Exeter researchers discover a novel chemistry to protect our wheat and rice from fungal disease

15% of global crop production is lost to plant diseases annually. To increase the world’s food security and save resources, many scientists in the world are doing their best to invent new ways to combat these diseases. Finding new compounds is challenging, as they need to be toxic to fungi but must not be harmful to the plants treated with them, humans consuming the food, or aquatic organisms. They must also target more than one process in the fungus cells, otherwise, a single mutation can introduce resistance into the fungus rendering the whole process ineffective.

A team at the University of Exeter, led by Professor Gero Steinberg, has discovered a novel fungicide to protect against a fungus called Zymoseptoria tritici. This fungus causes Septoria leaf blotch in wheat and rice plants. The team has discovered the mode of action of mono-alkyl lipophilic cations (MALC), which target the mitochondria, the “powerhouses of the cell”, stopping fungal respiration and energy production. They found that MALC are attracted to the negatively charged inner membrane of the mitochondria, where they insert themselves. This way then can distort the essential proteins fungi need to survive. Working from there they designed and tested more compounds, which they found had additional modes of action, including the production of Reactive Oxygen Species leading to mitochondrial damage and programmed cell death. Additionally, the compound also appears to “alert” the plant defensive system, which then produces hydrogen peroxide to protect the plant from pathogen invasion. This very broad effect makes the fungicide a very powerful compound for combating plant disease.

Professor Sarah Gurr, one of the team members, said: “This is such a timely and important study. We are increasingly aware of the growing burden of plant disease caused by fungi and of our need to safe-guard our calorie and commodity crops better.

“The challenge is not only to discover and describe the mode of action of new antifungals but to ensure that chemistries potent against fungi do not harm plants, wildlife or human health.”

“This new antifungal is thus an exciting discovery and its usefulness may extend beyond crops into the realms of fungal disease in humans and, indeed to various applications in the paint and preservative industries.”

Because fungal and mammalian mitochondria differ significantly, the new fungicides shouldn’t affect humans. Indeed, tests showed that these new chemicals had little effect on human cells, being even less toxic than some commercially used products. They were also safe to plants and aquatic life and didn’t induce any mutations.

The University of Exeter has filled out a patent and is now searching for interested investors. Professor Gero Steinberg said: “Our long-term aim is to foster greater food security, in particular in developing nations”. Hopefully this goal can be fulfilled and this new compound can soon start protecting our crops.

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