Abstract：
Methanogenic and methanotrophic microbes together determine the net methane flux from rice fields. Despite much research on them as separate communities, there has been little study of combined community patterns, and how these vary between the rhizoplane (root surface), rhizosphere (soil surrounding the root) and bulk soil around rice plants, especially at larger spatial scale. We collected samples from 32 geographically scattered rice fields in east central China, amplicon targeting the mcrA gene for methanogenesis and pmoA gene for methanotrophy by using high-throughput sequencing. Distinct communities of both methanogens and methanotrophs occurred in each of the three compartments, and predominantly positive links were found between methanogens and methanotrophs in all compartments indicating cross-feeding or consortia relationships. Methanogens were acting as the network hub in the bulk soil, and methanotrophs in rhizoplane. Network complexity and stability was greater in the rhizosphere than rhizoplane and bulk soil, with no network hubs detected, suggesting the strongest effect of homeostatic influence by plant occurred in the rhizosphere. The proportion of determinism (homogeneous selection) and distance-decay relation (DDR) in rhizoplane was consistently lower than that in the rhizosphere for both communities, indicating weaker phylogenetic clustering in rice root surface. Our results have provided a better understanding of CH4 oxidation and emission in rice paddy fields and future agriculture management could take into consideration of the subtle variation among different soil compartments and interactions within methanogenic and methanotrophic communities.
摘要：
产甲烷和甲烷营养微生物共同决定了稻田的净甲烷通量。尽管对他们作为独立社区进行了大量研究，很少有关于联合社区模式的研究，以及这些在根际平面(根表面)之间是如何变化的，根际（根周围的土壤）和水稻植物周围的块状土壤，尤其是在更大的空间尺度上。我们从中国中东部32个地理上分散的稻田中收集了样本，通过使用高通量测序靶向用于甲烷生成的mcrA基因和用于甲烷营养的pmoA基因的扩增子。产甲烷菌和甲烷营养菌的不同群落出现在三个隔室中的每个隔室中，在所有隔室中，产甲烷菌和甲烷营养菌之间都发现了主要的正联系，这表明了交叉进食或聚生体关系。产甲烷菌是散装土壤中的网络枢纽，和根际平面中的甲烷营养生物。根际的网络复杂性和稳定性大于根际平面和块状土壤，没有检测到网络集线器，表明植物对稳态影响的最强影响发生在根际。对于两个群落，根际平面中的决定论（均匀选择）和距离衰减关系（DDR）的比例始终低于根际，表明水稻根表面系统发育聚类较弱。我们的结果为稻田中的CH4氧化和排放提供了更好的理解，未来的农业管理可以考虑不同土壤隔室之间的细微变化以及产甲烷和甲烷营养群落之间的相互作用。
