Safe use of Cry genes in genetically modified crops

Abstract

Genomic technologies have been used to improve cultivated crop species. For example, Bt genes such as Cry1Ac, Cry2Ab, Cry1F and Cry3Bb1 are derived from Bacillus thuringiensis, a soil bacterium. Such genes provide protection against lepidopteran insect pests. Bt genes have been introduced in corn, cotton, soybean, rice, potato and canola. Genetically modified (GM)-cotton, containing the Cry1Ac gene, was released for cultivation in the mid-1990s in the USA and later in 28 countries including China and India. Potential harmful effects of the Bt-crops on non-targets were assessed before release into the environment. Most commonly, cultivation of the Bt-crops was found safe. Safety was tested using various experiments including: the insertional impact of transgene and its regulatory elements on plant phenotype and agronomic performance; effect on non-target organisms; and nutritional impacts on multiple experimental models, albeit the studies were conducted for limited durations. However, skeptics always claim for conducting extensive clinical as well as field trials and also cast doubt on methods and procedures of calculating the ecological risks. This debate got further momentum especially after the publication of reports on substantial reduction in monarch butterfly caterpillars when exposed to Bt-maize pollen—though later nullified—and detection of traces of transgene in various tissues of experimental animals. It is generally accepted that procedures, methods and protocols for evaluating the potential risks of GM-crops and foods should be standardized for building confidence of all stakeholders. 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.