Genotypic characterization and steviol glycoside quantification in a population of Stevia rebaudiana Bertoni from Paraguay

Abstract

Stevia rebaudiana (Bertoni) Bertoni is a widely grown species in various regions of the world, mainly due to its sweetening properties attributed to steviol glycosides. Despite the fact that Paraguay is the center of origin of S. rebaudiana, genetic characterization of local genotypes has not been studied. Considering that accumulation of steviol glycosides is a complex trait, molecular breeding could be an effective method for its improvement. Therefore, the identification of molecular markers associated with steviol glycoside accumulation is important. The aim of this study was to assess the genetic relationship among eight advanced lines of S. rebaudiana and two varieties selected from local germoplasm and quantify their steviol glycoside content. The stevioside and rebaudioside A content in methanolic extract was determined by high-performance liquid chromatography (HPLC), and the molecular characterization of the ten genotypes of S. rebaudiana was performed using SSR and ISSR markers. A wide range of variability was observed for the metabolites of interest under greenhouse conditions. The variety Eirete presented highest stevioside and rebausiode A content, followed by the variety Katupyry. One of the advanced line presented both metabolite content similar to that of Katupyry. Genotyping of these lines showed two main clusters. Cluster I contained the both varieties and advanced lines with higher stevioside and rebaudioside A content. Our results suggest that S. rebaudiana lines with genetic profile similar to that of cluster I, determined mainly by genotype at the markers SUGMS 35 and ISSR 47, might present higher stevioside and rebaudioside A content.