Effects of Far-red Light on the Labelling of Acyl Lipids during the Greening of Barley (Hordeum vulgare)

Etiolated Hordeum vulgare (barley) Plants were greened under white light or far-red (> 700 nm) light. Exposure to far-red light inhibited chlorophyll synthesis (especially chlorophyll b) and the development of photosystem II which were seen when greening took place under white light. Primary leaves were detached and the labelling of their acyl lipids from [14C]acetate was studied under white light or far-red light illumination. Greening with far-red light caused a reduction in the radiolabelling of polyunsaturated fatty acids and diacylgalactosylglycerol. Total fatty acid labelling rates were unaffected. Phosphatidylethanolamine, which was normally poorly labelled, accounted for up to 15 per cent of the total radioactivity in acyl moieties of lipids in leaves greened with far-red light. The results are discussed in connection with the role that acyl lipids may play in normal thylakoid structure and function.