Rice (Oryza sativa L.) seedlings enriched with zinc or manganese: Their impacts on cadmium accumulation and expression of related genes

• Published in: Pedosphere Vol. 31; no. 6; pp. 849 - 858
• Main Authors: HUANG, Gaoxiang, DING, Changfeng, MA, Yibing, WANG, Yurong, ZHOU, Zhigao, ZHENG, Shun’an, WANG, Xingxiang
• Format: Journal Article
• Language: English
• Published: Beijing Elsevier Ltd 01.12.2021; Elsevier Science Ltd; Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008(China); University of Chinese Academy of Sciences,Beijing 100049(China)%Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008(China); Ecological Experimental Station of Red Soil,Chinese Academy of Sciences,Yingtan 335211(China); University of Chinese Academy of Sciences,Beijing 100049(China)%Macau Environmental Research Institute,Macau University of Science and Technology,Taipa 999078,Macau(China)%Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008(China)%Rural Energy and Environment Agency,Ministry of Agriculture and Rural Affairs,Beijing 100125(China)%Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008(China); University of Chinese Academy of Sciences,Beijing 100049(China); School of Geography and Environment,Key Laboratory of Poyang Lake Wetland and Watershed Research,Ministry of Education,Jiangxi Normal University,Nanchang 330022(China)
• Subjects: absorption enrichment; Accumulation; Aquatic plants; Cadmium; Cd contamination; contaminated paddy soil; Field tests; Food contamination; Food safety; Gene expression; Hydroponics; Manganese; Oryza sativa; Rice; Rice fields; Roots; Sediment pollution; Seedlings; Shoots; Soil contamination; Soil pollution; Soils; Translocation; translocation factor; Transport properties; Zinc; Zinc sulfate; hydroponics; Cd contamination; translocation factor; gene expression; contaminated paddy soil; absorption enrichment
• ISSN: 1002-0160; 2210-5107
• DOI: 10.1016/S1002-0160(20)60047-9

Cadmium (Cd) contamination in paddy soils means that the rice produced there may be unsafe for human consumption. A hydroponic study was conducted to enrich rice seedlings with zinc (Zn) or manganese (Mn), and the uptake and transport characteristics of Cd in these Zn- and Mn-rich seedlings were subsequently investigated using a greenhouse pot trial. The results showed that hydroponic cultivation in 10–50 µmol L–1 Zn (ZnSO4·7H2O) or 50–250 µmol L–1 Mn (MnSO4·H2O) for 30 d had no significant impact on rice growth, while the accumulation of Zn and Mn was 7.31–18.5 and 25.4–47.7 times higher, respectively, than in the control (no Zn or Mn addition). The accumulation of Cd in the Zn- and Mn-rich rice plants was 26.3%–38.6% and 34.4%–44.5% lower than that in the control, respectively, and the translocation factors of Cd from roots to shoots also decreased by 23.3%–41.3% and 25.3%–37.0%, respectively, after transplanting to Cd-contaminated soils. Furthermore, the relative expression levels of OsIRT1 (Oryza sativa iron-regulated transporter 1) were downregulated by 40.1%–59.3% and 16.0%–25.9%, respectively, in the Zn- and Mn-rich seedling roots. This downregulation may indicate a possible mechanism contributing to the reductions in Cd absorption. Field experiments confirmed that the Zn- and Mn-rich seedlings produced brown rice (unpolished rice grains) with significantly decreased concentrations of Cd (34.2%–44.4%). This study provides an innovative method for reducing the food safety risks from rice grown on slightly to moderately Cd-contaminated paddy soils.