Lipid and Surface Wax Synthesis in Water-stressed Cotton Leaves

The incorporation of 2-¹⁴C]malonate and 1-¹⁴C]acetate into internal lipid and surface wax by cotton leaves (Gossypium hirsutum L. `Deltapine') having water potentials of −8 to −15 bars (controls) and −19 to −32 bars (water-stressed) was compared. Lipid from stressed leaves contained a mean of 57% more radioactivity than corresponding controls for five experiments. Acetyl coenzyme A carboxylase was not limiting to fatty acid synthesis in water-stressed cotton leaves at the water potential levels tested, whereas fatty acid synthetase was stimulated. In four of six experiments, wax from stressed leaves contained a mean of 38% less radioactivity than nonstressed leaves when incubated 24 hours after rehydration. Evidence is presented to show that after a suitable period of rehydration, previously stressed cotton leaves produce more wax than leaves prior to stressing.