Molecular Identification And Analysis Of Salt Tolerance On The Populus Tomentosa With AhDREB1 Gene

Populus tomentosa has been highly valued and considered as the best tree species with fast growth and high wood quality among native poplar species in China (Zhu et al. 1997). But the distribution of Populus tomentosa was confined by its limitation of salt-resistance and parts of plants can't grow normally when the concentrations of salt attain to 3‰ in the soil. Recent progress in biotechnology has made it possible to breed new clones with improved resistance to salt by genetic engineering. In this study nine fine transgenic individuals with Km resistance and non-transformed plant (control plant) were chosen. The regulatory pathway of the AhDREB1gene in plant genomes of transgenic Populus tomentosa was confirmed by means of Southern blotting and salt tolerance analysis .These results were reported in this paper. The results showed that:(1) Southern blotting analysis showed that AhDREB1 had integrated into genome of transgenic individuals labeled T12,T46,L26,L63,L73. Genomic DNA of AhDREB1 was digested with DraI only, so one or two copies were in genome. Although L83, L113,L150,L163 were transgenic individuals with Km resistance, there were no blotting band. Therefore, they were false positive individuals. The control plant also had no blotting signal. All the AhDREB1- positive individuals had one 800 bp band, whether this phenomenon did indicate AhDREB1 had integration hot spot in Populus tomentosa genome also to be further proved.(2) All plants in the pot experiment were determined. When the NaCl concentration increased to 3.06‰, the difference was appeared between transgenic individuals and the control plant. The survival rate of transgenic individuals still was 100%, but the survival rate of the control plant declined to 40%. When the NaCl concentration increased to 5.48‰, the difference was very remarkable, the growth of transgenic individuals was restrained, the survival rate was 84.4%, and control plant had died actually.(3) Physiological biochemistry indexes of individuals with NaCl treatment were determined. Chlorophyll content, proline content, peroxidase(POD) activity, and superoxide dismutase (SOD)activity of transgenic individuals were higher than the control plant , it is indicated that transgenic individuals were affected by salt stress more slimly. Malonaldehyde(MDA)content of transgenic individuals was lower than the control plant, it is indicated that transgenic individuals adapted to salt stress environment better. Therefore, Populus tomentosa with AhDREB1 had more obvious advantages and better tolerance than the control plant.