The prokaryotic pathway of lipid synthesis in oat leaf plastids

Evidence for the operation of the prokaryotic pathway of acyl lipid synthesis is an 18:3 plant was sought by incubating plastids from 6 sequential segments from oat seedling leaves as described previously except that {sup 14}C-G3P was used. Proplastids were the most biosynthetically active plastids (x2-3) and DAG and PA were the most heavily labelled acyl lipids (>75% of label). Analysis of MGDG and DGDG molecular species (MS) following pre-incubation with {sup 14}C-G3P (40 mins) and subsequently with UDP{sup 3}H-gal (30 mins), showed that only MS 16:0/18:0 and MS 16:0/18:1 were significantly labelled with {sup 14}C whereas all 5 MS were labelled with {sup 3}H-gal. However most of the {sup 3}H label was in the same MS as the {sup 14}C except when 18:2/18:2 DAG or PC was added with the {sup 3}H-gal, in which case considerably additional {sup 3}H-gal (up to 100%) appeared in the 18:2/18:2 MS of both these lipids.