Study On Root Bacterial Community Structure Of Tripterygium Wilfordii From Different Provenances

Tripterygium Wilfordii Hook.f.is an important medicinal plant in China,which has good pharmacological effects,and its root is used as medicine to treat many diseases.Plant root bacteria have various biological functions,which can promote plant growth,improve disease resistance and disease prevention ability.In this paper,the root samples of Tripterygium Wilfordii Hook.f.from different provenances and regions were collected to investigate community contructure of endophytic and rhizoshperic bacterial.To begin with,the root endophytic and rhizosphere bacteria were isolated and identified by culturable method,in order to elucidate the differences in the composition of the culturable root bacteria of Tripterygium Wilfordii Hook.f.plants among differnt proverances and regions.Subsequently,with the aim of understanding the function of active bacteria and acquiring beneficial bacteria improving growth of Tripterygium Wilfordii Hook.f.,we tested the growth promoting potential of the isolated culturable root bacteria in four aspects:indole acetic acid production,phosphate solubilization,nitrogen fixation and production of siderophores.Then the root bacterial 16S rRNA of Tripterygium ilfordii Hook.f.was sequenced based on Miseq high-throughput sequencing.The community structure and diversity of root bacteria associated with Tripterygium Wilfordii Hook.f.of different provenances and regions were analyzed,and influences of provenance and growth environment differences on root bacterial community structure of Tripterygium Wilfordii Hook.f.was explored.The main results are as follows:(1)Total 105 strains of endophytic bacteria were isolated from the root of Tripterygium Wilfordii Hook.f.,which were grouped into 2 phyla,21 genera and 50 species.The isolates in the Proteobacteria groups were the predominant,and the bacillus and the Pseudomonas were the main genera of the endophytic bacteria of the root of Tripterygium Wilfordii Hook.f..There were great differences in the population quantity and community composition of root endophytic.bacteria among Tripterygium Wilfordii Hook.from different provenances and regions.Difference in provenance appeared to have a greater effect on community compositon of root endophytic bacteria than that in habitat.In the aspect of growth promoting potential,99%of strains were able to produce indole acetic acid(IAA),33%of strains had the activity of phosphate solubilization,36.2%of strains had the ability of nitrogen fixation,and 86.7%of the strains exhibited the capability of siderophore production.13 strains showed high positivity in four kinds of growth promoting potential.Indigenous Tripterygium Wilfordii Hook.f.appeared to have higher number of functional root endophytes with plant growth promoting abilities than nonindigenous plants grown in Fujian region.(2)Total 112 strains of rhizosphere bacteria of Tripterygium Wilfordii Hook.f.were isolated,belonging to 2 groups,40 genera and 53 species.Members of the phylum Proteobacteria were the most abundant group,and Pseudomonas and Burkholderia were the dominant genera of rhizosphere bacteria of Tripterygium Wilfordii Hook.f..There were significant differences in the population and community structure of rhizosphere bacteria among Tripterygium Wilfordii Hook.f.from different provenances and regions.The strains producing IAA,phosphate solubilization,nitrogen fixation and siderophore production accounted for 96.4%,36.6%,33.9%and 91.1%respectively,and 14 rhizosphere bacteria had the four growth promoting characteristics.(3)Through high throughput sequencing of Miseq,endophytic bacteria of Tripterygium Wilfordii Hook.f.were classified as 5254 OTUs,belonging to 42 phyla,89 classes,207 orders,420 families,834 generaand 1669 species.The dominant phyla were Cyanobacteria,Proteobacteria and Actinobacteria,and the main genera were norank-c-Cyanobacteria,Acidothermus and Ralstonia.The endophytic bacterial community structure of Tripterygium Wilfordii Hook.f.was more influenced by plant provenance than that growth environment.(4)By sequencing on the Illumina Miseq platform,the rhizosphere bacteria of Tripterygium Wilfordii Hook.f.were classified into 6812 OTUs,which were belonged to 46 phyla,46 classes,96 orders,414 families,809 genera and 1719 species.Proteobacteria,Acidobacteria and Actinobacteria were the dominant phyla of rhizosphere bacteria,and the Burkholderiaceae,Acidobacteriaceae-Subgroup-1 and norank-c-Cyanobacteria were the main families.The rhizosphere bacterial community structure of Tripterygium Wilfordii Hook.f.was more influenced by growth environment than plant by plant provenance.There were great differences in bacterial community composition and structure between root endophytic and rhizospheric bacteria of Tripterygium Wilfordii Hook.f..The analysis of the relationship between rhizosphere bacterial community distribution of Tripterygium Wilfordii Hook.f.and chemistry of soils indicated that the community structure was significantly correlated with available phosphorus,pH,alkaline nitrogen,available potassium and total carbon.To sum up,the root endophytic and rhizospheric bacteria of Tripterygium Wilfordii Hook.f.from different provenances and regions were rich in diversity.There were great differences in the community structure between endophytic and rhizospheric bacteria of Tripterygium Wilfordii Hook.f.from different provenances and regions.