Transgene-product expression levels in genetically engineered breeding stacks are equivalent to those of the single events

Abstract

Transgene product expression levels are measured in genetically engineered (GE) crops containing single transformation events and the measured expression levels are then utilized in food, feed, and environmental safety assessments as part of the requirements for deregulation of the event. Many countries also require measurement of expression levels and safety assessments for GE breeding stacks, even though the breeding stacks are composed of single events that have been previously assessed. Transgene product expression levels were measured in tissues of maize, soybean, and cotton breeding stacks and each of their component single events. Expression levels in the breeding stacks were plotted against expression levels in the single events to quantify the ability of the single events to predict transgene product expression levels in the breeding stacks. These results indicate that transgene product expression levels in single events are a reliable indicator of expression levels in breeding stacks. Based on these results it is concluded that safety assessments for breeding stacks can be conducted using transgene product expression levels from single events.

Cross-crop resistance of Spodoptera frugiperda selected on Bt maize to genetically-modified soybean expressing Cry1Ac and Cry1F proteins in Brazil

“…Measurements of Bt protein expression can vary across environments and be influenced by multiple factors, such as growth stage, position within the plant canopy, and type of plant tissue. The amount of Cry1Ac and Cry1F protein expressed in this soybean technology was reported in the USDA petition for nonregulated status 38 and by De Cerqueira et al 39 . Therefore, the high survival of resistant strains on Cry1Ac/Cry1F-soybean can be explained by the crossresistance between Cry1 proteins expressed in Bt plants [34][35][36][37] and their low natural susceptibility to Cry1Ac protein as reported in studies with Cry1Ac-cotton 32,[40][41][42] , Cry1Ac-soybean 43,44 , and diet bioassays containing Cry1Ac 43,45 .…”