Warming Alters Expressions of Microbial Functional Genes Important to Ecosystem Functioning.

Kai Xue,Jianping Xie,Aifen Zhou,Dejun Li,Zhili He,Yiqi Luo,Joy D Van Nostrand,Liyou Wu,Feifei Liu,Jizhong Zhou,Ye Deng

doi:10.3389/fmicb.2016.00668

Abstract

Soil microbial communities play critical roles in ecosystem functioning and are likely altered by climate warming. However, so far, little is known about effects of warming on microbial functional gene expressions. Here, we applied functional gene array (GeoChip 3.0) to analyze cDNA reversely transcribed from total RNA to assess expressed functional genes in active soil microbial communities after nine years of experimental warming in a tallgrass prairie. Our results showed that warming significantly altered the community wide gene expressions. Specifically, expressed genes for degrading more recalcitrant carbon were stimulated by warming, likely linked to the plant community shift toward more C4 species under warming and to decrease the long-term soil carbon stability. In addition, warming changed expressed genes in labile C degradation and N cycling in different directions (increase and decrease), possibly reflecting the dynamics of labile C and available N pools during sampling. However, the average abundances of expressed genes in phosphorus and sulfur cycling were all increased by warming, implying a stable trend of accelerated P and S processes which might be a mechanism to sustain higher plant growth. Furthermore, the expressed gene composition was closely related to both dynamic (e.g., soil moisture) and stable environmental attributes (e.g., C4 leaf C or N content), indicating that RNA analyses could also capture certain stable trends in the long-term treatment. Overall, this study revealed the importance of elucidating functional gene expressions of soil microbial community in enhancing our understanding of ecosystem responses to warming.

Highlights

Global climate change resulting from anthropogenic activities (Novotny et al, 2007) has become one of the greatest scientific and political concerns (IPCC, 2007)
The GeoChip analysis was performed with cDNA that was reversely transcribed from total RNA to investigate functional gene expressions
An understanding of soil microbial community is critical to our ability to assess terrestrial ecosystem responses and feedbacks (Bardgett et al, 2008)

Summary

Introduction

Global climate change resulting from anthropogenic activities (Novotny et al, 2007) has become one of the greatest scientific and political concerns (IPCC, 2007). The yearly average global CO2 concentration is predicted to surpass 400 ppm in only a few years (Monastersky, 2013). The emissions of CO2 and Warming Influences Microbial Gene Expressions other greenhouse gasses had driven the Earth’s average temperature to increase by 0.74◦C in the 20th century, which may continue to increase by 1.1–6.4◦C at the end of this century (IPCC, 2007). Within the global climate change context, the soil microbial community is likely to be influenced by the atmospheric warming. The temperature increase itself affects almost all chemical and biological processes (Shaver et al, 2000) and may alter the soil microbial community directly. Warming may influence the soil microbial community via its indirect effects on plant communities (Cheng et al, 2010). The above-ground plant community shift under warming may lead to changes in plant-derived soil carbon (C) input that is important substrate for soil microbial community, and may alter soil microbial community

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Results

Conclusion