Specialists treating cancer patients have long known that some cancers can resist certain anti-cancer drugs by rapidly pumping drugs out of tumour cancer cells. The anti-cancer drugs are pumped out before they have their toxic effect on cancer cells. These cellular pumps are coded for by ABC transporter genes that are present in animals and plants. The essential roles of these ABC transporter genes in humans are not fully understood and it is unfortunate that some of them can endow resistance to certain anti-cancer drugs, complicating cancer drug therapy.
ABC transporter genes are present in plants and now a specific ABC transporter has been shown to endow resistance to the herbicide glyphosate, in a similar way to the way these ABC transporters can give resistance to anti-cancer drugs in humans. A nasty weed species, Echinochloa, growing in the Kununurra Ord River region of WA developed resistance to the well-known herbicide glyphosate, after several years persistent use of glyphosate. In a world-first, this weed plant has been shown to resist glyphosate due to an ABC transporter that pumps glyphosate out of cells before it can have its toxic effect.
This is the first time that a plant ABC transporter has been found responsible for herbicide resistance. This plant ABC transporter giving the ability to resist glyphosate by pumping glyphosate out of cells is very similar to human ABC transporters pumping anti-cancer drugs out of cancerous cells.
The international team comprising researchers from the Australian Herbicide Resistance Initiative at the University of Western Australia, from Hunan Academy of Agricultural Science and Kiev, Ukraine definitively established that the ABC transporter gene endowed glyphosate resistance by expressing this gene in other plants.
They inserted the ABC transporter gene into rice, corn and soybean, which made these crop species able to pump glyphosate out of their cells and they became resistant to glyphosate. Control plants without addition of this ABC transporter gene were killed by glyphosate.
This intriguing similarity of ABC transporter genes conferring human cancer resistance to anti-cancer drugs and conferring plants with herbicide resistance adds to the need for both new, smarter chemicals and for alternative technologies if we are to continue to successfully combat scourges such as cancers, weed and other pest infestations that humans battle against.
This research was made possible through GRDC investment.