NEWS As the festive season approaches, evergreen conifers like spruce and pine adorn homes worldwide. But while Christmas trees bring warmth and joy into our lives, they endure some of the harshest conditions on Earth in their natural habitats. Most people take it for granted that they maintain their needles lush and green in freezing winters and blinding sunlight in the boreal forests but now scientists can unwrap the science behind conifers’ winter survival.
Conifers have special strategies to survive the harsh winters in the north.
ImageJohnér Bildbyrå ABThe photosynthetic process of most green plants is highly conserved; it functions overall the same in green algae, tulips and redwood trees. Yet, there are differences and scientists are gradually understanding more about both the differences and commonalities.
Conifers have extraordinary winter survival strategies, some of them were not understood until recently. Scientists from Umeå University have, together with colleagues, summarized recent breakthroughs in an article published in Trends in Plant Science.
One of the two main findings, both of which this group of researchers have contributed to, is that conifers change the structure of their thylakoid membranes – where photosynthesis takes place – making Photosystem I (PSI) and Photosystem II (PSII), which otherwise by large remain separated, come in winter closer to each other and work together in a special way named spill-over.
“This helps them to safely dissipate extra energy and avoid damage from too much sunlight in the cold,” says Stefan Jansson, Professor at Umeå Plant Science Centre at Umeå University.
Others have previously, without understanding the mechanism, named the process ‘Sustained Quenching’ as it could put photosynthesis into a lock down mode for days.
The findings could be used for breeding conifers that are resilient to extreme weather conditions.
ImageStefan Jansson and Pushan BagThe second strategy, operating in parallel to spillover, is that conifers use special routes for moving the electrons in photosynthesis. These paths, known as alternative electron flow, involve flavodiiron proteins and help keep the photosynthesis process balanced. This also prevents the system from becoming overloaded when there's too much light and freezing temperatures.
In addition, the photosynthetic apparatus of conifers differs from that of flowering plants (angiosperms) in a few other ways. They lack, for example, some so-called light-harvesting proteins found in other plants.
“All together this can explain why conifers are the dominant species in boreal forests, thriving where few others can, perhaps at the expense of advantages during less challenging conditions; few conifers, if any, grow where water, nutrients and temperature conditions are all favourable” says Pushan Bag, lead author who during his doctoral studies at Umeå Plant Science Centre studied these phenomena.
Understanding these mechanisms may also aid conservation and help predict forest responses to climate change and may in the longer perspective inform strategies for breeding crops that are resilient to extreme weather conditions.
Co-author Alexander Ivanov adds:
”This paper highlights the intricate adaptations of conifers to extreme winter conditions. By combining structural, molecular, and evolutionary insights, it advances our understanding of how these trees have come to dominate some of the harshest ecosystems on Earth.”
The research, titled "Photosynthetic Advantages of Conifers in the Boreal Forest," is a collaboration among leading institutions in the UK, Canada, Sweden and Bulgaria supported by the EU research programme Horizon 2020 and the Human Frontiers Science Program and other funders. The article was published in Trends in Plant Science in December 2024.
For more information, please contact:
Dr. Pushan Bag, University of Oxford
Email: pushan.bag@biology.ox.ac.uk
Stefan Jansson, professor at the Department of Plant Physiology and Umeå Plant Science Centre, Umeå University
Phone: +46 70 677 23 31
Email: stefan.jansson@umu.se
