Karyomorphology of four population of two species of Tanacetum L. from Iran

In the present study, the detailed karyomorphology of four populations belonging to two species of Tanacetum sect. Xylopyrethrum (T. joharchii, T. kotschyi (Zanjan), T. kotschyi (Urmia), T. kotschyi (Marand)) were studied by using aceto orcein staining of meristamtic root tips. The karyomorphology of four populations are reported here for the first time. Ideograms of each population were made and karyotypic characteristics including the chromosome number, total karyotype length (TKL), Intra chromosomal (A1), Interchromosomal (A2) asymmetry indices, Karyotype form percentage (TF %), Relative lenghth (RL), Mean centromeric index (CI), and Arm ratio (AR), Karyotype classification followe, using Stebbins classification. Different populations of T. Kotschyi and T. joharchii were triploid, 2n=3x=27. At mitotic metaphase, all chromosomes had median region (m), submedian (sm) and subtelocentric (st) centromeres. The karyotypes are classified in types 2A, showing the presence of a primitive symmetrical karyotype in the genus Tanacetum. Based on karyotype formula, total form percentage (TF%) and Intra chromosomal index (A1), T. kotschyi, Marand population showed asymmetrical karyotype and advanced while T. kotschyi, Zanjan population had an symmetric karyotype and primitive comared with other populations.