THE POTENTIAL OF CROSS RESISTANCE BETWEEN MONO TRAIT AND STACKED GENE TRANSGENIC EVENTS - A CASE STUDY

Abstract

The first-generation transgenic cotton (Gossypium hirsutum L.), Bollgard, which contains a single toxin protein gene cry1Ac from Bacillus thuringiensis var. kurstaki Berliner, was approved by the National Biosafety Committee (NBC) for commercial growing in Pakistan in 2011 and the yield enhancement is promising, with an increase in cotton bales up to 150 million- the record productivity of the cotton sector. However, the planting of illegal Bt cotton varieties in farmers fields could be traced as back as in 2003. The wide spread cultivation of these mixed character (varying expression of Bt toxin) varieties has threatened the potential evolution of resistance in target insects. After two years of field trials for agronomic and ecological assessment, the commercialization of another GM event, MON89034xNK603 is imminent. The purpose is to provide an effective control of lepidopteran insect pests in maize crop to reduce a reliance on chemical pest control as well as a flexible, environment friendly utilization of glyphosate based weedicides. This review presents a situation analysis for the need of this technology in Pakistan. Aspects regarding the previous adoption of GM cotton are discussed to pre-determine the prospects and potential risk of cross resistance between MON531 and MON 89034. It is necessary because partial control of lepidopteran insects especially Helicoverpa spp. (Helicoverpa armigera, Helicoverpa zea), Pectinophora gossypiella, Spodoptera littoralis, Spodoptera exigua, Earias vittella, Earias insulana without structured refuges for the Bt crop provides a basis for an increase in frequency of resistant alleles.