珊瑚对环境变化响应的内共生调控机制

Collectively called zooxanthellae, photosynthetic dinoflagellates in the genus Symbiodinium are essential coral symbionts encompassing nine phylogenetic clades (A-I). The community composition and diversity of zooxanthellae can fundamentally mediate coral responses to environmental change. For example, Symbiodinium in the clade D is believed to be more thermal tolerant than its counterpart in the clade C, and hence has the potential to convey thermal tolerance to the host coral. Yet, the dynamic processes and molecular mechanisms of symbiont changes underlying distinct coral responses upon environmental cues, remain largely unknown. In this project, we propose to integrate ecological surveys and laboratory controlled experiments that mimic environmental perturbations to elucidate the cellular and molecular mechanism that corals respond to environmental change and ecosystem via endosymbiont regulation. Through investigation on the abundance, spatial-temporal distribution, and molecular systematics of Symbiodinium, combined with transcriptomic study, we intend to further our understanding of how different Symbiodinium genotypes affect coral community and its tolerance to environmental stress. The outcome is predicted to be crucial in addressing the relevance of algal symbiont shuffling as a defensive mechanism for increased coral resilience, which may have implications for coral reef protection and remediation, under future climate change.

虫黄藻是一类与珊瑚共生的光合作用甲藻，在系统进化上包括九大系群（A-I）。虫黄藻的群落组成与多样性可以从根本上调控珊瑚对环境变化的响应。例如，D系群的虫黄藻据信比C系群的更耐热，并有可能将这种热耐受性传递给宿主珊瑚。然而，我们对这种通过内共生体改变来支配珊瑚响应环境变化的动态过程和分子机制知之甚少。本项目拟结合现场生态调查与模拟环境胁迫的室内受控培养实验，从细胞和分子水平诠释珊瑚对环境变化与生态系统响应的内共生调控机制。通过对虫黄藻的时空分布、丰度、以及系统进化多样性研究，结合转录组学分析，我们将了解不同系群虫黄藻如何影响珊瑚群落、进而影响其对环境胁迫的耐受力。研究结果对评估利用共生藻重组作为一种防御机制提高珊瑚的生态韧性具有重要价值，并可为未来全球变化背景下的珊瑚礁保护与修复提供科学参考。

珊瑚-虫黄藻-细菌的互利共生关系对造礁珊瑚钙化和维持珊瑚生态健康至关重要，然而，我们对内共生虫黄藻与细菌系群调控珊瑚宿主响应环境变化的动态过程和分子机制知之甚少。本项目结合现场生态调查与室内受控培养实验，从细胞和分子水平诠释了虫黄藻和细菌群落结构变化和生理表型可塑性对珊瑚响应环境胁迫的影响。通过室内受控模拟实验，厘清了敏感型与耐受型虫黄藻介导珊瑚响应高温及酸化胁迫的生理过程，珊瑚-虫黄藻互作转录组进一步阐明共生体响应环境胁迫的分子机制。通过对共生藻菌群落结构的动态追踪，揭示了特异谱系虫黄藻相关细菌群落转变所介导的珊瑚对高温与海洋酸化的响应，阐明了核心微生物群落、关键指示物种、共生体营养盐循环等对珊瑚健康状况的影响及其调控机制。研究结果强调了珊瑚共生体的表型可塑性，以及珊瑚宿主适应环境胁迫的权衡策略，为全球气候变化背景下珊瑚弹性适应的重塑方式，提供了理论依据。对评估利用共生藻重组作为一种防御机制提高珊瑚的生态韧性具有重要价值，并可为制定合理、可持续性珊瑚礁保护措施供科学参考。