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Decline of Senegalia senegal (Acacia senegal) in its natural range has been observed and attributed mainly to harsh environmental conditions such as frequent drought occurrences. The objective of this study is to assess the effect of water stress on growth, biomass allocation and photosynthetic capacity in Senegalia senegal seedlings. Seeds were collected from seven provenances in Senegal and grown under greenhouse conditions in a randomized complete block design with 5 replications. Seedlings were subjected to three cyclic droughts by watering them when average soil moisture content dropped to 4.7%, 2.7%, and 2.1% during the first, second, and third dry down cycles, respectively. With the exception of net photosynthetic rate, stomatal conductance and transpiration at the second and third dry down cycles, no drought by provenance interaction was found for any trait measured. Ngane provenance had a lower root/shoot ratio and allometric analysis revealed that Ngane allocated less biomass to roots than shoots. Ngane developed superior growth traits and biomass production, despite similar net photosynthetic rate with other provenances before treatments started. Overall, drought stress significantly reduced biomass, stem height, diameter and leaf gas exchange. Total biomass was reduced by 28.5%, whereas root/shoot ratio was increased by 25% compared to control. Significant interaction on leaf gas exchanges at the second and third dry down cycles reveals different sensitivity levels to drought among provenances with the Ranerou provenance exhibiting no decline in leaf gas exchange. No significant difference of stomatal limitation among genotypes was found, which is indicative of the complex process of photosynthesis and the need for extended times scales for measurements to better depict physiological sensitivity of Senegalia senegal to drought. [ABSTRACT FROM AUTHOR]

Aloe barbadensis, Capparis spinosa, and Senegalia senegal are popular in traditional medicine due to their therapeutic effects. We aimed to assess the neuropharmacological potential of their extracts, including the impact on pain-relief, anxiety, depression, muscle relaxation, and motor coordination. BALB/c mice were administered with standardized doses of A. barbadensis, C. spinosa, and S. senegal extracts, and their behavior was recorded through various neurobehavioral tests. The antioxidant potential of the extracts was also evaluated by DPPH assay. A differential response was observed among the three extracts for analgesic activity. A. barbadensis showed an increase in latency time after an increase in dose, while C. spinosa and S. senegal exhibited a biphasic response. A. barbadensis showed very good anxiolytic effects and best anti-depression effects. S. senegal exhibited the best antioxidant activity, followed by A. barbadensis and C. spinosa. This shows that these plants could counteract oxidative stress and protect neurons from potential damage caused by free radicals. The observed anxiolytic, muscle relaxant effects, and enhanced antioxidant potential of the selected plants in BALB/c mice, indicate their potential therapeutic value in neuroprotective strategies and the treatment of oxidative stress-related neurological disorders. However, further investigations into their underlying mechanisms and long-term safety profiles are suggested before considering their translation into clinical applications. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a Gram-positive bacterium that has reflected a noteworthy problem for public health. Nearly all Staphylococcus strains secrete lipase enzymes, which may cause damage to host tissues and deactivate host immune systems. This pathogen may colonize the skin and soft tissues. This study aimed to investigate the effectiveness of Arabic gum in inhibiting the lipolytic activity of pathogenic S. aureus commonly found in skin infections, through both lab-based and animal experiments. We obtained 300 specimens from individuals who met the clinical requirements for various skin diseases from four Egyptian hospitals: Al-Minshawi general hospital, Tanta University hospital, Kafr El-Zayat general hospital, and Mahalla general hospital, respectively. We determined the lipase activity for the S. aureus isolates and examined the effect of Arabic gum on mice against the lipase enzyme activity. Arabic gum treatment reduced the lipase activity at 1/2 MIC, 1/4 MIC, 1/8 MIC, and 1/16 MIC by 84.1%, 68.7%, 81.6%, and 68.6%, respectively. In male Sprague-Dawley mice, Arabic gum revealed a significant improvement in burn healing. All of the mouse groups used in the experiment showed better neovascularization and re-epithelialization in the histological tests on Arabic gum. Our results suggest that Arabic gum may help burn wounds heal faster by affecting tissue regeneration. We concluded that Arabic gum has promising antibacterial and wound-healing properties against S. aureus skin infections. [ABSTRACT FROM AUTHOR]

The effect of Gum Arabic (GA) on growth, carcass quality, blood parameters, gut morphometry, and organ histology of African catfish Clarias gariepinus was studied. Five isonitrogenous diets with inclusion levels of GA at 0 g/100 g (GA0; control), 5 g/100 g (GA5), 10 g/100 g (GA10), 15 g/100 g (GA15), and 20 g/100 g (GA20) were formulated in a 40% crude protein diet. Juveniles of C. gariepinus with average weight (7.35±0.48 g/fish) were stocked at 13 fish/25 L of water for 12 weeks in a completely randomized design and fed at 3% body weight daily. Growth indices showed GA10 improved the mean weight gain (69.88±8.89 g) and specific growth rate (2.76±0.14 %/day) while at (GA15); (GA20) growth was depressed. Carcass quality revealed dietary levels were superior to control with GA10 significantly different (p < 0.05) amongst treatments in protein and fat content. Hematological profile showed variations; erythrocyte indices compared to control, while plasma chemistry of aspartate aminotransferase, alkaline phosphatase, and alanine aminotransferase showed no difference (p > 0.05). Gut morphometrics varied with no particular pattern. At inclusion above GA5 the gill, liver, and kidney were affected histologically with no changes in the intestines of all treatments. Diet supplemented with gum arabic at 10 g/100 g improved indices of performance of C. gariepinus juveniles in this study. [ABSTRACT FROM AUTHOR]

Quaternary geographic range dynamics of savannah tree species are still not fully understood. The forest refuge hypothesis postulates that climatic and vegetational upheavals during the Pleistocene fragmented the previously continuous ranges of many species into isolated refuges that would have acted as shelters for rainforest taxa and allowed their survival through the Pleistocene cold stages. This hypothesis has recently been applied to studies of taxa in the African savannahs. We here test this hypothesis using the savannah tree species Senegalia senegal (L.) Britton., which is widely distributed across sub-Saharan Africa. Specifically, we ask the following questions: (i) Do we find evidence for savannah refugia during the last 130,000 before-present in sub-Saharan Africa? (ii) Would the climate in West Africa already have been suitable for S. senegal prior to the Last Glacial Maximum (LGM)? Using 1,132 occurrence records,we modeled the geographic distribution of S. senegal and projected the model into the past using climatic conditions from four time slices spanning the last 130,000 years bp. Our analyses show that the projected geographic extent of S. senegal was broader during the Last Interglacial, with a dramatic decline during the LGM and the subsequent recovery through the mid-Holocene to the present day. Our results indicate a range expansion at least from the mid-Holocene to the present and further show that S. senegal had similarly continuous distribution during the LGM as found today in sub-Saharan Africa. We also assessed the regional variation of environmental niche occupancy using a principal components analysis (PCA). The PCA reveals variation in the occupancy of environmental space across sub-Saharan Africa, a key indication of a wide ecological amplitude exhibited by the species. This study provides insights into the ancestral distribution and the temporal dynamics of a key savannah species that have shaped its current areas of occupancy.

Polyploidy is an important mechanism in angiosperm diversification and evolution. Polyploidization can lead to speciation when the chromosome doubling prevents interbreeding between coexisting cytotypes. In the case of Acacia senegal, different ploidy levels have been reported but the degree and impact of interploidy gene flow in natural populations is not yet resolved. This paper addresses the aspect by characterizing the genetic differentiation among ploidy levels and identifying prezygotic reproductive barriers against interploidy cross-pollination. We genotyped 293 individuals from 10 populations across Senegal using eight microsatellite markers. To study potential pre-zygotic reproductive barriers between diploids and polyploids, we compared the flower morphology and phenology between even-aged diploid and tetraploid trees from a common garden trial that consisted of four different populations originally selected in the natural distribution area of the species in Senegal. The analysis revealed variation among populations in the frequency of polyploids with common co-occurrence of the ploidy levels. The microsatellite markers revealed genetic differentiation between polyploid and diploid trees, and the floral studies identified differences that can act as prezygotic reproductive barriers: tetraploid trees had bigger polyads and stigma cup size compared to diploid trees. Also, polyploid trees on average flowered 9 days earlier than diploids although with overlaps in flowering time. Our results suggest that gene flow among cytotypes of A. senegal is limited and that interploidy pollination is likely to be restricted by differences in flower phenology and morphology. [ABSTRACT FROM AUTHOR]

Key message: Leaf morphology, total leaf nitrogen (N) content and carbon and nitrogen isotope ratios of Acacia senegal trees vary among ploidy levels and geographic origins. Leaf morphology was significantly correlated with carbon isotope composition (δ13C) among diploid trees, while a significant correlation was observed with nitrogen isotope composition (δ15N) among tetraploid trees. Leaf morphology and ploidy level can influence plants' ability to adapt to climatic conditions. Here we study Acacia senegal that has multiple ploidy levels and grows across a geographic range of mainly dry environments. We test if and how ploidy level and climate at the site of origin influence leaf shape and ratios of stable carbon and nitrogen isotopes of A. senegal. The study is based on leaves collected from 225 A. senegal trees representing 16 populations across the species range, grown in a common garden trial in Senegal. Leaf morphological parameters were measured, and ploidy level, total leaf nitrogen (N), carbon isotope ratios (δ13C) and nitrogen isotope ratios (δ15N) were determined. Three levels of ploidy were found, namely diploid, triploid and tetraploid, but at highly different frequencies among the 16 origins. Leaf morphology varied significantly among both geographic origins and ploidy levels, with especially triploid trees having distinct leaf shapes. Tetraploids displayed high δ13C and low δ15N values compared to diploids. For diploids, leaf length and number of leaflets were correlated with precipitation and latitude, respectively. Leaf morphology and isotopic discrimination in A. senegal vary according to ploidy level and geographic origin. Our analysis suggests that the differences likely reflect adaptation to different environments, but the patterns tend to differ between diploids and tetraploids. [ABSTRACT FROM AUTHOR]

The effects of temperature on the inhibitive effect of naturally occurring Acacia senegal gum exudate on the corrosion of mild steel in sulfuric acid was studied between 35 and 70 °C using electrochemical impedance spectroscopy and potentiodynamic polarization methods. Findings showed that Acacia senegal gum exudate decreases the corrosion rate of mild steel. The inhibition efficiency declined with raising temperature above 35 °C. The increase in the corrosion rate with increasing temperature was observed for both uninhibited and inhibited systems. Addition of halide ions to the Acacia senegal gum exudate solution enhanced the corrosion inhibition efficiency because of synergistic effects, achieving higher performance with iodide ions as compared to bromide ions. However, the synergistic effects declined above 35 °C up to 70 °C due to temperature effects. It has been observed that increasing temperature adversely affected inhibition efficiencies of both Acacia senegal gum exudate and the synergy between Acacia senegal gum exudate and halide ions. Corrosion rates of mild steel, inhibition efficiencies of Acacia senegal gum exudate and the synergistic effects of halide ions from polarization and impedance measurements were consistent. [ABSTRACT FROM AUTHOR]

• Key message: Variation among provenances of Acacia senegal (Senegalia senegal (L.) Britton) in their survival and growth in height and diameter at two sites in Senegal could be partly explained by the climate at their site of origin and also revealed genotype-by-environment interactions. Breeding programs and forest restoration projects should carefully select germplasm for optimal performance of this socioeconomically important tree species. • Context: Several studies have shown important differences in adaptive properties among provenances (origins) of African savanna tree species, but there is a lack of studies on how these differences are expressed in different environments and age and to what extent they reflect local adaptation. • Aims: This study investigates the survival and growth of trees from 15 African Acacia senegal (Senegalia senegal (L.) Britton) provenances tested in two environments and relates the differences among provenances to the climate at their site of origin and tree age. • Methods: The study is based on 14 years growth in a common garden trial at two sites (Bambey and Dahra, Senegal) that differ in water availability, followed up by later assessment after 23 years at one of the sites. • Results: The variation among provenances in survival, height, and diameter was significant, and differences could be partly explained by the climate at their site of origin. In general, provenances from dry sites survived better at both sites. However, we observed genotype-by-environmental interactions where provenances from dry sites on average performed relatively poorer in height and diameter at the wettest site (Bambey) compared to the drier site (Dahra), while the opposite was the case for provenances from wetter sites. • Conclusion: The results support that divergent selection creates and maintains local adaptation of Acacia senegal provenances in relation to growth (height and diameter) and survival in areas with different water availability. This has important implications for choice of appropriate planting material for tree planting and for conservation of genetic variation among natural populations, but also for prediction of the effects of climate change. [ABSTRACT FROM AUTHOR]

Correct timing of phenology is crucial for the survival and growth of species in arid areas with long dry seasons. Nevertheless, knowledge on genetic variation and adaptive patterns in phenology in deciduous African dryland species is limited. Here we study the variation in phenology of diploid and polypoid A. senegal trees from rangewide populations growing in a common garden trial in Senegal and test correlations between population phenology and climate at the site of origin. The leafing, flowering and fruiting phenology was monitored during 17 months and compared to detailed observations of the rainfall in the common garden during the period. We found that A. senegal trees in general started development of leaves prior to the beginning of the rainy season with flowering and fruiting initiation occurring during the rainy season. The results lead us to conclude that is was not the rain per se that initiated leaf development. We also conclude that phenology in A. senegal is under genetic control, because significant differences could be observed among populations and ploidy levels when grown at the same site. In general, early leaf flushing trees had a longer growing period and performed better in terms of growth at the tested site and the results thus support that leaf phenology influence fitness. We further found that differences among trees in phenology seem to be associated with differences in climate at their site of origin, because the timing of leaf development in the common garden and the timing of the rainy season at the site of origin was significantly correlated for the diploid trees (not for tetraploids). However, it was diploid trees from sites with a late arriving rainy season that developed leaves earliest in the year. The environmental cues that control leafing phenology and the associated physiological mechanisms therefore still need to be identified in order to understand how the variation among populations has evolved, its relationship to local adaptation and the implication for smart transfer of seed sources as mean to mitigate changing growing conditions related to global warming.

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Abstract Acacia senegal gum (Asen) is a natural exudate of Acacia trees species largely used in food as well as other industries. This natural product appears as a continuum of molecular species which shows diverse sugar and protein composition, molar masses and charge density. The presence of larger macromolecules, or aggregates, has been demonstrated to have a great influence on the Acacia gum characteristics. The present work is designed to recover and characterize one protein-rich fraction presenting a high aggregate content. With this fraction we will open the door to future works with the aim to acquire a deeper knowledge about the origin and the role of the aggregates from Asen gum. Our methodology is based on the well-known ion exchange chromatography, using DEAE Sephacel gel as stationary phase. We have separated Asen into two different fractions (fraction IEC-F1 and fraction IEC-F2), being both of them confirmed as arabinogalactan-proteins (AGP) by Yariv detection. Fraction IEC-F1 has been thoroughly characterized (sugar and amino acid composition, molar mass distribution, weight-average molar mass, number-average molar mass, polydispersity index, intrinsic viscosity, radius of gyration, Mark-Houwink-Sakurada analysis, hydrodynamic radius, partial specific volume and partial specific adiabatic compressibility). From amino acid data, we have estimated that fraction IEC-F1 theoretically corresponds to about 70% of HIC F3 and 30% of HIC F2, respectively the second and the third fractions separated by hydrophobic interaction chromatography (HIC) and largely described in literature. The obtained information indicates that fraction IEC-F1 appears as a fraction highly rich in aggregates. Graphical abstract Image Highlights • The presence of aggregates has a great influence on the Acacia gum characteristics. • By IEC, we recovered one protein-rich fraction, named IEC-F1. • IEC-F1 fraction has been thoroughly characterized. • IEC-F1 fraction appears as a fraction highly rich in aggregates. [ABSTRACT FROM AUTHOR]

Background Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N2 fixation, and to identify possible N and P ecosystem limitations. Methods Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0–10, 10–20,20–30 and 30–50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N2 fixation in relation to plantations age was assessed using δ15N isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0–10 cm) and increased with plantations age. Acacia foliage δ15N values were >6‰ and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0–10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of ‘nutrient uplift’ by the deeper roots. The high foliar δ15N values indicated that N2 fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N.

This study describes seed germination and micropropagation of Senegalia nigrescens, an economic, medicinal and nitrogen-fixing species of South Africa. Seeds of S. nigrescens were subjected to pre-sowing treatments including soaking in cold water for 24 h, sulphuric acid (H2SO4) or hydrochloric acid (HCl) for 4, 8 and 12 min and mechanically scarifying seeds before sowing on Petri plates with wet filter paper. Mechanically-scarified seeds were also sown aseptically on a filter paper bridge, plain agar, ½ or full strength Murashige and Skoog (MS) basal medium. Single nodal explants from MS-derived seedlings were grown on MS media supplemented with 0.0, 0.5, 1.0 and 2.0 mg L−1 of benzylaminopurine (BAP) or kinetin (KIN) and a combination of 0.5 mg L−1 of BAP and KIN to investigate shoot multiplication. No significant differences were observed in the number of shoots produced across all treatments. However, the treatment containing 1.0 mg L−1 KIN produced a significantly higher shoot length (14.17 ± 5.20 mm) than 0.5, 1.0 and 2.0 mg L−1 BAP (7.67 ± 3.87, 6.75 ± 2.93 and 8.70 ± 3.56 mm, respectively). The highest rooting rate (16.7%) was obtained on ¼ strength MS supplemented with either indole-3-acetic acid (IAA) or indole-3-butyric acid (IBA) at concentrations 1.0 and 0.5 mg L−1, respectively. Rooted plantlets were successfully acclimatised with a 66.7% survival rate. The findings from this study would be of great benefit for the commercial propagation of S. nigrescens. [ABSTRACT FROM AUTHOR]

The microstructure and surface properties of spin coated films were studied to determine the structuration of Acacia gum films depending on gum type and composition. The difference between A. seyal and A. senegal films was clearly evidenced by surface morphology (SEM and AFM) and through the contact angle measurement: A. senegal films having a smoother and more hydrophobic surface ( θ  = 62°) than A. seyal films ( θ  = 42°) characterized by aggregated structuration. The film hydrophobicity increased with glycerol addition for both gum films (A. senegal , θ  = 68° and A. seyal , θ  = 50°). This could be due to hydrogen-bonding between hydroxyl groups of plasticizer and polar groups of Acacia gums favoring their reduction on films surface. Both gum films behave as dual polar surface showing high disperse component of free energy compared to the polar component. Both gums showed strong affinity for apolar compounds ( θ < 20°). The overall results indicated that the structuration of films depended on the protein content and accessibility. Similar surface properties were found with self-supported films: A. seyal cast films being still more hydrophilic than A. senegal ones, demonstrating that the former provides a more favorable environment for water interaction than the latter. The specific interactions pointed for each gum films with water and apolar compounds were reflected in functionality such as water vapor permeability and efficiency to retain limonene and linalool. The knowledge of these properties is recommended to design specific coatings anticipating water loss of the coated product and to evaluate antimicrobial efficiency when active agents as aroma compounds are incorporated in the film. [ABSTRACT FROM AUTHOR]

Background: Over the last decades sub-Saharan Africa has experienced severe land degradation and food security challenges linked to loss of soil fertility and soil organic matter (SOM), recurrent drought and increasing population. Although primary production in drylands is strictly limited by water availability, nutrient deficiencies, particularly of nitrogen (N) and phosphorus (P), are also considered limiting factors for plant growth. It is known that SOM (often measured as soil organic carbon (SOC)) is a key indicator of soil fertility, therefore, management practices that increase SOM contents, such as increasing tree cover, can be expected to improve soil fertility. The objectives of this study were to investigate the effect of Acacia senegal (Senegalia senegal) trees on soil nitrogen, phosphorus and potassium (K) in relation to SOC, the potential of A. senegal for N2 fixation, and to identify possible N and P ecosystem limitations. Methods: Soil nutrient (total N, P, K and available P and exchangeable K) concentrations and stocks were determined for the 0-10, 10-20,20-30 and 30-50 cm layers of A. senegal plantations of varying age (ranging from 7 to 24-years-old) and adjacent grasslands (reference) at two sites in semi-arid areas of Sudan. At both sites, three plots were established in each grassland and plantation. The potential of A. senegal for N2 fixation in relation to plantations age was assessed using d15N isotopic abundances and nutrient limitations assessed using C:N:P stoichiometry. Results: Soil concentrations of all studied nutrients were relatively low but were significantly and directly correlated to SOC concentrations. SOC and nutrient concentrations were the highest in the topsoil (0-10 cm) and increased with plantations age. Acacia foliage δ15N values were >6? and varied little with plantations age. Soil C:N and C:P ratios did not differ between grassland and plantations and only 0-10 cm layer N:P ratios showed significant differences between grassland and plantations. Discussion: The results indicated that soil fertility in the Sahel region is strongly related to SOM contents and therefore highlighting the importance of trees in the landscape. The higher mineral nutrient concentrations in the topsoil of the plantations may be an indication of 'nutrient uplift' by the deeper roots. The high foliar δ15N values indicated that N2 fixation was not an important contributor to soil N contents in the plantations. The accretion of soil N cannot be explained by deposition but may be related to inputs of excreted N brought into the area annually by grazing and browsing animals. The soil C:N:P stoichiometry indicated that the plantations may be limited by P and the grasslands limited by N. [ABSTRACT FROM AUTHOR]

Climate change is predicted to impact species’ genetic diversity and distribution. We used Senegalia senegal (L.) Britton, an economically important species distributed in the Sudano-Sahelian savannah belt of West Africa, to investigate the impact of climate change on intraspecific genetic diversity and distribution. We used ten nuclear and two plastid microsatellite markers to assess genetic variation, population structure and differentiation across thirteen sites in West Africa. We projected suitable range, and potential impact of climate change on genetic diversity using a maximum entropy approach, under four different climate change scenarios. We found higher genetic and haplotype diversity at both nuclear and plastid markers than previously reported. Genetic differentiation was strong for chloroplast and moderate for the nuclear genome. Both genomes indicated three spatially structured genetic groups. The distribution of Senegalia senegal is strongly correlated with extractable nitrogen, coarse fragments, soil organic carbon stock, precipitation of warmest and coldest quarter and mean temperature of driest quarter. We predicted 40.96 to 6.34 per cent of the current distribution to favourably support the species’ ecological requirements under future climate scenarios. Our results suggest that climate change is going to affect the population genetic structure of Senegalia senegal, and that patterns of genetic diversity are going to influence the species’ adaptive response to climate change. Our study contributes to the growing evidence predicting the loss of economically relevant plants in West Africa in the next decades due to climate change. [ABSTRACT FROM AUTHOR]

The effects of Acacia senegal trees on soil moisture ( SM ) and hydraulic properties in relation to plantations age and associated changes in soil organic carbon (SOC) were investigated and compared to grasslands at two sites in Sudan. Soil hydraulic properties were computed using pedotransfer functions based on texture and SOC, and SM measured using TDR. The measured SM data was used to parametrize a simple daily water balance model in which Hortonian runoff was calculated using the SCS runoff curve number ( CN ) method and evapotranspiration calculated using crop coefficients, K c , adjusted to seasonal values using NDVI . Measured SM was higher in the grasslands than plantations, but increased with plantation age, reflecting a similar trend in plantation SOC and plant available water capacities. The modelling resulted in lower runoff from the plantations, increased infiltration, evapotranspiration, reduced drainage and lower SM , as shown by measurements. Greater SM contents in the grasslands were attributed to lower evapotranspiration and resulted in greater drainage fluxes compared to the plantations. The study highlighted the need for more empirical studies on the effect of tree density and cover on rainfall-runoff relationships, infiltration, evapotranspiration and drainage in drylands, especially those of the drier parts of semi-arid Africa. [ABSTRACT FROM AUTHOR]

Context Salinization causes the degradation of biological, chemical, and physical properties of soils. Salty soils reclamation can be achieved with organic amendments and afforestation with salt tolerant species. Aims The aim of the study was to assess in greenhouse conditions the effect of peanut shells on soil chemical characteristics and growth of multipurpose leguminous trees Senegalia senegal, Vachellia seyal, and Prosopis juliflora under salt-affected soils. Methods Seedlings were individually cultivated in plastic bags containing a mixture of non-saline and non-sterile soil and crushed peanut shells. Four doses of peanut shells (0, 4, 6, and 8 t ha−1) of 73-33 variety were tested. Salt stress was gradually applied after 1 month of cultivation at a rate of 43 mM NaCl per day until concentrations of 0, 86, 171, and 257 mM were reached. Seedlings growth, physiological responses, and soil characteristics were evaluated after 3 months of stress. Results Peanut shells application improved soil chemical properties (carbon, nitrogen, phosphorus contents, pH, total microbial activity, and cation-exchange capacity) and reduced soil salinity. They also increased height, collar diameter, shoots and root biomass, chlorophyll, and proline contents of seedlings. Conclusion The organic amendment with peanut shells improves soil fertility and tree growth under saline conditions. [ABSTRACT FROM AUTHOR]

Different studies reported variation on the physicochemicalproperties of Acacia Senegal var. Senegal gum Arabic exudates due to different factors including soil type, condition of the plant and climatic conditions. This work was performed on gum Arabic sampled from one area within the gum Arabic belt in Sudan. The aim was to study the physicochemical properties of this single sample. The data was analyzed comparatively to previously published records (1968-2016) from different areas in the gum belt, Sudan. The main physicochemical and functional features of the exudates gum Arabic were determined using different methods. The data obtained indicate the following values: moisture (14.5%), ash (2.5%), protein (2.2%), nitrogen (0.34%), viscosity (15.2mL/g) and pH (4.34). The fat content and nitrogen free extract were also analyzed and the values obtained were 0.05%, and 80.75%, respectively. The present data were compared with that published and is evidence that the properties: ash, protein and nitrogen were stable to a great extent regardless of factors such as area of collection and climatic condition within the gum belt. Moisture content showed less constancy and might be affected mainly by climatic conditions during exudation or storage type. Viscosity and pH revealed immense variations which can be attributed to variable preparation procedures followed such the concentration and temperature of gum solutions, and laboratory conditions. [ABSTRACT FROM AUTHOR]

Gum Arabic is believed to have many health benefits including prevention of gastrointestinal diseases. Prebiotic resist digestion in the upper gastrointestinal tract and allowed for stimulation of bacterial growth in the distal intestine and colon. The prebiotic properties of Acacia Senegal was studied using mixed cultures of human fecal bacteria from four lean individuals. The results obtained were compared with inulin as positive prebiotic control. Fermentation studies were carried out using anaerobic, pH-controlled faecal batch cultures, and the changes in the faecal microbial population were monitored at 0, 6, 12, 24 and 36h by fluorescent in situ hybridization (FISH). Quantitative FISH results revealed that Bifidobacteriumspp. Bacteroidacea spp. and Lactobacillus spp. were selectively increased (P<0.05) after the fermentation of Acacia Senegal by the fecal microbiota. Clostridium spp.,even have showed slight increase in fermentation of Acacia Senegaland inulin but was not significant. The stimulation of growth of probiotic bacteria was accompanied by a high production of acetate acid. The fermentation of Acacia Senegal may help to improve health through stimulation of bacteria growth which led to production of acetate. This study provides proof for the prebiotic effectiveness of Acacia Senegal, and the result showed that it might have a prolongedbifidogenic effect, thus could prevent certain types of diseases. [ABSTRACT FROM AUTHOR]

The tree Senegalia (Acacia) senegal is well adapted to soils of arid regions having a vital role in reforestation and increasing soil fertility through biological nitrogen fixation in addition to its utility as edible seeds and gum. Fifty-nine root nodule bacterial (RNB) strains were isolated; characterized at phenotypic and genotypic level; and host range was studied. The Senegalia-RNB strains were able to grow up to 3% NaCl and on a wide range of pH (5-11) with optimum growth at alkaline pH showing their adaptation to alkaline desert soil. The carbon utilization pattern of Senegalia-RNB strains was significantly different from existing closely related type strains of Ensifer. The PCR-RFLP (ARDRA) as well as RAPD patterns revealed considerable genetic diversity among the strains forming distinct genetic groups. The 16S rRNA phylogeny of selected six (AS11, AS18, AS27, AS34, AS50 and AS53) strains showed that they belong to fast growing species of Ensifer with few being similar to the previously described Ensifer strains from Vachellia jacquemontii and Vachellia leucophloea from Thar Desert of India. The symbiotic ( nifH and nodA) gene phylogeny showed incongruence with that of 16S rRNA gene (species) phylogeny suggesting HGT incidences under hot-arid and alkaline environment. The Senegalia-Ensifer strains possessing novel symbiotic genes could effectively cross-nodulate species of Vachellia ( V. jacquemontii, V. leucophloea and V. nilotica) but failed to nodulate the crop Vigna radiata. Multi locus sequence analysis (MLSA) is required to determine novelty of these Ensifer strains and more cross-inoculation studies will help in understanding their potential use as inoculums in nursery practices for reforestation program in arid and semi-arid regions. [ABSTRACT FROM AUTHOR]

Ancient Egyptian painted artworks are usually understudied from an analytical point of view, due to their extremely fragile nature. Attention typically focuses on pigments since identification is possible with non-invasive techniques, while limited information is available in the literature regarding the organic binding media. Here successful determination of the binder of a Roman Egyptian painted mummy shroud (2nd–3rd century A.D.) achieved through the application of enzymatic digestion followed by matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) is reported. The high specificity and sensitivity of this analytical strategy not only allowed the identification of the binding medium as a mixture of two different plant gums but also allowed the discrimination of the different species sources, even though the organic material was present in very small amounts and subject to degradation. The results of this study represent the first analytical identification of the earliest use of locust bean gum as a paint binder material as well as the use of gum arabic from an Acacia species different from the well-known Acacia senegal . The precise identification of the organic binder is a great step forward in the understanding of the painting materials and techniques used in Roman Egypt, of which little is known. The result of this research opens new avenues of art historical and conservation investigation into the specific plant sources and types selected by artists and it has implications for future conservation treatment options. [ABSTRACT FROM AUTHOR]

Multipurpose trees such as Senegalia senegal are widespread in arid and semi-arid lands that have natural or induced saline soils and poor soil fertility. Such environmental problems impact growth and have the potential to influence plant physiological adaptations. Identifying superior genotypes better adapted to these environmental stresses will be of great importance for tree selection for reclamation of degraded drylands. The main objective of this study was to examine the growth performance, and physiological and morphological adaptations to salinity, and fertility treatments of different Senegalia senegal families. We used five families (DB16, DB14, K4B19, K17B19, NB1) selected from 60 families of a Senegalia senegal progeny trial in Dahra, Senegal. Seedlings were grown under greenhouse conditions by watering all plants for three weeks and then stopping all watering for three more weeks. In a randomized complete block design, a two-level factorial combination was used for salinity (zero and 183.1 mM NaCl added) and fertility (zero and 100 kg/ha N-P-K added) treatments. A significant family × salt × fertilizer interaction was found for all biomass parameters (leaf dry matter, stem dry matter, root dry matter, and leaf area). The fertilizer application resulted in a significant increase of total biomass of all families, ranging from 63% to 237% for NB1 and K17B19, respectively. In contrast, salt only decreased total biomass of NB1 and K17B19 increased growth. Despite similar net photosynthetic rates before treatment started, fertilizer and salinity induced different effects between families. Prior to drought stress, fertilizer did not affect photosynthesis of DB16, while salt significantly decreased stomatal conductance of all families. DB16 and N1B1, despite significant differences of stomata size and density, significantly decreased transpiration, and thereby increased their intrinsic water use efficiency. Under drought, relative growth rate was significantly decreased. Given that genotype differences were found, these families and salinity and fertilizer treatments need to be explored in field trials. [ABSTRACT FROM AUTHOR]

The molecular composition of Acacia senegal and Acacia seyal gum exudate samples were studied using transmission electron microscopy. The molecules observed in both samples were found to have diameters of either ∼20 μm, ∼60 μm or ∼10 μm. These most likely represent the arabinogalactan (AG), arabinogalactan-protein (AGP) and glycoprotein (GP) molecules present in Acacia gum exudates. Micrographs obtained for gum solutions that had been left to stand for up to 5 days, indicated that molecular aggregation had occurred, this was particularly evident for the Acacia senegal sample. This aggregation process was attributed to intermolecular electrostatic interactions. The adsorbed layer thickness of the gums adsorbed onto polystyrene latex particles was determined using dynamic light scattering. For the Acacia senegal gum sample, it was found that the adsorbed layer thickness increased over time and after 14 days had a value of 61 nm. These findings are indicative of multilayer adsorption, through intermolecular electrostatic interaction. For the Acacia seyal gum sample the adsorbed layer thickness was only ∼3 nm and did not increase over time. Transmission electron microscopy revealed the presence of a distinct, thick adsorbed layer for the Acacia senegal gum and the presence of a much thinner, more diffuse layer for the Acacia seyal gum sample. Emulsification studies showed that the Acacia senegal gum was more effective at stabilising limonene oil-in-water emulsions than the Acacia seyal sample and that this was because markedly more Acacia senegal gum adsorbed at the oil-water interface compared to the Acacia seyal gum exudate. [ABSTRACT FROM AUTHOR]

The study examined the Effect of Weeding Status and Tapping Date on the yield of gum Arabic (Acacia Senegal) in Jigawa State, Nigeria. The said task has been accomplished by employing a two factorial experiment of complete randomized block design with three replicates which involves the weeding status and tapping dates conducted in 2014 season at two different locations; Kadoma and Kwanar duhuwa. The weeding status experiment comprises of three 100% weeded plots; and three Unwweded plots; while the tapping date investigation was tested at six levels (1st and 15th September, 1st and 5th October and 1st and 15th November). In each of these treatments three (3) trees were tapped making a total number of two hundred and sixteen trees in the two locations and one hundred and eight (108) trees at kadoma and Kwanar duhuwa respectively. The first picking of the gum yield tookplace 45day after tapping and each consecutive picking was collected after 15 days from the previous one. The gum from each picking was weighed after air drying with sensitive balance JY2002 model. SAS statistical package used for the data analysis thus DUNCAN multiple range test were employed in establishing the relationships between the variable investigated. Thus, the finding has revealed that gum Arabic tapping conducted on the 15th of October gave higher yield of gum Arabic when compared with the rest dates of tapping; the unweeded plots gave superior yield than the weeded plot. Therefore gum Arabic farmers were advised not to weed gum Arabic field when they are matured enough for harvest at the same time tapping should be carried out when the gum Arabic tree lost at least 50% of their leaves. [ABSTRACT FROM AUTHOR]

Acacia senegal is endemic to dry forest and woodland ecosystems of Sub-Saharan Africa and provides both ecological and socio-economic benefits. However, these ecosystems are threatened by escalating human disturbances and fragmentation. To investigate the human impacts on genetic diversity and structure of A. senegal, we studied genetic variability and differentiation of 330 individual trees from 11 natural A. senegal populations, grouped into lightly and heavily disturbed, using 12 polymorphic nuclear microsatellite markers. Gene diversity ( H ) ranged from H = 0.570 to H = 0.632. Significant differences ( P < 0.05) between the levels of disturbances are reported for mean gene diversity, number of alleles and allelic richness with lightly disturbed populations showing higher values. Overall, the indirect estimates of average outcrossing rates ranged from 0.794 (Kiserian) to 0.999 (Kampi ya Moto) with a mean of 0.997 suggesting a predominantly outcrossing species. There was no significant relationship ( P > 0.05) detected between genetic and geographic distances, showing lack of isolation by distance. Analysis of population structure using unweighted pair group method with arithmetic mean and Bayesian model suggests presence of three gene pools as most probable, although most individuals showed mixed ancestry. The diversity and genetic structure reported in this study revealed negative impacts of human disturbance on A. senegal within this ecosystem. We recommend in-situ conservation strategies to safeguard the woodland ecosystem from further deforestation. [ABSTRACT FROM AUTHOR]

Rhizobial inoculation has been widely used in controlled conditions as a substitute for chemical fertilizers to increase plants growth and productivity. However, very little is known about such effects on mature trees in natural habitats. In this study, we investigated the effect of rhizobial inoculation on soil total microbial biomass, mineral nitrogen content, potential CO2 respiration, fluorescein diacetate (FDA), acid phosphatase activities, and gum arabic production by 13-year-old Senegalia senegal (synonym: Acacia senegal) under natural conditions in the north part of Senegal during two consecutive years. Rhizobial inoculation was performed at the beginning of the rainy season (July) for both years with a cocktail of four strains (CIRADF 300, CIRADF 301, CIRADF 302, and CIRADF 303). Rhizospheric soils were collected in both dry and rainy seasons to a depth of 0-25 cm under uninoculated and inoculated trees. Trees were tapped in November (beginning of dry season) using traditional tools. Gum arabic was harvested every 15 days from December to March. The results obtained from both years demonstrated that rhizobial inoculation increased significantly the percentage of trees producing gum arabic, gum arabic production per tree, soil microbial biomass, FDA, and acid phosphatase activities. However, there was no significant effect on C mineralization and mineral nitrogen (N) content. Gum arabic production was positively correlated to rainfall, soil microbial biomass, and mineral nitrogen content. Our results showed a positive effect of rhizobial inoculation on soil microbial functioning and gum arabic production by mature S. senegal trees. These important findings deserve to be conducted in several contrasting sites in order to improve gum arabic production and contribute to increase rural population incomes. [ABSTRACT FROM AUTHOR]

The study is aimed to analyze and compare extraction methods of tannins from three common Acacia species of Sudan. The Acacia species selected were Acacia nilotica, Acacia seyal and Acacia senegal. Bark samples from bulk collections of the three Acacia species were extracted with water, 80% methanol and 70% acetone. Two sets of extraction were made, one by boiling and a second by shaking the samples in the respective solvents for eight hours at room temperature. Although the amount of material extracted by these two procedures did not differ greatly (P > 0.05), 70% acetone was a more efficient solvent than either water or 80% methanol. The tannins of mature fruits extract of Acacia nilotica were identified by using Thin Layer Chromatography (TLC), Ultraviolet and Infrared spectroscopy. Comparisons of absorption spectra and TLC of the reference tannins and some phenolics with that of Acacia nilotica extracts revealed the presence of both condensed and hydrolyzable tannins, since it consists of catechin, tannic and gallic acids. Catechin considered to be the phenolic precursor of condensed tannins. Hydrolysis of Acacia nilotica extract, tannic and gallic acids by butanolic-hydrochloric acid yielded gallic acid which is considered to be a chemical precursor of hydrolyzable tannins. [ABSTRACT FROM AUTHOR]

Polyploidy is a common phenomenon in the evolution of angiosperms. It has been suggested that polyploids manage harsh environments better than their diploid relatives but empirical data supporting this hypothesis are scarce, especially for trees. Using microsatellite markers and flow cytometry, we examine the frequency of polyploids and diploids in a progeny trial testing four different populations of Acacia senegal, a species native to sub-Saharan regions of Africa. We compare growth between cytotypes and test whether polyploid seedlings grow better than diploids. Our results show that polyploids coexist with diploids in highly variable proportions among populations in Senegal. Acacia senegal genotypes were predominantly diploid and tetraploid, but triploid, pentaploid, hexaploid, and octaploid forms were also found. We find that polyploids show faster growth than diploids under our test conditions: in an 18 years old field trial, polyploid superiority was estimated to be 17% in trunk diameter and 9% in height while in a growth chamber experiment, polyploids grew 28% taller, but only after being exposed to drought stress. The results suggest that polyploid A. senegal can have an adaptive advantage in some regions of Africa. [ABSTRACT FROM AUTHOR]

This study on predispersal seed predation of the leguminous species Vachellia abyssinica (Hochst. Ex. Benth.) Kyal & Boatwr., Senegalia senegal (L.) Britton, Vachellia seyal (Del.) P.J.H. Hurter, and Vachellia tortilis (Forssk.) Galasso & Banfi was conducted around Lake Langano and Menagesha Forest in Ethiopia to identify the associated seed predators and determine their impact on seed germination. Eight seed beetles Bruchidius albosparsus (Fåhraeus, 1839), B. aurivillii (Blanc, 1889), B. djemensis Decelle 1971, B. discoidalis (Fåhraeus, 1839), B. sinaitus (K. Daniel, 1907), B. silaceus (Fåhraeus, 1839), B. sp 411, B. simulans (Anton and Delobel, 2003), and one unidentified species of Cerambycidae were found associated with seeds of these Acacia species. These predators damaged less than 9% of seeds of these species, which exhibited lower germination. This study provides unrecorded lists of predispersal seed predators associated with seeds of Vachellia and Senegalia species in Ethiopia, and some associations are new. There is need to assess the distribution, abundance and effects of predispersal seed predators on other Vachellia, as well as other tree species. [ABSTRACT FROM AUTHOR]

The carbon (C) stocks of drylands, particularly in Africa, have become considerably depleted through land degradation leading to loss of soil fertility and water retention. Increasing tree cover is considered a practical means of increasing soil organic carbon (SOC) contents. However, few field studies have been carried out in the eastern part of the Sahel zone to test this hypothesis. In this study the C stocks in biomass and soil were determined in Acacia senegal plantations of varying age (7–24 years) and adjacent open grasslands in two locations in Sudan. The contribution of C 3 plants to SOC was estimated using a simple δ 13 C partitioning model. Total biomass C stocks increased with plantation age, reaching 1020 g m − 2 . While most of this increase was due to the trees, the C stock of the ground vegetation also increased with plantation age and was greater in the oldest plantations than in the open grassland. This finding supports the hypothesis that trees facilitate ground vegetation in semi-arid environments. Plantation SOC stocks (0–50 cm) ranged from 846 to 1250 g m − 2 , increased with age and were greater than open grassland values (867–950 g m − 2 ). The contribution of C 3 plants (trees and herbs) to plantation under canopies SOC stocks (0–10 cm) was 47.2% and 53.4% at the two sites. SOC sequestration rates up to 19 g C m − 2 yr − 1 were achieved in the oldest plantations at one of the sites. Our findings indicate that planting trees in drylands could considerably increase SOC stocks and efforts to plant Acacia trees in the Sahel should therefore be encouraged. [ABSTRACT FROM AUTHOR]

Generalizations about the drivers of tree demography in tropical savannas continue to prove difficult because of the complex and dynamic interactions involved, and because multi-year data sets spanning meaningful gradients in potential drivers are lacking., Overstorey trees play disproportionate roles in the long-term dynamics and functioning of savanna ecosystems. Understanding demographic patterns in these trees is complicated by their resprouting ability after being top-killed and few studies have attempted to separate top-kill from true mortality events., We examined the interactive effects of fire frequency, mean annual precipitation and elephant herbivory on overstorey (>2 m) tree mortality between 2009 and 2014 across 32 permanent vegetation plots in the Serengeti Ecosystem, Tanzania., Mean tree mortality over the study period was 0.28 ± 0.02 (0.07 year−1). Among trees that were top-killed (19.1% of all individuals), 31.2% resprouted. Mortality was driven largely by elephant herbivory, though mortality rates varied considerably across space and tree species. Fire frequency and mean annual rainfall were weak predictors of tree mortality. Over the 5 year period, chronic elephant herbivory (i.e. repeated through time) was a stronger predictor of tree mortality than maximum elephant herbivory, suggesting that repeated, low-intensity damage from elephants was more important to mortality than acute, but infrequent, damage., Elephants disproportionately damaged certain tree species relative to their availability on the landscape, and the tolerance to damage differed by species as well. Acacia senegal was strongly selected and appeared to have low tolerance to damage when it occurred, resulting in a mortality rate of 0.736 ± 0.052 (0.234 year−1) over the study period. Top-killing and resprouting rates varied across species, with Acacias generally having low resprout rates., Synthesis. Our study highlights the considerable role that chronic herbivory plays in structuring savanna tree populations, irrespective of prevailing fire and rainfall conditions, and provides important vegetative context to the dramatic recent declines and (in the case of Serengeti) increases in savanna elephant densities in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

BACKGROUND The search for natural, novel, high-quality, stable food ingredients is an ongoing practice in the food industry. Pulp of borojo ( Borojoa patinoi Cuatrecasas), which is a fruit of the Colombian Pacific region, can be separated into three phases: liquid ( LP), medium ( MP) and solid ( SP) phases. The objective of this work was to evaluate the effect of the three-phase composition and gum arabic on their glass transitions temperatures ( Tg). The best mixture, LP-MP, MP-SP and LP-SP and gum arabic ( GA) was identified by response surface methodology. RESULTS When adding GA to SP borojo phase in a 1:1 proportion, the resulting Tg of the mixture was 132.27 °C whereas Tg for GA and SP-phase were 154.89 °C and 79.86 °C respectively, which supported this combination as attractive from a processing perspective and supports an industrial advantage of using borojo as food ingredient. Phases were characterized by high-performance liquid chromatography, Fourier transform infrared spectroscopy, confocal laser scanning microscopy and mass spectrometry. Low molecular weight compounds such as fructose for MP lowered Tg whereas the presence of lignin increased Tg of the mixtures as with the SP. CONCLUSIONS The addition of GA significantly increased Tg of borojo phases so leading to propose them as novel food processing materials. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Aims: The focus of the study was to determine the symbiotic and growth response of three Senegalia Senegal (Syn. Acacia Senegal, gum arabic tree) provenances, namely Dahra (Senegal), Tera (Niger) and Makueni (Kenya) to inoculation with selected S. Senegal-nodulating rhizobia in soils from Dahra and Goudiry regions of Senegal, representing typical soil and enviromental conditions for establishing gum arabic production plantations. Methods: A greenhouse experiment was performed to evaluate the effect of 11 rhizobial strains on nodulation and growth of three S. Senegal provenances in two field soils, differing in nutrient status and indigenous rhizobia. After 4 months, plants were harvested for determination of nodulation, shoot and root dryweight. Results: Nodulation and growth of S. Senegal varied in relation to rhizobial strain, provenance, soil type, and their interactions. Generally, nodulation was higher in Dahra than Goudiry soils, while Makueni provenance was the most compatible host. Inoculation had a significant effect on all parameters measured in Dahra field soil. By contrast, inoculation had a significant effect on height (shoot length), and shoot, root and total dry matter but not on nodulation. In the two field soils, seed provenance effect was significant for all parameters measured. The interaction between inoculation and provenance showed a significant effect on all parameters measured except nodule number in Dahra field soil while in Goudiry, the interaction had a significant effect on seedling height and shoot, root, and total dry matter but this effect was not significant with nodulation parameters. Conclusions: S. Senegal is variable in its response to inoculation, it is therefore advantageous to select and match effective rhizobia-provenance symbionts for each site. [ABSTRACT FROM AUTHOR]

Acacia senegal is a multipurpose drought-tolerant tree or shrub legume, and is commonly used in agroforestry systems in sub-Saharan Africa for gum arabic production and soil fertility improvement. Despite its relatively wide distribution in Nigeria, there has not been exhaustive evaluation on the effects of the tree/shrub on soil physicochemical properties under its canopy for sustainable utilization of the tree. Accordingly, three sites in the semi-arid region of Nigeria representing three plantation ages of 7, 27 and 37 years old were selected for assessment. Soil samples were collected under tree canopies and were compared with the soils from the open canopies. Results indicated that there were significant differences in soil physicochemical properties among the three ages (P<0.05 and P< 0.01). Generally, soil nutrients under the canopies were higher than in the open canopiesirrespective of the age mainly due to effects of litter accumulation. The tree/shrubhas beneficial effects on soil nutrient status in their natural ecosystems and would most likely improve crop productivity in agroforestry systems such as alley cropping. The resultant improvement in soil nutrients status can increase herbage production in agricultural rangelands thus enhancing animal production in the study area. The tree/shrub growing under different soil types may have an effect on their gum Arabic production and quality. [ABSTRACT FROM AUTHOR]

Many studies that research bio-nanocomposites utilize techniques that involve the dispersion of strengthening components like silica, metal and metal oxides through a host biopolymer matrix. The biggest success factor for the bio-nanocomposite is having a smooth integration of organic and inorganic phases. This interattraction between the surfaces of inorganic particles and organic molecules are vital for good dispersion. In this study, a novel biodegradable antibacterial material was developed using gum arabic from Senegalia senegal (stabilizer), silica (structure reinforcer) and zero valent iron particles. Silica particles work to not only strengthen the mechanical properties of the Senegalia senegal but also prevent the accumulation of ZVI nanoparticles due to attraction between hydroxyl groups and FeO. The gum arabic/Fe–SiO 2 bio-nanocomposite showed effective antibacterial property against the Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli . Using Scanning electron microscopy, homogeneous dispersion and uniform particle size was viewed in the biopolymer. X-ray diffraction studies of iron particles organization in Senegalia senegal also showed that the main portion of iron was crystalline and in the form of FeO and Fe 0 . X-ray photoelectron spectroscopy was used to evaluate the chemical composition of the surface but no appreciable peak was measured for the iron before Ar etching. These results suggest that the surface of iron nanoparticles consist mainly of a layer of iron oxides in the form of FeO. Thermal gravimetric analysis was used to determine the thermal stability and absorbed moisture content. [ABSTRACT FROM AUTHOR]

The sulfur cathode in traditional lithium-sulfur batteries suffers from poor cyclability due to polysulfide shuttling effect as well as large volume change during charge/discharge processes. Gum arabic (GA), a low cost, nontoxic, and sustainable natural polymer from Acacia senegal, is adopted as a binder for the sulfur cathode to address these issues. The excellent mechanical properties of GA endow the cathode with high binding strength and suitable ductility to buffer volume change, while the functional groups chemically and physically confine sulfur species within the cathode to inhibit the shuttling effect of polysulfides. Additionally, GA shifts the electrode fabrication process from the organic solvent process to an aqueous process, eliminates the use of toxic organic solvents, and achieves uniformly distributed electrode with lower impedance. A remarkable cycling performance, i.e., 841 mAh g−1 at low current rate of C/5, is achieved throughout 500 cycles due to the bifunctions of the GA binder. [ABSTRACT FROM AUTHOR]

Multipurpose trees such as Senegalia senegal are widespread in arid and semi-arid lands that have natural or induced saline soils and poor soil fertility. Such environmental problems impact growth and have the potential to influence plant physiological adaptations. Identifying superior genotypes better adapted to these environmental stresses will be of great importance for tree selection for reclamation of degraded drylands. The main objective of this study was to examine the growth performance, and physiological and morphological adaptations to salinity, and fertility treatments of different Senegalia senegal families. We used five families (DB16, DB14, K4B19, K17B19, NB1) selected from 60 families of a Senegalia senegal progeny trial in Dahra, Senegal. Seedlings were grown under greenhouse conditions by watering all plants for three weeks and then stopping all watering for three more weeks. In a randomized complete block design, a two-level factorial combination was used for salinity (zero and 183.1 mM NaCl added) and fertility (zero and 100 kg/ha N-P-K added) treatments. A significant family × salt × fertilizer interaction was found for all biomass parameters (leaf dry matter, stem dry matter, root dry matter, and leaf area). The fertilizer application resulted in a significant increase of total biomass of all families, ranging from 63% to 237% for NB1 and K17B19, respectively. In contrast, salt only decreased total biomass of NB1 and K17B19 increased growth. Despite similar net photosynthetic rates before treatment started, fertilizer and salinity induced different effects between families. Prior to drought stress, fertilizer did not affect photosynthesis of DB16, while salt significantly decreased stomatal conductance of all families. DB16 and N1B1, despite significant differences of stomata size and density, significantly decreased transpiration, and thereby increased their intrinsic water use efficiency. Under drought, relative growth rate was significantly decreased. Given that genotype differences were found, these families and salinity and fertilizer treatments need to be explored in field trials.

The chemical and physicochemical characteristics of gum exudate samples harvested from mature trees of Acacia senegal at two new specific ecolocations in Nigeria, have been investigated together with gum samples harvested from A. senegal and A. seyal originating from Sudan. The monosaccharide sugar compositions for the A. senegal gum samples were found to be similar, but the protein contents for the Nigerian samples were significantly higher than recorded for the Sudanese sample. Gel Permeation Chromatography coupled to light scattering, refractive index and U.V. detectors, has shown the presence of arabinogalactan, arabinogalactan–protein and glycoprotein fractions within the A. senegal gums and has also shown the presence of an additional small proportion of very low molar mass proteinaceous material all the samples which has previously been ignored. The plot of radius of gyration, R g , as a function of elution volume showed a discontinuity for one of the Nigerian samples and for the A. seyal gum sample at elution volumes corresponding to the AGP component suggesting a different molecular structure. Plots of Mw–v–R g confirmed that the molecules had a compact structure. The hydrodynamic size of the molecules was followed using dynamic light scattering as a function of time and it was found that molecular association occurred in solution. The extent of association increased as the protein content in the sample increased and was inhibited in the presence of electrolyte, it was concluded that association was due to electrostatic interaction between the protein moieties and glucuronic acid groups on individual macromolecules. [ABSTRACT FROM AUTHOR]

Acacia gum is a natural arabinogalactan-protein type polysaccharide widely used in industrial applications. The two varieties of Acacia gum, A. senegal and A. seyal , are hyperbranched polysaccharides rich in arabinose and galactose (PRAG) mainly formed by chains of 3,6-linked β-D-Gal p substituted in position 6 by side chains of 3-linked α-L-Ara f . Beyond this common structure, A. senegal presented the highest degree of branching (78.2% vs. 59.2%) with more branched galactopyranoses, shorter arabinosyl side branches, and more rhamnopyranoses in terminal position. Circular dichroism experiments evidenced that both Acacia gums were partially structured into polyproline type II helices but in a lesser extent for A. senegal gum, suggesting its less structured organisation. The fingerprint of both Acacia gums and their spectral differences determined by FTIR spectroscopy were described. Analysis of HPSEC-MALLS data suggested that macromolecules of both Acacia gums adopted an ellipsoid-like conformation in solution. The average molecular weight of A. seyal macromolecules was larger than that of A. senegal ones (8.2 × 10 5 g mol −1 vs. 6.8 × 10 5 g mol −1 ). Nevertheless, A. seyal macromolecules appeared more compact and less viscous (R g : 17.1 nm; [η]: 16.5 mL g −1 ) than A. senegal ones (R g : 30.8 nm; [η]: 22.8 mL g −1 ). The most compact structure of A. seyal gum can be partly explained by the lowest concentration of charged sugars that induces less electrostatic repulsion, and the highest content of long arabinose side chains that may self-organize and interact between them (e.g. hydrogen bonding, steric effect, etc.). For both Acacia gums, the anisotropy of macromolecules increased with the molecular weight, however, A. senegal macromolecules were the most anisotropic ones. [ABSTRACT FROM AUTHOR]

Conventionally, local seed sources are normally believed to perform better than introduced materials. However, studies show possibility of contrary results with many species such as Acacia senegal. The species is an economically and ecologically important tree of arid and semi-arid lands of sub-Saharan Africa. It produces gum arabic, used in land reclamation and agroforestry production. The species is however underutilized in Kenya due to lack of information on growth performance of different seed sources. Glasshouse provenance trial using seeds and soils from seven provenances in Kenya were used to evaluate interactions between seed sources and soils on growth and biomass. Seedling growth was assessed for 12 weeks in a randomized complete block design. Seed length, width, thickness and weight were measured. Seedlings height, root collar diameter, root dry weight, shoot dry weight and biomass were assessed and data subjected to univariate and multivariate analyses. No significant interaction between seed provenance and soils were evident; however, some provenances performed better across all the soils. Significant heritability and relationship between growth and environmental factors are reported. Overall, Ntumburi and Ngarendare provenances showed superior growth and plasticity. These provenances can be used tentatively as seed sources; however, field trials are recommended. [ABSTRACT FROM AUTHOR]

Gum arabic is an important international commodity produced by trees of Acacia senegal across Sahelian Africa, but documented results of breeding activities are limited. The objective of this study was to provide reliable estimates of quantitative genetic parameters in order to shed light on the breeding potential for improvement of gum yield and quality. For this purpose, we measured growth on 617 off- spring from 60 open-pollinated trees after 18 years, and gum yield and quality based on two seasons, 18 and 19 years after establishment. Genotyping with eight microsatellite markers revealed that progenies consisted of both diploid and polyploid trees, and growth, gum yield, and gum quality varied substantially among ploidy level, populations, and progenies. Analysis of molecular variance and estimates of outcrossing rate supported that trees within open-pollinated families of diploids were half sibs, while the open-pollinated families of polyploids showed low variation within families. The difference in sibling relationship observed between ploidy levels complicated estimation of genetic parameters. However, based on the diploid trees, we conclude that heritability in gum arabic production is low to high with presence of high levels of additive genetic variation, although the genetic parameters could only be estimated with fairly high standard error. The findings suggest that improvement through breeding can increase the productivity of A. senegal substantially. However, the results also stress the importance of testing ploidy levels of selected material and use of genetic markers to qualify the assumptions in the quantitative genetic analysis. [ABSTRACT FROM AUTHOR]

Gum arabic is the complex exudate of theAcacia senegalandAcacia seyaltree. This dried sap with immense commercial value is a global commodity, generally harvested in Africa and Western Asia. Non-digestibility, low solution viscosity, and generally recognized as safe status renders its popularity in the food industries. For its desirable emulsifying, stabilizing, binding, and shelf-life enhancing properties, it has found application in many foods. Current literature suggests its cardio-, reno-, gut-, and dental- protective, satiety-inducing, antimicrobial, anti-inflammatory, and anticoagulant implications. Its foray into drug delivery, sensor, tumor imaging, and nano-technology has met with appreciable success, fueling further investigation into its unexplored functionality. The objective of this review was to highlight the recently-unraveled pharmacological potential of this gum with an aim to provide holistic information on its wide spectrum of utility and prospects. [ABSTRACT FROM AUTHOR]

Acacia senegal and Acacia seyal are small, deciduous legume trees, most highly valued for nitrogen fixation and for the production of gum arabic, a commodity of international trade since ancient times. Symbiotic nitrogen fixation by legumes represents the main natural input of atmospheric N into ecosystems which may ultimately benefit all organisms. We analyzed the nod and nif symbiotic genes and symbiotic properties of root-nodulating bacteria isolated from A. senegal and A. seyal in Senegal. The symbiotic genes of rhizobial strains from the two Acacia species were closed to those of Mesorhizobium plurifarium and grouped separately in the phylogenetic trees. Phylogeny of rhizobial nitrogen fixation gene nifH was similar to those of nodulation genes ( nodA and nodC). All A. senegal rhizobial strains showed identical nodA, nodC, and nifH gene sequences. By contrast, A. seyal rhizobial strains exhibited different symbiotic gene sequences. Efficiency tests demonstrated that inoculation of both Acacia species significantly affected nodulation, total dry weight, acetylene reduction activity (ARA), and specific acetylene reduction activity (SARA) of plants. However, these cross-inoculation tests did not show any specificity of Mesorhizobium strains toward a given Acacia host species in terms of infectivity and efficiency as stated by principal component analysis (PCA). This study demonstrates that large-scale inoculation of A. senegal and A. seyal in the framework of reafforestation programs requires a preliminary step of rhizobial strain selection for both Acacia species. [ABSTRACT FROM AUTHOR]

Gum Arabic (GA), a food hydrocolloid is a natural composite obtained from the stems and branches of Acacia Senegal and Acacia Seyal trees. GA structure is made up of highly branched arabinogalactan polysaccharides. Steady-state absorption, fluorescence, and time-resolved fluorescence spectral studies of acid hydrolyzed GA solutions were carried out at various pH conditions. The fluorescence in GA is predominantly attributed to the presence of tyrosine and phenylalanine amino acids. The presence of multi-emissive peaks at different pH condition is attributed to the exposure of the fluorescing amino acids to the aqueous phase, which contains several sugar units, hydrophilic and hydrophobic moieties. Time-resolved fluorescence studies of GA exhibits a multi-exponential decay with different fluorescence lifetime of varying amplitude which confirms that tyrosine is confined to a heterogeneous microenvironment. The existence of multi-emissive peaks with large variation in the fluorescence intensities were established by 3D emission contour spectral studies. The probable location of the fluorophore in a heterogeneous environment was further ascertained by constructing a time-resolved emission spectrum (TRES) and time-resolved area normalized emission spectrum (TRANES) plots. Fluorescence spectral technique is used as an analytical tool in understanding the photophysical properties of a water soluble complex food hydrocolloid containing an intrinsic fluorophore located in a multiple environment is illustrated. [ABSTRACT FROM AUTHOR]

Senegalia ebingeri Seigler (Fabaceae, Mimosoideae) is described from Cusco and is known from Apurimac, Ayacucho, and Puno in southern Peru. The new species is illustrated and compared to its probable nearest relatives S. tenuifolia (L.) Britton & Rose, S. riparia (Kunth) Britton & Rose, and S. tubulifera (Benth.) Seigler & Ebinger. [ABSTRACT FROM AUTHOR]