Genetic characterization of traditional fonio millets (Digitaria exilis, D. iburua STAPF) landraces from West-Africa : Implications for conservation and breeding

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.Fonio Hirsen (Digitaria exilis, D. iburua) gehören zu den wichtigen einheimischen Getreidearten Westafrikas. Sie tragen in den semiariden und gemäßigt feuchten, bzw. von Wassermangel geprägten Gebieten des westlichen Afrika erheblich zur Ernährungssicherung der Haushalte bei. Wegen ihrer generellen wissenschaftlichen Vernachlässigung wird das Potenzial dieser Getreide für die Verbesserung der landwirtschaftlichen Erzeugung und für die Ernährung bisher nicht hinreichend genutzt. Diese Doktorarbeit befasst sich deshalb mit der genetischen Charakterisierung von Fonio, um zur Erweiterung unserer Kenntnisse der Biologie und Genetik dieser Getreidearten beizutragen. Im ersten Teil der Studie wurde eine grundlegende cytogenetische Untersuchung von Fonio-Hirsen und einiger ihrer wilden Verwandten durchgeführt. Die Genomgröße dieser Digitaria-Arten erwies sich als unterschiedlich, während die Arten selbst offensichtlich stabil sind. Außerdem erwies sich die seit längerer Zeit bestehende Hypothese einer cytologischen Variabilität in Fonio als unzutreffend, weil die vorliegende Studie zeigte, dass dieses Getreide ausschließlich tetraploid (2n=4x=36) ist. Auch wurden agro-morphologische Untersuchungen und AFLP-Analysen durchgeführt, um die genetische Diversität in Fonio-Hirsen zu bestimmen sowie die Populationsstruktur und geografischen Verbreitungsmuster zu erfassen. Allgemein wurde ein relativ mäßiger bis geringer genetischer Hintergrund in diesem Getreide festgestellt, der hinsichtlich Erhaltung und Züchtung zu beachten ist. In D. exilis wurde eine strukturierte genetische Diversität und ungleiche Verteilung im Untersuchungsgebiet beobachtet. Die genetische Diversität und phänotypischen Merkmale zeigten nur einen geringen Zusammenhang. Ferner wurden anhand von AFLP-Markern die phylogenetischen Beziehungen der Fonio-Arten mit ihren wilden Verwandten untersucht. Die bestehende Annahme einer direkten Domestizierung von D. exilis und D. iburua, ausgehend von den tetraploiden Wildarten D. longiflora bzw. D. ternata, konnte bestätigt werden. Im letzten Teil der Studie wurden Nachkommenschaftsanalysen sowohl anhand von AFLP als auch von Isoenzymen, Samenansatz und Pollenvitalität durchgeführt, um das Fortpflanzungssystem von Fonio-Hirsen näher zu beschreiben. Wie sich herausstellte, ist Apomixis die dominierende, wenn nicht sogar die ausschließliche Fortpflanzungsweise dieser Getreidearten. Insgesamt stellt die vorliegende wissenschaftliche Arbeit die erste, breitere genetische Charakterisierung von westafrikanischen Fonio-Hirsen dar und trägt so wesentlich zum besseren Verständnis dieser Getreide bei. Die erzielten Ergebnisse sind für das Erhaltungsmanagement und die Nutzung genetischer Ressourcen in der Züchtung von Fonio wichtig. Letztendlich können sie zu einer Steigerung der Fonio-Produktion im westlichen Afrika beitragen

Variation d’expression des symptômes et de l'infectiosité de la maladie de bunchy top chez des cultivars de bananier

Consistent detection of the banana bunchy top disease is important for its management. This study assessed the cultivar differences between cultivars an

Quantitative Analysis, Distribution and Traditional Management of Pigeon Pea [Cajanus Cajan (L.) Millsp.] Landraces’ Diversity in Southern Benin

Pigeon pea (Cajanus cajan (L.) Millsp.) is an important drought tolerant legume cultivated in the semi-arid regions, mainly in Sub-Saharan Africa. Despites its important potential, the crop is neglected and underutilized in many countries including Benin. In order to develop efficient in-situ strategies conservation, a study was conducted to quantify pigeon pea landrace diversity and access its spatial distribution and traditional management by local communities in southern Benin. Therefore, an ethnobotanical survey was conducted in 20 producing villages in southern Benin. Altogether, 26 farmernamed landraces further grouped into five categories were recorded with the number of landraces really cultivated per farmer comparably lower than that listed. Besides, two landraces’ categories were found to be common in the study area while two other were found highly threatened. Diverse parameters such as varietal richness, Shannon-Weaver Diversity Index, Simpson index and Pielou’s evenness were used to quantify pigeon pea diversity that appeared to be unequally distributed through the different agro-ecologies and villages surveyed. The study confirmed the absence of correlations between farmers’ gender and landrace diversity which was nonetheless found to be significantly shaped by the ethnic group and the field size exploited by farmers (P < 0.05). In diversity management, five preference criteria with variable importance across the ethnic groups were used by farmers of which cooking time and market value appeared to be the most important. Exhaustive germplasm collections, morphological/molecular characterizations of these landraces are required for efficient conservation of this important but neglected crop genetic resource in Benin

Evolution de la diversité des cultivars de fonio pratiqués dans la commune de Boukoumbé au Nord-Ouest du Bénin

Afin de comparer la diversité actuelle des écotypes de fonio à celle cultivée dix (10) ans plus tôt au Bénin, une enquête a été menée en 2013 dans la commune de Boukoumbé. Dans chacun des vingt (20) villages prospectés, un focus groupe d’une douzaine de producteurs a été à chaque fois enquêté. Cinq (5) à dix (10) producteurs sont ensuite entretenus individuellement à l’aide d’un questionnaire semi-structuré pour recueillir des informations sur les cultivars, leurs noms locaux, leurs principales caractéristiques, et la gestion des semences. Les résultats ont confirmé la diversité des appellations et ont permis de recenser cinq (5) cultivars différenciés par la précocité, la couleur des racèmes, les tailles de graines et de plantes. Les semences, transmises surtout de génération en génération, sont prélevées à 99% sur les récoltes précédentes. Près de 95% des enquêtés cultivent une seule variété à la fois. La plus forte diversité a été rencontrée chez les "Ditamaris" des villages de Boukoumbé-centre et Natta. "Iporapia" et "Takotapuaka" sont cultivés par toutes les ethnies. La diversité décrite dix (10) ans plus tôt dans la zone a été maintenue. Toutefois, les variétés de précocités extrêmes sont de moins en moins cultivées, et donc menacées de disparition.© 2015 International Formulae Group. All rights reserved.Mots clés: Espèce négligée, accession de fonio, Digitalia spp., conservation in situ, amélioration variétale, BéninEnglish Title: Evolution of the diversity of fonio cultivars practiced in the commune of Boukoumbe in North-West of BeninEnglish AbstractTo compare the current diversity of landraces of millet fonio to that cultivated ten (10) years ago in Benin, a survey was conducted in 2013 in the district of Boukoumbé. In each of the twenty (20) villages surveyed a focus group of a dozen producers was investigated every time. Then, five (5) to ten (10) producers are individually interviewed using a semi-structured questionnaire to collect information on cultivars, their local names, their main characteristics and seed management. The results confirmed the diversity of names and allowed to identify five cultivars differentiated by the earliness, color of racemes, sizes of seeds and plant height. Seeds, especially transmitted from generation to generation, are taken at 99% on the previous harvest. Nearly 95% of respondents grow only one variety at a time. The greatest diversity was encountered among the "Ditamaris" of villages in Boukoumbé center and Natta. "Iporapia" and "Takotapuaka" are cultivated by all ethnic groups. The diversity described ten (10) years earlier in the area has been maintained. However, the extreme precocity varieties are lesser and lesser grown, and therefore at risk of extinction.© 2015 International Formulae Group. All rights reserved.Keywords: Neglected species, accession of fonio, Digitaria spp, in situ conservation, plant breeding, Beni

Variation in symptom development and infectivity of Banana Bunchy Top Disease among four cultivars of Musa sp.

Banana bunchy top disease (BBTD) is an invasive viral disease spreading in Africa. It is transmitted by banana aphids and infected planting material, causing production losses. Clean seeds and timely eradication of diseased plants are effective tools in BBTD management. These depend on timely disease detection. We assessed the relationship between symptom expression and infectivity of the virus in four cultivars of banana. Plantlets from four cultivars, ‘FHIA 25’; ‘Aloga’; ‘Ebenga’ and ‘Sotoumon’, were exposed to viruliferous aphids and monitored for symptom expression. They were also tested as sources for virus transmission fortnightly by allowing non-viruliferous aphids acquisition access prior to transfer to healthy test plants. The time required to show symptoms and the symptom expression were compared, and infection tested by PCR. Disease expression varied from four weeks in ‘FHIA 25’ to fifteen in ‘Sotoumon’. Only the symptomatic leaves tested positive and could act as infection sources. Overall, ‘FHIA 25’ was the most susceptible cultivar, while ‘Sotoumon’ was the least susceptible and most rapidly expressive of BBTD, yet there was no difference in the leaf emergence rate between the cultivars. These results present important aspects of BBTD control and the safety of planting materials that should be tested in the field

Microbiological characterization of the millet-based (Pennisetum glaucum) Ablo and sorghum-based (Sorghum bicolor) Ablo produced in Benin

Ablo is wet bread, slightly salty and sweet, steamed and sold in the form of pellets. The objective of the study was to assess the microbiological quality of millet-based Ablo and sorghum-based Ablo. The methodology adopted was to perform production tests followed by analyses in the laboratory. The results showed that the lactic acid bacteria, yeasts and moulds were the dominant micro flora of the millet- based Ablo and sorghum-based Ablo. Furthermore, analysis showed that the millet-based Ablo and the sorghum-based Ablo doesn’t contain either total coli forms, coli forms thermo tolerant or consequently Escherichia coli. Published by the International journal of Microbiology and Mycology (IJMM

ANTIMICROBIAL, ANTIOXIDANT, CYTOTOXIC ACTIVITIES AND PHYTOCHEMICAL ASSESSMENT OF COLA ACUMINATA USED IN BENIN

Objective: The aim of this study was to make a phytochemical screening and measure some biological activities of Cola acuminata's seeds and leaves extracts.Methods: The secondary metabolite was detected by the method based on coloring and precipitation differential reactions. The antibacterial and antifungal activities were assessed in vitro by the macrodillution and solid medium agar diffusion method. 2,2-diphényl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were used to evaluate the antioxidant activity of the tested extracts of which larval cytotoxicity was studied.Results: Our data revealed that the seeds contain more polyphenols than the leaves. The seeds extracts displayed a good antibacterial activity against both reference strains and food Staphylococcus strains. The inhibition diameters varied from 7±2.82 to 21.5±4.94 mm. The smallest Minimum Inhibitory Concentrations (MIC) on the food strains (0.08 mg/ml) is twice less than the reference strains one (0.15 mg/ml), this observation is contrary to the Minimum Bactericidal concentrations (MBC). Susceptibility of fungal strains varies according to the extracts (p = 0.0016). The seeds ethyl acetate extracts had the best antioxidant activity with DPPH and ABTS methods. The Lethal Doses (LD50) showed that no extract was toxic.Conclusion: Cola acuminata seeds are richer than the leaves in compounds with biological activities. These two organs have interesting antimicrobial, antifungal and antioxidant activity variables depending to the extracts. The seeds have better biological activity than the leaves.Â

Phenotypic diversity for agro-morphological traits in pigeon pea landraces [(Cajanus cajan L.) Millsp.] cultivated in southern Benin

Pigeon pea is an important but unfortunately neglected grain legume crop in Benin. In this study, the phenotypic diversity in 84 landraces from Benin and four advanced varieties were evaluated at two locations during two consecutive rainy seasons. Twelve quantitative and ten qualitative variables were recorded. A wide range of variation was observed in qualitative traits as well as in quantitative variables. The overall Shannon–Weaver diversity index ranged from 0.41 (pod hairiness) to 1.51 (seed colour). Analysis of variance revealed highly significant differences among accessions for all quantitative traits, except the number of seeds per pod, the days to maturity and the seed yield per plant. In all quantitative traits, phenotypic coefficient of variation was higher than genotypic coefficient of variation indicating a substantial environmental effect on their variability. However, some traits (days to flowering, pod width, number of secondary branches and 100 seed weight) showed great value of heritability. Hierarchical clustering on principal components subdivided the collection from Benin into two groups that were clearly separated from the group of advanced varieties. The results gathered from this study have important implications for pigeon pea germplasm characterization and conservation while the inferred phenotypic groups could be used for parental selection and heterotic crossings in pigeon pea breeding in Benin

Variation in Symptom Development and Infectivity of Banana Bunchy Top Disease among Four Cultivars of <i>Musa</i> sp.

Banana bunchy top disease (BBTD) is an invasive viral disease spreading in Africa. It is transmitted by banana aphids and infected planting material, causing production losses. Clean seeds and timely eradication of diseased plants are effective tools in BBTD management. These depend on timely disease detection. We assessed the relationship between symptom expression and infectivity of the virus in four cultivars of banana. Plantlets from four cultivars, ‘FHIA 25’; ‘Aloga’; ‘Ebenga’ and ‘Sotoumon’, were exposed to viruliferous aphids and monitored for symptom expression. They were also tested as sources for virus transmission fortnightly by allowing non-viruliferous aphids acquisition access prior to transfer to healthy test plants. The time required to show symptoms and the symptom expression were compared, and infection tested by PCR. Disease expression varied from four weeks in ‘FHIA 25’ to fifteen in ‘Sotoumon’. Only the symptomatic leaves tested positive and could act as infection sources. Overall, ‘FHIA 25’ was the most susceptible cultivar, while ‘Sotoumon’ was the least susceptible and most rapidly expressive of BBTD, yet there was no difference in the leaf emergence rate between the cultivars. These results present important aspects of BBTD control and the safety of planting materials that should be tested in the field