Effects of different technical substitutions on reducing replant disease of Radix pseudostella-riae and the underlying mechanism.

Radix pseudostellariae is a traditional Chinese medicinical herb, with tuberous roots being used as a medicine. Serious continuous monoculture problems were suffered from process of artificial and intensive cultivation. To explore the effective technical methods to overcome the monoculture problems, the effects of different technical substitution patterns on soil environment remediation, photosynthetic physiology and yield performance of R. pseudostellariae were assessed under continuous cropping system with four technical substitution treatments in the phase between two crops after the newly harvested R. pseudostellariae (first crop): fallow (RP-F-RP), fallow treated with microbial fertilizer (RP-F-BF), water flooding (RP-WF), and water flooding treated with specific microbial fertilizer (RP-WF-BF). Results showed that RP-WF-BF pattern was the single one that could effectively restore R. pseudostellariae yield under two-year monoculture and three-year monoculture to more than 90% and 70% of the newly planted respectively. All the other patterns did not significantly improve R. pseudostellariae yield under two-year monoculture. The contents of polysaccharide and total saponin in R. pseudostellariae under RP-WF-BF treatment were significantly increased by 15.3% and 16.5% compared with those of the newly planted, respectively. The abundance of beneficial microorganisms in the rhizosphere soil of R. pseudostellariae significantly increased. A reverse pattern occurred for pathogens under RP-WF-BF pattern. Moreover, soil nitrogen cycling was improved. The expression of AOB, nosZ and nirK was increased by 931%, 124% and 100% compared with those in the RP-F-RP pattern, respectively. Soil acidification under RP-WF-BF pattern was alleviated. The alleviation of soil biological and abiotic stress enhanced the stability of the antioxidant enzyme system, thereby improving the growth and development of R. pseudostellariae at the seedling and the early expand stages. The chlorophyll content, leaf area index and photosynthesis rate of leaves were increased, with the dry matter translocation improved and accumulation of underground dry matter accelerated, which ultimately increased yield and quality under RP-WF-BF pattern. In this study, the separate water flooding treatment (RP-WF) and microbial fertilizer treatment (RP-F-BF) failed to significantly reduce the continuous cropping obstacles of R. pseudostellariae, while the combination of them could produce a multiplication effect of sustainable strengthening on rhizosphere environment. The findings suggested that effective technical substitution could reduce replant disease of R. pseudostellariae.

[Study on quality standard of fried Vaccariae Semen standard decoction].

According to the preparation principle of standard decoction of Chinese herbal medicines, fourteen batches of fried Vaccariae Semen decoction were prepared in this study and the quality research was carried out to establish a quality evaluation method for the standard decoction of fried Vaccariae Semen. The contents of vaccarin were determined, and its transfer rate from decoction piece to standard decoction was calculated. The extract rate and pH value were measured, and HPLC fingerprint method was established for analysis. The results of the 14 batches of samples revealed that the transfer rates of vaccarin were between 58.98%-93.94%; the extract rates were between 8.67%-17.83%, and the pH values were between 5.55-6.44. Moreover, 9 common chromatographic peaks were identified in fingerprints analysis. The similarities of the 14 batches of samples were analyzed and compared, and the results showed that the similarities were all higher than 0.96. In this study, the preparation process for fried Vaccariae Semen standard decoction was standard, with high similarities in fingerprint. A convenient and reliable method of comprehensive quality evaluation was established in this study, with a high precision, stability and repeatability, which can provide a reference for the quality control of fried Vaccariae Semen standard decoction, dispensing granule and related Chinese classical formulas(decoction).

Application of binding spectra in DMIs fungicide screening / 生物工程学报

In order to establish a fast and accurate method for novel DMIs fungicide screening, lanosterol 14alpha-demethylase of Magnaporthe grisea expressed in E. coli was used as target enzyme and the DMI fungicides diniconazole, tebuconazole, triadimenol and triadimefon were used as representative fungicides, the effects of enzyme activity, enzyme purity and concentration on the binding spectra were investigated. The results showed that active enzyme, elimination of interference of other P450s and proper enzyme concentration were necessary for obtaining accurate binding spectra. The Kd values of diniconazole, tebuconazole, triadimenol and triadimefon were 0.143 micromol/L, 0.24 micromol/L, 0.257 micromol/L and 0.307 micromol/L respectively, which significantly correlated to their 120h-EC50 values on the growth of Magnaporthe grisea. The results indicated that the binding spectra of fungicide and lanosterol 14alpha-demethylase can serve as a reliable and fast method for novel fungicide screening.