Karyotype analysis of Rheum palmatum

Rheum palmatum, one of the source plants of the traditional Chinese medicine rhubarb, is anendemic and endangered species. To our knowledge, this is the first report on the chromosome number and karyotype of this species. Sectioning combined with micrography was used to analyze the karyotype. The following results were obtained: R. palmatum had a stable chromosome number 2n = 22; the basic number of chromosomes was 11; karyotype formula is 2n = 22 = 20 metacentric + 2 submetacentric, belonging to Stebbins' 1A type; and karyotype asymmetry index was 55.39%. The present study showed that R. palmatum has a primitive type of karyotype.