Induction of S-nitrosoglutathione reductase protects root growth from ammonium toxicity by regulating potassium homeostasis in Arabidopsis and rice

Induction of GSNOR increases NH4+ tolerance in Arabidopsis roots by counteracting NO-mediated suppression of tissue K+, which depends on VTC1 function. Abstract Ammonium (NH4+) is toxic to root growth in most plants already at moderate levels of supply, but mechanisms of root growth tolerance to NH4...

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Published in:Journal of experimental botany 2021-05, Vol.72 (12), p.4548-4564
Main Authors: Zhang, Lin, Song, Haiyan, Li, Baohai, Wang, Meng, Di, Dongwei, Lin, Xianyong, Kronzucker, Herbert J, Shi, Weiming, Li, Guangjie
Format: Article
Language:English
Subjects:
Aldehyde Oxidoreductases - genetics
Ammonium Compounds
Arabidopsis - genetics
Arabidopsis Proteins
Glutathione Reductase
Homeostasis
Oryza - genetics
Oxidoreductases
Potassium
S-Nitrosoglutathione
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Summary:Induction of GSNOR increases NH4+ tolerance in Arabidopsis roots by counteracting NO-mediated suppression of tissue K+, which depends on VTC1 function. Abstract Ammonium (NH4+) is toxic to root growth in most plants already at moderate levels of supply, but mechanisms of root growth tolerance to NH4+ remain poorly understood. Here, we report that high levels of NH4+ induce nitric oxide (NO) accumulation, while inhibiting potassium (K+) acquisition via SNO1 (sensitive to nitric oxide 1)/SOS4 (salt overly sensitive 4), leading to the arrest of primary root growth. High levels of NH4+ also stimulated the accumulation of GSNOR (S-nitrosoglutathione reductase) in roots. GSNOR overexpression improved root tolerance to NH4+. Loss of GSNOR further induced NO accumulation, increased SNO1/SOS4 activity, and reduced K+ levels in root tissue, enhancing root growth sensitivity to NH4+. Moreover, the GSNOR-like gene, OsGSNOR, is also required for NH4+ tolerance in rice. Immunoblotting showed that the NH4+-induced GSNOR protein accumulation was abolished in the VTC1- (vitamin C1) defective mutant vtc1-1, which is hypersensititive to NH4+ toxicity. GSNOR overexpression enhanced vtc1-1 root tolerance to NH4+. Our findings suggest that induction of GSNOR increases NH4+ tolerance in Arabidopsis roots by counteracting NO-mediated suppression of tissue K+, which depends on VTC1 function.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/erab140