湘南红壤稻田AOA-amoA、narG、nosZ基因丰度及其环境影响因子

摘要

In order to explore the characteristics of the functional microbes involving in the N-circle and the general relationships among those microbes and the environmental factors in red paddy soils,the functional gene abundances of AOA-amoA,narG,nosZ and the environmental factors were investigated.Typical red paddy soils in Qiyang,Hunan province,where the double season rice had been popular for more than 30 years,were selected.Soils from 12 sites were sampled at three different stages,i.e.before soil preparation (S1),before transplanting of early rice (S2) and the mature stage of early rice (S3) in 2013.The abundances of AOA-amoA,narG,nosZ genes were measured by real-time quantitative PCR and probed by principal component analysis (PCA) and redundancy analysis (RDA).The relationships among the abundances of these genes and soil environmental factors were studied furthedy.Significant positive correlations were found among the abundances of AOA-amoA,narG and nosZ;the abundances of AOA-amoA,narG and nosZ genes decreased along with the sampling time,resulting in the lowest values at the third sampling stage (S3),significantly different to that in the first and second sampling stages.Moreover,abundances of the 3 genes decreased in the order narG ＞ nosZ ＞ AOA-amoA.PCA results showed the sites of S3 stage clustered together,with higher and positive PC1 scores,differed from the remaining samples.Soil organic matter,electrical conductivity,soil microbial biomass carbon,soil microbial biomass nitrogen,pH,Eh and HCl-extractable Fe (Ⅱ) were found having profound effects on the abundance of AOA-amoA,narG and nosZ genes,among which,the content of HC1extractable Fe (Ⅱ) had closest relationship with the abundance of these 3 functional genes.Significant correlations were also tested among the different environmental factors.It was concluded that nitrification and denitrification processes interacted in red paddy soil,the abundances of AOA-amoA,narG and nosZ genes decreased in the mature stage of rice,and environmental factors,especially the HCl-extractable Fe (Ⅱ),affected the AOA-amoA,narG and nosZ genes.%为了解南方红壤稻田参与土壤氮循环过程的功能微生物及其与环境因子间的普遍规律性关系,应用荧光定量PCR方法研究了稻田中不同时期氨氧化古菌氨单加氧酶编码基因AOA-amoA、硝酸盐还原酶编码基因narG和N2O还原酶编码基因nosZ基因丰度的变化,结合主成分分析(PCA)、冗余分析(RDA)探讨了有关硝化、反硝化微生物功能基因丰度变化及其与土壤环境因子间的相互关系.结果表明:AOA-amoA、narG和nosZ基因丰度间极显著正相关;AOA-amoA、narG和nosZ基因丰度随水稻生育进程逐渐降低,在早稻成熟期显著低于翻地前及早稻移栽前.土壤有机质、电导率、微生物生物量碳、微生物生物量氮、pH值、Eh及盐酸提取态Fe(Ⅱ)对AOA-amoA、narG和nosZ基因丰度的变化有重要影响,其中盐酸提取态Fe(Ⅱ)与其相关性最强.本研究探讨了红壤稻田氮转化微生物在不同时期的数量变化及其环境影响因素,为合理调控红壤稻田氮转化提供了理论依据.