Genetic characterization of traditional fonio millets (Digitaria exilis, D. iburua STAPF) landraces from West-Africa [Elektronische Ressource] : implications for conservation and breeding / by Hubert Adoukonou A. Sagbadja

Hubert Adoukonou A. Sagbadja

Informations

• Publié par: justus-liebig-universitat_giessen
• Publié le: 01 janvier 2010
• Nombre de lectures: 27
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Hubert Adoukonou A. Sagbadja









Genetic Characterization of Traditional Fonio

millets (Digitaria exilis, D. iburua STAPF)

Landraces from West-Africa:
Implications for Conservation and Breeding
Institute of Crop Science and Plant Breeding I
Justus-Liebig University
Giessen, Germany Institute of Crop Science and Plant Breeding I
Justus-Liebig University Giessen






Genetic Characterization of Traditional Fonio Millets (Digitaria exilis,
D. iburua STAPF) Landraces from West-Africa:
Implications for Conservation and Breeding




Dissertation
Submitted for the degree of Doctor of Agricultural Science
at the Faculty of Agricultural Sciences, Nutritional Sciences and Environmental
Management
Justus-Liebig University Giessen



by

MSc. Hubert ADOUKONOU A. SAGBADJA

from

Abomey, Benin Republic
(West-Africa)


Giessen, July 2010




























Board of Examiners:

Chairman of the committee Prof. Dr. Ernst-August Nuppenau
st 1 Referee Prof. Dr. Dr. h.c. Wolfgang Friedt
nd2 Referee Prof. Dr. Wolfgang Köhler
Examiner 1 Prof. Dr Bernd Honermeier
Examiner 2 Prof. Dr. Frank Ordon


Date of oral examination: 19 October 2010



























In memory of my beloved father Awo Edouard
and brother Laurent

























Spiral of the birth of the Universe

“In the mythology of Dogons (tribal group living the cliffs of Bandiagara in Mali),
the grain of Digitaria exilis is the germ of the world, the central nucleus constantly
ejecting other germs with increasing size, in conical spiral motion” (in Griaule and
Dieterlen 1950)

TABLE OF CONTENTS



ABSTRACT
ABBREVIATIONS
Chapter I: GENERAL INTRODUCTION 1
Chapter II: NUCLEAR DNA CONTENT AND FONIO GENOME 21
Chapter III: FONIO GENETIC DIVERSITY AND DIFFERENTIATION 37
Chapter IV: REPRODUCTIVE SYSTEM AND FONIO PHYLOGENY 53
Chapter V: CONCLUDING DISCUSSION 79
SUMMARY 89
ZUSAMMENFASSUNG 92
RESUME 95
APPENDICES 99
ACKNOWLEDGEMENTS
CURRICULUM VITAE
DECLARATION









ABSTRACT
Adoukonou-Sagbadja AH (2010) Genetic Characterization of Traditional Fonio Millets
(Digitaria exilis, D. iburua STAPF) Landraces from West-Africa: Implications for
Conservation and Breeding. PhD thesis, Justus-Liebig University, Giessen, Germany.
With summaries in English, German and French, 107 pp.

Fonio millets (Digitaria exilis, D. iburua) are amongst the important indigenous cereal crops
that greatly contribute to household food security in semi-arid and sub-humid drought-prone
areas of West-Africa. Because of their complete scientific neglect, the potential of these
crops for food and agriculture is not adequately exploited for improvement. This thesis
therefore deals with the genetic characterization of fonio genetic resources with the overall
objective to contribute to our knowledge on the biology and genetics of the crops. In the
primary step of the study, a basic cytogenetic evaluation of fonio millets and some of their
wild relatives was conducted. The genome size among these Digitaria taxa was variable,
while its stability was evident within species. Besides, the longstanding hypotheses on
cytological variability in fonio was not substantiated as the crops were found to be exclusively
tetraploid with 2n=36 chromosomes. AFLP analysis supplemented by agro-morphological
traits evaluation was further performed to quantify the genetic diversity in fonio crops and
assess its population structure and geographical pattern of distribution. Globally, a relatively
moderate to extremely narrow genetic background was detected in these crops, which need
due attention from a conservation and breeding point of view. In D. exilis, the genetic
diversity was structured and unequally distributed in the region. The genetic variability and
phenotypic attributes were loosely correlated. Based on AFLP markers, the molecular
phylogenetic relationships of fonio species with the wild relatives were also inferred. Previous
view of direct domestication of D. exilis and D. iburua from the wild tetraploid D. longiflora
and D. ternata, respectively, was confirmed. In the last step of the study, progeny analysis by
both AFLP and isozymes, seed set determination and pollen viability test were conducted to
determine the reproductive system in fonio millets. Apomixis was found to be the major (if not
the absolute) mode of reproduction in these crops. The present work constitutes the first
large scale genetic characterization of West-African fonio millets and substantially adds to
the general scientific understanding of the crops. The diverse results obtained are relevant
for conservation management and exploitation of fonio genetic resources in breeding that,
ultimately, may boost fonio production in West-Africa.

KEYWORDS: AFLPs, Breeding, Conservation, Cytology, Digitaria spp., Fonio, Genetic
diversity, Isozymes, Phylogeny, Morphology, Reproductive system, West-
Africa

Author’s present address: Department of Plant Breeding, Research Centre for BioSystems,
Land Use and Nutrition, Justus-Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392
Giessen, Germany

Author’s home address: Laboratory of Genetics and Biotechnology, Faculty of Sciences and
Techniques (FAST), University of Abomey-Calavi, BP 526 Cotonou, Benin. Email:
[e-mail]