The Preliminary Study On Diversity Of Endophytic Bacteria And Their Correlation With Secondary Metabolites In Different Ecological Regions Of Jiangsu Province

Ginkgo biloba(G.biloba)is a valuable rare medicinal and megaphanerophyte widely spread in Jiangsu region.It is well known that G.biloba leaves contain sorts of natural products like flavonoids and Ginkgolides which derive from plant-secondary metabolism pathway.The efficiency and quality of G.biloba extract(GBE)are directly related to the content and types of the secondary metabolites in leaves.Interestly,endophytes such as endophytic bacteria were found contribute to plant secondly metabolism,but the detailed function for plant natural products is not clear especially in G.biloba.Studies figure out that endophtic microorganisms live in G.biloba tissue or cells,and co-evoluted with G.biloba,after a long period of coexistence and gradually formed a mutualistic symbiotic relationship.Other studies indicated that endophytic bacteria can produce the same or similar secondary metabolites within these tissues.But it has not been deeply studied whether endophytic bacteria from G.biloba can affect host to produce secondary metabolites and their interactions.Studying on the correlation between the diversity of endophytic bacteria and the content of secondary metabolites in G.biloba can dig out the potential correlationship between them with the help of modern statistical analysis.This research can also support our previous studies that endophytic bacteria can improve the content of effective secondary metabolites in leaves of G.biloba.Jiangsu province located in the mid-east coast of China,climate type transits from temperate to subtropical gradually.Jiangsu province is one of the main plantareas of G.biloba in China.According to the differences of ecological factors such as climate conditions,Jiangsu province can be divided into four ecological regions.In this study,different tissues of G.biloba from different ecological regions were collected to analyze the diversity of endophytic bacterial community in G.biloba by the next generation sequencing technique.And the plant related secondly metabolism products were measured by GC-MS and HPLC-ELSD,and then obtained the concentrations of secondary metabolites.Facing the two different data set and trying to find out the inner link between these data cannot without statistical analysis.So,in our study we introduced R as analyzing tool for the correlation between endophytic bacterial diversity and secondary metabolism in the G.biloba leaves.The main results as below:1.The diversity and community structure of endophytic bacteria in different ecological regions were measured and analyzed by high-throughput sequencing technology.The main analysis indexes include OTU clustering,taxonomic analysis,diversity index,Shannon-Wiener curve and Rank-Abundance curve.(1)G.biloba endophytic bacterial community diversity in the coastal ecological region is the most abundant,distributed in 53 classes,which in North of Jiangsu ecological region(north ecological region)is lowest,distributed in 31 classes.Meanwhile,G.biloba endophytic bacterial community diversity in South of Jiangsu ecological region(south ecological region)is similar to the middle ecological region,distributed in 47 and 42 classes.(2)Comparing with stems and leaves of G.biloba,the high diversity of endophytic bacteria were found in roots which suggested that influenced by the large pool of soil microorganisms.(3)The diversity and the community structure of endophytic bacteria in the leaf and stem tissues is similar.2.The types and content of secondary metabolites in leaves of G.biloba in four ecological regions were determined.Puny polar components in leaves of G.biloba were analyzed by GC-MS method.The content of total flavonoids was determined by UV Spectrophotometry.The content of ginkgolideA,ginkgolide B and ginkgolide C is determined by HPLC-ELSD method.The content of polysaccharides in leaves of G.biloba and the monosaccharide composition of polysaccharides were determined.(1)126 kinds of puny polar components are obtained: 58 kinds in south ecological region,55 kinds in middle ecological region,48 kinds in coastal ecological region and 68 kinds in north ecological region.The kinds of puny polar components in north ecological region is the most abundant,while the coastal ecological region is the least.(2)The content of total flavonoids in leaves of G.biloba in south ecological region is the highest.The content in other three ecological region are closed.(3)The content of ginkgolide A in south and middle ecological regions are relatively higher.The content of ginkgolide B are closed in middle,coastal and north ecological regions.(4)The content of polysaccharide in north ecological region is the highest.The content in middle and coastal ecological regions are closed.3.Using R language to analyze the correlation between G.biloba endophytic bacterial diversity and secondary metabolism in the leaves of Jiangsu Province.(1)The most significant correlation with the accumulation of secondary metabolites are the endophytic bacteria distributed in Gammaproteobacteria.These bacteria have significant correlation with the content of total flavonoids,ginkgolides A and ginkgolide B,correlation index are 0.94,0.76 and-0.96.(2)The content of G.biloba polysaccharide has the most wide correlation between the relative abundance of endophytic bacteria.The content has significant correlation with 7 classes of endophytic bacteria,the highest correlation is Clostridia,coefficient index is-0.98.