/AnMtgsAbsts2009.53101 Metagenomic Insights of the Feedback Responses of Soil Microbial Communities to Elevated CO2.

Wednesday, November 4, 2009: 2:35 PM
Convention Center, Room 407, Fourth Floor

Jizhong Zhou1, Zhili He1, Meiying Xu1, Ye Deng1, Liyou Wu1, Sanghoon Kang1, Peter Reich2 and Sarah Hobbie3, (1)Institute for Environmental Genomics, Univ. of Oklahoma, Norman, OK
(2)Forest Resources, Univ. of Minnesota, St. Paul, MN
(3)Univ. of Minnesota, St. Paul, MN
Abstract:
Understanding the responses and mechanisms of biological communities to elevated atmosphere carbon dioxide (eCO2) is a central issue in ecology and for society.  Although the fertilization effects of eCO2 on aboveground plants are well documented, its influences on belowground microbial communities are poorly understood. The responses of belowground microbial communities to eCO2 will critically influence whether and how much the fertilization effects will lead to C loss or sequestration in terrestrial ecosystems. We used high throughput metagenomics technologies, such as GeoChip and pyrosequencing, to address the following questions: (i) Does elevated [CO2] affect the composition of soil microbial communities? (ii) Does elevated [CO2] affect soil microbial functional genes likely to influence carbon and nitrogen cycles under elevated CO2?   Our results show that eCO2 significantly altered the genetic and functional structure of the belowground microbial community in a grassland ecosystem in eastern Minnesota after 10 years of field exposure to eCO2. Soil community responses are consistent with and help explain ecosystem responses involving soil carbon and nitrogen content and plant productivity. Specifically, while the functional genes involved in degrading labile carbon are significantly increased under eCO2, the genes for decomposing recalcitrant carbon remain unchanged. The genes involved in fixing carbon and nitrogen and releasing phosphorus are also significantly increased. The results suggest that elevated [CO2] has significant impacts on relative abundance, composition and potential functions of soil microbial communities, and they could have important implications for the feedback responses of ecosystems to atmospheric CO2 and hence to the global climate change modeling needed for reliable prediction of future atmospheric CO2.