F Budeguer1, R Enrique1, F García Degano2, DB Rodriguez2, M Mocoroa2, D Hernandez2, G Gastaminza2, S Ostengo2, AS Noguera1, MF Perera1 and J Racedo1
1Instituto de Tecnología Agroindustrial del Noroeste Argentino (ITANOA), Estación Experimental Agroindustrial Obispo Colombres (EEAOC) – Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Las Talitas, Tucumán, Argentina; florbudeguer88@gmail.com
2Estación Experimental Agroindustrial Obispo Colombres (EEAOC), Las Talitas, Tucumán, Argentinal
The sugarcane borer Diatraea saccharalis is a major pest of sugarcane (Saccharum hybrids) in the Americas. The insect is partially controlled by cultural, biological, and chemical methods, but still causes significant economic losses. Genetic transformation of sugarcane with genes from Bacillus thuringiensis (Bt) constitutes an efficient technology to address borer management. In sugarcane, the expression of individual Bt proteins has been previously reported, but not the stacking overexpression of Cry and vegetative insecticidal proteins (Vip). In the present study, cry and vip genes were incorporated by microprojectile bombardment into embryogenic sugarcane calli of the variety TUC 03-12. The presence of the transgenes was evaluated by PCR assays. Subsequently, transgenic lines were acclimated and multiplied in the greenhouse for phenotypic and molecular assessments. Lateral flow detection kits were used to determine the presence of Cry and Vip proteins. The resistance of transgenic sugarcane lines against D. saccharalis was evaluated through bioassays under controlled conditions. The expression levels of transcripts in candidate lines were quantified by qRT-PCR assays. Out of 374 lines evaluated by PCR, 229 were positive for at least one of the transgenes. The presence of the Cry protein was detected in 123 transgenic lines evaluated, whilst the Vip protein was detected in three lines. Among 134 lines evaluated in bioassays, 31 lines showed high toxicity levels to D. saccharalis larvae (>90% mortality) and 29 lines revealed toxicity levels causing 67-89% mortality. Of these phenotypically assayed lines, 19 relative gene expression levels were studied, showing variations between 3 to 140-fold for the cry gene and between 2 to 1400-fold for the vip gene compared with non-transformed control plants. Insect resistance was significantly improved by the genetic transformation of sugarcane with cry and vip genes. Developing resistant transgenic varieties will provide a technological solution that could be included into integrated pest management.