A fluorescent microscopy image of a root.
Roots of bioengineered plants sense and respond to microbial signals.
Alice Boo (MIT).

At the macroscopic level, plants do not appear terribly active, but below the ground is a maelstrom of microscopic activity, as root systems send and receive a diverse array of chemical signals from bacteria and fungi in the soil. 

While this bidirectional communication seems to be crucial for plant health, the exact identities and functions of these chemical messengers are not well understood. To circumvent this problem, researchers at the Massachusetts Institute of Technology led by synthetic biologist Christopher Voigt bioengineered a new communication channel between microbes and plants. Published recently in Nature Communications, their work demonstrates that environmental sensors can be “outsourced” to bacteria to create a plant-microbe team that can rapidly respond to threats.1

Researchers engineered bacteria to produce a signaling molecule called molecule p-coumaroyl-homoserine lactone (pC-HSL) in response to different chemical stimuli. They also engineered plants—first the model species Arabidopsis thaliana, and then the potato—to turn on a fluorescent signal when they detected pC-HSL. In this way, researchers could change the environmental stimuli that a plant responds to simply by pairing it with different types of sensor bacteria. The bacteria could even be engineered to perform simple signal processing, integrating information from two different sensor types.

          a headshot of Christopher Voigt against a white background.
Christopher Voigt engineers genetic circuits with applications in agriculture, therapeutics, and living materials.
Christopher Voigt

Plants producing a fluorescent signal is not the end goal of this project, however, said Voigt. “I want to do sense and respond for stresses and pathogens,” he said. “Instead of trying to engineer the plant to solve a problem, it sends the signal to the bacteria, and the bacteria solve it for them. Or the bacteria sense something in the soil and send the signal that this has to be dealt with to the plant.”

Eriko Takano, a synthetic biologist at the Manchester Institute of Biotechnology who was not involved in the study, believes that these technologies could reduce reliance on herbicides, fungicides, or insecticides by providing an alternative way for plants and their associated microbes to respond to threats.  

“It's very nice work,” she said. “It's really [taking steps] towards making healthier soil without using pesticides.”

Reference

  1. Boo A et al. Nat Commun. 2024;15(1):1817.