Hijacking and integration of algal plastids and mitochondria in a polar planktonic host

• DOI: 10.1016/j.cub.2025.03.076
• Publication Date: 2025-04-17T14:34:03Z
• Authors: Ananya Kedige Rao; Daniel Yee; Fabien Chevalier; Charlotte LeKieffre; Marie Pavie; Marine Olivetta; Omaya Dudin; Benoit Gallet; Elisabeth Hehenbe...; Mehdi Seifi; Florian Jug; Joran Deschamps; Ting-Di Wu; Rebecca Gast; Pierre-Henri Jouneau; Johan Decelle

In oceanic plankton, various hosts are capable of engulfing and temporarily integrating microalgae (photosymbiosis) or just their photosynthetic plastids (kleptoplastidy) from the environment. These cellular interactions have been hypothesized to be representative evolutionary steps in plastid acquisition eukaryotes, but underlying mechanisms not fully understood. Here, we studied a polar kleptoplastidic dinoflagellate, which is known steal microalga Phaeocystis antarctica. We tracked morphology activity stolen over several months by combining multimodal subcellular imaging photophysiology. Upon integration inside host vacuole, volume pyrenoids significantly increased, was boosted. This may supported retention 50-fold larger algal nucleus for ∼1 week. Once lost, there decrease photosynthesis, nucleus- plastid-encoded photosystem subunits were still detected. Carbon fixation transfer also maintained after >2 months. showed that mitochondrion retained months, transforming into an extensive network interacting with plastids. highlights complex strategy plankton along continuum symbioses, where both mitochondria hijacked without nucleus. association, found widely distributed regions, suggests plastid-mitochondrion interaction played role evolution opens new questions about control organelle maintenance.