title: GDP-mannose pyrophosphorylase is a genetic determinant of ammonium sensitivity in Arabidopsis thaliana.
abstract: Higher plant species differ widely in their growth responses to ammonium (NH(4)(+)). However, the molecular genetic mechanisms underlying NH(4)(+) sensitivity in plants remain unknown. Here, we report that mutations in the Arabidopsis gene encoding GDP-mannose pyrophosphorylase (GMPase) essential for synthesizing GDP-mannose confer hypersensitivity to NH(4)(+). The in planta activities of WT and mutant GMPases all were inhibited by NH(4)(+), but the magnitude of the inhibition was significantly larger in the mutant. Despite the involvement of GDP-mannose in both l-ascorbic acid (AsA) and N-glycoprotein biosynthesis, defective protein glycosylation in the roots, rather than decreased AsA content, was linked to the hypersensitivity of GMPase mutants to NH(4)(+). We conclude that NH(4)(+) inhibits GMPase activity and that the level of GMPase activity regulates Arabidopsis sensitivity to NH(4)(+). Further analysis showed that defective N-glycosylation of proteins, unfolded protein response, and cell death in the roots are likely important downstream molecular events involved in the growth inhibition of Arabidopsis by NH(4)(+).
authors.affiliation: The State Key Laboratory of Plant Physiology and Biochemistry, College of Life Science, Zhejiang University, Hangzhou 310058, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Qin
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Qian
authors.forename: Wenfeng
authors.initials: W
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Wu
authors.forename: Chunmei
authors.initials: C
authors.lastname: Yu
authors.forename: Xinhang
authors.initials: X
authors.lastname: Jiang
authors.forename: Daowen
authors.initials: D
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D005816:Genetic Complementation Test; D006031:Glycosylation; D009154:Mutation; D009713:Nucleotidyltransferases / Q000378:metabolism*; D010940:Plant Proteins / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D000644:Quaternary Ammonium Compounds / Q000633:toxicity*
chemical_list: D017931:DNA Primers; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase