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Researchers uncover how arsenic gets into the grain


Rice is a key food source in many parts of the world. However, it is not uncommon for it to contain arsenic. Biologists at FAU-Erlangen-Nürnberg have now found an approach that could help to reduce the amount of arsenic found in rice.

Every day millions of people around the world eat rice that contains arsenic. Even small concentrations of this toxic substance are a problem for those who eat large quantities of the grain - such as people in Asia where rice is a staple.

Arsenic finds its way into the plants through contaminated soil or ground water - usually in the form of arsenic trioxide, which is especially poisonous. The risk of crops becoming poisoned is particularly high in fields that are close to mines or metal works or where pesticides that contain arsenic are used.

Arsenic is absorbed by plants through their roots and spreads through the whole organism via their vascular system. Plants use this system to supply themselves with nutrients, transporting sugar produced in the leaves through photosynthesis to the roots or seeds, for example. However, a large proportion of the arsenic found in rice grains is also transported there in this way.

Transport proteins play a key role in this process. They act like gatekeepers, controlling access to different areas of the vascular system and guiding nutrients through the cell membranes. Together with colleagues from the Helmholtz Centre for Environmental Research in Leipzig, the Research Centre for Eco-Environmental Science in Beijing and Florida International University, researchers at FAU's Division of Molecular Plant Physiology have now identified two transport proteins that regulate the transport of the cyclic sugar alcohol inositol. While these two gatekeepers open the gates to cells to let in nutrients, they also allow in the toxic stowaways.

In the next stage of their research, the biologists aim to block the two transport proteins in rice plants to stop arsenic reaching the grains - without hindering the plants' growth. They have already succeeded in doing this in a model plant, arabidopsis, which is common in this part of the world, and now intend to apply their findings to rice plants. Their experiments could result in a new type of rice that would thrive on contaminated soil without allowing arsenic to enter the food chain.

» Original publication

Source: University of Erlangen-Nürnberg