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Journal article
NRT1.1-Related NH4+ Toxicity Is Associated with a Disturbed Balance between NH4+ Uptake and Assimilation
Plant physiology (Bethesda), Vol.178(4), pp.1473-1488
12/01/2018
PMID: 30337453
Web of Science ID: WOS:000452471800008
Abstract
A high concentration of ammonium (NH4+) as the sole source of nitrogen in the growth medium often is toxic to plants. The nitrate transporter NRT1.1 is involved in mediating the effects of NH4+ toxicity; however, the mechanism remains undefined. In this study, wild-type Arabidopsis (Arabidopsis thaliana Columbia-0 [Col-0]) and NRT1.1 mutants (chl1-1 and chl1-5) were grown hydroponically in NH4NO3 and (NH4)(2)SO4 media to assess the function of NRT1.1 in NH4+ stress responses. All the plants grew normally in medium containing mixed nitrogen sources, but Col-0 displayed more chlorosis and lower biomass and photosynthesis than the NRT1.1 mutants in (NH4)(2)SO4 medium. Grafting experiments between Col-0 and chli-5 further confirmed that NH4+ toxicity is influenced by NRT1.1. In (NHASO, medium, NRT1.1 induced the expression of NH4+ transporters, increasing NH4+ uptake. Additionally, the activities of glutamine synthetase and glutamate synthetase in roots of Col-0 plants decreased and soluble sugar accumulated significantly, whereas pyruvate kinase-mediated glycolysis was not affected, all of which contributed to NH4+ accumulation. By contrast, the NRT1.1 mutants showed reduced NH4+ accumulation and enhanced NH4+ assimilation through glutamine synthetase, glutamate synthetase, and glutamate dehydrogenase. Moreover, the up-regulation of genes involved in ethylene synthesis and senescence in Col-0 plants treated with (NH4)(2)SO4 suggests that ethylene is involved in NH4+ toxicity responses. This study showed that NH4+ toxicity is related to a nitrate-independent signaling function of NRT1.1 in Arabidopsis, characterized by enhanced NH4+ accumulation and altered NH4+ metabolism, which stimulates ethylene synthesis, leading to plant senescence.
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Details
- Title
- NRT1.1-Related NH4+ Toxicity Is Associated with a Disturbed Balance between NH4+ Uptake and Assimilation
- Publication Details
- Plant physiology (Bethesda), Vol.178(4), pp.1473-1488
- Resource Type
- Journal article
- Publisher
- Oxford University Press
- Number of pages
- 16
- Grant note
- 2017YFD0200103; 2017YFD0200100 / National Key R&D Program of China kxk201801005 / Double First-Class Construction Project of Hunan Agricultural University National Oilseed Rape Production Technology System of China Hunan Provincial Recruitment Program of Foreign Experts CX2015B242 / Research and Innovation Project of Postgraduates in Hunan Province 31101596; 31372130 / National Natural Science Foundation of China; National Natural Science Foundation of China (NSFC) Chinese Ministry of Education; Ministry of Education, China
- Copyright
- © 2018 American Society of Plant Biologists. All rights reserved.
- Identifiers
- WOS:000452471800008; 99380624989006600
- Academic Unit
- Biology; Center for Environmental Diagnostics and Bioremediation ; Hal Marcus College of Science and Engineering
- Language
- English