Bulb onion (Allium cepa L.) has a very large genome composed of a high proportion of repetitive DNAs. Genetic analyses of repetitive sequences may reveal microsatellites in order to increase the number of genetic markers in onion. Thirty microsatellites were previously isolated from an onion genomic library (Fischer and Bachmann, 2000). A complete set of Japanese bunching onion (A. fistulosum) – shallot (A. cepa Aggregatum group) monosomic addition lines were used to assign these microsatellites to the chromosomes of A. cepa. Simplified PCR conditions for each microsatellite were determined and 28 of the 30 primer pairs amplified DNA fragments, of which 21 microsatellite markers were assigned to chromosomes of A. cepa. Subsequent mapping of these microsatellites will enable us to establish the chromosomal distribution of these markers.
The potential of microsatellite markers for use in genetic studies has 1 been evaluated in Allium cultivated species (Allium cepa, A. fistulosum) and its allied 2 species (A. altaicum, A. galanthum, A. oscaninii, A. roylei, A. vavilovii shallot and bulbonion but also for applying to segregation analyses in its F 2 population.
Polymorphic analyses of simple sequence repeat regions on chloroplast genomes in 34 vegetables were conducted using a set of consensus SSR primer pairs. A sufficient number of DNA markers were obtained in this study and could be available for polymorphic analyses at the species level. The most successful result was obtained from the polymorphic analyses of cultivated and wild species in Allium. The DNA fingerprints of Allium facilitated the identification of each species except in one difficult case. The fingerprint of a natural hybrid, A. × wakegi, could not be distinguished from that of its estimated seed parent, A. fistulosum. The DNA markers obtained from this study seem to have potential not only for breeding purposes but also for cultivar identification in various species of vegetables.