Increased levels of glycerol-3-phosphate lead to a stimulation of flux into triacylglycerol synthesis after supplying glycerol to developing seeds of Brassica napus L. in planta.
Glycerol-3-phosphate (glycerol-3P) is a primary substrate for triacylglycerol synthesis. In the present study, changes in the levels of glycerol-3P during rape (Brassica napus L.) seed development and the influence of manipulating glycerol-3P levels on triacylglycerol synthesis were investigated. (i) Glycerol-3P levels were high in young seeds and decreased during seed development at 30 and 40 days after flowering (DAF), when lipid accumulation was maximal. (ii) To manipulate glycerol-3P levels in planta, various concentrations of glycerol were injected directly into 30-DAF seeds, which remained otherwise intact within their siliques and attached to the plant. Injection of 0-10 nmol glycerol led to a progressive increase in seed glycerol-3P levels within 28 h. (iii). Increased levels of glycerol-3P were accompanied by an increase in the flux of injected [14C]sucrose into total lipids and triacylglycerol, whereas fluxes to organic acids, amino acids, starch, protein and cell walls were not affected. (iv) When [14C]acetate was injected into seeds, label incorporation into total lipids and triacylglycerol increased progressively with increasing glycerol-3P levels. (v) There was a strong correlation between the level of glycerol-3P and the incorporation of injected [14C]acetate and [14C]sucrose into triacylglycerol. (v) The results provide evidence that the prevailing levels of glycerol-3P co-limit triacylglycerol synthesis in developing rape seeds.
Vigeolas
Helene
H
Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Golm, Germany.
Geigenberger
Peter
P
D029688:Brassica napus / Q000254:growth & development / Q000378:metabolism*; D035264:Flowers / Q000502:physiology; D005990:Glycerol / Q000378:metabolism*; D005994:Glycerophosphates / Q000378:metabolism*; D007700:Kinetics; D012639:Seeds / Q000502:physiology*; D014280:Triglycerides / Q000096:biosynthesis*
D005994:Glycerophosphates; D014280:Triglycerides; C029620:alpha-glycerophosphoric acid; D005990:Glycerol