By Desire Uzochukwu
Scientists have developed an experimental approach to strengthening the natural immune defenses of wheat, rice and barley against a destructive fungus that threatens global food security, raising hopes for more resilient crops and better protection of future harvests.
The breakthrough, led by researchers at the John Innes Centre in the United Kingdom, could pave the way for crops capable of recognising and fighting multiple fungal threats by engineering a previously underexplored class of plant immune proteins.
The research focuses on Magnaporthe oryzae, the fungus responsible for blast disease, one of the most destructive fungal diseases affecting cereal crops. Rice blast alone destroys enough rice annually to feed approximately 60 million people, while wheat blast has emerged as a growing threat in parts of Asia and Africa.
The findings, published in Science Advances, demonstrate that scientists can modify tandem kinase proteins (TKPs), a class of plant immune receptors, to recognise two different fungal molecules associated with infections in wheat and barley.
Professor Mark Banfield, a research group leader at the John Innes Centre and an author of the study, described the discovery as a potential turning point in the fight against cereal fungal diseases.
“We’ve discovered something that could lead to a potential intervention on what is the worst fungal disease of cereals,” Banfield said.
The international research involved collaborators at Kobe University in Japan and offers a new avenue for developing crops with stronger and potentially more durable resistance to fungal infections.
The findings come amid growing concern over the spread of blast disease into new agricultural regions, threatening crops that are essential to feeding millions of people.
How scientists plan to outsmart the fungus
Fungi responsible for blast disease attack plants by releasing specialised molecules known as effectors into their cells. These molecules interfere with normal plant functions, helping the pathogen establish an infection and spread disease.
Plants, however, possess immune receptors that can detect these invading molecules and activate protective responses, including the controlled death of infected cells to limit the spread of the pathogen.
For more than three decades, much of the research into plant immunity has focused on nucleotide-binding and leucine-rich repeat receptors, commonly known as NLRs.
The new study investigates tandem kinase proteins, which researchers believe could provide an additional route to strengthening crop defences.
The scientists were particularly interested in a specialised region of some TKPs known as the Heavy Metal Associated (HMA) domain. Similar domains occur in certain NLR receptors and can help plants recognise molecules released by invading pathogens.
Banfield said the discovery raised the possibility of redesigning these domains to recognise fungal threats that plants might otherwise fail to detect.
“This piqued our interest,” he said. “If we can engineer these integrated HMA domains for new properties by making amino acid protein changes where effectors bind, we can gain what we call novel recognition specificities — and potentially a new frontline for defence of plants against disease.”
To investigate the possibility, the researchers used biophysical techniques and crystallography to examine how the immune receptors interact with fungal effectors.
The structural analysis provided a detailed picture of how the proteins bind to the fungal molecules, revealing how the HMA domains can act as biological bait, detecting components used by the pathogen during infection.
Using this information, the team modified TKP immune receptors to recognise two different fungal effectors associated with infections in wheat and barley.
The ability to recognise two targets, described as dual specificity, could help broaden the range of fungal threats that a plant’s immune system can detect.
‘A new class of resistance proteins’
Dr Daniel Yu, the study’s first author, said the findings demonstrated that the newly investigated proteins could be engineered using approaches previously applied to other plant immune receptors.
“Our study indicates that this new class of resistance proteins is amenable for engineering purposes. We now know that the previous tools we used in engineering NLR receptors may also work with this new class,” Yu said.
However, the research remains at an early experimental stage. Initial tests were conducted using protoplasts, individual plant cells that provide a simplified model for studying immune responses.
The next step is to establish whether the modified receptors can protect whole plants under controlled greenhouse conditions and, subsequently, whether the approach can deliver reliable resistance under real agricultural conditions.
The researchers also see opportunities to combine precision breeding and artificial intelligence with their findings to redesign HMA domains to recognise fungal molecules that currently evade plant defences.
Such advances could eventually allow scientists to develop customised immune receptors targeting several fungal threats simultaneously.
Scientists eye more durable crop protection
One of the study’s most promising possibilities is combining TKPs with NLR receptors in the same crop to create multiple layers of defence.
The two classes of receptors appear to activate plant immunity through different mechanisms. Combining them could make it more difficult for fungi to overcome a crop’s defences through evolutionary changes.
“We think these two classes of immune receptors, NLRs and TKPs, are probably activated in different ways,” Banfield said.
“That gives the potential for more robust immunity in the field because you are not putting all your eggs in one basket.”
He added: “Further down the road, we may be able to use techniques to stack genes encoding TKPs and NLRs together against the same disease, making a super-resistant crop. They will have different ways of activating immunity, so it is likely to be more difficult for a pathogen to evolve away from.”
The potential benefits are significant for countries that depend heavily on cereal crops for food and livelihoods, particularly as blast disease spreads into new agricultural regions.
Wheat blast was first identified in Brazil in the 1980s and has since spread to parts of Asia and Africa. Although it has not been detected in the United Kingdom, the researchers noted that climate change could eventually create conditions favourable to the disease in northern Europe.
For farmers, the emergence of the disease in new regions presents a serious challenge because the fungus threatens crops that are central to feeding large populations.
The researchers cautioned, however, that further work is needed to establish whether the engineered immune receptors can deliver effective, lasting protection in whole plants and under field conditions.
If successful, the approach could provide scientists with new tools to develop wheat, rice and barley varieties better equipped to withstand destructive fungal infections, helping to protect future harvests and strengthen global food security.
