Effects And Regulation Of Endophytic Fungal Elicitors From Bletilla Striata On Host Growth And Main Substances

Bletilla striata(Thunb.)Reichb.F.usually uses its pseudo bulb as the main drug site.In order to regulate the target substance yield and improve the active ingredients of Bletilla st.riata,endophytic fungal elicitors were symbiotic with Bletilla striata tissue culture seedlings.Then,according to plant growth traits,total phenolic content,and total polysaccharide content,a strain that was most effectively promoted and produced active substances was screened,and their mycelia were separately selected.Fermentation broth,and further protein and polysaccharide extracts isolated from mycelium were symbiotically cultured with tissue culture seedlings to explore the regulation of signal molecules and secondary metabolic key enzymes in Bletilla striata,and the correlation with total phenolic content.The main results are as follows:(1)The endophytic fungal elicitor and Bletilla striata tissue culture seedlings were symbiotic,and the fresh weight growth of the tissue cultured seedlings after treatment with the strain 1-N2 elicitor was 2.45 g,and the total phenolic content of the bulb was 4.59 mg/g,the total polysaccharide content of the bulb was 12.42%.Therefore,the endophytic 1-N2 elicitor was screened to promote the growth of Bletilla striata sprouts and roots.(2)After the mycelium and fermentation broth of endophytic fungus 1-N2 were symbiotic with Bletilla striata tissue culture seedlings,the content of H2O2 and NO in addition to salicylic acid in the process of changing the signal molecule content of the two groups of treatments The maximum time is consistent.In the samples treated with the fermentation broth,the maximum expression times of the three secondary metabolic key enzymes,phenylalanine ammonia lyase,tyrosine carboxylase and cinnamate-4-hydroxylase,were the 20th day and the 12th day.On day 4 and day 4,the three key enzyme activities in the mycelium treated samples were significantly expressed on the 16th day,which may be parallel.The total phenolic content of the tissue culture seedlings after mycelium treatment was higher than that of the fermentation broth.The mycelium treated samples had the highest total phenolic content at 4.55 mg/g on the 16th day,which was related to the expression of key enzyme activities.It is indicated that the 16th day is the best period for inducing the total phenolic content of Bletilla striata in the mycelium treatment group.The three key enzymes of secondary metabolism were also significantly correlated with the changes in total phenolic content of the mycelium-treated Bletilla striata tissue culture seedlings.(3)After the protein and polysaccharide extracts isolated from the endophytic fungus 1-N2 mycelium were symbiotically cultured with Bletilla striata tissue culture seedlings,the order of the maximum value of the signal molecules in the two groups was identical,which was H2O2,NO,SA.In the protein-treated samples,the maximum expression times of three secondary metabolic key enzymes,phenylalanine ammonia-lyase,tyrosine carboxylase,and cinnamate-4-hydroxylase,were 20th,12th and 12th;the maximum expression time of three key enzymes,phenylalanine ammonia lyase,tyrosine carboxylase and cinnamate-4-hydroxylase,in the samples treated with polysaccharide extract were the 16th day,the 16th day,the 8th day.The total phenolic content of the samples treated with the polysaccharide extract was 4.26 mg/g on day 16 and higher than that of the protein treatment group,indicating that the optimal time for inducing the total phenol of Bletilla striata in the polysaccharide extract treatment group was the 16th day.