Thomas Wichard: Bacteria-induced morphogenesis in macroalgae: the sea lettuce Ulva only gets into shape with the right bacteria

Special Seminar

  • Datum: 23.07.2018
  • Uhrzeit: 11:00 - 12:00
  • Vortragende(r): Thomas Wichard
  • Friedrich-Schiller-Universität Jena, Institut für Anorganische und Analytische Chemie
  • Ort: MPIPZ
  • Raum: SR II
  • Gastgeber: Miltos Tsiantis
Thomas Wichard: Bacteria-induced morphogenesis in macroalgae: the sea lettuce <i>Ulva </i>only gets into shape with the right bacteria


The extreme environmental plasticity of green macro algal morphogenesis will be discussed in the context of environmental drivers and symbiont-dependent development. The cosmopolitan sea lettuce Ulva (Chlorophyta) is among the most abundant macro algae growing predominantly in intertidal zones. The dramatic increase in Ulva biomass on beaches worldwide is of growing concern. Proliferation and morphogenesis of Ulva depend on the interaction with specifically associated bacteria and the compounds they produce. Under axenic conditions, Ulva develops into callus-like structures, which is mainly characterised by atypical cell wall formation, no cell differentiation, and slow growth. Upon addition of the two bacterial strains, Roseovarius sp. MS2 and Maribacter sp. MS6, a tripartite community is formed, and the morphogenesis of U. mutabilis completely recovers. The tripartite system, as well as the new genetic tool-kit, are the keys to reproducible studies and the understanding of a unique cross-kingdom cross-talk using Ulva as a model system. By analysing Ulva’s chemosphere through metabolomic profiling and bioassay guided purification, the following compounds that are relevant to the cross-kingdom interactions were identified: (1) the algal morphogen thallusin that is produced by bacteria, (2) the bacterial chemo-attractant dimethylsulfoniumpropionate, and (3) the carbon source glycerol, which are both released by Ulva. Moreover, the bacterial quorum sensing signals (N-acyl homoserine lactones) and metallophores were identified in the chemosphere. Deciphering the bacteria induced morphogenesis can thus shed light on the transition from simple to complex multicellularity and will provide additional information about the evolution of the green lineage.


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