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

Planta. 2004 Sep;219(5):827-35. doi: 10.1007/s00425-004-1273-y. Epub 2004 Apr 24.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassica napus / growth & development
  • Brassica napus / metabolism*
  • Flowers / physiology
  • Glycerol / metabolism*
  • Glycerophosphates / metabolism*
  • Kinetics
  • Seeds / physiology*
  • Triglycerides / biosynthesis*

Substances

  • Glycerophosphates
  • Triglycerides
  • alpha-glycerophosphoric acid
  • Glycerol