Turning failed antibiotics into weedkillers

Dr Tatiana Soares da Costa, School of Agriculture, Food and Wine, Waite Research Institute, University of Adelaide

Weeds are popping up everywhere! Not just in our backyards, but also in farms all around Australia and the world. Weeds reduce the quality and size of food harvests, costing Australian farmers over $5 billion every year and driving up food prices. We rely on chemical weedkillers called herbicides to control weeds. However, the existing herbicides on the market are failing as weeds have become resistant. To make matters worse, very few new herbicides have entered the market in the past 40 years. As the world population is set to pass 10 billion people by 2050, how are we going to keep feeding people if weeds are winning the war against crops?

I lead a research team at the University of Adelaide that is turning failed drugs into new, environmentally friendly weedkillers to safeguard food production. This innovation started in 2019, when I was researching news ways to make drugs to kill deadly bacteria called superbugs. I made molecules that could block a bacterial protein, but sadly, they didn't kill the superbugs. Total failure, right? Or not....I realised that the protein we were targeting in superbugs was also found in weeds, and that the proteins looked very similar. Instead of giving up, I tested our molecules as weedkillers. And voila! We showed that our failed drugs could kill weeds that farmers can no longer control with current products. Excitingly, our herbicides are highly specifically to weeds, with no effects on human, animal or microbial cells.

My team has now expanded this discovery to show that weeds can be killed with other molecules that have been designed to kill superbugs. Using failed drugs as herbicides is a game-changer in the agricultural industry as it can help us develop herbicides quicker and cheaper by leveraging the research already done on superbugs and applying it to weeds. Because these molecules can't kill bacteria, they won’t lead to antibiotic resistance. This just goes to show that what looks like a dead-end might be a hidden corner instead!

Funding for this research program has been provided by the Australian Research Council through a Discovery Project (DP220101901) and Future Fellowship (FT230100203) awarded to Dr Tatiana Soares da Costa.

Photo legend: Members of the Soares da Costa research group (from left to right). Dr Andrew Barrow (postdoctoral researcher), Dr Emily Mackie (postdoctoral researcher), Sreshtha Malik (PhD student), Olivia Oh (PhD student), Art Hussnain (MPhil student), Ryan McClean (PhD student), Mirrin McKay (PhD student) and Dr Tatiana Soares da Costa (Laboratory Head).