低甲烷排放转基因水稻对土壤微生物群落的影响

Effect of low-methane transgenic rice on microbial communities in paddy soil

低甲烷排放转基因水稻是实现水稻低碳生产的理想材料。土壤微生物驱动了稻田甲烷的产生,低甲烷排放转基因水稻土壤微生物群落组成的变化不仅影响稻田甲烷排放,也关系到土壤微生态系统的稳定性。通过对细菌16S rRNA基因、真菌ITS基因的高通量测序及mcrA、nifH、amoA和nirS等功能基因的荧光定量PCR,分析了低甲烷排放转基因水稻(86R27-3)与野生型水稻(MH86)土壤微生物群落间的差异。结果显示:稻田土壤细菌群落的α-多样性指数在86R27-3与MH86间无明显差异,且仅在水稻分蘖期86R27-3的土壤真菌群落多样性指数Shannon、Simpson及均匀度指数Pielou_e显著高于MH86(P<0.05);β-多样性分析表明土壤细菌或真菌群落组成在86R27-3与MH86间均没有显著差异;但在水稻齐穗期:86R27-3土壤的放线菌门(Actinobacteria)、罗泽真菌门(Rozellomycota)的相对丰度显著高于MH86(P<0.05),而酸杆菌门(Acidibacteria)、子囊菌门(Ascomycota)的相对丰度显著低于MH86(P<0.05);土壤微生物群落功能预测显示,86R27-3土壤氮、硫和锰代谢细菌功能群丰度显著低于MH86(P<0.05),如分蘖期的土壤硝酸盐还原、硝酸盐呼吸、硫代硫酸盐呼吸及硫呼吸,齐穗期和成熟期的好氧亚硝酸盐氧化及成熟期的锰氧化等;与MH86相比,86R27-3的土壤真菌功能群丰度有减有增,如在水稻不同生育期内的其未定义腐生物银耳目、嗜热囊菌科、镰刀菌属及韦斯特氏菌功能群丰度显著降低(P<0.05),而其分蘖期的动物内共生体腐生生物毕赤酵母属和未定义腐生物马勃科功能群丰度显著提高(P<0.05)。定量PCR分析表明86R27-3土壤中的产甲烷细菌mcrA基因丰度显著低于MH86(P<0.05),同时,土壤固氮菌nifH基因、氨氧化细菌amoA基因及反硝化细菌nirS基因的丰度在86R27-3土壤中也显著降低(P<0.05)。综上所述,低甲烷排放转基因水稻(86R27-3)对土壤细菌或真菌的群落组成没有影响,但可引起主要细菌或真菌种类的相对丰度及某些细菌或真菌功能群丰度发生变化,并显著降低了稻田土壤微生物功能基因丰度。

The low-methane transgenic rice is an ideal rice material for low-carbon production of rice.The production of methane is driven by microorganisms in paddy soil.Changes in soil microbial community composition of low methane emission transgenic rice not only affect paddy field methane emission,but also affect the stability of soil microbiological system.In this study,the differences of microbial communities and the abundance of functional genes in paddy soil with between low-methane transgenic rice(86R27-3)and wild-type rice(MH86)were analyzed by high-throughput sequencing of 16S rRNA gene or ITS gene and fluorescence quantitative PCR of functional genes,such as mcrA、nifH、amoA and nirS.The results showed that there were no differences in α-diversity of bacterial communities in paddy soil with between 86R27-3 and MH86,and the α-diversity of Shannon,Simpson and Pielou_e index of fungal communities in paddy soil with 86R27-3 were higher than those of MH86 only under the tillering stage of rice.The differences in the community composition of bacteria or fungi in paddy soil with between 86R27-3 and MH86 were also not obvious based on the analysis of β-diversity of microbial communities.However,under the heading stage of rice,the relative abundance of Actinobacteria or Rozellomycota in paddy soil of 86R27-3 was significantly higher(P<0.05)than that of MH86,and the relative abundance of Acidibacteria or Ascomycota in paddy soil of 86R27-3 was significantly lower(P<0.05)than that of MH86.The functional prediction of soil microbial community showed that the abundance of bacterial functional groups for soil metabolism of nitrogen,sulfur or manganese in 86R27-3 was significantly lower than that of MH86(P<0.05),such as nitrate reduction,nitrate respiration,thiosulfate and sulfur respiration under the tillering stage of rice,aerobic nitrite oxidation under the heading and maturation stages of rice or manganese oxidation at maturation stage of rice.Compared with MH86,there were decrease and increase in the abundance of soil fungal functional groups of 86R27-3,such as the abundance of its Undefined Saprotroph of Tremellales,Pseudeurotium,Fusarium and Westerdykella significantly decreased(P<0.05)under different growth periods of rice,while the abundance of its Animal Endosymbiont-Undefined Saprotroph of Pichia and Undefined Saprotrophthe of Lasiosphaeriaceae significantly increased(P<0.05)under tiller stage of rice(P<0.05).Quantitative PCR analysis of microbial functional genes showed that the abundance of methanogenic bacterial mcrA gene in paddy soil of 86R27-3 was significantly lower(P<0.05)than that of MH86;and the abundance of nitrogen-fixing bacterial nifH gene,ammonia-oxidizing bacterial amoA gene and denitrifying bacterial nirS gene were also significantly reduced(P<0.05)in paddy soil of 86R27-3.In conclusion,low-methane emission transgenic rice(86R27-3)had no significant impact on the composition of soil bacteria or fungal communities,but could change the relative abundance of major species of bacteria or fungi and the abundance of some bacterial or fungal functional groups,and significantly reduce the abundance of microbial functional genes in paddy soil.