Plants That Change Color in the Presence of Pesticides: A Scientific Breakthrough

• DNA

Plants have been communicating with us for centuries, but it's only now that we are truly starting to understand their language. In a pioneering study, a team of researchers at the University of California, Riverside, has genetically engineered plants to change color when exposed to a specific pesticide, providing an unambiguous readout of harmful environmental chemicals.

"Nature always wears the colors of the spirit." - Ralph Waldo Emerson.

Engineering Plants to Speak in Color

The plant in question, Arabidopsis thaliana, a small white-flowered plant from the mustard family, is commonly used as a model organism in plant biology labs. The researchers have manipulated the plant's natural stress response system to react to the presence of the pesticide azinphos-ethyl by changing color from green to red. This innovative technique significantly enhances our understanding of plant-environment interactions and presents a practical approach to environmental monitoring.

How Does It Work?

The team achieved this color change by hijacking a hormonal pathway that plants use to signal distress. Plants, including Arabidopsis, use abscisic acid (ABA) to send alerts when they're stressed by conditions like cold, drought, or changes in soil chemistry. The researchers rewired this pathway, altering the shape of the ABA receptor's binding pocket to detect and bind to azinphos-ethyl molecules.

To make the plant visibly change color, the researchers introduced a gene from beets into A. thaliana. This gene, part of a synthetic DNA sequence called RUBY developed by Yunde Zhao’s lab, contains instructions for making betalain, the bright red pigment that gives beets their signature color. When exposed to azinphos-ethyl, the modified plant activates RUBY, causing the leaves to turn from green to deep red. This visible color change signals the presence of the pesticide in the environment.

Expanding the Field of Biotechnology

This study is not just about creating color-changing plants; it's about broadening the capabilities of biotechnology. The researchers hope to engineer organisms capable of sensing various chemicals, which could provide real-time feedback about environmental conditions. For instance, plants could be engineered to change color in response to drought conditions before they suffer significant damage, providing a clear signal that they need water.

While the technology is currently restricted to the lab, the researchers are testing a range of other molecules, including pharmaceuticals, substances of abuse, natural plant products, and other agrochemicals. They hope to create biotechnologies that provide the public and other specific users with information on chemicals in the environment. This could include detecting contamination in local water supplies or identifying harmful chemicals used in industrial processes.

The Future of Transgenic Plants

Transgenic plants - those that contain DNA from other species - face rigorous approval processes due to concerns about potential unintended effects on the environment. However, recent approvals by the US Department of Agriculture for genetically modified crops suggest that, with further research, color-changing plants may also receive the green light. This innovative research opens up a world of possibilities for environmental monitoring and the broader field of synthetic biology.