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Title: Regeneration of plants from unpollinated ovary cultures of Ethiopian wheat varieties (Triticum spp.) and embryo rescue cultures of F1 hybrids of tef [Eragrostis tef (Zucc.) Trotter)] with its wild relatives
Authors: Tsegaye, Getahun Bogale
Advisors: Dr. Tileye Feyissa
Keywords: Triticum spp
somatic embryo
plantlet
ovary culture
Eragrostis tef
embryonic tissue
embryo rescue
Embryogenesis
Copyright: Feb-2010
Date Added: 10-May-2012
Publisher: AAU
Abstract: Tef [Eragrostis tef (Zucc.) Trotter] and wheat (Triticum spp.) are the two top staple cereal crops in Ethiopia. Production constraints of cereal crops include fungal and viral diseases, insect pests, less quality and quantity of food grains, late maturation, lodging and others. For gynogenic cultures, unpollinated ovaries were excised from four varieties of wheat (Triticum spp.), two varieties from each of durum and bread wheat namely Yerer, Ude, Simba and Galema respectively. Light and dark culture conditions, durations of cold pretreatment at 4 oC, stages of harvesting, seasons, genotypes, types of media and compositions of the media affected induction of direct embryogenesis. ANOVA has shown that genotypes, stages of harvesting, types of media, combinations of PGRs (2,4-D and KIN) and durations of cold pretreatment at 4 oC significantly (P≤0.05) affected formation of embryonic tissues independently. Developmental stages of the donor plants were critical step in gynogenic response of cereal crops. Developmental stages of wheat spikes were identified and stage II was taken as the best stage for induction of embryonic tissues. Furthermore, light culture conditions, 30 g/l of maltose, MS medium, and 15 days of cold pretreatment were the best conditions for induction of embryonic tissues. From 12 combinations of 2,4-D and KIN supplemented in MS basal medium, 1 mg/l of each of 2,4-D and KIN was found to be the best combination for induction of embryonic tissues for varieties Yerer (35.0 %), Simba (26.6%) and Ude (13.3 %). Eleven different PGR combinations were used for shoot regeneration, 0.1 mg/l of NAA + 1 mg/l KIN was the PGR combination where the embryonic tissues of all varieties regenerated into shoots. The highest frequency of shoots were regenerated from the cultured embryonic tissues of varieties Simba (41.3 %) and Yerer (41.6 % ) at 0.1 mg/l 2,4-D. From a total of 14,524 cultured ovaries, 1100 embryonic tissues (7.6 %) and 75 regenerants were obtained. The average percentage of embryonic tissues and regenerants were 9.0 % and 1.1 % from 3,444; 9.8 % and 0.55 % from 4,732; 5.6 % and 0.17 % from 2,988; 4.7 % and 0.12 % from 3,360 cultured ovaries for varieties Yerer, Simba, Ude and Galema respectively. In embryo rescue cultures, 8 combinations from 2 wild species of tef: E. pilosa (30-5), E. pilosa (37 80 82) and E. curvula and 4 domesticated varieties of tef: E. tef cv. Kaye Murri, E. tef cv. DZ-Cr-387, E. tef cv. DZ-Cr-37 and E. tef cv. DZ-01-196 were taken. Florets were cultured in MS medium supplemented with 6 different concentrations of 2,4-D which were excised from panicles after six days of artificial crossing, 1 mg/l 2,4-D and 0.1 mg/l of 2,4-D were found to be the best 2,4-D concentrations for induction of somatic embryos from the cross of E. pilosa*Kaye Murri (46.7 %) and E. pilosa*DZ-Cr-37 (13.3 %) respectively. From a total of 635 cultured florets of F1 hybrids, 21 somatic embryos of F1 hybrids were obtained . Of which 19 somatic embryos from the cross of E. pilosa (30-5)*Kaye Murri and 2 somatic embryos from the cross of E. pilosa (30-5)*DZ-Cr-37 were obtained. Fourteen somatic embryos (73.7 %) and 1 somatic embryo (50 %) were regenerated in half MS medium without plant growth regulators respectively. Twenty four plantlets of F1 hybrids of E. pilosa (30-5)*Kaye Murri were successfully transferred into pots. A total of 442 single plantlets were regenerated at maturity that were uniform, normal, fertile and no abberant plants were obtained. The plantlets showed inherited characteristics from both parents. It is recommended that the temperature of the growthroom and glasshouse should be adjusted for better survival of plantlets. Appropriate focus and facilities should be given for crossing of tef in order to avoid its bottlenecks with modern biotechnology.
URI: http://hdl.handle.net/123456789/2934
Appears in:Thesis - Biology

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