Abstract
Phospholipids represent the highly conserved structural basis of biological membranes from bacteria to humans. However, plants and other photoautotrophic organisms are unique in using non-phosphorus galactolipids as primary components of their photosynthetic membranes. In light of the biomass of green tissues as compared with that of the overall plant body and the highly stacked thylakoid membrane structures in chloroplasts, galactolipids are the most abundant membrane lipids on the earth. Historically, the roles of galactolipids have been studied mainly in relation to photosynthesis, and recent advances in molecular biology with Arabidopsis and other model organisms have revealed an essential role of galactolipids in photosynthesis. However, these galactolipids are also abundant in non-photosynthetic organs, especially flowers, which suggests their distinct role apart from photosynthesis. The aim of this mini-review is to describe distinct biochemical properties of flower galactolipids and possible new roles, with a summary of the current understanding of galactolipid biosynthesis in Arabidopsis.