Populus Tomentosa Mitochondria Or Cytosolic Ascorbate Peroxidase Gene Transgenic Tobacco Plants Enhance Tolerance To Abiotic Stress

Reactive oxygen species (ROS) play a key role in plants and are regulated by several ROS-scavenging enzymes. Ascorbate peroxidase (APX), which catalyzes the reduction of hydrogen peroxide, a vital part of ROS, to water, plays a significant role in higher plants. In this study, comparing to wild-type plants, over-expressed Populus tomentosa mitochondria and cytosolic ascorbate peroxidase gene transgenic tobacco plants had no significant difference in morphology under normal conditions. And the over-expressed Populus tomentosa mitochondria ascorbate peroxidase gene transgenic tobacco plants displayed improved resistance with the15%higher relative water content and1.6times of chlorophyll content than wild plants, and the malondialdehyde content of transgenic plants was only55.1%of wild plants during drought, salt or oxidative stresses. Moreover, lower H2O2content,11.3%more ASA consumption,1.18times of the ratio of NADP to NADPH and1.77times of APX activity in the transgenic plants suggested increased ability to eliminate reactive oxygen species. The data of over-expressed Populus tomentosa cytosolic ascorbate peroxidase gene transgenic tobacco plants showed the10.4%higher relative water content and1.53times of chlorophyll content than wild plants, and the malondialdehyde content of transgenic plants was only72.9%of wild plants during drought, salt or oxidative stresses. Moreover,53%more the ratio of NADP to NADPH,23%more ASA consumption,1.85times of APX activity in the transgenic plants suggested increased ability to eliminate reactive oxygen species.Comparing to wild Arabidopsis thaliana, absent APX Arabidopsis mutants present low germination rate and seed rate under noemal conditions that indicated APX acts a crucial role of abiotic stress tolerance in plants.