TRANSGENIC TOBACCO PLANES WITH EFFICIENT INSECT RESISTANCE

Insecticidal protein gene CryIA(c) from Bacillus thuringiensis HD-1 (B. t. toxin gene) with 5'-end modified and 8'-end deleted to 4 different lengths were inserted downstream of 35S promoter with double enhancer and ''Omega''' fragment of TMV-RNA cDNA in the binary vector pBin438 to construct the chimeric expression vector of B. t. toxin gene. Leave stripes of tobacco plant var. NC89 widely grown in China were transformed with A. tumefaciens LBA4404 harbouring the above expression vectors respectively, and kanamycin resistant tobacco plants were regenerated. Insect test with tobacco budworm H. assulta showed that insect-resistant transformants could be obtained from the regenerated plants transformed with B. t. genes of different lengths though highest percentage (similar to 50%) of plants with a high motality (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 resistance showed that B. t. toxin gene and the character of insect resistance have been inherited in the progenies. Insect-resistant homozygotes D8-14 and D19-8 have been selected for small-scale field tests.