Fonio is an ancient orphan cereal, cultivated by resource-poor farmers in arid and semi-arid regions of West Africa, who conserved and used the cereal for nutrition and income generation. However, the extent and patterns of phenotypic variation within the fonio germplasm remain scarcely evaluated to inform breeding decisions. In this study, we used alpha lattice design to assess the phenotypic variability of 180 fonio accessions using 20 agro morphological descriptors, including both qualitative and quantitative traits at Bengou research station in 2018 and 2019. Descriptive statistics, combined analysis and multivariate analyses, including principal components analysis (PCA), hierarchical clustering, and multiple factor analysis (MFA) were performed. As results, we found significant differences among fonio accessions and among agro ecological zones of provenance for most of the quantitative traits. Furthermore, highly significant positive correlations were found between grain yield and other yield-related attributes such as harvest index and thousand seeds weight, whereas significant negative correlations were found between grain yield and flowering and maturity times. Clusters analysis revealed three phenotypic groups. Group 1 was characterized by early maturing fonio accessions with higher grain yield. Groups 2 and 3 were characterized by late maturing accessions with intermediate to moderate grain yield. The accessions from Group 1 are candidate for yield improvement and development of fonio lines with enhanced lodging resistance. Accessions from Group 2 and 3 can be improved for yield through marker-assisted selection of best thousand seed weight. This study highlights how traits are correlated within the major phenotypic groups of fonio in West Africa, and we discussed how these groups could be further exploited for improving traits of economic importance. Furthermore, this study exhibited agro morphological descriptors that discriminate fonio accessions and provide useful information for parental selection with economically important agronomic traits.

Orphan small grain cereals highly contribute to food and nutrition security worldwide, although the genetic and genomic resources for these cereals are far less available compared to major grain cereals. Consequently, there is low progress in their genetic improvement notwithstanding the high nutrient content, diversity, and health benefits of many of them. Therefore, additional efforts are expected to improve our understanding of the genes related to important agronomic traits. In this review, we provide an overview of achievements and bottlenecks in orphan small cereals improvement. We point out the need for the generation of basic knowledge that should guide the initial breeding process of orphan small cereals. Focusing on fonio, we showed how conventional breeding combined with advances in next‐generation sequencing technologies could potentially speed up the genetic improvement of the crop. Furthermore, a comprehensive action plan that integrates research, technological development and dissemination, and value chain improvement was illustrated in this review. These actions will foster the economy of West African fonio millet through wider cultivation, marketing, and consumption.

Social Impact Statement: The use of neglected and underutilized species (NUS) in agrosystems is a potential solution to the challenges arising from global change. These species could contribute to the equitable diversification of agricultural systems. Providing knowledge on their genetic diversity and fostering access to data and results is essential for the development of strong collaborative future research. The study addressed these issues by assessing the diversity of the largest fonio (Digitaria exilis) collection existing to date. Associated with a user‐friendly Shiny application (https://shinyapps.southgreen.fr/app/foniodiv), our results reinforce research efficiency and broaden the prospects for all actors involved in enhancing fonio and indigenous crops as valuable resources for the future.

White fonio (Digitaria exilis) is a staple food for millions of people in arid and semi-arid areas of West Africa. Knowledge about nutritional and health benefits, insights into morphological diversity, and the recent development of genomic resources call for a better understanding of the genetic structure of the extant germplasm gathered throughout the region in order to set up a robust breeding program. We assessed the genetic diversity and population structure of 259 fonio individuals collected from six countries from West Africa (Nigeria, Benin, Guinea, Mali, Burkina Faso and Niger) in this study using 688 putative out of 21,324 DArTseq-derived SNP markers. Due to the inbreeding and small population size, the results revealed a substantial level of genetic variability. Furthermore, two clusters were found irrespective of the geographic origins of accessions. Moreover, the high level of linkage disequilibrium (LD) between loci observed resulted from the mating system of the crop, which is often associated with a low recombination rate. These findings fill the gaps about the molecular diversity and genetic structure of the white fonio germplasm in West Africa. This was required for the application of genomic tools that can potentially speed up the genetic gain in fonio millet breeding for complex traits such as yield, and other nutrient contents.

Plant genetic resources characterization is essential for their conservation and their use in both breeding strategies and adaptation to global change. This is all the more important for species often neglected by research such as fonio. Fonio refers to two indigenous small millets grown in West Africa, white and black fonio (Digitaria exilis and Digitaria iburua, respectively). This research was carried out to develop a simple and reliable method to identify the two cultivated species of fonio in the context of genebank collection. A morphometric analysis was performed on seeds of 98 accessions of D. exilis and 20 accessions of D. iburua. Morphometric characters measured were seed dimensions, shape and colour. We showed that the major delimiting criterion was the seed width and that the seeds of black fonio were wider than those of white fonio. The proposed method, based on seed morphometrics, could be applied systematically in conservation routine to guarantee the accuracy of the passport data in fonio collections, as well as to identify fonio remains for archaeological studies.