Plant Breed. Biotech. 2020 (June) 8(2):77~88 Online ISSN: 2287-9366 https://doi.org/10.9787/PBB.2020.8.2.77 Print ISSN: 2287-9358 REVIEW ARTICLE Genetic Resources and Varietal Environment of Grown Fonio Millets in West Africa: Challenges and Perspectives 1 1 2 Cyrille Kanlindogbe *, Emmanuel Sekloka , Emmanuel Hala Kwon-Ndung 1 Laboratory of Phytotechny, Plant Breeding and Plant Protection, Faculty of Agronomy, University of Parakou, Parakou 123, Benin 2 Department of Botany, Federal University of Lafia, Lafia 950101, Nigeria ABSTRACT Fonio, known to be the smallest and oldest form of millet grown in sub-Saharan Africa, has remained relatively poor of research despite its nutritional, sociocultural, agroecological, therapeutic and economic potentials. Based on systematic literature review, this critical study showed that fonio genetic breeding progress is at a low level. Genetic resources are threatened by erosion, particularly extra-early cultivars of Digitaria exilis, and mainly D. iburua species have practically disappeared in some cultivation countries including Benin. Varietal environment is characterized by lack of improved varieties and seeds, so that cultivars are ecotypes derived from natural selection often with low yields. Seeds, very tiny, are generally heterogenous, in polyvarietal mixtures because of unimproved systems and management by farmers. These ecotypes are susceptible to stem lodging and seed shattering. An exhaustive list of fonio genetic resources from West and Central Africa into catalog remains to be documented. There is a need for regional and international networking of fonio researchers with institutional support for harmonizing germplasm characterization methods, will facilitate descriptors development for all countries. It is necessary to consider in this work wild relative species that have potential genes of resistance/tolerance to biotic and abiotic stress. Starting from autogamy and apomixis revealed on fonio, homogenization program using pureline and mass selection of cultivars could enable rapid release of homogeneous and higher yielding materials to farmers and processors. Development of early and yielded varieties, with upright stem and coarse grains, resistant to lodging, shattering, and facilitating mechanical harvesting would enhance effective production revival. Keywords Genetic erosion, Networking, Catalog and descriptors, Selection, Improved varieties of fonio, Africa INTRODUCTION neglected species that is a staple food for populations in several West African countries (Cruz et al. 2011). It plays Conservation and sustainable exploitation of traditional a crucial role in food security of thousands of people around phytogenetic resources is now a major concern for agri- the world, especially with early cultivars harvested often culture and scientific research. Indeed, it is estimated that early that serve to get through the lean season (Dramé and nearly three-quarters of crop genetic diversity has been lost Cruz 2002; Paraïso et al. 2011; Sekloka et al. 2016). In the in the last century, and this genetic erosion continues (Con- world, apart from Panicum miliaceum and Setaria italica vention on Biological Diversity, http://fr.wikipedia.org/ from the sub-temperate countries, there are not yet small wiki/Convention_sur_la_diversit%C3%A9_biologique). cereals cultivated by a large number of small producers This is the case of neglected and underutilized food species (Portères 1955; CIRAD 2009). Cultivated often without of the tropical world, which today represent an unexplored chemical inputs, fonio contributes to environment protec- pool of diversities and potentialities. tion (CIRAD 2009; Cruz et al. 2011). Recognized for its Fonio (Digitaria exilis S., D. iburua S.) is one of these nutritional, medicinal and socio-cultural importances (Jideani Received January 7, 2020; Revised March 6, 2020; Accepted April 9, 2020; Published June 1, 2020 *Corresponding author Cyrille Kanlindogbe, [email protected], Tel: +229-23-61-20-10, Fax: +229-23-61-20-10 Copyright ⓒ 2020 by the Korean Society of Breeding Science This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 78 ∙ Plant Breed. Biotech. 2020 (June) 8(2):77~88 1999; Adoukonou-Sagbadja et al. 2006; Ballogou 2013), fonio) and Digitaria iburua (black fonio) are the two fonio is intended to be a cereal of the future. However, it has species grown in West Africa. Digitaria sanguinalis (Euro- remained a long-time marginal plant and poor relative of pean millet or red manna) is produced in Eastern Europe research. In all areas of West Africa where this cereal is and Digitaria cruciata (raishan) practiced in India and grown, very little attention is paid to the assessment and Vietnam (Froment and Renard 2001; Vodouhè and Achigan breeding of its germplasm (Hilu et al. 1997; Sekloka et al. Dako 2006). Today, Digitaria exilis and D. iburua, the 2016; Animasaum et al. 2018). It is still little known from most species cited in the literature, dominate the biodiver- morphological, agronomic, physiological or even biologi- sity of digitaria genus. Better, only D. exilis is much more cal point of view so that it is difficult to determine with cultivated and even outside Africa, it is grown in Dominican precision extent of its diversity and cultivated varieties of Republic mainly for fodder production (Morales-Payán et fonio. With this in context, this study aims at making a al. 2002). critical documentary synthesis on genetic resources diver- Fonio origin dates back to 5000 years before J-C and has sity and varietal environment of fonio so as to identify been domesticated in the western part of Sudan (Vodouhè challenges and prospects for breeding. et al. 2003). White fonio comes from the Niger Delta region and Togo would be secondary center of diversification Methodology (Portères 1955; Vodouhè et al. 2003). Black fonio, on the This study involved a systemactic literature search on other hand, is related to Haoussa culture and is believed to genetic resources and varietal breeding of fonio in different be native to Nigeria from where it is spread to Zinder in crop areas in West Africa. Thus, the keywords “fonio gene- Niger, Benin, and Togo (Porteres 1946; Haq and Ogbe 1995; tic resources_ biology and reproduction_related species Vietmeyer et al. 1996). and genetic reservoir_agro-morphological classification In West Africa, fonio growing area extends between the th th and phenotypic discrimant traits_ markers and molecular 8 and 14 parallel north, from Senegal to Lake Chad characterization of fonio” have been submitted for collect- (Portères 1976; Cruz et al. 2011). Digitaria exilis is mainly ing the literature available via Google Scholar, AJOL, grown in Guinea, Mali, Burkina Faso, Nigeria, Benin, DOAJ, ResearchGate, ScienceDirect, JSTOR and AGORA. Togo, Senegal and Guinea Bissau (Adoukonou-Sagbadja This search has led to more than 800 documents of different 2010; Cruz et al. 2011) whereas D. iburua has weak geo- kinds (articles, conference papers, theses, dissertations, re- graphic extension (Fig. 1) concentrating mainly in parts of ports and statistical data). Selective sorting based on the Central Nigeria (Kwon-Ndung et al. 1998). choice of documents addressing the sub-themes developed, and prioritizing scientific publications has enabled to re- Phylogenic relationships and interests for fonio duce the number of documents and to retain 62 papers in breeding this article. This documentation has been subjected to sys- First work early reported important botanical and geo- temic and critical analysis. Thus, the results of analysis graphical similarities of grown fonios (Digitaria exilis and have been presented in the form of literature synthesis, D. iburua) with several wild species of Digitaria genus (D. tables and figures. longiflora, D. barbinodis, D. fuscescens, D. ternata, D. tricostulata, D. atrofusca) (Stapf 1915; Henrard 1950; Haq Origin, domestication, and distribution areas of and Ogbe 1995). cultivated fonios Further, phylogenetic researches based on molecular Designated from the Malinke patois of Upper Senegal markers (RAPD, RFLP, AFLP, SSR, etc.) carried out to and Upper Niger, fonio is one of the first cereals grown in date have unanimously shown that Digitaria longiflora and West Africa (Portères 1955; Adoukonou-Sagbadja et al. D. ternata were the most likely wild relatives of Digitaria 2006). The biodiversity of fonio millet includes four (4) exilis and D. iburua respectively (Table 1). Among these cultivated species around the world. Digitaria exilis (white grown fonios, molecular analyzes also revealed differentia- Genetic Resources and Varietal Environment of Grown Fonio Millets in West Africa ∙ 79 Fig. 1. Fonio cultivation areas in West Africa. Source: Map reproduced from Portères (1976), Adoukonou-Sagbadja (2010), Cruz et al. (2011). Table 1. Phylogenetic studies and diversity of grown fonios. References Used Markers Obtained results Hilu et al. (1997) RAPD High genetic diversity of fonio (D. exilis), and confirmation of D. longiflora and D. temata as wild relatives of D. exils and D.iburua respectively Adoukonou-Sagbadja AFLP Very high genetic affinity with more than 92% similarity noted between wild species et al. (2010) D. longiflora and D. ternata respectively with those