Cadmium induced a non-coding RNA microRNA535 mediates Cd accumulation in rice

• Published in: Journal of environmental sciences (China) 2023-08, Vol.130, p.149-162
• Main Authors: Yue, Erkui, Rong, Fuxi, Liu, Zhen, Ruan, Songlin, Lu, Tao, Qian, Haifeng
• Format: Article
• Language: English
• Subjects: Cadmium - metabolism; Cadmium - toxicity; Cadmium stress; CRISPR/Cas9; Food safety; MicroRNA535; MicroRNAs - metabolism; Oryza - genetics; Oryza - metabolism; Soil; Soil Pollutants - metabolism; Soil Pollutants - toxicity; SQUAMOSA promoter binding-like transcription factors; Stress, Physiological
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2022.10.005

•Knockout of miR535 enhances rice plants tolerance to Cd toxicity.•Knockout of miR535 reduces Cd accumulation in rice plants and brown rice.•Overexpressing miR535 reduces rice plants tolerance to Cd and increases Cd concentration in rice.•Improvement of Cd tolerance and low Cd in brown rice by miR535 knockout depends on mainly regulation of SPL7. Identifying key regulators related to cadmium (Cd) tolerance and accumulation is the main factor for genetic engineering to improve plants for bioremediation and ensure crop food safety. MicroRNAs (miRNAs), as fine-tuning regulators of genes, participate in various abiotic stress processes. MiR535 is an ancient conserved non-coding small RNA in land plants, positively responding to Cd stress. We investigated the effects of knocking out (mir535) and overexpressing miR535 (mir535 and OE535) under Cd stress in rice plants in this study. The mir535 plants showed better Cd tolerance than wild type (WT), whereas the OE535 showed the opposite effect. Cd accumulated approximately 71.9% and 127% in the roots of mir535 and OE535 plants, respectively, compared to WT, after exposure to 2 µmol/L Cd. In brown rice, the total Cd accumulation of OE535 and mir535 was about 78% greater and 35% lower than WT. When growing in 2 mg/kg Cd of soil, the Cd concentration was significantly lower in mir535 and higher in OE535 than in the WT; afterward, we further revealed the most possible target gene SQUAMOSA promoter binding-like transcription factor 7(SPL7) and it negatively regulates Nramp5 expression, which in turn regulates Cd metabolism. Therefore, the CRISPR/Cas9 technology may be a valuable strategy for creating new rice varieties to ensure food safety. [Display omitted]