USDA, KEITH WELLERGenome-editing technologies—including zinc finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and CRISPR/Cas tools—have facilitated various gene modifications even in higher organisms. Meanwhile, advanced genetic engineering raises a worldwide regulatory issue by creating indistinct boundaries in genetically modified organism (GMO) regulations because, without introducing new genetic material, genome editing can be used to make modifications similar to naturally occurring mutations. To encourage public discussion on the regulatory issue, my colleagues and I last year presented a general drawing of the complicated regulatory issue in Trends in Biotechnology. Now, in an article published in Trends in Plant Science this week (February 25), Motoko Araki and I focus on genome-edited crops in the context of global GMO regulation.
First, we analyzed 13 research articles of genetically modified varieties of barley, rice, sweet orange, wheat, soybean, corn, and tomato. We found that rice was the most frequently modified of all major crops. The most common modification types of all crops studied were mutations with a few bases deleted or inserted (indels), resulting in modified crops that resemble naturally occurring mutants. The genes targeted for mutation had been selected for the purposes such as introducing herbicide resistance, increasing nutritional value, and changing flavor. Although gene modification efficiency varies between target genes, in some cases, it can reach up to 40 percent. Genome editing may induce off-target mutations in plant genomes, which might be associated with health and environmental risks. However, less than half of the ...
