Somatic Chromosome Study of Some Selected Afroalpine Plants from Bale Mountains, Ethiopia
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Date
2008-07
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Addis Ababa University
Abstract
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.
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Keywords
Afroalpine environment, Afroalpine plants, Bale Mountains, Chromosome, numbers,, Chromosomes length, Karyotype, Ideogram