Since the invention of weed killers, farmers have been caught in a never-ending arms race with weeds – from the moment of first spraying weeds start to develop resistance to the chemicals – and year on year, the armoury is shrinking.
Writing in the journal Plant Physiology, the group report they have used plant viruses to switch weed genes off, or alternatively, ramp up the production of specific proteins by weeds in the laboratory. Researchers can directly show that a specific gene is required for herbicide resistance, or else is sufficient to confer it.
A ‘game-changer’ for weed genetics, says the lead researcher
Lead researcher Dr Dana MacGregor’s latest study focuses on blackgrass, a major weed of cereals and a previous joint study involving Rothamsted, showed that herbicide resistant black-grass could cost US$1.24bn every year in the UK alone.
While researchers have previously identified genes that are over-represented in black-grass populations with herbicide resistance, there has been no way of genetically manipulating the weeds.
Dr MacGregor said, “Weeds are arguably one of the most economically important groups of plant species. They have major agronomic and environmental impacts and affect food security. To be able to design and deploy weed management strategies that are both effective and sustainable, we must first understand what genes allow black-grass to avoid the current control practices.”
“These virus-mediated techniques allow us to bring black-grass into the lab and ask questions about how specific genes works like we have never been able to before.”
Dr MacGregor’s team used two methods that were developed for studying crop plants, with both taking advantage of the pathways plants and their viruses use to fight one another. These are called Virus-induced gene silencing (VIGS) and Virus-mediated overexpression (VOX).
The team first inserted their gene of interest into a virus, and then infected the weed with it.
During VIGS, the plant tries to defend itself and in the process shuts down production of all genes coming from the virus - including the weed’s own copies of the inserted gene - whereas during VOX, both the virus’ and the inserted gene’s copies manufacture proteins for the plant.
“Of main importance will be to apply these techniques to establish a link between specific genes and ability of black grass to circumvent chemical controls, and thereby to gain a molecular level understanding of what allows black grass to be such a successful weed.”
This work was supported by the Smart Crop Protection Industrial Strategy Challenge Fund and the Biotechnology and Biological Sciences Research Council, part of UKRI.