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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.


Relative abundance of T-RFs for mcrA (A) and pmoA(B) genes as determined by T-RFLP analysis in the studied soils. CK, ambient CO2 and ambient temperature; CE, atmosphere CO2 enrichment; CW, atmosphere CO2 enrichment and warming canopy air; WA, warming canopy air. Only major T-RFs (reductive abundance >1%) are shown. The error bars indicate the standard error of the means (n = 3).
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Figure 3: Relative abundance of T-RFs for mcrA (A) and pmoA(B) genes as determined by T-RFLP analysis in the studied soils. CK, ambient CO2 and ambient temperature; CE, atmosphere CO2 enrichment; CW, atmosphere CO2 enrichment and warming canopy air; WA, warming canopy air. Only major T-RFs (reductive abundance >1%) are shown. The error bars indicate the standard error of the means (n = 3).

Mentions: A total of 12 and 8 T-RFs were obtained from the overall samples for mcrA and pmoA genes, respectively. T-RFLP fingerprinting of mcrA genes revealed that the 268bp, 289bp, 306bp, and 460bp TRFs were dominant in all treatments, while T-RFs of 76bp, 245bp, 437bp, and 510bp were dominant in the methanotrophic pmoA T-RFLP profiles (Figure 3). The main T-RFs in the T-RFLP profiles were identified with in silico restriction of clone sequences. T-RFs related to Methanosarcina were the most predominant (35–45%) across all treatments while T-RFs related to Methanocellales and Methanobacteriales ranged from 19–29% and 13–28%, respectively. The effect of simulated climate change scenarios on the relative abundance of mcrA TRFs was insignificant. However, the relative abundance of the 76bp TRF, related to Methylococcus, decreased under CE and CW treatments at the later growth stages, while that of the 437bp TRF related to Methylocystis increased.


Responses of Methanogenic and Methanotrophic Communities to Elevated Atmospheric CO 2 and Temperature in a Paddy Field
Relative abundance of T-RFs for mcrA (A) and pmoA(B) genes as determined by T-RFLP analysis in the studied soils. CK, ambient CO2 and ambient temperature; CE, atmosphere CO2 enrichment; CW, atmosphere CO2 enrichment and warming canopy air; WA, warming canopy air. Only major T-RFs (reductive abundance >1%) are shown. The error bars indicate the standard error of the means (n = 3).
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Relative abundance of T-RFs for mcrA (A) and pmoA(B) genes as determined by T-RFLP analysis in the studied soils. CK, ambient CO2 and ambient temperature; CE, atmosphere CO2 enrichment; CW, atmosphere CO2 enrichment and warming canopy air; WA, warming canopy air. Only major T-RFs (reductive abundance >1%) are shown. The error bars indicate the standard error of the means (n = 3).
Mentions: A total of 12 and 8 T-RFs were obtained from the overall samples for mcrA and pmoA genes, respectively. T-RFLP fingerprinting of mcrA genes revealed that the 268bp, 289bp, 306bp, and 460bp TRFs were dominant in all treatments, while T-RFs of 76bp, 245bp, 437bp, and 510bp were dominant in the methanotrophic pmoA T-RFLP profiles (Figure 3). The main T-RFs in the T-RFLP profiles were identified with in silico restriction of clone sequences. T-RFs related to Methanosarcina were the most predominant (35–45%) across all treatments while T-RFs related to Methanocellales and Methanobacteriales ranged from 19–29% and 13–28%, respectively. The effect of simulated climate change scenarios on the relative abundance of mcrA TRFs was insignificant. However, the relative abundance of the 76bp TRF, related to Methylococcus, decreased under CE and CW treatments at the later growth stages, while that of the 437bp TRF related to Methylocystis increased.

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.