Studies On The Factors Associated With The 1-deoxynojirimycin (DNJ) Content In Tissue Culture Mulberry Seedling

1-deoxynojirimycin (DNJ) and its ramifications are effectiveα- glucosidase inhibitors, and have comprehensive function of pharmacology. They are used in curing diabetes, fatness and virus infections. DNJ has been found in many kinds of plants and microbes. Compared with other plants the content of DNJ in mlberry leaves is higher. Though, there are many reports about the pharmacology function and detecting methods of DNJ, litter is known about the mechanisms for DNJ synthesis. In this study some factors associated with the contents of DNJ were investigated to provide a better understanding for the produce of DNJ by tissue or cell culture and the synthesis mechanisms of it . The main research findings are as follows.1 The DNJ content in tissue culture mulberry seedlings was detected by using RP-HPLC method. The results showed that the DNJ content was not only influenced by mulberry varieties and tissues, but also effected by culture time and conditions etc. Among the 5 mulberry varieties, Nongsang 14 contained most DNJ production (0.1302%)and Xinsang 13 contained least DNJ (0.0701%). The leaves of all the tissue cluture mulberry seedlings showed higher DNJ content than buds and roots. The favorable culture time for the synthesize and accumulate of DNJ was 25 days. The optimal medium for the DNJ synthesis was MS-medium. When N6-medium was used, the DNJ content in tissue culture mulberry leaves was least . The optimal medium pH value was 5.8-6.0. Darkness treatments was benefit for the DNJ synthesis and the optimal darkness treatment time for DNJ synthesis was 5 days.2 The effect of the medium compositions on the DNJ content of tissue culture mulberry seedling leaves was investigated. The results showed that adding fructose was good to the DNJ synthesis and accumulation, and the optimal fructose concertration was 40 g/L. NO3--N could enhance the DNJ content in tissue culture mulberry leaves, adversely, NH4+-N had a negative influence on the synthesis and accumulate of DNJ. When the MS-medium supplemented with 0.5 mmol/L phosphate and 8.175 g/L inorganic ions, the content of DNJ was highest. The existence of aicotinic acid and VB6 in the medium was not good to the synthesis of the DNJ. Metal ions had significant impact on the DNJ content. Proper Fe2+ and Ca2+ in the medium were propitious to the DNJ synthesis. When Fe2+ and Ca2+ concertration were 0.05 mmol/L and 1.5 mmol/L, respectively, the DNJ content was highest. The Mg2+ ions in the medium had a negative influence on the synthesis and accumulate of DNJ.3 The effect of plant hormone on the DNJ content was studied. The results showed that NAA enhanced the DNJ content in tissue culture mulberry leaves. When NAA concent was 0.1 mg/L, DNJ content was the highest. 2,4-D in the medium had a negative influence on the DNJ synthesis. Cytokinins KT and 6-BA were favor for the DNJ synthesis. The best result was obtained when the MS-medium supplemented with is 0.5 mg/L 6-BA, 0.1 mg/L NAA and 1.0 mg/L KT.4 The DNJ contents in the Da 10 tissue cultures of different develop phases, including suspension cells, induced callus from suspension cells, green callus, loose callus, induced callus from stem and root, regeneration buds, leaves, root and plant, aseptic plant were detected. Interestingly, DNJ was only found in regeneration buds, leaves and seedling, aseptic plant, indicating that DNJ was synthesized begining with mulberry buds phase.