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Photo: Juha Niemi
SLU is awarding Rosario García-Gil with the Gold Medal for Distinguished Service. The announcement of this years’ Medal recipients came out this week. The two other recipients are Harry Blokhuis who is awarded with the Great Medal and Michael Bertram who will receive the Silver Medal. All three medals honour meritorious contributions for SLU and the sector in which SLU works. They will be officially handed over on the 8th of October during this years’ doctoral degree award ceremony at SLU in Uppsala.
Rosario García-Gil, associate professor at the SLU and group leader at UPSC, started to work at UPSC and SLU in 2005 focussing in her research on applied forest genetics and breeding mainly working with Norway spruce and Scots pine. Since 2019, Rosario García-Gil is also Vice-Dean for internationalisation at the Faculty of Forestry at SLU and member of the Faculty board. The Gold Medal for Distinguished Service rewards “exemplary, exceptional efforts of lasting value” that “benefit SLU or the sector in which the university is active”.
In her research, Rosario García-Gil uses advanced genetic methods to improve and fasten the breeding process. She was recently granted a large research project by the Swedish Foundation for Strategic Research (SSF) in which she aims to develop digital breeding tools to speed up the breeding cycle for Norway spruce and in parallel preserves biodiversity. The ecological sustainability perspective as well as the practical use of the research data and scientific innovations are important aspects of her work.
Rosario García Gil has built a wide collaboration network with other universities, companies and organisations, both within and outside the country which allowed her to receive extensive external research funding. It has also led to the wide dissemination of new results in the scientific community. Moreover, Rosario García-Gil has been involved in popular science activities such as Soapbox science and the Fascination of Plants Day.
According to the nomination letter, Rosario García-Gil’s ambition is to build a better society. She is keen on helping others to grow and progress in their careers. In her role as Vice-Dean for internationalisation, her goals are to increase the impact of the faculty’s science on global issues to develop sustainable models and to integrate the faculty’s international community in faculty-relevant matters and support their career development.
Rosario Garcia-Gil started her education as biologist at the University of Valencia in her home country Spain. After finishing her PhD on molecular plant breeding of fruit trees in 1999, she worked for four years as Marie Curie Postdoctoral researcher at the Department of Biology at Oulu University in Finland. She has been administrator of the second and third Research Schools in Forest Biotechnology and Genetics at SLU, is since 2015 member of the UPSC board and since 2019 member of The Barents Forest Sector Network and of the board of Föreningen Skogträdförädling.
Announcement of this years’ Medal recipients on the SLU homepage (only in Swedish)
General information about SLU’s Medals of Distinguished Service
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Jingfang Hao and Alizée Malnoë are isolating the lumen of chloroplats, an important technique used in the recently published article, in the cold room (photo: Robert Calderon).
Plants need light but too much of it can be harmful. A recent study, led by Alizée Malnoë from UPSC and Umeå University and by Mei Li from the Chinese Academy of Sciences, sheds light into the mechanism on how plants protect themselves from excess of light.
Jingfang Hao, postdoc at UPSC and shared first author of the study, says that the photoprotection they studied here is a biological process named non-photochemical quenching (NPQ), which plants carry out to dissipate the excess absorbed light as heat under strong illumination.
"The negative regulation of this photoprotection is mediated by a chloroplast membrane-anchored protein, SUPPRESSOR OF QUENCHING 1 (SOQ1). SOQ1 consists of a stromal domain, transmembrane domain and lumenal domain containing thioredoxin-like (Trx-like), NHL domain and C-terminal domain (CTD)", says Jingfang Hao and continues:
"The previous study determined that Trx-like domain is essential for SOQ1 suppression function on photoprotection. We discovered that besides Trx-like domain, CTD is indispensable for the negative regulation of photoprotection. The mechanism is that CTD can accept the electron from Trx-like domain and donate the electron to inhibit the target protein required for NPQ".
Why is this an important finding?
"Because this is the first study to report the crystal structure of SOQ1 lumenal domain and determine the function of the C-terminal domain of SOQ1 protein. Our findings uncover a new mechanism that how plants protect themselves from strong illumination".
Jingfang Hao tells further that investigating the localization of SOQ1, she isolated the chloroplast sub-fractions such as intact thylakoids, thylakoid membranes and lumen.
"I was surprised to find SOQ1 can be cleaved as several truncated forms in the lumenal fraction. Our Chinese colleagues also found these truncated forms when they purified the SOQ1 lumenal domains from bacteria. These findings suggest that the truncated forms could play some physiological functions".
What use will your findings have?
"The structure of the SOQ1 lumenal domain can provide a reference for the researchers to study similar proteins or proteins containing similar domains in other species. Moreover, our findings give a contribution to understanding how plants adapt the stressful environments".
To celebrate the article, Jingfang got a cake from her colleagues illustrating their new findings (photo: Robert Calderon).
The article
Yu G#, Hao J#, Pan X#, Shi L, Zhang Y, Wang J, Fan H, Xiao Y, Yang F, Lou J, Chang W, Malnoë A*, Li M*. Structure of Arabidopsis SOQ1 lumenal region unveils C-terminal domain essential for negative regulation of photoprotective qH. Nat. Plants. 2022 Jul;8(7):840-855. https://doi.org/10.1038/s41477-022-01177-z
SOQ1 is a protein in the leaves that manages the amount of light absorbed. Previously, only the part T and N of this molecular machine were known. In the study, the researchers identified the new part C of this machine and now they are able to understand how it works. SOQ1 has been found to have similarities to a bacterial protein which is known to transfer electrons between the different parts and thus changes the activity of other proteins. The researchers hypothesize that the same thing is happening in the leaf of plants and they are now working on finding the target protein of SOQ1 and how it modifies it exactly.
Not only bacteria and plants but also humans and animals have a version of SOQ1 which when mutated reduces the lifespan to only two short years. The researchers hope that their plant biology research can help to understand the function of SOQ1 in humans and tell more about the neurodegenerative disease in which it is implicated. It is a rare disease whose English acronym is FINCA, or syndrome of fibrosis-neurodegeneration-cerebral angiomatosis. Thanks to plant research, it is also known that SOQ1 acts on a protein, whose human counterpart is involved in Alzheimer's disease. However, the researchers think that it will take them much longer to determine if SOQ1 plays a role in Alzheimer's disease, too.
For questions, please contact:
Alizée Malnoë
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
https://www.upsc.se/alizee_malnoe
https://malnoelab.com/
Jingfang Hao
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
Text: Per Melander, Jingfang Hao
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Group picture of Alizée Malnoë's group with (from left to right) Aurélie Crepin, Alizée Malnoë, Pierrick Bru, Paola Puggioni, Fadime Demirel & Jingfang Hao (taken in May 2022 by Robert Calderon)
She could have been on Svalbard today, presenting her research and receiving the Early Career Prize from the Scandinavian Plant Physiology Society (SPPS) during the SPPS Congress 2022. Instead, she is taking on a different challenge. Alizée Malnoë, Associate Professor at Umeå University and group leader at UPSC, is currently on maternity leave and raising a baby. Read more about her research, why she became a group leader and joined UPSC in the interview below!
You were supposed to personally receive the SPPS Early Career Prize today on Svalbard during the SPPS Congress 2022. Do you regret that you could not go there and join the conference this week?
Alizée Malnoë: No, I do not regret it! I have attended and presented at many conferences since I started my PhD in 2007, and I am in the process of a challenging time-course experiment: breastfeeding a 4-month-old baby!
The SPPS Early Career Prize is - according to the SPPS homepage - given to “young, highly talented scientist, who has shown good progress and made significant, independent contributions to plant biology”. How does it feel to be awarded?
Alizée Malnoë: It feels really nice. I am grateful to have been nominated and awarded this prize by my colleagues since hard work does not always pay off! I am also very thankful to my mentors, collaborators and past and current group members.
You are awarded for your work on photoprotection in plants. What fascinates you about this topic?
Alizée Malnoë: I am fascinated by plants who can just stand there in the bright sun and not get sunburnt. It is amazing that they have evolved both the capacity to use the energy from sunlight for photosynthesis and the ability to dissipate the excess energy that would otherwise be harmful. A good example of the Swedish philosophy “lagom”: not too little, not too much light.
Did you always want to become a scientist?
Alizée Malnoë: I liked biology from childhood and had a kids laboratory kit! But I had no idea that I would pursue a PhD because I had thought it would be way too difficult.
Do you remember a key moment that influenced your decision to go on in academia and start your own group?
Alizée Malnoë: While mentoring students during my postdoctoral training, and sharing the fun of doing science, they told me “You’d be a great PI” which was a big confidence booster!
Why did you choose UPSC to start up your group?
Alizée Malnoë: Joining UPSC solved my family’s so-called “two-body problem” by giving work opportunities for both me and my husband, who himself is a plant scientist. With an ongoing tradition of photosynthesis research and possibilities for collaboration, plus the overall strong scientific environment of UPSC and its balanced and kind work-culture, it was an easy decision.
The SPPS prize is a monetary award. Do you have already an idea what you will do with it?
Alizée Malnoë: I will celebrate with my group and we will go eat something very nice.
Alizée Malnoë started her research group at UPSC in January 2018 after a Postdoc in Krishna K. Niyogi’s group at the University of California, Berkeley. She and her group study the molecular mechanisms that plants use to prevent damage by excess sunlight, a process called photoprotection. The SPPS Early Career Prize is acknowledging her (and her co-workers) research achievements in this field. It is given to young, talented scientists, who independently made important contributions to plant biology and who received their PhD less than 10 years before the SPPS Congress.
During the SPPS Congress in Svalbard, another scientist from UPSC, Kristoffer Jonsson, will also receive a prize, the SPPS PhD Prize. He was awarded already in 2021 but could not officially receive the prize because the SPPS Congress was postponed to 2022. Have a look here in case you would like to read more about Kristoffer Jonsson’s research and his prize
More information about the SPPS Prizes
For questions, please contact:
Alizée Malnoë
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
https://www.upsc.se/alizee_malnoe
https://malnoelab.com/
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Young aspen trees lacking starch reserves (middle and right) grow as well as trees with starch (left). The starchless pgm mutant trees were created using the gene editing tool CRISPR-Cas9 which works as a pair of high-precision genetic scissors (pgm: PHOSPHOGLUCOMUTASE gene; photo: Wei Wang).
Aspen trees are not relying on their starch reserves when grown under benign conditions. This is shown in a new study with modified aspen defective in starch synthesis. The starch-lacking trees were also absorbing less carbon dioxide compared to non-modified trees, but their growth and performance was not affected. The study done by Totte Niittylä’s group from Umeå Plant Science Centre and SLU was published today in Current Biology.
About one third of the annual human-made carbon emissions are removed from the atmosphere by terrestrial photosynthesis and trees play a crucial role in this process. Like all plants, trees invest the carbon-containing sugars produced during photosynthesis either directly into growth, or they save them for future use - mainly in the form of starch. Increased atmospheric carbon dioxide levels stimulate photosynthesis, but its effect on trees is uncertain. How is the carbon used in trees? Totte Niittylä and his group set out to tackle this question from the opposite direction, by disrupting starch synthesis.
A lack of starch does not affect tree growth and biomass production
“We used the CRISPR-Cas9 technology, the genetic scissor, to introduce mutations in two genes that are essential for starch synthesis in aspen,” explains Wei Wang, postdoc in Totte Niittylä’s group and the first author of the study. “The modified trees contained no starch and assimilated up to 30 percent less carbon dioxide, but the growth and biomass production were not impacted – at least under the benign conditions that the trees experienced in the greenhouse.”
The researchers used different light conditions such as shorter days or low light levels to see how the modified trees deal with a shortage of carbon supply resulting from reduced photosynthesis. However, the modified trees did not show any sign of performance loss when compared to non-modified trees. The researchers concluded that aspen trees passively save carbon in the form of starch, contrasting the annual model plant Arabidopsis that depends on its starch reserves for normal growth.
Seasonal growth of aspen trees does not depend on starch reserves
To test if the perennial growth style of aspen trees requires starch reserves, the researchers simulated seasonal growing conditions in the greenhouse. Previous publications have indicated that starch is important for bud flush in the spring when photosynthesis is limiting. Surprisingly, the starch-lacking aspen trees set and flushed their buds in the same way and at the same time as non-modified trees.
“It was striking for us to see that aspen trees cope so well with the lack of starch and do not need it for the seasonal growth-dormancy cycle,” states Totte Niittylä, senior lecturer at SLU and group leader at Umeå Plant Science Centre. “The results also suggest that the needs of the growing tissues largely determine how much carbon dioxide is assimilated by the trees. This is important knowledge when estimating the capacity of trees to take up carbon dioxide from the atmosphere.”
The article
Wei Wang, Loïc Talide, Sonja Viljamaa and Totte Niittylä (2022) Aspen growth is not limited by starch reserves. Current Biology, https://doi.org/10.1016/j.cub.2022.06.056
Link to the article in Current Biology
For more information please contact:
Totte Niittylä
Umeå Plant Science Centre
Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences
Email:
https://www.upsc.se/totte_niittyla
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Fertilisation promotes plant growth but changes the plant’s interaction with their mycorrhizal fungal partners (Photo by Dalibor Perina on Unsplash)
How do nutritional changes affect the interaction between trees and soil microorganisms? This has long remained a black box but a new study has shed light onto this cryptic association. It shows that increased soil nutrition changes the communication between trees and their associated fungi, restructuring the root-associated fungal community with major implications for carbon cycling in the forest.
The study was published today in Proceedings of the National Academy of Sciences. Researchers from Umeå Plant Science Centre, a collaboration between Swedish University of Agricultural Sciences and Umeå University, were leading the study and were supported by Science for Life Laboratory researchers from Stockholm University and Uppsala University.
Advances in sequencing techniques have made it possible to capture the dynamics of how tree roots and their fungal partners interact with each other. The researchers from Swedish University of Agricultural Sciences, Umeå University and Science for Life Laboratory compared a forest that was fertilised continuously over 25 years with a non-fertilised forest. They analysed the gene activity in tree roots and in over 350 fungal species over the course of a growing season and revealed that the fertilised trees changed their communication strategy and became more hostile to their fungal partners. As a result, the fungal community shifted from being dominated by specialist to more versatile species.
“In nutrient-poor boreal forests, trees are reliant on root-associated myccorhyzal fungi for their nutrient supply and maintain this partnership through the exchange of valuable sugars”, says Simon Law, first author of the study and former postdoc in Vaughan Hurry’s group at Umeå Plant Science Centre. “Soil fertilisation disrupts this sensitive trading relationship, causing trees to divert these sugars to their own growth and defence, with profound implications for the fungal community.”
Stress tolerant fungi are promoted in fertilised soils
The researchers showed that fertilised trees reduced the activity of genes that encode the information for sugar exporting proteins, while bolstering defence processes. The specialist myccorhyzal fungal species that are highly dependent on the carbon-containing sugars from the trees were the hardest hit. By ramping up their defence processes, the plants made root colonisation by these specialist fungi even more difficult and they became less abundant.
In contrast, metabolically versatile fungal species with less reliance on the trees flourished in the fertilised forests. These myccorhyzal fungi are characterised by dark coloured, resilient, cell walls that make the fungi more resistant to stress but also make the cell walls slower to decompose. This shift in the fungal community also influences the carbon cycling in the soil because the specialist fungi play an important role in decomposing plant litter. It has been shown in other studies that fertilisation of the northern conifer forests increases carbon storage both in the above ground plant tissues and in the soil. This new study provides insights into the underlying mechanisms of the soil storage processes.
“It is well known that fertilisation leads to an increase in carbon storage in the above ground tissues of the trees at the expense of the below ground root and fungal network”, explains Vaughan Hurry, professor at the Swedish University of Agricultural Sciences. “But what this study shows is the complexity of the communication between the tree and the associated fungal community – and it highlights the importance of the tree’s voice in that communication.”
Nutritional changes affect carbon cycling in boreal forests
The conifer-dominated boreal forest circles the Northern Hemisphere and contains the largest terrestrial carbon store on Earth, potentially playing a vital role in mitigating climate change. Warming temperatures will increase the decomposition of dead material in the soil and thus increase nutrient cycling. This will affect the nutrient status of the trees and their associated fungal partners.
The researchers show that the complex relationship between trees and their associated microorganisms needs to be better understood to improve predictive models of how changing environmental conditions affect carbon and nutrient cycling in boreal forests.
Starting point for many more studies
“The relationship between the different organisms in the soil is hugely complex and has been largely inaccessible. The sequencing approach we have used allows us to probe these complex interactions at a molecular level, telling us who is there and what are they doing”, says Nathaniel Street, second corresponding author of the study and associate professor at Umeå University. “The approach we used in this study offers many new possibilities and we think that, in the long run, this will enable us to better understand the functional mechanisms driving ecosystem dynamics.”
The massive amount of data that the researchers have collected in their study on plant roots and soil microorganisms is made publicly available via an online tool, the Boreal Rhizospheric Atlas, that is hosted by the Science for Life Laboratory. Researchers can access this tool freely and explore the data further. The future plan is to include data from additional studies in the tool to shine further light on the complex relationship between plants and soil microorganisms.
The article
Simon R. Law, Alonso R. Serrano, Yohann Daguerre, John Sundh, Andreas N. Schneider, Zsofia R. Stangl, David Castro, Manfred Grabherr, Torgny Näsholm, Nathaniel R. Street, Vaughan Hurry (2022) Metatranscriptomics captures dynamic shifts in mycorrhizal coordination in boreal forests. Proceedings of the National Academy of Sciences (PNAS), 119 (26) e2118852119; doi.org/10.1073/pnas.2118852119
For more information please contact:
Vaughan Hurry
Umeå Plant Science Centre
Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences
Email:
https://www.upsc.se/vaughan_hurry
Nathaniel Street
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
https://www.upsc.se/nathaniel_street
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Regina Gratz (fourth from left) together with all other awardees and The King (middle) after the award ceremony in the Royal Palace (Photo: Clas Göran Carlsson).
Wednesday last week was a special day for Regina Gratz, researcher in Torgny Näsholm’s group and employed at the Department of Plant Physiology and Forest Genetics at UPSC and SLU. The King handed her over a scholarship from the King Carl XVI Gustaf 50th Anniversary Fund for Science, Technology and the Environment. Regina Gratz will use the scholarship to study how nitrogen fixing bacteria can be stimulated so that in the long run the usage of mineral fertilization can be reduced.
Thirteen scholarships were granted in total. The awardees did not apply but were nominated and the names of the awardees were already announced in the end of April in connection with the H.M. King Carl XVI Gustaf’s birthday. The official ceremony took place last week, on May 25 in the Royal Palace.
Regina Gratz’s project is based on results that organic nitrogen can stimulate biological nitrogen fixation. Together with researchers from the University of Hohenheim in Germany, she plans to identify the molecular mechanisms underlying this observed positive effect.
The King Carl XVI Gustaf 50th Anniversary Fund for Science, Technology and Environment exists since 1996. It was founded to celebrate His Majesty’s 50th birthday and aims on promoting research, technological development and enterprises that contribute to a sustainable use of natural resources and the maintenance of biodiversity. Especially young scientists working in Sweden are promoted.
Official news from the Swedish Royal Court (only in Swedish)
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PhD student Andreas Schneider (Photo: Laura Hinojosa)
How do forest management strategies that aim on improving plant growth influence the fungal community? Andreas Schneider, PhD student in Nathaniel Street´s group at Umeå Plant Science Centre, has contributed to the development of new sequence analysis methods that make it easier to study fungal communities. He will defend his PhD thesis on Wednesday, 1st of June 2022 at Umeå University.
Studying fungal communities in the forest soil is very challenging. The mushrooms seen in the forest in autumn are just made by some of the fungi to spread their spores. The most time of their lifecycle fungi are hidden in the soil or inside of the roots of their host plants. Recently developed advanced sequencing techniques offer many new possibilities and Andreas Schneider and his colleagues used these advances to develop automated bioinformatic tools that allow to study the dynamic and diversity of fungal communities in the soil.
“Many of the methods used to study fungi today are indirect. We take a soil sample, extract DNA from it and see to which species this DNA might belong to,” explains Andreas Schneider. “We used these methods in some of our studies, but one problem is that you do not know if the DNA comes from fungi that are dead or from some that are alive and active. That is why we used and further developed another method that is also indirect but that shows how active the fungi are. The great thing is that this can tell us what the fungi are up to, which genes are being expressed.”
To test their method, the researchers analysed how nitrogen addition affects the fungal community. Swedish forests are usually low in nitrogen and conifer trees compensate for this limitation by establishing the symbiosis with mycorrhizal fungi. The trees deliver carbon to the fungi and receive nitrogen in return. For seedlings on reforestation sites, it is crucial to establish the connection with the fungi to improve their chances to survive.
“Nitrogen addition, especially in high doses, is already known to change the fungal community in the soil quite a lot. Our experiments show that small amounts of organic nitrogen fertilization do not affect the fungal community but can improve the survival and growth rates of seedlings,” says Andreas Schneider. “This was true for seedlings coming from nurseries and also for seeds that were directly placed on the field site. We still need to follow up on the seedling growth rates over a longer period of time and for more different local conditions, but the current results are very promising.”
In a different approach, Andreas Schneider and his colleagues analysed why nitrogen addition inhibits the degradation of lignin in forest soils. Lignin is the component in dead plant material that is decomposed the most slowly by white-rot fungi. The researchers could show that nitrogen addition affects chemical processes in the soil and that this can have a negative impact on the efficiency of white-rot fungi.
They could also confirm that the composition of the fungal community associated with tree roots is changed on sites with high nitrogen fertilization favouring nitrogen tolerant fungi species. This can be caused both by soil chemistry changes and by a reprogramming of the mycorrhizal symbiosis from the side of the host tree.
“We could show that our methods are working and are useful to study dynamic changes in the fungal community”, thinks Andreas Schneider. “The biggest limitation now is the lack of genetic information for most fungal species, but we and many others are working on that. I am sure that in the future, this new knowledge and these methods will help us to evaluate even better how different forest management strategies influence fungal activity and biodiversity.”
About the public defence:
Andreas Schneider, Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, will defend his PhD thesis on Wednesday, 1st of June 2022. Faculty opponent will be Colin Averill, Department of Environmental Systems Science, ETH Zurich, Switzerland. The thesis was supervised by Nathaniel Street. Andreas Schneider was part of the PhD Research School in Forest Genetics, Biotechnology and Breeding and collaborated for his PhD project with Holmen Skog.
Title of the thesis: Perturbance and stimulation - using nitrogen addition and high throughput sequencing to study fungal communities in boreal forests
For more information, please contact:
Andreas Schneider
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
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Peter Marhavý at the UPSC microscopy facility (Photo: Fredrik Larsson)
The Gesellschaft für Biochemie and Molekularbiologie (GBM) gives out every year the FEBS Anniversary Prize to acknowledge a senior researcher under 40 years of age for outstanding achievements in the field of biochemistry and Molecular Biology or related sciences. This year, Peter Marhavý, group leader at UPSC, is receiving the prize and is invited to give a talk at The Biochemistry Global Summit in July in Lisbon, Portugal.
It was last week, when Peter Marhavý was informed by FEBS, the Federation of European Biochemical Societies, that he will be awarded with this years’ FEBS Anniversary Prize. Peter Marhavý joined UPSC as new group leader in 2020 after postdocs at The Institute of Science and Technology Austria and at the University of Lausanne. He and his group want to understand how plant roots respond to wounds with special focus on cell-to-cell communication.
“I am very happy that my scientific contribution is appreciated, and I am extremely honoured to have received such a distinguished prize", says Peter Marhavý who works as Assistant Professor at the Swedish University of Agricultural Sciences.
FEBS is one of the largest molecular biology societies in Europe. The FEBS Anniversary Prize will be hand over during the IUBMB-FEBS-PABMB Congress 2022 in Lisbon, The Biochemistry Global Summit. It comprises a certificate and 2000€ and is given out by GBM since the 10th anniversary of FEBS.
Link to the press release from FEBS: https://www.febs.org/news/febs-anniversary-prizes-2022/
For more information, please contact:
Peter Marhavý
Umeå Plant Science Centre
Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences
Email:
Twitter: @pmarhavy
https://www.upsc.se/peter_marhavy
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PhD student David Castro at one of his field sites close to Sollefteå.
How do soil properties and microorganisms in the soil influence seedling growth? David Castro, PhD student in Vaughan Hurry’s group at UPSC and SLU showed in his PhD thesis that understanding this complex relationship between the three partners can help to optimize biodiversity-friendly forest management and to get a better picture about the ecology of endemic species. David Castro will defend his PhD thesis at the Department of Forest Genetics and Plant Physiology, SLU, on the 24th of May.
During your PhD, you were funded by a scholarship that you got from Chile. That is very unusual for a PhD student in Sweden. What motivated you to apply for that scholarship and come to Umeå to do your PhD in Vaughan Hurry’s group at UPSC?
In 2015, me and my wife came to Umeå together with Cristian Ibáñez to work for a month with Maria Eriksson. We both fell in love with Umeå and the facilities at UPSC are amazing. It was also the time when I was preparing the papers to apply for the fellowship in Chile. I read about Vaughan Hurry’s research on suboptimal environments which was close to what I was working on during my Master thesis. I met with Vaughan, and he agreed on supporting my application for the fellowship which I luckily also received. It took then still one and a half years and many nerves until all papers were ready that I could finally come and start my PhD in Vaughan Hurry’s group. I am really happy that it all worked out and that I now can defend my thesis.
The title of your thesis starts with the question “Who comes first?” and mentions later the plant-microbiome-soil continuum. Can you answer the question now and why do you call it “continuum”?
“Who comes first” is rather a rhetorical question. The goal of my thesis was to understand the links between the plant, the microorganisms in the soil and the soil itself. We assessed plant growth and soil characteristics and used advanced sequencing techniques and bioinformatics methods to analyse how the plant and the microorganism, especially fungi, react to their environment. All three components are important and feedback each other. By allocating carbon to attract beneficial microbial partners, the plant’s roots modify locally the fungal and bacteria composition and also soil characteristics like for example soil particle aggregation, pH value and carbon content. Fungi and bacteria also allocate and move nutrients. Then there are also the physical and chemical characteristics of the soil which change during the year depending for example on the water content which is affecting the nutrient availability. That is why we cannot say who comes first. Every of the three partners influences continuously the other partners in a very complex manner and form together a kind of unit or “continuum”.
What do you consider as the major outcome from your studies?
One part of my thesis was on Prosopis species that are partly endemic in Chile but very invasive in other parts of the world and therefore of ecological interest. In Chile, Prosopis is growing partly on soil with very particular characteristics like for example in the Atacama Desert. Our experiments showed that when Prosopis seedlings manage to recruit beneficial fungal partners, they grow well in various kinds of soils except of in soil from the Atacama Desert which is very salty. This counts even for seedlings of Prosopis tamarugo which is growing very isolated in the Atacama Desert. The other parts of my thesis focussed on Scots pine and Norway spruce which are of economic importance here in Sweden. We could show that small amounts of nitrogen fertilization improve plant growth but only very minorly affects soil ecology and the fungal composition. Strong nitrogen fertilization has a positive effect on plant growth but strongly impairs the microbiota and also the soil ecology which can have a major impact on forest biodiversity.
What was the most unexpected result you got during your PhD?
We were expecting that Prosopis tamarugo which is growing in the Atacama Desert to be very stress tolerant but that was not the case. Actually, it showed to be a kind of weak seedling which had problems to recruit fungal partners during our experiments. Instead, the seedlings recruited many bacterial partners and we think that this was to partially compensate for the lack of fungi. They survived significantly less in its native soil that we used for our experiments. This was surprising because they have the potential to grow in this soil. Another species that we worked with, Prosopis chilensis, managed to recruit fungi even in soil from the beach but not Prosopis tamarugo which is growing in the most toxic soil in the desert. Our hypothesis is that the individuals, that are growing in the Atacama Desert, established themselves there when it was not as arid as it is now - probably about 100 years ago. The trees or bushes form a taproot which goes very deep into the soil and can reach the ground water. Once this root is established, they can survive also in such an extreme climate like in the Atacama Desert but for a seedling this environment is too harsh.
What was the biggest challenge you faced during your PhD?
Beside suddenly start working in English, it was very hard to learn bioinformatics. I knew a few things from before, but the work here was a different level. I got a lot of help from the people from the Bioinformatics facility at UPSC and from my colleagues. It took time and I followed many courses but now I feel proficient and confident to do bioinformatic analyses and add these skills to my CV.
What are you planning to do now?
I do like to live in Umeå and I would like to stay here even though the winter can be tough. I would also like to keep working with soil ecology and maybe include more the bacterial perspective as we focussed more on the fungal site during my PhD. There is not much done on bacterial soil ecology in the forestry context and I would like to work more on that. I would also like to reanalyse some of the data that we got focussing more on bacteria to see if we can get out more information that we have not seen yet. That is why I am currently looking for a postdoc.
Prosopis seedlings that David Castro and his colleagues used in their experiments.About the public defence:
David Castro, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, will defend his PhD thesis on Tuesday, 24th of May 2022. Faculty opponent will be Barbara Hawkins, Centre for Forest Biology, University of Victoria, Canada. The thesis was supervised by Vaughan Hurry. The dissertation will be live broadcasted via Zoom.
Title of the thesis: Who comes first? Implications of the plant-microbiome-soil continuum feedback on plant performance
Link to the thesis: https://pub.epsilon.slu.se/27682/
For more information, please contact:
David Castro
Umeå Plant Science Centre
Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences
Email:
Twitter: DavidCastroMor6
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PhD student Pushan Bag at Nydalasjön in Umeå (Photo: Jenna Lihavainen)
What allows conifer trees to stay green during winter when temperatures are low but solar radiation is high? Pushan Bag, PhD student in Stefan Jansson’s group at Umeå Plant Science Centre, showed that conifers have evolved special mechanisms that prevent damage to their photosynthetic machinery. He will defend his PhD thesis at the Department of Plant Physiology, Umeå University, on the 20th of May.
What led you come to Umeå and start your PhD on winter acclimation of conifer trees in Stefan Jansson’s group at UPSC?
Pushan Bag: I was working on photosynthetic acclimation of algae in my master’s at the University of Hyderabad in India. We were investigating the effect of salt stress on photosynthesis by using different salts and growing algae under controlled conditions. For my PhD, I did not want to work with “artificial” controlled conditions but instead I wanted to understand natural adaptations under “real” conditions. At that time, Stefan had a PhD position focussing on conifer trees growing in boreal forests. These forests are one of the harshest environments for plants and that was interesting me. So, I applied and came here in 2017.
How did you acclimatise to the Nordic winter?
Pushan Bag: Well, I arrived here on the 17th of February 2017, and February is the coldest time of the year in Umeå. On the very next day after I arrived, I had to collect samples from the forest behind the SLU building. It was fun! To be honest, I love the Nordic winter and the snow, probably because I am from Kolkata and we do not see winter temperature dropping below 5°C. Here in Umeå, I can do some winter sports, which I could not do back in Kolkata.
You worked with Norway spruce and Scots pine and followed the changes that happen in their needles throughout the year, but you set a special focus on spring. What is so special with this season?
Pushan Bag: Spring in the Nordic climate is very different than spring in any other parts of the world. Air temperatures remain well below zero – we measured even -25 °C in February and March 2018 -, while the sun shines very bright. This makes acclimation extremely tough. Sun light drives photosynthetic reactions, but freezing temperatures make it difficult to conduct those photosynthetic reactions. Another problem the plants face is that reactive oxygen species are generated under such high solar radiation and they can damage the photosynthetic machinery.
What is the major outcome from your studies? Can you explain why conifer needles can stay green throughout the year?
Pushan Bag: We discovered that conifers possess a kind of “spill-over” mechanism to protect their photosystems from energy overload. These are the functional units where photosynthesis takes place. The structure of the inner membranes in the chloroplast is changed during winter so that the two photosystems are in physical contact with each other. This is a kind of short cut that allows direct energy transfer from photosystem II to I which is normally not possible. As far as I know, this “spill-over” mechanism was not reported before for any other vascular plant. Conifers are pretty unique in this sense!
What was the most unexpected result you got during your PhD?
Pushan Bag: We found another mechanism that conifer needles have developed to protect their needles from damage by reactive oxygen species. These results are not published yet but they were really unexpected. We hope the paper will be accepted soon.
What was the biggest challenge you faced during your PhD?
Pushan Bag: I think the biggest challenge for me was to learn that in science multiple possibilities can be correct at the same time. Plant species are very different from each other. They have evolved different regulatory ways and they can respond to the same stimuli in different ways. We often tend to generalise mechanisms and functions based on results from one model plant. However, like in our case, it can help to look on different contrasting possibilities to understand a natural phenomenon and maybe discover some new mechanisms.
You recently received a long-term postdoctoral fellowship from the International Human Frontier Science Program Organization and will start working with Professor Barry Bruce at the University of Tennessee in Knoxville. What do you think will you miss most from UPSC and Umeå?
Pushan Bag: Everything!!! I will most certainly miss my friends here in Umeå and also the working culture at UPSC, but I will take all my memories with me and I am looking forward to my new project.
About the public defence:
Pushan Bag, Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, will defend his PhD thesis on Friday, 20th of May 2022. Faculty opponent will be Francis Andre Wollman from the Institute of Physico-Chemical Biology (IBPC), Laboratory of Membrane and Molecular Physiology of Chloroplast at Sorbonne Université in Paris, France. The thesis was supervised by Stefan Jansson.
Title of the thesis: How could Christmas trees remain ever green? Photosynthetic acclimation of Scots pine and Norway spruce needles during winter
Link to Pushan Bag's PhD thesis
Further reading
For more information, please contact:
Pushan Bag
Umeå Plant Science Centre
Department of Plant Physiology
Umeå University
Email:
Twitter: @BagPushan