Scientists in the UK have discovered a mechanism in plants that can help crops develop long-term, natural immunity to stress caused by insect attacks and disease.
Researchers at the University of Sheffield found plants have the ability to remember stress for several weeks, and can prime themselves against future attacks.
The findings could pave the way for breeding more sustainable crop varieties that require fewer pesticides or insecticides, the scientists said.
In a study published in Nature Plants, researchers investigated the long-term effects of the plant stress hormone, jasmonic acid, on Arabidopsis thaliana, commonly known as thale cress — a relative cabbage and mustard.
When exposed to caterpillars, seedlings treated with jasmonic acid sustained lower levels of damage compared to the control group.
The scientists discovered the immune memory of being treated with jasmonic acid is encoded in a family of ‘junk DNA’ — DNA that doesn’t provide instructions for making plant proteins — which can prime defence genes for several weeks.
Those genes can also be transmitted to newly-developed leaves, providing long-lasting resistance against attack.
Professor Jurriaan Ton, from the university’s Institute for Sustainable Food, said the study’s findings provide a first model of long-lasting immune memory in plants, offering opportunities to reduce reliance on pesticides and other environmentally-harming inputs — a reduction that could have major environmental benefits.
“Like animals, plants have evolved the ability to acquire immunity after recovery from biotic stress, but they use different mechanisms to do so,” he said.
“The findings of the study are not only a huge leap forward in our understanding of how plants ‘remember’ the stress from previous attacks, but also uncovers a new epigenetic function of a specific family of junk DNA.
“This knowledge could help us to develop new breeding strategies, and select crop varieties for food production that are primed to fight off pests and diseases.”
Dr Sam Wilkinson, the study’s lead author, said the research could enhance crop breeding strategies, enabling growers to select plants that have ‘enhanced immune readiness’.
“The study has opened the way for us to develop a more precise and adjustable method to introduce beneficial epigenetic variation in plant genomes,” he added.
“This would not only be of value to crop protection and breeding, but also represent a valuable research tool to explore the complex mechanisms by which epigenetically altered DNA can prime defence genes within and across plant generations.”
The researchers are now collaborating with an international crop breeding company to investigate if they can exploit other related epigenetic mechanisms to prime crops against diseases.
