Advancements in gene suppression | RNAi could be alternative to chemical pesticides
Monsanto’s chief technology officer hinted in a quarterly earnings call with financial analysts in January that the company might be onto something big.
After running through routine updates on corn breeding, soybean yield improvements and other projects, Rob Fraley’s enthusiasm spiked when he began talking about Monsanto’s research and development work on RNA interference (RNAi) for pest management.
“These (tools) can precisely target pests and can result in many of the same benefits we’ve seen with biotechnology traits,” he said.
“So while it’s still in early stages, I have to emphasize that for me this is a really exciting advance, and it reminds of when I first saw the Roundup Ready technology in the late 1980s.”
RNAi could prove to be an alternative to chemical pesticides in insect and disease control.
Monsanto’s website describes RNA interference as a process to turn down or shut off the expression of certain genes, which suppresses the production of a specific protein in an organism. In the case of crop pests, RNAi could potentially shut down proteins related to metabolism or reproduction, thus killing or disabling target insects.
“We can actually feed these RNA molecules to insects, and they will just ingest them. It will get into the cell and do its job,” said Eric Jan, associate professor of biochemistry and molecular biology at the University of British Columbia, where he is part of a team using RNAi to treat viruses that affect bees.
Monsanto and Syngenta have committed large sums of money to RNAi technology over the last 12 months.
Syngenta bought Devgen, a Belgian rice breeding company and a world leader in RNAi crop protection, for $523 million last fall, while Monsanto paid $29.2 million last year for exclusive rights to use the intellectual property of Alnylam Pharmaceuticals, a major player in the RNAi industry.
This year, Monsanto spent $35 million to acquire Rosetta Green, an Israeli company that improves plant traits with RNA interference.
“I think it’s very apparent to these companies … that this is a powerful technology, so investing early and getting a foothold in it (is essential),” said Doug Macron, who reports on gene silencing technology for GenomeWeb, an information service for scientists and tech professionals.
“These companies know the science and they’re careful with their money. There’s a reason why they are spending millions of dollars.”
Since the discovery of RNA interference in the late 1990s, biologists have primarily focused on gene silencing in humans and potential therapeutic treatments for diseases such as diabetes and cancer.
Yet, applying RNAi to human health has proved difficult.
“Delivery (of double stranded RNA) has been the biggest hurdle facing the human therapeutic side. Just getting these things into cells and functioning … is terribly complicated,” Macron said.
“When you’re dealing with insects and plants, that delivery hurdle is significantly lower. In certain types of insects, they can just eat the stuff.”
RNA interference is alluring because it can be tailored to a specific pest, unlike pesticides that kill harmful and beneficial insects alike.
Monsanto is expending a fair portion of its resources on RNAi applications for the western corn rootworm, which is slowly developing resistance to the B.t. corn trait.
The company is also working on topical sprays to deliver RNA that impairs the metabolic functions of target insects.
The company hopes to use the technology to protect crops from viruses and disease as well as insects.
Monsanto declined an interview request for this story because a spokesperson said it’s too early to discuss the technology. It is still in the discovery phase, which is the earliest stage of Monsanto’s research and development work.
Commercialization of the technology may be five to 10 years away, but critics are already lining up to condemn RNAi as dangerous.
Greenpeace questions the safety of RNAi, suggesting it could suppress gene expression in other species, including humans.
Defenders of the technology acknowledge that humans share genetic sequences with insects, but it should be possible to target certain genes in the target pest without risking human health.
“One of the big hurdles is, ‘what effect would this have on other organisms? What effect would that have on humans?’” said Marcé Lorenzen, an entomology professor at North Carolina State University who is studying the potential of RNAi to control the red flour beetle.
“We don’t really expect off-target effects, but you have to go through all the (precautionary) steps.”