Symbiosis, defined as the persistent association between two distinct species, is an evolutionary and ecologically critical phenomenon facilitating survival of both partners in diverse habitats. The biodiversity of coral reef ecosystems depends on a functional symbiosis with photosynthetic dinoflagellates of the highly diverse genus Symbiodinium, which reside in coral host cells and continuously support their nutrition. The mechanisms underlying symbiont selection to establish a stable endosymbiosis in non-symbiotic juvenile corals are unclear. Here we show for the first time that symbiont selection patterns for larvae of two Acropora coral species and the model anemone Aiptasia are similar under controlled conditions. We find that Aiptasia larvae distinguish between compatible and incompatible symbionts during uptake into the gastric cavity and phagocytosis. Using RNA-Seq, we identify a set of candidate genes potentially involved in symbiosis establishment. Together, our data complement existing molecular resources to mechanistically dissect symbiont phagocytosis in cnidarians under controlled conditions, thereby strengthening the role of Aiptasia larvae as a powerful model for cnidarian endosymbiosis establishment.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Funding was provided to A.G. by the Emmy-Noether-Programme of the German Research Foundation (DFG) (grant no. GU 1128/3-1), by a Marie Curie Career Integration Grant (CIG) under the FP7-PEOPLE-2013-CIG program, European Commission, and with financial support through funds for the future concept of Heidelberg University within the Excellence Initiative by German federal and state governments; to I.W. by a PhD fellowship from the Foundation for Science and Technology (FCT, Portugal); and to P.A.V. by a PhD fellowship from the Baden-Wurttemberg Landesgraduiertenforderung Program. Research reported in this publication was supported by King Abdullah University of Science and Technology (KAUST). We thank Steffen Lemke, Thomas Holstein, and Suat Ozbek for advice, comments, and sharing reagents and equipment; and Natascha Bechtoldt and Madeline Bucher for technical help with experiments. We thank the Nikon Imaging Center at the University of Heidelberg, especially Nico Dross for help with microscopy. We also thank members of the Jun Minagawa and Naoto Ueno groups for help with coral larvae collection and maintenance at Sesoko as well as for sharing expertise, equipment, and reagents.