A cytogenetic study was conducted on Rheum tanguticum populations from Huangnan Tibetan Autonomous Prefecture, China. The results revealed the chromosome numbers 2n=22 and the karyotype formulae are 2n=22=22m or 2n=22=2sm+20m, belonging to Stebbins 1A type. However, it was interesting to observe metaphases with variable B chromosomes (1, 2, 3, 4, 6, 7) in a few specimens. For the fi rst time, the occurrence of B chromosomes was reported in natural populations of R. tanguticum. The number of B chromosomes in R. tanguticum varied not only among individuals but also within the same root tip.
Fig. Cytological features of R. tanguticum. A-B, Chromosomes of metaphases.
Aʹ–Bʹ, Karyotypes. A, Aʹ, MX population. B, Bʹ, NX population. Bars=10μm.
1. Author Information:Hu Yanping, Li Wang And Yi Li*
Correspondence: E-mail address: liyi@nwipb.cas.cn
2. Published : Caryologia Vol. 64, no. 3: 320-324, 2011.