Plants are subject to many attacks and injuries, from rabbits or caterpillars munching on their leaves to fungi or grubs attacking their roots. While animals can employ “fight or flight” responses when attacked, plants cannot run. Instead, according to a new study led by New York University’s Center for Genomics and System Biology, injury triggers a “fight or fix” response in plants, prompting them to either regenerate their damaged or missing parts, or to defend themselves by rapidly producing chemicals designed to stop animals or pathogens from further attacks.
Better understanding how plants regulate the trade-off between repairing damaged tissue and ramping up their defenses enabled scientists to nudge wounded plants towards repair rather than defense, a strategy which can be useful in improving crop regeneration.
In order to investigate how plants regulate these responses, the researchers cut off parts of several specimens of Arabidopsis, a small plant widely used as a model organism in Plant Biology, and corn, America’s largest crop and a very important source of nutrition for both people and animals. They found that, after an injury, plants produced some regeneration and some defense response, but did not ramp up both to maximum capacity. In fact, lowering one response appeared to increase the other.
“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,” said study lead author Marcela Hernández Coronado, an expert in Plant Molecular Biology at the Center for Research and Advanced Studies of the National Polytechnic Institute in Mexico.
The scientists discovered that the balance in regeneration and defense responses was regulated by plant glutamate receptor-like (GLRs) proteins, which are distant relatives to glutamate receptors found in animal and human brains. Understanding the essential role these proteins play in the plants’ responses to injury presents a unique opportunity to improve plant growth, especially in cereal crops such as corn, sorghum, or wheat, which are particularly resistant to regeneration.
“These glutamate receptors provide a ‘druggable target’ that we can use to enhance plant regeneration and propagation,” explained study senior author Kenneth Birnbaum, a professor of Biology at NYU.
By using both genetic interventions and three types of neuronal antagonist drugs to inhibit GLR activity, Professor Birnbaum and his team managed to alter the plants’ decision-making process in favor of regeneration.
“Retuning the balance between plant defense and regeneration could be used to improve regeneration for biotechnology, conservation, and propagation of staple food crops. Breeding crops that more readily regenerate and can adapt to new environments is critical in the face of climate change and food insecurity,” Professor Birnbaum concluded.
The study is published in the journal Developmental Cell.