Cadmium Chloride and Silver Nitrate Affect the Gene Expression, Stevioside, and Rebaudioside: A Production in Stevia rebaudiana (Bert.)
Department of Biotechnology, 1Department of Plant Breeding, Faculty of Agriculture and natural Resources, Imam Khomeini International University, Qazvin 34149 16818, Iran
G. A. Garoosi, Department of Biotechnology, Faculty of Agriculture and natural Resources, Imam Khomeini International University, Qazvin 34149 16818, Iran, E-mail: firstname.lastname@example.org
Stevia rebaudiana (Bert.) produces steviol glycoside sweeteners that are sweeter than sucrose. Stevioside and rebaudioside A are important steviol glycosides used in food production. This study was conducted to investigate the effect of different concentrations of cadmium chloride (0, 20, 40, 60 and 80 mg/L) and silver nitrate (0, 15, 30, 45 and 60 mg/L) and different sampling times on stevioside and rebaudioside A production and Ent-kaurenoic acid 13-hydroxylase, uridine diphosphate-glycosyltransferase 74G1 and uridine diphosphate-glycosyltransferase 76G1 genes expression in in vitro conditions. The results showed that the application of cadmium nitrate and silver nitrate decreased stevioside and rebaudioside A production. Among various concentrations of cadmium chloride, the highest concentrations of stevioside and rebaudioside A were respectively 39.76 mg/g and 2.27 mg/L dry weight 96 and 72 h after elicitation with 20 mg/L cadmium chloride. Among different concentrations of silver nitrate, the highest amounts of stevioside and rebaudioside A were respectively 33.33 mg/g dry weight was 2.19 mg/L obtained at control condition after 96 h and elicitation with 60 mg/L for 24 h. In elicitation with cadmium chloride the expression all three genes were increased but silver nitrate elicitation increased uridine diphosphate-glycosyltransferase 76G1 gene expression and decreased the Ent-kaurenoic acid 13-hydroxylase and uridine diphosphateglycosyltransferase 74G1 genes expression. The correlation analysis showed that Ent-kaurenoic acid 13-hydroxylase gene expression was not correlated with uridine diphosphate-glycosyltransferase 74G1 and uridine diphosphate-glycosyltransferase 76G1 genes expression, while uridine diphosphateglycosyltransferase 74G1 was inversely correlated with uridine diphosphate-glycosyltransferase 76G1. Also, positive correlations were observed between uridine diphosphate-glycosyltransferase 74G1 gene expression with stevioside synthesis and uridine diphosphate-glycosyltransferase 76G1 gene expression with rebaudioside A.