show Abstracthide AbstractThe lichen symbiosis is characterized primarily by the mycobiont-photobiont relationship. The associated mycobiont and photobiont lineages can vary along a lichen's range, and this variation contributes to the holobiont's environmental adaptation. However, little is known about the interaction of these environment-selected symbiont pairings at the molecular level. Here, we explore the effect of symbiont genotype and a light pulse treatment on lichen metatranscription.