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
No Thumbnail Available
Date
2010-02
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
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.
Key words/phrases: Embryogenesis, embryo rescue, embryonic tissue, Eragrostis tef, ovary culture, plantlet,
somatic embryo, Triticum spp.
Description
Keywords
Embryogenesis, embryo rescue, embryonic tissue, Eragrostis tef, ovary culture, plantlet, somatic embryo, Triticum spp.