Conversion of upland to paddy field specifically alters the community structure of archaeal ammonia oxidizers in an acid soil

[摘要] The function of ammonia-oxidizing archaea (AOA) and bacteria (AOB) depends onthe major energy-generating compounds (i.e., ammonia and oxygen). Thediversification of AOA and AOB communities along ecological gradients ofsubstrate availability in a complex environment have been much debated butrarely tested. In this study, two ecosystems of maize and rice crops underdifferent fertilization regimes were selected to investigate the communitydiversification of soil AOA and AOB upon conversion of an upland field to apaddy field and long-term field fertilization in an acid soil. Real-timequantitative polymerase chain reaction of ammonia monooxygenase (amoA) genesdemonstrated that the abundance of AOA was significantly stimulated afterconversion of upland to paddy soils for more than 100 yr, whereas a slightdecline in AOB numbers was observed. Denaturing gradient gel electrophoresis fingerprints of amoA genesfurther revealed remarkable changes in the community compositions of AOAafter conversion of aerobic upland to flooded paddy field. Sequencinganalysis revealed that upland soil was dominated by AOA within the soil group1.1b lineage, whereas the marine group 1.1a-associated lineage predominatedin AOA communities in paddy soils. Irrespective of whether the soil wasupland or paddy soil, long-term field fertilization led to increasedabundance of amoA genes in AOA and AOB compared with controltreatments (no fertilization), whereas archaeal amoA gene abundancesoutnumbered their bacterial counterparts in all samples. Phylogeneticanalyses of amoA genes showed that Nitrosospira cluster-3-like AOB dominated bacterial ammonia oxidizers in both paddy and uplandsoils, regardless of fertilization treatment. The results of this studysuggest that the marine group 1.1a-associated AOA will be better adapted tothe flooded paddy field than AOA ecotypes of the soil group 1.1b lineage, andindicate that long-term flooding is the dominant selective force driving thecommunity diversification of AOA populations in the acid soil tested.

[学科分类] 地球化学与岩石