No abstract

Pterocarpus erinaceus Poir (Fabaceae) is an endemic, highly exploited and threatened plant species in arid and semi-arid zones of West Africa. This study was conducted at the sub-regional level across three countries, namely Burkina Faso, Niger and Togo. These countries represent a spatial ecological gradient of P. erinaceus distribution to collect information on population structure and silviculture operating standards that could guide the industry, ensure species regeneration and establish appropriate management strategies for the species. Data were collected in P. erinaceus populations by means of forest inventories. Results showed that the average tree density was 1.17 ± 0.75 trees/ha in the Sahelian zone, 49.20 ± 63.2 trees/ha in the Sudanian zone and 110.9 ± 1.15 trees/ha in the Guinean zone. The average stem diameter values were 26.63 ± 7.89 cm (Guinean zone), 29.02 ± 15.44 cm (Sudanian zone) and 49.63 ± 19.44 cm (Sahelian) with noticeable variability (CV = 53.6%). Significant differences for these parameters were noted between the zones (P b 0.001). The average total height in the populations of the Sudanian zone (9.51 ± 2.75 m) were significantly less (P b 0.001) than in the other two zones (10.18 ± 2.27 m for the Sahelian zone and 14.16 ± 2.88 m for the Guinean zone). The merchantable heights were between 4.08 ± 1.35 m (Sahelian zone) and 3.63 ± 2.63 m (Guinean zone) and varied significantly from one zone to another (P b 0.001). The distribution of trees in diameter classes varied depending on the climate zone: modal distribution with most classes ranging from 30-65 cm in the Sahelian zone and 15-45 cm in the Sudanian zone and an "L" model distribution in the Guinean zone (most classes ranging between 10 and 25 cm), while the distribution of height classes showed a modal form for all climate zones. Two minimum diameters of exploitation (MDEs) could be determined: 35 cm for the Guinean and Sudanian zones (P = 316.6% and P = 53.4%, respectively) and 65 cm for the Sahelian zone (P = 111.9%) for a rotation period estimated at 20 years for all the climate zones.

Reactive species causing oxidative stress are unavoidable by-products of various plant metabolic processes, such as photosynthesis, respiration or photorespiration. In leaves, flavonoids scavenge reactive species produced during photosynthesis and protect plant cells against deleterious oxidative damages. Their biosynthesis and accumulation are therefore under tight regulation at the cellular level. Glycosylation has emerged as an essential biochemical reaction in the homeostasis of various specialized metabolites such as flavonoids. This article provides a functional characterization of the Populus tremula x P. alba (poplar) UGT72A2 coding for a UDP-glycosyltransferase that is localized in the chloroplasts. Compared to the wild type, transgenic poplar lines with decreased expression of UGT72A2 are characterized by reduced growth and oxidative damages in leaves, as evidenced by necrosis, higher content of glutathione and lipid peroxidation products as well as diminished soluble peroxidase activity and NADPH to NADP+ ratio under standard growing conditions. They furthermore display lower pools of phenolics, anthocyanins and total flavonoids but higher proanthocyanidins content. Promoter analysis revealed the presence of cis-elements involved in photomorphogenesis, chloroplast biogenesis and flavonoid biosynthesis. UGT72A2 is regulated by the poplar MYB119, a transcription factor known to regulate the flavonoid biosynthesis pathway. Phylogenetic analysis and molecular docking suggest that UGT72A2 could glycosylate flavonoids, however the actual substrate(s) was(ere) not consistently evidenced with in vitro assays nor analyses of glycosylated products in leaves of transgenic poplar overexpressing or downregulated for UGT72A2. This article provides elements highlighting the importance of flavonoid glycosylation regarding protection against oxidative stress in poplar leaves and raises new questions about the link between this biochemical reaction and regulation of the redox homeostasis system.

pour le partenariat grâce auquel ce travail de terrain a été financé. RESUME L'article traite de la dynamique spatio-temporelle des unités d'occupation du sol de la Réserve Totale de Faune de Tamou (RTFT), zone périphérique du Parc national W Niger, entre 1975 et 2013. L'objectif de cette étude est d'évaluer les mutations spatio-temporelles que connaît la RTFT à la suite des variations climatiques et des pratiques diverses observées en matière de l'exploitation des ressources. La méthode de numérisation visuelle qui consiste à délimiter les différentes unités homogènes a été appliquée. Les données utilisées sont trois (3) images satellitaires dont Landsat MSS de 1975, Landsat ETM de 1989 et Landsat ETM d'octobre 2013. Entre 1975 et 2013, la superficie des différentes unités d'occupation des terres a subi des mutations substantielles qui se traduisent par une régression des aires des formations forestières, une augmentation de celles des cultures pluviales et l'apparition de deux nouvelles unités qui sont les koris et les sols nus. Ces changements ont été faibles

Diversity of carpophoric basidiomycete fungi infected with some species of Caesalpiniaceae from W Niger National Park (West Africa) ABSTRACT Objective: to contribute to the better understanding of macromycetes of Niger. It was conducted in the W National Park, which is located in the richest area in terms of biodiversity in the country. Methodologies and results: An inventory of fungi was conducted in four vegetation types: tree and shrub savanna with Afzelia africana and Combretum glutinosum (site 1); woodland with Isoberlinia doka and Anogeissus leiocarpa (Site 2); woodland with Isoberlinia doka and Berlinia grandiflora (site 3) and tree and shrub savanna with Burkea africana and Terminalia avicennioides (Site 4). In total, 56 species of macromycetes were identified at the study area belonging to 22 genera and 21 families. The ectomycorrhizal species amounted to 21, including 17 in site 1; 9 species in site 3; 3 in site 2 and one in site 4. This is due to the presence of some tree species from the Caesalpiniaceae family, namely Afzelia africana, Isoberlinia doka, Berlinia grandiflora and Burkea africana. Conclusion and application of results: Five ectomycorrhizal species (Amanita odorata, A. subviscosa, Lactarius gymnocarpoides, Russula albofloccosa and Phylloporus purpureus) were common tree and shrub savanna with A. africana and C. micranthum and woodland with I. doka and B. grandiflora.