Choline metabolism in glycinebetaine accumulating and non-accumulating near-isogenic lines of Zea mays and Sorghum bicolor

Salinity resulted in increased accumulation of choline in both glycinebetaine (GB) accumulating and non-accumulating lines. When grown in the presence of NaCl, GB-non-accumulating lines had increased concentrations of choline and phosphocholine, but not GB. Decreased phosphatidylcholine turnover results in an increase in phosphocholine, which then inhibits the activity of N-phosphoethanolamine methyltransferase. The block in GB synthesis in GB non-accumulating lines does not occur at the initial choline oxidation step, and the previously identified bet1 locus does not appear to be choline monooxygenase. However, the lack of GB synthesis does affect synthesis and turnover of choline moieties in GB non-accumulating lines, which may lead to alterations in overall 1-carbon metabolism in plants.