The ferroxidases LPR1 and LPR2 control iron translocation in the xylem of Arabidopsis plants
作者机构：State Key Laboratory of Crop Genetics and Germplasm EnhancementCollege of Resources and Environmental SciencesNanjing Agricultural UniversityNanjing 210095China Institute of Plant Science and ResourcesOkayama UniversityChuo 2-20-1Kurashiki 710-0046Japan Academy for Advanced Interdisciplinary StudiesNanjing Agricultural UniversityNanjing 210095China
出 版 物：《Molecular Plant》 (分子植物（英文版）)
年 卷 期：2022年第15卷第12期
页 面：1962-1975页
核心收录：
学科分类：0710[理学-生物学] 071001[理学-植物学] 07[理学]
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).
主 题：iron xylem translocation ferroxidases LPR1 LPR2 iron redox
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.
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