Expression of multiple insecticidal genes confers broad resistance againsta range of different rice pests

We report the simultaneous introduction of three insecticidal genes (the Bt gene cry1Ac and cry2A, and the snowdrop lectin gene gna) into commercially important indica rice varieties M7 and Basmati 370, by particle bombardmen t. Transgenic plants expressed Cry1Ac, Cry2A and GNA at different levels, e ither singly or in combination at 0.03-1%, 0.01-0.5% and 0.01-2.5% of total soluble protein, respectively. The transgenes showed stable transmission a nd expression, and R-1 transgenic plants provided significant (p<0.01) prot ection against three of the most important insect pests of rice; rice leaf folder (Cnaphalocrocis medinalis), yellow stemborer (Scirpophaga incertulas ) and brown planthopper (Nilaparvata lugens). The triple transformants show ed significantly (p<0.05) higher resistance to these insects than plants ex pressing single transgenes. Bioassays using the triple-transgenic plants sh owed 100% eradication of the rice leaf folder and yellow stem borer, and 25 % reduction in the survival of the brown planthopper. The greatest reductio n in insect survival, and the greatest reduction in plant damage, occurred in plants expressing all three transgenes. This approach maximises the util ity of gene transfer technology to introduce combinations of genes whose pr oducts disrupt different biochemical or physiological processes in the same insect, providing a multi-mechanism defence.