Production of low-Cs+ rice plants by inactivation of the K+ transporter OsHAK1 with the CRISPR-Cas system

Manuel Nieves-Cordones (1, 2) , Sonia Mohamed (1, 3) , Keitaro Tanoi (4, 5) , Natsuko I. Kobayashi (4) , Keiko Takagi (4) , Aurore Vernet (3) , Emmanuel Guiderdoni (3) , Christophe Périn (3) , Herve Sentenac (1) , Anne-Aliénor Véry (1)

1 BPMP - Biochimie et Physiologie Moléculaire des Plantes
2 Departamento de Nutrición Vegetal
3 Cirad - Centre de Coopération Internationale en Recherche Agronomique pour le Développement
4 Graduate School of Agricultural and Life Sciences
5 Japan Science and Technology Agency (JST)

Occurrence of radiocesium in food has raised sharp health concerns after nuclear accidents. Despite being present at low concentrations in contaminated soils (below μM), cesium (Cs+) can be taken up by crops and transported to their edible parts. Such a plant capacity to take up Cs+ from low concentrations has notably affected the production of rice (Oryza sativa L.) in Japan after the nuclear accident at Fukushima in 2011. Several strategies have been put into practice to reduce Cs+ content in this crop species, such as contaminated soil removal or adaptation of agricultural practices, including dedicated fertilizer management, with limited impact or pernicious side effects. On the other hand, development of biotechnological approaches aiming at reducing Cs+ accumulation in rice remained challenging. Here, we show that inactivation of the Cs+-permeable K+ transporter OsHAK1 with the CRISPR-Cas system dramatically reduced Cs+ uptake by rice plants. Cs+ uptake in rice roots and in transformed yeast cells expressing OsHAK1 displayed very similar kinetics parameters. In rice, Cs+ uptake is dependent on two functional properties of OsHAK1: (i) a poor capacity of this system to discriminate between Cs+ and K+, and (ii) a high capacity to transport Cs+ from very low external concentrations, which is likely to involve an active transport mechanism. In an experiment with a Fukushima soil highly contaminated with 137Cs+, plants lacking OsHAK1 function displayed strikingly reduced levels of 137Cs+ in roots and shoots. These results open stimulating perspectives to smartly produce safe food in regions contaminated by nuclear accidents.

Mots clés: rice; cesium; HAKI; CRISPR-Cas; soil contamination by radioactivity; root absorption; radioactive contamination

Mots clés: radiocesium; oryza sativa; absorption racinaire; contamination environnementale; contamination radioactive

Domaines: Biologie végétale

Manuel Nieves-Cordones, Sonia Mohamed, Keitaro Tanoi, Natsuko I. Kobayashi, Keiko Takagi, et al.. Production of low-Cs+ rice plants by inactivation of the K+ transporter OsHAK1 with the CRISPR-Cas system. Plant Journal, 2017, 92 (1), ⟨10.1111/tpj.13632⟩. ⟨hal-01581607⟩