Rice blast, caused by the fungus Magnaporthe oryzae, destroys enough rice every year to feed about 60 million people. Researchers at the John Innes Centre in Norwich, working with Kobe University in Japan, have now engineered a class of plant immune receptors that recognise two different fungal effector proteins at once, an ability rarely seen in natural receptors. The work appeared in the journal Science Advances.
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The experiments are early. The engineered receptors were tested in wheat protoplasts, which are individual wheat cells, not in whole plants, and the team says greenhouse trials come next. What the result offers is a design method rather than a finished crop, and the distinction matters for how soon farmers could see any benefit.
A new receptor class beyond NLRs
Plant immunity research has concentrated for more than three decades on a family of receptors called NLRs. This study turns to a more recently discovered group, tandem kinase proteins, or TKPs, which can carry an extra piece called a Heavy Metal Associated, or HMA, domain. According to the John Innes Centre press release, HMA domains work as baits that lure effectors, the molecules the fungus injects into plant cells to suppress defences.
The team used biophysical analysis and crystallography to see at high resolution how an HMA domain grips an effector. That structural map is what allowed the engineering: with it, the researchers could change the receptor so that it binds effectors it would not normally recognise.
Prof. Mark Banfield, the group leader and senior author, who has studied blast for years, said the discovery “could lead to a potential intervention on what is the worst fungal disease of cereals.” First author Dr. Daniel Yu said the study indicates that this new class of resistance proteins is amenable to engineering, and that the tools previously used to engineer NLR receptors may also work with it.
Dual specificity against wheat and barley infections
The engineered TKPs were built to recognise two fungal effectors linked to infections in wheat and barley, a feature the researchers call dual specificity. The ScienceDaily release says this is unusual in natural immune receptors, and a 2019 John Innes Centre study of rice NLRs, covered below, noted that those receptors typically recognise only one type of effector, which limits how well a plant can cope with several at once.
The rice statistic and the wheat experiments come from different parts of the same story. Banfield has worked on blast in rice for years: in 2019, with researchers in Japan, his group showed that rice NLR receptors could bind two different effectors, AVR-Pik and AVR-Pia. The trade publication Food Ingredients First reported that work and put blast losses at up to a third of the global rice harvest, enough to feed about 60 million people each year. The new proof of principle is in wheat cells because the effectors studied were linked to wheat and barley infection.
Wheat blast is a distinct and growing worry. It was first identified in Brazil in the 1980s and has spread to parts of Asia and Africa, according to the press release. It is not in the UK, but the Centre says climate change could eventually threaten cereal production in northern Europe.
A separate 2024 John Innes Centre study shows how thin the available resistance is. Led by Dr Tom O’Hara and coordinated by Prof. Paul Nicholson, it screened more than 300 wheat varieties from the Watkins Collection and found only about 3% resisted blast strains carrying one key effector, and all of those carried the same gene, Pm4. O’Hara called it the first cloned blast resistance gene, and Nicholson said the findings were completely unexpected.
From protoplasts to whole plants
The next step is to move from protoplast assays to glasshouse plants, where the receptors will have to work inside intact tissue and against live infection. Banfield also proposes stacking TKP genes with NLR genes so a crop carries both receptor types, which he described as “making a super-resistant crop” and which he suggests would make it harder for the pathogen to evolve around the defences.
The team also plans to explore precision breeding and artificial intelligence approaches to engineer new HMA specificities, and to study other TKPs across diverse cereal crops. All of that remains planned work, and the press release frames it as proposals rather than results. The logic is that a plant carrying receptors of two different types would present the fungus with more than one hurdle, which is the same reasoning behind combining several resistance genes in conventional breeding. With only one known source of wheat blast resistance in the 2024 screen, even a modest widening of options would matter to breeders. The press release describes protoplasts as surrogates for whole tissue, which is a useful stand-in for a proof of principle but not the same as a living plant under attack, and no engineered line has yet been shown to resist blast in the greenhouse. The full paper in Science Advances sets out the data behind the claims.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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