Ectopic Expression of the Leptochloa fusca and Allium cepa Lectin Genes in Tobacco Plant for Resistance against Mealybug ( Phenococcus solenopsis )

Insecticidal toxicity of the Allium cepa and Leptochloa fusca lectin genes was tested against sucking insect pest mealybug (Phenococcus solenopsis). Both genes were cloned under 2XCaMV35S promoter and transformed into tobacco plants using Agrobacterium mediated plant transformation method. Integration of the lectin genes was confirmed by southern hybridization and expression of the transgene was confirmed by real time PCR. Leaves of the transgenic plant were used for insect bioassays under laboratory and glasshouse conditions. In the case of laboratory experiment, the mealybugs could not survive or multiply on leaves detached from both types of the transgenic tobacco plants. The insect mortalities 87.50% and 90% were observed on the transformed and non-transformed plants respectively. Similarly, in the case of greenhouse experiment, 81.25% and 87.5% insect mortalities were recorded when nymphs of the mealybugs were released to feed on the alive transgenic and non-transgenic tobacco plants. These results suggest that lectin genes can be effectively transformed in the major for the control of mealybugs.