The lives of all plants are controlled by light-sensitive proteins. They measure light and decide when it is time to start flowering or shed their leaves. Chemist Sebastian Westenhoff has studied how this process takes place inside the cells, using advanced techniques.
Last autumn, there was a tree in Slottsskogen that kept its leaves long after all the others had lost theirs. This is because it stands next to a streetlight, and the extra light meant that the tree thought it was still summer, as Sebastian Westenhoff explains.
Sebastian is a researcher in biophysical chemistry at the Department of Chemistry and Molecular Biology, studying the structures and changes of proteins at the most fundamental level of all. He has shown how the lives of plants are controlled by phytochromes. These are light-sensitive proteins found in the leaves of all plants, which measure sunlight.
“Without phytochromes, nothing would grow,” he says.
The light measurement changes the structure of the phytochromes, telling the leaf to drop off as the days grow shorter. And when spring comes again, the plant understands that there is enough light to start flowering. The same phenomenon explains why plants of the same type are often the same height, such as in a field of maize.
“If a maize plant is in the shadow of another plant, it will put a lot of energy into growing to reach the sun. But when it reaches the sun, it stops growing and puts all its energy into producing ears of maize.”
Sebastian made his discovery in partnership with a Finnish researcher. It is based on his own technique for measuring protein structures, a method called time-resolved x-ray scattering. This involves starting a reaction that the protein is involved in and monitoring how the atoms behave using short x-ray pulses from a synchrotron or an x-ray reader.
“This means we can understand how a protein works in the body, in a leaf or in a bacterium.”
The Finnish researcher got in touch a couple of years again and asked if they could try using Sebastian’s technique to study the movements of phytochromes.
“He had the protein and the problem, and I had the technique to solve it.”
In future, knowledge about phytochromes could be used to help develop new cultivation methods for locations with low light levels. And researchers in Berlin are following another track to study phytochromes using optogenetics, which involves using light to control cells in human tissue. It is hoped that this could be used one day to cure certain diseases by attaching a substance in a particular part of the body and shining ordinary light on it.
Sebastian’s research also includes a completely different side line. He is currently working with game developers to create a computer game. He wants to use young people’s passion for computer games to interest them in science.
“It’s such a shame that interest in science is declining. We need to do something about it. Hopefully, young people will start playing and discover that it’s not boring – it’s actually incredibly interesting.”
Sebastian has featured on adverts on Gothenburg’s trams, encouraging young people to study science. He wants to convey his passion and what drives him: his curiosity about the most fundamental processes of all.
“I want to understand how things work at atomic level.”