Study On The Relationship Between Soil Microbial Community And Soil Components And Plant Characteristics Of S. Serrata In The West Of Sichuan

Swertia mussotii Franch is a precious Tibetan medicine,which is mainly used to treat hepatobiliary disease,diuresis,heat clearing and detoxification,and has important medicinal value.The harsh growing conditions and human's large-scale picking make its wild resources nearly exhausted.Many studies have been carried out on S.mussotii,but the study on the soil microbial communities of S.mussotii is still rare.In this study,a total of 59 soil samples from three different depth soil layers(0-20 cm,20-40 cm,40-60 cm)of 20 samples of S.mussotii from four regions which include Qinghai Province(Zhongda County,Xiewu Town,Chengduo County)and Sichuan Province(Jinchuan County)were selected as the research objects.The second generation sequencing technology was used to sequence 16S rDNA of soil bacteria communities.The community structure and diversity(richness,diversity,evenness)index of bacteria communities in different depth and different areas were compared and the differences of bacteria communities in different areas were iscriminated.The differences of soil components(soil conventional composition:pH,soil moisture content,soil organic matter,TN(Total N),P,K and heavy metal composition:Fe,Pb,Cd,Ni,Cr and Cu)and plant characters including phenotype(plant height,flowering number,internode length of main stem)and active components(gentiopicrin,swertiamarin,mangiferin)were measured and compared in different regions.The relationship between bacteria communities,soil components and plant characters was discussed.The results were as follows:1.Bacterial diversity index and community structure of S.mussotii.(1)A total of 4379 bacterial OTUs were obtained,including 39 phyla,116 classes,156 orders,180 families and 213 genera.The richness of bacteria in Qinghai area was significantly higher than that in Sichuan area(P<0.05),and the difference of evenness and diversity was not significant(P>0.05).(2)There was no significant difference in diversity,evenness and richness of bacterial community among different depths in the same area(P>0.05).(3)The relative abundance of the phylum of Chloroflexi,the class of Actinobacteria and Anaerolineae,and the genus of Bradyrhizobium in Sichuan Province were significantly higher than those in Qinghai Province(P<0.05).Meanwhile,the relative abundance of the phylum of Gemmatimonadetes,the class of Thermoleophilia and Gemmatimonadetes,the order of Acidimicrobiales,and the genus of Kaistobacter in Qinghai Province were significantly higher than those in Sichuan Province(P<0.05).2.Soil composition and plant characters.(1)There was no significant difference in soil composition among different soil layers in the same area(P>0.05).The content of soil moisture,organic matter,Fe and Pb in Sichuan Province is significantly higher than that in Qinghai Province,whereas K,Cu,Ni content were significantly lower than that in Qinghai area(P<0.05).There was no significant difference in soil pH,TN,P,Cr and Cd(P>0.05).(2)The plant height,flowering number and the active components in Sichuan area were significantly higher than those in Qinghai area(P<0.05).besides,there was no significant difference in internode length of main stem(P>0.05).3.The correlation between soil bacteria community,soil components and plant characters.(1)The abundance of soil bacteria was negatively correlated with soil moisture and organic matter content,and positively correlated with altitude.The difference of bacteria was related to the difference of soil component content.Among them,there was a significant negative correlation between the phylum of Gemmatimonadetes and soil moisture content,while the class of Actinobacteria was the opposite.In addition,the phylum of Chloroflexi,the class of Gemmatimonadetes and Anaerolineae,the genus of Kaistobacter were positively correlated with Fe,K,Pb and Cu content respectively.The bacterial community structure changed significantly with soil TN,P,Pb,K,Ni and altitude,these soil components were the key environmental factors affecting the bacterial community structure.VPA analysis showed that the explanation degree of soil components to bacterial structure was 45.61%,and the explanation degree of conventional soil components(34.47%)was higher than that of heavy metals(11.14%).(2)Research showed that the plants characters were controlled by the bacterial community structure and the soil composition,and the degree was:bacterial structure>soil composition.Different levels of bacterial communities,such as the phylum of Chloroflexi,Gemmatimonadetes and the class of Anaerolineae,were the key bacterial communities that affecting plant characters.Soil composition such as soil moisture content,organic matter,Fe and Cu,were the key soil components that affecting plant characters.In conclusion,the soil bacterial community of S.mussotii were different in Sichuan and Qinghai,and interacted with the soil composition,and the phenotype and active components of the plants.This study will play a guiding role in the selection of S.mussotii natural varieties,the establishment of artificial cultivation conditions and overcoming the ecological problems such as the lack of wild resources.