Mitigating cadmium accumulation in rice without compromising growth via modifying the regulatory region of OsNRAMP5

Abstract

Cadmium (Cd) intake poses a significant health risk to humans, and the contamination of rice grains with Cd is a major concern in regions where rice is a staple food. Although the knockout of OsNRAMP5, which encodes a key transporter responsible for Cd and manganese (Mn) uptake, can significantly reduce Cd accumulation in rice grains, recent studies have revealed that this knockout adversely affects plant growth, grain yield, and increases vulnerability to abiotic and biotic stresses due to reduced Mn accumulation. In this study, we employed CRISPR/Cas9 technology to modify the regulatory region of OsNRAMP5 with the aim of reducing Cd accumulation in rice grains. Our findings demonstrate that mutations in the regulatory region of OsNRAMP5 do not impact its expression pattern but result in a reduction in translation. The decreased translation of OsNRAMP5 effectively decreases grain Cd accumulation while leaving Mn accumulation and important agronomic traits, including yield, unaffected. Thus, our study presents a practical and viable strategy for reducing Cd accumulation in rice grains without compromising Mn accumulation or overall rice production.

Keywords

Cadmium accumulation / CRISPR/Cas9 / OsNRAMP5 translation / Oryza sativa (rice) / Regulatory region

References

[1] ClemensS, AartsMGM, ThomineS, VerbruggenN. Plant science: the key to preventing slow cadmium poisoning. Trends Plant Sci, 2013, 18: 92-99

[2] DongJ, WuT, SunY, HeH, LiY, PengY, JiZ, MengQ, ZhaoB, TangL. Effects of OsNRAMP5 mutation on heat tolerance and main economic traits of rice under the conditions of different manganese concentration. Hybrid Rice, 2021, 36: 79-88

[3] IshikawaS, IshimaruY, IguraM, KuramataM, AbeT, SenouraT, HaseY, AraoT, NishizawaNK, NakanishiH. Ion-beam irradiation, gene identification, and marker-assisted breeding in the development of low-cadmium rice. Proc Natl Acad Sci USA, 2012, 109: 19166-19171

[4] LeppekK, DasR, BarnaM. Functional 5 ’ UTR mRNA structures in eukaryotic translation regulation and how to find them. Nat Rev Mol Cell Biol, 2018, 19: 158-174

[5] PeiF, WangG, GaoP, FengZ, HuK, ChenZ, ChenH, CuiA, ZuoS. Evaluation of new japonica rice lines with low cadmium accumulation and good quality generated by knocking out OsNramp5. Chin J Rice Sci, 2023, 37: 16-28

[6] SasakiA, YamajiN, YokoshoK, MaJF. Nramp5 is a major transporter responsible for manganese and cadmium uptake in rice. Plant Cell, 2012, 24: 2155-2167

[7] SongY, WangYBN, MaoWF, SuiHX, YongL, YangDJ, JiangDG, ZhangL, GongYY. Dietary cadmium exposure assessment among the Chinese population. PLoS One, 2017, 12: e0177978

[8] TangL, MaoBG, LiYK, LvQM, ZhangLP, ChenCY, HeHJ, WangWP, ZengXF, ShaoY, PanYL, HuYY, PengY, FuXQ, LiHQ, XiaST, ZhaoBR. Knockout of OsNramp5 using the CRISPR/Cas9 system produces low Cd-accumulating indica rice without compromising yield. Sci Rep, 2017, 7: 14438

[9] TsukaharaT, EzakiT, MoriguchiJ, FurukiK, ShimboS, Matsuda-InoguchiN, IkedaM. Rice as the most influential source of cadmium intake among general Japanese population. Sci Total Environ, 2003, 305: 41-51

[10] YangCH, ZhangY, HuangCF. Reduction in cadmium accumulation in japonica rice grains by CRISPR/Cas9-mediated editing of OsNRAMP5. J Integr Agr, 2019, 18: 688-697

[11] ZhaoFJ, MaYB, ZhuYG, TangZ, McGrathSP. Soil contamination in China: current status and mitigation strategies. Environ Sci Technol, 2015, 49: 750-759

[12] ZhuHH, ChenC, XuC, ZhuQH, HuangDY. Effects of soil acidification and liming on the phytoavailability of cadmium in paddy soils of central subtropical China. Environ Pollut, 2016, 219: 99-106