PDX1.1-dependent biosynthesis of vitamin B6 protects roots from ammonium-induced oxidative stress  

作　　者：Ying Liu Rodolfo A.Maniero Ricardo F.H.Giehl Michael Melzer Priscille Steensma Gabriel Krouk Teresa B.Fitzpatrick Nicolaus von Wirén 

机构地区：[1]Molecular Plant Nutrition,Leibniz Institute of Plant Genetics and Crop Plant Research(IPK),Corrensstrasse 3,06466 Gatersleben,Germany [2]Structural Cell Biology,Leibniz Institute of Plant Genetics and Crop Plant Research(IPK),Corrensstrasse 3,06466 Gatersleben,Germany [3]Department of Botany and Plant Biology,University of Geneva,1211 Geneva,Switzerland [4]BPMP,Universitéde Montpellier,CNRS,INRA,SupAgro,Montpellier,France [5]State Key Laboratory of Crop Genetics and Germplasm Enhancement,College of Resources and Environmental Sciences,Nanjing Agricultural University,Nanjing 210095,China

出　　处：《Molecular Plant》2022年第5期820-839,共20页分子植物（英文版）

基　　金：Sequence data in this study can be found in The Arabidopsis Information Resource according to the following accession numbers:PDX1.1(AT2G38230);PDX1.2(AT3G16050);PDX1.3(AT5G01410);PDX2(AT5G60540);PDX3(AT5G49970);SOS4(AT5G37850);PLR1(AT5G53580);UBQ10(AT4G05320);ACTIN2(AT3G18780).

摘　　要：Despite serving as a major inorganic nitrogen source for plants,ammonium causes toxicity at elevated con-centrations,inhibiting root elongation early on.While previous studies have shown that ammonium-inhibited root development relates to ammonium uptake and formation of reactive oxygen species(ROS)in roots,it remains unclear about the mechanisms underlying the repression of root growth and how plants cope with this inhibitory effect of ammonium.In this study,we demonstrate that ammonium-induced apo-plastic acidification co-localizes with Fe precipitation and hydrogen peroxide(H_(2)O_(2))accumulation along the stele of the elongation and differentiation zone in root tips,indicating Fe-dependent ROS formation.By screening ammonium sensitivity in T-DNA insertion lines of ammonium-responsive genes,we identified PDX1.1,which is upregulated by ammonium in the root stele and whose product catalyzes de novo biosyn-thesis of vitamin B6.Root growth of pdx1.1 mutants is hypersensitive to ammonium,while chemical complementation or overexpression of PDX1.1 restores root elongation.This salvage strategy requires non-phosphorylated forms of vitamin B6 that are able to quench ROS and rescue root growth from ammo-nium inhibition.Collectively,these results suggest that PDX1.1-mediated synthesis of non-phosphorylated B6 vitamers acts as a primary strategy to protect roots from ammonium-dependent ROS formation.

关 键 词：ammonium nutrition apoplastic pH Fe mobilization root elongation PYRIDOXINE ROS scavenging 

分 类 号：Q94[生物学—植物学]