[2020-12-15] How can conifers that are used for example as Christmas trees keep their green needles over the boreal winter when most trees shed their leaves? Science has not provided a good answer to this question but now an international team of scientists, including researchers from Umeå University, has deciphered that a short-cut in the photosynthetic machinery allows the needles of pine trees to stay green. The study was published today in the journal Nature Communications.
In winter, light energy is absorbed by the green chlorophyll molecules but cannot be utilized by the downstream reactions in the photosynthetic machinery as freezing temperatures stop most biochemical reactions. This is especially a problem in the early spring when temperatures can still be very low, but sunlight is already strong, and the excess light energy can damage the proteins of the photosynthetic machinery. The researchers showed that the photosynthetic apparatus is wired in a special way which allows pine needles to stay green all year long.
Under normal conditions, the two photosystems, the two functional units where light energy is absorbed and converted into chemical energy, are kept apart from each other to prevent a short-cut and allow efficient photosynthesis. In winter, the structure of the thylakoid membrane, where the two photosystems are located, is reorganized which brings the two photosystems in physical contact. The researchers showed that photosystem II donates energy directly to photosystem I and this short-cut mode protects the green chlorophyll and the needles when conditions become harsh.
“We have followed several pine trees growing in Umeå in northern Sweden over three seasons”, says Pushan Bag, PhD student at Umeå university, who has collected samples all around the year and made many of the analyses. “It was essential that we could work on needles “straight from outdoors” to prevent that they adjusted to the higher temperatures in the lab environment before we analysed them for example with electron microscopy which we used to visualize the structure of the thylakoid membrane.”
All plants have safety valves to deal with the excess light energy which is either dissipated as heat or as fluorescence light. However, only conifers seem to have such powerful valves that they can keep the photosynthetic apparatus intact over the extreme boreal winter. The research team combined biochemistry and ultrafast fluorescence analysis, a very sophisticated method that can resolve chlorophyll fluorescence light at a picosecond time scale. Like this, they could demonstrate how the pine needles deal with excess light energy to protect their sensitive photosynthetic apparatus from damage.
“We needed to adjust the equipment to study pine needles in cold temperatures in order to trap the unique mechanism”, explains Volha Chukhutsina from Vrije Universiteit Amsterdam, who has performed much of the ultrafast fluorescence analysis. “We also tried spruce needles but they were hard to fit in a good way into the equipment”. Alfred Holzwarth, who has developed the time-resolved fluorescence measurements adds: “The pine needles gave us the opportunity to study this shortcut mechanism - also called spill-over - as they really show an extreme adaptation.”
The study was done with pine trees, but the researchers believe that the mechanism is probably similar for other conifer species – like the typical Christmas trees spruces and firs - because their photosynthetic apparatus is similar. “This remarkable adaptation not only enjoys us during Christmas but is in fact extremely important for mankind”, says Stefan Jansson from Umeå university. “Hadn´t conifers been able to survive in extreme harsh winter climates vast areas in the northern hemisphere may not have been colonized as conifers provided firewood, housing and other necessities. Still today they form the basis of the economy in most of the circumpolar taiga region”.
About the article:
Bag P., Chukhutsina V., Zhang Z., Paul S., Ivanov A.G., Shutova T., Croce R., Holzwarth A.R., Jansson S. (2020) Direct energy transfer from photosystem II to photosystem I confers winter sustainability in Scots Pine. DOI: 10.1038/s41467-020-20137-9
https://www.nature.com/articles/s41467-020-20137-9
For more information, please contact:
Professor Stefan Jansson
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
Phone +46-70-6772331
Text: Stefan Jansson & Pushan Bag
[2020-12-14] Ioanna Antoniadi is awarded with the UPSC Agrisera Prize 2020 to acknowledge her scientific achievements and her engagement to improve the work environment at UPSC. The UPSC Agrisera Prize is awarded every year to a person working at UPSC and was announced today during the virtual UPSC Christmas Celebration.
Ioanna Antoniadi works as a postdoc in Karin Ljung’s group at the Department of Forest Genetics and Plant Physiology at SLU. Since she started at UPSC, she contributed to several scientific publications, among others to a publication in Nature Communications in 2020. She is the expert for fluorescent-activated cell sorting (FACS) at UPSC - an advanced technique that allows to separate cells according to certain physical characteristics like for example different cell size – and was co-applicant for a successful grant application that allowed to purchase a new FACS instrument recently.
Besides her scientific contribution and her responsibility for supervising and training new users to the FACS instrument, Ioanna Antoniadi is part of the Departmental Common Laboratory Resources group that manages the laboratories at the Department of Forest Genetics and Plant Physiology. The nomination letter pointed out that “she is very engaged in improving the lab environment to make it work at its best” and that she spontaneously took over additional tasks besides her daily responsibilities to improve the work environment at UPSC.
The UPSC Agrisera Prize is awarded every year to a PhD student, a postdoc or a technician for excellent scientific achievement and great commitment to improve the UPSC work environment. It is sponsored by Agrisera but the members of the UPSC board select the winner of the prize. Everyone working at UPSC can nominate a colleague for the UPSC Agrisera Prize. This year, the UPSC Board received nine nominations, the highest number of nominations since 2014.
“The prize gives us the possibility to acknowledge great achievements and commitments and it is every year very difficult to choose one candidate out of many good suggestions”, says Catherine Bellini, chairmen of the UPSC Board who announced the winner of the prize today together with Joanna Porankiewicz-Asplund from Agrisera. “We were delight that we received this high number of nominations this year. It shows that people care about their workplace.”
[2020-12-11] Lignin is the compound that makes plant cell walls waterproof and rigid. This allows plants to stand upright and transport water within their stem. Bernadette Sztojka, PhD student in Hannele Tuominen’s group, studied how lignin is synthesised and deposited in the cell walls, a process called lignification. She showed that cooperation between neighbouring cells is important for lignification of water-transporting vessel elements and identified three new regulators involved in this process. Bernadette Sztojka successfully defended her PhD thesis at Umeå University yesterday.
You did already your master thesis at UPSC but on a different topic. Why did you choose to switch topic and study lignification during your PhD thesis?
The projects I worked on before in the group of Rishikesh Bhalerao were more cell biology-oriented, related to vesicular trafficking. That was already quite a shift because my original background is horticulture. For my PhD, I wanted to further explore new territories this is why I applied for this PhD position, focusing on cell wall and wood formation.
You identified and characterised three new regulators involved in lignification. What do these regulators have in common and why are they peculiar?
The first regulator that we chose to work on was PIRIN2. A gene which is closely related to PIRIN2 was identified earlier in a cell culture system and shown to play a potential role in lignification. That is why we decided to characterise this gene in Arabidopsis. To better understand the molecular function of PIRIN2, we looked for proteins that interact with PIRIN2. That is how we came across the other two molecular players we studied, and this allowed us to expand the known molecular network. One of these two proteins has the opposite effect on lignin biosynthesis than PIRIN2. While PIRIN2 is suppressing the synthesis of certain types of monolignols, which are the basic modules of lignin, this protein is promoting it. The other protein we identified has no direct effect on lignin content or composition but connects lignin biosynthesis to diurnal timing.
Why does lignin biosynthesis need diurnal timing?
There have been a few previous studies that suggested that lignin-biosynthetic genes are activated in a diurnal pattern but there was never any upstream regulator found that controls these genes. Lignin is a very big carbon sink that means that a lot of carbon is required for its biosynthesis. That is why lignin biosynthesis has to be coordinated with resource availability and that brings in the diurnal regulation to connect lignin biosynthesis with carbon fixation during photosynthesis.
Which of your results is the most fascinating for you?
For me the first project, characterizing PIRIN2 and the non-cellautonomous lignification, was the most fascinating. PIRIN2 is a negative regulator of lignification but in a cell-type specific way. It is affecting the lignin composition of the cell walls of its neighbouring cells where it is not expressed. It is located in cells next to xylem vessels which form the water transporting “pipes”. We believe that the vessels need a specific lignin composition to allow for efficient water transport and PIRIN2 makes sure that they acquire the correct composition by suppressing the biosynthesis of certain monolignols which may not be optimal for water transport. I find these types of cooperative processes between cells really fascinating.
What was the biggest challenge you faced during your PhD?
It was hard sometimes to give up on ideas. We might have had a hypothesis and not necessarily showed that the hypothesis was proven right or wrong, but we realized that we did not had the means or time to follow up on this hypothesis. My original project that made me interested in the PhD topic became a bit squeezed in time because some other projects which I was supposed to finish quickly took over like for example the PIRIN2 project. It worked out fine for me in the end, but sometimes it was challenging to accept that I had to let a part of my project go unfinished.
Do you think your results might lead to practical applications in future?
I think especially PIRIN2 could be interesting for the forest industry. By manipulating PIRIN2 it might be possible to generate woody biomass with different lignin composition. Plants often get really sick when the lignin content is modified genetically but this is not the case when PIRIN2 is mutated. The effect on the chemical composition is not very strong in PIRIN2 mutants but those changes can still be beneficial for industrial use and they do not compromise the plant’s fitness.
What are your plans for the future? Do you want to continue with research?
I would like to transition towards more applied research, combining my background in horticulture with my PhD experience in plant molecular biology. This could be either in academia or industry. I am still curious to explore new territories and would like to change a bit the subject again.
About the public defence:
The public defence took place on Thursday, 10th of December at Umeå University. Faculty opponent was Simon Hawkins from the Department of Biology, University of Lille, France. Bernadette Sztojka's supervisor was Hannele Tuominen. The dissertation was live broadcasted via Zoom.
Title of the thesis: New regulators of xylem lignification in Arabidopsis
Link to the thesis: http://umu.diva-portal.org/smash/record.jsf?pid=diva2%3A1500629
For more information, please contact:
Bernadette Sztojka
Department of Plant Physiology
Umeå Plant Science Centre
Umeå University
Email:
[2020-12-08] Stefan Jansson and Ove Nilsson were interviewed by the Swedish TV about CRISPR/CAS9, the technique for which discovery Emmanuelle Charpentier and Jennifer A. Doudna received the Nobel Prize in Chemistry this year. Several reports are broadcasted this week by the Swedish TV to highlight this year’s Nobel Prizes which are officially celebrated on Thursday, the 10th of December. The interviews with the two researchers from UPSC were broadcasted yesterday in “Vetenskapens värld” on Swedish Television (SVT) and in the news on TV4.
CRISPR/CAS9 is already now broadly used in plant research and also at UPSC several plants have been already genetically modified using this technique. This is presented in the reports done by the Swedish TV channels. In “Vetenskapens värld”, a popular science programme on SVT, Stefan Jansson explains how he uses CRISPR/CAS9 in his research and in TV4 News, Ove Nilsson presents the phenotyping platform at UPSC and describes the advantages of CRISPR/CAS9 for plant research. The two reports are online available and contain also a lot of footage from the plant material at UPSC.
Links to the video clips (both in Swedish):
“Vetenskapens värld” on SVT
Footage from UPSC is shown between minute 05:12 and 06:37 and between 10:02 and 10:24
https://www.svtplay.se/video/29350256/vetenskapens-varld/vetenskapens-varld-sasong-33-nobelpristagarna-2020?position=1765&id=e4zWnox
TV4 News from the 7th of December at 22:00 o’clock
Footage from UPSC is shown between minute 18:46 and 21:21
https://www.tv4play.se/program/nyheterna/13308076
On Wednesday last week, Clarivate published its annual list of Highly Cited Researchers 2020. Karin Ljung and Ondřej Novák are again under the top one percent of the world’s most highly cited researchers in the field of “Plant & Animal Science”. This is the third time that Ondřej Novák is on Clarivate’s list and the seventh time for Karin Ljung.
The methodology behind Clarivate’s list is based on citation analyses that determines the top one percent of Highly Cited Researchers using the Web of Science database. More than 6,000 researchers, in 21 fields of the sciences and social sciences, and cross field categories were selected based on the number of highly cited papers they produced over an 11-year period from January 2009 to December 2019.
More information and the full list of Highly Cited Researchers can be found here:
https://recognition.webofscience.com/awards/highly-cited/2020/
Twelve PhD students presented their research projects with short pre-recorded video pitches during the KBC DAYS 2020 last week. The video pitches were the outcome of a course in science communication that the students participated in before. An evaluation committee evaluated all pitches and awarded Lill Eilertsen, PhD student in Judith Lundberg-Felten’s group at UPSC, with the prize for the best presentation.
Every year, the best PhD student presentation is awarded during the KBC DAYS but normally they are presenting their research with a scientific poster. Due to the online format of the KBC DAYS 2020, the organisation committee decided against a poster presentation but instead asked for short pre-recorded video pitches and offered in combination with this a course in science communication. Twelve PhD students affiliated with KBC took the chance and participated in the course. Their video-pitches were evaluated during the KBC DAYS by an evaluation committee of six people and the best presentation was awarded with a travel voucher sponsored by Agrisera AB.
On Thursday last week, the Swedish Research Council announced which project proposals in the field of natural and engineering sciences receive financial support in 2020. Five projects from UPSC were approved. Stéphane Verger receives a starting grant and Rishikesh Bhalerao, Stéphanie Robert, Åsa Strand and Hannele Tuominen project grants.
The topics of the five projects from UPSC deal with seasonal growth, cell shape, cell internal communication, lignin biosynthesis and cell-to-cell adhesion. The focus is for all on the molecular level but using different plant model organisms and applying a wide range of different methods. In total, the Swedish Research Council approved this year 324 of 1668 applications in the field of natural and engineering sciences including research project grants and starting grants.
More information about the individual approved projects:
Project: Unravelling the genetic network mediating temperature control of dormancy release and bud break in hybrid aspen
Bud break in perennial trees starts in spring after trees have been exposed to extended period of cold temperatures that release dormancy, followed by a period of increasing temperatures that signal spring onset. The exact timing of bud break is very crucial for the trees to prevent damage to young leaves and meristems enclosed in the buds from sudden late frosts. Rishikesh Bhalerao is researching on how temperature regulates the release of the dormant state to allow bud break in spring. In the approved project, he plans to identify the genetic framework that controls these temperature-mediated processes in the model tree hybrid aspen.
Contact:
Rishikesh Bhalerao
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences
Email:
https://www.upsc.se/rishikesh_bhalerao
Project: Molecular mechanisms regulating shape acquisition in plants
How does a cell receive its final shape? Stéphanie Robert wants to answer this question focusing on leaf epidermal pavement cells. These cells form the outer layer of the leaf and have a very specific jigsaw puzzle shape. The mechanical and chemical properties of the cell wall but also cell internal factors like the plant growth regulator auxin determine the final shape of a cell. In her project, Stéphanie Robert aims at finding new molecular players involved in the development of cell shape and at looking deeper into the interactions between the different factors involved in this development.
Contact:
Stéphanie Robert
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences
Email:
http://www.upsc.se/stephanie_robert
Project: Establishment of Photosynthesis, a Tale of Two Genomes
Åsa Strand focusses in her project on cell internal communication, specifically on the communication between the chloroplast and the nucleus. The chloroplast is the place were photosynthesis is conducted. Some of the genetic information that is needed for chloroplast development is stored in the nucleus. That is why a synchronised exchange of information between the chloroplast and the nucleus is indispensable for proper chloroplast development. Åsa Strand wants to understand in more detail how this communication between the chloroplast and the nucleus is regulated.
Contact:
Åsa Strand
Department of Plant Physiology
Umeå Plant Science Centre
Umeå University
Email:
http://www.upsc.se/asa_strand
Project: Cell-type specific lignification in plant vasculature
Lignin is used by plants to increase stability and provide a water repellent surface in the water transporting system. However, for industrial applications, it often reduces the accessibility of the favoured cellulose. Hannele Tuominen aims on identifying the molecular mechanisms behind lignin biosynthesis and on characterising lignin composition in different cell types. To understand how and why cell-type specific lignification is established might help to improve the properties of lignocellulosic raw material for bioprocessing.
Contact:
Hannele Tuominen
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences
Email:
http://www.upsc.se/hannele_tuominen
Project: Mechanics and dynamics of cell-to-cell adhesion in plants
Stéphane Verger focusses in his research on how neighbouring cells in a tissue interact and attach to each other, a dynamic process called cell adhesion. To maintain cell adhesion despite changes in the surrounding is very important to keep a tissue functioning and Stéphane Verger wants to reveal the dynamic mechanisms that are involved in this process. He plans to apply genetical, pharmaceutical but also mechanical and microscopic approaches to understand how cell adhesion is maintained in plants.
Contact:
Stéphane Verger
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences
Email:
http://www.upsc.se/stephane_verger
[2020-10-30] Plant cell walls need to be flexible and at the same time rigid to give stability but also allow growth. Glycoproteins, proteins with attached carbohydrates, are only a minor component of the cell wall which consists mainly of cellulose, hemicellulose, pectin and lignin. Nevertheless, modifications of such glycoproteins can have a strong impact on the properties of the plant cell wall. This was shown by Pieter Nibbering, PhD student in Totte Niittylä’s group, who studied cell wall formation in the herbal plant Arabidopsis and in poplar. Pieter Nibbering successfully defend his PhD thesis at the Swedish University of Agricultural Sciences on Friday, 30th of October.
Your thesis focuses on plant cell wall formation in Arabidopsis and aspen. What was interesting you about doing research on cell walls?
I find cell walls very interesting because they so complex. It is very challenging to work with them and I wanted to take on this new challenge. Another reason why I decided for this PhD project was that you cannot just use one or two methods when studying cell walls but need to use many different tools like e.g. molecular cloning, chemistry and protein expression to come closer to an answer of your questions. This diversity was also very interesting for me because it allowed me to learn a lot of different techniques.
You worked with certain glycoproteins that are lesser known components of the cell wall. Why are these glycoproteins important?
That is actually the question we tried to answer during my PhD. We do not know yet why they are important. The difficulty is that approximately 1200 proteins in Arabidopsis are predicted to have this kind of carbohydrates called arabinogalactan glycans attached - not only those ones we worked with. The attached glycans fulfil many different functions. They can e.g. stabilize the protein to make sure that the protein can perform the right function, they can interact directly with the cell wall or with cell wall components or they can bind salts for instance calcium and be involved in signal transduction. For our experiments, we used mutants in which the biosynthesis of some glycoproteins is impaired meaning that the glycans are not added properly to the proteins. The mutants clearly showed growth defects and/or defects in stress response and this let us conclude that the impaired glycoproteins are important for normal growth and stress responses.
Which of your results is the most fascinating for you?
Some of our mutants only showed an obvious difference to our control plants when they were grown under stressful conditions. This is rather what you expect if you modify minor components of the cell wall. However, the growth of other mutants was strongly affected also under optimal growth conditions. This was really unexpected for me because I did not think that a modification of a protein that is adding glycans to some of the 1200 predicted glycoproteins has such a severe effect on the cell wall. We still do not fully understand this result, but we have some ideas and are hopefully close to figure out what the cause is.
What was the biggest challenge you faced during your PhD?
The biggest challenge in my whole PhD was to transfer those proteins to bacteria or tobacco which allows to multiply and isolate these proteins and do functional studies. They need a very specific environment to be active which made the full procedure very challenging. We are still struggling with this, but I will continue on optimizing the process in the next couple of weeks.
Do you think your results might lead to practical applications in future?
We still need to do more research before we come closer to practical applications. When we understand better how modifications of the glycoproteins affect cell wall properties, we might be able to alter the interaction between cell wall components and like this change the properties of the cell wall. We could for example make cellulose or hemicellulose easier to extract which could be interesting for the pulp and paper industry or make the cell walls a bit more bendable or allow that it can expand more. Beside of the mutant studies with Arabidopsis, we also performed a bioinformatic analysis where we predicted which proteins in poplar are glycoproteins and where these proteins are expressed in the wood. Also this study does not result in direct applications but it is groundwork for future research in poplar and closely related species there is the potential for possible future applications.
Do you plan to continue doing research on cell wall or do you have already other plans for your future?
My plan is to go back to the Netherlands, and I am currently searching a postdoc there. It is quite difficult now during the Corona crisis because not many positions open up. I would like to continue doing research on cell walls. There is still a lot to uncover. Unfortunately, not many research groups in the Netherlands are working on cell walls. That is why I am also thinking to write my own postdoc proposal focusing on the role of the cell wall in abiotic stress responses in Arabidopsis but also in crops. I have never worked with crops before and I would like to start with that. On the long run, I would like to do research in a breeding company and working with crops hopefully will help me to come closer to that.
About the public defence:
The public defence took place on Friday, 30th of October at SLU in Umeå. Faculty opponent was Grégory Mouille, Institut Jean-Pierre Bourgin, UMR 1318 INRAE-AgroParisTech, France. Pieter Nibbering's supervisor is Totte Niittylä. The dissertation was live broadcasted on SLU Play: https://play.slu.se.
Title of the thesis: The role and synthesis of β1,3-galactans in plant cell wall formation
Link to the thesis: https://pub.epsilon.slu.se/17817/
For more information, please contact:
Pieter Nibbering
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences (SLU)
Email:
The plant journal New Phytologist has selected a study led by Umeå University researcher Xiao-Ru Wang as its cover story in the October issue. The paper is about effects of landscapes and range expansion on population structure and local adaptation.
“Understanding the origin and distribution of genetic diversity across landscapes is critical for predicting the future of organisms in changing climates”, says Xiao-Ru Wang, professor at the Department of Ecology and Environmental sciences at Umeå University and associated group leader at UPSC.
The study addresses a fundamental question in landscape genetics: the relative roles of population history, geography and natural selection in shaping genetic diversity in wild populations.
In the study, Xiao-Ru and a Chinese research group analyzed diversity and population structure in the pine tree Pinus densata, a keystone species on the Qinghai-Tibetan Plateau. They mapped the genetic variation to geographical and climate variables across the distribution range to establish the contribution of geo- and eco-factors to the observed spatial genetic pattern. Based on this information, the study further simulated how its genetic legacy may limit the persistence of P. densata in future climates.
The results illustrate that significant adaptation to extreme environment, when coupled with reduced diversity as a result of past demographic history, constrains potential evolutionary response to climate change.
As the dominant forest-forming species in the southeastern Qinghai-Tibetan Plateau, the resilience of P. densata underlies regional ecosystem function. Qinghai-Tibetan Plateau is the largest plateau on earth and also the most vulnerable ecosystem. While the deep valleys and high mountain ridges of the Qinghai-Tibetan Plateau have helped to create a global biodiversity hotspot, these same features can constrain adaptive responses to climate change. This is a particular concern for organisms with limited dispersal ability.
“The strong signal of genomic vulnerability in P. densata may be representative for other plateau endemics. As we accumulate further examples, it will become possible to gain a more general understanding of how demography and landscape factors constrain or promote adaptation to novel and changing environments,” Prof. Xiao-Ru Wang explains.
The study was performed in close collaboration with Beijing Forestry University; the joint team has been working together on this study system for more than 20 years.
The original article
Zhao, W., et al: Effects of landscapes and range expansion on population structure and local adaptation. New Phytologist Volume 228, Issue 1, October 2020. Pages 330-3432020. https://doi.org/10.1111/nph.16619
More information about Xiao-Ru Wang's research
More information about evolutionary biology research at Umeå University
Text: Ingrid Söderbergh
An international research team led by Colin Turnbull from Imperial College London and Karin Ljung from UPSC showed that cytokinin, a substance that regulates plant growth, can be sensed on the outside of the plant cell. For a long time, researchers were convinced that cytokinin is mainly perceived within the cell, initiating reactions to adjust the cell’s development. These new findings, that were published last week in the journal Nature Communications, will fuel a 20-year-old discussion.
Cytokinins have many different functions in the plant. They control root and shoot growth, autumn senescence, they regulate cell division and much more. Within the plant cell, cytokinins bind to cytokinin receptors and these proteins then initiate a reaction that leads to, for example, enhanced shoot growth. This was the common view so far. In the current publication, the research team found a proportion of cytokinin receptors also sitting on the surface of the cell and they showed that they are fully functional there.
“The discussion about cytokinin receptor localization started almost 20 years ago when the first receptor was discovered. The recent view was that the receptors were mainly localised in the endoplasmic reticulum, which is a membrane system located within the cell,” explains Ioanna Antoniadi, who is postdoc in Karin Ljung’s group and first author of the article. “However, it was never excluded that the receptors might also sit in the plasma membrane, the membrane surrounding the cell.”
Initially, the researchers wanted to identify which of the different existing cytokinin forms is the active one that regulates root growth and development. They isolated individual cells from the root of thale cress, measured the cytokinin contents within and were really surprised to find similar amounts of active cytokinins inside and outside of the cell.
“We were wondering what these active cytokinins are doing out there and if they could actually be perceived,” says Ioanna Antoniadi, who started this work as part of her PhD thesis in London in 2013. “We started a collaboration with Karel Doležal and his team from the Palacký University in Olomouc, Czech Republic, who developed an incredible tool to answer our question.”
The Czech group synthesized active cytokinin molecules and attached them to sepharose beads that were bigger in size than a plant cell. These bound cytokinins could not enter the plant cell but were still able to activate a cytokinin response in the cell.
During their latest experiments, the researchers got in touch with yet another research team that was coming to the same conclusions as them but used a completely different approach. They were able to publish their results at the same time in the same journal fuelling the ongoing discussion even more.
The article
Antoniadi I, Novák O, Gelová Z, Johnson A, Plíhal O, Simerský R, Mik V, Vain T, Mateo-Bonmatí E, Karady M, Pernisová M, Plačková L, Opassathian K, Hejátko J, Robert S, Friml J, Doležal K, Ljung K, Turnbull C. Cell-surface receptors enable perception of extracellular cytokinins. Nature Communication 11, 4284 (2020).
https://doi.org/10.1038/s41467-020-17700-9
The corresponding article that was published at the same time:
Kubiasová K, Montesinos JC, Šamajová O, Nisler J, Mik V, Semerádová H, Plíhalová L, Novák O, Marhavý P, Cavallari N, Zalabák D, Berka K, Doležal K, Galuszka P, Šamaj J, Strnad M, Benková E, Plíhal O, Spíchal L. Cytokinin fluoroprobe reveals multiple sites of cytokinin perception at plasma membrane and endoplasmic reticulum. Nature Communication 11, 4285 (2020).
https://doi.org/10.1038/s41467-020-17949-0
For more information, please contact:
Ioanna Antoniadi
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences (SLU)
Email:
Karin Ljung
Department of Forest Genetics and Plant Physiology
Umeå Plant Science Centre
Swedish University of Agricultural Sciences (SLU)
Email:
Phone: +46 (0)90 786 8355
https://www.upsc.se/karin_ljung
Colin Turnbull
Department of Life Sciences
Imperial College london
Email: