This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A UK-led research collaboration has taken a significant step in the global effort to protect cereal crops from the devastating blast fungus. Researchers at the John Innes Centre explored a recently discovered class of plant defense receptors, showing at the molecular level how they limit blast pathogen attacks and how they might be bioengineered to provide broader, more durable immunity in wheat, barley and rice.
"We've discovered something that could lead to a potential intervention on what is the worst fungal disease of cereals," said Mark Banfield, a professor and group leader at the John Innes Centre and an author of the study, conducted with researchers at Kobe University in Japan. The blast fungus, Magnaporthe oryzae, causes the most serious disease of cultivated rice and has spread to wheat and barley in parts of Asia and Africa. Innovative solutions to prevent it are essential to global food security.
To infect plants, pathogens such as Magnaporthe oryzae insert effectors into leaf and stem cells to manipulate the host and promote disease. Plants have receptors that recognize effectors as foreign molecules and prompt an immune response that initiates localized cell death to limit the pathogen's spread through the plant. For more than 30 years, a considerable body of research has focused on a class of immune receptors called nucleotide-binding and leucine-rich receptors (NLRs).
They have been at the forefront of our understanding of plant immune responses to blast and other diseases. In recent years, studies have increasingly focused on a new class of intracellular immune receptors discovered in cereals called tandem kinase proteins (TKPs). Previous research has shown that TKPs can contain an integrated heavy metal-associated (HMA) domain, a feature also seen in some NLR receptors.
The domain has been shown to be important for recognizing effectors and mounting an immune response. "This piqued our interest," Banfield 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 front line for defense of plants against disease." In this study, published in Science Advances, the group used biophysical analysis and crystallography to reveal at high resolution the structural interaction between HMA domains and blast pathogen effectors.
The researchers showed how HMA domains play a critical role in TKPs by acting as biological baits to lure pathogen effectors. Using that structural knowledge, they successfully bioengineered TKP immune receptors to have dual specificity—binding to effectors associated with infection of both wheat and barley, something that does not happen often in nature. By demonstrating that TKPs are amenable to bioengineering, the study sets the stage for further research into many recently discovered TKPs in diverse cereal crops.
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