Emissions of nitrous oxide from the leaves of grasses

Bowatte, Saman; Newton, Paul C. D.; Theobald, P. W.; Brock, Shona C.; Hunt, Chris L.; Lieffering, Mark; Sevier, Scott; Gebbie, Steve; Luo, Dongwen

doi:10.1007/s11104-013-1879-6

Cited by 23 publications

(18 citation statements)

References 18 publications

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“…In earlier literature, two hypotheses of plant N 2 O emission were proposed. One hypothesis is that plants serve as a conduit of soil-sourced N 2 O [9], and the second hypothesis is that NO 2 − assimilation by plants is the source of plant N 2 O [10]. Since nitrite is toxic to plants, plant NO 2 − reduction probably occurs in the biochemical reaction sequence of "NO 2 -NO-N 2 O-N 2 ", which provide a possibility for plants to emit N 2 O [11].…”

Section: Introductionmentioning

confidence: 99%

Is Endophyte-Plant Co-Denitrification a Source of Nitrous Oxides Emission? —An Experimental Investigation with Soybean

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2018

Agronomy

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The biological pattern of plants' nitrous oxide (N 2 O) generation is not well understood because plant cells cannot form N 2 O from nitric oxide (NO) reduction. Hypothetically, we consider that plant-endophytic co-denitrification is potentially capable of making up for the functional loss of NO reduction in the plant cell and is thus the source of plant-derived N 2 O. In order to test the above hypothesis, field-cultured soybean seedlings and aseptic-cultured seedlings were used to establish plant holobionts with differentially established endophytes. The N 2 O fluxes, copies of the bacterial NO reductase encoding gene, and a diversity of endophytic denitrifying bacteria of these holobionts were observed by gas chromatography, real-time PCR, and 16s rDNA sequencing. The flux of N 2 O by the field seedlings was significantly higher than the fluxes of the aseptic seedlings and bulk soil. The N 2 O flux of the soybean seedlings was significantly correlated to the abundance of the bacterial NO reductase encoding gene. Eleven genera of denitrifying bacteria were observed in the soybean seedlings, and among them, two genera of aerobic denitrifying bacteria were specifically associated with colonizing plant samples. In this work we have also showed that plant N 2 O emission is affected by the abundance of total endophytic denitrifying bacteria. We conclude that plant sourced N 2 O is cooperatively generated by the plant-endophyte symbiotic system in which endophytic denitrifying bacteria help plants to emit N 2 O by taking over the NO-N 2 O reduction process.

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Section: Introductionmentioning

confidence: 99%

Is Endophyte-Plant Co-Denitrification a Source of Nitrous Oxides Emission? —An Experimental Investigation with Soybean

Sun

2018

Agronomy

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“…The established wisdom is that N 2 O is generated exclusively by soil-based microbes such as ammonia-oxidising bacteria (AOB). This soil biology is represented in models designed to simulate N 2 O emissions and the soil is a target for mitigation strategies such as the use of nitrification inhibitors.We have previously shown that pasture plants can emit N 2 O largely through acting as a conduit for emissions generated in the soil, which are themselves controlled to some degree by the plant (Bowatte et al, 2014). In this case the origin of the emission is still the soil microbes.…”

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confidence: 99%

“…We have previously shown that pasture plants can emit N 2 O largely through acting as a conduit for emissions generated in the soil, which are themselves controlled to some degree by the plant (Bowatte et al, 2014). In this case the origin of the emission is still the soil microbes.…”

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confidence: 99%

“…The cores were installed in a chamber system designed to allow sampling of above-and belowground environments separately (Bowatte et al, 2014). N 2 O emissions were measured from untreated (control) plants and from plants where NH 3 was added to the aboveground chamber and leaves were either untreated or sterilised by wiping twice with paper towels soaked in 1% hypoclorite (Sturz et al, 1997) and then with sterile water.…”

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confidence: 99%

“…Control plants did emit N 2 O suggesting there was either sufficient NH 3 available for bacterially generated emissions and/or other plant-based mechanisms were involved (Bowatte et al, 2014).…”

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Bacteria on leaves: a previously unrecognised source of N2O in grazed pastures

et al. 2014

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Nitrous oxide (N 2 O) emissions from grazed pastures are a product of microbial transformations of nitrogen and the prevailing view is that these only occur in the soil. Here we show this is not the case. We have found ammonia-oxidising bacteria (AOB) are present on plant leaves where they produce N 2 O just as in soil. AOB (Nitrosospira sp. predominantly) on the pasture grass Lolium perenne converted 0.02-0.42% (mean 0.12%) of the oxidised ammonia to N 2 O. As we have found AOB to be ubiquitous on grasses sampled from urine patches, we propose a 'plant' source of N 2 O may be a feature of grazed grassland. The ISME Journal (2015) 9, 265-267; doi:10.1038/ismej.2014 published online 11 July 2014 In terms of climate forcing, nitrous oxide (N 2 O) is the third most important greenhouse gas (Blunden and Arndt, 2013). Agriculture is the largest source of anthropogenic N 2 O (Reay et al., 2012) with about 20% of agricultural emissions coming from grassland grazed by animals (Oenema et al., 2005).Grazed grassland is a major source of N 2 O because grazers harvest nitrogen (N) from plants across a wide area but recycle it back onto the pasture, largely as urine, in patches of very high N concentration. The N in urine patches is often in excess of what can be used by plants resulting in losses through leaching as nitrate, as N 2 O and through volatilisation as ammonia (NH 3 ) creating a high NH 3 environment in the soil and plant canopy; an important point that we will return to later. The established wisdom is that N 2 O is generated exclusively by soil-based microbes such as ammonia-oxidising bacteria (AOB). This soil biology is represented in models designed to simulate N 2 O emissions and the soil is a target for mitigation strategies such as the use of nitrification inhibitors.We have previously shown that pasture plants can emit N 2 O largely through acting as a conduit for emissions generated in the soil, which are themselves controlled to some degree by the plant (Bowatte et al., 2014). In this case the origin of the emission is still the soil microbes. However, AOB have been found on the leaves of plants, for example, Norway spruce (Papen et al., 2002; Teuber et al., 2007) and weeds in rice paddies (Bowatte et al., 2006), prompting us to ask whether AOB might be present on the leaves of pasture species and contribute to N 2 O emissions as they do in soil.We looked for AOB on plants in situations where NH 3 concentrations were likely to be high, choosing plants from urine patches in grazed pastures and plants from pastures surrounding a urea fertiliser manufacturing plant. DNA was extracted from the leaves (including both the surface and apoplast) and the presence of AOB tested using PCR. AOB were present in all the species we examined-the grasses Lolium perenne, Dactylis glomerata, Anthoxanthum odoratum, Poa pratensis, Bromus wildenowii and legumes Trifolium repens and T. subterraneum.To measure whether leaf AOB produce N 2 O, we used intact plants of ryegrass (L. perenne) lifted as cores from a paddock tha...

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Gaseous emissions and soil fertility of homegardens in the Nuba Mountains, Sudan

Goenster

Wiehle

Předotová

et al. 2015

J. Plant Nutr. Soil Sci.

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Intensification of homegardens in the Nuba Mountains may lead to increases in C and nutrient losses from these small-scale land-use systems and potentially threaten their sustainability. This study, therefore, aimed at determining gaseous C and N fluxes from homegarden soils of different soil moisture, temperature, and C and N status. Emissions of CO 2 , NH 3 , and N 2 O from soils of two traditional and two intensified homegardens and an uncultivated control were recorded biweekly during the rainy season in 2010. Flux rates were determined with a portable dynamic closed chamber system consisting of a photo-acoustic multi-gas field monitor connected to a PTFE coated chamber. Topsoil moisture and temperature were recorded simultaneously to the gas measurements. Across all homegardens emissions averaged 4,527 kg CO 2 -C ha -1 , 22 kg NH 3 -N ha -1 , and 11 kg N 2 O-N ha -1 for the observation period from June to December. Flux rates were largely positively correlated with soil moisture and predominantly negatively with soil temperature. Significant positive, but weak (r s < 0.34) correlations between increasing management intensity and emissions were noted for CO 2 -C. Similarly, morning emissions of NH 3 and increasing management intensity were weakly correlated (r s = 0.17). The relatively high gaseous C and N losses in the studied homegardens call for effective management practices to secure the soil organic C status of these traditional land-use systems.

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Emissions of nitrous oxide from the leaves of grasses

Cited by 23 publications

References 18 publications

Is Endophyte-Plant Co-Denitrification a Source of Nitrous Oxides Emission? —An Experimental Investigation with Soybean

Is Endophyte-Plant Co-Denitrification a Source of Nitrous Oxides Emission? —An Experimental Investigation with Soybean

Bacteria on leaves: a previously unrecognised source of N2O in grazed pastures

Gaseous emissions and soil fertility of homegardens in the Nuba Mountains, Sudan

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