The effect of tobacco plant transformation with a gene for acyl-lipid Δ9-desaturase from Synechococcus vulcanus on plant chilling tolerance

Tobacco plants with the introduced desC gene for acyl-lipid Delta 9-desaturase from the thermophilic cyanobacterium Synechococcus vulcanus were cultivated on agar-solidified Murashige and Skoog, nutrient medium supplemented with ferulic acid and antibiotics at 22 degrees C and a 16-h photoperiod. Control plants were transformed with an empty pGA482 vector. The analysis of fatty acids (FAs) showed that, in transgenic plants, the level of 16:0 and 18:0 FAs decreased substantially, whereas the levels of di- and trienoic FAs increased. Transformed plants were more cold-tolerant. The tolerance to chilling was evaluated from electrolyte leakage from tissues damaged by cold treatments and from the accumulation of a product of lipid peroxidation, malondialdehyde. It was concluded that acyl-lipid Delta 9-desaturase was actively expressed in transgenic tobacco plants and converted stearic acid into oleic acid, thus producing a substrate for further synthesis of di- and trienoic FAs. An increased proportion of polyunsaturated FAs in membrane lipids resulted in improved tobacco plant tolerance to chilling.