A A molecule that was initially developed to treat tuberculosis but failed to make it out of the lab as an antibiotic is now showing promise as a potent enemy to the weeds that overrun our gardens and cost farmers billions of dollars each year.

Although the failed antibiotic was not suited to its original purpose, scientists at the University of Adelaide found that by modifying its structure, the molecule became effective at killing two of Australia’s most problematic weeds, ryegrass and radish. wild, without harming bacteria and humans. cells.

Annual ryegrass (Lolium rigidum) is one of the most serious and costly weeds of annual winter cropping systems in South Australia. Credit: Western Australian Government

This discovery is a potential game changer for the agricultural industry. Many weeds are now resistant to existing herbicides on the market, which cost farmers billions of dollars each year, said lead researcher Dr Tatiana Soares da Costa of the University of Adelaides Waite Research Institute.

The use of failed antibiotics as herbicides provides a shortcut to faster development of new, more effective herbicides that target harmful and invasive weeds that farmers find difficult to control.

Researchers at the university’s Herbicide and Antibiotic Innovation Lab found that there were similarities between bacterial superbugs and weeds at the molecular level.

They exploited these similarities and, by chemically modifying the structure of a failed antibiotic, managed to block the production of the amino acid lysine, which is essential for weed growth.

Monomeric crystal structure of AtDHDPR1 aligned with the C chain of the dimeric crystal structure AtDHDPR2. Credit: University of Adelaide

There are no commercially available herbicides on the market that work this way. In fact, over the past 40 years, there have been almost no new herbicides with novel mechanisms of action that have entered the market, said Dr. Andrew Barrow, a postdoctoral researcher in Dr. Soares da Costas’ team at the University of Adelaides Waite Research Institute.

Weeds are estimated to cost the Australian agricultural industry more than $5 billion a year.

“The use of failed antibiotics as herbicides provides a shortcut to faster development of new, more effective herbicides that target harmful and invasive weeds that farmers find difficult to control.”

Dr Tatiana Soares da Costa of the University of Adelaides Waite Research Institute.

Annual ryegrass in particular is one of South Australia’s most serious and costly weeds.

The shortcut strategy saves valuable time and resources and thus could accelerate the commercialization of much-needed new herbicides, said Dr. Soares da Costa.

It is also important to note that the use of failed antibiotics will not lead to antibiotic resistance because the herbicidal molecules we have discovered do not kill bacteria. They specifically target weeds, with no effect on human cells, he said.

Not only farmers could reap the benefits of this discovery. Researchers say it could also lead to the development of new herbicides to target the pesky weeds growing in our patios and driveways.

Our repurposing approach has the potential to uncover herbicides with broad applications that can kill a variety of weeds, Dr Barrow said.

This research was published in the journal ofCommunication biology