Ikeda Seishi, Sasaki Kazuhiro, Okubo Takashi, Yamashita Akifumu, Terasawa Kimihiro, Bao Zhihua, Liu Dongyan, Watanabe Takeshi, Murase Jun, Asakawa Susumu, Eda Shima, Mitsui Hisayuki, Sato Tadashi, Minamisawa Kiwamu
Graduate School of Life Sciences, Tohoku University.
Microbes Environ. 2014;29(1):50-9. doi: 10.1264/jsme2.me13110. Epub 2014 Jan 24.
Reduced fertilizer usage is one of the objectives of field management in the pursuit of sustainable agriculture. Here, we report on shifts of bacterial communities in paddy rice ecosystems with low (LN), standard (SN), and high (HN) levels of N fertilizer application (0, 30, and 300 kg N ha(-1), respectively). The LN field had received no N fertilizer for 5 years prior to the experiment. The LN and HN plants showed a 50% decrease and a 60% increase in biomass compared with the SN plant biomass, respectively. Analyses of 16S rRNA genes suggested shifts of bacterial communities between the LN and SN root microbiomes, which were statistically confirmed by metagenome analyses. The relative abundances of Burkholderia, Bradyrhizobium and Methylosinus were significantly increased in root microbiome of the LN field relative to the SN field. Conversely, the abundance of methanogenic archaea was reduced in the LN field relative to the SN field. The functional genes for methane oxidation (pmo and mmo) and plant association (acdS and iaaMH) were significantly abundant in the LN root microbiome. Quantitative PCR of pmoA/mcrA genes and a (13)C methane experiment provided evidence of more active methane oxidation in the rice roots of the LN field. In addition, functional genes for the metabolism of N, S, Fe, and aromatic compounds were more abundant in the LN root microbiome. These results suggest that low-N-fertilizer management is an important factor in shaping the microbial community structure containing key microbes for plant associations and biogeochemical processes in paddy rice ecosystems.
减少化肥使用是追求可持续农业的田间管理目标之一。在此，我们报告了在低氮（LN）、标准氮（SN）和高氮（HN）水平（分别为0、30和300 kg N ha⁻¹）的水稻生态系统中细菌群落的变化。在实验前，LN田块已有5年未施氮肥。与SN植株生物量相比，LN和HN植株的生物量分别减少了50%和增加了60%。对16S rRNA基因的分析表明，LN和SN根际微生物群落之间存在变化，宏基因组分析在统计学上证实了这一点。相对于SN田块，LN田块根际微生物群落中伯克霍尔德氏菌属、慢生根瘤菌属和甲基弯曲菌属的相对丰度显著增加。相反，相对于SN田块，LN田块中甲烷产古菌的丰度降低。甲烷氧化功能基因（pmo和mmo）以及植物关联功能基因（acdS和iaaMH）在LN根际微生物群落中显著丰富。pmoA/mcrA基因的定量PCR和¹³C甲烷实验提供了LN田块水稻根中甲烷氧化更活跃的证据。此外，氮、硫、铁和芳香化合物代谢的功能基因在LN根际微生物群落中更为丰富。这些结果表明，低氮肥管理是塑造水稻生态系统中包含植物关联和生物地球化学过程关键微生物的微生物群落结构的一个重要因素。
