The Role of Endophytic/Epiphytic Bacterial Constituents in the Immunostimulatory Activity of the Botanical, Astragalus membranaceus.

Astragalus membranaceus is a staple of Traditional Chinese Medicine being one of the oldest medicinal herbs listed in the material medica of Chinese herbal medicine. Chinese herbalists have used Astragalus to help the human body fight a variety of diseases. Modern herbalists utilize Astragalus primarily as an immunostimulant to prevent common infection and aid in the recovery following infection. Historically, the biological activities associated with Astragalus have been accounted for, at least in part, to several constituents present in the botanical including saponins and polysaccharides. We propose that in addition to these constituents, compounds from endophytic (or epiphytic) bacteria present in (or on) the roots of Astragalus may have an important biological role. Lipopolysaccharides and lipoproteins are major components of Gram-negative bacteria and highly potent activators of the innate immune response. Our data supports a direct correlation between the level of immune gene induction and the level of lipopolysaccharides/lipoproteins present in the Astragalus extract. We demonstrate that extracts from Astragalus specifically activate Toll-like and NOD-like receptors involved in the recognition and response to bacterial constituents and that removal of the lipopolysaccharide/lipoprotein from the Astragalus extract reduced the level of this response. The results support that many immune enhancing botanicals have established a symbiotic relationship with Gram-negative bacteria and that the immune enhancing effect of these botanical extracts on the body may not only be due to endogenous plant compounds, but endophytic (or epiphytic) bacterial components as well.

Enhanced Production of Two Bioactive Isoflavone Aglycones in Astragalus membranaceus Hairy Root Cultures by Combining Deglycosylation and Elicitation of Immobilized Edible Aspergillus niger.

A cocultivation system of Astragalus membranaceus hairy root cultures (AMHRCs) and immobilized food-grade fungi was established for the enhanced production of calycosin (CA) and formononetin (FO). The highest accumulations of CA (730.88 ± 63.72 µg/g DW) and FO (1119.42 ± 95.85 µg/g DW) were achieved in 34 day-old AMHRCs cocultured with immobilized A. niger (IAN) for 54 h, which were 7.72- and 18.78-fold higher than CA and FO in nontreated control, respectively. IAN deglycosylation could promote the formation of CA and FO by conversion of their glycoside precursors. IAN elicitation could intensify the generation of endogenous signal molecules involved in plant defense response, which contributed to the significantly up-regulated expression of genes in CA and FO biosynthetic pathway. Overall, the coupled culture of IAN and AMHRCs offered a promising and effective in vitro approach to enhance the production of two health-promoting isoflavone aglycones for possible nutraceutical and pharmaceutical uses.

Geodermatophilus ruber sp. nov., isolated from rhizosphere soil of a medicinal plant.

A novel actinobacterial strain, designated CPCC 201356(T), was isolated from a rhizosphere soil sample of the medicinal plant Astragalus membranaceus and subjected to a polyphasic taxonomic analysis. Good growth occurred at 20-32 °C, at pH 7.0-7.5 and with 0-1 % (w/v) NaCl. Colonies on R2A and ISP 2 agar were light red to red, round and lacked aerial mycelium; cells adhered to the agar. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinones were MK-9(H(4)) and MK-9. Polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine and two unknown phospholipids. The major cellular fatty acids were iso-C(16 : 0), iso-C(15 : 0) and C(17 : 1)ω8c. The G+C content of the genomic DNA was 72.8 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain CPCC 201356(T) belonged to the family Geodermatophilaceae and consistently formed a distinct sub-branch with Geodermatophilus obscurus DSM 43160(T). The organism showed 16S rRNA gene sequence similarity of 97.7 % with G. obscurus DSM 43160(T). DNA-DNA hybridization between strain CPCC 201356(T) and G. obscurus DSM 43160(T) was 17.4 %. On the basis of evidence from this polyphasic taxonomic study, a novel species, Geodermatophilus ruber sp. nov., is proposed; the type strain is CPCC 201356(T) (=DSM 45317(T) =CCM 7619(T)).

[Study on difference of biological characteristics and resistance to powdery mildew of different Astragalus populations].

OBJECTIVE: To study difference among populations which belong to Astragalus membranaceus and A. membranaceus var. mongholicus on morphology, habit, characteristics of physiology and resistance to powdery mildew, and classify them in order to provide theoretical basis for breeding and improving varieties. METHOD: Morphology, habits, isozyme and soluble protein electrophoretograms were compared among the populations. They were categorized by cluster analysis based on those electrophoretograms. Different ability of resistance to powdery mildew was also studied through comparing disease indices among six populations. RESULT: The results showed A. membranaceus var. mongholicus was distinctly different from A. membranaceus. There was a special type in colonies of A. membranaceus, which showed hairy upper epidermis of leaflets and later florescence. CONCLUSION: Astragalus for medicine could be categorized in three types A. membranaceus var. mongholicus, A. membranaceus early florescence type and A. membranaceus late florescence type. Among them A. membranaceus var. mongholicus is most resistant to powdery mildew, while A. membranaceus is easily infected, and the early florescence type is even more easily infected.

[Presearch on preventing the medicinal plant diseases with Trichoderma harzianum preparation].

OBJECTIVE: To control the medicinal plant diseases with the preparation of Trichoderma harzianum. METHOD: Antagonistic action of the preparation to the pathogens of the medicinal plants in vitro, and controling effects of the preparation on these diseases in greenhouse and in the field were tested. RESULT: The test in vitro showed that Trichoderma harzianum, used as a biocontrol factor, had stronger antagonistic action to Fusarium equiseti, Sclerotinia sp. and Rhizoctonia solani which were the medicinal plant pathogens of Astragalus membranaceus, Glehnia littoralis and Panax quinquefolium respectively. Biological controling effects on sclerotium root rot of Glehnia littoralis were 83.6% and 72.5% respectively in greenhouse and in the field with the preparation of Trichoderma harzianum. And controling effects on root rot of Astragalus membranaceus and seedling damping-off of Panax quinquefolium were 80% and 60% respectively in the field. The dosage of the preparation used in the field was 10 g.m-2. CONCLUSION: The preparation of Trichoderma harzianum can be used as a substitute for such chemicals as Carbendazim. Using the preparation to control medicinal plant diseases provides a technical safeguard for the good agricultural practice of medicinal plants.