Population Genomics of Rhododendron micranthum Turcz. in the Republic of Korea Based on Genotyping-by-Sequencing (GBS)

This study evaluated the genetic diversity and population structure of Rhododendron micranthum Turcz., a rare plant with a restricted distribution in the Republic of Korea, using genotyping-by-sequencing (GBS). A total of 121 individuals from 11 populations covering the entire distribution range of the species in the Republic of Korea were analyzed using 3330 single-nucleotide polymorphism (SNP) markers. Genetic diversity analysis revealed a mean expected heterozygosity (He) of 0.266, which was lower than that reported for typical perennial plants and other congeneric taxa. Among the populations, the Jecheon (JC) population exhibited the highest genetic diversity (He = 0.297), whereas the Bonghwa (BH) and Yeongwol (YW) populations showed relatively low genetic diversity. Analysis of molecular variance (AMOVA) indicated that 88% of the total genetic variation occurred within populations, and the level of genetic differentiation among populations was moderate (FST = 0.100). Population genetic structure analyses identified three genetic groups, with clear genetic differentiation between the eastern and western populations, which are separated by the Baekdudaegan range. In particular, the YW population exhibited a distinct genetic composition that differentiated it from the other populations, whereas the Yeongju (YJ) population contained ancestry components representing all three genetic clusters observed across the other populations, suggesting that it may represent a central population in the range expansion of R. micranthum in the Republic of Korea. These results are expected to provide important baseline data for establishing effective conservation strategies for R. micranthum in the Republic of Korea.