Dinophyceae use exudates as weapons against the parasiteAmoebophryasp. (Syndiniales)

Abstract

SummaryParasites of the genus Amoebophrya sp. are important contributors to marine ecosystems and can be determining factors in the demise of blooms of Dinophyceae, including microalgae commonly responsible for toxic red tides. Yet they rarely lead to the total collapse of Dinophyceae blooms. The addition of resistant Dinophyceae (Alexandrium minutum or Scrippsiella donghaienis) or their exudate into a well-established host-parasite culture (Scrippsiella acuminata-Amoebophrya sp.) mitigated the success of the parasite and increased the survival of the sensitive host. Effect were mediated via water-borne molecules without the need of a physical contact. Severity of the anti-parasitic defenses fluctuated depending on the species, the strain and its concentration, but never totally prevented the parasite transmission. The survival time of Amoebophrya sp. free-living stages (dinospores) decreased in presence of A. minutum but not of S. donghaienis. The progeny drastically decreased with both species. Integrity of the membrane of dinospores was altered by A. minutum which provided a first indication on the mode of action of these anti-parasitic molecules. These results demonstrate that extracellular defenses are an effective strategy against parasites that does not only protect the resistant cells but also have the potential to affect the whole surrounding community.

Chloroplast Ultrastructure and Photosynthetic Response of the Dinoflagellate Akashiwo sanguinea Throughout Infection by Amoebophrya sp.

“…The intrinsic relationship between Amoebophrya and its dinoflagellate host implies a delicate balance. The parasite may subvert host metabolism to fulfill its needs while the host develops strategies to survive from the parasitic infection (Kim and Park, 2016;Scholz et al, 2017;Marc et al, 2021). The developments of Amoebophrya infection are different between the thecate and athecate dinoflagellates, and the two groups show various responses to the parasitic infection (Kim, 2006;Park et al, 2013).…”