Researchers at the University of Sheffield have uncovered how plant immune memory can persist while protecting genome stability. The findings, alongside early results in rice, point to potential applications in epigenetic crop breeding, offering new ways to develop disease resistance, stress tolerance and other valuable traits.
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Sheffield researchers have identified how plants retain disease defences while protecting their genomes, with early rice findings pointing to potential applications in epigenetic breeding.
Understanding how plants remember infections could give crop breeders new ways to develop disease resistance and other valuable traits by changing how existing genes are regulated.
A study published in Nature Communications, led by Professor Jurriaan Ton and Dr Adam Hannan Parker at the University of Sheffield, has identified mechanisms that help plants maintain and reset immune memory.
The findings could expand the variation available to breeders, supporting efforts to develop crops better equipped to withstand disease and environmental stress.
How Plants Remember Disease
Plants lack the specialised immune cells found in animals, but previous infections can prepare their defence systems to respond more quickly and strongly to subsequent attacks.
Earlier research from the Ton laboratory found that plants store this memory by removing chemical tags attached to their DNA. These tags influence gene expression without changing the underlying DNA sequence.
An enzyme called REPRESSOR OF SILENCING 1 (ROS1) removes the tags, helping plants retain an epigenetic memory of past threats.
In the new study, researchers used a molecular tool called XVE to activate ROS1 more precisely than infection allows. This experimental “plant vaccination” tool enabled them to investigate how immune memory develops, how long it lasts and how it is erased, according to a press release.
Retaining Defences While Protecting the Genome
Activating ROS1 presents a challenge: removing chemical tags could also activate genetic elements that are normally kept silent.
“Too much ROS1 activity carries a potential risk. It can release silenced transposons, or ‘jumping genes’, which move within the genome and cause mutations. These elements are particularly abundant in pericentromeres, the regions surrounding the constricted centres of chromosomes,” Parker said.
The researchers discovered that plants can retain immune memories while protecting their overall DNA stability.
Following ROS1-triggered vaccination, plants temporarily redirect their DNA-silencing machinery away from defence genes and towards chromosome regions rich in transposons. This keeps jumping genes suppressed while allowing defence genes in the chromosome arms to retain their epigenetic memory.
Early Rice Findings Point to Breeding Potential
For breeders, the potential lies in generating useful variation in gene regulation alongside the DNA sequence differences targeted through conventional breeding.
“Conventional crop breeding mainly selects for differences in DNA sequence. By changing the distribution of DNA methylation, the tool could instead generate epigenetic variation that alters how existing genes are regulated. Our collaboration with researchers at the Okinawa Institute of Science and Technology (OIST) in Japan is revealing promising results in rice, suggesting the epigenetic memory by XVE in rice is not completely reset between generations, with part of it transmitted to offspring,” Ton said.
The Sheffield team is now refining the tool to deliver a stronger “epigenetic shock”, aiming to generate variation that remains stable across generations. Breeders could then screen plants for beneficial traits.
Looking Beyond Disease Resistance
The potential applications extend beyond preparing plants to fight infection.
“Potential targets go beyond disease resistance alone and could include tolerance to abiotic stresses, such as drought, heat or salinity. The approach could also help generate variation in other complex quality traits, including the nutritional value of vegetable crops and compounds with potential health benefits.”
Further research is needed to establish how reliably useful changes can be generated and inherited. If successful, the approach could give breeders an additional source of variation for improving crop resilience and quality.
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