GALACTOLIPID AND CHLOROPHYLL SYNTHESIS AND CHANGES IN FATTY-ACID COMPOSITION DURING THE GREENING OF ETIOLATED MAIZE LEAF SEGMENTS OF DIFFERENT AGES

The pattern of net chlorophyll synthesis, the changes in the fatty acid composition of both total and individual acyl lipids and the increase in the mono- and digalactosyldiglyceride have been determined during the greening of each of three sequential 2-cm segments cut from the shoots of 5-day old etiolated maize seedlings. The youngest tissue failed to 'green' while progressively older tissues green at progressively faster rates; however the final chlorophyll concentration in these different tissues are very similar. The major changes in the fatty acid composition during 'greening' were the increase in linolenic acid (18 : 3) and the appearance in the older tissues of the trans Δ3 hexadecenoic acid. In both the total lipid and the individual lipids the increases in the proportions of 18 : 3 during illumination decreased with increasing age of the etiolated tissue used, although the actual quantitative increases were similar. The results confirm the thesis that the development status of the etioplast at the onset of illumination will influence the subsequent pattern of etioplast-chloroplast transformation. © 1979.