Master gene helps weeds defy all weedkillers
Date: 27.3.2013
No wonder wheat and barley farmers in Europe and Australia have trouble killing ryegrass and black-grass. These plants have a master gene that makes some strains resistant to all major herbicides.
"This is a general detoxification mechanism, just like the way tumours detoxify anticancer drugs," says Robert Edwards of the University of York, UK. The good news is, if the gene can be neutralised, it would take out the weeds' resistance at a stroke.
Most forms of herbicide resistance work by sabotaging the specific target against which a weedkiller acts. But the troublesome grasses have a gene called AmGSTF1, which makes an enzyme called a glutathione transferase. This causes the plant to make lots of protective antioxidants. These chemically neutralise many toxins in much the same way that human tumours – which also rely on glutathione transferases – can resist many drugs.
When Edwards transferred the AmGSTF1 gene from black-grass into thale cress, the cress became resistant to the herbicides. However, Edwards's team also discovered a solution: a drug called 4-chloro-7-nitro-benzoxadiazole. It is sometimes given to people with cancers that are resistant to many drugs, because it blocks glutathione transferases. When Edwards sprayed it on the weedkiller-resistant cress, the cress became vulnerable again.
