Characterization of the Genetic Diversity Present in a Diverse Sesame Landrace Collection Based on Phenotypic Traits and EST-SSR Markers Coupled With an HRM Analysis.

A selection of sesame (Sesamum indicum L.) landraces of different eco-geographical origin and breeding history have been characterized using 28 qualitative morpho-physiological descriptors and seven expressed sequence tag-simple sequence repeat (EST-SSR) markers coupled with a high-resolution melting (HRM) analysis. The most variable qualitative traits that could efficiently discriminate landraces, as revealed by the correlation analyses, were the plant growth type and position of the branches, leaf blade width, stem pubescence, flowering initiation, capsule traits and seed coat texture. The agglomerative hierarchical clustering analysis based on a dissimilarity matrix highlighted three main groups among the sesame landraces. An EST-SSR marker analysis revealed an average polymorphism information content (PIC) value of 0.82, which indicated that the selected markers were highly polymorphic. A principal coordinate analysis and dendrogram reconstruction based on the molecular data classified the sesame genotypes into four major clades. Both the morpho-physiological and molecular analyses showed that landraces from the same geographical origin were not always grouped in the same cluster, forming heterotic groups; however, clustering patterns were observed for the Greek landraces. The selective breeding of such traits could be employed to unlock the bottleneck of local phenotypic diversity and create new cultivars with desirable traits.

Detection and quantification of cashew in commercial tea products using High Resolution Melting (HRM) analysis.

Tea, a popular aromatic infusion and food supplement, prepared from Camellia sinensis (L.) Kuntze leaves, is often subjected to adulteration with various undeclared inorganic and plant-derived materials. Cashew (Anacardium occidentale L.) nut husk is one of the most common plant tea adulterants. To date, there are limited DNA-based technologies for tea authentication and quantitative detection of adulterants. Herein, we used a universal plant DNA barcoding marker coupled with High Resolution Melting (Bar-HRM) analysis to authenticate tea products from cashew ground nut. Additionally, cashew-specific markers coupled with HRM technology were used to detect and quantify adulteration of tea with cashew DNA. This methodology can reliably detect admixtures as low as 1% v/v cashew in commercial tea products. Overall, our results demonstrate that the HRM technology is a strong molecular approach in tea authentication, capable of detecting very low adulterations in DNA admixtures. PRACTICAL APPLICATION: In this study, we established the use of high-resolution DNA-based technologies for the detection of cashew adulteration in tea, even in very low quantities. The technology could be applied to a greater range of plant-based tea adulterants. This work is expected to facilitate the traceability and authenticity of tea products and form the basis for the development of strategies against fraudulent practices.