Effect of the overexpression of external alternative NADH dehydrogenase gene in Arabidopsis on the resistance of transformed tobacco plants to negative temperatures

The study aims to confirm the functional activity and localization of the At_NDB2 transgenic protein of Arabidopsis in tobacco cells and to evaluate the effect produced by the permanent expression of external alternative NADH dehydrogenase on the resistance of a heat-loving plant to low temperatures. Proteins and mitochondria were isolated from the leaves of tobacco plants grown at 25 °С (day/night) at the 7-leaf stage. At_NDB2 protein localization in mitochondria was determined via electrophoresis and immunoblotting. The functional activity of At_NDB2 was confirmed through the polarography of isolated mitochondria and the specific mitochondrial complex I inhibitor (rotenone). It was also found that the cyanide-resistant respiration rate and the activity of an alternative oxidase enzyme were significantly higher in transgenic plants than in wild-type plants. In order to determine the resistance to low temperatures, the parent and transgenic tobacco plants were grown in soil until the 2–3 and 6–7 leaf stages, after which they were kept at 3 to -3 °С for a day in the dark and left to regrow at 25 °С for seven days. Although it was previously shown that oxidative stress is reduced in transgenic plants at low temperatures as compared to wild-type plants, it was established that the tolerance of transgenic and nontransformed plants does not differ. Thus, alternative NADH dehydrogenase activity was found to reduce oxidative stress and increase alternative oxidase activity, without enhancing the resistance of Nicotiana tabacum to negative temperatures.