Genetic Variation of Shallot (Allium cepa L. Aggregatum Group) in Vietnam

Abstract

To evaluate Vietnamese shallot strains as genetic resources, genetic variation among those collected from three main (northern, central and southern) regions in Vietnam was studied, based on morphology, physiology, and polymorphisms of nuclear, chloroplast, and mitochondrial DNAs. Strains from the northern region had spreading and dark green leaves, bolted late, and formed bulbs early. The bulb skin was white during bulb formation but turned brown after harvest. By contrast, strains from the central and southern regions, that had semi-spreading leaves, bolted early and formed bulbs late. The leaves were yellow green when young, but turned dark green as they matured. The bulb skin was pink when the bulbs were young but became red after harvest. In the dendrogram based on RAPD analysis of total DNA, two groups of strains were formed. One included the strains from the northern region and the other the strains from the central and southern regions. PCR-RFLP analyses of chloroplast and mitochondrial DNAs showed no variation among the strains from the three regions. From the results, two different types of shallot were identified, namely the North type (distributed in the northern region) and the South type (in the central and southern regions). Different characteristics of these two types will be useful for future breeding of shallot, common onion, and wakegi onion in tropical and sub-tropical countries.