EVALUATION OF THE TOXICITY OF THE Cry2Aa AND Cry2Ab RECOMBINANT PROTEINS AGAINST Tecia solanivora (Lepidoptera: Gelechiidae)

Abstract

Potatoes can be attacked by several pests such as Tecia solanivora. The cry genes of Bacillus thuringiensis have been used to generate transgenic plants. The objective of this study was to determine the toxicity of the Cry2Aa and Cry2Ab recombinant proteins against larvae of T. solanivora. By PCR, the cry2Aa and cry2Ab genes were amplified using DNA from B. thuringiensis subsp. kurstaki HD-1. Each amplified product was ligated into the pET151/D-TOPO® vector, and subsequently transformed and expressed in Escherichia coli strains BL21. The recombinant clones were confirmed by PCR, restriction enzyme cutting and sequencing analysis. Recombinant proteins were detected by 8% SDS PAGE gels and immunodetection strips. For bioassays, three replicates of Parda Pastusa potato cultivar were nebulized with E. coli BL21-Cry2Aa or E. coli BL1-Cry2Ab recombinant strains and then infected with T. solanivora larvae, reaching levels of efficacy of 71.3 and 36.8 %, respectively. Biostat® 2007 was used to determine lethal concentrations, obtaining LC50 values of 167.7 and 554.6 ?g/ml for BL21 Cry2Aa and Cry2Ab, respectively. The results allow concluding that the Cry2Aa protein can be a promising alternative for the biological control of Teciasolanivora .