Phylogenomic Review of Root Nitrogen-Fixing Symbiont Population Nodulating Northwestern African Wild Legumes

The present review discusses the phylogenomic diversity of root nitrogen-fixing bacteria associated to wild legumes under North African soils. The genus Ensifer is a dominant rhizobium lineage nodulating the majority of the wild legumes, followed by the genus Rhizobium and Mesorhizobium. In addition, to the known rhizobial genera, two new Microvirga and Phyllobacterium genera were described as real nodulating and nitrogen-fixing microsymbiotes from Lupinus spp. The promising rhizobia related to nitrogen fixation efficiency in association with some legumes are shared. Phylogenetic studies are contributing greatly to our knowledge of relationships on both sides of the plant-bacteria nodulation symbiosis. Multiple origins of nodulation (perhaps even within the legume family) appear likely. However, all nodulating flowering plants are more closely related than previously suspected, suggesting that the predisposition to nodulate might have arisen only once. The origins of nodulation, and the extent to which developmental programs are conserved in nodules, remain unclear, but an improved understanding of the relationships between nodulin genes is providing some clues

Forage Potential of Non-Native Guinea Grass in North African Agroecosystems: Genetic, Agronomic, and Adaptive Traits

Guinea grass (Panicum maximum Jacq., renamed Megathyrsus maximus Jacq.) is a native forage plant in Africa of great economic value, but it was introduced in almost all tropical countries as a source of animal forage. Over the last decade, it was introduced in North arid regions of Africa (Morocco, Algeria, Tunisia, Libya, and Egypt) through authorized and unauthorized ways. It has two reproduction modes through sexual and apomictic ways. Besides its ability to provide high nutritive forage, guinea grass could affect the oases agroecosystems diversity due to its genetic aspects (apomixis and autotetraploidy) and eco-physiological traits (allelopathy effect and resistance to abiotic stress). That is why a review of genetic and eco-physiologic aspects of guinea grass is essential to investigate its potential introduction and management in new regions, particularly in arid and semiarid zones. In this paper, we review the most important traits of this plant that should be considered (polyploidy, apomixis, allelopathic effect, drought and salinity resistance, and invasion) for the potential success of guinea grass in integrated systems of forage/livestock

Evaluation of yield potential and some agronomic traits variability in Mediterranean alfalfa cultivars in the field under Tunisian conditions

Sixteen alfalfa populations, originating from the Mediterranean basin, were investigated under field conditions in Tunisia.Thisresearch aimed to evaluate the adaptation of cultivars to oases conditions of North Africa. The diversity among ecotypes wasstudied for potential yield and using some agronomic characters. The fall harvest had given the lower fresh yield in allpopulations and the greatest was recorded in the harvest of spring season. In addition, fresh yields were significantly different (p< 0.001) among populations, except at spring harvest. No significant differentiation was observed between populations in drymatter of both summer and spring harvest. Five agronomic characters showed significant differences between populations(p<0.001). Weeds and snail presence were negatively influenced to biomass production. However, covering and dormancy werepositively related to biomass production and they can be used as early production indicators. Three groups were identified bycluster analysis independently of geographical origin

Bioactive compounds, antioxidant and antimicrobial activities of extracts from different plant parts of two Ziziphus Mill. species.

Ziziphus lotus L. (Lam.) and Z. mauritiana Lam., as a widespread species in Tunisia, are well known for their medicinal and food uses. The aim of the present study was to screen the content of total polyphenols, flavonoids, and condensed tannins together with the radical scavenging capacity and the antimicrobial activity of leaves, fruits and seeds extracts of Z. lotus and Z. mauritiana from different localities. Results showed that leaves extracts presented the highest phenolic compounds content for both species. Furthermore, LC-ESI-MS analysis allowed the identification of 28 bioactive compounds regardless of species and organs, with the predominance of quinic acid and rutin. Leaves extract of Z. mauritiana possessed the highest total antioxidant capacity. The antimicrobial tests showed that leaves extracts of Z. mauritiana and Z. lotus from Oued Esseder exhibited the highest activity against four bacterial strains (Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and Escherichia coli). The main results showed that the studied species of Ziziphus genus are an excellent source of natural bioactive molecules that could be an interesting material for industrial and food purposes

Effect of date palm waste compost on forage alfalfa growth, yield, seed yield and minerals uptake

Abstract Purpose Date palm (Phoenix dactylifera L.) is one of the predominant fruit trees grown in oases ecosystems (Southern Mediterranean regions) and produces several wastes during practicing cultivation since fruit and bunch thinning is frequently applied. Yet, the valorization of date palm wastes as bioresources has received little attention. The main objective for the present research is to assess palm trees compost (P-compost) as organic fertilizer for alfalfa (Medicago sativa L.). Methods The experiment was carried out in an experimental field involving four replicates and three soil amendment treatments (1) control, conventional mineral fertilizer diammonium phosphate, (2) 30 t ha−1 of cow manure, and (3) 30 t ha−1 of palm tree compost (P-compost). Plots were planted on with alfalfa and the measurements of studied traits (growth, yield, seed yield and minerals uptake) were determined for two crop seasons (2010 and 2011). Results Compared with untreated soil, the palm compost application at 30 t ha−1 improved significantly both organic matter and water retention capacity of the soil and decreased the electrical conductivity (− 70%). Furthermore, palm compost supply significantly increased fresh biomass production of alfalfa by 21 and 28%, respectively, during the first and second seasons. Also, it enhanced the grain yield and growth rate (stem length and leafs expansion) of this species. At the first crop season, the palm compost application had a positive impact on minerals nutrition compared to the control treatment, with improving rates of + 32% for phosphorus, + 25% for potassium and + 6% for nitrogen. In addition, these contents were higher than in plants grown under cow manure amendment. However, at the second season, the palm compost improved only P and N contents. Conclusions This preliminary finding suggests that palm compost at moderate dose (30 t ha−1) could be highly beneficial for forage plant yield

Date seeds (Phoenix dactylifera): antioxidant potential and profile of free and bound polyphenols from different cultivars

2 Figuras.-- 5 TablasIn this study, the antioxidant activities and detailed phenolic profiling of extracts from seven cultivars of date seeds were investigated. Significant differences were detected among cultivars. Total phenolic content (TP) ranged between 135.9±12.1 and 284.86±21.9 mg GAE/g DM. The total flavonoid value varied between 34.20±0.34 and 94.46±1.04 mg RE/g DM. The condensed tannin ranged from 24.17±1.13 to 201.60±9.95 mg CTE/g DM. Phloroglucinolysis was used to depolymerize the bound polyphenols. Results show the presence of phenolic acids: Hydroxybenzoic acid, hydroxycinnamic acid, and a high amount of flavan-3ols (monomers, dimers, and trimers). Before depolymerization, the highest amount of total polyphenols was identified in Kenta (8.48 g/kg) and the lowest was detected in Hessa (4.74 g/kg). After depolymerization, the flavan-3-ols increased significantly, ranging between 46.91g/kg in Hessa and 72.38 g/kg in Deglet Nour, with a high degree of polymerization (DP) in all cultivars. It can be concluded that date seeds represent a good source of bioactive compounds.Spanish National Research Council (CSIC) State Agency. Grant Number: COOPB2060