Research

Wider research context Polar auxin transport mediated by PIN-FORMED (PIN) proteins is essential for plant development and adaptive root growth. While phosphorylation and ubiquitylation are established regulators of PIN function, recent findings indicate that conserved cysteine residues in PIN proteins undergo additional post-translational modifications (PTMs), including S-acylation, redox-dependent oxidation and potentially S-nitrosylation. Interference with these modifications influences PIN2 membrane distribution, trafficking, and responsiveness to environmental cues, suggesting a previously unrecognized regulatory layer controlling auxin transport. Objectives We hypothesize that reversible cysteine PTMs dynamically regulate PIN trafficking and polarity, and that enzymes such as the acyl protein thioesterase WAVY GROWTH 2 (WAV2) modulate these modifications. Our objectives are to identify cysteine PTMs in Arabidopsis PIN1 and PIN2, determine how they affect sorting and intracellular distribution, and assess their contribution to adaptive root growth responses. Approach The project combines quantitative PTM detection (acyl-RAC, mPEG-switch, biotin-switch), pin1/pin2Cys-Ala mutant variants, and live-cell imaging to define PTM-dependent effects on PIN localization, sorting, and membrane domain partitioning. Environmental and pharmacological perturbations will be used to monitor dynamic PTM changes during tropisms. Moreover, a potential function of WAV2 in controlling the PIN2 S-acylation status will be assessed through genetic interaction analyses, PTM profiling, and subcellular co-localization and interaction assays. Innovation The project introduces cysteine-based PTMs as a so far unknown mechanism in regulating PIN functionality. It integrates lipidation-, S-nitrosylation-, and redox-driven processes with auxin transport control, providing a fundamental, functional analysis of cysteine PTMs in plant intrinsic membrane proteins and establishing WAV2-mediated de-S-acylation as a candidate regulatory mechanism for adaptive root growth. Primary researchers involved The project is led by an expert in PIN trafficking and post-translational regulation, and will serve as a platform for education and training of junior team members in a proliferating field of organismal and molecular biology.

To face environmental stresses, plants rely on cellular adaptation mechanisms to adjust their cellular homeostasis and onset a stress response. This adaptation requires a large proteome remodelling relying on proteolytic pathways to ensure removal of unwanted proteins. Among the environmental perturbations plants face, salinity stress is one of the major threats. Due to its nature, increase in soil salt content leads to strong plant growth inhibition through ionic imbalance, osmotic stress, oxidative stress and reduced nutrient uptake. However, the mechanisms underlying proteome remodelling to mitigate salt stress are poorly understood. This project aims to investigate the importance of plant selective autophagy in response to salt-stress. It will provide significant advances in our understanding of plant response to stress, in an era where agricultural challenges are increasing.

The soybean is a key source of protein for animal feed due to its high protein content. In Austria and across Europe, the cultivation area is increasing, but it still falls significantly short of demand. One obstacle to direct use is trypsin inhibitors (TI), antinutritional proteins that severely impair digestibility—especially in pigs and poultry. Currently, energy- and cost-intensive processes such as toasting or extrusion are required, which also reduce protein quality. Natural variation for breeding-based reduction of TI activity (TIA) is largely lacking. Knocking out individual genes leads to “proteome rebalancing” and the loss of sulfur-containing amino acids, which are essential for feed quality—meaning classical breeding strategies reach their limits here. The project purses two approaches: (1) precise genome editing using CRISPR/Cas to modify Kunitz and Bowman–Birk genes so that the proteins lose their inhibitory effect while retaining sulfur-containing amino acids; and (2) conventional breeding that utilizes genetic diversity to further reduce TIA. The developed lines will be functionally validated and compared with control plants in terms of TIA, protein content, and protein quality. An accompanying socio-economic analysis evaluates the potential and challenges of biotechnological approaches in plant breeding. The project is carried out by a new consortium consisting of BOKU Vienna and Saatzucht Gleisdorf. The close integration of university research and applied breeding ensures that the results can be transferred into practice. The expected outcomes include novel soybean lines with reduced TIA as starting material for variety breeding, as well as fundamental insights into the regulation of TI proteins. This will enable direct, energy-efficient on-farm use, open up new value creation opportunities for agriculture and the feed industry, and sustainably strengthen regional protein production.