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莱宝迪苷A(rebaudioside,RA)是甜叶菊甜菊醇糖苷中的主要甜味成分,其含量受到生物合成中多个酶基因的影响。本研究以6个甜叶菊品种为材料,利用实时荧光定量RT-PCR测定RA生物合成途径中UGT85C2、UGT91D2m和UGT76G1三个关键酶基因的表达量,并与其RA含量进行相关性分析。结果显示UGT76G1基因相对表达量与RA含量有极显著相关关系(p=0.008),而UGT85C2和UGT91D2m基因表达量与RA含量无相关关系,说明UGT76G1基因的表达对RA合成有着较为重要的影响。研究结果可为利用基因工程手段人为调控甜菊醇糖苷的生物合成,提高RA的含量提供理论依据。
Rebaudioside A (RA) is the major sweet component in stevia steviol glycosides and its content is affected by several enzyme genes involved in biosynthesis. In this study, we detected the expression of three key enzymes UGT85C2, UGT91D2m and UGT76G1 in the RA biosynthetic pathway by real-time fluorescent quantitative RT-PCR using six varieties of stevia as materials, and analyzed the correlation with RA content. The results showed that there was a significant correlation between the relative expression level of UGT76G1 gene and the content of RA (p = 0.008). However, there was no correlation between UGT85C2 and UGT91D2m gene expression and RA content, indicating that the UGT76G1 gene expression has a significant effect on RA synthesis. The results provide a theoretical basis for artificially regulating the biosynthesis of steviol glycosides and increasing the content of RA by means of genetic engineering.