How wheat creates a chemical defence to disease

Wheat defends itself against disease by producing chemicals, new research has led to the discovery of the several sets of genes that are switched on in response to an attack and a new molecule named ellarinacin.

The research by the Osbourn and Uauy groups of the John Innes Centre leveraged recent advances in mapping of bread wheat’s complex genome to make the discovery.

Wheat is one of the most important cereal crops and supplies one fifth of the calories consumed by humans worldwide. Despite its agricultural importance, little is known about the chemicals wheat produces in response to pest and pathogen attacks.

Knowing genetic pathways produce certain useful chemicals means that these gene combinations could be bred into wheat varieties to make them more resistant to diseases at a time when climate change is making this more of a problem

New pathways

The researchers discovered six pathogen-induced biosynthetic pathways that share a common regulatory network and form part of an orchestrated defence response.

Investigation of the wheat genome reveals that these pathways are each encoded by biosynthetic gene clusters (BGCs) that produce flavonoids and terpenes. These chemicals may serve as phytoalexins or defence-related signalling molecules. The results provide key insights into the molecular basis of biotic stress responses in wheat and open potential avenues for crop improvement.

New chemicals 

Professor Anne Osbourn, a Group Leader at the John Innes Centre and an author of the paper said: “From knowing little about wheat defence compounds, we have now discovered six previously unknown pathways for biosynthesis of defence compounds in wheat, including entirely new chemicals that haven’t been reported before.

“Our work continues, to investigate what these molecules are doing in wheat, how they contribute to defence against pathogens, and how the whole network of pathogen-induced gene clusters is regulated.”

Pathogen-induced Biosynthetic Pathways Encode Defence-Related Molecules in Bread Wheat appears in PNAS.