THE ROLE OF LIPID DESATURATION IN PROTECTION MECHANISM AGAINST TEMPERATURE STRESSES

The sequential elimination of fatty-acid desaturases of membrane glyce rol lipids resulted in mutant strains of cyanobacterium, Synechocystis PCC6803, with well defined fatty-acid compositions. The physiological studies on these strains revealed that polyunsaturated fatty acids ar e essential in adaptation to low temperatures and in tolerance to low- temperature stresses. In contrast to these findings we were able to de monstrate that fatty-acid desaturation has minor if any affect on high -temperature tolerance. The complete elimination of polyunsaturated fa tty-acid enhanced the susceptibility of cells to low-temperature photo inhibition. Our results suggest a determinative role of membrane struc ture in recovery processes following the photoinhibitory inactivation of photosynthetic machinery.