Chromosomal evolution in Korean Ajuga species (Lamiaceae)
Bokyung ChoiP1, Hanna Weiss-Schneeweiss2, Tae-Soo Jang1*
1Department of Biological Science, College of Bioscience and Biotechnology, Chungnam National University, Daejeon 34134, Korea; 1Department of Botany and Biodiversity Research, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
Cytological plasticity, which includes chromosomal rearrangements and chromosomal number changes, plays a crucial role in diversification and eventually in speciation in plants. Molecular cytogenetic mapping of rDNA loci (5S, 35S) employing fluorescence in situ hybridization (FISH) has been proved to be useful for identifying direction of chromosomal evolution, and it may reveal taxon specific patterns of the rDNA loci. Molecular cytological approach using FISH can contribute towards understanding of chromosome and genome evolution of Ajuga taxa. The genus Ajuga are herbs and distributed in temperate Eurasian regions. In Korea, four species (A. decumbens, A. multiflora, A. nipponensis, A. spectabilis) are currently recognized. In this study, chromosome mapping of rDNA (5S, 35S) loci were carried out in Korean Ajuga species. All examined species had one to two 5S rDNA sites located either interstitially or subterminally. The 35S rDNA sites were more variable among taxa with two signals found in A. spectabilis while 12 signals were found in A. nipponensis. This study is the first comparative molecular cytogenetic analyses of Korean Ajuga species to better understand the chromosomal evolution in Ajuga.