[Studies on transgenic tobacco plants expressing two kinds of insect resistant genes]

A synthetic Bt cry1Ac gene fussed with a secretary signal coding sequences at 5' end and a modified gna gene were used to construct a plant expression vector pBSGS1M+ and this vector was transferred into tobacco (Nicotiana tabacum L.) by Agrobacterium-mediated transformation method. Results of PCR, Southern blot and Slot blot analysis indicated that both the chimeric Bt cry1Ac and gna genes were integrated into the genomes of transformed plants. Western blot analysis indicated that at least the cry1Ac protein was produced in transgenic plants. Upon insect bioassay using cotton bollworm (Heliothis armigera Hubner), the mortality of insect larvae on 60% regenerated plants reached 100% in 5 days post infestation and the growth of the survived larvae was seriously inhibited; The results from insect bioassay with peach aphid (Myzus persicae) showed that the transgenic plants were aphid-resistant, evidenced by a 50%-60% reduction in aphid population density, even over 80% for some individual transgenic plants. These results reflect that the modification of the two insect resistant genes and construction of the expression vector are correct and could be valuable for later application in crop breeding for insect resistance.