RESUMO
ObjectiveTo develop safe and effective microbial agents against Panax ginseng root rot. MethodP. notoginseng endophytes were screened in plate confrontation tests， followed by morphological and molecular biological identification of antagonistic strains， optimization of strain fermentation conditions in a single factor test， and determination of optimal carriers and auxiliary agents of the microbial agent and their ratio using response surface methodology for formulating the production process. The prevention and control effects of the microbial agent were verified in the confrontation and pot culture experiments. ResultThe plate confrontation test yielded a strain named Fusarium pseudoanthophilum with significant resistance to root rot， and its antibacterial rate was 53.33%. According to the single factor test， the fermentation conditions of F. pseudoanthophilum were determined to be fermentation time 60 h， fermentation temperature 26 ℃， speed 120 r·min-1， and pH 6.5. The response surface optimization results showed that the number of viable bacteria reached the maximum （5.23×109 cfu·g-1） when the peat was 60.00 g， sodium carboxymethylcellulose 3.50 g， and sodium alginate 4.76 g. The influences of carriers and auxiliary agents on the number of viable bacteria were sorted by degree in a descending order as follows： peat>sodium carboxymethylcellulose >sodium alginate. The confrontation test results showed that when the microbial agent concentration was greater than 1.00 g·L-1， it had a significant inhibitory effect on the root rot pathogen F. oxysporum and the inhibitory rate was more than 42.3%. As demonstrated by the pot culture experiment， the inoculation of biocontrol agent for 28 d significantly reduced the incidence （66.99%） of root rot in P. ginseng seedlings and disease index （61.69%） and increased their leaf length （33.04%） and fresh weight （34.48%）. ConclusionF. pseudoanthophilum inoculant is efficient in preventing and controlling the root rot， making it worthy of further development and utilization.
RESUMO
Dammarane saponins, classified as tetracyclic triterpenoid saponins, are major components of Panax ginseng, P. notoginseng, P. quinquefolium, and Gynostemma pentaphyllum. The results of recent research have demonstrated that the dammarane saponins have a significant effect on regulating blood glucose, which provides the important value in the prevention and treatment of diabetes and its complications. In this study, we summarized the progress in the research of hypoglycemic effect of dammarane saponins in ginseng, American ginseng, notoginseng, and gynostemma pentaphyllum, providing theoretical foundation for further researching.
RESUMO
Objective: Panax notoginseng is an important medicinal plant and its secondary metabolites, P. notoginseng saponins (PNS), synthesized by the mevalonate pathway are the active ingredients. The study on the gene of the key enzyme 3-hydroxy-3- methylglutaryl-coenzyme-A reductases (HMGR) in the mevalonate pathway is helpful for the regulation of PNS syntheses. Methods: The primers were designed according to P. ginseng HMGR (accession number: GU565097.1) from NCBI. Total RNA was extracted from the callus of P. notoginseng. The fragment of HMGR gene was amplified by reverse transcription PCR technology and analyzed. Results: Sequence analysis showed that the cDNA sequence of obtained fragment (PnHMGR) was 1 893 bp, containing an ORF spaning 1 725 bp, and exhibited 98%, 93%, and 80% sequence identity with HMGR in P. ginseng, Eleutherococcus senticosus, and Eucommia ulmoides. The cDNA was a new one as searching in the Genbank. The bioinformatic analysis showed that PnHMGR-encoding protein contained two transmembrane regions and the HMGR catalytic domain, without signal peptide. The expression level of PnHMGR was the highest when the callus of P. notoginseng has grown for 30 d. Conclusion: It is the first time to report HMGR gene isolated from P. notoginseng. The results will provide a groundwork for exploring the molecular function of PnHMGR involved in PNS biosynthesis based on the synthetic biology of P. notoginseng.