Galactosylation of rhamnogalacturonan-Ⅱ for cell wall pectin biosynthesis is critical for root apoplastic iron reallocation in Arabidopsis  

作　　者：Jia-Shi Peng Bao-Cai Zhang Hao Chen Meng-Qi Wang Ya-Ting Wang Hong-Mei Li Shao-Xue Cao Hong-Ying Yi Hang Wang Yi-Hua Zhou Ji-Ming Gong 

机构地区：[1]National Key Laboratory of Plant Molecular Genetics,CAS Center for Excellence in Molecular Plant Sciences,Institute of Plant Physiology and Ecology,Chinese Academy of Sciences,Shanghai 200032,China [2]State Key Laboratory of Plant Genomics,Institute of Genetics and Developmental Biology,Innovation Academy for Seed Design,Chinese Academy of Sciences,Beijing 100101,China [3]Hunan Key Laboratory of Economic Crops Genetic Improvement and Integrated Utilization,School of Life Science,Hunan University of Science and Technology,Xiangtan 411201,China [4]University of Chinese Academy of Sciences,Beijing 100049,China [5]School of Life Science and Technology,Shanghai Tech University,Shanghai 201210,China

出　　处：《Molecular Plant》2021年第10期1640-1651,共12页分子植物（英文版）

基　　金：This research was supported by the XDB27020101 of Chinese Academy of Sciences;the National Natural Science Foundation of China(31325003,31530051,and 31700212);the National Key Laboratory of Plant Molecular Genetics.

摘　　要：Apoplastic iron(Fe)in roots represents an essential Fe storage pool.Reallocation of apoplastic Fe is of great importance to plants experiencing Fe deprivation,but how this reallocation process is regulated remains elusive,likely because of the highly complex cell wall structure and the limited knowledge about cell wall biosynthesis and modulation.Here,we present genetic and biochemical evidence to demonstrate that the Cdi-mediated galactosylation of rhamnogalacturonan-II(RG-II)is required for apoplastic Fe reallocation.Cdi is expressed in roots and up-regulated in response to Fe deficiency.It encodes a putative glycosyltransferase localized to the Golgi apparatus.Biochemical and mass spectrometry assays showed that Cdi catalyzes the transfer of GDP-L-galactose to the terminus of side chain A on RG-II.Disruption of Cdi essentially decreased RG-II dimerization and hence disrupted cell wall formation,as well as the reallocation of apoplastic Fe from roots to shoots.Further transcriptomic,Fourier transform infrared spectroscopy,and Fe desorption kinetic analyses coincidently suggested that Cdi mediates apoplastic Fe reallocation through extensive modulation of cell wall components and consequently the Fe adsorption capacity of the cell wall.Our study provides direct evidence demonstrating a link between cell wall biosynthesis and apoplastic Fe reallocation,thus indicating that the structure of the cell wall is important for efficient usage of the cell wall Fe pool.

关 键 词：Fe reallocation PECTIN GALACTOSYLTRANSFERASE Cdi 

分 类 号：Q94[生物学—植物学]