Limits...
The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

Domeignoz-Horta LA, Spor A, Bru D, Breuil MC, Bizouard F, Léonard J, Philippot L - Front Microbiol (2015)

Bottom Line: The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing.Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio.Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1347 Agroécologie Dijon, France.

ABSTRACT
Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

No MeSH data available.


Variation partitioning of denitrification activities. (A) Variance in denitrification activities was partitionned into nosZ diversity (D), soil physicochemical properties (S), denitrifiers abundance (A) and by combinations of predictors. Geometric areas are proportional to the respective percentages of explained variation. The edges of the triangle depict the variation explained by each factor alone. Percentages of variation explained by interactions of two or all factors are indicated on the sides and in the middle of the triangles, respectively. (B) Variance partitioning of potential N2O emissions. (C) Variance partitioning of potential denitrification activity (PDA). (D) Variance partitioning of final denitrification product [r(N2O/r(N2O+N2)]. The variables used for each variation partitioning are indicated in the Table S2.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4585238&req=5

Figure 3: Variation partitioning of denitrification activities. (A) Variance in denitrification activities was partitionned into nosZ diversity (D), soil physicochemical properties (S), denitrifiers abundance (A) and by combinations of predictors. Geometric areas are proportional to the respective percentages of explained variation. The edges of the triangle depict the variation explained by each factor alone. Percentages of variation explained by interactions of two or all factors are indicated on the sides and in the middle of the triangles, respectively. (B) Variance partitioning of potential N2O emissions. (C) Variance partitioning of potential denitrification activity (PDA). (D) Variance partitioning of final denitrification product [r(N2O/r(N2O+N2)]. The variables used for each variation partitioning are indicated in the Table S2.

Mentions: We used variance partitioning technique to quantify the relative contribution of the different groups of variables to the variation in N2 production by denitrification across samples (Figures 3A–D). The physical and chemical characteristics of the soil, the abundance of N2O producers and reducers, and the diversity of N2O reducers were used as explanatory variables. After model selection using multiple linear regressions (Table S2), the physical and chemical properties of the soil were found to be the variables that contributed most to the potential N2O production and PDA, explaining up to 29 and 45% of the variance, respectively (Figures 3B,C). In contrast, the [rN2O/r(N2O+N2)] was mostly explained by the diversity of the N2O-reducers (26%). Interactions between physical and chemical properties of the soil and the diversity of the N2O-reducing communities accounted for 26 and 17% of potential N2O production and [rN2O/r(N2O+N2)], respectively (Figures 3B,D). The importance of nosZII diversity for the end product ratio of denitrification was also suggested by the strong negative correlation between the (rN2O/r(N2O+N2)) and the nosZII diversity (r = -0.70, P < 0.0001) (Figure S4). The abundance of the communities studied made only a marginal contribution, explaining 2% of the variance in [rN2O/r(N2O+N2)].


The diversity of the N2O reducers matters for the N2O:N2 denitrification end-product ratio across an annual and a perennial cropping system.

Domeignoz-Horta LA, Spor A, Bru D, Breuil MC, Bizouard F, Léonard J, Philippot L - Front Microbiol (2015)

Variation partitioning of denitrification activities. (A) Variance in denitrification activities was partitionned into nosZ diversity (D), soil physicochemical properties (S), denitrifiers abundance (A) and by combinations of predictors. Geometric areas are proportional to the respective percentages of explained variation. The edges of the triangle depict the variation explained by each factor alone. Percentages of variation explained by interactions of two or all factors are indicated on the sides and in the middle of the triangles, respectively. (B) Variance partitioning of potential N2O emissions. (C) Variance partitioning of potential denitrification activity (PDA). (D) Variance partitioning of final denitrification product [r(N2O/r(N2O+N2)]. The variables used for each variation partitioning are indicated in the Table S2.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585238&req=5

Figure 3: Variation partitioning of denitrification activities. (A) Variance in denitrification activities was partitionned into nosZ diversity (D), soil physicochemical properties (S), denitrifiers abundance (A) and by combinations of predictors. Geometric areas are proportional to the respective percentages of explained variation. The edges of the triangle depict the variation explained by each factor alone. Percentages of variation explained by interactions of two or all factors are indicated on the sides and in the middle of the triangles, respectively. (B) Variance partitioning of potential N2O emissions. (C) Variance partitioning of potential denitrification activity (PDA). (D) Variance partitioning of final denitrification product [r(N2O/r(N2O+N2)]. The variables used for each variation partitioning are indicated in the Table S2.
Mentions: We used variance partitioning technique to quantify the relative contribution of the different groups of variables to the variation in N2 production by denitrification across samples (Figures 3A–D). The physical and chemical characteristics of the soil, the abundance of N2O producers and reducers, and the diversity of N2O reducers were used as explanatory variables. After model selection using multiple linear regressions (Table S2), the physical and chemical properties of the soil were found to be the variables that contributed most to the potential N2O production and PDA, explaining up to 29 and 45% of the variance, respectively (Figures 3B,C). In contrast, the [rN2O/r(N2O+N2)] was mostly explained by the diversity of the N2O-reducers (26%). Interactions between physical and chemical properties of the soil and the diversity of the N2O-reducing communities accounted for 26 and 17% of potential N2O production and [rN2O/r(N2O+N2)], respectively (Figures 3B,D). The importance of nosZII diversity for the end product ratio of denitrification was also suggested by the strong negative correlation between the (rN2O/r(N2O+N2)) and the nosZII diversity (r = -0.70, P < 0.0001) (Figure S4). The abundance of the communities studied made only a marginal contribution, explaining 2% of the variance in [rN2O/r(N2O+N2)].

Bottom Line: The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing.Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio.Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

View Article: PubMed Central - PubMed

Affiliation: INRA, UMR 1347 Agroécologie Dijon, France.

ABSTRACT
Agriculture is the main source of terrestrial emissions of N2O, a potent greenhouse gas and the main cause of ozone layer depletion. The reduction of N2O into N2 by microorganisms carrying the nitrous oxide reductase gene (nosZ) is the only biological process known to eliminate this greenhouse gas. Recent studies showed that a previously unknown clade of N2O-reducers was related to the capacity of the soil to act as an N2O sink, opening the way for new strategies to mitigate emissions. Here, we investigated whether the agricultural practices could differently influence the two N2O reducer clades with consequences for denitrification end-products. The abundance of N2O-reducers and producers was quantified by real-time PCR, and the diversity of both nosZ clades was determined by 454 pyrosequencing. Potential N2O production and potential denitrification activity were used to calculate the denitrification gaseous end-product ratio. Overall, the results showed limited differences between management practices but there were significant differences between cropping systems in both the abundance and structure of the nosZII community, as well as in the [rN2O/r(N2O+N2)] ratio. More limited differences were observed in the nosZI community, suggesting that the newly identified nosZII clade is more sensitive than nosZI to environmental changes. Potential denitrification activity and potential N2O production were explained mainly by the soil properties while the diversity of the nosZII clade on its own explained 26% of the denitrification end-product ratio, which highlights the importance of understanding the ecology of this newly identified clade of N2O reducers for mitigation strategies.

No MeSH data available.