Plants are very susceptible to injury in many forms. They can’t hide from a hungry bunny rabbit or invasive fungi. As humans, we have “fight or flight” instincts, but flight is a tall order for plants. Instead, they have “fight or fix” instincts. When damaged plants have two responses, to repair and regenerate or defend. New York University’s Center for Genomics and Systems Biology decided to perform a study on this known quality of plants.

The defense method is the production of specific compounds, but the scientists’ experiment focused on the regeneration response. “Breeding crops that more readily regenerate and can adapt to new environments is critical in the face of climate change and food insecurity” said NYU professor and leader of the study, Kenneth Birnbaum. The study was split into two parts a study, and an experiment.

Early corn crop

The goal of the study was to understand the relationship between regeneration and defense responses. Does one happen or the other? Can they occur simultaneously? Does affecting one response have a subsequent affect on the opposing response?

The Scientists studied two plants; Arabidopsis and corn. Arabidopsis is common used as a model organism by plant biologists, while corn is the America’s largest crop. The answers they found to the previously posed questions are as follows. In most cases, both responses happen simultaneously and neither are at full strength. When the Scientists manually affected one of the responses, the other response did increase in frequency as a result. As Marcela Hernández Coronado of Cinvestav in Mexico put it, “The ‘fight or fix’ responses seem to be connected, like a seesaw or scales — if one goes up, the other goes down. Plants are essentially hedging their bets after an attack,”

The scientists were able to narrow down the cause of varying level of each response to plant glutamate receptor-like (GLRs) proteins. These receptors are related to glutamate receptors found in the human brain; hence the title of “Plant Therapists”. They learned that these receptors are responsible for regulating regeneration response and in turn, increasing defense response.

Competitive inhibitorConsidering the relationship with neural receptors, the scientists used preexisting drugs meant for these relative receptors. They used neural antagonists to inhibit GLRs. The antagonists are competitive inhibitors, that bind to the active site of the receptor blocking reception of signal molecules. The limited activity of the GLRs made the plants decide to heavily favor regeneration as the signals telling it otherwise were blocked.

The scientists also studied “quadruple mutants” in comparison to normal plants. The plants with mutated GLR had an increased rate of regeneration, further proving the effects of GLR on regulating the ratio between the two responses. Overall however, the plants that were given the neural antagonists were more successful in increased regeneration than the quadruple mutants.