燕麦/大豆和燕麦/花生间作对根际土壤固氮细菌多样性与群落结构的影响
Effects of oat-soybean and oat-groundnut intercropping on the diversity and community composition of soil nitrogen-fixing bacterial in rhizosphere soil

运用PCR-DGGE技术研究燕麦/豆科不同间作组合和单作处理对根际土壤固氮细菌的群落结构及多样性的影响。结果表明:不同生育时期,单作燕麦根际固氮微生物群落结构存在明显差异;在间作系统中,除灌浆期差异显著外,间作燕麦根际固氮微生物群落比较稳定。在整个生育期,间作豆科作物相对于其单作,根际固氮微生物群落较为接近。间作系统中作物根际固氮微生物群落结构更为稳定,变化幅度小,或趋于一致,尤其在燕麦/大豆间作系统中表现更为突出。DGGE条带测序可知,燕麦的根际固氮微生物都属于变形菌门,主要为α-变形菌纲的慢生根瘤菌属、β-变形菌纲的Azohydromonas和少数其他菌属。豆科作物根际固氮细菌种类较丰富,主要为α-变形菌纲的慢生根瘤菌属、β-变形菌纲的Azohydromonas和Pseudacidovorax、γ-变形菌纲的克雷白氏杆菌属及少数Cyanobacteri和一些不可培养固氮菌群,且存在一些燕麦根际不存在的菌属,如鱼腥藻属和Ideonella。总体来看,燕麦/豆科间作能够影响作物根际土壤固氮菌的群落结构,有助于深化对燕麦合理间作栽培模式的认识。
Being an indicator of environment variation,nitrogen-fixing bacterial community is very sensitive to the variation of environment.But the relationship between those two is unclear.This study aimed to investigate the variation of nitrogen-fixing bacterial community diversity responded to different intercropping systems by targeting nifH gene.Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE) and DNA clone technology were employed to investigate the variation of nitrogen-fixing bacterial community in rhizosphere soil as affected by oat/soybean intercropping,oat/groundnut intercropping and monocropping of these three crops.Principal component analysis indicated that nitrogen-fixing bacterial community in rhizosphere soil was relatively stable and barely changed within the intercropping system,especially in oat-soybean intercropping system.Based on the DGGE bands sequencing and Phylogenetic analysis of nifH gene,nitrogen fixing microbes mainly affiliated to Bradyrhizobium Jordan of α-Proteobacteria,Azohydromonas of β-Proteobacteria,and few other species.The rhizosphere of beans had a complicated composition,including B.Jordan of α-Proteobacteria,Azohydromonas and Pseudacidovorax of β-Proteobacteria,Klebsiella pneumonia of γ-Proteobacteria,Cyanobacteri and some uncultured bacteria.In conclusion,the oat-beans intercropping systems had effects on the diversity and community structure of nitrogen-fixing bacteria in the rhizosphere of plants.It would help us to understand the positive effects of oat-beans intercropping.