Abstract
Genetically modified crops have been grown commercially for more than two decades. Some of these crops have been modified with genetic constructs that induce gene silencing through RNA interference (RNAi). The targets for this silencing action are genes, either specific endogenous ones of the host plant or those of particular pests or pathogens infesting these plants. Recently emerging new genetic tools enable precise DNA edits with the same silencing effect and have also increased our knowledge and insights into the mechanisms of RNAi. For the assessment of the safety of foodstuffs from crops modified with RNAi, internationally harmonized principles for risk assessment of foods derived from genetically modified crops can be followed. Special considerations may apply to the newly expressed silencing RNA molecules, such as their possible uptake by consumers and interference with expression of host genes, which, however, would need to overcome many barriers. Bioinformatics tools aid the prediction of possible interference by a given RNA molecule with the expression of genes with homologous sequences in the host crop and in other organisms, or possible off‐target edits in gene‐edited crops. © 2020 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Highlights
Since the mid-1990s, there has been a rapid adoption and expansion of genetically modified (GM) varieties of major commodity crops by farmers in many parts of the world, accruing to 192 million hectares in 2018.1 A major part of these crops is accounted for by a limited number of crop species in which specific, newly expressed proteins are produced, imparting traits of herbicide tolerance and insect resistance
A surge in commercial applications in food and feed production can be expected in the near future owing to our increased knowledge about RNA interference, the accessibility of tools for directed crop mutagenesis, and the expanding scope of experimental applications
This begs the question if the safety assessment approaches that have been hitherto followed for GM crops are still sufficiently adapted
Summary
Since the mid-1990s, there has been a rapid adoption and expansion of genetically modified (GM) varieties of major commodity crops by farmers in many parts of the world, accruing to 192 million hectares in 2018.1 A major part of these crops is accounted for by a limited number of crop species in which specific, newly expressed proteins are produced, imparting traits of herbicide tolerance and insect resistance. Cry proteins occur naturally in the endosporal crystal inclusions of Bacillus thuringiensis, whilst VIP proteins are formed during the vegetative stages of this bacterium Proteins from both categories are selectively toxic for particular insect species, such as larvae of lepidopterans (moths) and coleopterans (beetles) feeding on these crops. Besides these crops expressing proteins encoded by the introduced genes, repression of protein expression is the target of the genetic modifications in various other commercial and precommercial GM crops. It was known that the introduction of sense and antisense DNA homologues of endogenous genes could bring about this gene silencing, knowledge of the underlying mechanism, called RNA interference (RNAi), has been accruing significantly since. This has led to insights that triggered further advancement of this technology
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