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Micropropagation, transformation and genetic diversity of Hagenia abyssinica (Bruce) J.F. Gmel.

Feyissa, Tileye (2006). Micropropagation, transformation and genetic diversity of Hagenia abyssinica (Bruce) J.F. Gmel. Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2006:4
ISBN 91-576-7053-6
[Doctoral thesis]

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The tree species Hagenia abyssinica belongs to a monotypic genus in the family Rosaceae. It grows on the highlands of tropical Africa, where it is seriously endangered principally due to high timber demands. Therefore, the establishment of fast and efficient biotechnological methods to propagate and improve different traits of interest is much needed. The objectives of this study were to establish micropropagation and in vitro regeneration protocols and to transform this species with the rolB gene to improve the rooting efficiency. In addition, a study of genetic diversity was needed to provide information for in situ and ex situ conservation. A micropropagation protocol has been developed using explants from both juvenile and mature tree sources. These explants were initiated, multiplied and rooted using either WPM or MS medium and different combinations of BAP and IBA. Using leaves from in vitro grown shoots of juvenile or mature tree origin, an in vitro regeneration protocol has been developed based on using TDZ alone or in combination with NAA or 2,4-D. Regeneration efficiency was also studied using TDZ or BAP in combination with IAA. The effects of wounding, kanamycin and cefotaxime on regeneration have been studied. TDZ was found to be the best cytokinin for regeneration of H. abyssinica at low concentrations since it promotes direct shoot regeneration, as well as at high concentrations since it promotes callus induction and shoot regeneration although it inhibits shoot elongation. All auxins appeared to be toxic to H. abyssinica, particularly at higher concentrations. Based on the results of these regeneration experiments, H. abyssinica was transformed with the rolB gene. One clone of the transformants exhibited 77% rooting while no roots were produced by any of the untransformed control shoots. Kanamycin was found to be the main factor inhibiting the recovery of transformants whereas cefotaxime is toxic only at high concentrations. Since somaclonal variation of micropropagated plants is highly undesirable, genetic stability was tested on 80 micropropagated plants, 40 of axillary origin and 40 from adventitious shoots. These plants had been grown in vitro for over two years when they were screened with randomly amplified polymorphic DNA (RAPD) markers. Only one plant, originating from an axillary shoot, deviated by showing two extra bands thus indicating that H. abyssinica is relatively stable in vitro. A genetic diversity study based on inter simple sequence repeats (ISSR) was conducted on a total of 120 samples representing 12 populations from different parts of Ethiopia. This study showed that within- and between-population variability in H. abyssinica is typical of an outcrossed, perennial, late-successional species. Two recently planted populations and one indigenous primary forest-population showed the highest diversity. An autocorrelation analysis between genetic and geographic distances indicated that gene flow takes place over only about 30 km and this is likely to decrease even further because of genetic isolation among populations brought about by the current logging practices.

Authors/Creators:Feyissa, Tileye
Title:Micropropagation, transformation and genetic diversity of Hagenia abyssinica (Bruce) J.F. Gmel.
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2006
Number of Pages:36
ALLI. Feyissa, T., Welander, M. & Negash, L. 2005. Micropropagation of Hagenia abyssinica: a multipurpose tree. Plant Cell ,Tissue and Organ Culture 80, 119-127. II. Feyissa, T., Welander, M. & Negash, L. 2005. In vitro regeneration of Hagenia abyssinica (Bruce) J.F. Gmel. (Rosaceae) from leaf explants. Plant Cell Reports 24, 392-400 III. Feyissa, T., Zhu, L.H., Negash, L. & Welander, M. Regeneration and genetic transformation of Hagenia abyssinica (Bruce) J.F. Gmel. (Rosaceae) with rolB gene. (Submitted). IV. Feyissa, T., Welander, M. & Negash, L. Genetic stability, ex vitro rooting and gene expression studies in Hagenia abyssinica. (Submitted). V. Feyissa, T., Nybom, H., Bartish, I. V. & Welander, M. Analysis of genetic diversity in the endangered tropical tree species Hagenia abyssinica using ISSR markers. (Submitted).
Place of Publication:Alnarp
ISBN for printed version:91-576-7053-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
Subjects:Not in use, please see Agris categories
Agrovoc terms:rosaceae, genetic variation, in vitro variation, rooting, etiopia
Keywords:Hagenia, in vitro regeneration, inter simple sequence repeat (ISSR), micropropagation, rolB gene, rooting, transformation
Permanent URL:
ID Code:1019
Department:?? 4806 ??
Deposited By: Tileye Feyissa
Deposited On:10 Jan 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

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