Karyotype Criteria of Some Taxa of Asteraceae (Compositae) from Saudi Arabia.

Abstract

Karyotype Features for 12 taxa of Asteraceae (Compositae) from different geographic areas from Saudi Arabia studied. Karyotyping were carried out to construct a karyogram. Chromosome types were determined. All measurements of chromosome length (MCL) and chromosome arm ratio (i.e. MAR) within the karyotype were estimated. Results revealed that eight taxa were found to have a basic chromosome number of x = 9. On the other hand, numbers of somatic chromosome varied between 2n = 14 in the case of Pulicaria crispa to a tetraploid of 2n = 32 Osteospermum vaillantii. Most of taxa studied have karyotypes of metacentric to submetacentric chromosomes. Polyploidy numbers of chromosomes were recorded only with Osteospermum vaillantii as a tetraploid of 2n = 32 (x = 8). Launaea capitata had the longest chromosomes (MCL=6.27±0.33 μm), whereas Anvillea garcinii had the shortest chromosomes (MCL 2.21+0.24 μm). All patterns of the studied karyotypes were found to be symmetric with total form percent (TF%) above 40 except Pluchea dioscoridis had a TF% of 39.12. The highest value of TF% (47.03) was found in Anvillea garcinii. Conclusively, the values of TF%, calculated MAR, intra-chromosomal asymmetry index (A1and inter-chromosomal asymmetry index A2) for the studied species are supportive to the assumption that the karyotype in the family were symmetrical.