| Plant domestication and breeding are the basis for emergence and development of agriculture and have a tremendous impact on human social civilization.The narrow genetic background of modern varieties is gradually becoming a major bottleneck of crop breeding,but the crop wild relatives can provide valuable genes resources for crop domestication and breeding.Rhizosphere microbes have been confirmed to give more stress resistance and ecological functions to plants.However,it is unclear whether domestication affects the assembly and functions of rhizosphere microbial communities.This paper was focused on the root compartmnet of wild,semi-wild,cultivated and eurytopic soybeans that were planted in different soils from northeast(NER),Huanghuaihai(HR)and southern(SR)and investigated the structure and composition of microbial communities in root zone,rhizosphere and root,and analysed the differences of rhizosphere microbial communities among soybean accessions,and explored the effects of soybean accession on nodule endophytic bacteria by he high-throughput sequencing.The results were as follows:(1)Soybean root associated microbial community is mainly affected by soil type,root compartments,and soybean accession.There are significant differences in soybean microbial communities in NER,HHR and SR.From the root outer to inner,the species richness and diversity of microbes gradually decreased,the significant difference of OTUs gradually increased,and different soybean accession microhabitat had their own selective filtering effects on OTUs.Through network analysis,it was found that root endosphere barterial network structure of wild soybeans is more complicated,and rhizosphere bacterial network structure of semi-wild,cultivated and eutrytopic soybeans was more complex,and the root endosphere microbial community is more susceptible to soybean accession,and the keystones of the root zone,rhizosphere and root are different.(2)The rhizosphere microbial community structure of soybean accssion was significantly different in different soils.From wild,semi-wild,cultivated to eurytopic soybean accession,the species richness and diversity of rhizosphere bacteria gradually decreased in NER,.but the change of species richness and diversity is opposite in HR and SR.The proportion of the core OTUs numbers in soybean was small,but its relative abundance was high.Different soybean accessions shared-core groups include Ensifer,Bradyrhizobium,Mesorhizobium,Rhizobium,Pseudomonas,Novosphingobium,Sphingomonas,Massilia,Piscinibacter.,Pseudoduganella,Ramlibacter,Variovorax and two unclassified OTUs.The phenotype of soybean was significantly correlated with the rhizosphere microbial community.The plant whole length was significantly positively correlated with the relative abundance of wild soybean rhizosphere microbes,and the fresh weight was significantly negatively correlated with relative abundance of cultivated soybean rhizosphere microbes.(3)The soybean nodule endophytic community difference was significant,and it was mainly affected by soil type,followed by soybean accession.Along the trajectories of wild,semi-wild,cultivated and eurytopic soybeans,the endophytic richness and diversity of nodules gradually increased.We divided the endophytic bacteria into symbiotic rhizobium community and non-symbiotic community.It was found that Bradyrhizobium dominated among the symbiotic rhizobial communities in NER and SR,and Ensifer dominated among the non-symbiotic rhizobial community in HR.Bradyrhizobiaceaeare,Comamonadaceae,Sphingomonadaceae,Rhizobiaceae and Enterobacteriaceae were main families among the non-symbiotic nodule endophytic community.This study revealed the microbial community assembly rules of wild,semi-wild,cultivated and widely cultivated soybean and the factors in affecting the diversity of nodule endophytic communities.Therefore it will lay a foundation for the recovery and utilization of soybean beneficial microbes and providd new pathways for future breeding. |
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