Effect of the desA gene encoding Δ12 acyl-lipid desaturase on the chloroplast structure and tolerance to hypothermia of potato plants

Effects of the desA gene from the cyanobacterium Synechocystis sp. encoding Δ12 acyl-lipid desaturase and increasing the level of unsaturated fatty acids (linoleic acid (18:2) primarily) in membrane lipids, which was inserted into potato (Solanum tuberosum L., cv. Desnitsa) plants, on chloroplast ultrastructure and plant tolerance to low temperatures were studied. The main attention was focused on modifications in the chloroplast structure and their possible relation to potato plant tolerance to oxidative and low-temperature stresses under the influence to their transformation with the Δ12 acyl-lipid desaturase gene from cyanobacterium (desA-licBM3-plants). Morphometric analysis showed that, in comparison with wild-type (WT) plants, in desA-licBM3-plants the number of grana in chloroplasts increased substantially. The total number of thylakoids in transformant chloroplasts was almost twice higher than in WT plants. The number of plastoglobules per chloroplast of transformed plants increased by 25%. A marked increase in the number of grana, total number of thylakoids, and the number of plastoglobules in chloroplasts of desA-licBM3-plants indicates their more intense lipid metabolism, as compared with WT plants, and this resulted in the conservation of some part of lipids in plastoglobules. In addition, the expression of heterological desA gene encoding Δ12 acyl-lipid desaturase positively influenced stabilization of not only structure but also functioning of chloroplast membranes, thus preventing a transfer of electrons from the ETR to oxygen and subsequent ROS generation at hypothermia. This was confirmed by the analysis of the rate of superoxide anion generation in tested genotypes.