Huang Wen, Yang Enguang, Yu Kefu, Meng Linqing, Wang Yonggang, Liang Jiayuan, Huang Xueyong, Wang Guanghua
Guangxi Laboratory on the Study of Coral Reefs in the South China Sea, Coral Reef Research Center of China, School of Marine Sciences, Guangxi University, Nanning, China.
Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, China.
Mol Ecol. 2022 Oct;31(20):5339-5355. doi: 10.1111/mec.16662. Epub 2022 Aug 25.
As high temperature stress due to climate change threatens tropical corals, cooler areas at relatively high latitudes may be potential refuges. Tolerance to low temperatures is critical in determining whether corals can successfully migrate to higher latitudes. However, the physiological and molecular adaptations that protect corals from low temperature stress are unclear. In this study, scleractinian Porites lutea samples from the tropical Xisha Islands (XS) and subtropical Daya Bay (DY) in the South China Sea were subjected to a reduction in ambient temperature from 26 to 12°C. Differences in physiological changes and gene expression were analysed. P. lutea from both XS and DY exhibited physiological bleaching under low temperature stress, and the Symbiodiniaceae density, Fv/Fm, and chlorophyll-α content were significantly reduced. Symbiosome antioxidative stress and metabolic enzyme activity first increased and then decreased. RNA-seq analysis showed that the host responded to low temperature stress by activating immune, apoptotic, and autophagic pathways and reducing metabolic levels. Nevertheless, Symbiodiniaceae lacked the physiological regulatory capacity to adapt to low temperatures. The lower cold tolerance of XS tropical P. lutea may attribute to lower oxidative stress resistance, lower photosynthetic capacity, worse energy supply, and higher susceptibility to bacterial and viral infections and diseases in XS corals. The difference in cold tolerance may result from genetic differences between the geographic populations and is possibly detrimental to the migration of tropical coral to relatively high latitude refuges. This study provides a theoretical basis for anthropogenically assisted coral migration as a response to global change.
由于气候变化导致的高温胁迫威胁着热带珊瑚，相对高纬度的较凉爽地区可能是潜在的避难所。对低温的耐受性对于确定珊瑚能否成功迁移到更高纬度至关重要。然而，保护珊瑚免受低温胁迫的生理和分子适应机制尚不清楚。在本研究中，对采自中国南海热带西沙群岛（XS）和亚热带大亚湾（DY）的石珊瑚黄孔珊瑚样本进行环境温度从26°C降至12°C的处理。分析了生理变化和基因表达的差异。来自XS和DY的黄孔珊瑚在低温胁迫下均出现生理白化现象，共生藻密度、Fv/Fm和叶绿素α含量均显著降低。共生体抗氧化应激和代谢酶活性先升高后降低。RNA测序分析表明，宿主通过激活免疫、凋亡和自噬途径并降低代谢水平来应对低温胁迫。然而，共生藻缺乏适应低温的生理调节能力。XS热带黄孔珊瑚较低的耐寒性可能归因于其较低的抗氧化应激能力、较低的光合能力、较差的能量供应以及对XS珊瑚中细菌和病毒感染及疾病的较高易感性。耐寒性的差异可能源于地理种群之间的遗传差异，这可能对热带珊瑚向相对高纬度避难所的迁移产生不利影响。本研究为作为应对全球变化的人为辅助珊瑚迁移提供了理论依据。
