基于内源性海藻糖及其合成途径多样性探索珊瑚抵御环境温度变化的潜在机制

Trehalose was widely reported to have non-specific protective effects on organisms against environmental change. The new study proved that trehalose could affect the specific selection and establishment of microbial symbionts for coral larvae as a chemical attractant. We speculate that trehalose is not only as a chemical attractant in the coral reef ecosystem but also possesses the biological functions to assist coral resisting environment temperature changes (high or low temperature). Besides, the different trehalose synthesis pathways in coral symbiont affect the accumulation efficiency of trehalose, and then decide the tolerance ability of coral with temperature changes. Therefore, we intend to study the different species of stony coral from Weizhou Island. Firstly, the specificity and abundance of trehalose synthesis pathways will be identified in coral symbiont using metagenomic and degenerate PCR. Secondly, the tolerance ability of coral against temperature changes and the accumulation efficiency of endogenous trehalose in coral symbiont will be analyzed. Finally, the relationship among tolerance, accumulation efficiency, and synthesis pathways will be analyzed. We expect to explore the potential mechanisms of coral response to environment temperature changes based on the synthesis pathway and accumulation efficiency of trehalose. These results will provide some scientific basis and new research ideas for studying the genetic evolution and bleaching death of coral reef.

海藻糖被广泛证实对生命有机体应激环境变化具有非特异性保护作用。新的研究证实海藻糖作为一种化学引诱物影响珊瑚浮浪幼虫特异性选择和建立微生物共生体。我们推测海藻糖在珊瑚礁生态系统中不仅仅是作为一种化学引诱物，它还具有协助珊瑚抵御环境温度变化（高温或者低温）的生物学功能，并且其在珊瑚体内的积累效率受合成途径影响，进而决定珊瑚应对温度变化的耐受能力。我们拟以涠洲岛不同类型的石珊瑚为材料：1.利用宏基因组与简并PCR技术鉴定珊瑚共生体中存在的海藻糖合成途径的类型及丰度；2.室内模拟研究珊瑚耐受温度变化的能力及其内源性海藻糖的积累效率；3.分析珊瑚应对温度变化的耐受能力、内源性海藻糖积累效率及其合成途径三者之间的相互关系。预期从海藻糖的合成途径到积累效率探索不同类型珊瑚应对环境温度变化的耐受能力不同的潜在机制，为研究珊瑚礁种群多样性的演化规律和白化死亡机理提供科学依据和新的研究思路。

全球气候变暖和人类活动加剧导致全球珊瑚礁出现严重退化。了解珊瑚对异常环境变化的适应机理以及未来演化趋势已成为重点关注的科学问题。整体上，项目围绕造礁石珊瑚对环境适应性的微生态机理，重点分析了南海不同类型珊瑚中共生微生物的生态特征与珊瑚宿主对环境的适应性；珊瑚共生功能固氮微生物生态特征与珊瑚宿主环境适应性的关系；南海大尺度范围珊瑚对不同环境的适应性与共生微生物的关联性；室内模拟实验解析珊瑚共生体（细菌和虫黄藻）对高温胁迫的响应模式。研究结果得出珊瑚共生微生物的高多样性、特殊类群（耐热型虫黄藻、特异性的固氮菌和光合细菌）是珊瑚适应环境变化的基础，同时也是珊瑚对极端环境耐受性不同的原因之一，为深入研究南海珊瑚适应全球变化的潜力提供科学依据。

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