It is statistics such as these that have invigorated Scandinavian researchers, in particular the researchers at Sweden’s University of Gothenburg and Denmark’s University of Copenhagen, to investigate what can be done to help people in these afflicted regions to grow food.
Markus Tamas, a researcher at the Institute for Cell and Molecular Biology at the University of Gothenburg, together with Danish colleagues, has found the proteins responsible for arsenic absorption in plants. Up until now, scientists have been unable to identify which proteins are responsible for letting arsenite, the form of arsenic that damages cellular proteins, into plant cells. The discovery, which has been published in the scientific open access journal BMC Biology, opens up the possibility of reducing or preventing the absorption of arsenic by plants by using gene technology.
The joint research team is the first to present evidence that a family of transporters, called nodulin26-like intrinsic protein (NIPs), can move arsenite across a plant cell membrane. The researchers found that the growth of yeast containing certain plant NIPs was suppressed when arsenite, one of the predominant forms of arsenic found in soil, was added to the mix. They showed that the arsenite was channelled by NIPs and accumulated inside the yeast cells. Further investigations showed that only a subgroup of NIPs had arsenite transport capabilities, and have now been identified as metalloid channels in plants.
Arsenic is a global problem; it contaminates water, soil and crops in a large number of countries, with both developing and industrialised countries being affected. In some developing countries, high levels of arsenic in springs used for drinking water and irrigation have lead to alarmingly high amounts of toxin both in water and cultivated crops.
The scientists’ discovery could potentially lead to varieties of rice being bred which do not absorb arsenic even if watered with poisoned water. Through the application of gene technology they will be able to deactivate the proteins, or manipulate them in such a way so that the plant secretes the arsenic it absorbs. By limiting the absorption and storage of arsenic in rice, scientists should be able to reduce, at least partly, arsenic poisoning in humans by limiting how much of it comes from the food chain.
Attempts to develop rice varieties which absorb less arsenic are underway already, but this discovery of the particular proteins involved may lead to these developments accelerating.