Abstract
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.
Highlights
Sesame (Sesamum indicum L.) is an ancient oilseed crop of the Pedaliaceae family and its seeds are considered a commodity of great commercial importance
To assess the phenotypic diversity of the 37 sesame cultivars, we used 28 qualitative morphological and agronomical characteristics related to growth, branching, leaf and stem morphology, flower, capsule and seed traits as well as flowering time and seed maturity based on the guidelines of the International Union for the Protection of New Varieties of Plants for Sesamum indicum L. [47] (https://www.upov.int/edocs/tgdocs/en/tg292.pdf)
An accurate knowledge of phenotypic and genetic diversity is key to the effective use and preservation of traditional varieties, which are at a high risk of extinction
Summary
Sesame (Sesamum indicum L.) is an ancient oilseed crop of the Pedaliaceae family and its seeds are considered a commodity of great commercial importance. In the last decade sesame has been classified second after tea and above coffee as well as ninth among the major oil crops as per the annual import quantity worldwide [1]. Sesame is cultivated in more than 11.28 million hectares per world crop harvested area with an annual production of approximately 5.86 million tons from 2015–2019 [1]. It is mainly cultivated in the tropical and semi-tropical regions of Asia, Africa and South
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