The ferroxidases LPR1 and LPR2 control iron translocation in the xylem of Arabidopsis plants  

作　　者：Zhong-Rui Xu Mei-Ling Cai Ying Yang Ting-Ting You Jian Feng Ma Peng Wang Fang-Jie Zhao 

机构地区：[1]State Key Laboratory of Crop Genetics and Germplasm Enhancement,College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China [2]Institute of Plant Science and Resources,Okayama University,Chuo 2-20-1,Kurashiki 710-0046,Japan [3]Academy for Advanced Interdisciplinary Studies,Nanjing Agricultural University,Nanjing 210095,China

出　　处：《Molecular Plant》2022年第12期1962-1975,共14页分子植物（英文版）

基　　金：This work was supported by the Natural Science Foundation of Jiangsu Province(grant no.BK20190544);the Natural Science Foundation of China(grant no.41977375);the Fundamental Research Funds for the Central Universities(grant no.KYT201802;KYCXJC2022002).

摘　　要：Iron(Fe)deficiency is common in agricultural crops and affects millions of people worldwide.Translocation of Fe in the xylem is a key step for Fe distribution in plants.The mechanism controlling this process remains largely unknown.Here,we report that two Arabidopsis ferroxidases,LPR1 and LPR2,play a crucial and redundant role in controlling Fe translocation in the xylem.LPR1 and LPR2 are mainly localized in the cell walls of xylem vessels and the surrounding cells in roots,leaves,and stems.Knockout of both LPR1 and LPR2 increased the proportion of Fe(II)in the xylem sap,and caused Fe deposition along the vascular bundles especially in the petioles and main veins of leaves,which was alleviated by blocking blue light.The lpr1 lpr2 double mutant displayed constitutive expression of Fe deficiency response genes and overaccumulation of Fe in the roots and mature leaves under Fe-sufficient supply,but Fe deficiency chlorosis in the new leaves and inflorescences under low Fe supply.Moreover,the lpr1 lpr2 double mutant showed lower Fe concentrations in the xylem and phloem saps,and impaired 57Fe translocation along the xylem.In vitro assays showed that Fe(III)-citrate,the main form of Fe in xylem sap,is easily photoreduced to Fe(II)-citrate,which is unstable and prone to adsorption by cell walls.Taken together,these results indicate that LPR1 and LPR2 are required to oxidize Fe(II)and maintain Fe(III)-citrate stability and mobility during xylem translocation against photoreduction.Our study not only uncovers an essential physiological role of LPR1 and LPR2 but also reveals a new mechanism by which plants maintain Fe mobility during long-distance translocation in the xylem.

关 键 词：IRON xylem translocation ferroxidases LPR1 LPR2 iron redox 

分 类 号：Q94[生物学—植物学]