Article révisé par les pairs
Résumé : Frost-resistant winter cereals actively adapt the fluidity of their membranes to decreasing temperatures. We have attempted to study the membrane lipid changes that are responsible for this adaptation. In the total leaf lipids of winter barley plants (Hordeum vulgare L.) 3 weeks' growth at low temperature (4 °C) decreased the number of double bonds per lipid molecule in all lipid classes extracted from leaves. However, there were only minor changes in the degree of fatty acid unsaturation in the lipids of barley thylakoid membranes during this treatment. In contrast, a significant increase in the lipid/protein ratio was observed in cold-adapted thylakoids when compared with control plants. This cold-induced increase in the lipid/protein ratio seems to act as an adaptive mechanism to maintain fluid membranes despite lower growth temperatures. Cold-hardening also caused a marked increase of the total polar lipids of leaves relative to chlorophyll; this was particularly pronounced for the phospholipids, indicating that the adaptation to low growth temperatures could also be associated with accumulation of extra-chloroplastic material in the cells. © 1984 Oxford University Press.