Preliminary Study On RNA Interference Of Strawberry DHAR Gene

Ascorbic acid not only provides the minority animals (including humans) who cannot synthesis AsA normally with the source of vitamin C, but also plays a vital role in anti-oxidation, photosynthesis , growth and metabolism of plant, etc. As a result,the content of AsA has become an important indicator to measure the quality of agricultural products. Dehydroascorbate ascorbic acid (DHA) was reduced to AsA with the catalysis of ascorbic acid reductase , which has played a important role in taking advantage of AsA repeatedly and protecting cells components against oxidative damage. Strawberry has high nutritional value and rich vitamin C. In this study, therefore, with the construction RNAi plant expression vector of strawberry DHAR genes, the regulation of this metabolic enzyme genes in the process of AsA accumulation was studied and tested, which can offer theoretical basis about future breeding of high AsA.1. The content of vitamin C from different maturity period fruit and Sen Gala dehydroascorbate reductase activity were measured in this study ,the results show:The content of vitamin C of the same species from green ripe to full red stage increases gradually and the diffrence between full red and red ripe stage is most obvious. The activity of "Sengana" dehydroascorbate ascorbic acid reductase also increases gradually and it has high activity in the late growth stage, which shows AsA accumulation maybe mainly happens in this stage. The results of DPS software analysis show: DHAR enzyme activity and the content of vitamin C is positively correlated with correlation coefficient 0.878, significant at 0.05 level. Which initially identifies strawberry DHAR activity has a certain positive correlation with the content of vitamin C.2. The Optimization of strawberry regeneration systemThe study includes:How different hormone combinations influence the differentiation of shoots, how dark culture influence the inductive rate of shoots of leaves, Etc. The study shows: the most appropriate inductive medium of Sengana leaves is MS +3.0mg/L 6-BA + 0.2 mg/L2,4-D,on which the inductive rate can reach to 73.3%,the average budding number can be 2.2.The inductive rate is highest when the shoots are cultured in light after 7days in dark.3. The Optimization of Agrobacterium-mediated genetic transformation systemThe leaves of Sen Gala Aseptic seedlings were used as the material to establish the optimal genetic transformation system. The study shows: explants differentiation rate can reach to 47.3% with 300mg / L Cef sterilization, the most proper Km selection pressure of Sen Gala is 20mg / L in the bud differentiation stage. 4. To further study the role of DHAR, we are taking a step forward:We obtain the partial cDNA of Dehydroascorbate gene DHAR from strawberry with RT-PCR and construct the plant expression vecter Part27- iDHAR of Dehydroascorbate gene. We obtian 7 RNAi plants which have been tested positive through PCR detection after the RNAi plant expression vecter was transformed into the strawberry cultivars Sengana by the means of Agrobacterium-mediated.