Scientists at theUniversities of York and Durham have discovered a gene called AmGSTF1 thatplays a key role in controlling multi-herbicide resistance (MHR) in black-grassand rye-grass. Chemicals that inhibit this gene can be used to make weedkillers effective against resistant weeds.
Black-grassand rye-grass are both widespread and serious weed problems in cereal andoilseed rape rotations. Control using herbicides is becoming increasinglyproblematic, with an estimated 1.2 million ha of UK land now infested withblack-grass. Both black-grass and rye-grass can acquire a single defencemechanism that confers resistance to all weed killers, whatever their mode ofaction (MHR).
Thegenetics of MHR has been little understood until now. But in recently publishedresearch, the scientists have shown that a gene producing an enzyme called glutathionetransferase (GST) is responsible for switching on MHR. When the gene was transferred to thale cress, thetransgenic plants became resistant. GSTsare known to detoxify herbicides directly, explains project leader ProfessorRob Edwards of the Centre forNovel Agricultural Products at the University of York, but we believe that our gene works as a masterswitch that activates a wide range of protective mechanisms.
When sprayed with a GST-inhibiting chemical, resistant plants becamesusceptible to herbicides. Although the compound used in these experiments isnot suitable for use as an agrochemical, this experiment demonstrates thepotential of GST inhibitors to improve the effectiveness of herbicides againstresistant black-grass and ryegrass.
Professor Edwards believes this to be an important development. These weeds have developed resistance to every typeof herbicide available to farmers and the problem is getting worse, heexplains. We have identified a group of compounds that could be applied alongwith existing herbicides to restore the effective weed control we are currentlylosing. Professor Edwards team is also developing a genetic test for AmGSTF1that could provide the first reliable diagnosis of MHR, an important step indeciding on the right weed control strategy.
This work was supported by joint funding from theUnited Kingdoms Biotechnology and Biological Sciences Research Council and bySyngenta.