Drought stress‐induced changes in the composition and physical state of phospholipids in wheat

Seedlings of winter wheat ( Triticum aestivum L. cv. Jubilejnaja 50) were grown under normal and dry conditions. Frost resistance (LT 50 ) of 10‐day‐old control seedlings was −6°C. LT 50 of the subsequently drought‐stressed leaves shifted to −16°C. In plants of the same physiological age (28 days) but grown without stress, LT 50 was −12°C. Phosphatidylcholine accumulated and phosphatidylethanolamine decreased in drought‐stressed leaves. Fatty acid unsaturation of these phospholipids increased with leaf age, independently of water supply. Both ageing and drought stress produced a decrease in the apparent phase separation temperature of isolated total phospholipids as determined by electron spin resonance. The possible role of dehydration‐induced structural changes in the bilayer matrix in triggering adaptive alterations in membrane composition, similar to those observed during cold hardening, is discussed.