© ISTOCK.COM/TAWNINTAEWRNA interference (RNAi)—the process by which small interfering RNAs (siRNAs) bind to and cleave complementary mRNA sequences, inhibiting their translation into proteins—is not new to agriculture. In fact, as a naturally occurring biological process, RNAi was mediating plant metabolism, growth, and pathogen defense long before humans began cultivating crops for their own benefit. But in the last 15 years, RNAi’s role in agriculture has grown as researchers have developed greater understanding of the mechanisms underlying the phenomenon and employed it to improve pathogen resistance, nutrition, and yield of crop plants. RNAi-enhanced crops have been approved for cultivation by regulatory agencies in the United States, Europe, Canada, Australia, New Zealand, and Brazil, and some of these crops—for example, papaya—have already reached our plates.
RNAi is a particularly potent tool for fighting common crop pathogens. By simply integrating virus- or bacteria-derived DNA sequences into the plant genome, pathogen-targeting siRNAs can be produced, triggering the endogenous RNAi mechanisms to target and degrade homologous sequences produced by invading pathogens. Commercial cultivation of virus-resistant papaya and extensive field testing of virus-resistant plum (under high disease pressure) since 1996 have shown that the pathogen-derived RNAi technology can deliver very effective and durable resistance. More recently, this strategy has produced virus-resistant common beans, fungal-resistant bananas, nematode-resistant soybeans, and insect-resistant corn. To date, RNAi has proven more cost-effective and environmentally friendly than the use of pesticides to control pathogens, and RNAi-fortified crops have the potential to impact food security and economic development. Recent regulatory approval ...
