Equilibrative nucleoside transporter 1 (ENT1) is critical for pollen germination and vegetative growth in Arabidopsis

• Published in: Journal of experimental botany Vol. 62; no. 13; pp. 4627 - 4637
• Main Authors: Bernard, Carsten, Traub, Michaela, Kunz, H-Henning, Hach, Stefanie, Trentmann, Oliver, Möhlmann, Torsten
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.01.2011
• Subjects: Adenosine - metabolism; Adenosine Triphosphate - metabolism; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Cell membranes; Cyclic AMP - metabolism; Equilibrative Nucleoside Transport Proteins - genetics; Equilibrative Nucleoside Transport Proteins - metabolism; Equilibrative Nucleoside Transporter 1 - genetics; Equilibrative Nucleoside Transporter 1 - metabolism; Extracellular Space - metabolism; Gene Expression Regulation, Plant; Germination; Germination - physiology; Intracellular Space - metabolism; Models, Biological; Mutation - genetics; Nucleoside transport proteins; Nucleosides; Organ Specificity - genetics; Plants; Pollen; Pollen - anatomy & histology; Pollen - genetics; Pollen - growth & development; Pollen - physiology; Pollen germination; Protein Transport; Purines; RESEARCH PAPER; Research Papers; RNA Interference; RNA, Messenger - genetics; RNA, Messenger - metabolism; Seedlings; Subcellular Fractions - metabolism; Vacuoles; Vacuoles - metabolism; salvage pathway; vacuole; pollen; purine; L; equilibrative nucleoside transporter; pyrimidine
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/err183

ENT1 of Arabidopsis thaliana was the first member of the equilibrative nucleoside transporter (ENT) family to be identified in plants and characterized as a cellular, high-affinity nucleoside importer. Evidence is presented here for a tonoplast localization of ENT1 based on proteome data and Western blot analyses. Increased export of adenosine from reconstituted tonoplast preparations from 35S:ENT1 mutants compared with those from the wild type and ENT1-RNAi mutants support this view. Furthermore, increased vacuolar adenosine and vacuolar 2'3'-cAMP (an intermediate of RNA catabolism) contents in ENT1-RNAi mutants, but decreased contents of these metabolites in 35S:ENT1 over-expresser mutants, were observed. An up-regulation of the salvage pathway was detected in the latter mutants, leading to the conclusion that draining the vacuolar adenosine storage by ENT1 over-expression interferes with cellular nucleotide metabolism. As a consequence of the observed metabolic alterations 35S:ENT1 over-expresser mutants exhibited a smaller phenotypic appearance compared with wild-type plants. In addition, ENT1:RNAi mutants exhibited significantly lower in vitro germination of pollen and contained reduced internal and external ATP levels. This indicates that ENT1-mediated nucleosides, especially adenosine transport, is important for nucleotide metabolism, thus influencing growth and pollen germination.