Umeå University

  • Thesis Defence: Xylem cells cooperate in the control of lignification and cell death during plant vascular development, Umeå, Sweden

    Xylem cells cooperate in the control of lignification and cell death during plant vascular development

    Xylem cells cooperate in the control of lignification and cell death during plant vascular development

    Escamez, Sacha

    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).ORCID iD: 0000-0001-7049-6978


    2016 (English)Doctoral thesis, comprehensive summary (Other academic)
    Abstract [EN]                
    The evolutionary success of land plants was fostered by the acquisition of the xylem vascular tissue which conducts water and minerals upwards from the roots. The xylem tissue of flowering plants is composed of three main types of cells: the sap-conducting tracheary elements (TE), the fibres which provide mechanical support and the parenchyma cells which provide metabolic support to the tissue. Both the TEs and the fibres deposit thick polysaccharidic secondary cell walls (SCWs), reinforced by a rigid phenolic polymer called lignin. The cell walls of TEs form efficient water conducting hollow tubes after the TEs have undergone programmed cell death (PCD) and complete protoplast degradation as a part of their differentiation. The work presented in this thesis studied the regulation of TE PCD by characterizing the function of the candidate PCD regulator METACASPASE 9 (MC9) in Arabidopsis thaliana xylogenic cell suspensions. These cell suspensions can be externally induced to differentiate into a mix of TEs and parenchymatic non-TE cells, thus representing an ideal system to study the cellular processes of TE PCD. In this system, TEs with reduced expression of MC9 were shown to have increased levels of autophagy and to trigger the ectopic death of the non-TE cells. The viability of the non-TE cells could be restored by down-regulating autophagy specifically in the TEs with reduced MC9 expression. Therefore, this work showed that MC9 must tightly regulate the level of autophagy during TE PCD in order to prevent the TEs from becoming harmful to the non-TEs. Hence, this work demonstrated the existence of a cellular cooperation between the TEs and the surrounding parenchymatic cells during TE PCD. The potential cooperation between the TEs and the neighbouring parenchyma during the biosynthesis of lignin was also investigated. The cupin domain containing protein PIRIN2 was found to regulate TE lignification in a non-cell autonomous manner in Arabidopsis thaliana. More precisely, PIRIN2 was shown to function as an antagonist of positive transcriptional regulators of lignin biosynthetic genes in xylem parenchyma cells. Part of the transcriptional regulation by PIRIN2 involves chromatin modifications, which represent a new type of regulation of lignin biosynthesis. Because xylem constitutes the wood in tree species, this newly discovered regulation of non-cell autonomous lignification represents a potential target to modify lignin biosynthesis in order to overcome the recalcitrance of the woody biomass for the production of biofuels.

    Place, publisher, year, edition, pagesUmeå University, 2016., 76 p.                
    Keyword [EN]                
    Xylem, Arabidopsis, programmed cell death, tracheary element, xylem vessel, autophagy, metacaspase, lignin, secondary cell wall, chromatin, gene expression
    National Category            
    Botany
    Identifiers
    URN: urn:nbn:se:umu:diva-115787ISBN: 978-91-7601-400-4OAI: oai:DiVA.org:umu-115787DiVA: diva2:900504
    Public defence        
    2016-03-04, KB3A9, KBC building, Umeå University, Umeå, 13:00 (English)    
    Opponent    

    Groover, Andrew

    Department of Plant Biology, University of California, Davis, California, USA.

    Supervisors    

    Tuominen, Hannele

    Umeå University, Faculty of Science and Technology, Department of Plant Physiology.



     


     
     
     
     
    Available from:2016-02-12 Created:2016-02-04 Last updated:2016-02-11Bibliographically approved
  • Transformation of Sweden's Energy System Discussed at Luleå in August

    Akkats power station Credit LTUAkkats hydro power station far north in Sweden at Jokkmokk, owned by state-run energy utility Vattenfall. Photo by courtesy of Vattenfall AB.Bio4Energy researchers and industrial partners are calling on energy stakeholders—representatives of Swedish authorities, business and industry, research institutes and academics—to join them 23-24 Augustat Luleå, Sweden, for talks on how far the country has come in implementing a sustainable energy system.

    Summarising the economic, social and environmental side of things, as well as discussing ways forward, does not sound like an easy task to accomplish in two days, but conference coordinator This email address is being protected from spambots. You need JavaScript enabled to view it. believes it can be done.

    "The transformation of the Swedish energy system is a great undertaking and requires a broad start. There will be 50 research presentations and a number of keynote [addresses] by people from industry and authorities and politicians. People can expect to hear about systems' studies, analyses of political support measures, how to promote biofuels and the development of markets and trade", according to Lundmark, who is a professor at the Luleå University of Technology.

    Ibrahim Balyan, Sweden's minister for energy, and Tomas Kåberger, Swedish energy profile and professor at Chalmers University of Technology, are posted as keynote speakers on the website of the Swedish Association for Energy Economics Conference 2016, and the event is subtitled 'Current and future challenges of energy systems in Sweden and neighbouring countries'.
  • Umeå Plant Science Centre 50-year Anniversary Symposium, Umeå, Sweden

    Please see the Bio4Energy Events' page.
  • Umeå Renewable Energy Meeting 2016, Umeå, Sweden

  • Umeå Renewable Energy Meeting, Umeå, Sweden

    UREM 2017
  • Workshop on Regenerated Cellulose & Cellulose Derivatives, Örnsköldsvik, Sweden

    The 7th Workshop on Cellulose

    Regenerated Cellulose and Cellulose Derivatives

    Örnsköldsvik, Sweden, November 15-16, 2016 

    Call for papers

    This 7th semi-annual international workshop is arranged in cooperation betweenUmeå University and Karlstad University and is focused on basic and applied studies in the field of cellulose,nanocellulose, regenerated cellulose and cellulose derivatives. The workshop is sponsored by leading suppliers of dissolving pulps and machinery to guarantee that the workshop will have a mix of academic and applied presentations.

    Topics of interest for submission include, but are not limited to:

    Cellulose chemistry and derivatives

    Cellulose structures and composites

    Dissolution of cellulose

    Dissolving pulp preparation and properties

    Nanocellulose, Regeneration of cellulose

    Spinning of cellulosic fibres

    Deadlines for abstracts

    Abstracts of one A4 page are welcome to This email address is being protected from spambots. You need JavaScript enabled to view it. latest May 30, 2016. If the abstract is accepted extended abstracts of max four A4 pages are welcome until October 31.

    Information

    For more information visit www.celluloseworkshop.com soon to be launched

    or contact: Professor UlfGermgård, email This email address is being protected from spambots. You need JavaScript enabled to view it.

    Tel +46(0)54 70 01 780 or +46(0)70 32 19 584