Cell-wall-degrading enzymes produced in vitro and in vivo by Rhizoctonia solani, the causative fungus of peanut sheath blight.

Rhizoctonia solani causes the disease peanut sheath blight, involving symptoms of maceration and necrosis of infected tissue, mainly caused by cell-wall-degrading enzymes (CWDEs). This study investigated the production of CWDEs including polygalacturonase (PG), polymethyl-galacturonase (PMG), cellulase (Cx) and ß-glucosidase by R. solani in vitro (in liquid culture) and in vivo (in peanut plants). Significant PG, PMG, Cx and ß-glucosidase activities were detected in infected tissues including stalk and leaves of Baisha and Silihong peanut cultivars. Extracts of healthy tissue showed little or no such activities. In shaken liquid cultures of R. solani in medium containing pectin or pectin plus carboxymethyl cellulose (CMC) as the carbon source(s), PG and PMG were notably active. Significant Cx activity was detected in cultures with CMC or pectin plus CMC as the carbon source(s). However, only a very low level of ß-glucosidase activity was observed in cultures with any of the tested carbon sources. An increase of pH was recorded in decayed peanut tissues and liquid culture filtrates; the filtrate pH and fungal growth positively correlated. The fungal growth and/or pH were important factors for the production of PG, PMG and Cx in culture with pectin plus CMC as the carbon source. A single active PG isozyme with isoelectric point around 9.2 was detected in culture filtrates and in infected peanut tissues by the method of isoelectric focusing electrophoresis. The crude enzymes extracted from liquid culture of R. solani induced decay of healthy peanut leaves.

Proteomics research and related functional classification of liquid sclerotial exudates of Sclerotinia ginseng.

Sclerotinia ginseng is a necrotrophic soil pathogen that mainly infects the root and basal stem of ginseng, causing serious commercial losses. Sclerotia, which are important in the fungal life cycle, are hard, asexual, resting structures that can survive in soil for several years. Generally, sclerotium development is accompanied by the exudation of droplets. Here, the yellowish droplets of S. ginseng were first examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the proteome was identified by a combination of different analytical platforms. A total of 59 proteins were identified and classified into six categories: carbohydrate metabolism (39%), oxidation-reduction process (12%), transport and catabolism (5%), amino acid metabolism (3%), other functions (18%), and unknown protein (23%), which exhibited considerable differences in protein composition compared with droplets of S. sclerotium. In the carbohydrate metabolism group, several proteins were associated with sclerotium development, particularly fungal cell wall formation. The pathogenicity and virulence of the identified proteins are also discussed in this report. The findings of this study may improve our understanding of the function of exudate droplets as well as the life cycle and pathogenesis of S. ginseng.

[Influence of exogenous ginsenosides on new forest soil microbial communities].

Ginsenosides are the main active ingredient and allelochemicals of Panax ginseng, and they play an important role in ginseng growth and in ecological adaptation. To study the influence of ginsenosides on soil microbial communities, the method of given exogenous total ginsenosides of different concentrations were used to study the influence of ginsenosides on new forest soil microbial community, evaluate the change of metabolic activity of microbial community and investigate the ecological effect of ginsenosides on soil microbial community. Results showed that, exogenous total ginsenosides promoted metabolic activity of microbial community in new forest soil at different concentrations compared with the control after 10 d and 40 d treatment. After 10 d,except for the Evenness index, all of the other indices indicated that the functional diversity of the soil microbial community in the new forest firstly increased then decreased with increase of the total ginsenosides concentration. The Substrate richness for 0.01 g•L⁻¹ soil treatment was significantly different from that of the control. After 20 d, 30 d and 40 d, except for the Evenness index, all of the other indices indicated that the functional diversity of the soil microbial community in the new forest increased with total ginsenosides. These results suggested that ginsenosids can change soil microbial community and microbial metabolic activity, which alter soil microbial ecology and accordingly affect the growth of ginseng with accumulation of ginsenosides in the soil.

Ampelopsin sodium induces mitochondrial-mediated apoptosis in human lung adenocarcinoma SPC-A-1 cell line.

Ampelopsin is a well-known flavonoid which has variety of biological and pharmacological actions including anticancer effects and induction of apoptosis on the several cancer cell lines. The present study aimed to evaluate the role of ampelopsin sodium (Amp-Na) in the mitochondrial-mediated apoptosis of human lung adenocarcionma SPC-A-1 cells. The analysis of cell proliferation and ultrastructure were performed. Furthermore, to clarify its action mechanism by determining the mitochondrial membrane potential (Δψm), intracellular calcium (Ca2+) concentration, mitochondrial nitric oxide (NO) level and total ATPase activity. The results showed that Amp-Na markedly inhibited the SPC-A-1 cell proliferation and caused ultrastructural apoptosis feature in SPC-A-1 cells in a dose-dependent manner. Amp-Na led to a rapid and sustained Ca2+ elevation and Δψm reduction, and induced the mitochondrial NO production and decreased the total ATPase activity in SPC-A-1 cells. The results enhance the potential of Amp-Na as a therapeutic drug for treating lung cancer, and provide new information for mechanism of Amp-Na which induces mitochondrial-mediated apoptosis in tumor cells.

[Allelopathic effects of phenolic compounds of ginseng root rhizosphere on Cylindrocarpon destructans.] / äººå‚è¿žä½œæ ¹é™ åœŸå£¤ä¸­é šé ¸ç‰©è´¨å¯¹äººå‚é”ˆè ç— èŒçš„åŒ–æ„Ÿæ•ˆåº”.

In this study, five phenolic compounds of ginseng rhizosphere soil were identified by HPLC, including gallic acid, salicylic acid, 3-phenylpropionic acid, benzoic acid and cinnamic acid. The results show that five phenolic compounds inhibited mycelium growth and spore germination at high concentration, but promoted mycelium growth and spore germination at low concentration. Gallic acid, salicylic acid, benzoic acid of 0.5 mmol·L-1 and 3-phenylpropionic acid, cinnamic acid of 0.05 mmol·L-1 could significantly promote the spore germination, mycelium growth and disease severity of Cylindrocarpon destructans.

[The inhibitory effect of anti-streptococcus mutans immunoglobulin of yolk on glucan synthesis of Streptococcus mutans].

OBJECTIVES: To observe the inhibitory effect of anti-Streptococcus mutans Hen-egg-yolk (IgY) on glucan synthesis of Streptococcus mutans. METHODS: Determine the glucan with anthrone method after using the different titer of IgY on S.mutans and S.sobrinus. RESULTS: The inhibitory effect of antibody on S.mutans and S.sobrinus synthesis glucan had a similar tendency. The effect of inhibit glucan synthesis was influenced by the titer of antibody. High titer with high inhibition. Begin with the group of 1:16 titer, the group of 1:2 titer showed the highest inhibition (P<0.05). CONCLUSION: The antibody can reduce synthesis of glucan from S.mutans and S.sobrinus.