Somatic Chromosome Study of Some Selected Afroalpine Plants from Bale Mountains, Ethiopia

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Addis Ababa University


Afroalpine plants of the afroalpine environment, the scattered high mountains of Ethiopia and Tropical East Africa, have not been widely studied. Ten species of afroalpine plants were sampled randomly from Bale Mountains and their mitotic chromosomes have been studied or determined using an air-dry method. For chromosome preparation, root tips were pretreated with ice-cold water (24hr) or colchicine (3–4hr), fixed in 3:1 (ethanol:glacial acetic acid) and air-dry slide preparation was made following cellulose-pectinase maceration (37oC,1hr) and stained in Giemsa. For the karyotypic analysis, photographs were taken from the best metaphase plates of each specimen. Ideogram was taken and chromosomes types were determined according to Levan et al., criterion. The result showed that, the chromosome numbers of 2n = 20 for Centella asiatica L.; 2n = 72 for Cotula cryptocephala; 2n = 40 for Senecio nanus; 2n = 56 for Crassula alsinoides; 2n = 28 for Geranium arabicum; 2n = 28 for Lobelia rhychopetalum; 2n = 12 for Plantago major; 2n = 18 for Rumex nepalensis; 2n = 32 for Ranunculus oreophytus and 2n = 32 for Ranunculus multifidus. Karyotypes have been constructed for Senecio nanus, Plantago major and Ranunculus oreophytus species. The first two species have symmetrical karyotype consisting metacentric chromosomes, whereas the latter species showed asymmetrical karyotype with metacentric, sub-metacentric and sub-telocentric chromosomes. The chromosomes length of Senecio nanus, Plantago major and Ranunculus oreophytus range between 2.28 and 11.35μm. Since detailed karyotypic analysis could not be given to the most species under the present study, it is better to carry out further cytological study in the future to get more reliable chromosome data for better understanding about their taxonomic and evolutionary relationships.Key words: Afroalpine environment, Afroalpine plants, Bale Mountains, Chromosome numbers, Chromosomes length, Karyotype, Ideogram.



Afroalpine environment, Afroalpine plants, Bale Mountains, Chromosome, numbers,, Chromosomes length, Karyotype, Ideogram