Biocontrol mechanism of Myxococcus fulvus B25-I-3 against Phytophthora infestans and its control efficiency on potato late blight.

Phytophthora infestans is the pathogen of potato late blight, which is one of the most serious diseases of the potato. Myxobacteria, especially Myxococcus, become a valuable biological control resource due to their preponderant abilities to produce various secondary metabolites with novel structure and remarkable biological activity. In a previous study, Myxococcus fulvus B25-I-3 with antagonistic activity against P. infestans was isolated from an environmental sample by rabbit fecal induction method. The biocontrol mechanism of M. fulvus B25-I-3 against P. infestans and its control efficiency on potato late blight were studied. The results showed that the active substances produced by strain B25-I-3 had strong inhibitory effect on the asexual reproduction and sexual reproduction of P. infestans. In addition, the active substances could reduce the content of soluble proteins and the activity of the protective enzymes (polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, superoxide dismutase) in P. infestans and increase the oxidative damage and permeability of cell membrane. And the active substances could inhibit the infection of the detached potato leaves by P. infestans significantly. In conclusion, M. fulvus B25-I-3 can produce active substances against P. infestans and has potential value to develop into biological pesticides for the control of potato late blight. The completion of this work may provide basic data for the isolation and identification of active substances and the development of pesticides against potato late blight.

[Evaluation of Amberlite XAD-1600 resin-based purification of the bioactive components from Radix Paeoniae Alba and Rhizoma Curcumae Longae extracts by pharmacodynamic and toxicological models].

OBJECTIVE: To evaluate the pharmacodynamics and toxicicity of the major bioactive components extracted and purified from Radix Paeoniae Alba and Rhizoma Curcumae Longae using Amberlite XAD-1600 resin. METHODS: Amberlite XAD-1600 was used to purify the bioactive components from the crude 75% ethanol extracts of the two herbs. The pharmacodynamic and toxic effects of the crude extracts and extract purified using XAD-1600 resin were comparatively examined with two acute inflammatory models, two pain models and acute toxicity test in vivo. RESULTS: The anti-inflammatory and analgesic effects of the purified extract were significant stronger with lower toxicity than those of the crude ethanol extract. CONCLUSION: Amberlite XAD-1600 resin allows efficient extraction and purification of the bioactive components from the two herbs.