Isolation,identification And Growth Promotion Of Endophytic Bacteria From Two Chinese Medicinal Materials

Chinese herbs have existed in human civilization for thousands of years due to their rich medicinal value,and Yunnan Province is rich in the variety and quantity of Chinese herbal resources due to its unique geographical environment.As two important local medicinal herbs in Yunnan,[Saussurea costus(Falc.)Lipech] and [Angelica sinensis(Oliv.)Diels] have great application value and development prospect in medicinal use.In recent years,many studies have shown that medicinal plant endophytes promote the growth of host plants and stimulate the production of medicinal active substances in host plants,thus increasing the secondary metabolites of the host.The use of plant endophytic strain to develop Chinese medicinal preparations with high activity has become a hot spot of interest for scholars at home and abroad.Therefore,an in-depth study on the relationship between endophytic strain and medicinal plants is very important to improve the yield and quality of their active ingredients.The current research on Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels is mainly focused on the pharmacological effects as well as the active components,while the study on the interaction between the endophytic strain of Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels and their host plants has not been reported.In this study,two-year old healthy seedlings of Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels were used as experimental materials,and endophytic strain were isolated and identified from the roots,stems,leaves and inter-rhizosphere soil;then,all the isolated strains were analyzed for their growth-promoting biological activity,and eight endophytic bacteria that might have a growth-promoting effect on Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels were screened based on the results of the growth-promoting biological activity;Eight strains of endophytic bacteria were singly spliced back to the seedlings of Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels and the interaction between the eight strains and Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels plants was evaluated.This experiment was conducted to evaluate the growth-promoting effect in terms of whether it could promote the growth of Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels,the increase of active ingredients and the transcriptome.The main results were as follows:(1)A total of 25 endophytic bacteria in 7 genera and 14 endophytic fungi in 8 genera were isolated from the roots,stems,leaves and inter-rhizosphere soil of Saussurea costus(Falc.)Lipech;a total of 22 endophytic bacteria in 12 genera and 9 endophytic fungi in 6genera were isolated from Angelica sinensis(Oliv.)Diels;the isolated endophytic bacteria were screened for their growth-promoting ability,and it was found that different strains had different growth-promoting ability and based on the growth-promoting potential,4endophytic bacteria and 4 endophytic fungi with relatively strong growth-promoting ability were finally screened and a total of 8 endophytic bacteria were subjected to a single rejoining experiment;(2)Eight strains of endophytic strain from a single graft promoted the growth and development of Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels in different ways.For biomass XYY15,XYJ16,XYY59 promoted the biomass of Saussurea costus(Falc.)Lipech and XDY1 and ZDG1 promoted the biomass of Angelica sinensis(Oliv.)Diels.For chlorophyll,endophytic strain number XYY15,XYY59,XYJ16 and ZYJ1 were found to promote chlorophyll content in Saussurea costus(Falc.)Lipech;there was no significant difference in chlorophyll content in Angelica sinensis(Oliv.)Diels compared with the control.For the net photosynthetic rate,numbers XYY15,XYJ16,XYT115,ZYG3 and ZYJ6 significantly increased the net photosynthetic rate of Saussurea costus(Falc.)Lipech;XDY12,XDY16,ZDT5,ZDT9,and ZDY3 significantly promoted the net photosynthetic rate of light in Angelica sinensis(Oliv.)Diels;(3)Eight endophytic strain in Saussurea costus(Falc.)Lipech promoted the accumulation of active ingredients of Saussurea costus(Falc.)Lipech to different degrees;XDY12,XDY16,XDY1,ZDT9 and ZDG1 treatments in Angelica sinensis(Oliv.)Diels significantly increased the content of ferulic acid in Angelica sinensis(Oliv.)Diels and the highest endophytic bacteria was XDY12 treatment,reaching 0.083%,and the most endophytic fungi was ZDG1 treatment,reaching 0.098%;indicating that that the application of endophytic strain contributes to the accumulation of active ingredients in Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels;(4)Transcriptome data analysis showed that there were 1336 up-regulated genes and1723 down-regulated genes in Saussurea costus(Falc.)Lipech after endophytic strain treatment;there were 1715 up-regulated genes and 1454 down-regulated genes in Angelica sinensis(Oliv.)Diels,and the expression of several key genes in the synthesis pathway were increased to different degrees,which provided a theoretical basis for the study of the growth-promoting mechanism of endophytic strain on Saussurea costus(Falc.)Lipech and Angelica sinensis(Oliv.)Diels.