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Galactolipids in Plant Membranes

  1. Peter Dörmann

Published Online: 15 JAN 2013

DOI: 10.1002/9780470015902.a0020100.pub2

eLS

eLS

How to Cite

Dörmann, P. 2013. Galactolipids in Plant Membranes. eLS. .

Author Information

  1. University of Bonn, Bonn, Germany

Publication History

  1. Published Online: 15 JAN 2013

Abstract

Photosynthetic membranes of plants contain high amounts of galactolipids (monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG)) that are indispensable for the efficiency of photosynthetic light reactions. Galactolipids make up the bulk of the thylakoid membranes, and they are also found as integral constituents of the photosystems I and II. The presence of galactolipids is conserved from cyanobacteria and green algae to plants, in accordance with the endosymbiont theory. However, cyanobacteria and plants use different pathways for the synthesis of galactolipids. The ratio of MGDG to DGDG in the thylakoids is crucial for the stabilisation of the membrane bilayer. Under freezing and drought stress, a certain proportion of MGDG is converted into DGDG and oligogalactolipids to prevent fissions and fusions of chloroplast membranes. When plants are grown under phosphate-limiting conditions, phospholipids are partially replaced by galactolipids in plastidial and extraplastidial membranes, thereby releasing phosphate for other essential cellular processes.

Key Concepts:

  • Galactolipids are phosphorous-free glycoglycerolipids in plants.

  • Galactolipids make up the bulk of photosynthetic membranes.

  • Oxygenic photosynthesis in cyanobacteria and plants depends on the presence of galactolipids.

  • The ratio of the two galactolipids carrying one or two galactoses in the head group is crucial for the maintenance of membrane integrity during stress.

  • Phospholipids in plants are replaced by galactolipids during phosphate deprivation.

Keywords:

  • lipid;
  • galactose;
  • chloroplast;
  • photosynthesis;
  • phosphate