Molecular markers development and application in garlic

Garlic (Allium sativum L.) as a clonally propagated crop has a considerable amount of genetic diversity and very large genome which limits genetic and molecular studies in this crop. Molecular markers have been successfully applied for revealing genetic diversity, constructing linkage maps, and developing treat associated markers in garlic. In previous studies, the genetic diversity among garlic clones was mainly determined using isozyme, amplified fragment length polymorphism (AFLP), random amplified polymorphic DNA (RAPD) markers, and simple sequence repeat (SSR) markers. The tree topologies of markers systems were generally concordant but RAPD and isozyme dendrograms reflected less polymorphism. Molecular markers demonstrated that genetic diversity among the garlic clones is high. A DNA marker for significantly associated with the bolting phenotype of garlic was developed from the mitochondrial genome. This marker discriminated bolting garlic clones from non-bolting genotypes efficiently. The genetic map of garlic was also constructed using AFLP markers and gene-specific markers. The map of garlic demonstrated that the garlic genome consists of a high amount of duplications and generated linkage groups can be utilized to map important traits. Garlic has a complex genome, therefore, more co-dominant markers such as single nucleotide polymorphism (SNP) and SSR markers are needed to improve genetic and breeding studies in this crop.