Selective conservation of symbiont cell-surface glycans across generations in a vertically transmitting coral

Coral resilience under climate change depends on the stability of coral–Symbiodiniaceae symbioses. Vertically transmitting corals inherit symbionts directly from parental colonies, yet the extent to which symbiont cellular traits are conserved across host life stages remains unclear. Here, we examined cell-surface glycan profiles of Symbiodiniaceae in parental colonies and eggs of the coral Montipora capitata. Glycan signatures were structured by symbiont species and differed between coral life stages, with mannose/glucose- and galactose-containing glycoproteins as primary drivers of variation. Despite life-stage differences, parent–offspring comparisons revealed significant conservation of glycan profiles, indicating intergenerational transmission of symbiont cellular traits that differed between Cladocopium C31 and Durusdinium glynnii and were driven by distinct glycan classes. These results suggest that vertical transmission preserves key recognition-relevant glycans while allowing flexibility in other symbionts’ surface traits, consistent with a role in maintaining symbiosis stability.