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Identity and functional characterisation of the transporter supporting the Na+ -dependent high-affinity NO3 - uptake in Zostera marina L.
Rubio, Lourdes; Díaz-García, Jordi; Martín-Pizarro, Carmen; Siverio, José M; Raven, John A; Fernández, José A.
Affiliation
  • Rubio L; Departamento de Botánica y Fisiología Vegetal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain.
  • Díaz-García J; Departamento de Botánica y Fisiología Vegetal, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain.
  • Martín-Pizarro C; Laboratorio de Bioquímica y Biotecnología Vegetal, Departamento de Biología Molecular y Bioquímica, Instituto de Hortofruticultura Subtropical y Mediterránea (IHSM), Facultad de Ciencias, Universidad de Málaga- Consejo Superior de Investigaciones Científicas, Málaga, Spain.
  • Siverio JM; Bioquímica y Biología Molecular, Grupo de Metabolismo del Nitrógeno, Instituto de Tecnologías Biomédicas (ITB), Universidad de La Laguna, La Laguna, Tenerife, Spain.
  • Raven JA; University of Dundee at the JHI, Invergowrie, Dundee, UK.
  • Fernández JA; School of Biological Science, University of Western Australia, Crawley, Western Australia, Australia.
Plant Cell Environ ; 46(9): 2851-2866, 2023 09.
Article in En | MEDLINE | ID: mdl-37403836
ABSTRACT
Zostera marina is a seagrass, a group of angiosperms that evolved from land to live submerged in seawater, an environment of high salinity, alkaline pH and usually very low NO3 - . In 2000, we reported the first physiological evidence for the Na+ -dependent high-affinity NO3 - uptake in this plant. Now, to determine the molecular identity of this process, we searched for NO3 - transporters common to other vascular plants encoded in Z. marina's genome. We cloned two candidates, ZosmaNPF6.3 and ZosmaNRT2 with its partner protein ZosmaNAR2. ZosmaNAR2 expression levels increase up to 4.5-fold in Z. marina leaves under NO3 - -deficiency, while ZosmaNRT2 and ZosmaNPF6.3 expressions were low and unaffected by NO3 - . NO3 - transport capacity, kinetic properties and H+ or Na+ -dependence were examined by heterologous expression in the Hansenula polymorpha high-affinity NO3 - transporter gene disrupted strain (∆ynt1). ZosmaNPF6.3 functions as a H+ -dependent NO3 - transporter, without functionality at alkaline pH and apparent dual kinetics (KM = 11.1 µM at NO3 - concentrations below 50 µM). ZosmaNRT2 transports NO3 - in a H+ -independent but Na+ -dependent manner (KM = 1 mM Na+ ), with low NO3 - affinity (KM = 30 µM). When ZosmaNRT2 and ZosmaNAR2 are co-expressed, a Na+ -dependent high-affinity NO3 - transport occurs (KM = 5.7 µM NO3 - ), mimicking the in vivo value. These results are discussed in the physiological context, providing evidence that ZosmaNRT2 is a Na+ -dependent high-affinity NO3 - transporter, the first of its kind to be functionally characterised in a vascular plant, that requires ZosmaNAR2 to achieve the necessary high-affinity for nitrate uptake from seawater.
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Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Zosteraceae Language: En Journal: Plant Cell Environ Journal subject: BOTANICA Year: 2023 Type: Article Affiliation country: Spain

Full text: 1 Collection: 01-internacional Database: MEDLINE Main subject: Zosteraceae Language: En Journal: Plant Cell Environ Journal subject: BOTANICA Year: 2023 Type: Article Affiliation country: Spain