Tunnermann, Laura
- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
Abstract
Nitrogen (N) is an essential nutrient for plant growth and development. While research has traditionally focused on inorganic N forms, such as nitrate and ammonium, organic N forms, including amino acids, have also been detected in the soil. Notably, plants were shown to take up organic N forms and utilize them as an alternative N source. These findings highlight the significance of organic N nutrition. However, most current knowledge on N uptake mechanisms and N starvation responses is derived from studies on inorganic N. This has left substantial gaps in our understanding of how plants acquire and respond to organic N. The work presented in this thesis addresses some of these gaps by investigating the physiological effects of amino acid nutrition and the molecular regulation of amino acid uptake in Arabidopsis thaliana. The results reveal a distinct organic N-specific root phenotype and show that plants supplied solely with the amino acid glutamine (L-gln) are not N-starved. The second part of the thesis investigates the regulation of the amino acid uptake by focusing on the high-affinity transporter LHT1 (LYSINE HISTIDINE TRANSPORTER 1). Experiments identify the CALCIUM DEPENDENT KINASE1 (CPK1) as an interaction partner of LHT1, suggesting a post-translational regulation of the transporter. Interestingly, uptake assays show that CPK1 negatively influences the amino acid uptake. Further experiments confirmed a negative regulatory effect of CPK1 on LHT1 transport activity. To investigate the role of phosphorylation in regulating LHT1, phospho-mutants of the transporter were generated and analyzed. Two potential phosphorylation sites were identified, with Thr151 being identified as a potential CPK1 target site. This thesis enhances our understanding of how plants respond to organic N and provides deeper insights into amino acid uptake, with a particular focus on the LHT1 transport regulation.
Keywords
Arabidopsis thaliana; organic nitrogen; amino acids; glutamine; root phenotype; amino acid transporter; LHT1; post-translational modification; phosphorylation; CPK1; Arabidopsis thaliana; organiskt kväve; aminosyror; glutamin; rotfenotyp; aminosyratransportör; LHT1; posttranslationell modifiering; fosforylering; CPK1
Published in
Acta Universitatis Agriculturae Sueciae
2025, number: 2025:65
Publisher: Swedish University of Agricultural Sciences
SLU Authors
UKÄ Subject classification
Botany
Molecular Biology
Publication identifier
- DOI: https://doi.org/10.54612/a.4rg1sqql2a
- ISBN: 978-91-8124-049-8
- eISBN: 978-91-8124-095-5
Permanent link to this page (URI)
https://res.slu.se/id/publ/142466