Wild grass offers new genetic clues to combat deadliest pathogen of wheat

A new study has identified Aegilops cylindrica, a wild grass closely related to wheat, as a powerful genetic reservoir of resistance against the devastating fungal pathogen Zymoseptoria tritici, which causes Septoria tritici leaf spot (STB). These results open the door to breeding more resistant wheat varieties and reducing the world’s dependence on chemical fungicides.

The study is published in the journal Molecular plant-microbe interactions.

Unique Defense Mechanisms in Wild Herbs

The research team, led by Eva Stukenbrock of the Botanical Institute in Kiel, Germany, and the Max Planck Institute for Evolutionary Biology in Plön, Germany, discovered that A. cylindrica has unique defense mechanisms not found in cultivated wheat. By combining genetic and microscopic analyses, the researchers revealed that resistance to Z. tritici in this wild species is established at an early stage of infection, right at the stomatal openings of the leaf, where the fungus would normally enter.

Furthermore, transcriptome profiling revealed how virulent fungal isolates suppress key immune-related genes in A. cylindrica, whereas A. cylindrica maintains their expression when infected with avirulent and specialized wheat isolates to block infection.

Implications for livestock and agriculture

“What excites us most,” Stukenbrock noted, “is that Aegilops cylindrica provides entirely new information on plant immunity to Z. tritici that was previously unknown in wheat. This discovery provides breeders with new targets to improve resistance and develop more sustainable control strategies.”

This is the first study to generate a transcriptome assembly for A. cylindrica, a species with a simpler genome but with strong parallels to wheat pathogen interactions. The results not only highlight new candidate resistance genes, but also shed light on how Z. tritici overcomes plant defenses by suppressing key immune responses – a process Stukenbrock calls “molecular sabotage.”

A broader impact on food security

Beyond its implications for wheat improvement, this work advances the understanding of plant pathology, genetics and sustainable agriculture. This highlights the importance of conserving wild plant relatives as sources of hidden traits that can help secure the global food supply.

“This research expands our view of plant-pathogen interactions and provides a roadmap for developing wheat varieties capable of resisting one of the world’s most damaging cereal diseases,” the team explained.