Cloning Of APX Gene From Populus Tomentosa And Expression Analysis

There will be production and accumulation of reactive oxygen species(ROS) in plant cells because of the environmental stress. If ROS can not be scavenged efficiently,the plant cells will be injuried. APX is a protein with heme in it and plays an important role in protecting higher plant cells against the toxic effects of H2O2. APX is also an important enzyme of enzymatic detoxication system in higher plants.In our study,two APX genes were cloned from 741 Populus tomentosa, and then they were respectively integrated into the genome of tobacco. We also analysis the importance of APX genes which enhance the ability of resistance to salt and drought stress in plants. The main research and result of experiment were showed as following:1. We predict two APX genes from Populus trichocarpa by electrical cloning. Then we extract Populus tomentosa RNA and synthesis Populus tomentosa cDNA. Because of the high degree of homology between Populus tomentosa and Populus trichocarpa, the primers of Populus tomentosa were designed and the coding sequences of two APXs from Populus tomentosa were isolated. These two APXs were named APX-I and APX-II.2. The transformation vector APX-I-PBI121 and APX-II-PBI121 were constructed. Two recombined plasmids were transferred into Agrobacterium tumefacien LBA4404, and be transferred into tobacco. After a period of culturing and selecting, some transgenic plantlets resistant to kanamycin were obtained from leaf discs by MS medium with kanamycin pressure. Some tobacco plantlets transferred APX-I gene and APX-II gene were obtained by detection of PCR and Southern Hybrid.3. Transgenic tobacco plants were treated with salt stress and drought stress. Our study shows: Compared with non-transgenic tobacco, transgenic tobacco has better ability of regulating APXs activity and tolerating salt and drought stress. So ascorbate peroxidase plays an important role in enhancing tolerance of transgenic tobacco plants to salt and drought stress.