The Analysis Of Drought And Salt Tolerance Of Transgenic Tobacco With Overexpression AER/DHAR And AER-DHAR Gene

There will be a substantial accumulation of ROS in plants under adversity stress. On the one hand, ROS can damage to cells by modifying DNA, RNA, proteins and carbohydrates. On the other hand, a large number of reactive oxygen species can cause a chain reaction of lipid peroxidation, then produce large amounts of aldehydes. Aldehyde is the product of downstream of ROS. It has more harmful than the ROS substances. It can destroy the integrity of the membrane and cause poison to cells. So the oxidative damage can be divided into upstream of the active oxygen damage and downstream of the active aldehyde group. 2-olefine aldehyde are more toxic which contains α,β-unsaturated double bond in the downstream. 2-alkenal reductase can catalytic hydrogenation of unsaturated double bond of olefin aldehyde to generate saturated aldehydes, then generates carbon dioxide and water by other aldehyde reductase, then greatly reduced the toxicity of formaldehyde.In this study, we investigated whether can use 2- olefine aldehyde reductase(AER)to clear the aldehyde in downstream of oxidation damage to improve drought resistance and salt resistance of tobacco, and verify whether clear the upstream and downstream of oxidative damage at the same time can improve the drought resistance and salt resistance of plants preferably. Transgenic tobacco plants with overexpressing 2-alkenal reductase, overexpressing dehydroascorbate reductase, wild-type tobacco plants( SR) and vector-transformed control line(VECT)were used to measure the biomass, photosynthetic rate, chlorophyll fluorescence parameters, contents of chlorophyll, MDA, H2O2 and Na+ under drought stress, rehydration and salt stress. We got these results as following:(1)The results showed that the biomass, contents of chlorophyll, photosynthetic rate, chlorophyll fluorescence parameters and the capability for scavenging H2O2 of the transgenic tobacco plants were significantly higher than wild-type tobacco plants and vector-transformed control line under drought treatment. After rehydration, the physiological indexes of tobacco recovered. The recovery capability of transgenic lines is better than that of wild-type and vector-transformed control line. It turned out that the transgenic tobacco plants with overexpression AER, DHAR and AER- DHAR by increasing antioxidant capacity to improve drought resistance ability of plants.(2)The overall growth situation and photosynthetic rate of transgenic tobacco are significantly better than the wild-type under salt stress. Meanwhile, the aboveground biomass, chlorophyll content and photosynthetic rate were all markedly higher than wild-type plants and vector-transformed control line. However, the content of MDA and H2O2 of transgenic plants were obviously lower than wild-type plants. In addition, the content of Na+ of transgenic plants were observably lower wild-type plants and vector-transformed control line. The results showed that over-expression AER, DHAR and AER- DHAR were significantly improve the salt resistance of tobacco.( 3) We obtained that eliminating the downstream(over-expression AER) and upstream(over-expression DHAR) of oxidative damage can prominently enhance the drought resistance and salt resistance of plants. The drought resistance and salt resistance of overexpression of AER-DHAR gene of tobacco is not better than single gene AER/DHAR of transgenic tobacco plants.From the above results, we can obtain that overexpression of AER and DHAR gene could enhance drought and salt tolerance in transgenic tobacco plants by eliminating the aldehyde in downstream of oxidation damage. We comprehend the role of AER in the antioxidant system. Further more, we can understand the role of antioxidant system in improving the drought resistance and salt resistance of plants.