Hunan Provincial Key Laboratory of Phytohormones and Growth Development, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China.
State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Changsha, 410125, China.
Sci Rep. 2017 Oct 31;7(1):14438. doi: 10.1038/s41598-017-14832-9.
Rice grain with excessive cadmium (Cd) is a major source of dietary Cd intake and a serious threat to health for people who consume rice as a staple food. The development of elite rice cultivars with consistently low Cd content is challenging for conventional breeding approaches, and new strategies urgently need to be developed. Here, we report the development of new indica rice lines with low Cd accumulation and no transgenes by knocking out the metal transporter gene OsNramp5 using CRISPR/Cas9 system. Hydroponic culture showed that Cd concentrations in shoots and roots of osnramp5 mutants were dramatically decreased, resulting in rescue of impaired growth in high Cd condition. Cd-contaminated paddy field trials demonstrated that Cd concentration in osnramp5 grains was consistently less than 0.05 mg/kg, in contrast to high Cd concentrations from 0.33 mg/kg to 2.90 mg/kg in grains of Huazhan (the wild-type indica rice). In particular, the plant yield was not significantly affected in osnramp5 mutants. Furthermore, we developed promising hybrid rice lines with extremely low Cd content in grains. Our work supplies a practical approach to developing Cd pollution-safe indica rice cultivars that minimizes Cd contamination risk in grains.
过量镉（Cd）污染的大米是膳食 Cd 摄入的主要来源，也是以大米为主食的人群健康的严重威胁。利用传统的育种方法培育始终保持低 Cd 含量的优质水稻品种具有挑战性，因此迫切需要开发新的策略。在这里，我们利用 CRISPR/Cas9 系统敲除金属转运蛋白基因 OsNramp5，开发出不含转基因且 Cd 积累量低的新型籼稻品系。水培实验表明，osnramp5 突变体的地上部和根部 Cd 浓度显著降低，从而挽救了在高 Cd 条件下生长受到的抑制。Cd 污染稻田试验表明，osnramp5 稻米中的 Cd 浓度始终低于 0.05mg/kg，而对照品种华占（野生型籼稻）稻米中的 Cd 浓度则在 0.33mg/kg 至 2.90mg/kg 之间。特别是，osnramp5 突变体的植株产量没有受到显著影响。此外，我们还开发出了具有极低稻米 Cd 含量的杂交水稻品系。我们的工作为开发 Cd 污染安全的籼稻品种提供了一种实用的方法，最大限度地降低了稻米中 Cd 污染的风险。
