XVI International Botanical Congess

(Dept. of Crop Science, North Carolina State Univ., Raleigh, NC 27695, USA). We are engaged in an ongoing study to isolate and characterize genes encoding enzymes of the phosphatidylcholine (PC) and phosphatidylethanolamine (PE) biosynthetic pathways as a requisite step toward understanding how plants regulate the synthesis of these important and abundant phospholipids. In soybeans, we have thus far been successful in isolating cDNAs corresponding to each step of the nucleotide pathway of PC biosynthesis: choline kinase (three isoforms), cholinephosphate cytidylyltransferase (two isoforms) and choline/ethanolamine phosphotransferase. Also from soybean, we have obtained full length cDNAs encoding a phospholipid N-methyltransferase and two isoforms of phosphatidylserine decarboxylase. From Arabidopsis, we have characterized cDNAs encoding a phospholipid N-methyltransferase and two isoforms of choline/ethanolamine phosphotransferase. I will review insights we have gained concerning the metabolism of these phospholipids, and highlight those areas in which our results have differed from, or lent support to, previous work in plants and other eukaryotes.