Through their roots, plants draw the nutrients necessary for their growth from the soil. Although phosphorus is an essential part of life, the soluble form (phosphate) that plants can absorb is often present in the soil in only limited quantities.

Researchers at CEA-BIAM, IBS, CNRS and the Leibniz Institute of Plant Biochemistry in Halle, Germany, have discovered a mechanism activated by phosphate deficiency that inhibits the growth of the main root of plants. They identified how the plant inhibits the growth of its main root when it encounters a low-phosphate zone and how, concurrently, lateral root growth is stimulated.

According to the study, when the tip of the main root encounters a phosphate-deficient medium, the production of a protein allowing the cells to release malate into the extracellular medium is stimulated. Malate is a small organic acid capable of binding to metal ions such as iron. The association of malate and iron very rapidly triggers a reaction that, via ferroxidase, leads to blocked root cell elongation and division.

This discovery would make it possible to select plants that are better adapted to low-phosphate soils for more sustainable agriculture. In addition, organic acids such as malate support the solubilization of metals such as cesium and uranyl (a uranium oxide) in soils and, consequently, their uptake by the plant. The stimulation of this mechanism in roots could, therefore, prove to be a new strategy to improve the phytoextraction of these polluting metals.

This result was the subject of a press release.