The effects of polyamine supplement on modifying cold stress in Stevia rebaudiana from molecular and phytochemical viewpoints

In this study, the role of polyamide supplementation in modifying the effects of cold stress in stevia was evaluated from different phytochemical and molecular aspects. In this regard, Stevia plants were first treated with 48 and 96 hours at 4◦C as individual form and then with polyamide supplementation. Then, steviol glucosides content and other secondary metabolites of the plant under different conditions of treatment were evaluated using HPLC technique and ultraviolet spectroscopy, respectively. In the next step, the electrophoretic pattern of stevia plant proteins and expression of a glycosyltransferase, 74G1, were determined by SDS-PAGE and real-time PCR techniques, respectively. The results showed that the content of total flavonoid, total tannin and total phenol in the stevia plants treated with cold and polyamine supplement was higher than that of the cold only treated plants. Results also showed that the rebaudioside A, a steviol glucoside, significantly increased to 25-100 % in the plant treatment with some periods of cold combined with polyamine compared with cold only treatment at p≤ 0.05. The electrophoretic pattern of stevia proteins also indicated that there were some additional bands in coldtreated groups. This band was intensified in polyaminecold treated groups. The expression of the glycosyltransferase gene, 74G1, a key gene in steviol glycosylation biosynthesis pathway, increased 40% in the cold-polyamine treatment group compared with the control.

کلیدواژه ها:

Stevia rebaudiana ، Polyamine ، Cold stress ، Steviol glucosides