Morphogenesis of Ulva mutabilis (Chlorophyta) induced by Maribacter species (Bacteroidetes, Flavobacteriaceae)


Growth and morphogenesis of the sea lettuce Ulva (Chlorophyta) depends on the combination of regulative morphogenetic compounds released by specific associated bacteria. Axenic Ulva gametes develop parthenogenetically into callus-like colonies consisting of undifferentiated cells without normal cell walls. In Ulva mutabilis Føyn, two bacterial strains, Maribacter sp. strain MS6 and Roseovarius strain MS2, can restore the complete algal morphogenesis forming a tripartite symbiotic community. Morphogenetic compounds (=morphogens) released by the MS6-strain induce rhizoid formation and cell wall development in U. mutabilis, while several bacteria of the Roseobacter clade, including the MS2-strain, promote blade cell division and thallus elongation. In this study, 12 type strains of the Flavobacteriaceae family, including six Maribacter strains, were examined for their morphogenetic activity in comparison to the original MS6-strain isolated from U. mutabilis. The bioassay is based on the functional complementation of the tested Flavobacteriaceae strain with the Roseovarius MS2-strain. If the test-strain possesses morphogenetic activity complementary to the factor of the MS2-strain, the complete morphogenesis of U. mutabilis can be restored. This bioassay revealed not only the stand-alone activity of certain bacteria, but also their essential capability to take part in the orchestrated bacteria-induced morphogenesis of U. mutabilis. All Maribacter type strains isolated from Ulva could phenocopy the MS6-strain, whereas some distantly related Flavobacteriaceae and a Maribacter strain isolated from a red alga did not possess any activity.

Keywords: bacteroidetes; cell differentiation; green macroalga; morphogens; thallusin


DOI: 10.1515/bot-2016-0083

Projects: A1

Journal: Walter de Gruyter GmbH


Date Published: No date defined

Authors: Thomas Wichard, Anne Weiss, R. Costa

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Weiss, A., Costa, R., & Wichard, T. (2017). Morphogenesis of Ulva mutabilis (Chlorophyta) induced by Maribacter species (Bacteroidetes, Flavobacteriaceae). Botanica Marina, 60(2).

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Created: 10th Jul 2017 at 09:01

Last updated: 10th Jul 2017 at 09:02

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