Karyotype of nine endemic species from alpine subnival belt in the Hengduan Mountains, SW China

The Hengduan Mountain region is one of the biodiversity hotspots of the world. We aimed to examine the karyotypes of nine seed plants from the alpine subnival belt of this region in the present study. By using the plant root tip cytology research method, the results showed that karyotype formulae and karyotype asymmetry were: Eriophyton wallichii with 2n = 2x = 16 = 4m + 12sm, 2B; Marmoritis complanatum with 2n = 2x = 18 = 10m + 8sm, 4A; Lamiophlomis rotata with 2n = 2x = 22 = 12m + 10sm (2SAT), 3A; Codonopsis buUeyana with 2n = 2x = 16 = 8m + 8sm (2SAT), 3A; Pedicularis elwesii with 2n = 2x = 16 = 2m + 14sm (2SAT), 3A; P. rupicola with 2n = 2x = 16 = 4m + 12sm (2SAT), 2A; the two populations of Rheum nobile as follows 2n = 2x = 22 = 18m (2SAT) + 4sm, 3A and 2n = 2x = 22 = 16m (2SAT) + 6sm, 4A; Senecio muliensis with 2n = 4x = 40 = 32m (2SAT) + 8sm, 3A; Soroseris hookeriana with 2n = 4x = 32 = 22m (4SAT) + 10sm, 4A. The chromosome numbers and karyotype of Eriophyton wallichii, Marmoritis complanatum, Codonopsis bulleyana, Pedicularis elwesii, P. rupicola, Senecio muliensis were reported for the first time. Except for Senecio muliensis and Soroseris hookeriana, all of the sampled endemic species were diploid, and showed that polyploidy may not play an important role in the way of adapted extreme alpine subnival belt environment of these plants from the Hengduan Mountains.