title: Deciphering the molecular basis of ammonium uptake and transport in maritime pine.
abstract: Ammonium is the predominant form of inorganic nitrogen in the soil of coniferous forests. Despite the ecological and economic importance of conifers, the molecular basis of ammonium uptake and transport in this group of gymnosperms is largely unknown. In this study, we describe the functional characterization of members of the AMT gene family in Pinus pinaster: PpAMT1.1, PpAMT1.2 and PpAMT1.3 (subfamily 1) and PpAMT2.1 and PpAMT2.3 (subfamily 2). Our phylogenetic analysis indicates that in conifers, all members of the AMT1 subfamily evolved from a common ancestor that is evolutionarily related to the ancient PpAMT1.2 gene. Individual AMT genes are developmentally and nutritionally regulated, and their transcripts are specifically distributed in different organs. PpAMT1.3 was predominantly expressed in the roots, particularly during N starvation and mycorrhizal interaction, whereas PpAMT2.3 was preferentially expressed in lateral roots. Immunolocalization studies of roots with varied nitrogen availability revealed that PpAMT1 and PpAMT2 proteins play complementary roles in the uptake of external ammonium. Heterologous expression in yeast and Xenopus oocytes revealed that the AMT genes encode functional transporters with different kinetics and with different capacities for ammonium transport. Our results provide new insights on how nitrogen is acquired and transported in conifers.
authors.affiliation: Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071, Málaga, Spain.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Castro-Rodríguez
authors.affiliation: Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071, Málaga, Spain.
authors.forename: Iman
authors.initials: I
authors.lastname: Assaf-Casals
authors.affiliation: Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071, Málaga, Spain.
authors.forename: Jacob
authors.initials: J
authors.lastname: Pérez-Tienda
authors.affiliation: Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Fan
authors.affiliation: Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071, Málaga, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Avila
authors.affiliation: Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK.
authors.forename: Anthony
authors.initials: A
authors.lastname: Miller
authors.affiliation: Departamento de Biología Molecular y Bioquímica, Instituto Andaluz de Biotecnología, Universidad de Málaga, 29071, Málaga, Spain.
authors.forename: Francisco M
authors.initials: FM
authors.lastname: Cánovas
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D055399:Laccaria / Q000502:physiology; D005810:Multigene Family; D010802:Phylogeny; D028223:Pinus / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D014981:Xenopus
chemical_list: D064751:Ammonium Compounds; D027682:Cation Transport Proteins; D010940:Plant Proteins; C088952:ammonium transporters, plant
keywords: AMT; Pinus pinaster; conifers; nitrogen uptake