A critical role of AMT2;1 in root-to-shoot translocation of ammonium in Arabidopsis

Giehl, Ricardo F.H.; Laginha, Alberto M.; Duan, Fengying; Rentsch, Doris; Yuan, Lixing; von Wirén, Nicolaus (2017). A critical role of AMT2;1 in root-to-shoot translocation of ammonium in Arabidopsis. Molecular Plant, 10(11), pp. 1449-1460. Oxford University Press 10.1016/j.molp.2017.10.001

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Ammonium uptake in plant roots is mediated by AMT/MEP/Rh-type ammonium transporters. Out of five AMTs being expressed in Arabidopsis roots, four AMT1-type transporters contribute to ammonium uptake, whereas no physiological function has so far been assigned to the only homolog belonging to the MEP subfamily, AMT2;1. Based on the observation that under ammonium supply transcript levels of AMT2;1 increased and its promoter activity shifted preferentially to the pericycle, we assessed the contribution of AMT2;1 to xylem loading. When exposed to 15N-labeled ammonium, amt2;1 mutant lines translocated less tracer to the shoots and contained less ammonium in the xylem sap. Moreover, in an amt1;1 amt1;2 amt1;3 amt2;1 quadruple deletion line (qko), co-expression of AMT2;1 with either AMT1;2 or AMT1;3 significantly enhanced 15N translocation to shoots, indicating a cooperative action between AMT2;1 and AMT1 transporters. Under N deficiency proAMT2;1-GFP lines showed enhanced promoter activity predominantly in cortical root cells, which coincided with elevated ammonium influx conferred by AMT2;1 at millimolar substrate concentrations. We conclude that besides contributing moderately to root uptake in the low-affinity range, AMT2;1 functions mainly in root-to-shoot translocation of ammonium. These functions depend on its cell type-specific expression in response to the plant nutritional status and to local ammonium gradients.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Molecular Plant Physiology
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Rentsch, Doris

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

1674-2052

Publisher:

Oxford University Press

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

07 Nov 2017 09:19

Last Modified:

23 Nov 2017 16:37

Publisher DOI:

10.1016/j.molp.2017.10.001

PubMed ID:

29032248

Uncontrolled Keywords:

nitrogen uptake; nitrogen translocation; ammonium assimilation; xylem loading; ammonia transport; ammonium influx; glutamine synthetase

BORIS DOI:

10.7892/boris.106482

URI:

https://boris.unibe.ch/id/eprint/106482

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