title: Expression of denitrification genes in response to a waterlogging event in a Fluvisol and its relationship with large nitrous oxide pulses.
abstract: The contributions of large N2 O pulses following waterlogging to the annual cumulative N2 O productions were significant in a Fluvisol. To uncover the mechanisms underlying these large N2 O pulses, a Fluvisol sampled from an agricultural field in Japan was subjected to waterlogging during incubation. Larger N2 O emissions were observed in intact soil cores when compared to emissions from sieved soils, indicating the importance of soil properties. The most important factor controlling the magnitude of the N2 O pulses after waterlogging was the soil moisture prior to waterlogging. The major pathway for N2 O production was denitrification. Quantitative PCR and quantitative RT-PCR analyses showed that the denitrification genes (nirS, nirK, and nosZ) correlated with N2 O emissions at the mRNA level but not at the DNA level. The change in denitrification gene mRNA levels was more prominent in the 0- to 1-cm soil compared with the 1- to 3-cm soil. Water-soluble and hot-water-soluble carbon contents also showed the highest amount in the 0- to 1-cm soil. These indicate that there was a strong variation in soil microbial properties over very small changes in soil depth, and this variation is important in determining the magnitude of N2 O emissions.
authors.affiliation: Task Force for Innovation in Life, Resources and Environment Sciences, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Uchida
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Hiroko
authors.initials: H
authors.lastname: Akiyama
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Masahito
authors.initials: M
authors.lastname: Hayatsu
mesh_terms: D001419:Bacteria / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D058440:Denitrification / Q000235:genetics*; D007564:Japan; D009566:Nitrates / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D014867:Water
chemical_list: D009566:Nitrates; D012987:Soil; D014867:Water; D002244:Carbon; D009609:Nitrous Oxide
keywords: 15N labeling; denitrifiers; nitrite reductase; nitrous oxide reductase; wetting