Study On The Potential Mechanism Of Rhizosphere Microorganisms Shaping The Authenticity Of Litsea Cubeba Based On Keystone Species Theor

Geoherbalism is an important role of the medicinal herbs properties and the private characteristic of traditional Chinese medicine.Geoherbalism formation is mainly interaction both species genetic and external environmental factors,is a reflects the"Chinese medicinal materials quality&clinical efficacy"relationship.As the synonym of good quality traditional Chinese medicine,Daodi herbs are the carrier of geoherbalism and the important theory of traditional Chinese medicine in evaluating the quality of herb.Our previous studies have shown that rhizosphere microbial is the key biotic factor shaping the formation of geoherbalism of Cinnamomum migao fruit,but how to explore which keystone taxa of microbial communities affect the geoherbalism of traditional Chinese medicine is still pending.C.migao fruit is a famous daodi herbs and ethnic traditional medicinal material in Guizhou province of China,in our previous studies found that rhizosphere microbial may be the dominant biotic factor in the formation of the geoherbalism of C.migao fruit.Meanwhile,we also found that the keystone taxa theory was very similar to the traditional Chinese medicine geoherbalism theory.We believed that the geoherbalism theory would help us to find the functional keystone taxa in the rhizosphere microbial community.In this study,we collected 86 individuals of all known populations of C.migao for two-year sampling.A total of 344 samples of rhizosphere soil and bulk soil were collected,and 67 samples of C.migao fruit were collected（C.migao was a phenomenon of alternate bearing,and part populations had fruits failed）.Through high-throughput sequencing to analyze soil microbial diversity,GC-MS to analyze metabonomic of C.migao fruit,intermittent chemical analysis of soil nutrients,and collection of climate data,comprehensive research was carried out to determine the keystone taxa and potential mechanisms for rhizosphere microbial to influential C.migao fruit geoherbalism.The following question were mainly discussed:（1）The chemical properties of rhizosphere and bulk soil including nutrients,enzymes,SOC and p H were determined under the two-year time series of genuine&non-genuine populations to explore the differences;（2）The difference of metabolic compounds between genuine and non-genuine populations of C.migao fruit;（3）Characteristics of rhizosphere&bulk soil microbial communities in genuine&non-genuine populations of C.migao;（4）The recruitment process and assembly mechanism of plant roots to bulk soil microbial;（5）Explore of keystone taxa of soil microbial community and their function on the accumulation of metabolites in the host fruit C.migao.Our results show that:（1）In general,the content of total and available nutrients in the rhizosphere soil is higher than that in the bulk soil,the p H in the rhizosphere was lower,the content of SOC in the rhizosphere is higher than that bulk soil,and the soil enzyme in the rhizosphere is higher activity than that in the bulk soil.However,only from the perspective of genuine and non-genuine populations,there is no significance differences in the composition,which indicates that the not differences of soil chemical properties in large scale space.（2）The results of SFE-CO₂showed that the content of volatile oil was between 18%and 33%,which indicated that there was rich volatile oil in C.migao fruit,and the content of volatile oil in genuine populations was significantly higher than that in non-genuine populations.The results of the metabonomic characteristics of volatile oil also showed that there were significant differences between genuine and non-genuine populations,1,4,7,-Cycloundecatriene,1,5,9,9-tetramethyl-,Z,Z,Z-,beta copaene,ans bicyclogermane,a terpenoid compound,could be used as a differential identification metabolite between genuine and non-genuine populations of C.migao,and could be divided into 3 chemical types along the features.（3）There are abundant microbial communities in the rhizosphere soil and bulk soil in C.migao.A total of 56 phyla,66 classes,193 families,608genus of bacteria have been annotated.Acidobacter,AD3,Chloroflexi and WPS2 are the dominant taxa in the rhizosphere and bulk soil bacterial communities.A total of 16 phyla,63 classes,160orders,393 families and 120 genus of fungi are annotated.（4）As a subset of bulk soil microbial,the rhizosphere microbial of C.migao,are very similar at phylum classification level,but their species composition differences become more obvious with the more higher classification level,but the consistent trend is not high in different locations.The functions of rhizosphere microbial and bulk soil microbial are obviously different.The ecology functions of rhizosphere microbial are closely related to nitrogen and carbon cycling processes,and bulk soil microbial in different environments are highly diversified.（5）A large number of potential keystone taxa were identified from rhizosphere and bulk soil microbial used different methods.The number of shared keystone taxa detected based on module centrality was the maximum,with only 81 ASVs in bulk soil microbial communities and 110 ASVs in rhizosphere microbial communities.A large number of keystone taxa were also identified in subnetwork,connectivity,specificity occupancy.From the perspective of recognition capability,module centrality and subnet recognition are more accurate.Meanwhile,a partly functional taxa in the keystone taxa are highly related to the metabolites of C.migao fruit,including Bradyrhizobium,Bradyrhizobium,and Rhodoplane keystone taxa highly related to the nitrogen cycle.Meanwhile,the results of structural equation model（SEM）also revealed the regulatory relationship of soil nutrients of the metabolite compounds of C.migao fruit.It was confirmed that the formation of the keystone taxa on the geoherbalism of the C.migao fruit was through by affecting the soil nutrients.In this study,the geoherbalism theory of traditional Chinese medicine and ecological theory are combined to find out the keystone functional taxa that shape the geoherbalism of C.migao from a large number of microbial communities.Meanwhile,the potential mechanism of keystone functional taxa is determined in combination with climate,soil factors,which brings new insights into the later determination of the formation mechanism of the quality of geoherbalism medicinal materials dominated by microbial.