Feyissa, Tileye (PhD)Disasa, Tesfaye2018-07-112023-11-082018-07-112023-11-082007-08http://etd.aau.edu.et/handle/123456789/8092Callus induction and shoot formation from hypocotyls and cotyledons of Guizotia abyssinica Cass. has been achieved in this experiment. The frequency of callus induction was influenced by the concentrations and types of growth regulators. Six to eight-day-old hypocotyl segments and cotyledons were cultured on MS medium containing different concentrations of NAA, IAA and BAP. Among the various concentrations tested, 0.5 mg/l NAA in combination with 1 mg/l BAP was found to be the best for maximum callus induction of hypocotyl explants. Furthermore, 2 mg/l IAA in combination with 1 mg/l BAP was the best for callus induction of cotyledonary explants. Highest percentage of shoot formation (60%) was obtained when cotyledons were cultured on medium supplemented with 3.0 mg/l IAA in combination with 1.0 mg/ l BAP. Maximum number of shoots per explant (20.3) was obtained from medium containing 0.1 mg/l NAA in combination with 1 mg/l BAP. The types of explant, growth regulator combinations and genotypes were showed significant effect on shoot regeneration. The elongated shoots were successfully rooted on media supplemented with IBA at a concentration of 0.5 mg/l. The shoots were established in soil where 65% of them survived. Morphologically aberrant plants were not observed. As plant regeneration protocol is a prerequisite for genetic transformations, this protocol can be used for such purposes and development of new varieties with desired traits by in vitro selectionenBiologyThesis