| Genetic engineering of insect-resistance provides a new way to breed new variety of forest tree for insect-resistance. Compared with traditional breeding, it can short tree breeding periods greatly, and possesses some advantages, such as creating new genetic property of forest tree specially, reducing investment and environmental contamination. In this study, hybrid aspen (Populus tremulaxP. tremuloides) was selected as target material for genetic transformation by Agrobacterium. Some factors that affected the efficiency of genetic transformation were studied. Stable integration of the chimeric gene (Spider insecticidal peptide and Bt) in the plant genome was confirmed by GUS detection and PCR-Southern blot analysis. The main results are as follows:1. The appropriate concentration of kanamycin for selection culture was determined. The differentiation of leaf explants was inhibted on WPM medium containing 20mg/L kanamycin; All shoots that were transferred to rooting medium containing 15mg/L kanamycin were inhibited completely to root.2. The effect of cefotaxime in different concentrations was evaluated on the leaf explants of the hybrid and Agrobacterium tumefaciens LBA4404. A. tumefaciens LBA4404 cultured on solid LB medium containing 600mg/L cefotaxime and 50mg/L kanamycin was killed, and hybrid aspen was more resistant to cefotaxime.3. Some factors that affected the genetic transformation were assessed. The procedure was established.4. 2 transformed hybrid buds out of 97 explants were obtained from cocultivation of the leaf explants with Agrobacterium .5. The shoots that survived by kanamycin selection were tested randomly by GUS expression. 21 (or 84.0%) ones in 25 plants were GUS positive.6. 82.4% of transgenic regenerated plants survived on rooting medium containing 15mg/L kanamycin7. PCR-Southern blot analysis was carried out on transgenic plants in GUS positive to confirm stable integration of the exogenous gene in the plant genomes.
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