Abstract
Plants are known to have two pathways (prokaryotic and eukaryotic) for galactolipids synthesis each of which has characteristic fatty acid composition for diacylglycerol backbone. Among both, eukaryotic pathway is likely more important for galactolipid synthesis since almost all plants have that pathway. By pulse chase analysis, phosphatidylcholine (PC) has been considered to be an intermediate of eukaryotic galactolipids. Actually, under phosphate-starved condition, characteristic digalactosyldiacylglycerol (DGDG) is accumulated by eukaryotic pathway, and fatty acid composition of the DGDG is very similar to that of PC on outer envelope membrane.
In this study, we focused on PC-specific phospholipase C (PC-PLC). By using EST database, we found that there are homologs of bacterial PC-PLC only in plants. Thus, these homologs may contribute to plant-specific lipid metabolism. There are six homologs in Arabidopsis and we found that expression of only one gene (PC-PLC3) responds to phosphate starvation.
