Ultrastructure of interactions between Cassava and Xanthomonas campestris pv. manihotis : cytochemistry of cellulose and pectin degradation in a susceptible cultivar

A cytochemical investigation was carried out on the development of an aggressive strain of #Xanthomonas campestris pv. #manihotis, responsible for the cassava bacterial blight, to gain better insights into molecular and cellular mechanisms involved in leaf cell wall degradation by this pathogen. The use of anti-pectin monoclonal antibodies revealed that the plant middle lamellae were damaged during the infection process, from the epiphytic stage on the leaf surface to invasion of vascular bundles. In parallel, application of a beta-1,4-exoglucanase-gold probe to healthy and infected tissues indicated that primary and secondary cell walls were also altered. Quantitation of gold labeling confirmed that pectin was more severely degraded than cellulose. Accumulation of pectin-like compounds was also detected in occluded infected vessels. Bacterial-surrounding sheaths, which were routinely seen during pathogenesis early after leaf inoculation, had a dense or loosened fibrillar appearance and were differentiated from the pathogen cell wall. Close association occurred between extracellular fibrils and leaf cell walls, both at early and advanced stages of wall degradation. Bacterial extracellular sheaths were often seen deep in host cell walls, sometimes enclosing residual plant cell wall fragments. Our cytochemical data demonstrated that cell wall degradation of cassava by #Xanthomonas campestris pv. #manihotis plays an important role in host tissue colonization. It is also suggested that bacterial extracellular sheaths are involved in plant cell surface degradation. (Résumé d'auteur

Evaluation phytosanitaire de varietes locales et de nouvelles varietes de tomate (lycopersicum esculentum l.) au Togo

In the frame of the adaptability study of 20 tomato varieties to the West African ecological conditions; the phytosanitary behavior of these varieties was accessed in the comparison with 2 local varieties. Themajor pests identified on the tomato plants were: whitefly, broad mites, fruitworm, aphis and leafhopper. The evaluation of their effects showed that only the attack of fruitworm was higher on local varieties thanthe new varieties. Ten (10) new varieties have presented x level of resistance to viral disease as the local varieties on 1 to 5 notation scale. The assess of fungal diseases on plants showed that 16 new tomato varieties were susceptible to fusarium wilt than the local ones. Only one new variety was more resistant to early fungal blight caused by A. alternata than locales varieties. The assessment of bacterial diseases showed that 16 new varieties were as resistant as local varieties to bacterial spot on plants. All the varieties except one were resistant to bacterial wilt. In laboratory, in vitro isolation and characterization of the major pathogens from sampled disease symptoms allowed to purify and identify fungal isolates like F. oxysporum and A. alternata, then bacterial isolates like X. campestris pv. vesicatoria and P. syringae. The viral pathogens were not characterized

Un nouvel insecte ravageur majeur du sorgho, Poophilus costalis au Togo: degats et methodes de lutte

Le changement climatique est source de nouvelles conditions favorables à la prolifération des ravageurs. Depuis 2001, une espèce émergente, Poophilus costalis (Walker) (Hemiptera: Cercopidae), cause de sérieux dégâts aux cultures de sorgho au Togo. Des prospections ont été faites dans 75 champs de sorgho de la Région des Savanes au Togo en 2012 pour évaluer la densité de P. costalis et l’importance de ses dégâts. Par ailleurs, des bioessais ont été réalisés pour étudier la sensibilité du ravageur aux bioinsecticides Extrait de Graines de Neem (EGN), spinosad et abamectine et aux insecticides de synthèse cyperméthrine, carbofuran et chlorpyrifos éthyle. Les prospections ont montré que les attaques de P. costalis ont été fortes dans les préfectures de Tandjoaré, Cinkassé et Tône avec des densités respectives de 65, 56 et 39 individus sur 20 plants de sorgho. Les densités étaient faibles dans la préfecture de l’Oti (19 individus/20 plants) et modérées dans celle de Kpendjal (29 individus/20 plants). Comparés à l’Oti, Les indices de dégâts (ID) de P. costalis étaient forts (ID ≥ 2) à Tandjoaré, Cinkassé et Tône et modérés à Kpendjal (ID ≤ 2). Les bioessais ont montré que les insecticides EGN, chlorpyrifos éthyle et cyperméthrine ont été plus toxiques à P. costalis que spinosad, carbofuran et abamectine. Au vu de ces résultats, l’étude doit se poursuivre pour mettre au point une méthode de lutte intégrée incluant l’utilisation de l’EGN contre P. costalis. Mots clés: Changement climatique, Poophilus costalis, bioinsecticide, insecticide de synthèse, lutte intégré

Contraintes a la production de « Paala » (Solenostemon rotundifolius (Poir.) J.K.Morton) au Togo : Production constraints of “Paala” (Solenostemon rotundifolius (Poir.) J.K.Morton) in Togo

Paala [Solenostemon rotundifolius (Poir.) J.K.Morton, Lamiaceae] est une plante alimentaire mineure riche en nutriments et d’une grande importance socioéconomique, cultivée en Afrique tropicale et au Togo dans la région des Savanes. Sa culture connait un faible engouement en raison de plusieurs contraintes. Cette étude vise à identifier les différentes contraintes à la production de Paala au Togo afin d’améliorer sa productivité. Des focus group de taille entre 10 et 15 producteurs ont été organisés dans neuf villages de la partie nord-ouest de la région des Savanes pour recenser les principales contraintes biotiques, abiotiques et agronomiques. Il ressort que la totalité des producteurs font la monoculture de Paala sur une superficie moyenne de 555 ± 1,82 m² par ménage en comparaison avec les superficies emblavées pour toutes spéculations qui varient de trois à quatre hectares par ménage. Les insectes (80% de cas) et les souris (50% de cas) sont les principaux bioagresseurs évoqués par les producteurs. La principale maladie citée par 70% des producteurs est le jaunissement des feuilles. Pour leur gestion, la majorité des producteurs développent très peu de stratégies. Les contraintes abiotiques telles que la pauvreté des sols et l’irrégularité des pluies sont de l’ordre de 15%. Sur le plan agronomique, la conservation post-récolte des tubercules (60%), le sarclage/désherbage (30%) et les difficultés liées au labour/plantation (20%) des parcelles ont été citées par les producteurs. Cette étude a permis de recenser les principales contraintes liées à la culture de Paala dans l’optique d’améliorer sa production et la sécurité alimentaire au sein de la population Togolaise. Paala (Solenostemon rotundifolius (Poir.) J.K.Morton, Lamiaceae) is a minor nutrient-rich plant of great socio-economic importance, cultivated in tropical Africa and Togo in the Savannah region. Its cropping is weakened by some many constraints. This study aims to identify the different constraints to the production of Paala in Togo in order to improve its productivity.Focus groups of 10 to 15 producers were organized in nine villages in the northwest part of the Savannah region to identify the main biotic, abiotic andagronomic constraints. It appears that Paala is produced in monoculture system on an average area of 555 ± 1.82 m2 per household in comparison with the areas sown for all other crops whose areas vary from three to four hectares per household.Insects (80% of cases) and mice (50% of cases) are the main bioaggressors mentioned by producers. The main disease cited by 70% of producers is leaf yellowing. For their management, the majority of producers develop very few strategies. Abiotic constraints such as soil poverty and irregular rains are around 15%. Agronomically, post-harvest conservation of tubers (60%), weeding/weeding (30%) and difficulties related to tillage/planting (20%) were cited by producers.This study identified the main constraints related to Paala culture in order to improve its productivity and food security among the Togolese population

The impact of microfinance on energy access: a case study from peripheral districts of Lomé, Togo

International audienceThis study seeks to understand the impact of microfinance on energy access in the peripheral districts of Lomé in Togo. We use descriptive statistics, multiple regression, propensity score matching and treatment effect models, involving 639 microfinance client and non-client households for the analysis. Our results show that microfinance reduces energy vulnerability, with microfinance clients having higher energy poverty indices and energy expenditures than non-client households. Based on the impact of microfinance on energy poverty reduction, we argue that it is important for policymakers to implement strategies that promote and create greater access to microfinance, as this has the potential to alleviate energy poverty and improve access to good quality, modern energy services in Togo. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group