Colonization and metabolite profiles of homologous, heterologous and experimentally evolved algal symbionts in the sea anemone Exaiptasia diaphana

Sarah Jane Tsang Min Ching; Wing Yan Chan; Alexis Perez-Gonzalez; Katie E Hillyer; Patrick Buerger; Madeleine J H van Oppen

doi:10.1038/s43705-022-00114-7

Colonization and metabolite profiles of homologous, heterologous and experimentally evolved algal symbionts in the sea anemone Exaiptasia diaphana

ISME Commun. 2022 Mar 30;2(1):30. doi: 10.1038/s43705-022-00114-7.

Authors

Sarah Jane Tsang Min Ching^#¹, Wing Yan Chan^#², Alexis Perez-Gonzalez^{3

4}, Katie E Hillyer⁵, Patrick Buerger^{1

6}, Madeleine J H van Oppen^{1

7}

Affiliations

¹ School of BioSciences, University of Melbourne, Parkville, VIC, Australia.
² School of BioSciences, University of Melbourne, Parkville, VIC, Australia. w.chan@unimelb.edu.au.
³ Melbourne Cytometry Platform, University of Melbourne, Parkville, VIC, Australia.
⁴ Department of Microbiology and Immunology, The University of Melbourne, at The Peter Doherty Institute of Infection and Immunity, Parkville, VIC, Australia.
⁵ CSIRO Land and Water, Dutton Park, Brisbane, QLD, Australia.
⁶ Applied Biosciences, Macquarie University, North Ryde, NSW, Australia.
⁷ Australian Institute of Marine Science, Townsville, QLD, Australia.

^# Contributed equally.

Abstract

The sea anemone, Exaiptasia diaphana, is a model of coral-dinoflagellate (Symbiodiniaceae) symbiosis. However, little is known of its potential to form symbiosis with Cladocopium-a key Indo-Pacific algal symbiont of scleractinian corals, nor the host nutritional consequences of such an association. Aposymbiotic anemones were inoculated with homologous algal symbionts, Breviolum minutum, and seven heterologous strains of Cladocopium C1^acro (wild-type and heat-evolved) under ambient conditions. Despite lower initial algal cell density, Cladocopium C1^acro-anemeones achieved similar cell densities as B. minutum-anemones by week 77. Wild-type and heat-evolved Cladocopium C1^acro showed similar colonization patterns. Targeted LC-MS-based metabolomics revealed that almost all significantly different metabolites in the host and Symbiodiniaceae fractions were due to differences between Cladocopium C1^acro and B. minutum, with little difference between heat-evolved and wild-type Cladocopium C1^acro at week 9. The algal fraction of Cladocopium C1^acro-anemones was enriched in metabolites related to nitrogen storage, while the host fraction of B. minutum-anemones was enriched in sugar-related metabolites. Compared to B. minutum, Cladocopium C1^acro is likely slightly less nutritionally beneficial to the host under ambient conditions, but more capable of maintaining its own growth when host nitrogen supply is limited. Our findings demonstrate the value of E. diaphana to study experimentally evolved Cladocopium.