Cytogenetical Study of Cynanchum wilfordii and Cynanchum auriculatum using Fluorescence In Situ Hybridization (FISH)

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/ by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Dried tuberous roots of Cynanchum wilfordii are known to relieve menopause symptoms. However, the dried roots of C. wilfordii are morphologically similar to those of C. auriculatum, which makes it difficult to distinguish when used as a medicine. Various comparative studies have focused on chemical or molecular analysis of these roots. However, the differences between the two species at the cytogenetic level based on chromosome structure and composition remain to be elucidated. Methods and Results: For chromosome slides, the roots were fixed in 8-hydroxyquinoline, digested with enzyme mixture, and spread on slides. 5S and 45S rDNA were used as cytogenetic markers for the analysis of nuclear genomes by FISH. The chromosome number of the two species was 2n = 22, with a relatively short length, 1.13 μm 4.24 μm and 1.00 μm 3.42 μm with respect to each other. Both species represent one pair of 5S and 45S rDNA signal on chromosome 1, at the proximal region and peri-centromeric region, respectively. Conclusions: These preliminary cytogenetic data using FISH in C. wilfordii and C. auriculatum could be valuable for the comprehension of Cynanchum genome history.