Grasses (Poaceae) From Senegal: New Records Checklist, Biogeographical Affinities and Biological Types

Poaceae is one of the most diverse families in Senegal's flora after Fabaceae. It has been the subject of several studies but many species were not taken into account in the evaluation of the current state of its diversity. This paper provides a checklist of new grasses encountered in Senegal. After a detailed scrutiny of the literature and herbarium specimens, we ascertain their identity and report them as new records to the grass flora of Senegal. A total of 24 new species have been listed belonging to 15 genera of which the most represented is Sporobolus with 5 species. The other genera such as Digitaria, Eragrostis, Perotis, Setaria, and Trichanthecium on the one hand and Aristida, Chloris, Cymbopogon, Enteropogon, Leptochloa, Oryza, Panicum, Schizachyrium, Urochloa on the other hand have two and one species respectively. The chorological spectrum shows the dominance of African species (45.83%) followed by those of Afro-Asian origin (33.33%). Like the overall flora of Senegal, this new grass flora is of tropical nature with a preponderance of Sudano-Zambesian species (50%) followed by Guinean- Congolese-Sudano-Zambesian species (29.17%) at continental scale. Biological types based on the life form shows therophytes (62.50%) are predominant, followed by hemicryptophytes (29.17%) and geophytes (8.33%). Taking these new data into account would allow a more precise determination of the Senegalese grass flora composition

Structure et caractéristiques de la flore adventice de la ferme agricole de l’Université Gaston Berger de Saint-Louis (Sénégal)

This present study was conducted to determine the structure and characteristics of the adventitious flora of the agricultural farm of Gaston Berger University (UGB) located in Saint Louis, Senegal. A species inventory was carried out using the "tour de champ" technique which consists of going through a plot in different directions and recording all the species present in the studied area. The inventoried flora is composed of 149 species distributed among 90 genera belonging to 30 families which are dominated by the Poaceae (18.8%) and the Fabaceae (15.4%). This flora is also characterized by the predominance of the therophytes and the chamephytes which represent 79.9% and 10.7% of recorded species, respectively. From a chorologic standpoint, pantropical (29.5%) and African (28.2%) species account for more than half of the species (57.7%). The quantitative analysis of this flora reveals that rare or accidental species are more represented (52%) followed by frequent species (16%) and secondary species (15%)

Study of the woody flora in the mining areas of the commune of Sabodala (Kédougou, Senegal)

Le Sénégal oriental est une région très riche de par sa flore, sa faune mais également de par son sous-sol qui renferme d’intéressants indices ou gisements d’or, d’uranium, de fer, de cuivre, de nickel, de lithium, de marbre, de molybdène et de chrome. Cette exploitation n’est toutefois pas sans conséquences car les activités extractives causent d’énormes préjudices notamment à l’environnement. La présente étude se fixe comme objectif d’établir la situation de référence de la flore ligneuse de la zone. Ainsi à partir d’un échantillonnage de type aléatoire stratifié et d’un maillage systématique, l’étude de la flore du site a été faite en utilisant la méthode de l’inventaire itinérant. La flore de la zone d’exploitation minière de la commune de Sabodala et ses environs est riche de 103 espèces distribuées dans 75 genres et 32 familles. Les Fabaceae, Combretaceae et Malvaceae sont les familles majoritaires de cette flore. Le genre Combretum est le plus riche avec 7 espèces. Le spectre biologique montre une prédominance des microphanérophytes et des mésophanérophytes. Les espèces de l’élément-base soudanien sont majoritaires avec 35,3 %, indiquant le caractère soudanien de la zone. Ces résultats sont très importants dans les processus de reconstitution de la flore de la zone. Mots-clés: flore ligneuse, Goumbati-Kobokoto, savanes, zone soudanienneEastern Senegal is a very rich region for its flora and fauna but also for its subsoil which contains interesting gold, uranium, iron, copper, copper, nickel, lithium, marble, molybdenum and chromium deposits. However, this exploitation is not without consequences, as mining activities cause enormous damage, particularly to the environment. The objective of this study is to establish the reference situation of the woody flora of the area. Thus, using stratified random sampling and a systematic grid, the study of the site's flora was carried out using the mobile inventory method. The flora of the mining area of the commune of Sabodala and its surroundings is rich in 103 species distributed in 75 genera and 32 families. The Fabaceae, Combretaceae and Malvaceae are the majority families of this flora. The Combretum genus is the richest with 7 species. The biological spectrum shows a predominance of microphanerophytes and mesophanerophytes. The species of the Sudanian base element are the majority with 35.3%, indicating the Sudanian character of the area. These results are very important in the processes of reconstitution of the flora of the zone. Keywords: woody flora, Goumbati-Kobokoto, savannas, Sudanian zon

Révision du genre Digitaria Haller (Poaceae) au Sénégal : proposition d’une clé de détermination pour une meilleure identification des espèces

Le genre Digitaria Haller (Poaceae) constitue l’un des genres les plus diversifiés des Poaceae du Sénégal avec 19 espèces. Bien qu’il y ait une monographie mondiale du genre, la détermination des espèces reste difficile et repose essentiellement sur les caractères de l’appareil reproducteur. Ce travail, qui est une révision du genre Digitaria au Sénégal, est entrepris afin de rechercher des caractères pertinents sur l’appareil végétatif et d’améliorer l’identification des espèces. Pour ce faire, une description détaillée des différents organes des spécimens étudiés est réalisée à l’aide d’une loupe binoculaire. Les résultats de l’étude montrent que la pubescence de l’épillet est un caractère essentiel pour l’identification des espèces. De plus, les longueurs relatives de la glume supérieure et de la lemma inférieure sont très intéressantes pour la discrimination d’espèces affines. Toutefois, l’étude supplémentaire des organes végétatifs de la plante adulte montre que certains caractères végétatifs pourraient contribuer considérablement à l’amélioration de l’identification des espèces. Il s’agit du cycle biologique, de la pubescence de la ligule, de la marge du limbe, des noeuds et des entre-noeuds du chaume qui sont des caractères plus faciles à observer. Une clé de détermination basée sur des caractères végétatifs et reproducteurs des espèces est ainsi élaborée.© 2015 International Formulae Group. All rights reserved.Mots clés: Digitaria, Poaceae, révision, clé de détermination, SénégalEnglish Title: Review of Digitaria Haller (Poaceae) genus in Senegal: suggestion of a determination key for a better identification of speciesEnglish AbstractThe genus Digitaria Haller (Poaceae) is one of the most diversified genera of Poaceae in Senegal with 19 species. Although it has a worldwide monograph of the genus, the identification of species remains difficult and mainly based on the characteristics of the reproductive system. This work, which is a review of the genus  Digitaria in Senegal, is undertaken in order to search relevant characteristics on the vegetative system and to improve the identification of species. To do this, a detailed description of the various organs of the studied specimens is carried out using a binocular microscope. The results of the study show that the pubescence of the spikelet is an essential characteristic for the identification of species. Moreover, the relative lengths of the upper glume and lower lemma are very interesting for the discrimination of species closely related. However, the additional study of vegetative organs of the adult plant shows that some vegetative characteristics could contribute considerably to the improvement of the identification of species. It is the biological cycle, the pubescence of the ligule, the margin of the leaf blade, nodes and internodes of the thatch which are characteristics easier to observe. A key of determination based on vegetative and reproductive characteristics of species is thus worked out.© 2015 International Formulae Group. All rights reserved.Mots clés: Digitaria, Poaceae, review, key of determination, Senega

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Reversible Fragile Watermarking Scheme for Relational Database Based on Prediction-Error Expansion

The protection of database systems content using digital watermarking is nowadays an emerging research direction in information security. In the literature, many solutions have been proposed either for copyright protection and ownership proofing or integrity checking and tamper localization. Nevertheless, most of them are distortion embedding based as they introduce permanent errors into the cover data during the encoding process, which inevitably affect data quality and usability. Since such distortions are not tolerated in many applications, including banking, medical, and military data, reversible watermarking, primarily designed for multimedia content, has been extended to relational databases. In this article, we propose a novel prediction-error expansion based on reversible watermarking strategy, which not only detects and localizes malicious modifications but also recovers back the original data at watermark detection. The effectiveness of the proposed method is proved through rigorous theoretical analysis and detailed experiments

Flore adventices des bananeraies du Sud-Est Sénégal: Caractérisation de la flore et niveau d’infestation des espèces

In Senegal, bananas are mainly produced in the Southeastern areas. The production is low compared to the needs of the population because of several factors. This study aims to contribute to the knowledge of the floristic composition and diversity of weeds of banana in southern part of Senegal. In these assessed orchards, 76 weed species belonging to 56 genera and 18 families were recorded. Dicotyledons were the most important form representing 68 % of recorded species. Fabaceae, Poaceae and Malvaceae were the most represented botanical families with respectively 24.1 and 15.9% of flora. Spectrum analysis indicated that the flora is largely dominated annual, which includes 86% of the flora. The evaluation of the ecological value of species (IVI index) revealed that Commelina benghalensis, Cyperus rotundus, Euphorbia heterophylla are the most noxious species in banana plantations. In addition to their direct harmfulness, these three species, along with Croton hirtus, are recognized as alternative hosts for many pathogens, in particular the cucumber mosaic virus (CMV), the PVMY virus and the PVMV virus. However, the majority of species have a low frequency and coverage even if some of them, such as Croton hirtus, should be monitored in order to limit their expansion. In fact, they are invasive in some areas and/or crops and are resistant to most herbicides. Knowing these target species is essential before elaboration of any integrated weed management strategies for increasing banana yield under sudanian conditions of Southern-Eastern Senegal. Keywords : Banana plantation, Weeds, Noxious, IVI index, South-Eastern SenegalAu Sénégal, la banane est essentiellement produite dans les zones Sud-Est cependant cette production ne couvre même pas la moitié des besoins de consommations du pays qui continue à dépendre des importations à cause entre autres de l’absence de maîtrise des facteurs de production. Cette étude a été réalisée dans le but de caractériser la structure de la flore adventice de la banane en Haute Casamance et au Sénégal oriental. Des relevés ont été effectués dans des parcelles suivant la méthode des diagonales dans des quadrats de 50 cm de côté. Les résultats montrent que la flore adventice dans les bananeraies est composée de 76 espèces appartenant 56 genres et 18 familles. Cette flore est constituée à 86% d’espèces annuelles contre 14% d’espèces à caractères pérennes. Les familles des Poaceae, des Fabaceae et des Malvaceae sont les mieux représentées et cumulent près de la moitié des espèces recensées. L’évaluation de la valeur écologique des espèces (IVI index) a ressorti que Commelina benghalensis, Cyperus rotundus, Euphorbia heterophylla sont les espèces les plus infestantes dans les plantations de bananeraies. En plus de leur nuisibilité directe, ces trois espèces, en compagnie du Croton hirtus sont reconnues comme étant des hôtes alternatifs de nombreux pathogènes notamment le virus de la mosaïque du concombre (CMV), le virus du PVMY et le virus du PVMV. Cependant, la majorité des espèces ont une fréquence et un recouvrement faibles même si certaines d’entre-elles comme Croton hirtus sont à surveiller afin de limiter leur expansion. En effet, elles sont envahissantes dans certaines zones et/ou culture et résiste à la plupart des herbicides de post-levés actuellement vulgarisés. Cette étude préliminaire des adventices de la banane au Sénégal est utile et nécessaire pour planifier des approches de lutte intégrée des adventices prenant en compte le travail du sol, l’utilisation des herbicides, la fertilisation et les variétés. Mots-clés: Bananeraie, Adventices, Recouvrement, IVI index, Sud-Est Sénéga