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. While vertically transmitting corals inherit symbionts directly from parental colonies, the extent to which symbiont cellular traits are conserved across 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 genus and differed between 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 and Durusdinium 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, providing a mechanistic basis for symbiosis stability.