Morphological and molecular characterization of onion (Allium cepa L.) genetic sources

Morphological descriptors and molecular analysis methods are used to characterize onion genetic resources and determine genetic diversity levels. The variations that reveal the variety are mostly onion shape, onion color, onion skin thickness, onion flesh color, onion size, etc. due to features such as In this study, morphological definitions and morphological variation levels of local onion genetic resources collected from different locations of the world according to UPOV (International Union for Conservation of New Plant Varieties) criteria were investigated. and molecular characterization according to the SSR method, it is aimed to reveal the current situation in terms of genetic diversity. In the thesis study, it was first collected from different parts of the world and in the Seed Gene Bank (USDA-ARS- National A gene pool consisting of a total of 52 onion genotypes from the Plant Germplasm System NPGS was established. As a result of the research, it was determined that onion genetic sources showed a high level of phenotypic variation in terms of morphological variation. Cluster and Principal Component Analysis were applied to the obtained data. As a result of cluster analysis in onion genotypes, a dendrogram showing kinship relations was obtained. In addition, as a result of Principal Component Analysis, it was determined that ten principal component axes represented 81.05% of the total variation. As a result of molecular analysis of onion genotypes, a total of 188 polymorphic SSR alleles were obtained from 19 SSR primers. As a result of analyzes with SSR markers in onion genotypes, Unweighted Genotypes were divided into 2 different genetic groups according to the Neighbor-Joining method. Genetic distance values between onion genotypes were found to vary between 0.12 and 0.82. As a result of this study, onion genotypes, whose morphological and molecular characterizations were made, will be evaluated as qualified materials in the hybrid onion variety breeding program in the future.