Studies On The Cumulative Change Patterns Of Stilbenes In Morus Alba L.

Stilbenes are a group of materials that have the benzene diene nucleus or the polymers, including resveratrol, oxyresveratrol and mulberroside A, which can be obtained from mulberry. Stilbenes have been widely studied in plant physiology, pharmacology and human health for their important value in the research and development. But stilbenes are secondary metabolites in plant; with low content and unstable nature, they are easily lost in the process of extraction and purification. This resulted in the difficulty to produce them in a large scale and hence impaired their application, and also led to a relatively high price. Tough Mulberry resources are rich in our country; the study on stilbenes in mulberry was rare. This study aimed to investigate the composition of major stilbenes in different portions of different mulberry varieties collected in different seasons. The expression patterns of STS, CHS and the content of stilbenes, flavonoids in mulberry seedlings treated with UV light were studied. The results were as follows:1. A simple, sensitive and specific HPLC method was developed for simultaneous determination of the three major active constituents in mulberries, namely mulberroside A, oxyresveratrol, resveratrol, which were completely separated within21min, and were stable in12h, suggesting that the method can be used to analyze the three major stilbenes in mulberry.2. The main contents of stilbenes varied according to different portions of different mulberry varieties collected in different seasons. It was found that mulberry varieties, Hongpihusang, Zhongshenghuosang, Heilusang, Tang10, Xiaojiguansang have high content of stilbenes; Among different positions of mulberry, the root, bark and periderm vestige have higher level of stilbenes; the same is true for autumn, winter and spring.3. By correlation and regression analysis of the contents of stilbenes in different parts and axial root bark, we found that the contents of mulberroside A, oxyresveratrol, resveratrol in different parts and axial root bark were positively correlated. 4. The content of H2O2in mulberry seedlings treated with UV light was significantly higher than that in the control. The body defense systems response to stress by increasing the stilbenes and the total antioxidant capacity. The GSH reduces H2O2and clear away free oxygen from the body, maintaining in plants a balanced and dynamic state between the production and elimination of activated oxygen.5. The expression pattern of STS, CHS and the content of stilbenes, flavonoids in mulberry seedlings treated with UV light were studied. It was observed that the UV light induces STS, CHS expression and the accumulation of stilbenes and flavonoids in mulberry seedlings. The expression pattern of STS, CHS and that of the accumulation of stilbenes, flavonoids were basically similar, implying that stilbenes and flavonoids biosynthesis and accumulation may be regulated by STS and CHS.6. In the current study we also observed that the UV light treatment induces STS and CHS expression in root, stem and leaf of mulberry seedlings. This effect is more prominent in leaf.In conclusion, the main contents of stilbenes varied in different portions of different mulberry varieties collected in different seasons; the results of the correlation and regression analysis indicated that the contents of stilbenes in different parts could predict the content of the axial root bark. The results can be used as a reference to screen mulberry materials with higher level of stilbenes and for breeding and preserving excellent germplasm during the process of system breeding for mulberry rich in stilbenes.It was observed that the UV light treatment promoted STS, CHS expression and the accumulation of stilbenes and flavonoids in mulberry seedlings. It was also observed that UV light treatment promoted STS and CHS expression in root, stem and especially in leaf of mulberry. Our preliminary results demonstrated at the molecular level the regulation mechanism of the STS, CHS expression and the biosynthesis of stilbenes, flavonoids in mulberry seedlings treated with UV light. The results obtained during this research project provide a theoretical and experimental basis for the future study in the regulation of the expression of STS, CHS and the controlling of the biosynthesis of stilbenes, flavonoid by genetic engineering method.