Activation of galactolipid biosynthesis in development of pistils and pollen tubes

Galactolipids such as monogalactosyldiacylglycerol and digalactosyldiacylglycerol are essential lipids for the proper functioning of photosynthetic membranes. However, the function of galactolipids in flowers is unknown. Previously, we reported that pistils have higher galactolipid-producing activity than leaves. The present study investigated galactolipid biosynthesis in pistils in more detail using Petunia hybrida and Lilium longiflorum. The results showed that digalactosyldiacylglycerol levels increased during flower development. In addition, the galactose incorporation activity into galactolipids was induced, suggesting that the pathway for the production of digalactosyldiacylglycerol was stimulated. Interestingly, a significant increase in galactolipids was also observed in elongated pollen tubes. Therefore, pistils are the main site of galactolipid biosynthesis and whose galactolipid biosynthesis activity is induced during flower development, and this induction includes considerable galactolipid biosynthesis in pollen tubes.