New insight into iron biogeochemical cycling in soil-rice plant system using iron isotope fractionation  

作　　者：Guojun Chen Tongxu Liu Yongzhu Li Ting Gao Fang Huang Xiaomin Li Songxiong Zhong Fangbai Li 

机构地区：[1]National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China,Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management,Institute of Eco-environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,China [2]State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China [3]CAS Key Laboratory of Crust—Mantle Materials and Environments,School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China [4]SCNU Environmental Research Institute,Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety&MOE Key Laboratory of Theoretical Chemistry of Environment,South China Normal University,Guangzhou 510006,China

出　　处：《Fundamental Research》2021年第3期277-284,共8页自然科学基础研究（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Grant Nos.41807026,42030702,and U20A20109);China Postdoctoral Science Foundation(Grant Nos.2020T130126 and 2019M662820);Guangdong Key Research and Development Project(Grant Nos.2019B110207002);Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(Grant Nos.2017BT01Z176);projects of Science and Technology Development in Guangdong Academy of Sciences(Grant Nos.2020GDASYL-20200104022 and 2019GDASYL-0103054);Guangdong Special Support Plan for High-Level Talents(Grant Nos.2017TX04Z175).

摘　　要：Iron (Fe) migration in soil-plants is a critical part of Fe biogeochemical cycling in the earth surface system. Fe isotope fractionation analysis in the soil-rice system is promising for quantitatively assessing various pathways and clarifying Fe transformation processes. However, the mechanisms of Fe isotope fractionation in the soil-rice system are not well understood. In this study, the Fe isotopic compositions (δ^(56)Fe) of rhizosphere soils, pore water, Fe plaque, and rice plant tissues at the jointing and mature stages of the plants were determined. The rice plants were slightly enriched in heavier δ^(56)Fe by 0.3‰ relative to the soil, and the stele and cortex showed similar δ^(56)Fe values, indicating that the uptake of Fe by rice plants predominantly occurred via Fe(III)-phytosiderophores (Fe(III)-PS) chelation, but not Fe(III) reduction. Additionally, at both the jointing and mature stages, the rice plant tissues showed similar δ^(56)Fe values. However, the Fe isotope fractionation between the roots and stems (Δ56Feroot−stem) was 1.39 ± 0.13‰, which is similar to the previously Ab initio-calculated values between Fe(III)-citrate and Fe(III)- 2-deoxymugineic acid (DMA), indicating that both the phloem and xylem have similar δ^(56)Fe values, and the major Fe-chelating substances in the phloem of the rice plants are Fe(III)-DMA and Fe(II)- Nicotianamine (NA). Therefore, this study demonstrates that Fe isotope fractionation can be used as a signature for interpreting the Fe uptake and translocation mechanism in the soil-rice system.

关 键 词：Fe uptake and transport Rice plants Fe isotope fractionation Stele and cortex Phloem and xylem 

分 类 号：S15[农业科学—土壤学]