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Responses of Methanogenic and Methanotrophic Communities to Elevated Atmospheric CO 2 and Temperature in a Paddy Field

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ABSTRACT

Although climate change is predicted to affect methane (CH4) emissions in paddy soil, the dynamics of methanogens and methanotrophs in paddy fields under climate change have not yet been fully investigated. To address this issue, a multifactor climate change experiment was conducted in a Chinese paddy field using the following experimental treatments: (1) enrichment of atmospheric CO2 concentrations (500 ppm, CE), (2) canopy air warming (2°C above the ambient, WA), (3) combined CO2 enrichment and warming (CW), and (4) ambient conditions (CK). We analyzed the abundance of methanogens and methanotrophs, community structures, CH4 production and oxidation potentials, in situ CH4 emissions using real-time PCR, T-RFLP, and clone library techniques, as well as biochemical assays. Compared to the control under CE and CW treatments, CH4 production potential, methanogenic gene abundance and soil microbial biomass carbon significantly increased; the methanogenic community, however, remained stable. The canopy air warming treatment only had an effect on CH4 oxidation potential at the ripening stage. Phylogenic analysis indicated that methanogens in the rhizosphere were dominated by Methanosarcina, Methanocellales, Methanobacteriales, and Methanomicrobiales, while methanotrophic sequences were classified as Methylococcus, Methylocaldum, Methylomonas, Methylosarcina (Type I) and Methylocystis (Type II). However, the relative abundance of Methylococcus (Type I) decreased under CE and CW treatments and the relative abundance of Methylocystis (Type II) increased. The in situ CH4 fluxes indicated similar seasonal patterns between treatments; both CE and CW increased CH4 emissions. In conclusion results suggest that methanogens and methanotrophs respond differently to elevated atmospheric CO2 concentrations and warming, thus adding insights into the effects of simulated global climate change on CH4 emissions in paddy fields.

No MeSH data available.


Principal component analysis (PCA) of T-RFLP patterns of methanogens (A) and methanotrophs (B) from the studied soils. Tillering stage (white); Heading stage (light gray); Ripening stage (black). The symbols are as follows: ambient CO2 and ambient temperature (CK), squares; atmosphere CO2 enrichment (CE), triangles; atmosphere CO2 enrichment and warming canopy air (CW), circles; warming canopy air (WA), diamonds. The error bars indicate the standard error of the means.
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Figure 2: Principal component analysis (PCA) of T-RFLP patterns of methanogens (A) and methanotrophs (B) from the studied soils. Tillering stage (white); Heading stage (light gray); Ripening stage (black). The symbols are as follows: ambient CO2 and ambient temperature (CK), squares; atmosphere CO2 enrichment (CE), triangles; atmosphere CO2 enrichment and warming canopy air (CW), circles; warming canopy air (WA), diamonds. The error bars indicate the standard error of the means.

Mentions: The methanogenic and methanotrophic community structures were analyzed using T-RFLP fingerprints. PCA of the T-RFLP profiles at the three growth stages yielded summaries of data, as 51.4% for mcrA genes and 61.8% for pmoA genes of the total variability was explained by PC1 and PC2 (Figure 2). No clear differences in the methanogenic community structure between the treatments and across the growth stages were highlighted by PCA analysis. Figure 2B shows that the methanotrophic community structure under CE, CW, and WA was distinctively separated from the control at each stage.


Responses of Methanogenic and Methanotrophic Communities to Elevated Atmospheric CO 2 and Temperature in a Paddy Field
Principal component analysis (PCA) of T-RFLP patterns of methanogens (A) and methanotrophs (B) from the studied soils. Tillering stage (white); Heading stage (light gray); Ripening stage (black). The symbols are as follows: ambient CO2 and ambient temperature (CK), squares; atmosphere CO2 enrichment (CE), triangles; atmosphere CO2 enrichment and warming canopy air (CW), circles; warming canopy air (WA), diamonds. The error bars indicate the standard error of the means.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121223&req=5

Figure 2: Principal component analysis (PCA) of T-RFLP patterns of methanogens (A) and methanotrophs (B) from the studied soils. Tillering stage (white); Heading stage (light gray); Ripening stage (black). The symbols are as follows: ambient CO2 and ambient temperature (CK), squares; atmosphere CO2 enrichment (CE), triangles; atmosphere CO2 enrichment and warming canopy air (CW), circles; warming canopy air (WA), diamonds. The error bars indicate the standard error of the means.
Mentions: The methanogenic and methanotrophic community structures were analyzed using T-RFLP fingerprints. PCA of the T-RFLP profiles at the three growth stages yielded summaries of data, as 51.4% for mcrA genes and 61.8% for pmoA genes of the total variability was explained by PC1 and PC2 (Figure 2). No clear differences in the methanogenic community structure between the treatments and across the growth stages were highlighted by PCA analysis. Figure 2B shows that the methanotrophic community structure under CE, CW, and WA was distinctively separated from the control at each stage.

View Article: PubMed Central - PubMed

ABSTRACT

Although climate change is predicted to affect methane (CH4) emissions in paddy soil, the dynamics of methanogens and methanotrophs in paddy fields under climate change have not yet been fully investigated. To address this issue, a multifactor climate change experiment was conducted in a Chinese paddy field using the following experimental treatments: (1) enrichment of atmospheric CO2 concentrations (500 ppm, CE), (2) canopy air warming (2°C above the ambient, WA), (3) combined CO2 enrichment and warming (CW), and (4) ambient conditions (CK). We analyzed the abundance of methanogens and methanotrophs, community structures, CH4 production and oxidation potentials, in situ CH4 emissions using real-time PCR, T-RFLP, and clone library techniques, as well as biochemical assays. Compared to the control under CE and CW treatments, CH4 production potential, methanogenic gene abundance and soil microbial biomass carbon significantly increased; the methanogenic community, however, remained stable. The canopy air warming treatment only had an effect on CH4 oxidation potential at the ripening stage. Phylogenic analysis indicated that methanogens in the rhizosphere were dominated by Methanosarcina, Methanocellales, Methanobacteriales, and Methanomicrobiales, while methanotrophic sequences were classified as Methylococcus, Methylocaldum, Methylomonas, Methylosarcina (Type I) and Methylocystis (Type II). However, the relative abundance of Methylococcus (Type I) decreased under CE and CW treatments and the relative abundance of Methylocystis (Type II) increased. The in situ CH4 fluxes indicated similar seasonal patterns between treatments; both CE and CW increased CH4 emissions. In conclusion results suggest that methanogens and methanotrophs respond differently to elevated atmospheric CO2 concentrations and warming, thus adding insights into the effects of simulated global climate change on CH4 emissions in paddy fields.

No MeSH data available.