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Distinct signalling pathways and transcriptome response signatures differentiate ammonium‐ and nitrate‐supplied plants
Author(s) -
PATTERSON KURT,
CAKMAK TURGAY,
COOPER ANDREW,
LAGER IDA,
RASMUSSON ALLAN G.,
ESCOBAR MATTHEW A.
Publication year - 2010
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2010.02158.x
Subject(s) - ammonium , nitrate , ammonium nitrate , chemistry , nitrogen cycle , transcriptome , biochemistry , nitrogen , nitrogen deficiency , biology , botany , gene expression , gene , organic chemistry
Nitrogen is the only macronutrient that is commonly available to plants in both oxidized and reduced forms, mainly nitrate and ammonium. The physiological and molecular effects of nitrate supply have been well studied, but comparatively little is known about ammonium nutrition and its differential effects on cell function and gene expression. We have used a physiologically realistic hydroponic growth system to compare the transcriptomes and redox status of the roots of ammonium‐ and nitrate‐supplied Arabidopsis thaliana plants. While ∼60% of nitrogen‐regulated genes displayed common responses to both ammonium and nitrate, significant ‘nitrate‐specific’ and ‘ammonium‐specific’ gene sets were identified. Pathways involved in cytokinin response and reductant generation/distribution were specifically altered by nitrate, while a complex biotic stress response and changes in nodulin gene expression were characteristic of ammonium‐supplied plants. Nitrate supply was associated with a rapid decrease in H 2 O 2 production, potentially because of an increased export of reductant from the mitochondrial matrix. The underlying basis of the nitrate‐ and ammonium‐specific patterns of gene expression appears to be different signals elaborated from each nitrogen source, including alterations in extracellular pH that are associated with ammonium uptake, downstream metabolites in the ammonium assimilation pathway, and the presence or absence of the nitrate ion.