Biosafety Risk of Genetically Modified Crops Containing Cry Genes

Abstract

Genomic technologies started in the early 1980s to improve the genomes of cultivated crop species. For example the term “Bt” comes from the soil bacterium Bacillus thuringiensis containing genes, e.g. Cry1Ac, Cry2Ab, Cry1F, Cry3Bb1, that provides protection against lepidopteran insect pests. Those genes have been inserted in crops such as corn, cotton, soybean, rice, potato and canola released for cultivation in mid 1990s in USA, and later in many other countries like China and India. About 29 countries commercialized genetically-modified (GM) or ‘transgenic’ crops while 30 countries granted regulatory approvals for planting GM-crops; together making 75 % of the world population. Potential harmful effects of the Bt-crops on non-targets were quantified before releasing such non-conventional crops into the environment. The cultivation of Bt-crops were most commonly found safe, based on various studies including the insertional impact of transgene and its regulatory elements on plant phenotype and agronomic performance, effect on non-target organisms (NTOs) and nutritional impacts on multiple experimental models. Albeit the studies were conducted for limited durations. However, the skeptics always claim for conducting extensive clinical as well as field trials, and also doubt on methods and procedures of calculating the ecological risks. This debate is still on-going, especially after reports on substantial reduction of monarch butterfly caterpillars exposed to Bt-maize pollen, though later nullified; and detection of traces of transgene in various tissues of experimental animals. Procedures, methods and protocols for evaluating potential risks of GM-crops and foods should be standardized as the first step to build trust of researchers and end-users. Many efforts should be exerted in deploying genes of interest, marker genes and regulatory sequences invoking no or little issues of potential risks to the ecosystem.