海洋硅藻贡献了全球约20%的初级生产力。研究硅藻适应海洋变暖的能力将增进我们对海洋生物地球化学循环的理解及帮助我们预测变暖对海洋生态系统的影响。已有研究发现真核浮游植物硅藻基因组加倍的多倍体化现象，并推测多倍体化在硅藻基因组进化及环境适应中可能具有重要意义。但是尚缺乏合适的多倍体化材料来系统研究硅藻多倍体化在升温适应中的功能及进化机制。申请人前期在温度变化下偶然获得细胞体积显著增大的假微型海链藻多倍体材料，发现它们在高温下生长加快、光合作用增强、色素增多、竞争力增强。在此研究基础上，本项目拟结合生理生化、单培养与竞争培养、短期与长期培养、转录组测序与文献数据分析等方法，以期揭示硅藻多倍体化对温度变化的偏好性、海洋表层水温与硅藻自然种群基因组多倍体化间的关系、以及阐明多倍体化在假微型海链藻升温适应中的功能与进化机制，为深入理解浮游植物升温适应提供理论依据。

Diatoms are responsible for about 20% of global primary productivity. Investigation the adaptive capability of phytoplankton to ocean warming is essential for us to understand marine biogeochemical cycles and predict effect of warming on marine ecosystems. Although studies have confirmed that the polyploidization in diatoms and speculated that polyploidization may play an important role in genome evolution and environmental adaptation. However, it is still lacking a suitable polyploid material to investigate the function and evolutionary mechanisms of diatoms adapting to warming. Here, we previously accidentally obtained a polyploid material of a marine diatom Thalassiosira pseudonana with significantly increased cell volume under temperature stress conditions. We found that polyploid cells show faster growth rate, robust photosynthetic activity, more pigment content and better competitive advantage especially under high temperature. On the basis of above results, we will integrate physiological and biochemical, single cultivation and competitive cultivation, short-term and long-term cultivation, transcriptomic and literature data analysis. The ultimate goal of this analysis is to eventually clarify the preferred temperature conditions of the polyploidization, the relations between ocean surface temperatures and distribution of diatoms with different genome size, and its roles in the function and evolutionary mechanisms adapting to warming. This study can provide us a theoretical basis for understanding the mechanism of adaptive evolution of phytoplankton under global warming.