni R
AR
Slabas
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Patti A
PA
Quant
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
Tony
T
Fawcett
School of Biosciences, Cardiff University, Cardiff CF10 3AX, UKDepartment of Biological Sciences, Durham University, Durham DH1 3LE, UKDepartment of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
John L
JL
Harwood
D000214:Acyl Coenzyme A / Q000378:metabolism; D029688:Brassica napus / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism*; D002250:Carbon Radioisotopes; D003975:Diazepam / Q000494:pharmacology; D005229:Fatty Acids, Monounsaturated; D008055:Lipids / Q000096:biosynthesis* / Q000145:classification; D055432:Metabolomics / Q000379:methods*; D019301:Oleic Acid / Q000494:pharmacology; D010938:Plant Oils / Q000378:metabolism*; D000074262:Rapeseed Oil; D012639:Seeds / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014260:Triclosan / Q000494:pharmacology
D000214:Acyl Coenzyme A; D002250:Carbon Radioisotopes; D005229:Fatty Acids, Monounsaturated; D008055:Lipids; D010938:Plant Oils; D000074262:Rapeseed Oil; D019301:Oleic Acid; D014260:Triclosan; D003975:Diazepam