New Insights From Transcriptomic Data Reveal Differential Effects of CO2 Acidification Stress on Photosynthesis of an Endosymbiotic Dinoflagellate in hospite

Ocean acidification (OA) has both detrimental as well beneficial effects on marine life; it negatively affects calcifiers while enhancing the productivity of photosynthetic organisms. To date, many studies have focused impacts OA calcification in reef-building corals, a process particularly susceptible to acidification. However, little is known about their algal partners, with some suggesting potential benefits for symbiont productivity. Here, we investigated transcriptomic response endosymbiont Symbiodinium microadriaticum (CCMP2467) Red Sea coral Stylophora pistillata subjected different long-term (2 years) treatments (pH 8.0, 7.8, 7.4, 7.2). Transcriptomic analyses revealed that symbionts from corals under lower pH responded by increasing expression genes related photosynthesis and carbon-concentrating mechanisms. These processes were mostly up-regulated associated metabolic pathways significantly enriched, an overall positive effect photosynthesis-related genes. test this conclusion physiological level, analyzed symbiont’s photochemical performance across treatments. contrast suggested observed gene changes, found significant impairment p CO 2 . Collectively, our data suggest over-expression not but rather acclimation holobiont water chemistries. Our study highlights complex ocean these symbiotic organisms role host determining performance.