The effect of salinity gradient and heavy metal pollution on arbuscular mycorrhizal fungal community structure in some Algerian wetlands

Algerian natural wetlands suffer from anthropogenic disturbances due to industrial development and urbanization. This study was designed to draw attention to arbuscular mycorrhizal fungi (AMF) distribution and community assemblages following heavy metal and salinity concentrations in two wetlands subjected to domestic and industrial effluents. Rhizospheric soil and roots of 18 plant species were collected in two wetlands along a decreasing salinity gradient. The results showed that 72.72% of plant species exhibit an association within arbuscular mycorrhizas (AM), and 36.36% a dual association between AM and dark septate endophytes (DSE). A total of 33 AMF morphospecies were distinguished on the basis of morphological criteria dominated by taxa belonging to Glomeraceae and Acaulosporaceae. Soil contamination was investigated by determining metallic trace elements (MTE) (Cd, Cu, Ni, Pb, Cr and Zn) using an atomic absorption spectrophotometer. Values of the pollution index revealed wetlands that were particularly polluted by lead. Two˗way ANOVA showed significant variations in metal content among sampling locations and transects. Principal component analysis showed that species richness, and mycorrhizal frequency were slightly affected by MTE. This opens possibilities for their utilization in polluted soil remediation

Growth and mycorrhizal responses to cadmium stress in some halophytic plants

2Abdelhamid Ibn Badis University, Mostaganem, Algeria. The phytoremedial potential of three halophytes and the role of arbuscular mycorrhizal fungi (AMF) isolated from heavy metal contaminated soil under cadmium stress were studied. The plants were treated with different Cd concentrations (0, 50, 200, and 400 µM) with and without AMF inoculation. On the plant growth, AMF inoculation to all species resulted in increased biomass, shoots and roots length, and leave number compared to control (non-inoculated) plants, especially in Limbarda crithmoides, where no mortality was detected neither in controls nor inoculants. Furthermore, L. crithmoides and Atriplex canescens recorded higher values of relative mycorrhizal dependency and water content. The arbuscular mycorrhizal association was observed in all host plants and was not affected by cadmium. Our results indicate that studied halophytes can tolerate high Cd concentrations due to the support of AMF, particularly in Atriplex halimus association with AMF in pot experiment which was recorded for the first time

Diversity of Algerian basidiomycetes, morphological, macrochemical and genotypic characterisation

A collection of 16 basidiomycetes was carried out in northwestern Algeria. During the harvest, the average temperature of the sites was between 11.2 to 19.3 °C with an average humidity of 67 to 90%.  The dominant plants observed at the sampling sites are pine, oak and false pepper. The collected mushrooms were identified by their macroscopic, microscopic (light microscope and scanning electron microscope) and macrochemical characteristics using chemical reagents to distinguish among the different species. Of the 16 fungi, a genotypic identification was made using the tools of molecular biology and bioinformatics analysis.  The results of the phenotypic analysis showed that the fungi in question were: Lactarius zonarioides, Amanita proxima, A. virosa, Agaricus bisporus, Suillus mediterraneensis, Boletus sp., Xerocomus sp., Coprinus atramentarius, Pleurotus ostreatus, P. pulmonarius, P. eryngii, P. dryinus, Lepiota sp., Cortinarius orellanus, Armillaria mellea and Trametes quercina. The comparison of the ITS1 sequences (143 bp) with those of the databases was carried out using the BLAST algorithm, which confirmed the identification of Agaricus bisporus.&nbsp

Streptomyces Secondary Metabolites

Actinobacteria are found spread widely in nature and particular attention is given to their role in the production of various bioactive secondary metabolites. Tests on soil samples show that there can be a diversity of actinomycetes depending on the climate, the area it is growing in, how dry the soil is, and the quality of the soil. However, it was agreed after tests in Yunnan, China, that the genus Streptomyces sp. is most important in ecological function, representing up to 90% of all soil actinomycetes, and therefore helping to show the important characteristics needed of the soil actinomycete population. Streptomycete compounds are used for other biological activities, not just for antibiotics. It has been found that metabolites can be broadly divided into four classes: (1) regulatory activities in compounds, these include consideration of growth factors, morphogenic agents and siderophores, and plants promoting rhizobia; (2) antagonistic agents, these include antiprotozoans, antibacterials, antifungals, as well as antivirals; (3) agrobiologicals, these include insecticides, pesticides, and herbicides; and (4) pharmacological agents, these include neurological agents, immunomodulators, antitumorals, and enzyme inhibitors. It is found that Streptomyces hygroscopicus is one of the very best examples because it secretes in excess of 180 secondary metabolites to locate simultaneous bioactivities for a given compound. Increasingly, both its agricultural and pharmacological screenings are being used in conjunction with antimicrobial tests and have revealed several unusual aerobiological and therapeutic agents, which were hitherto unknown for biological use as antibiotics. Since streptomycetes are now being used increasingly to screen for antimicrobial activity, reports show the existence of secondary metabolites with other activities that may have been missed. Currently, nearly 17% of biologically active secondary metabolites (nearly 7600 out of 43,000) are known from streptomycetes. It has been found that soil streptomycetes are the main source used by bioactive secondary metabolites. However, recently there have been many and varied types of structurally unique and biologically active secondary metabolites found and obtained from marine actinomycetes, including those from the genus Streptomyces. Also, compounds that are synthesized by streptomycetes exhibit extreme chemical diversity. Diverse form made from from simple amino acid derivatives to high molecular weight proteides, and macrolactones from simple eight membered lactones to different condensed macrolactones. Berdy (1974) introduced the first classification scheme for antibiotics referring to the chemical structure. On the basis of Berdy’s scheme, (1996) recognized that both low and high molecular weight compounds from 63 different chemical classes are produced by streptomycetes

Pathogenic and genetic characterization of Algerian isolates of Fusarium oxysporum f. sp. lentis by RAPD and AFLP analysis

Thirty-two isolates of Fusarium oxysporum f. sp. lentis were isolated from wilted lentil plants collected from different lentil growing areas in north-west Algeria. A pathogenicity test was performed for all isolates. Results indicated that the Fol isolates represent a single race but differ in their aggressiveness on the susceptible lines. The amount of genetic variation was evaluated by polymerase chain reaction (PCR) amplification with a set of 6 RAPD primers and 3 AFLP selective nucleotide primer pairs. All amplifications revealed scorable polymorphisms among the isolates, and a total of 8 polymorphic fragments were scored for the RAPD primers and 93 for the AFLP primers. Genetic similarity between each of the isolates was calculated by using the Jaccard similarity coefficient and cluster analysis was used to generate a dendrogram showing relationship between them. The isolates could be grouped into two subpopulations based on RAPD and AFLP analysis. Results obtained indicate that there is little genetic variability among a subpopulation of Fol as identified by RAPD and AFLP markers and that there is no apparent correlation with geographical origin or aggressiveness of isolates. Also, the data suggest that Fol isolates are derived from two genetically distinct clonal lineages. Key Words: Lens culinaris, Fusarium wilt, molecular markers, pathogenicity. African Journal of Biotechnology Vol.3(1) 2004: 25-3

Valorization of a wild saprophytic edible mushroom in western Algeria: characterization and nutritional value

This study concerned a species of wild edible mushroom, oyster mushroom collected in western Algeria forests, which is well consumed by the local population. These species were identified by macroscopic, microscopic and molecular characteristics. The mushroom’s mycelium was isolated and the optimal conditions for mycelial growth were determined. Variation in different physicochemical parameters (pH, temperature, relative humidity and light) significantly influenced the mycelial growth of the mushroom on potato dextrose agar medium. Optimal mycelia growth was observed at pH 5.6, 25 °C, 100% humidity and low exposure to light. Wheat was used as spawn substrate and straw was used as fructifying substrate. The sporophores of the mushroom were obtained after one month of incubation. We cultivated this wild mushroom from its mycelium and defined the nutritional value of the obtained sporophores. The nutritional analysis was performed according to the most common analytical methods. The composition in moisture, ash, fat, protein, total carbohydrates allowed us to demonstrate that the wild edible mushroom harvested in forests of western Algeria had an important nutritional value. This wild edible mushroom was a remarkable and potential resource for development

Pathotype diversity among Algerian isolates of Pyrenophora teres f. teres

Barley Net Blotch caused by Pyrenophora teres f. teres (Ptt) is one of the most important foliar diseases in north western Algeria. The disease could cause appreciable yield losses under favorable environmental conditions. Studies on pathogen variability and distribution of virulence in Ptt are essential to identify effective sources of resistance to net blotch of barley. In this study, pathogenic variability in 48 isolates of Ptt, collected from different barley-growing areas of north-western Algeria were evaluated using 22 barley genotypes as differential hosts. Trials carried out under controlled conditions confirmed the large variation in the virulence of this fungus. The genotypes exhibited variability in response ranging from complete resistance to high susceptibility. This is the first report of pathogenic variability in Ptt in north western Algeria. The 48 isolates tested were further differentiated into 12 pathotypes according to their reaction on the host. Eight differential cultivars were resistant to all isolates tested, but others were susceptible to one or more of the isolates. The variability in the pathogen and the resistance identified in some genotypes used in this study are being investigated further to develop superior, adapted germplasm for use in barley breeding programs in north western Algeria

Genetic diversity of Verticillium dahliae isolates from olive trees in Algeria

Summary. Verticillium wilt of olive trees (Olea europaea L.), a wilt caused by the soil-borne fungus Verticillium dahliae (Kleb), is one of the most serious diseases in Algerian olive groves. To assess the pathogenic and genetic diversity of olive-infecting V. dahliae populations in Algeria, orchards from the two main olive-producing regions (north-western Algeria and Kabylia) were sampled and 27 V. dahliae isolates were recovered. For purposes of comparison, V. dahliae strains from France and Syria were added to the analysis. By means of PCR primers that specifically discriminate between defoliating (D) and non-defoliating (ND) V. dahliae pathotypes it was shown that all V. dahliae isolates belonged to the ND pathotype. The amount of genetic variation between the 43 isolates was assessed by random amplification of polymorphic DNA (RAPD). A total of 16 RAPD haplotypes were found on the basis of the presence or absence of 25 polymorphic DNA fragments. Genotypic diversity between the 27 Algerian isolates was low, with two RAPD haplotypes accounting for 70% of all isolates. Genotypic diversity was however greater between isolates from Kabylia than between isolates from north-western Algeria. Cluster analysis showed that most of the Algerian V. dahliae isolates grouped together with the French and Syrian isolates. On the basis of their ability to form heterokaryons with each other, a subset of 25 olive-pathogenic isolates was grouped into a single vegetative compatibility group (VCG). These results suggest that the olive-infecting V. dahliae populations in Algeria show limited diversity and that caution should be taken to prevent introduction of the D pathotype

The beneficial role of indigenous arbuscular mycorrhizal fungi in phytoremediation of wetland plants and tolerance to metal stress

The potential of fi ve plants namely Atriplex halimus L., A. canescens (Pursh) Nutt., Suaeda fruticosa (Forssk. ex J.F. Gmel.), Marrubium vulgare L. and Dittrichia viscosa (L.) Greuter from two selected wetlands in northwest Algeria subjected to house and industrial effluents were examined to assess their arbuscular mycorrhizal fungal (AMF) diversity and colonization, as well as to determine their tolerance and ability in accumulating metallic trace elements (MTEs). The purpose was to investigate whether, or not, these fungi are related to metallic uptake. Arbuscular mycorrhizal association was observed in all plant species, since the dual association between AMF and dark septate endophytes (DSE) was found in roots of 80% plants species. Hence, the decreasing trend of metal accumulation in most plant organs was Zn>Cu>Pb, and the most efficient species were M. vulgare> S. fruticosa>A. canescens> D. viscosa> A. halimus. The bioaccumulator factors exceeded the critical value (1.0) and the transport factors indicated that all these species were phytoremediators. Pearson correlation showed that Cd bioaccumulation and translocation were inhibited by AMF infection; meanwhile Zn, Pb and Cd accumulation were affected by AMF spore density and species richness, DSE frequency, pH, AMF and plant host. Native halophytes showed a multi-metallic resistance capacity in polluted wetlands. M. vulgare was the most efficient in metal accumulation and the best host for mycorrhizal fungi. AMF played a major role in metal accumulation and translocation

Full Length Research Paper - Pathogenic and genetic characterization of Algerian isolates of Fusarium oxysporum f. sp. lentis by RAPD and AFLP analysis

Thirty-two isolates of Fusarium oxysporum f. sp. lentis were isolated from wilted lentil plants collected from different lentil growing areas in north-west Algeria. A pathogenicity test was performed for all isolates. Results indicated that the Fol isolates represent a single race but differ in their aggressiveness on the susceptible lines. The amount of genetic variation was evaluated by polymerase chain reaction (PCR) amplification with a set of 6 RAPD primers and 3 AFLP selective nucleotide primer pairs. All amplifications revealed scorable polymorphisms among the isolates, and a total of 8 polymorphic fragments were scored for the RAPD primers and 93 for the AFLP primers. Genetic similarity between each of the isolates was calculated by using the Jaccard similarity coefficient and cluster analysis was used to generate a dendrogram showing relationship between them. The isolates could be grouped into two subpopulations based on RAPD and AFLP analysis. Results obtained indicate that there is little genetic variability among a subpopulation of Fol as identified by RAPD and AFLP markers and that there is no apparent correlation with geographical origin or aggressiveness of isolates. Also, the data suggest that Fol isolates are derived from two genetically distinct clonal lineages