Integration of the cyanobacterial DesA gene for Δ12-acyl-lipid desaturase improves potato tolerance to paraquat-induced oxidative stress

The effect of potato plant (Solanum tuberosum L., cv. Desnitsa) transformation with the desA gene from Synechocystis sp. PCC 6803, encoding Δ12 acyl-lipid desaturase, on the development of plant tolerance to oxidative stress was studied. To initiate oxidative stress, plants were treated with 1 mM paraquat; this treatment enhanced oxidative processes in both wild-type and transformed potato plants via the activation of superoxide anion-radical generation. This resulted in the activated oxidation of membrane lipids and the formation of a great amount of fatty acids with coupled double bonds (conjugated dienes, CD), further breakdown of lipid molecules, and enhanced production of MDA in tissues of wild-type and transformed plants. The characteristics of oxidative stress, including lipid peroxidation, were less pronounced in transformants as compared with wild-type plants. After treatment with paraquat, activities of main antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) were much higher in wild-type than in transformed plants. Thus, expression of inserted heterologous desA gene for Δ12 acyl-lipid desaturase in potato plants resulted in improved tolerance of transformants to oxidative stress due to the more efficient maintenance of stable cell membrane structure functioning, and this permits prevention of electron “jump” to oxygen and, as a result, of accelerated ROS generation. More developed and regularly arranged chloroplast membrane system in transformants may also favor their improved tolerance.