TY - JOUR
T1 - NRT1.1-related NH4 + toxicity is associated with a disturbed balance between NH4 + uptake and assimilation
AU - Jian, Shaofen
AU - Liao, Qiong
AU - Song, Haixing
AU - Liu, Qiang
AU - Lepo, Joe Eugene
AU - Guan, Chunyun
AU - ZHANG, Jianhua
AU - Ismail, Abdelbagi M.
AU - Zhang, Zhenhua
N1 - Funding Information:
1This study was supported in part by the National Key R&D Program of China (2017YFD0200103 and 2017YFD0200100), the National Natural Science Foundation of China (31101596 and 31372130), the Hunan Provincial Recruitment Program of Foreign Experts, the National Oilseed Rape Production Technology System of China, the 2011 Plan supported by the Chinese Ministry of Education, the Research and Innovation Project of Postgraduates in Hunan Province (CX2015B242), and the Double First-Class Construction Project of Hunan Agricultural University (kxk201801005). 2Author for contact: [[email protected]]. 3Senior author.
PY - 2018/12
Y1 - 2018/12
N2 - A high concentration of ammonium (NH 4 + ) 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 NH 4 + 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 NH 4 NO 3 and (NH 4 ) 2 SO 4 media to assess the function of NRT1.1 in NH 4 + 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 (NH 4 ) 2 SO 4 medium. Grafting experiments between Col-0 and chl1-5 further confirmed that NH 4 + toxicity is influenced by NRT1.1. In (NH 4 ) 2 SO 4 medium, NRT1.1 induced the expression of NH 4 + transporters, increasing NH 4 + 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 NH 4 + accumulation. By contrast, the NRT1.1 mutants showed reduced NH 4 + accumulation and enhanced NH 4 + 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 (NH 4 ) 2 SO 4 suggests that ethylene is involved in NH 4 + toxicity responses. This study showed that NH 4 + toxicity is related to a nitrate-independent signaling function of NRT1.1 in Arabidopsis, characterized by enhanced NH 4 + accumulation and altered NH 4 + metabolism, which stimulates ethylene synthesis, leading to plant senescence.
AB - A high concentration of ammonium (NH 4 + ) 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 NH 4 + 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 NH 4 NO 3 and (NH 4 ) 2 SO 4 media to assess the function of NRT1.1 in NH 4 + 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 (NH 4 ) 2 SO 4 medium. Grafting experiments between Col-0 and chl1-5 further confirmed that NH 4 + toxicity is influenced by NRT1.1. In (NH 4 ) 2 SO 4 medium, NRT1.1 induced the expression of NH 4 + transporters, increasing NH 4 + 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 NH 4 + accumulation. By contrast, the NRT1.1 mutants showed reduced NH 4 + accumulation and enhanced NH 4 + 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 (NH 4 ) 2 SO 4 suggests that ethylene is involved in NH 4 + toxicity responses. This study showed that NH 4 + toxicity is related to a nitrate-independent signaling function of NRT1.1 in Arabidopsis, characterized by enhanced NH 4 + accumulation and altered NH 4 + metabolism, which stimulates ethylene synthesis, leading to plant senescence.
UR - http://www.scopus.com/inward/record.url?scp=85058463812&partnerID=8YFLogxK
U2 - 10.1104/pp.18.00410
DO - 10.1104/pp.18.00410
M3 - Journal article
C2 - 30337453
AN - SCOPUS:85058463812
SN - 0032-0889
VL - 178
SP - 1473
EP - 1488
JO - Plant Physiology
JF - Plant Physiology
IS - 4
ER -