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GDP-mannose pyrophosphorylase is a genetic determinant of ammonium sensitivity in Arabidopsis thaliana

By Cheng Qin, Weiqiang Qian, Wenfeng Wang, Yue Wu, Chunmei Yu, Xinhang Jiang, Daowen Wang and Ping Wu


Higher plant species differ widely in their growth responses to ammonium (NH4+). However, the molecular genetic mechanisms underlying NH4+ 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 NH4+. The in planta activities of WT and mutant GMPases all were inhibited by NH4+, 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 NH4+. We conclude that NH4+ inhibits GMPase activity and that the level of GMPase activity regulates Arabidopsis sensitivity to NH4+. 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 NH4+

Topics: Biological Sciences
Publisher: National Academy of Sciences
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Provided by: PubMed Central
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