The role of choline in some metabolic reactions of Nicotiana rustica.

The methyl groups of choline which have been shown to be donated in various reactions in animal metabolism (1, 2) have not been demonstrated to participate in plant methylation reactions. Experiments by Matchett, Kirkwood, and Marion (3, 4), Dubeck and Kirkwood (5), and Sribney and Kirkwood (6), with Hordeum distichum, Ricinus communis, and Dice&a hybrids in which choline was supplied as a possible methyl precursor, indicated that choline methyl groups were not utilized to form the methyl groups of the alkaloids hordenine in barley, ricinine in castor beans, or protopine in Dicentra. It was therefore of interest to examine the metabolism of choline in another plant species. In the present study it was shown that in Nicotiana rustica the methyl carbons of choline could be transferred to give the N-methyl carbon of nicotine. In addition, little choline appeared to enter into phospholipide synthesis.