青藏高原草甸土壤病毒对气候暖化的响应特征和演替规律

The alpine grassland of Tibetan Plateau stores approximately 23% of the total soil organic carbon in China, which is an important part of the global carbon cycle. With the continuous climate warming, soil microbial community and carbon and nitrogen cycling in the alpine grassland are increasingly affected. Virus is an important regulator and participant of microbial community and element cycling. However, the research progress of soil viral community is slow, due to the large number of viruses, the high complexity of viral communities and the lack of research methods. The response and succession pattern of soil viral communities under warming is even more poorly explored, especially in the alpine grassland of Tibetan Plateau. In this project, we will collect warmed and control soil samples in the 10th year of continuous warming experiment at the Haibei Alpine Grassland Ecosystem Research Station. Soil microbial metagenome under warming and control treatments will be obtained from four different years by shotgun sequencing and 16S rRNA gene amplicon sequencing of soil samples in the 10th year and previously collected in the 3rd, 5th and 7th years. Through evaluating, integrating and optimizing bioinformatics techniques for virus identification and host recognition, we hope to identify viral community composition and its response characteristics to warming, clarify succession pattern of viral community along time, and reveal the key interaction between viruses and host microorganisms. Combining with plant and soil variables, we also hope to establish the correlation between viral communities and soil carbon and nitrogen components. Consequently, all findings of the experiments will provide the theoretical basis for elucidating the regulation mechanism of viruses on soil carbon and nitrogen cycling under the climate warming scenario.

青藏高原高寒草甸储存了我国约23%的土壤有机碳，是全球碳循环的重要组成部分。随着全球气候持续暖化，青藏高原高寒草甸土壤微生物群落和碳氮循环受到日益严重的影响。病毒是微生物群落和元素循环重要的调节者和参与者。然而，由于病毒数量极多，群落高度复杂以及研究方法的匮乏使得土壤病毒的研究进展缓慢，全球变暖情景下土壤病毒群落的功能响应和演替规律尚未明确。本项目拟依托中国科学院海北站长期连续增温野外试验平台，采集第10年增温和对照土壤样品，结合已有的第3、5、7年土壤样品，通过鸟枪法和16S rRNA基因扩增子测序获取宏基因组数据，评估、集成和优化病毒鉴定和宿主识别的生物信息学技术，明确土壤病毒群落组成及对增温的响应特征，厘清土壤病毒随时间推移的演替规律，解析病毒-宿主微生物的关键互作关系。结合植物和土壤数据，建立病毒群落与土壤碳氮组分的关联性，为阐明气候变暖情景下病毒对土壤碳氮循环的调控机制奠定基础。

病毒是土壤微生物群落和元素循环重要的调节者和参与者。然而，土壤病毒如何响应气候变暖尚缺乏深入研究。我国青藏高原高寒草甸储存丰富的土壤有机碳，同时也受到气候变暖日益严重的影响。因而，亟须查明增温条件下高寒草甸土壤病毒的多样性和群落结构变化规律，以及这些变化对宿主微生物群落的影响。本项目中，我们依托中国科学院海北站长期连续增温和降水耦合野外试验平台，采集土壤表层及亚表层样品，通过宏基因组鸟枪法测序，获取土壤病毒基因组，分析病毒群落多样性、群落结构，查明其对增温和降水变化的响应，并结合16S rRNA和ITS扩增子测序分析病毒潜在宿主群落的变化特征。我们发现高寒草甸土壤中含有特异的病毒物种，并且表层和亚表层土壤病毒群落差异极大。统计检验表明，亚表层土壤病毒对增温处理比表层土壤更为敏感，增温增加了物种之间的竞争。同时，病毒多样性及群落变化与土壤CO2通量，氨态氮含量及植物初级生产力显著相关，这表明病毒可能直接或间接调控了表层和亚表层的土壤碳循环过程。土壤潜在宿主微生物也收到增温的显著影响。经过4年的变暖处理，土壤细菌微生物群落的功能特性发生了迁移，甲烷吸收和有氧呼吸增加。由于变暖对NEE没有显著影响，变暖扩大了微生物对土壤甲烷的吸收，并增加了高山草甸的整体碳汇。