海生高等植物鳗草和日本鳗草抗氧化系统对高温胁迫的响应特征差异及机制研究

海生高等植物海草具有独特的进化地位和重要的生态价值，全球气候变化导致的高温胁迫是海草面临的重要威胁，影响其关键生理过程、个体存活乃至种群分布。抗氧化系统对于海草抵御高温胁迫至关重要，并且存在显著的种间差异。本研究以我国北方代表性海草物种鳗草(Zostera marina)和日本鳗草(Zostera japonica)为研究对象，以抗氧化系统为切入点，综合运用生理生化分析结合多组学技术手段，阐明两种海草响应高温胁迫的分子机制。开展生化检测研究海草活性氧累积与氧化损伤；通过转录组及miRNA组分析确定差异表达基因并验证；基于蛋白质组分析抗氧化系统相关蛋白的表达差异；从基因转录水平和蛋白翻译水平整体解析抗氧化系统关键基因响应高温胁迫的机制与途径；对比分析两种海草种间响应特征差异和分子机制。研究结果将为阐明全球变化背景下海草种群变化机制提供理论依据，有助于分析我国北方海草群落结构及分布的演变过程。

Seagrasses are of immense ecological and evolutionary significances in marine ecosystems. They are the only group of angiosperms that evolved from terrestrial environments to marine and have adapted successfully to marine environments forming productive and species-rich habitats in coastal areas throughout the world. The increase in the incidence of summer extreme high temperature events, e.g. marine heatwaves, associated to the ongoing global climate change severely affects physical processes of seagrasses and eventually threatens their survival by causing the accumulation of reactive oxygen species (ROS) in the plants. The antioxidant defense mechanisms of seagrasses play a pivotal role in the thermal stress response by counterbalancing the ROS accumulation to protect plants from oxidative damage. The results of previous studies suggested that there are interspecific differences between various seagrass species in the sensitivity to thermal stress, and therefore increased temperature will differently impact seagrass meadows depending on the species. In this study we aimed to analyze the thermal stress responses of the seagrasses Zostera marina and Zostera japonica under controlled conditions. To gain better understanding of thermal tolerance mechanisms in the two species of seagrasses an integrated physiological, transcriptomics and comparative proteomic analysis will be carried out. The degree of ROS accumulations and oxidative damages of two different seagrasses will be tested through physiological investigations. The overall gene expression response of Z. marina and Z. japonica will be investigated by transcriptomic and microRNAomic analysis. To improve the understanding of the molecular mechanism of differential thermal tolerance in different species the interspecific differences in response features, processes and mechanisms of antioxidant systems will be contrastively analyzed. This study can reveal the responses characteristics and mechanisms of antioxidant systems in Z. marina and Z. japonica and demonstrate the molecular mechanisms of interspecific differences. The results of this study will provide a theoretical basis for the prediction of population fate of seagrass under global warming from a new perspective of plant antioxidant capacity, and therefore be useful to speculating upon changes of distribution and composition of seagrass communities in north China.