Plants grow towards the light. Their roots grow towards the center of the earth. In addition, there are numerous other processes in plants, for example the formation of leaves, branching or embryonic development. These depend to a large extent on a group of hormones called auxins, which control these processes. In addition to natural auxins, there are numerous synthetic auxins that are also used as herbicides.
Which proteins regulate plant development?
"Numerous transport proteins in plants that can transport auxin across the cell membrane have been known for several decades. These proteins are central to plant development and to many growth processes," says PD Dr. Ulrich Hammes, the study's principal investigator.
A family of auxin exporters called "PIN" proteins, is central to these processes. "The PIN proteins are also interesting candidates for herbicide targets, as we showed last year," says Dorina Janacek, co-author of the study, whose experiments provided important findings for the study.
International collaboration is the key
The group now explains how the transport mechanism works in a collaboration with Prof. Bjørn Pedersen of Denmark's Aarhus University in the current issue of the prestigious journal Nature. "This collaboration between our groups was a key," says Hammes. Prof. Pedersen's group was able to purify the proteins and elucidate their structure.
"We were able to take the purified protein and incorporate it into artificial membranes and then perform functional studies with previously impossible precision," explains Lukas Schulz, a student in the "Molecular Biotechnology" program who played a key role in elucidating the functional mechanism as part of his master's thesis. In elucidating the structure of the protein and its mechanism, a herbicide called naptalam was important.
"It was very interesting and nice to see that the molecule whose function we postulated two years ago does exactly what we thought. However, it is only now that we understand exactly why this is so," says Martina Kolb, who published these results as part of her doctoral thesis two years ago.
Plant growth and development processes are becoming clearer and clearer
Since many processes in plants are controlled by polar auxin transport, the researchers hope that this work will provide them with deeper insights into the exact processes of growth and development.
Another goal with a concrete application is the structure-informed design of environmentally safe herbicides.
Publication:
Ung, K.L., Winkler, M., Schulz, L. et al. Structures and mechanism of the plant PIN-FORMED auxin transporter. Nature (2022). https://doi.org/10.1038/s41586-022-04883-y
Editing:
Dr. Katharina Baumeister
TUM Corporate Communication Center
Press and Public Relations
Scientific contact:
PD Dr. Ulrich Hammes
TUM School of Life Sciences
Chair of Plant Systems Biology
Mail:ulrich.hammes(at)tum.de
Phone: +49 8161.71.2880