José María García-Mina, researcher of the Biodiversity and Environment Institute and professor at School of Sciences, has collaborated in a study, led by the committee Superior Council for Scientific Research (CSIC), which has identified for the first time the molecular mechanisms used by plants to distinguish between phosphate, an essential nutrient for living beings, and arsenic, a carcinogenic compound present in a large part of soils and waters.

The work, which is published in the journal Molecular Plant, provides insight into how plants distinguish between beneficial nutrients and toxic elements with chemical similarities. This finding can help to obtain safer and healthier foods enriched in essential nutrients.

entrance In plants, arsenate and arsenite, the most abundant chemical forms of arsenic present in the biosphere, are easily incorporated into cells, allowing the metalloid to enter the food chain and threatening human health. "Arsenic in nature is mainly found as arsenate, a molecule very similar to phosphate, with which it shares the transporter entrance of these compounds into cells," explains Antonio Leyva, researcher of the CSIC at the National Center for Biotechnology (CNB-CSIC) and leader in this work. "While phosphate is metabolized by plants, arsenate is rapidly transformed into arsenite, a compound even more toxic than arsenate, but which, according to the results obtained, acts as a sensor and activates the defense response to poisoning," he adds.

Plant roots face continuous changes in the soil environment and require rapid and strict control of transporters to modulate the uptake of nutrients and toxic compounds. "In the presence of arsenate, the first reaction of plants is to prevent its entrance by 'shutting down' the common transporter," highlights Cristina Navarro, also a CSIC scientist at CNB-CSIC. "This repression leads the plant to a paradoxical status of phosphate fasting that compromises its survival, but at the same time prevents arsenic intoxication. Plants have a sophisticated mechanism of 'on and off' of the transporter that is very precise and is regulated according to the plant's detoxification capacity," says the researcher.

Cristian Mateo-Elizalde, researcher of the CNB-CSIC and co-author of work, stresses "the importance of obtaining foods enriched in essential elements, such as iron, zinc or magnesium, as opposed to others that are highly toxic for animals and humans, such as mercury, cadmium or arsenic, all of which are present in nature". Scientists point out that knowing the mechanisms to discriminate between toxic compounds versus other essential ones is fundamental in agriculture to obtain safer foods enriched in essential nutrients.

reference letter bibliographic

Navarro C., Mateo-Elizalde C., Mohan T.C., Sánchez-Bermejo E., Urrutia O., Fernández-Muñiz M.N., García-Mina J.M., Muñoz R., Paz-Ares J., Castrillo G. and Leyva A. Arsenite Provides A Selective Signal that Coordinates Arsenate Uptake and Detoxification Involving Regulation of PHR1 Stability in Arabidopsis thaliana. Molecular Plant. DOI: 10.1016/j.molp.2021.05.020