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Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/949

Authors: Likeyelesh, Gugsa
Advisors: Professor Dr. Horst Lörz
Keywords: Eragrostis tef, ovary, immature embryo, rescue, pistil, microspores, haplodization,androgenesis, embryonic tissue, gynogenesis, biolistic and agro-bacterium transformation.
Copyright: 2005
Date Added: 24-Apr-2008
Publisher: Addis Ababa University
Abstract: ABSTRACT The four objectives of this PhD study were to develop protocols for embryo rescue technique, efficient plant regeneration system from immature embryos, in vitro haplodization either through androgenesis or gynogenesis and transformation in Eragrostis tef. The major study materials include were three tef varieties, improved, DZ-01-196 and DZ-CR-37, a farmers variety, Fesho and the wild, relatives E mexicana, .E, pilosa and E.papposa. For embryo rescue study, both zygotic embryos and ovaries at early stage of self pollination were excised and cultured in the medium. More than 90 % rescue was recorded for tef varieties from both explants. Similar results were obtained from some wild species from embryo culture. DZ-01-196 performed better than DZ -CR-37 and Fesho in both explant types.A highly efficient in vitro culture system was also developed using immature embryos of tef. Efficiency was examined by the embryogenic calli formation, plant regeneration and number of shoots per explant obtained. 100 % somatic embryo formation, 98.2% plant regeneration as well as maximum number 565 plantlets per single explant were obtained from variety DZ-01-196. This highly efficient technique developed here will be very useful for further studies like transformation which required high plant regeneration system. In androgenesis study factors influencing androgenic response were investigated. 0.15 % of calli were induced from the cultured microspores and only one albino plant was obtained. This result showed that tef is recalcitrant to androgenesis. Therefore, in vitro gynogenesis was attempted. Out of 14234 cultured unpollinated pistils, 2035 embryonic tissues and 13.4 %. regeneration were obtained The flow cytometry analysis of these plants revealed 5 haploids (di-haploids), 2, aneuploids, 172, tetraploids and 1 octoploid plant. Haploid and variant polyploidy plant production in tef is for the first time. For tef transformation study, genes for selectable marker and reporter genes were used and 4 transformed plants from biolistic and 1 transgenic plant from agrobacterium method survived the repeated sub culturing on selection media. Transgenic plants, recovered after 4-6 weeks from the time of gene transfer were subjected to PCR and southern blot analysis. The result revealed from T1 plants stable transformation from both transformation system. This protocol will contribute for the improvement of the crop in the near future. Key words: Eragrostis tef, ovary, immature embryo, rescue, pistil, microspores, haplodization, androgenesis, embryonic tissue, gynogenesis, biolistic and agro-bacterium transformation.
Description: A Ph.D Thesis Submitted to the School of Graduate Studies, Addis Ababa University, in Partial Fulfillment of the Requirement for the Degree of Doctor of Philosophy in Biology
URI: http://hdl.handle.net/123456789/949
Appears in:Thesis - Biology

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