Chromosome Study in Five Endemic Kniphofia Species (Asphodelaceae) of Ethiopia

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Addis Ababa University


The karyotype of five endemic Kniphofia species of Ethiopia were studied. The studied species are: K. foliosa, K. schimperi, K. hildebrandtii, K. isoetifolia, and K. insignis. Somatic chromosomes were prepared from the root tip meristem using colchicines, 8-hydroxyquinoline or ice-cold pretreatment, followed by fixation (3:1, ethanol:acetic acid) and then enzyme maceration in pectinase-cellulase solution at 37°C for about 1 hr. Air-dry slides were prepared and stained in Giemsa stain in Sorensons phosphate buffer (pH = 6.8). The karyotype analysis has shown that K. foliosa, K. schimperi, K. hildebrandtii and K. isoetifolia are diploid with 2n = 12, where as K. insignis has 2n = 22 chromosomes which is assumed to be a polyploid on the basis of x = 6 for the genus. Polyploidy is the first report for the species. Morphologically, the chromosomes showed a gradual decrease in size in all the species with only small differences between the longest and the shortest chromosomes of each species. The size differences are relatively more pronounced in K. insignis. The karyotype formula was found to be 2m + 8sm+ 2st in K. foliosa, K. schimperi and K. hildebrandtii; 2m + 2m/sm + 8sm for K. isoetifolia and 4m + 12sm + 1sm/st + 5st for K. insignis. Generally, there is only a minor degree of differentiation observed among the karyotypes of the diploid species. One pair of small satellites were observed on the tip of short arms in K. foliosa and K. hildebrandtii, two pairs in K. schimperii and K. isoetifolia and in K. insignis, the secondary constriction is located in the middle of the long arm of a pair of chromosomes and thus delineated two large satellites. Kniphofia foliosa from ‘Laga Shore’, about 10 kms from Gedo town, west of Addis Ababa, was found to have a B-chromosome. This is the first report of B-chromosome for the species as well as the genus. In spite of the fact that samples were collected from only a limited number of sites, the cytogenetical information reported here would create only the basis for further cytological investigation of Kniphofia species. It is, thus, recommended that further cytological and molecular studies including specimens from a wider geographic area should be carried out. Key words: B-chromosome, Chromosome, Endemic Kniphofia species, Ethiopia, Karyotype, Polyploidy.



B-chromosome, Chromosome, Endemic Kniphofia species, Ethiopia, Karyotype, Polyploidy