By Janet Kanters

In a groundbreaking stride towards revolutionizing agricultural practices, GreenLight Biosciences, a biotechnology company founded in 2008, has emerged as a trailblazer in RNA research.

Indeed, GreenLight Biosciences’s pioneering RNAi technology represents a significant leap forward in agricultural innovation. With its RNA-based products, GreenLight Bio is revolutionizing the way farmers approach pest and disease management.

RNA, or ribonucleic acid, is a fundamental molecule found in all living organisms, including plants. RNA plays a crucial role in various biological processes, including protein synthesis and regulation.

The discovery of RNA interference (RNAi) by Andrew Fire and Craig Mello in 1998 paved the way for GreenLight Bio’s innovative approach. Mark Singleton, chief commercial officer and general manager at GreenLight, notes that RNAi technology harnesses the natural mechanism of RNA to modulate protein production, offering a targeted and environmentally friendly alternative to traditional pesticides.

GreenLight Bio’s journey wasn’t solely about making RNA. “Our initial mission was to find a better way to make naturally occurring molecules more efficiently,” Singleton explains. “The challenge lay in providing a reliable and cost-efficient energy source for the biological systems involved.”

GreenLight’s solution? Recycling spent yeast, abundant in RNA, to produce RNA-based products.

“What we do is we recycle spent yeast, chop up the RNA it contains into nucleotides, and use a unique energy system to put those nucleotides back together in the order needed for our products,” Singleton elaborates. “It’s a massive recycling program within our manufacturing process.”

So, what can RNA do in plant health? “RNAi technology allows us to stop the natural processes in an organism by preventing the production of specific proteins,” Singleton clarifies. This capability opens doors to myriad applications, from developing highly targeted pesticides to mitigating the effects of plant pathogens like fusarium, which produce mycotoxins harmful to both crops and consumers.

Natural biopesticide first product release
GreenLight Bio’s first product, Calantha, is a bioinsecticide based on RNA, designed to target and control Colorado potato beetle (CPB). The beetle, which decimates plants in the nightshade family, easily develops resistance to pesticides – multiple modes of action are needed to successfully control CPB infestations, especially in areas with multiple generations.

Calantha is mixed with water and sprayed using standard agricultural practice over crops, at less than one-tenth the rate at which many conventional industrial chemicals are normally used on fields.

“We first ventured out into the fields in 2018 in the U.S. for limited replicate trials. And since then, we must have done several hundred trials around t he world, and this is how we figured out that we need 4 g per acre,” equivalent to a spoonful of sugar spread on an American football field. Consumption of the dsRNA causes the Colorado potato beetle to stop eating and expire from its own toxins.

Highly specific to CPB, the company added that Calantha degrades rapidly in soil and water and does not harm honeybees, butterflies and other nontarget insects or mammals. It controls all stages of the life of the beetle but is most effective on young larvae up to one-quarter inch in length.

In addition to biopesticide development, RNA-based solutions have the potential to enhance plant resilience to abiotic stressors, such as heat and water stress, and can mitigate the effects of plant pathogens like fusarium and botrytis.

“One of our products targets fusarium by preventing the fungus from producing mycotoxins, addressing a significant challenge for cereal growers worldwide,” Singleton explains. “But RNA technology goes beyond pesticides. It can boost plant immune responses, improve water and nutrient use efficiency, and manage various stressors like heat stress.”

Regulatory challenges
Calantha is the first GreenLight Bio product to complete U.S. regulatory review and be available for commercial sale. It is also under review by regulators in other key markets around the world.

The company’s journey through the regulatory process has been marked by collaboration and perseverance. Singleton highlights the company’s proactive engagement with regulatory agencies, such as the EPA and OECD, to ensure compliance and build confidence in RNA technology.

“As a trailblazer in RNA technology, we faced the challenge of navigating regulatory frameworks that hadn’t previously considered this technology,” Singleton acknowledges. “Regulators require thorough risk-benefit analyses, and our task is to demonstrate the safety and efficacy of our products.

“They (regulators) were over 48 months into what was then an 18-month process for Calantha, so it didn’t happen really quickly. They spent a lot of time looking at it,” he says. “I would say that the BPPD (Biopesticides and Pollution Prevention Division), which is the group that worked on our submissions, worked diligently and did a great job of looking at the product. Here we hand them a brand-new technology, all while the number of biologicals going through their hands is going up.”

The EPA released a decision document detailing its more than four-year review of Calantha’s safety and efficacy data and information submitted by GreenLight Bio, including its response to submissions received during an extensive public comment period. Calantha is the first registration of a foliar-applied product with an RNA ingredient under Section Three of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). This novel RNA-based approach enables Calantha to target the Colorado potato beetle specifically.

In a separate announcement earlier this year, the Insecticide Resistance Action Committee, a global public-private technical advisory group focused on resistance management, acknowledged this novelty by creating a new category, Group 35, for ledprona, the active ingredient in Calantha, in its Mode of Action classification. Calantha is the first GreenLight Bio product to complete U.S. regulatory review and receive regulatory approval.

Further RNAi research and trials
While regulatory processes are underway in various other countries, GreenLight Bio remains focused on expanding its portfolio. Calantha is “registered in the U.S. and Ukraine, with submissions in progress for the EU and Canada,” Singleton reveals. “We’re also developing products for other agricultural pests and diseases, including fungicides and herbicides.”

One notable achievement is GreenLight’s anti-mite RNA treatment for beehives, addressing the threat posed by the varroa destructor mite. For beekeepers, this invasive, parasitic mite, smaller than a pin head, extracts a big toll from the bees it feeds upon. Varroa mites have plagued beekeepers ever since arriving in the U.S. from Asian honeybees in the mid 1980s, but in recent years, commercially available treatments have lost their efficiency, even as the mite’s viral load increases.

“We have also submitted here in the U.S. for a second product, which is to control varroa mites on honeybees. We’re very excited about the product – it offers tremendous performance at a time when the existing solutions are starting to suffer from resistance,” says Singleton. “We are hoping to hear from the EPA at some point this year. And we are ready to start submissions in other territories around the world for that particular product, including Europe, Australia, New Zealand, Canada, Mexico, U.S. and Turkey, amongst other countries.”

But GreenLight Bio’s research and development doesn’t stop there.

“Our third and fourth products will be fungicidal,” says Singleton. The first will be targeting powdery mildew on grapes, and only grapes at this point. “Powdery mildew affects a lot of species, a lot of plants. But this shows you how specific RNA is – our product is designed to only work on a fungal species that is unique to grapes.”

The company’s fourth product will be a botrytis specialist.

“Following that, we have another acaricide, this one has been designed to be active on two plant-damaging spider mite species, the European red mite and the two-spotted spider mite,” notes Singleton. “That will be the first RNA product that has been designed to work on two species. But only those two species; it doesn’t do any damage to the beneficial spider mites that farmers and growers will release into their crops. So it maintains that ability to be highly selective whilst going after two very relevant spider mites that growers have to deal with.

“And then we have a few other insecticides – thrips is in the early stages of development as well. And we’re also working on using RNA on plant species. So, we have a herbicide product that is in very early stages of development, on horseweed.”

The company is also looking at products that can help regulate the plant’s immune response, such as managing heat stress and mitigating water stress. “That’s an early-stage program as well that we’re looking at – helping the plants with stress and the abiotic stresses they will encounter,” explains Singleton.

“Really, we have a fully fledged portfolio across all of the major indications or categories that a grower will need, and we’re able to do that with our RNA portfolio. This is a technology that I am very excited about because of what it has to offer farmers and growers.”