Feli Strohbach (Christian-Albrechts-Universität zu Kiel)
Feli Strohbach's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Kiel University (CAU) in the year 2025 with the title:
Scrutinizing the Posttranslational Regulation of AOX Isoforms from Zostera marina and Hordeum vulgare
This study sheds new light on the isoform-specific posttranslational regulation of AOX isoforms. The results obtained explain how (Zostera marina) may have adapted to a marine habitat through sequence-specific variations in AOX isoforms.
Increasing levels of atmospheric CO2 emissions intensify severe weather extremes globally, leading to more frequent and intense heatwaves and droughts, as well as changes in precipitation patterns worldwide. Crops that are particularly sensitive to waterlogging and submergence, such as barley (Hordeum vulgare), are affected by these dramatically changing environmental conditions, resulting in severe losses in agricultural yield due to oxygen deprivation. Flooding reduces oxygen levels, leading to oxidative stress in plants, which is caused by increased electron pressure in mitochondrial respiration, among other things. This electron pressure can lead to the formation of harmful reactive oxygen species (ROS). If flooding is followed by a period of reoxygenation, the rapid increase in oxygen leads to an additional increase in ROS accumulation. The alternative oxygenase (AOX) enzyme reduces electron pressure by transferring electrons directly from ubiquitin to oxygen, thereby preventing an increase in intracellular ROS. While the posttranslational regulation of AOX isoforms from Arabidopsis thaliana has been analyzed in detail (Selinski et al., 2016; 2017, and 2018), no studies have investigated posttranslational regulation in species such as barley or the closely related marine species Zostera marina to date.
This study analyzed the posttranslational regulation of AOX isoforms from H. vulgare and Z. marina using heterologous expression in the double mutant E. coli BHH8-pT7pol26, which was established by Selinski et al. (2016), as well as using a Clark-type oxygen electrode. Analysis of the post-translational regulation of AOX isoforms revealed isoform-specific regulations in both species. In addition, species-spanning, sequence-specific properties in posttranslational regulation were demonstrated. These results provide new insights into habitat-specific adaptations in AOX activity regulation. The results obtained in this study provide valuable insights into the adaptation of terrestrial and marine plants to their habitat and can thus be used to increase the stress resistance of valuable crops, such as H. vulgare, to waterlogging and submergence.
--
Selinski J., Hartmann A., Höfler S., Deckers-Hebestreit G., Scheibe R. (2016): Refined method to study the posttranslational regulation of alternative oxidases from Arabidopsis thaliana in vitro. Physiol Plant 157: 264–279
Selinski J., Hartmann A., Kordes A., Deckers-Hebestreit G., Whelan J., Scheibe R. (2017): Analysis of Posttranslational Activation of Alternative Oxidase Isoforms, Plant Physiology, 174, 2113–2127, https://doi.org/10.1104/pp.17.00681
Selinski J., Hartmann A., Deckers-Hebestreit G., Day D. A., Whelan J., Scheibe R. (2018): Alternative Oxidase Isoforms Are Differentially Activated by Tricarboxylic Acid Cycle Intermediates, Plant Physiology, 176, 1423–1432, https://doi.org/10.1104/pp.17.01331
___
Feli Strohbach conducted this work at the department of Plant Cell Biology at the Botanical Institute at CAU Kiel in the working group of Prof. Dr. Jennifer Heiser (formerly Jeniffer Selinski).