Symbiodinium Functional Diversity in the Coral Siderastrea siderea Is Influenced by Thermal Stress and Reef Environment, but Not Ocean Acidification
Symbiodinium Functional Diversity in the Coral Siderastrea siderea Is Influenced by Thermal Stress and Reef Environment, but Not Ocean Acidification
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DOI：
10.3389/fmars.2018.00150
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发表时间：
2018-04-30
影响因子：
3.7
通讯作者：
Castillo, Karl D.
中科院分区：
文献类型：
--
作者：
Davies, Sarah W.;Ries, Justin B.;Castillo, Karl D.
珊瑚漂白事件的频率越来越高，要求检查的生理和分子反应的石珊瑚和藻类共生体（共生藻属）。与漂白有关的压力源。在这里，我们量化的长期（95天）的热和CO2酸化应力的光化学效率的影响，在hospite共生藻内的珊瑚Siderastrea siderea，沿着与相应的珊瑚颜色强度，珊瑚从两个珊瑚礁区（forereef，近岸）的中美洲大堡礁系统。然后，我们探索的分子反应，在hospite共生藻这些压力通过全基因组基因表达谱。升高的温度降低共生体的光化学效率和高度相关的珊瑚颜色损失。然而，前礁共生体的光化学效率更负面的热应力比近岸共生体的影响，这表明更大的耐热性和/或减少光损伤近岸珊瑚。在控制温度下，CO2酸化共生体的生理影响不大，虽然forefreef共生体表现出组成较高的光化学效率比近岸共生体。基因表达谱分析显示，S。在高温胁迫下，侧沟共生甲藻（Symbiodinium goreaui，C1）向耐热共生甲藻（Symbiodinium trenchii，D1 a）转化。比较宿主和共生体中保守基因的转录组学发现，很少有差异表达的S。goreaui基因与S. siderea，突出了宿主在珊瑚对环境压力的反应中的作用。虽然S. goreaui转录组对酸化胁迫的响应没有变化，其基因表达强烈依赖于礁带，forereef S. goreaui，表现出与光合作用相关的基因的富集。这一发现，加上组成较高的前礁S。goreaui光化学效率表明，与初级生产有关的基因的功能差异存在于珊瑚礁区之间。
Coral bleaching events are increasing in frequency, demanding examination of the physiological and molecular responses of scleractinian corals and their algal symbionts (Symbiodinium sp.) to stressors associated with bleaching. Here, we quantify the effects of long-term (95-day) thermal and CO2-acidification stress on photochemical efficiency of in hospite Symbiodinium within the coral Siderastrea siderea, along with corresponding coral color intensity, for corals from two reef zones (forereef, nearshore) on the Mesoamerican Barrier Reef System. We then explore the molecular responses of in hospite Symbiodinium to these stressors via genome-wide gene expression profiling. Elevated temperatures reduced symbiont photochemical efficiencies and were highly correlated with coral color loss. However, photochemical efficiencies of forereef symbionts were more negatively affected by thermal stress than nearshore symbionts, suggesting greater thermal tolerance and/or reduced photodamage in nearshore corals. At control temperatures, CO2-acidification had little effect on symbiont physiology, although forereef symbionts exhibited constitutively higher photochemical efficiencies than nearshore symbionts. Gene expression profiling revealed that S. siderea were dominated by Symbiodinium goreaui (C1), except under thermal stress, which caused shifts to thermotolerant Symbiodinium trenchii (D1a). Comparative transcriptomics of conserved genes across the host and symbiont revealed few differentially expressed S. goreaui genes when compared to S. siderea, highlighting the host's role in the coral's response to environmental stress. Although S. goreaui transcriptomes did not vary in response to acidification stress, their gene expression was strongly dependent on reef zone, with forereef S. goreaui exhibiting enrichment of genes associated with photosynthesis. This finding, coupled with constitutively higher forereef S. goreaui photochemical efficiencies, suggests that functional differences in genes associated with primary production exist between reef zones.