Chromosome Study of Local Farmers’ Varieties of Opuntia ficus-indica (L.) Mill. (Cactaceae) from Tigray, Northern Ethiopia
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Date
2010-12
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Addis Ababa University
Abstract
Opuntia ficus-indica (L.) Mill. is one of the drought resistant plants that play a significant
role in rescuing the lives of people and livestock in arid and semiarid regions of the world. In
Ethiopia, particularly in Tigray, it is used as food and forage until cereal crops are harvested
as well as during drought seasons. Currently, about thirty-four local farmers’ varieties of O.
ficus-indica are locally identified in the Southern and Eastern Zones of Tigray on the bases of
their fruit characteristics and cladode morphology. The present study tried to assess the
cytogenetic variability among these local farmers’ varieties through standard chromosome
count method. Other three sample plants of opuntia species from Debre-zeyit, Dire Dawa
and Addis Ababa were also included in the study for comparison of their chromosome count
with that of the specimens collected from Tigray. The results of the study have shown that all
the sample plants chromosomally investigated in the study are polyploids. All the local
farmers’ varieties of O. ficus-indica, for which the somatic chromosome spreads were
reliably counted, were found to have an octoploid cytotype, with the same somatic
chromosome number of 2n = 8x = 88. The two specimens of O. ficus-indica plant, each from
Debire-zeyit and Dire Dawa, have also shown the same ploidy level and somatic
chromosome number with that of the local farmers’ varieties of O. ficus-indica collected from
Tigray. On the other hand, the specimen of O. cylinderica plant collected from Science
Faculty Campus of Addis Ababa University was found to have a different ploidy level with
different somatic chromosome number of 2n = 11x = 121.
The fact that all the local farmers’ varieties of O. ficus-indica included in the present study
belong to the same ploidy level indicates that the variations among those local farmers’
varieties in fruit characteristics and cladode morphology could not be attributed to the
variation in ploidy level. Further chromosome studies were also recommended to cover wider
populations of O. ficus-indica from different parts of Ethiopia. It was also recommended to
investigate the polyploidy nature, mode of seed formation and genetic variability of O. ficusindica
using appropriate molecular techniques such as ISSR and AFLP.
Key words: Chromosomes, Local farmers’ varieties, Opuntia ficus-indica,
Polyploidy, Tigray.
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Keywords
Chromosomes, Local farmers, varieties, Opuntia ficus-indica, Polyploidy, Tigray