Genome size variation and karyotype diversity in eight taxa of sensu stricto (Rosaceae) from China.

Eight taxa of Linnaeus, 1753 sensu stricto (Rosaceae) from China have been studied karyologically through chromosome counting, chromosomal measurement and karyotype symmetry. Genome size was also estimated by flow cytometry. Six taxa, Cheng ex T.T.Yu et K.C.Kuan, 1963, S. hupehensis var. paucijuga (D.K. Zang et P.C. Huang, 1992) L.T. Lu, 2000, C.K. Schneider, 1906, (Hance, 1875) Hedlund, 1901, Koehne, 1913 and C.K. Schneider, 1906 are diploids with 2n = 34, whereas two taxa, Handel-Mazzetti,1933 and McAllister, 2005 are tetraploid with 2n = 68. In general, the chromosome size is mainly small, and karyotypes are symmetrical with predominance of metacentric chromosomes. Genome size variation of diploids and tetraploids is 1.401 pg -1.676 pg and 2.674 pg -2.684 pg, respectively. Chromosome numbers of and S. hupehensis var. paucijuga, and karyotype and genome size of eight taxa studied are reported for the first time. This study emphasised the reliability of flow cytometry in genome size determination to infer ploidy levels in Chinese native species.