It might sound like science fiction, but bioengineers want to bypass photosynthesis and grow crops in tall, dark towers surrounded by solar panels. They estimate that their new strategy for “electro-agriculture” could reduce the land needed for food production by 88%.
For hundreds of millions of years, plants have used photosynthesis to capture energy from sunlight and store it as chemical energy. The reaction converts water and carbon dioxide (CO2) into energy-rich organic molecules such as sugars.
While photosynthesis supports nearly all life on Earth, it is quite inefficient with a typical plant converting just 1% of the light energy it absorbs into chemical energy.
The American team of bioengineers propose replacing photosynthesis with a solar-panel-powered chemical reaction that more efficiently converts CO2 into the organic molecule, acetate.
“Right now, we are at about 4% efficiency, which is already four times higher than for photosynthesis,” says senior author Feng Jiao of Washington University in Missouri in the US. “Because everything is more efficient with this method, the CO2 footprint associated with the production of the food becomes much smaller.”
The next hurdle for electro-agriculture is feeding plants with acetate, which is similar to the main component of vinegar.
To genetically engineer acetate-eating plants, Jiao and colleagues are targeting a metabolic pathway that young plants use to convert food stored in their seeds. This pathway is normally switched off once plants mature enough to photosynthesise.
“We’re trying to turn this pathway back on in adult plants and reawaken their native ability to utilize acetate,” says corresponding author Robert Jinkerson of University of California, Riverside.
“It’s analogous to lactose intolerance in humans—as babies we can digest lactose in milk, but for many people that pathway is turned off when they grow up. It’s kind of the same idea, only for plants,” adds Jinkerson.
So far, the team has focused on tomatoes and lettuce, and has succeeded in engineering plants that grow thanks to both acetate and photosynthesis. Ultimately, the goal is to engineer plants that get all their energy from acetate.
“If we don’t need to grow plants with sunlight anymore, then we can decouple agriculture from the environment and grow food in indoor, controlled environments,” says Jinkerson.
The bioengineers propose infrastructure similar to vertical farming but they highlight that electro-agriculture can occur in complete darkness and would not require prohibitively expensive lighting fixtures.
Electro-agriculture has many positive implications, such as rewilding large swathes of agricultural land, reducing fertiliser run-off, feeding a growing global population, increasing food security under climate change and even growing food in space.
“I think that we need to move agriculture into the next phase of technology, and producing it in a controlled way that is decoupled from nature has to be the next step,” says Jinkerson.
Major technological hurdles remain, particularly around genetically engineering plants that would grow exclusively on a diet of acetate. Since mushrooms and yeast can metabolise acetate naturally, the team recommend commercialising these species first.
“This is just the first step for this research, and I think there’s a hope that its efficiency and cost will be significantly improved in the near future,” says Jiao.
The research is published in the journal Joule.
