· Researchers in Freiburg have discovered a mechanism by which plant hormones are specifically regulated to adapt growth to environmental conditions – controlled by the so-called ERAD machinery.

· The study has been published in the journal Science Advances.

· The findings could help make crops more resilient and agriculture more sustainable in the future.

How does a plant manage to quickly adapt its growth to changing environmental conditions? A research team at the University of Freiburg led by plant physiologist Prof. Dr. Jürgen Kleine-Vehn has discovered a previously unknown mechanism for this: a cellular degradation machinery acts in the background like a switch that decides whether the plant hormone auxin is available or not. This mechanism enables the plant to respond to the environment and dynamically regulate its growth, whether it be root growth in the soil or shoot curvature towards the light. The results have been published in the journal Science Advances.

PILS proteins as gatekeepers

At the heart of the newly discovered control mechanism are the so-called PILS proteins. They act like gatekeepers: sometimes they retain auxin inside the cell, sometimes they release it for growth. Which decision is made depends on how many of these proteins are present. The Freiburg researchers have now been able to show that a cellular degradation machinery, known as ERAD machinery, regulates the number of PILS proteins as needed. If auxin is required due to changes in the environment, the gatekeepers are degraded and the plant changes its growth mode. Under stable conditions, however, the proteins remain in place and inhibit the hormone response.

Possible key to sustainable agriculture in the future

“You can think of this mechanism as a molecular switch,” says study leader Kleine-Vehn. “The plant decides whether auxin is effective or not, which thus flexibly adapts its growth to the environment.” The discovery opens up a new perspective on the fine control of plant development. It shows how closely internal control mechanisms and external signals are interlinked.

Seinab Noura, a biologist at the University of Freiburg and first author of the study, also emphasises the significance of the findings: “If we make targeted use of such mechanisms, crops could become more resistant to stress.” In the long term, this knowledge could also help to make plants more robust against climate change, a key factor for sustainable agriculture in the future.

• Original publication: Seinab Noura, Jonathan Ferreira Da Silva Santos, Elena Feraru, Sebastian N.W. Hoernstein, Mugurel I. Feraru, Laura Montero-Morales, Ann-Kathrin Rößling, David Scheuring, Richard Strasser, Pitter F. Huesgen, Sascha Waidmann, Jürgen Kleine-Vehn: ERAD machinery controls the conditional turnover of PIN-LIKES in plants. In: Science Advances. DOI: https://doi.org/10.1126/sciadv.adx5027

• Prof. Dr. Jürgen Kleine-Vehn is Professor of Molecular Plant Physiology at the Faculty of Biology at the University of Freiburg. Since 2024, he has also been spokesperson for the Cluster of Excellence CIBSS – Centre for Integrative Biological Signalling Studies. His research focuses on the molecular cell biology of plants.

• The work was carried out as part of the CIBSS – Centre for Integrative Biological Signalling Studies cluster of excellence at the University of Freiburg and was funded by the German Research Foundation (DFG).