STUDIES ON INTRASPECIFIC DIFFERENTIATION IN TROPICAL ONION (SHALLOT) AND ITS RELATIVES

Grouping of the 228 accessions of shallot or wakegi collected from Asian countries based on morphological and flowering traits was conducted. Almost of all the collected accessions were classified into shallot or wakegi. Discrimination of shallot from wakegi by isozyme analysis clarified that all the accessions from Japan, Korea and Taiwan were wakegi, those from Thailand, Malaysia and Bangladesh were shallot, and those from Indonesia were mixture of shallot and wakegi. Particularly, the genetic diversity in shallot and wakegi was distinct in West Java and South Sumatra, Indonesia. It is suggested that one of the places of origin of wakegi may be thought to be this area. RAPD analysis also clarified the genetic diversity of the crops in this area. Chloroplast DNA analysis clarified that most of wakegi accessions were the hybrid of Welsh onion * shallot, but that there are a few accessions derived from shallot as maternal and Welsh onion as paternal parents. Major anthocyanins in the accessions were cyanidin and only quercetin was found as flavonol. The ratio of the flavonol to anthocyanins was different in shallot and wakegi, and the stableness of color appearance under UV lights was different by accessions. There were also diversity in response to daylength and temperature for bulb formation and in depth of bulb domancy. These physiological traits were highly related to the classification by isozyme and DNA analyzes.