Relationships between denitrification gene expression, dissimilatory nitrate reduction to ammonium and nitrous oxide and dinitrogen production in montane grassland soils
Relationships between denitrification gene expression, dissimilatory nitrate reduction to ammonium and nitrous oxide and dinitrogen production in montane grassland soils
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DOI：
10.1016/j.soilbio.2015.03.030
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发表时间：
2015-08-01
影响因子：
9.7
通讯作者：
Dannenmann, Michael
中科院分区：
文献类型：
--
作者：
Chen, Zhe;Wang, Changhui;Dannenmann, Michael
欧洲山地草原土壤储存了大量的氮，气候变化可能会刺激气态一氧化二氮（N2 O）和二氮（N-2）的流失，从而导致氮的挥发。因此，一个彻底的，机械的理解，负责氮素损失和保留，如反硝化和异化硝酸盐还原为铵（DNRA）在这些土壤中的过程是迫切需要的。在这里，我们的目的是探讨硝化酶基因丰度和表达与N-2和N2 O生产之间的关系，以及DNRA与反硝化作用在典型的德国南部山地草原土壤硝酸盐消耗和N2 O生产中的重要性。在一个实验室培养实验中，葡萄糖和硝酸盐添加，我们结合了直接测量的N2 O和N-2生产与分子分析的参与亚硝酸盐，一氧化氮（NO）和N2 O还原和量化DNRA的生物群落。土壤来源于一个时空气候变化实验，在实验中，完整的植物-土壤生态系统暴露在高海拔地区的环境条件下三年，（“HE”对照处理）或预测的气候变化条件（暖，减少夏季降水和减少冬季积雪）在LE土壤中，cnorB基因的丰度（DNA）显著降低，而nosZ基因的丰度在HE和LE土壤之间没有差异。然而，cnorB基因丰度的降低意外地导致了潜在N2 O排放的略微增加而不是减少。这种效应可以解释的cnorB mRNA水平的增加，因此，在LE土壤中的NO还原剂的生理活性较高。与DNA水平相比，cnorB mRNA水平的动态遵循N2 O排放模式，而nosZ表达与N-2排放密切相关（R-2 = 0.83）。DNRA的潜在反硝化速率约为反硝化速率的1/3，DNRA不是N2 O的来源，DNRA与反硝化之间存在明显的竞争，从而有助于土壤氮素的保存。这项工作表明，nosZ基因表达的分子分析有很大的潜力，有助于解决神秘的问题，了解N-2从土壤中流失。(C)2015爱思唯尔有限公司版权所有。
The montane grassland soils of Europe store significant amounts of nitrogen (N), and climate change might drive their volatilization due to the stimulation of gaseous nitrous oxide (N2O) and dinitrogen (N-2) losses. Hence, a thorough, mechanistic understanding of the processes responsible for N loss and retention such as denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in these soils is urgently needed. Here we aimed to explore the relationships between denitrifier gene abundance and expression with N-2 and N2O production and the importance of DNRA versus denitrification in nitrate consumption and N2O production for typical montane grassland soils of Southern Germany. In a laboratory incubation experiment with glucose and nitrate addition, we combined direct measurements of N2O and N-2 production with a molecular analysis of the denitrifier communities involved in nitrite, nitric oxide (NO) and N2O reduction and with the quantification of DNRA. The soils originated from a space-for-time climate change experiment, where intact plant-soil mesocosms were exposed for three years either to ambient conditions at a high elevation site ("HE" control treatment) or to predicted climate change conditions (warming, reduced summer precipitation and reduced winter snow cover) by translocation to lower elevation ("LE" climate change treatment).The abundance (DNA) of cnorB genes was significantly reduced in LE soils, whereas the abundance of nosZ genes did not differ between the HE and LE soils. However, the decreased abundance of cnorB genes unexpectedly resulted in slightly increased rather than decreased potential N2O emissions. This effect could be explained by the increased levels of cnorB mRNA and, therefore, the higher physiological activity of the NO reducers in the LE soils. In contrast with the DNA levels, the dynamics of the cnorB mRNA levels followed N2O emission patterns, whereas the nosZ expression was strongly correlated with the N-2 emission (R-2 = 0.83). The potential rates of DNRA were approximately one-third of the rates of denitrification, and DNRA was not a source for N2O.We conclude that DNRA significantly competes with denitrification in these soils, thus contributing to N conservation. This work demonstrates that the molecular analysis of nosZ gene expression has great potential to contribute to solving the enigmatic problem of understanding N-2 loss from soil. (C) 2015 Elsevier Ltd. All rights reserved.