Chromosome morphology and karyotyping in rangeland species of Astragalus cyclophyllus

Astragalus cyclophyllus, is a perennial plant of leguminosae family which is very palatable forgrazing animals and valuable for apiculture. In the present study the chromosome characteristics and Karyotype of three accessions of Astragalus cyclophyllus were studied. The analysis of distinct mitotic, metaphasic chromosomes involved seed germination, pretreatment of tissue samples, fixation of cellular and chromosomal structures, hydrolyzation of samples, and chromosome staining. Samples were observed icroscopically for chromosome number and morphology which led to the preparation of Karyotype and ideogram of the accessions. The results of the chromosome count showed that all the A. cyclophyllus accessions were tetraploid with 32 chromosomes. This was in agreement with previous report on other Astragalus species containing 32 chromosomes in a tetraploid state. According to the Karyotypic characteristics and Karyotype classificationsfollowing Stebbins method, Hana and Dare Hoze accessions were classified in 2A class and the Sibak accession was classified in 1A class indicating more Karyotypic symmetry. By examining the chromosome length's variation coefficient parameters, the total form percentage, relative length of the shortest chromosome, intra-chromosomal asymmetry index, inter-chromosomal asymmetry index, and the difference of the relative length range, it was specified that the Hana accession had more inter-chromosome symmetry while the Sibak accession had more inter-chromosome symmetry. It is therefore concluded that accessions of this species contain considerable choromosomal variations.