Study On Key Enzymes In The AsA Metabolic Pathway Of Three Strawberry Varieties

Ascorbic acid or vitamin C, is a small molecule antioxidant with high abundance in plant tissue. It plays an important role in scavenging free radicals, regulating of cell growth and division, and resistance to environmental stress. In addition, it is also a necessary micronutrient for maintain healthy of human. AsA content has become an important indicator to measure the quality of agricultural products, and thus be payed close attention. In this study,15 various subtypes member of 5 key enzymes gene family(MDHARs, GRs, AOs, DHARs, APXs), which involved in AsA metabolic pathway were found from three cultivars of Strawberry Fragaria x ananassa cv. Akihime?Fragaria x ananassa cv.'Benihoppe'?Fragaria x ananassa. var. 'Benihoppe' rich in vitamin C.. And the structures and functions of them were predicted by means of bioinformatics. At the same time, the expression patterns of the 15 genes be analyzed in different developmental stages of fruit in strawberry. The following findings were obtained:1. The GenBank has logged in Arabidopsis thaliana, peach, pear, plum, apples, grapes, spinach and other plants MDHARs, GRS, AOS, DHARs, APXs gene sequences were compared, conservative region into forest strawberry homologous genome (http://www.rosaceae.org/) into alignment, AsA GSH cycle way in five related gene family (MDHARs, GRS, AOS DHARs, APXs) 15 different subtypes of members.2. Expression level and the activity of DHAR is higher than MDHAR, es pecially in later stages. Whereas plant leaves had a opposite tendency. Combin ed with the previous research, we speculate, DHAR react in Non-photosynthetic tissues, MDHAR react in photosynthetic tissues. The effects of accumulation o f MDHAR is limited in Non-photosynthetic tissues.3. Strawberry AsA mainly accumulated in the later stage of fruit development, the content of AsA was significantly positively correlated with APX, MDHAR and DHAR enzyme activities. The content of AsA in Fragaria x ananassa cv.'Benihoppe' was significantly negatively correlated with APX enzyme activity, which was significantly positively correlated with MDHAR, DHAR and GR. The content of AsA was significantly positively correlated with the activity of DHAR and GR in'white'. The three materials were significantly positively correlated with DHAR, indicating that DHAR plays an important role in the accumulation of As A in strawberry.4. Fragaria x ananassa cv. 'Benihoppe' which has high content of AsA compared with two other materials, the main difference is that the Fragaria x ananassa cv. 'Benihoppe' of DHAR gene expression has a relatively high amount, but the expression of APX is relatively low, which DHAR1 and APX2, APX3 the most significant difference in relative expression.APX2 was 95% homologous to Rosa roxburghii APX, DHAR1 was 93% homologous to Rosa roxburghii DHAR. The results imply the regulation pattern of the Fragaria x ananassa and Rosa roxburghii has the comparability. Therefore, DHAR1 and APX2, APX3 possible is the key enzyme in strawberry AsA content..