Genetically engineering crops to be colorful could help farmers produce food without pesticides as it would make it easier to detect weeds, scientists said.
This will become increasingly important as hardy, climate-resistant “weeds” are cultivated for food in the future, the authors wrote in their report published in the journal Trends in Plant Science.
Lead author Michael Palmgren, a plant scientist from the University of Copenhagen, told the Guardian: “It could be changes in hair, leaf shape, light emitted at wavelengths we can’t see. Anything could work on a large scale. The challenge of distinguishing a weed from a crop becomes imminent when we start breeding weeds.”
He said new crops are difficult to distinguish from weeds, so it will be important to find a way to tell them apart. The paper suggests that the crops’ genomes could be altered so that they express pigments such as anthocyanins, which give blueberries their color, or carotenoids, which turn carrots orange.
“One example we give in our opinion document, fat hen (Chenopodium album), is cultivated for its nutritious seeds in India and Nepal and was a food source in Iron Age Europe – seeds are commonly found in the stomachs of bog bodies,” said Palmgren.
“Today it is a robust and competitive weed in European fields, capable of producing significant crop losses. Some scientists say: why not improve fat hen to make it a new sustainable crop that does not need much care? If this becomes a reality, how to distinguish the improved fat hen from the wild, weed fat hen? It is the same species and changes may only be noticeable after seeds have developed.”
Genetic science has helped to find the genes responsible for the desired traits that our ancestors selected for in crop plants, meaning that new crops with these traits can be bred much more quickly using genetic engineering. Many wild plants are more tolerant of extreme weather and other climate-related impacts than current crop plants, so breeding them can help prevent food shortages as the climate degrades.
However, these new crops are likely to resemble the weeds from which they are bred, so to make it easier without using pesticides, scientists propose creating visually distinctive plants that robotic weeders can easily distinguish from weeds.
“Distinguishing these new crops from their less productive and closely related wild plants can present tremendous challenges for weed control,” the researchers write. “Using gene editing to improve their visual recognition by weeding robots can effectively address this problem.”
