Elevated CO2 shifts the functional structure and metabolic potentials of soil microbial communities in a C4 agroecosystem.

Jizhong Zhou,Joy D. Van Nostrand,Angela Kent,Liyou Wu,Ye Deng,Shengjing Shi,Jinbo Xiong,Zhili He

doi:10.1038/srep09316

Abstract

Atmospheric CO2 concentration is continuously increasing, and previous studies have shown that elevated CO2 (eCO2) significantly impacts C3 plants and their soil microbial communities. However, little is known about effects of eCO2 on the compositional and functional structure, and metabolic potential of soil microbial communities under C4 plants. Here we showed that a C4 maize agroecosystem exposed to eCO2 for eight years shifted the functional and phylogenetic structure of soil microbial communities at both soil depths (0–5 cm and 5–15 cm) using EcoPlate and functional gene array (GeoChip 3.0) analyses. The abundances of key genes involved in carbon (C), nitrogen (N) and phosphorus (P) cycling were significantly stimulated under eCO2 at both soil depths, although some differences in carbon utilization patterns were observed between the two soil depths. Consistently, CO2 was found to be the dominant factor explaining 11.9% of the structural variation of functional genes, while depth and the interaction of depth and CO2 explained 5.2% and 3.8%, respectively. This study implies that eCO2 has profound effects on the functional structure and metabolic potential/activity of soil microbial communities associated with C4 plants, possibly leading to changes in ecosystem functioning and feedbacks to global change in C4 agroecosystems.

Highlights

Elevated CO2 shifts the functional structure and metabolic potentials of soil microbial communities in a C4 agroecosystem
Our results demonstrated that elevated CO2 (eCO2) had significant effects on the functional structure and metabolic potential of soil microbial communities with similar trends in both soil depths, and that many key functional genes involved in C, N, and
We demonstrated that the functional structure and metabolic potential of microbial communities in a C4 maize agroecosystem were significantly altered under crops fumigated with eCO2 for eight years

Summary

Total nitrogen

Soil variables from each depth were analyzed separately and significances between treatments (aCO2 and eCO2) or two soil depths were tested by t-test at the P, 0.05 level. We observed significant differences in the phylogenetic structure due to eCO2 and depth (Table 3) Such a pattern was observed at the functional gene category level, including C, N, P and CH4 cycling genes (Table S1). These results revealed that the diversity, composition, structure and functional potential of soil microbial communities were predominantly affected by eCO2 in this maize agroecosystem. Genes from the other two CO2 fixation pathways, CODH and Pcc/Acc, had significantly increased abundances under eCO2 in the soil depth of 5–15 cm, but their signal intensities did not differ significantly between two CO2 levels in the soil depth of 0–5 cm (Figure S2). Signal intensities of genes involved in nitrification (amoA and hao), and dissimilatory N reduction to ammonium (napA and nrfA) were only enhanced under eCO2 in the soil depth of 5–15 cm (Figure 4B)

MRPPc d

Functional structure Phylogenetic structure

Discussion

Methods

Author contributions

Findings

Additional information