Karyotype studies on Lycoris radiata populations from China

Lycoris radiata is an important medicinal and ornamental plant of China. In the present study, somatic chromosome counts and karyotype analyses, which are important aspects of plant phylogeny and evolution, were performed in 466 individuals from 25 L. radiata populations by root tip squash method. Chromosome counts revealed that 10 populations were diploid (2n = 2x = 22) and 15 were triploid (2n = 3x = 33). Except for one diploid population containing some triploid plants, the remaining 24 populations showed a single cytotype. Karyotype analysis showed that the karyotypes of L. radiata varied in different populations and even within the same population. However, based on the Stebbins' system, the karyotype of all the populations could be classified in 4A classes. The cluster analysis and ordination methods demonstrated that the L. radiata populations grouped in two major clusters. Previous research has shown that the triploid strain of L. radiata is a genetically identical species. However, the cluster analysis revealed that the triploid strains clustered in two groups instead of one, which indicates that these strains may not be identical species, genetically. This study is expected to improve the understanding of the genetic diversity in L. radiata and provide a basis for future studies on species differentiation, speciation, and taxonomy.