The Max Planck Institute for Molecular Plant Physiology hosts weekly seminars with guest speakers from all over the world.

Seminars usually take place wednesdays between 2 pm and 3.30 pm in the seminar room (1.052 and 1.053) in the central building, but exceptions prove the rule. All times, dates and topics can be found here.

Ben Field - An unusual nucleotide is a potent controller of chloroplast function that regulates plant growth and development

The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained surprisingly elusive. I will present our findings in the model plant Arabidopsis thaliana where we recently showed that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We were also able to demonstrate that the antagonistic functions of different plant RelA SpoT homologs (RSHs) together modulates ppGpp levels to regulate chloroplast function, and RSHs are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Together our results strongly suggest that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development. [more]

Shizue Matsubara - Long-term acclimation of Arabidopsis to highly fluctuating light environment

Natural light environment is highly variable in both intensity and spectral quality. The light intensity can vary between zero (night) and >2000 μmol photons m-2 s-1 (full sunlight) as the earth rotates, weather changes and wind moves branches and leaves. Upon sudden and large increase in light intensity, photosynthesis is limited biochemically, e.g. by the activation state of RubisCO and the availability of the Calvin-Benson cycle intermediates or inorganic phosphate for ATP synthesis. Low stomatal conductance may also limit plant’s capacity to utilize additional light energy for photosynthesis. When put under highly fluctuating light conditions for days, Arabidopsis plants primarily or initially downregulate photosynthetic light harvesting and linear electron transport while upregulating photoprotection at the expense of carbon gain and growth. Towards understanding the mechanisms of long-term acclimation to highly fluctuating light environment, we studied leaf transcriptome, metabolome and proteome of Arabidopsis (Columbia wild type). Plants were exposed to highly fluctuating light or constant light condition for 3 or 7 days to focus on long-lasting (non-transient) acclimatory changes and downstream responses that may give rise to the phenotypic alterations. Given the pronounced diurnal and circadian variations in leaf metabolism and gene expression, samples were taken at two contrasting time points during the light period in the 12 h/12 h light/dark cycle, namely, early morning and at the end of the day. Furthermore, young and mature leaves were analyzed separately as they typically differ in the photosynthetic capacity. Overall, our results underscore photo-oxidative stress responses and mitigation of acceptor-side limitation to photosynthesis during acclimation to highly fluctuating light. The gene expression profiles revealed distinct responses of young and mature leaves in the morning and at the end of the day, indicating crosstalk between long-term acclimation, leaf development and circadian clock. In particular, I will highlight the changes related to the components of photosynthesis and photoprotection. [more]

Sandra Kerbler - Unravelling the mitochondrial electron transport chain in the cold: is ATP synthase the key?

  • Date: Mar 17, 2017
  • Time: 14:00 - 15:30
  • Speaker: Sandra Kerbler
  • Location: Box
  • Room: 0.21
  • Host: Mark Stitt


March 2017

Keiko Sugimoto - Epigenetic control of plant cell reprogramming

Many plant species display remarkable developmental plasticity and regenerate new organs after injury. Local signals produced by wounding are thought to trigger organ regeneration but molecular mechanisms underlying this control remain largely unknown1,2. We have previously identified a group of AP2/ERF transcription factors named WOUND INDUCED DEDIFFERENTIATION1-4 (WIND1-4) as central regulators of wound-induced cellular reprogramming in plants3. More recently we demonstrated that WIND1 promotes shoot regeneration by directly up-regulating ENHANCER OF SHOOT REGENERATION1 (ESR1) encoding another AP2/ERF transcription factor in Arabidopsis4. We have also shown that some of WIND genes and other developmental regulators need to be epigenetically repressed by POLYCOMB REPRESSIVE COMPLEX 2 to prevent unscheduled cellular reprogramming in intact plants5,6. In this talk I will discuss our latest findings on how WIND proteins promote cellular reprogramming and how wound stress activates the WIND-mediated pathway by overriding epigenetic repression. [more]

Karen B. Barnard-Kubow - Patterns of organelle inheritance and genome evolution: characterizing the evolutionary dynamics of a cytonuclear incompatibility

Negative interactions between the organelle and nuclear genomes (cytonuclear incompatibility) are thought to be among the early genetic incompatibilities to arise during speciation. While there are now several good examples of cytonuclear incompatibility leading to reproductive isolation within and between closely related species, there are still many unanswered questions regarding the evolutionary dynamics of cytonuclear incompatibility. Using the herbaceous species Campanulastrum americanum, I examine how patterns of organelle inheritance and rates of organelle genome evolution may both facilitate and constrain the evolution of cytonuclear incompatibility and its ability to drive the early stages of speciation. [more]

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