Browsing by Subject "Transport"

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Regulation of ammonium transport in Arabidopsis thaliana
(2022) Ganz, Pascal; Ludewig, Uwe
The overarching question of this thesis deals with how plants ensure the selective uptake of ammonium while maintaining ion and pH homeostasis. A key component of this is ammonium transporters (AMTs) with high affinity towards their substrate, which are at the same time part of a multilayered protection system against uncontrolled ammonium influx. Conserved protein sequences inside the transporter were analyzed as well as the regulatory system based on post-translational modification of the transporter.
The AtIREGs - characterization of a new family of metal transporters in Arabidopsis thaliana
(2009) Kirchner, Silvia; von Wirén, Nicolaus
Essential transition metals are required in all plant cells for the activities of numerous metal-dependent enzymes and proteins, but can become toxic when present in excess. For the detoxification of heavy metals and to adjust to changes in micronutrient concentrations in the environment, plants possess a tightly controlled metal homeostasis network. In this regard, transition metal transporters are of central importance. Many metal transporters have already been identified, but a large number of candidates for heavy metal transport proteins still have to be analyzed at the biochemical level and within the plant metal homeostasis network. Based on the description of the animal IREG1 metal transporter as an iron exporter in vertebrates, a phylogenetic analysis of eukaryote and prokaryote sequences with similarity to IREG1 showed three homologous genes in Arabidopsis, which were named AtIREG1, AtIREG2 and AtIREG3. As these AtIREG family members were candidates for yet uncharacterized metal transporters, the main objective of this thesis was to investigate the physiological function of this newly identified transporter family in plants.
The wheat AMT2 (AMmonium Transporter) family, possible functions in ammonium uptake and pathogenic/symbiotic interactions
(2023) Porras‐Murillo, Romano; Zhao, Yufen; Hu, Jinling; Ijato, Toyosi; Retamal, Joseline Palafox; Ludewig, Uwe; Neuhäuser, Benjamin
Ammonium uptake into wheat roots relies primarily on two AMmonium Transporters of subfamily one, while the wheat genome comprises 4 to 6 AMT2 type transporters. Plant AMT2s generally show functions in root‐to‐shoot translocation or pathogenic and symbiotic plant–microorganism interactions. We addressed the activity of TaAMT2s in ammonium transport. Nitrogen‐dependent expression implicated a physiological function in ammonium uptake for TaAMT2;1 and in ammonium distribution for TaAMT2;2‐6.