Nitrate, ammonium, and potassium sensing and signaling

Ho, Cheng-Hsun; Tsay, Yi-Fang

doi:10.1016/j.pbi.2010.08.005

Cited by 107 publications

(65 citation statements)

References 47 publications

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“…Since MtNPF6.8 does not influence the nitrate uptake at 250 lM of nitrate supply nor the global nitrogen status of the plant, it is possible that the role of MtNPF6.8 in response to nitrate is independent of its nitrate transport function. So, MtNPF6.8 could be a nitrate transceptor, having a nitratetransporter and a nitrate-sensor function (Pellizzaro et al 2014), as found for AtNPF6.3 (Ho et al 2009;Ho and Tsay 2010). In addition, Pellizzaro et al (2014) noticed that the induction of NR1 and NR2 was reduced in npf6.8 mutants by 60%, suggesting the existence of other nitrate sensors in M. truncatula (Fig.…”

Section: Primary Nitrate Responsementioning

confidence: 63%

Nitrate transporters: an overview in legumes

Pellizzaro

Alibert

Planchet

et al. 2017

Planta

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Main conclusion The nitrate transporters, belonging to NPF and NRT2 families, play critical roles in nitrate signaling, root growth and nodule development in legumes.Nitrate plays an essential role during plant development as nutrient and also as signal molecule, in both cases working via the activity of nitrate transporters. To date, few studies on NRT2 or NPF nitrate transporters in legumes have been reported, and most of those concern Lotus japonicus and Medicago truncatula. A molecular characterization led to the identification of 4 putative LjNRT2 and 37 putative LjNPF gene sequences in L. japonicus. In M. truncatula, the NRT2 family is composed of 3 putative members. Using the new genome annotation of M. truncatula (Mt4.0), we identified, for this review, 97 putative MtNPF sequences, including 32 new sequences relative to previous studies. Functional characterization has been published for only two MtNPF genes, encoding nitrate transporters of M. truncatula. Both transporters have a role in root system development via abscisic acid signaling: MtNPF6.8 acts as a nitrate sensor during the cell elongation of the primary root, while MtNPF1.7 contributes to the cellular organization of the root tip and nodule formation. An in silico expression study of MtNPF genes confirmed that NPF genes are expressed in nodules, as previously shown for L. japonicus, suggesting a role for the corresponding proteins in nitrate transport, or signal perception in nodules. This review summarizes our knowledge of legume nitrate transporters and discusses new roles for these proteins based on recent discoveries.

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Section: Primary Nitrate Responsementioning

confidence: 63%

Nitrate transporters: an overview in legumes

Pellizzaro

Alibert

Planchet

et al. 2017

Planta

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“…While the identification of a kinase that directly interacts with ammonium transporters is interesting per se, the fact that this kinase is encoded by CIPK23, a major regulator of root NO 3 2 and K + uptake (Ho et al, 2009;Xu et al, 2006;Tsay et al, 2011;Ho and Tsay, 2010), is intriguing. The uptake of major cations and the two inorganic nitrogen forms is known to be well balanced (Haynes, 1990), but integrators of ion transport to maintain charge balance had not been molecularly identified.…”

Section: Discussionmentioning

confidence: 99%

The Kinase CIPK23 Inhibits Ammonium Transport in Arabidopsis thaliana

2017

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Ion transport in plants is not only strictly regulated on a transcriptional level, but it is also regulated posttranslationally. Enzyme modifications such as phosphorylation provide rapid regulation of many plant ion transporters and channels. Upon exposure to high ammonium concentrations in the rhizosphere, the high-affinity ammonium transporters (AMTs) in Arabidopsis thaliana are efficiently inactivated by phosphorylation to avoid toxic accumulation of cytoplasmic ammonium. External ammonium stimulates the phosphorylation of a conserved threonine in the cytosolic AMT1 C terminus, which allosterically inactivates AMT1 trimers. Using a genetic screen, we found that CALCINEURIN B-LIKE INTERACTING PROTEIN KINASE23 (CIPK23), a kinase that also regulates the most abundant NO 3 2 transporter, NPF6;3, and activates the K + channel AKT1, inhibits ammonium transport and modulates growth sensitivity to ammonium. Loss of CIPK23 increased root NH 4 + uptake after ammonium shock and conferred hypersensitivity to ammonium and to the transport analog methylammonium. CIPK23 interacts with AMT1;1 and AMT1;2 in yeast, oocytes, and in planta. Inactivation of AMT1;2 by direct interaction with CIPK23 requires kinase activity and the calcineurin B-like binding protein CBL1. Since K + , NO 3 2 , and NH 4 + are major ions taken up by plants, CIPK23 appears to occupy a key position in controlling ion balance and ion homeostasis in the plant cell.

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“…26,27 Two of these transporters, AtNPF6.3 and AtNRT2.1, have also been proposed to function as receptors, thus earning the name of "transceptor". [28][29][30][31] The coupling of transport to sensing allows the cell to have an accurate perception of the amount of nitrate it is acquiring; once nitrate enters the cytoplasm, it can either be moved to the vacuole, exported from the cell or rapidly converted to other forms of inorganic nitrogen and subsequently assimilated, making accurate assessment of nitrate pools in the cytoplasm problematic. 20,32 The strongest case can be made for AtNPF6.3 being a transceptor, with a nitrate sensing role that can be uncoupled from transport.…”

Section: Nitrate and Aba In Root Developmentmentioning

confidence: 99%

Environmental nitrate signals through abscisic acid in the root tip

Harris

Ondzighi‐Assoume

2017

Plant Signaling & Behavior

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Roots respond to changes in environmental nitrate with a localized stimulation of ABA levels in the root tip. This rise in ABA levels is due to the action of ER-localized b-GLUCOSIDASE 1, which releases bioactive ABA from the inactive ABA-glucose ester. The slow rise in root tip ABA levels stimulates expression of nitrate metabolic enzymes and simultaneously activates a negative feedback loop involving the protein phosphatase, ABI2, which reduces nitrate influx via the AtNPF6.3 transceptor. The rise in root-tip localized ABA also negatively regulates expression of the SCARECROW transcription factor, thus providing a sensitive mechanism for modulating root growth in response to environmental changes.

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Nitrate, ammonium, and potassium sensing and signaling

Cited by 107 publications

References 47 publications

Nitrate transporters: an overview in legumes

Nitrate transporters: an overview in legumes

The Kinase CIPK23 Inhibits Ammonium Transport in Arabidopsis thaliana

Environmental nitrate signals through abscisic acid in the root tip

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