Lucy Wright
A failed antibiotic molecule could have a new use in herbicides.
When an antibiotic developed to treat tuberculosis failed to progress out of the lab, scientists at the University of Adelaide, Australia, saw an opportunity in the fight against herbicide resistance.
Researchers at the university’s Herbicide and Antibiotic Innovation Lab have discovered that by tweaking its structure, the molecule has become effective at killing two of the most problematic weeds in Australia – annual ryegrass and wild radish.
The findings come as the rapid emergence and spread of herbicide-resistant weed populations prompt serious concerns over sustainable agriculture. ‘This discovery is a potential game changer for the agricultural industry. Many weeds are now resistant to the existing herbicides, costing farmers billions of dollars each year,’ said lead researcher Tatiana Soares da Costa from Adelaide’s Waite Research Institute.
This repurposing approach has the potential to fast-track new herbicide candidates to market. Soares da Costa noted: ‘Using failed antibiotics as herbicides provides a shortcut for faster development of new, more effective weed killers that target damaging and invasive weeds that farmers find hard to control.’
The research exploits similarities between plants and bacteria at a molecular level – specifically, the presence of an enzyme involved in the synthesis of the amino acid lysine. While inhibition of this enzyme was not found to kill bacteria, by altering the chemical structure of the inhibitor slightly, the team blocked production of lysine in weeds, halting their growth.
Targeting the synthesis of lysine is a novel mode of action for herbicides. Andrew Barrow, a postdoctoral researcher in Soares da Costa’s team commented: ‘There are no commercially available herbicides on the market that work in this way. In fact, in the past 40 years, hardly any new herbicides with new mechanisms of action have entered the market.’
The results provide a proof-of-concept that could impact agriculture worldwide. A spokesperson from CropLife UK, a membership organisation representing the UK plant science industry, said: ‘Any approach that can help identify useful new substances to help provide farmers with the tools they need in the future is welcomed.’
However, they note that the road to getting a new herbicide to market is a long one. ‘All plant protection products have to go through an extensive development process and rigorous regulatory assessment that takes many years before a product can be used.’
For Soares da Costa and her team, this is just the beginning – they are now looking at discovering more herbicidal molecules by re-purposing other failed antibiotics and partnering with industry to introduce new and safe herbicides to the market.
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