【作者】 任改弟； 朱春梧； 张华勇； 朱建国； Tokida Takeshi； Hasegawa Toshihiro； 贾仲君；

【Author】 Ren Gaidi~1,Zhu Chunwu~(1,2),Zhang Huayong~1,Zhu Jianguo~1,Tokida Takeshi~2, Hasegawa Toshihiro~2,Jia Zhongjun~1 (1.State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China; 2.National Institute for Agro-Environmental Sciences,Tsukuba 3058604,Japan)

【机构】 中国科学院土壤与农业可持续发展国家重点实验室； 日本国立农业环境技术研究所；

【摘要】 全球气候变化主要包括大气CO₂浓度升高、温度升高、近地层臭氧浓度升高、降雨量发生变化等。其中大气CO₂浓度升高、温度升高是全球气候变化对农业生产和农业生态系统影响最为重要的两个生态因子,主要表现在影响农作物生长发育、影响土壤养分循环,进而影响农业生态系统的结构和功能。微生物是农业生态系统的重要组成部分,研究微生物群落对全球气候变化的响应有利于进一步揭示农业生态系统对气候变化的调控机制。植物内生菌是指定殖于植物组织内部并不对植物造成危害的微生物。植物叶表（Phylosphere）是植物地上部分与外界空气相互作用的界面,定殖于此界面的微生物称之为叶表微生物（Phylopherebacteria）。据估计,全球的叶表面积达10亿平方千米,其定殖的微生物数量达到10²⁶个细菌细胞(10⁶ cell.cm^-2),植物内生菌和植物叶表微生物能够控制植物病原菌侵染和蔓延、促进植物生长并且可以作为生防菌剂,在粮食安全方面发挥了重要作用。已有的证据清楚表明大气CO₂浓度将持续升高,并可能在2050年达到550 ppm左右,同时全球地表温度将持续增加,并可能在2050年增加1.5℃～2.0℃。然而,未来大气CO₂浓度升高和全球增温下,叶表微生物和叶内微生物的响应与适应机制未见报道。本研究依托日本国立农业环境技术研究所的CO₂和温度FACE平台,针对四种处理:（1）大气CO₂浓度升高处理（CO₂-FACE,CO₂浓度增加200 ppm）;（2）土壤增温处理（Temperature-FACE,温度增加2.0℃）;（3）CO₂浓度和温度升高处理（CT-FACE）;以及（4）Ambient对照处理,利用新一代454高通量测序技术深度分析了植物上部叶片和下部叶片（叶表和叶内）,以及土壤微生物群落结构的变化规律。结果表明,Enterobacteriaceae是水稻叶内和叶表的的优势微生物菌群,其相对丰度达到90%。CO₂-FACE、Temperature-FACE和CT-FACE使得Enterobacteriaceae丰度降低（Temperature-FACE和CT-FACE对上叶叶表微生物的影响除外）,使得低丰度微生物菌群数量增多,此规律在Low-In表现最为明显。例如,Temperature-FACE和CT-FACE分别使得Enterobacteriaceae的相对丰度从92%（Ambient）降低为36%和63%（p<0.05）,使得Xanthomonadaceae的相对丰度从0.005%（Ambient）增加至46%和20%（p<0.05）。土壤中的优势微生物菌群是Betaproteobacteria,Actinobacteria,Firmicutes,Alphaproteobacteria,Deltaproteobacteria,和Gammaproteobacteria,其相对丰度之和达到约70%。CO₂-FACE、Temperature-FACE和CT-FACE使得土壤中的优势微生物菌群丰度从5.1%～26.2%下降至4.1%～23.2%,使低丰度微生物菌群（Bacteroidetes,Chloroflexi,Acidobacteria,Planctomycetes,Gemmatimonadetes,and Cyanobacteria）丰度从0.4%～5.1%增加至0.6%～7%。上述结果表明,大气CO₂浓度升高和土壤增温改变了稻田生态系统叶内微生物群落、叶表微生物群落以及土壤微生物群落的结构,此变化与土壤养分循环（例如碳氮循环）、植物生理变化的关系有待进一步研究。更多还原

【Abstract】 Global climate change mainly includes elevated atmospheric CO₂ concentration,improved global mean surface temperature,increased surface ozone concentration and changed precipitation.Of these changes,elevated atmospheric CO₂ concentration and improved global mean surface temperature are the most important ecological factors influencing crop growth and soil nutrient cycling,resulting in changed structure and function of agro-ecosystem.Microorganisms are an import component of ago-ecosystem.Research on microbial community response to climate change can help to understand the agro-ecosystem regulation mechanism.Endophytic bacteria can be defined as those bacteria that colonize the internal tissue of the plant showing no external sign of infection or negative effect on their host.The surface of plant leaves（the phyllosphere） represents the interface between the above-ground parts of plants and the air.The microorganisms that live in this interface are called phylosphere bacteria. Conservative estimates indicate that the roughly one billion square kilometers of worldwide leaf surfaces host more than 10²⁶ bacteria(10⁶cell.cm^-2).Numerous reports have shown that endophytic and phylospheric microorganisms could control plant pathogens,promote plant growth,act as biocontrol agents, and thus played an important role in food safety.Previous studies have clearly shown that the global atmospheric CO₂ concentration will continue to rise and is expected to reach about 550 ppm in 2050.At the same time the global surface temperature will continue to rise,and possibly will be increased by 1.5℃～2.0℃in 2050.However,the response and adaption mechanisms of the phylospheric and endophytic bacteria under elevated atmospheric CO₂ concentration and soil temperature have not been reported.Based on FACE research platform of National Institute for Agro-Environmental Sciences in Japan,using 454 high-throughout pyrosequencing technique,we deeply investigated microbial community structure changes in rice upper and lower leaf（leaf inside and outside） and soil（0～5cm） under four treatments,which include（1） free air CO₂ enrichment（CO₂-FACE,+200 ppm）,（2）elevated soil temperature treatment（Temperature-FACE,+2.0℃）,（3） Elevated atmospheric CO₂ concentration and soil temperature treatment（CT-FACE）,and（4） Ambient treatment（control）.The results revealed that the dominant phylotypes in leaf inside and outside comprised primarily of Enterobacteriaceae,accounting for～90%of the total 16S rRNA sequence reads.CO₂-FACE,Temperature-FACE,and CT-FACE treatments led to a significant decrease in the dominant phylotypes（except for the bacteria living in upper leaf outside under Temperature-FACE and CT-FACE treatments）,and a sharp increase in phylotypes with low abundance especially in Low-In leaf.For instance,Temperature-FACE and CT-FACE treatments resulted in a remarkable decrease in relative abundance of Enterobacteriaceae from 92%（Ambient） to 36%and 63% respectively（p<0.05）,and an obvious increase in Xanthomonadaceae from 0.005%（Ambient） to 46%and 20%respectively（p<0.05）.The dominant phylotypes across all soil samples were Betaproteobacteria, Actinobacteria,Firmicutes,Alphaproteobacteria,Deltaproteobacteria,and Gammaproteobacteria, accounting for～70%of the bacterial sequences from each of the soils.The relative abundance of these dominant phylotypes decreased from 5.1%～26.2%to 4.1%～23.2%,while the abudance of phylotyepes with low abundance such as Bacteroidetes,Chloroflexi,Acidobacteria,Planctomycetes, Gemmatimonadetes,and Cyanobacteria increased from 0.4%～5.1%in ambient soil to 0.6%～7%under CO₂-FACE,Temperature-FACE,and CT-FACE treatments.These results suggest that CO₂-FACE, Temperature-FACE,and CT-FACE treatments altered the structure of microbial communities of typical habitats（leaf inside,leaf outside,and soil） in paddy ecosystem.The relationships among these microbial community changes,soil nutrient cycling（such as carbon and nitrogen cycling）,and plant physiology should be studied further.更多还原