Effects of Transgenic DREB Toybean Dongnong50 on Diversity of Soil Nitrogen-fixing Bacteria

Drought is a bottleneck for worldwide soybean production which is getting more serious as the climate continues to worsen. Dehydration responsive element binding（DREB） is a kind of transcription factor that regulates the expression of stress tolerance-related genes in response to drought, high salinity and cold stress in plant. Soybean with DREB gene possesses the drought resisting capability which is helpful to increase the yield. However, the potential risk of genetically modified plants（GMPs） on soil microbial community is still in debate. In order to understand the effects of transgenic DREB soybean on the nitrogen-fixing bacteria, the diversity of nif H gene in pot experiments planted transgenic soybean and near-isogenic nontransgenic soybean under normal water condition and drought stress condition was analyzed by PCR-DGGE and sequence analysis. The results showed that transgenic soybean under normal water condition decrease the diversity of the nitrogen-fixing bacteria in the seeding stage and flowering stage, but had no notable effect in other stages. Under drought stress, transgenic soybean reduced the diversity of the nitrogen-fixing bacteria in the flowering stage, but had no notable effects on other stages. Phylogenic analysis revealed that g7, g13, g15 and g19 had a close relationship with Alphaproteobacteria, g12 had a close relationship with Azonexus, others were related to Betaproteobacteria and Burkholderia.

Effects of interactions between arbuscular mycorrhizal fungi and bacteria on the growth of Lotus corniculatus L.:From the perspective of regulating rhizosphere fungal community

Arbuscular mycorrhizal fungi(AMF)provide essential nutrients to crops and are affected by fertilizers.Phosphate-solubilizing bacteria(PSB),nitrogen-fixing bacteria(NFB),and AMF have mutually beneficial relationships with plants,but the effects of their interactions on plant growth by regulating rhizosphere fungal community have not been sufficiently studied.In this study,a greenhouse pot experiment was conducted to investigate the interactions between AMF and bacteria(PSB and NFB)on the growth of Lotus corniculatus L.Specifically,the role of rhizosphere fungal community in the growth of Lotus corniculatus L.was explored using Illumina MiSeq high-throughput sequencing.The results showed that combined inoculation of AMF with PSB and NFB increased plant biomass,plant height,and fungal colonization rate.The richness,complexity,and stability of rhizosphere fungal community also increased after combined inoculation of AMF with PSB and/or NFB,particularly with PSB.In addition,combined inoculation of AMF with PSB and NFB enriched the abundance of beneficial microorganisms,with Chaetomium and Humicola showing the greatest alterations.The structural equation model showed that the interactions of AMF with PSB and NFB promoted plant growth by affecting fungal network structure and soil enzyme activities involved in carbon,nitrogen,and phosphorus cycling.These findings provide evidence for the effects of interactions of AMF with PSB and NFB on rhizosphere fungal community and plant growth.