ORIGIN OF WILD RHODODENDRON TRANSIENS AND ITS CULTIVARS BY MICROSATELLITE ANALYSIS
Rhododendron transiens Nakai classified as subsection Tsutsusi is designated as one of native azalea species in Japan, although its taxonomic position is still uncertain. It had been found in suburban forests in Kanto region and many cultivars were produced since Edo era (1603-1867). Recently, its wild population is critically endangered. In a previous study using leaf morphology and isozyme, it was suggested that cultivars of R. transiens were related to the species which are classified as subsection Scabra. But further investigation using wild individuals and molecular analysis has not yet been conducted. To reveal the origin of wild R. transiens and its cultivars, microsatellite analysis was performed using six nuclear microsatellite loci. To assess genetic relationship among wild R. transiens and its cultivars together with their close-related species, R. kaempferi Planch in the same subsection, and R. macrosepalum Maxim, R. ripense Makino, R. scabrum G. Don, R. amanoi Ohwi, and their cultivars which are classified as subsection Scabra, we performed structure analysis. According to the results of structure analysis, ΔK statistics supported K=2 (number of clusters) as being the most likely subdivision. R. transiens and its cultivars were assigned into same clusters of R. ripense and Ryukyu azaleas (R. ripense putative hybrids). Phylogenetic tree of cluster analysis also supported this relationship. These results suggested that R. ripense or Ryukyu azalea might be related to the origin of R. transiens.
Miyano, M., Nakayama, A., Handa, T. and Kurashige, Y. (2013). ORIGIN OF WILD RHODODENDRON TRANSIENS AND ITS CULTIVARS BY MICROSATELLITE ANALYSIS. Acta Hortic. 990, 229-233
endangered species, SSR, genetic structure, hybrids