Retama Monosperma Research Articles

Assessment of Acute Toxicity and Analgesic Activity of Organic and Aqueous Fractions from Retama Monosperma Stems

Assessment of Acute Toxicity and Analgesic Activity of Organic and Aqueous Fractions from Retama Monosperma Stems

Evaluation of the content of polyphenols, flavonoids and tannins, the antioxidant capacity, and the antimicrobial activity of different organic and aqueous fractions of stems of Retama monosperma

Retama monosperma is an endemic plant of the Mediterranean region that has been traditionally used in folk medicine to treat various ailments. It contains a variety of bioactive phytochemicals and exhibited several biological activities. This study aimed to assess the phytochemical screening, total phenolic, total flavonoid, and total tannin compounds, as well as the antioxidant capacity and antimicrobial activity. The phytochemical screening involved color reactions, characteristic reagents, and precipitation methods. Total phenolic, flavonoid, and tannin compounds were quantified using colorimetric methods across four fractions. Antioxidant capacity was assessed using 2,2-Diphenyl-1-picrylhydrazyl radical scavenging, ferric reducing antioxidant power, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging, and phosphomolebdenum assay. The antimicrobial activity was evaluated through disc diffusion method and the microdilution assay. Qualitative phytochemical tests revealed the presence of flavonoids, tannins, terpenoids, alkaloids, and sterols. Quantification of total phenolic, flavonoid, and tannin compounds confirmed the richness of polyphenolic compounds in all fractions. The antioxidant capacity measurements revealed that the ethanol fractions exhibited the highest antioxidant capacity in 2,2-Diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power assays, and phosphomolebdenum assay. Conversely, the aqueous fraction showed highest activity in the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assay. Regarding antimicrobial activity, the ethyl acetate fraction demonstrated superior efficacy against Staphylococcus aureus, and Bacillus cereus. These findings suggest that R. monosperma could serve as a valuable source of antioxidant and anti-infective phytocompounds.

Effect of application of urban sewage sludge as organic amendment on germination and growth of Retama monospermain Oran region of Algeria

Appropriate disposal of huge amount of sewage sludge generated in urban areas pose a serious threat to the environment. The urban wastewater treatment sludge has the potential as mineral organic amendment strategy in th fight against wind erosion through planting of Retama monosperma in Algeria. In the present study, the sewage sludge was sampled at the Bousfer –Oran wastewater treatment plant, and amended with different cultivation substrates. Further, its influence on the growth of young R. monosperma, plants, with an aim to replant them at sandy littoral deposits. The preliminary results of our work showed that the replanting of young Retamaplants in the substrate formed by a mixture of mud and limestone showed improved growth compared to the fourteen other substrates tested, from the point of view of structure, texture and fertilizing abilities.The sample of a mixture of clay and mud had a compact structure for the seeds to germinate. However, the growth of young plants transplanted into the latter was found to be improved giving an acceptable result considering the contributions of this organic amendment.

Phenolic Compounds from Moroccan <i>Retama monosperma</i> L. Boiss, <i>Berberis vulgaris</i> L. and <i>Ricinus communis</i> L.: Characterization, Antioxidant Activity and Performance Criteria of the Validated Method Using UHPLC/DAD/ESI-MS

Components of medicinal plants have many pharmacological activities, including antioxidant activity, playing an important role in limiting oxidative stress that can cause several damages. This paper characterizes polyphenols of Retama monosperma L., Berberis vulgaris L. and Ricinus communis L. plant extracts and evaluates their antioxidant activity by DPPH, conjugated diene and TBARS assay. To ensure the quality of analytical results, this paper presents performance criteria of the validated method using UHPLC/DAD/ESI-MS. Regarding method validation, the results confirm different used tests and evaluate detection and quantification limits. Concerning the characterization and study of antioxidant activity, realized testing showed that R. monosperma is rich in isoflavone, flavone and flavonol. For R. communis, we notice the presence of rutin as a major compound. Meanwhile, B. vulgaris contains significant amounts of gallic acid and p-coumaric acid. These plant extracts have high antioxidant activity due to the presence of phenolic compounds.

-

In Egypt, the taxonomic identity of the taxa under genus Retama Raf., 1838 (Fabaceae) is still unclear and its morphological resemblance precludes its identification. The current study aims to resolve the taxonomic identity of the species belonging to genus Retama in Egypt and clarify the morphological, molecular, and geographic distribution characterised each species. To achieve these goals, the fresh and herbarium Retama specimens were used for morphological investigations using 94 macro-morphological characters while the Inter Simple Sequence Repeats (ISSR) markers were used for the molecular identity. This revision revealed the identification of two distinct species namely: Retama raetam (Forsskk.) Webb. and Retama monosperma (L.) Boiss with five forms under R. raetam (Forms 2, 4, 6, 7, and 8). In addition to Form 5 from under R. monosperma; the morphological and molecular identities of forms showed variations in the meanwhile it's clustering were congruent. The geographic distribution of the Retama taxa in Egypt was elucidated. This study highlights the urgent need for Retama species conservation, due its vulnerability to climatic change.

A Comprehensive Review of the Pharmacological Properties and Bioactive Components of Retama monosperma.

Retama monosperma L. (Boiss.) or Genista monosperma L. (Lam.), known locally as "R'tam", is a spontaneous and annual herb that belongs to the Fabaceae family. It is native to the Mediterranean regions, specifically in the desert areas and across the Middle Atlas in Morocco. This plant has been extensively used in folk medicine and it is rich in bioactive compounds, including polyphenols, flavonoids, and alkaloids. Current research efforts are focusing on the development of novel natural drugs as alternatives to various organic and non-organic chemical products from Retama monosperma. In addition, extract, and isolated compounds obtained from different parts of the chosen plant have been described to exhibit multiple biological and pharmacological properties such as antioxidant, anti-aging, anti-inflammatory, antihypertensive, anti-helminthic, disinfectant, diuretic, and hypoglycemic effects. The plant-derived extract also acts as an antimicrobial agent, which is highly efficient in the treatment of bacterial, viral, and fungal infections. Its antiproliferative effects are associated with some mechanisms, such as the inhibition of cell cycle arrest and apoptosis. In light of these assessments, we critically highlight the beneficial effects of the flowers, stems, seeds extracts, and isolated compounds from R. monosperma (L.) Boiss in human health care, industrial, and other applications, as well as the possible ways to be employed as a potential natural source for future drug discovery.

Management of coastal dunes affected by shrub encroachment: are rabbits an ally or an enemy of restoration?

In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested.

Retama monosperma chemical profile, green synthesis of silver nanoparticles, and antimicrobial potential: a study supported by network pharmacology and molecular docking.

In this study, Retama monosperma extract (RME) was used for the green synthesis of silver nanoparticles (RME-AgNPs). RME's phenolic profile was identified by liquid chromatography coupled to mass spectroscopy (LC-ESI/MS/MS) technique. A tentative identification of 21 phenolic metabolites from the extract was performed. The produced RME-AgNPs showed UV absorbance at 443 nm. FTIR spectroscopy confirmed the presence of RME functional groups. In addition, XRD analysis confirmed the crystallography of RME-AgNPs via exhibiting peaks with 2θ values at 38.34°, 44.29°, and 64.65°. RME-AgNPs were spherical with particle sizes ranging from 9.87 to 21.16 nm, as determined by SEM and HR-TEM techniques. The zeta potential determined the particle's charge value as -15.25 mv. RME-AgNPs exhibited significantly higher antibacterial activity against Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, and Klebsiella pneumoniae) and Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) compared to RME. Moreover, the SEM images of green-synthesized nanoparticles revealed severe damage and deformation in the bacterial cell wall of the different strains subjected to the current investigation. The bioinformatics study identified 266 targets, among which only 41 targets were associated with bacterial infections. The PI3K-Akt and Relaxin signaling pathways were the top KEGG signaling pathways. Molecular docking was also performed for the 21 identified compounds at the TNF-α active site; kaempferol-3-O-robinoside-7-O-rhamnoside had a higher binding energy (-6.8084). The findings of this study warrant the use of green-synthesized AgNPs from Retama monosperma as potential antibacterial agents.

Anticancer Potential of Retama monosperma (L) Boiss in the Beni Mellal Khenifra Region

Anticancer Potential of Retama monosperma (L) Boiss in the Beni Mellal Khenifra Region

Biometrics analysis of the stem fibers of some local Algerian plant species

Studying the biometric characteristics of the stems of plant species has been of great interest to researchers in the wood and paper industry. The use of plant fibers has been widespread in the fields of composites, buildings, insulation, plastics and automobiles. The present study aimed to investigate the biometric characteristics of the stem fibers of local Algerian plant species, viz. Group 1 (Lygeum spartum and Stipa tenacissima), Group 2 (Linum usitatissimum in the greenhouse and Linum usitatissimum in natural conditions), Group 3 (Retama monosperma and Retama raetam) and Group 4 (Phoenix dactylifera and Ricinus communis). The extraction process was carried out using 1 M NaOH at 60 °C for 48 hours, and the fiber length was calculated for all the species using a micrometer. The fiber length of stems of all the species ranged from 0.36 to 5.18 mm. Then, the difference between each of the two species was approximated using Student's test. The results obtained showed that the t value ranged from 0.50 to 1.79 for Groups 4 and 1, respectively. There was no significant difference between them. These results suggest that these species are promising raw materials for paper production due to their adequate fibre length.

The use of medicinal plants against cancer: An ethnobotanical study in the Beni Mellal-Khenifra Region in Morocco

Although the use of medicinal plants is quite frequent in Morocco, no ethnobotanical study has targeted cancer patients in the Beni Mellal-Khenifra region. We aimed to measure the frequency of medicinal plants used by these patients in the Beni Mellal-Khenifra region and to make an inventory. An ethnobotanical survey was conducted with 530 cancer patients at the regional oncology center of Beni Mellal. We conducted a semi-structured interview using a questionnaire. Prevalence of use, relative frequency of citation (RFC), fidelity level (FL), and Informant Consensus Factor (ICF) were calculated. The prevalence of herbal use was 36.6%. The plant's relative frequency of citation ranged from 0.002 to 0.15. Fifty-four species belonging to 33 different botanical families were identified. The most common plants in use were: Marrubium vulgare L. (15%), Retama monosperma (L.) Boiss (11%), and Juniperus oxycedrus L. (10%). Six plants had an FL of 100% for breast cancer treatment, and the highest ICF for liver cancer treatment was 0.50. More than one-third of cancer patients in the region used herbal preparations. Indeed, informants did not agree on a particular type of cancer treatment. Further research is needed to assess the biological and toxicological aspects of Retama monosperma (L.) Boiss. And Juniperus oxycedrus L.

GC-MS and LC-QTOF-MS Phytochemical analysis, antiproliferative and antioxidant activities of stems extracts of Retama monosperma grown in Algeria

Retama species have been used in traditional Algerian medicine for a very long time. In this study, extracts of Algerian Retama monosperma stem were examined for their phytochemical composition by GC-MS and LCQTOF- MS analysis, then screened for their antioxidant activities and antiproliferative effects. Antioxidant activity has been evaluated in-depth using DPPH radical-scavenging activity test, ABTS•+ radical cation scavenging activity, total antioxidant activity and the β-carotene bleaching test. Antiproliferative activity was assessed by using four human cancer cell lines: A549, HEK-293, SKOV-3, HeLa and a non-malignant human cell line MRC-5. Interestingly, our results revealed a high amount of phenolic compounds and alkaloids in the methanolic extract. Indeed, the rates of total phenolics, flavonoids, flavonols and tannins were higher in the methanolic extract rather than aqueous extract. As a result, a higher antioxidant activity in all tests performed was registered in the methanolic extract. Remarkably, the methanolic extract exerted the highest antiproliferative activity against A549 and HeLa cells (IC50 = 85.42 ± 3.52 and 90.28 ± 6.75 μg/mL respectively) compared to aqueous extract. In a direct line, the chloroform, ethyl acetate and hexane fractions were able to inhibit cell growth in a dose-dependent manner and showed a significant antiproliferative activity in A549 cells. Moreover, a considerable activity on SKOV-3 (IC50 = 17.92 μg/mL) has been observed using the chloroform fraction. It should be noted that no cytotoxic effect has been detected by the extracts on the non-malignant human cell line MRC-5. In conclusion, these results underlined the antioxidant and antiproliferative potential of Algerian Retama monosperma.

Quantum and dynamic investigations of Complex iron- alkaloid-extract Cytisine derivatives of Retama monosperma (L.) Boiss. Seeds as eco-friendly inhibitors for Mild steel corrosion in 1M HCl

• The adsorption of Cytisine derivatives on the iron surface was modeled using DFT calculations as well as the dynamic Monte Carlo simulations. • DFT calculations were used to study the interaction of these inhibitors with iron Fe n (n=1-5). • MC and MD simulations were adopted to simulate the adsorption of Cytisine derivatives on the iron Fe (111) surface in vacuum as well as in acidic solution. • The radial distribution function (RDF), mean square displacement (MSD) and fractional free volume (FFV) were also studied using MD simulation. In this study, the adsorption of Cytisine derivatives as an eco-friendly inhibitor for mild steel corrosion [ 1 , 2 ] on the iron surface was modeled using density functional theory (DFT) calculations and the Monte Carlo (MC) as well as Molecular dynamics (MD) simulations to elucidate the interactions involved. Firstly, the interaction of these inhibitors with iron clusters Fe n (n=1-5) was studied by DFT as a representative example of a corrosion inhibition process. Moreover, structures, binding energies, partial atomic charge NBO and natural bond orbital analysis of the resulting complexes support the existence of considerable binding between these inhibitors and Fe n (n=1-5) clusters. Then, the dynamic Monte Carlo (MC) simulation was also adopted to simulate the adsorption of Cytisine derivatives on the iron Fe (111) surface in vacuum as well as in acidic solution containing 491 H 2 O, 4 hydronium ion H 3 O + and 5 chlorine ion Cl − . Besides, to advance the understanding of interactions between these molecules and iron surface, the radial distribution function (RDF), mean square displacement (MSD) and fractional free volume (FFV) were also studied in this paper. Our results of both the Fe n (n=1-4) clusters and the Fe (111) surface made it possible to show noticeable competitiveness between the three protonated inhibitors with a slight superiority for the n-CytN9H+ molecule. Furthermore, based on the diffusion coefficient we found that the three protonated inhibitors have a good capacity to slow down the movement of corrosive particles and consequently to inhibit the metallic substrate against corrosive electrolyte.

The Fodder Legume Chamaecytisus albidus Establishes Functional Symbiosis with Different Bradyrhizobial Symbiovars in Morocco.

In this work, we analyzed the symbiotic performance and diversity of rhizobial strains isolated from the endemic shrubby legume Chamaecytisus albidus grown in soils of three different agroforestry ecosystems representing arid and semi-arid forest areas in Morocco. The analysis of the rrs gene sequences from twenty-four representative strains selected after REP-PCR fingerprinting showed that all the strains belong to the genus Bradyrhizobium. Following multi-locus sequence analysis (MLSA) using the rrs, gyrB, recA, glnII, and rpoB housekeeping genes, five representative strains, CA20, CA61, CJ2, CB10, and CB61 were selected for further molecular studies. Phylogenetic analysis of the concatenated glnII, gyrB, recA, and rpoB genes showed that the strain CJ2 isolated from Sahel Doukkala soil is close to Bradyrhizobium canariense BTA-1T (96.95%); that strains CA20 and CA61 isolated from the Amhach site are more related to Bradyrhizobium valentinum LmjM3T, with 96.40 and 94.57% similarity values; and that the strains CB10 and CB60 isolated from soil in the Bounaga site are more related to Bradyrhizobium murdochi CNPSo 4020T and Bradyrhizobium. retamae Ro19T, with which they showed 95.45 and 97.34% similarity values, respectively. The phylogenetic analysis of the symbiotic genes showed that the strains belong to symbiovars lupini, genistearum, and retamae. All the five strains are able to nodulate Lupinus luteus, Retama monosperma, and Cytisus monspessilanus, but they do not nodulate Glycine max and Phaseolus vulgaris. The inoculation tests showed that the strains isolated from the 3 regions improve significantly the plant yield as compared to uninoculated plants. However, the strains of Bradyrhizobium sp. sv. retamae isolated from the site of Amhach were the most performing. The phenotypic analysis showed that the strains are able to use a wide range of carbohydrates and amino acids as sole carbon and nitrogen source. The strains isolated from the arid areas of Bounaga and Amhach were more tolerant to salinity and drought stress than strains isolated in the semi-arid area of Sahel Doukkala.

Effect of extracts and isolated compounds derived from Retama monosperma (L.) Boiss. on anti-aging gene expression in human keratinocytes and antioxidant activity

Ethnopharmacological relevanceMoroccan folk medicine treats skin cicatrization with Retama monosperma (L.) Boiss. locally named "Rtem", but the mechanism involved is still not well known. Traditional healers use the plant in small doses as an anthelmintic, disinfectant and an effective abortive. In addition, the cladodes powder mixed with honey is employed as purgative and vermifuge.Equally, the SIRT1 and SIRT3 genes activation and sirtuin proteins expression, which delay cellular senescence, participate in wound healing and skin regeneration especially, SIRT1 the most studied gene, leads to fast skin restoration and cicatrization. Aim of the studyIn this study, we evaluated the ability of the Retama monosperma (L.)Boiss. flowers and seeds extracts and the isolated compounds in augmenting the SIRT1 and SIRT3 gene expression in HaCaT cells and expressing the antioxidant activity. Materials and methodsWe examined for quantitative expression levels of SIRT1 and SIRT3 in HaCaT cell by qRT-PCR and the antioxidant activity by four tests (conjugated diene, TBARS assay, DPPH scavenging activity and H2O2 radical scavenging assay) of diethyl ether extract of flowers (DEF extract) and ethyl acetate extract of seeds (EAS extract) of R. monosperma(L.) Boiss. and the isolated compounds (quercetin, 6-methoxykaempferol, kaempferol and genistein). ResultsThe screening system by EGFP fluorescence revealed that all samples and resveratrol significantly increase SIRT1 and SIRT3 promoters activities in HaCaT cells with p< 0.05. Furthermore, EAS, quercetin, 6-methoxykaempferol and kaempferol increase significantly (p< 0.05) SIRT1 (3.43, 1.18, 2.62, and 1.72 expression quantity, respectively) and SIRT3 (16.27, 5.01, 3.01, and 6.18 expression quantity, respectively) in HaCaT cells. On the other hand, genistein has a moderate activity on SIRT1 and SIRT3 with 1.43 and 2.04 expression levels. For the antioxidant activity, the EAS and the pure compounds exhibited stronger antioxidant activity than BHT. While DEF and genistein have a moderate antioxidant activity when compared with BHT. ConclusionsIn this study, the expression levels of SIRT1 and SIRT3 in HaCaT cells increase in the presence of extracts of R. monosperma (L.) Boiss. and the pure compounds.

Impact of Mycorrhization on Phosphorus Utilization Efficiency of Acacia gummifera and Retama monosperma under Salt Stress

The impact of salt stress on the growth and phosphorus utilization efficiency (PUE) of two leguminous species: Retama monosperma and Acacia gummifera was studied. The effectiveness of arbuscular mycorrhizal fungi (AMF) to mitigate salt stress was furthermore assessed. Growth, N and P tissue concentrations, mycorrhizal root colonization frequency and intensity, and P utilization efficiency (PUE) in the absence or presence of AMF were evaluated under no salt (0 mM L−1) and three salt (NaCl) concentrations of (25, 50 and 100 mM L−1) using a natural sterilized soil. A significant difference in mycorrhizal colonization intensity, root-to-shoot ratio, P uptake, PUE, and N uptake was observed between the legume species. Salt stress inhibited the shoot and root growth, and reduced P and N uptake by the legume species. Mycorrhizal inoculation aided to mitigate the effects of salt stress with an average increase of shoot and root growth responses by 35% and 32% in the inoculated than in the non-inoculated A. gummifera treatments. The average shoot and root growth responses were 37% and 45% higher in the inoculated compared to the non-inoculated treatments of R. monosperma. Average mycorrhizal shoot and root P uptake responses were 66% and 68% under A. gummifera, and 40% and 95% under R. monosperma, respectively. Mycorrhizal inoculated treatments consistently maintained lower PUE in the roots. The results provide insights for further investigations on the AMF conferred mechanisms to salt stress tolerance response by A. gummifera and R. monosperma, to enable the development of effective technologies for sustainable afforestation and reforestation programs in the Atlantic coast of Morocco.

Characterization of Bradyrhizobium spp. Nodulating Lupinus cosentinii and L. luteus Microsymbionts in Morocco

In this work, we analyzed the diversity of the nodule-forming bacteria associated with Lupinus luteus and Lupinus cosentinii grown in the Maamora Cork oak forest acidic soils in Morocco. The phenotypic analysis showed the high diversity of the strains nodulating the two lupine's species. The strains were not tolerant to acidity or high alkalinity. They do not tolerate salinity or high temperatures either. The strains isolated from L. luteus were more tolerant to antibiotics and salinity than those isolated from L. cosentinii. The plant growth promoting (PGP) activities of our strains are modest, as among the 28 tested isolates, only six produced auxins, six produced siderophores, whereas three solubilized phosphates. Only two strains possess the three activities. The rrs gene sequences from eight representative strains selected following ARDRA and REP-PCR results revealed that they were members of the genus Bradyrhizobium. Six strains were then retained for further molecular analysis. The glnII, recA, gyrB, dnaK, and rpoB housekeeping gene sequence phylogeny showed that some strains were close to B. lupini LMG28514T whereas others may constitute new genospecies in the genus Bradyrhizobium. The strains were unable to nodulate Glycine max and Phaseolus vulgaris and effectively nodulated L. luteus, L. cosentinii, L. angustifolius, Chamaecytisus albidus, and Retama monosperma. The nodC and nodA symbiotic gene phylogenies showed that the strains are members of the genistearum symbiovar.

Heavy metals multi-tolerant Bradyrhizobium isolated from mercury mining region in Algeria

Heavy metals accumulation in the environment has led to a decrease in the capacity of ecosystems to sustain life as human, animal and plant health is threatened. To remedy this problem, rhizoremediation has been suggested as a solution. Legumes and rhizobia symbiotic association has captivated attention due to its involvement in the restoration of heavy-metal-contaminated sites. Thus, the aim of this study was to isolate and characterize the strains nodulating Calicotome spinosa plant that naturally occurred in two Algerian mercury mines. Fifty-four bacterial strains were isolated, then grouped into sixteen distinct BOX-PCR patterns and were genetically identified as belonging to the Bradyrhizobium genus. The studied strains were able to induce nodules on Retama monosperma, R. reatam, Lupinus albus, while no nodulation was observed in Glycine max, their symbiotic capacity was confirmed by amplifying the nodC gene. The phylogenetic analysis based on the nodC has grouped this Bradyrhizobium strains to either symbiovar genistearum or retamae. The isolates revealed diversity in terms of NaCl; pH tolerance, and phosphate solubilization. Production of siderophores was negative for these strains. All the isolated Bradyrhizobium were tolerant to both Zn and Pb in contrast they were sensitive to Cu and Cd. Interestingly, 43% of strains were tolerant to high Hg levels. Hence, some strains displayed multiple tolerances to heavy metals. Therefore, this is the first time we identify Bradyrhizobium strains originating from a North African mercury mine. This study could help to select mercury and other heavy metal-tolerant rhizobia showing an interesting potential to be used as inoculants to remediate the heavy metal soil accumulation.

The endemic Chamaecytisus albidus is nodulated by symbiovar genistearum of Bradyrhizobium in the Moroccan Maamora Forest

Out of 54 isolates from root nodules of the Moroccan-endemic Chamaecytisus albidus plants growing in soils from the Maamora cork oak forest, 44 isolates formed nodules when used to infect their original host plant. A phenotypic analysis showed the metabolic diversity of the strains that used different carbohydrates and amino acids as sole carbon and nitrogen sources. The isolates grew on media with pH values ranging from 6 to 8. However, they did not tolerate high temperatures or drought and they did not grow on media with salt concentrations higher than 85 mM. REP-PCR fingerprinting grouped the strains into 12 clusters, of which representative strains were selected for ARDRA and rrs analyses. The rrs gene sequence analysis indicated that all 12 strains were members of the genus Bradyrhizobium and their phylogeny showed that they were grouped into two different clusters. Two strains from each group were selected for multilocus sequence analysis (MLSA) using atpD, recA, gyrB and glnII housekeeping genes. The inferred phylogenetic trees confirmed that the strains clustered into two divergent clusters. Strains CM55 and CM57 were affiliated to the B. canariense/B. lupini group, whereas strains CM61 and CM64 were regrouped within the B. cytisi/B. rifense lineage. The analysis of the nodC symbiotic gene affiliated the strains to the symbiovar genistearum. The strains were also able to nodulate Retama monosperma, Lupinus luteus and Cytisus monspessulanus, but not Phaseolus vulgaris or Glycine max.Inoculation tests with C. albidus showed that some strains could be exploited as efficient inocula that could be used to improve plant growth in the Maamora forest.

Bradyrhizobium sp. sv. retamae nodulates Retama monosperma grown in a lead and zinc mine tailings in Eastern Morocco

The aim of this work was to characterize and identify some bacteria isolated from the root nodules of Retama monosperma grown in Sidi Boubker lead and zinc mine tailings. Very few root nodules were obtained on the root nodules of R. monosperma grown in these soils. The three bacteria isolated from the root nodules were tolerant in vitro to different concentrations of heavy metals, including lead and zinc. The rep-PCR experiments showed that the three isolates have different molecular fingerprints and were considered as three different strains. The analysis of their 16S rRNA gene sequences proved their affiliation to the genus Bradyrhizobium. The analysis and phylogeny of the housekeeping genes atpD, glnII, gyrB, recA, and rpoB confirmed that the closest species was B. valentinum with similarity percentages of 95.61 to 95.82%. The three isolates recovered from the root nodules were slow-growing rhizobia capable to renodulate their original host plant in the presence of Pb-acetate. They were able to nodulate R. sphaerocarpa and Lupinus luteus also but not Glycine max or Phaseolus vulgaris. The phylogeny of the nodA and nodC nodulation genes as well as the nifH gene of the three strains showed that they belong to the symbiovar retamae of the genus Bradyrhizobium. The three strains isolated could be considered for use as inoculum for Retama plants before use in phytoremediation experiments.