AI-Designed Protein Herbicides Target Resistant Weeds
25 September 2026, Wisconsin, USA: Jefferson, Wisconsin, USA agricultural biotechnology startup Quercus Biosolutions has closed an oversubscribed $5 million seed funding round to advance a new class of herbicides built from artificial intelligence (AI) designed proteins rather than the small chemical molecules used in most weed killers on the market today. The company announced the raise on July 29, 2026, with Champaign, Illinois based Serra Ventures leading the round and eight other investors participating, including two funds tied to state corn checkoff programs, the Iowa Corn Opportunities Fund and Kentucky Corn Plus, alongside Starshot Capital, the Grantham Foundation for the Protection of the Environment, Flyover Capital, Rootstock Capital, AgriCap Fund and Ag Startup Engine.
Quercus was founded in 2024 by Jonathan Lightner, a plant scientist who serves as chief executive, and Matthew Crisp, the company’s executive chair, who previously led the gene edited soybean company Benson Hill. The pair set out to build herbicides around proteins instead of conventional agrochemical chemistry, arguing that weeds have evolved resistance to most of the small molecule herbicide classes farmers currently rely on, while very few genuinely new modes of action, meaning new ways of killing a weed at the biochemical level, have reached commercial farms in recent decades.
How the platform works
To design its herbicide candidates, Quercus uses artificial intelligence tools developed with its technology partner Ordaos Bio to model short “mini proteins,” also called peptides, that bind tightly to specific proteins inside target weeds. Conventional herbicides work by using a small chemical molecule to block an enzyme a plant needs to grow, for instance by interrupting photosynthesis or amino acid production. Quercus’s proteins aim at similar kinds of biological targets, but bind through protein to protein interactions rather than small molecule chemistry. Because the shape and binding mechanism differ fundamentally from existing chemical herbicides, the company argues its candidates may be able to kill weeds that have already evolved resistance to today’s products, since the genetic mutations that block a small molecule’s chemical binding site would not necessarily block a differently shaped protein binder.
Manufacturing is another point of difference. Rather than synthesizing chemicals in a reactor, Quercus produces its protein herbicides through precision fermentation, using microorganisms such as the bacterium Escherichia coli or the yeast Pichia pastoris that are engineered to secrete the target protein directly into the fermentation broth. That secretion step matters commercially because it removes the need to break open cells to extract the protein, a costly and technically demanding step in many biologic manufacturing processes, which the company says should help keep production costs closer to those of conventional agrochemicals than typical protein based biologics.
The company currently has five active herbicide development programs, with multiple candidates already in field trials following earlier greenhouse validation work, and says it is beginning the regulatory groundwork needed to bring a first product to market. Quercus has not disclosed a commercial launch date. Beyond herbicides, the company says its AI protein design approach could eventually be extended to fungicides and insecticides, though those applications remain exploratory.
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