Lifting response of hybrid aspen: Time-lapse video showing 28 days of the tension wood response of a wild type hybrid aspen (Populus tremula x P. tremuloides). Video created by Bernard Wessels.
Link to the thesis: urn:nbn:se:umu:diva-151724
|What is ethylene?|
|Did you ever experience that your green bananas ripened faster when you placed them next to an apple? This is caused by the plant hormone ethylene that is produced by the ripening apple. Ethylene is a colourless gas with a faint sweet odour that acts as a hormone in plants. It stimulates fruits to ripe but it is also involved in many other aspects of plant development, e.g. like germination of seeds, senescence, reaction to environmental stresses or mechanical wounding. Ethylene is of high commercial interest because it fastens the ripening process of fruits and vegetables and the senescence of cut flowers.|
About the thesis defence:
On Friday, the 5th of October, Bernard Wessels, Department of Plant Physiology, Umeå University, defended his thesis, entitled ’The significance of ethylene and ETHYLENE RESPONSE FACTORS in wood formation of hybrid aspen’. The public defence took place at 9:00 am in Lilla hörsalen ( KB.E3.01) in the KBC building, Umeå University. The faculty opponent was Prof. Kurt Fagerstedt, Faculty of Biological and Environmental Sciences, University of Helsinki, Finland. Supervisor of the PhD thesis was Hannele Tuominen.
For more information, please contact:
Bernard Wessels, Department of Plant Physiology, Umeå University
Telephone +4670 0130923
This year’s UPSC Days were organised by a committee representing one member of every staff category, i.e. PhD students, Postdocs, administration and technical personal and group leaders. Their aim was to compile a program that is interesting for everyone working at UPSC and that stimulates internal communication and interactions.
Link to the programme of the UPSC Days 2018
Text: Domenique André, Carolin Seyfferth, Anne Honsel
A research team led by Markus Schmid has identified a new player regulating plant development under low temperatures. The researchers searched for mutants that have strong growth defects when grown at low temperatures but look otherwise normal. They found the porcupine mutant and showed that the PORCUPINE gene is crucial for normal plant development at low temperatures. Their results are published as Brief Communication article in the journal Nature Plants.
Plants react to changing temperatures by adjusting their development and growth rate. The mutant, that lost the active PORCUPINE gene, grows very slowly at lower temperatures (16°C), displays sever developmental defects and is not able to produce seeds. However, it looks almost like non-mutated plants when growing at favourable temperatures (23°C). The researchers around Markus Schmid concluded that the PORCUPINE gene is required specifically at low temperatures and is crucial for adjusting the plant development and growth to low temperatures.
A recently suggested important mechanism that allows plants to adjust their growth and development to changes in temperature is the so-called alternative splicing (see also below). This process enables a single gene to produce different protein versions depending on which parts of the gene are spliced together and translated. The resulting proteins are altered in their structure and can have different functions. There are factors that regulate which protein variant is synthesised by alternative splicing. PORCUPINE appears to be one of those factors that regulates alternative splicing events under cold temperatures.
Many of the alternative splicing events that take place in the non-mutated plant at lower temperatures are missing in the mutant that lost the active PORCUPINE gene. “We think that PORCUPINE plays a crucial role for connecting plant responses to low temperature with plant development via alternative splicing”, explains Markus Schmid. “This is a new but very complex regulation pathway that we just now start to explore.”
The PORCUPINE gene got its name from the special look of the mutant that lost the functional PORCUPINE gene. The leaves of the mutant are radialised and the hairs (trichomes) on the surface of the mutant are often branched more frequently, giving the mutant a very “spiky” appearance – reminiscent of a porcupine.
|What is alternative splicing?|
|When a gene gets activated its DNA sequence is first transcribed into pre-mRNA (precursor messenger ribonucleic acid). Many pre-mRNAs in plants and animals are than spliced to remove parts (introns) that do not contain information for the encoded protein. The remaining “exons” are stitched together to form a mature mRNA, which is subsequently translated into a protein. Depending on which intros are spliced out and which exons are joined together, different mRNAs can be produced from a single gene, resulting in different protein versions.|
Giovanna Capovilla, Nicolas Delhomme, Silvio Collani, Iryna Shutava, Ilja Bezrukov, Efthymia Symeonidi, Marcella de Francisco Amorim, Sascha Laubinger & Markus Schmid (2018) Nature Plants, doi.org/10.1038/s41477-018-0176-z.
PORCUPINE regulates development in response to temperature through alternative splicing
Link to the publication: https://www.nature.com/articles/s41477-018-0176-z
For more information, please contact:
Markus Schmid, professor
Umeå Plant Science Centre
Department of Plant Physiology
Leaves turn yellow naturally, in autumn, when they get old or when the plant is exposed to stresses like darkness or drought. Daria Chrobok compared in her PhD thesis different scenarios of leaf yellowing and analysed what happens on the metabolic level. She showed that mitochondria, the respiratory power stations of the cell, are crucial for a coordinated adjustment of metabolism during leaf yellowing. Mitochondria stay active until the last stages of leaf yellowing to provide the energy that is needed for recycling nutrients from the dying leaf. Daria Chrobok successfully defended her thesis on the 8th of June.
The yellowing of a leaf, also called senescence, occurs naturally in for example deciduous trees in autumn or when annual plants get old and produce seeds. However, also stresses like a lack of nutrients, drought or pathogens can induce senescence. Daria Chrobok compared naturally aging plants with plants where senescence was induced by darkening a single leaf. She showed that in both cases the mitochondria remain intact until the last stages of leaf senescence to provide the energy needed for the mobilisation and transport of nutrients.
In addition, she showed that especially the amino acid glutamate, that can be easily transported within the plant, accumulates during leaf senescence. She hypothesized that this accumulation of glutamate in the mitochondria and its conversion to glutamine in the cytosol are essential steps for the reallocation of nitrogen rich compounds to other parts of the plant.
The export of amino acids with high nitrogen content into developing parts of the plant, e.g. seeds, is of high importance to ensure that those seeds contain enough nitrogen and the survival of the next generation is guaranteed. Nitrogen is often a limiting factor for plant growth and development and therefore the reallocation of nitrogen during senescence is important for plants.
Without light, plants cannot perform photosynthesis and produce energy-rich carbon compounds like sugars. If only one leaf is darkened, the covered leaf will rapidly turn yellow. In contrast, when the whole plant is darkened, the leaves are repressing this induction of senescence, i.e. they stay green. The plant keeps all components needed for photosynthesis alive and intact so that upon sudden light exposure, the plants are ready to start photosynthesis and continue growing.
Daria Chrobok and her colleagues analysed how plants adjust their metabolism to those two darkening conditions and they compared these results with the light-dependent “stay-green” mutant. When one leaf of a stay-green plant is darkened, it stays green, whereas the same treatment in a wild type plant leads to the yellowing of the darkened leaf. This darkened stay-green leaf, as well as the whole darkened plant accumulate amino acids, especially those with high nitrogen and low carbon content.
The understanding of how “stay-green” plants manage to stay green is interesting for the food industry to keep vegetables green for longer time and for agriculture, to ensure proper grain and nutrient filling as well as other improved traits for crop plants.
The public defence took place in Lilla hörsalen at KBC, Umeå University, on Friday, 8th of June 2018. Faculty opponent was David Macherel, IRHS-MitoStress, University of Angers, France. Supervisors were Olivier Keech and Per Gardeström.
Title of Daria Chrobok’s thesis: “To “leaf” or not to “leaf” - Understanding the metabolic adjustments associated with leaf senescence”
Link to the doctoral thesis: urn:nbn:se:umu:diva-147700
Are you interested to read more? Have a look on the comic strip made by Neil E. Robbins II. He illustrated the results from the article Law et al., 2018 (Plant Physiology) that is included in Daria Chrobok’s thesis. The comic explains very nicely the metabolic adjustments during the different dark treatments:
Simon R Law, Daria Chrobok, Marta Juvany, Nicolas Delhomme, Pernilla Lindén, Bastiaan Brouwer, Abdul Ahad, Thomas Moritz, Stefan Jansson, Per Gardestrom, Olivier Keech (Plant Physiology) 2018; DOI: https://doi.org/10.1104/pp.18.00062
Title: Darkened leaves use different metabolic strategies for senescence and survival
The registration to the UPSC Days 2018 is now open! They will take place on September 6-7 at Sliperiet on the Konstnärlig Campus in Umeå.
The first day will start with a session about future visions for UPSC and continue after lunch with an update about the most recent changes of the UPSC infrastructures. We will also have a scientific session with 3 minutes flash talks and end the first day with a barbecue that will take place in front of UPSC.
On the second day, Anna-Karin Byström from DC Consulting AB will give a workshop on intercultural communications. This workshop will include seminars giving theoretical background about cultural understanding and the communication process as well as practical exercises and tools to handle and interpret actions and reactions that arise in meetings with people of different backgrounds. We will finish the second day with the lunch.
Location: White boxes, Sliperiet, Konstnärlig campus, Umeå (see on map)
|Day 1 - Thursday, 6th September 2018
|9:30 - 10:00||Registration and coffee|
|10.00 - 10.10||Welcome|
|The future UPSC|
|10.10 - 10.40||
Visions for UCMR (Umeå Centre for Microbial Research)
Bernt Eric Uhlin, UCMR & MIMS, Department of Molecular Biology, Umeå University
|10.40 - 11.35||
Visions for UPSC
Ove Nilsson (director of UPSC), Karin Ljung (prefect of the Department of Forest Genetics and Plant Physiology, SLU) and Stefan Jansson (prefect of the Department of Plant Physiology, Umeå University) will talk about their visions for UPSC.
|11.35 - 12.15||
Chair: Catherine Bellini, Chairmen of the UPSC board
|12.15 - 13.30||Lunch|
|13.30 - 13.50||
The new phenotyping platform at UPSC
Ove Nilsson (director of UPSC)
|13.50 - 14.10||
News from the Bioinformatics platform
Nicolas Delhomme (Manager of the UPSC Bioinformatics platform)
|14.10 - 14.40||Coffee break|
|14.40 - 15.10||
Scientific session with 3 min flash talks (max. 1 slide)
|15.10 - 15.20||
Voting and award presentation
|16.30||Barbecue at the Umeå Plant Science Centre (Please bring your own food and drinks)
|Day 2 - Friday, 7th September 2018|
Intercultural communications workshop
Anna-Karin Byström, Ph.Lic. Organisational Communication and CEO, DC Consulting AB
|9.00 - 9.10||
Brief introduction and presentations
|9.10 - 10.10||
Intercultural communication - introduction to cultural understanding and the communication process
|10.10 - 10.55||Coffee and workshop|
|10.55 - 11.45||
Practical tips concerning communication between people of different backgrounds including practical exercises
|11.45 - 12.00||
Concluding the workshop and shorter reflection
|12.00 - 12.10||
Final conclusion by the organisers
|12.10 - 13.10||Lunch|
On Friday, 18th of May, HalehHayatgheibi successfully defended her PhD thesis. She has worked on lodgepole pine (Pinus contorta), a fast-growing tree that was largely introduced into Sweden in the mid-1960s. One major problem of lodgepole pine trees is that their stems are often bending or even break and this lowers the economic value of the wood. Haleh Hayatgheibi designed breeding strategies to optimize both wood quantity and quality of lodgepole pine to reduce stem bending and breakage.
Haleh Hayatgheibi estimated genetic parameters which determine wood quality and quantity of lodgepole pine. She measured for example the diameter of the stem as parameter for wood quantity and the stiffness of the stem. A higher stiffness might prevent the breakage of the stem when it bends and decrease the economic loss. This feature is especially interesting for Northern Sweden.
Lodgepole pine trees from different origin in Canada were planted in different climatic regions in Northern Sweden, e.g. close to the coast or more inland. Haleh Hayatgheibi compared those trees with each other to see which are best suited for which region in Northern Sweden. Based on her results, she can now recommend tree breeders which lodgepole pine trees have the best prerequisites for which climatic region.
Title of the thesis: “Quantitative genetics of lodgepole pine (Pinus contorta) wood quality traits in Sweden”
Link to the doctoral thesis: http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4836
The public defence took place in Björken at SLU Umeå on Friday, 18thof May 2018. Faculty opponent was Yousry A. El-Kassaby from the Forest Sciences Centre, University of British Columbia, Canada. The supervisor was Harry Xiaming Wu.
Six collaborative projects were selected by external reviewers and are now open for application. The postdoctoral fellows will be recruited at the Umeå Plant Science Centre in Sweden but will spend some time at the collaborating partner institute either in France or in Spain. The goal is to intensify the exchange between the three partners of the INUPRAG cooperation.
The INUPRAG cooperation exists since 2015 and is a collaboration between the Umeå Plant Science Centre(UPSC, Sweden), the National Institute for Agricultural Research(INRA, France) and the Centre for Research in Agricultural Genomics(CRAG, Spain). The goals are to foster joint research projects in plant science between the different partners and to train young scientists through regular exchanges between the partner laboratories.
The six granted postdoctoral projects cover different topics within plant science. All group leaders from UPSC could apply with collaborative projects for the postdoctoral fellowships. Three (?) external referees evaluated all submitted projects and selected the six best, three from Umeå University (Department of Plant Physiology) and three from SLU (Department of Forest Genetics and Plant Physiology).
The granted projects are:
Project 1: Interactions between Plastid and Light Signalling Pathways
Project leaders: Åsa Strand (UPSC) & Elena Monte (CRAG)
Project 2: Regulation of the Master Floral Regulator LEAFY by Ubiquitination through the E3 Ligases UFO and BOP2
Project leaders: Markus Schmid (UPSC), Ove Nilsson (UPSC) & François Parcy (INRA, Grenoble)
Project 3: An evo-devo approach to elucidate the role of PIRIN proteins during non-cell autonomous lignification
Project leaders: Hannele Tuominen (UPSC) and Richard Sibout (INRA, Nantes)
Postdoctoral project 4: Unravelling cluster root emergence in white lupin
Project leaders: Stéphanie Robert (UPSC) & Benjamin Péret (INRA, Montpellier)
Project 5: Cell wall mediated control of differential cell elongation in Arabidopsis hook Development
Project leaders: Rishikesh Bhalerao (UPSC) and Olivier Hamant (ENS, INRA, Lyon)
Project 6: Enabling scale-up of somatic embryogenesis (SE) plant production by physiological analysis of embryos processed in bioreactors and the R&D SE System for harvest
Project leaders: Ulrika Egertsdotter (UPSC) and Marie-Anne Lelu-Walter (INRA, Orleans)
On Friday, 20th of April, Christoffer Johnsson successfully defended his thesis titled “Elucidating the phytohormonal control of xylem development”. He could show in his thesis that the plant hormones auxin and gibberellin are important signals for normal wood development in poplar trees. The public defence took place in P-O Backströms sal at SLU Umeå. Faculty opponent was Andrea Polle from the Buesgen Institut, Georg-August University Göttingen, Germany. His academic supervisor was Urs Fischer.
Link to the doctoral thesis: http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-4828
You can find more background information about Christoffer Johnsson’s work here (in Swedish):