Table_3_Host and Symbionts in Pocillopora damicornis Larvae Display Different Transcriptomic Responses to Ocean Acidification and Warming.DOCX

As global ocean change progresses, reef-building corals and their early life history stages will rely on physiological plasticity to tolerate new environmental conditions. Larvae from brooding coral species contain algal symbionts upon release, which assist with the energy requirements of dispersal and metamorphosis. Global ocean change threatens the success of larval dispersal and settlement by challenging the performance of the larvae and of the symbiosis. In this study, larvae of the reef-building coral Pocillopora damicornis were exposed to elevated pCO2 and temperature to examine the performance of the coral and its symbionts in situ and better understand the mechanisms of physiological plasticity and stress tolerance in response to multiple stressors. We generated a de novo holobiont transcriptome containing coral host and algal symbiont transcripts and bioinformatically filtered the assembly into host and symbiont components for downstream analyses. Seventeen coral genes were differentially expressed in response to the combined effects of pCO2 and temperature. In the symbiont, 89 genes were differentially expressed in response to pCO2. Our results indicate that many of the whole-organism (holobiont) responses previously observed for P. damicornis larvae in scenarios of ocean acidification and warming may reflect the physiological capacity of larvae to cope with the environmental changes without expressing additional protective mechanisms. At the holobiont level, the results suggest that the responses of symbionts to future ocean conditions could play a large role in shaping success of coral larval stages.

随着全球海洋变化的不断推进，构筑珊瑚礁的珊瑚及其早期生命历史阶段将依赖生理可塑性以适应新的环境条件。产卵珊瑚种类的幼虫在释放时携带有藻类共生体，这些共生体有助于幼虫在扩散和变态过程中的能量需求。全球海洋变化通过挑战幼虫及其共生体的表现，威胁了幼虫扩散和定殖的成功。在本研究中，我们选取了珊瑚礁构建珊瑚 Pocillopora damicornis 的幼虫，将其暴露于增高的 pCO2 和温度条件下，以在原位考察珊瑚及其共生体的表现，并深入理解其对多种胁迫因素的生理可塑性和抗胁迫机制。我们生成了一种从头开始的全共生体转录组，包含珊瑚宿主和藻类共生体的转录本，并通过生物信息学方法将其组装成宿主和共生体组分，以便进行后续分析。在 pCO2 和温度的共同作用下，有十七个珊瑚基因表现出差异表达。在共生体中，有 89 个基因对 pCO2 的变化表现出差异表达。我们的结果表明，许多先前在海洋酸化和变暖情景下观察到的 P. damicornis 幼虫的全共生体反应可能反映了幼虫应对环境变化的生理能力，而无需表达额外的保护机制。在共生体层面上，研究结果暗示，共生体对未来海洋条件的反应可能在塑造珊瑚幼虫阶段的成功中扮演重要角色。