The Diversity Of Bacterial Communities Of Camellia Oleifera And Its Symbiotic Relationship With Endophytic Fungi

Camellia oleifera is a peculiar woody oil crop in China,and its main product,tea oil,has high economic and edible values,and the high-quality by-products of C.oleifera husk are also used in many industries.Since a substantial number of symbiotic microorganisms exist in the plant tissues of C.oleifera,high-throughput sequencing was used in this experiment to explore the bacterial community structure and its diversity in C.oleifera roots,stems,leaves,rhizosphere soil and bulk soil,and to analyze the correlation between bacterial communities in different locations,as well as to analyze the correlation between soil physicochemical properties and total flavonoids and bacterial communities.In order to investigate the interaction between endophytic fungi and C.oleifera,four strains of endophytic fungi were isolated and purified and cultured from healthy C.oleifera roots and stems,and sterile seedlings were grown using C.oleifera seeds to reveal the interactions between endophytic fungi and C.oleifera seedlings through co-culture and the inhibitory effect of C.oleifera leaf extract on endophytic fungi in isolated culture.The main findings were as follows:1.The structure and diversity of bacterial communities in C.oleifera roots,stems,leaves,rhizosphere soil and bulk soil differed.3,127 OTUs were obtained from five species of samples,and all bacteria were found to belong to 16 phyla,58 classes,91 orders,162 families and 249 genera by sequence comparison and annotation.2.The diversity of bacterial communities in different tissues and soils showed a gradual decrease from rhizosphere soil,bulk soil,roots,stems to leaves.The functional prediction analysis revealed that the functional information of bacterial communities in different tissues and soils were different,and the highest abundance of metabolic functional flora played an important role in the production process of C.oleifera.3.The bacterial community structure of different tissues and soils were significantly correlated with C.oleifera secondary metabolites and soil physicochemical properties: soil ammoniacal nitrogen,available phosphorus and available potassium were very critical influencing factors and showed mostly significant positive correlation with bacterial communities.Total flavonoids of C.oleifera were mostly negatively correlated with bacterial communities and would inhibit the growth of bacterial communities.4.Four endophytic fungi were isolated and cultured from the rhizomes of C.oleifera and molecularly identified as Didymella sp.,Fusarium sp.,Penicillium sp.and Clonostachys rosea.5.All four fungal strains showed the ability to promote and abate the accumulation of secondary metabolites after co-cultivation with C.oleifera seedlings: all four fungal strains were able to promote the accumulation of quercetin,which was significantly greater than the control;Didymella sp,Fusarium sp.and Penicillium sp.significantly increased the leaf area and fresh weight of C.oleifera.6.The antifungal activity of C.oleifera leaf extracts was most effective against Fusarium sp.,and stopped growing at a concentration of 8.0 mg/m L.In summary,the bacterial community diversity showed a gradual decrease from rhizosphere soil,bulk soil,root,stem to leaf,and was significantly correlated with total flavonoids and soil ammoniacal nitrogen,available phosphorus and available potassium of C.oleifera.A stable symbiotic relationship exists between C.oleifera hosts and endophytic fungi,which deserves further investigation...