Transgenic Tobacco Plants With Efficient Insect Resistance

Insecticidal protein gene CryIA(c)from Bacillus thuringiensis HD-1(B.t.toxin gene)with 5’-end modified and 3’-end deleted to 4 different lengths were inserted downstream of 35S promoterwith double enhancer and"Ω’"fragment of TMV-RNA cDNA in the binary vector pBin438 to constructthe chimeric expression vector of B.t.toxin gene.Leave stripes of tobacco plant var.NC89 widelygrown in China were transformed with A.tumefaciens LBA4404 harbouring the above expression vectorsrespectively,and kanamycin resistant tobacco plants were regenerated.Insect test with tobacco budwormH.assulta showed that insect-resistant transform.ants could be obtained from the regenerated plantstransformed with B.t.genes of different lengths though highest percentage(～50%)of plants with ahigh morality(90%-100%)to the testing insects is among those transformed with 1.8-kb toxin gene.Genetic,molecular and biological analyses of T1 and T2 progenies of plants with high efficient insect re-sistance showed that B.t.toxin gene and the character of insect resistance have been inherited in the pro-genies.Insect-resistant homozygotes D8-14 and D19-8 have been selected for small-scale field tests.