Material cycling in plant-associated bacteria by metagenome analysis

研究了低施氮量（LN）和标准施氮量（SN）水稻细菌群落。宏基因组分析表明，LN和SN根微生物组之间的细菌群落发生了变化。LN根菌群中甲烷氧化功能基因丰度显著增加。CCaMK认为植物与微生物存在共生关系。我们检测了一个OsCCaMK突变体（NE1115）的影响。NE1115在LN场中的CH4通量显著高于WT，而在SN场中没有差异。qPCR和13C/15N同位素测定结果表明，在LN田间，WT水稻的根部同时激活了CH4氧化和N2固定，这两个过程可能都受到OsCCaMK的控制。元蛋白质组学和CARD-FISH分析表明，这两个过程都是由居住在水稻根维管束和表皮细胞中的II型甲烷化菌介导的。

We investigated bacterial communities in paddy rice with low (LN), standard (SN) levels of N fertilizer application. Metagenome analysis suggested shifts of bacterial communities between LN and SN root microbiomes. The abundances of functional genes for methane oxidation were significantly increased in LN root microbiome. Plants have mutualistic symbiotic relationships with microorganisms by CCaMK. We examined the effect of an OsCCaMK mutant (NE1115). The CH4 flux of NE1115 in the LN field was significantly higher than that of WT, although no difference was observed in the SN field. qPCR and 13C/15N isotopic determinations suggested that CH4 oxidation and N2 fixation were simultaneously activated in the root of WT rice in the LN field, and both processes are likely controlled by OsCCaMK. Metaproteome and CARD-FISH analyses demonstrated that both processes are mediated by type II methanotrophs inhabiting the vascular bundles and epidermal cells of the rice roots.