Future challenges feeding transgenic plants

Since humans made the transition from hunter-gatherers to agriculture, crops have been subject to anthropogenic selection in an effort to improve agronomic traits and nutritional quality. For almost 80 yr, diversity in agricultural crops has been promoted through indirect genetic mutation induced by exposure to radioactivity and/or chemicals. According to the FAO/ IAEA, more than 3,000 plant mutants are registered; with more than 2,000 modified plants being used for food and feed production, of which 1,400 are major staples (Ahloowalia et al., 2004; Kharkwal and Shu, 2009). In the last three decades, advances in molecular biology have made targetoriented gene transfer across the species barrier possible. The majority of first-generation commercialized genetically modified (GM) crops have been engineered for enhanced agronomic performance through transformation with genes encoding either herbicide tolerance, pest resistance, or both (Flachowsky and Aulrich, 2001). The cultivation of GM crops has become the subject of global controversy over their safety, trade, regulation, and implications for the environment throughout all sectors of society. In 1996, the first GM crops serving as major feedstuffs for livestock entered the North American market. These included herbicide-tolerant soybeans and canola and pest-protected corn. From 1996 to 2015, the cultivated area of GM crops increased more than 100-fold to 180 million ha globally (James, 2015). Regulations concerning GM plants were established by major international organizations prior to their commercialization, including the policy of substantial equivalence, which was first introduced by the Organization for Economic Cooperation and Development (OECD, 1993) and was adopted by both the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) as the most appropriate regulatory framework (FAO/WHO, 2000). Substantial equivalence was based on comparison of GM plants to an appropriate conventional counterpart from which the GM line was derived. Once defined plant traits had been deemed equivalent between the two lines, the novel transgenic trait became the focus of the safety assessment. With the 20-yr anniversary, detailed information about commercial cultivation, the feeding qualities of GM crops for livestock, and their nutritional evaluation have been reviewed previously by academia (e.g., Flachowsky, 2013; van Eenennaam and Young, 2014; Nicolia et al., 2014; Smyth et al., 2015; Flachowsky and Meyer, 2015; Harvie, 2015; Watson and Preedy, 2015; Brookes and Barfoot 2015, 2016; Panchin and Tuzhikow, 2016; Qaim 2016) and scientific bodies (e.g., JRC, 2016; NASEM, 2016; The Royal Society, 2016) analyzing socio-economic effects of cultivation, related environmental aspects, and the impact on human and animal health.