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AimsThis study aimed to improve the screening strategy for the selection of biocontrol agents with high biocontrol efficacy against fire blight disease.Methods and ResultsA two-step screening procedure consisting of in-vitro laboratory tests and an ex-vivo test system using detached pear leaves was applied to 43 Bacillus strains originated from the rhizosphere and the aerial parts of apple and pear plants. The grouping of the studied strains and the tested traits based on the principal component analysis and the two-way hierarchical cluster analysis showed that siderophore production and biofilm formation are the most desirable traits in a Bacillus biocontrol agent to control fire blight disease and that rhizospheric originating strains are the most effective.ConclusionsIn contrast to the previous screening strategies that are often insufficient to select the most suitable microorganisms, this study reported an improved strategy based on the microbial competition traits to select potential Bacillus biocontrol agents with high biocontrol efficacy against fire blight disease.

Olive trees diseases harm the quality and the quantity of the harvest seriously, which causes considerable economic losses for farmers, and more importantly affects the national economy in its entirety. The aim of this investigation is to work out a recognizing pattern method, based on the analysis of the texture and supervised classification. It essentially detects and classifies olive tree diseases in order to provide the farmers with tools helping them not only to get informed of their trees' diseases, but also to know how to treat them effectively.

An olive breeding program was started in Tunisia in 1993 in order mainly to improve the fatty acid composition of the local cultivar ‘Chemlali Sfax’. ‘Zeitoun Ennour’ is a new cultivar obtained from a cross between ‘Chemlali Sfax’ and the local dual-purpose use cultivar ‘Chemchali Gafsa’. The morphological study of this cultivar showed that eleven characters dealing with fruit and endocarp differed from ‘Chemlali Sfax’, mainly regarding to their respective weights. This new cultivar had the same sensitivity to Verticillium dahliae Kleb and earlier bearing than the original variety. Its olive production was considered as high as for ‘Chemlali Sfax’ but with partial self-compatibility and late maturity. The new cultivar realized a net improvement in comparison with the original cultivar particularly regarding its fatty acid composition with very high oleic acid content (>75 %) and low palmitic and linoleic acid contents (

The incidence of fungal diseases affecting olive trees increased in Tunisia. Mycoflora isolated from diseased olive trees revealed their colonisation by several fungal species such as Fusarium oxys...

AIMS: In this study, we aimed to explore the enzymatic diversity, the entomopathogenic and the antimicrobial potentialities of fungi associated with the pistachio bark beetle, Chaetoptelius vestitus. METHODS AND RESULTS: A total of 40 isolates were screened for enzymatic diversity. Most of them, 92·5%, were able to produce at least two of the screened enzymes. Pathogenic assays performed on C. vestitus showed a high entomopathogenic activity of the isolates Ata_io_1 (A. tamarii), Fve_io_1 (F. verticillioides), Tpi_io_1 (T. pinophilus), Pal_io_1 (P. album), Pbi_io_2 (Penicillium bilaiae) and Pch_io_1 (P. chrysogenum), as based on mean mortality of C. vestitus. A screening of antimicrobial activity using well diffusion method showed that the isolates Tro_io_1 (T. pinophilus), Tat_io_1 (T. atroroseus) and Pch_io_1 (P. chrysogenum) presented the highest antibacterial activity. Furthermore, Mgu_io_1 (M. guilliermondii), Asc_io_1 (A. sclerotiorum), Ata_io_1 (A. tamarii), G. lavendula (Gla_io_1), Pva_io_1 (P. variotii), Pul_io_1 (P. ulaiense), Tat_io_1 (T. atroroseus) and Tro_io_1 (T. roseum) were active against at least two of the three tested fungal phytopathogens. CONCLUSIONS: Fungal isolates representing entomopathogenic activity and a broad spectrum of antimicrobial activities can be considered as promising resources for biological pistachio trees protection. SIGNIFICANCE AND IMPACT OF THE STUDY: Fungi associated with C. vestitus were investigated for detecting their potential biotechnological applications.

Rapid climate and environmental change at limited, regional, and general scales have been a major concern for researchers in a number of fields, such as topography, economy, environment, and sustainable development. Changes in land cover and land use have taken into account due to potential impacts on soil depletion, amplified run-off, water balance, and climate change. A detailed understanding of the characteristics of land exploitation and land structure is indispensable for the study of their influences on life and nature. In addition, urban extension is a major form of land extraction and land transformation, as it relates to the rise in population and the availability of financial services. Remote sensing records have been shown to be important for reporting and perceiving urban development and transition, and for providing critical information for future growth. Transformation and shift identification are the tools used to recognise distinctions in a land cover by tracking them at various times. In addition, various change identification and detection approaches are routinely tested with the goal of providing the greatest change detection deductions for a particular appliance. This review would aim to establish a practical plan that combines remote sensing techniques, on the one hand, and modelling approaches, on the other, to track land use, to cover changes, and to predict future trends.

Large volumes of Produced Water (PW) are being generated to surface facilities from underground reservoirs during the process of oil and gas extraction. PW is a mixture containing a complex composition of organic and inorganic pollutants threatening the environment. A huge load of salt in PW is mainly depending on the geological framework of the reservoir. In this study, we investigated a lab-scale evaporation-crystallization process coupled with ventilation for the recovery of valuables salt from PW treated by sand filtration. The results show two successive crystallizations of 96,62% and 92,25% Sodium chloride (NaCl), respectively. The effect of ventilation on the acceleration of the crystallization is noticeable.

Artificial Intelligence is an emerging technology in the field of agriculture. Artificial Intelligence-based tools and equipment have actually taken the agriculture sector to a different level. This new technology has improved crop production and enhanced instantaneous monitoring, processing, and collection. The most recent computerized structures using remote sensing and drones have made a significant contribution to the agro-based domain. Moreover, remote sensing has the capability to support the development of farming applications with the aim of facing this main defy, via giving cyclic records on yield status during studied periods at diverse degrees and for diverse parameters. Various hi-tech, computer-supported structures are created to determine different central factors such as plant detection, yield recognition, crop quality, and several other methods. This paper includes the techniques employed for the analysis of collected information in order to enhance the productivity, forecast eventual threats, and reduce the task load on cultivators.

BackgroundOlive production is the main agricultural activity in Tunisia. The diversity of fungi was explored in two different olive groves located in two distant geographical zones in Sfax (Tunisia) with different management practices.ResultsFungal isolation was made from soil and the major olive tree pests, namely the Olive fly,Bactrocera oleaeGmelin (Diptera: Tephritidae), and the Olive psyllid,Euphyllura olivinaCosta (Homoptera: Psyllidae). A total of 34 fungal isolates were identified according to their phenotypic, genotypic, biochemical and biological activities. Twenty fungal species were identified belonging to six different genera (Alternaria,Aspergillus,Cladosporium,Fusarium,LecanicilliumandPenicillium) by the analysis of their ITS1–5.8S–ITS2 ribosomal DNA region. Different bioassays performed in this work revealed that 25/34 (73.5%) of the identified fungal isolates showed an entomopathogenic and/or antagonistic activity, 9/34 (26.5%) of them displayed phytopathogenic features.ConclusionsFungal species that showed entomopathogenic and/or antagonistic potentialities and that are non-phytopathogenic, (17/34; 50%) of our fungal isolates, could be explored for olive protection against fungal diseases and pests, and might have a future application as biocontrol agents.

In this study, numerous properties of pistachio tree (Pistacia vera L.) varieties such as WAHIDI, UZUN, RED ALEPPO, OUHADI, AYIMI, KIRMIZI, MOMTEZ, ACHOURY, KERMAN, EL-GUETAR, MATEUR, and NOURI were determined. Physical and mechanical properties of pistachio fruit [(length/width) fruit ratio, fruit form, color of pedicel scar, form of pedicel scar, relief of pedicel scar, percentage of empty fruits, number of knotted flowers/fruit cluster, fruit drop rate, number of fruits/cluster, and percentage of mature fruits] were evaluated. Principal component analysis was applied in the aim to identify the importance of studied parameters and their corresponding correlations. On the basis of obtained results, the most influential fruit character of first principal component (contribution rate = 35%) was relief of pedicel scar, and the most dominant fruit attribute of second principal component (contribution rate = 22%) was form of pedicel scar. Circle of correlation confirmed first that fruit maturity is associated with pistachio size development. Second, to have a high fruit yield, the relief of pedicel scar must be low. Furthermore, Bayesian Networks method was showed in the aim to reveal the relationships between different parameters. Finally, the dendrogram of selected pistachio varieties demonstrates that a high similitude existed between varieties with a similarity value of 0.64. In fact, the dendrogram of pistachio fruit revealed that all studied accessions were divided into three main clusters. Hierarchical clustering revealed that a strong connection existed between physiological and yield traits. These results illustrate a possible use of desired features at least in various infra-specific investigations in P. vera L. to highlight hidden relationships between varieties.

In this paper, the time-varying correlations are estimated for the purpose of examining whether CDS can act as a hedge and safe haven for the European stock sectors. Similarly, the implications for portfolio design are also evaluated on daily and weekly data span bases, concerning the period ranging from December 2007 to September 2017. Overall, the empirical results appear to reveal that the safe haven roles associated with the CDS and the portfolio design prove to differ noticeably across the time horizons as well as from one model to another. Likewise, choosing CDS or VSTOXX futures as hedging instrument seem to depend heavily on data frequency and the models applied. The interest lying behind the conduction of such a study is twofold: on the one hand, it should serve as a guide to investors through enabling them to opt for the most effective strategies useful for hedging the stock sectors' relating risks and, on the other hand, to highlight the models’ specifications associated impacts. JEL classification: C32, C58, G11, G15, Keywords: CDS index, VSTOXX futures, Stock sector, DCC, ADCC, Hedge-safe haven, Optimal hedge ratios, Portfolio variance

The olive trees (Olea europaea L.) have been cultivated for millennia in the Mediterranean basin and its oil has been an important part of human nutrition in the region. In order to distinguish between olive accessions, morphological and biological characters have been widely and commonly used for descriptive purposes and have been used to characterize olive accessions. A comparative study of morphological characters of olive accessions grown in Tunisia was carried out and analyzed using Bayesian Networks (BN) and Principal Components Analysis (PCA). The obtained results showed that averages of fruit and kernel weights were 2.27 grams and 0.41 grams, respectively. Besides, a relatively moderate level of variation (51.22%) being explained by four Principal components. BN revealed that geographical localisation plays a role in the increase of tree habit, size of lenticels and leaf shape. A dendrogram has been carried out in the aim to classify studied olive accessions. We proposed a novel method of analysis based on the three-step scheme, in which first the data set is clustered, then olive tree features are evaluated. The studied accessions can be divided into four main groups by cutting the dendrogram at a similarity value of 0.645. Different relationships are studied and highlighted, and finally the collected features are subjected to a global principal component analysis. Obtained results confirmed that core surface was negatively correlated with geographical location (r = -0.52, p

Precision agricultural skill has constructed and will still construct the road we are moving into this novel theory of precision agriculture. By increasing the inspection and appliance of inputs on the land, farmers are changing from a usual, standardized treatment of every agricultural land to a perfect treatment for as little as possible districts. Remote sensing processes offer a basis for which vegetal stress and growth reaction can be estimated. Remote sensing research based on terrestrial and spatial domains has demonstrated that numerous kinds of plant illness, through pre-visual infection signs for pathogens, hostile species and also plant health indicators, can be identified through aerial hyperspectral imaging. Inspecting foliage using remote sensing data necessitates understanding of the organization and role of foliage and its reflectance characteristics. Sensors have been ameliorated to calculate the reflectance of incident bright at numerous wavebands and have been associated to plant evolution and plant cover. Remote sensing technology has the major advantage to obtaining data about a given entity or region without having physical exchange and frequently employs surface-based instruments or spatial pictures. Remote sensing would be considered as an economic and relevant instrument for land-scale pest controlling and study.

Oomycete and fungal pathogens, mainly Phytophthora and Fusarium species, are notorious causal agents of huge economic losses and environmental damages. For instance, Phytophthora ramorum, Phytophthora cryptogea, Phytophthora plurivora and Fusarium solani cause significant losses in nurseries and in forest ecosystems. Chemical treatments, while harmful to the environment and human health, have been proved to have little or no impact on these species. Recently, biocontrol bacterial species were used to cope with these pathogens and have shown promising prospects towards sustainable and eco-friendly agricultural practices. Olive trees prone to Phytophthora and Fusarium disease outbreaks are suitable for habitat-adapted symbiotic strategies, to recover oomycetes and fungal pathogen biocontrol agents. Using this strategy, we showed that olive trees-associated microbiome represents a valuable source for microorganisms, promoting plant growth and healthy benefits in addition to being biocontrol agents against oomycete and fungal diseases. Isolation, characterization and screening of root microbiome of olive trees against numerous Phytophthora and other fungal pathogens have led to the identification of the Bacillus velezensis OEE1, with plant growth promotion (PGP) abilities and strong activity against major oomycete and fungal pathogens. Phylogenomic analysis of the strain OEE1 showed that B. velezensis suffers taxonomic imprecision that blurs species delimitation, impacting their biofertilizers’ practical use. Genome mining of several B. velezensis strains available in the GenBank have highlighted a wide array of plant growth promoting rhizobacteria (PGPR) features, metals and antibiotics resistance and the degradation ability of phytotoxic aromatic compounds. Strain OEE1 harbours a large repertoire of secreted and volatile secondary metabolites. Rarefaction analysis of secondary metabolites richness in the B. velezenis genomes, unambiguously documented new secondary metabolites from ongoing genome sequencing efforts that warrants more efforts in order to assess the huge diversity in the species. Comparative genomics indicated that B. velezensis harbours a core genome endowed with PGP features and accessory genome encoding diverse secondary metabolites. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of OEE1 Volatile Organic Compounds (VOCs) and Liquid Chromatography High Resolution Mass Spectrometry (LC-HRMS) analysis of secondary metabolites identified numerous molecules with PGP abilities that are known to interfere with pathogen development. Moreover, B. velezensis OEE1 proved effective in protecting olive trees against F. solani in greenhouse experiments and are able to inhabit olive tree roots. Our strategy provides an effective means for isolation of biocontrol agents against recalcitrant pathogens. Their genomic analysis provides necessary clues towards their efficient implementation as biofertilizers.

Halophyte Limoniastrum monopetalum, an evergreen shrub inhabiting the Mediterranean region, has well-documented phytoremediation potential for metal removal from polluted sites. It is also considered to be a medicinal halophyte with potent activity against plant pathogens. Therefore, L. monopetalum may be a suitable candidate for isolating endophytic microbiota members that provide plant growth promotion (PGP) and resistance to abiotic stresses. Selected for biocontrol abilities, these endophytes may represent multifaceted and versatile biocontrol agents, combining pathogen biocontrol in addition to PGP and plant protection against abiotic stresses. In this study 117 root culturable bacterial endophytes, including Gram-positive (Bacillus and Brevibacillus), Gram-negative (Proteus, Providencia, Serratia, Pantoea, Klebsiella, Enterobacter and Pectobacterium) and actinomycete Nocardiopsis genera have been recovered from L. monopetalum. The collection exhibited high levels of biocontrol abilities against bacterial (Agrobacterium tumefaciens MAT2 and Pectobacterium carotovorum MAT3) and fungal (Alternaria alternata XSZJY-1, Rhizoctonia bataticola MAT1 and Fusarium oxysporum f. sp. radicis lycopersici FORL) pathogens. Several bacteria also showed PGP capacity and resistance to antibiotics and metals. A highly promising candidate Bacillus licheniformis LMRE 36 with high PGP, biocontrol, metal and antibiotic, resistance was subsequently tested in planta (potato and olive trees) for biocontrol of a collection of 14 highly damaging Fusarium species. LMRE 36 proved very effective against the collection in both species and against an emerging Fusarium sp. threatening olive trees culture in nurseries. These findings provide a demonstration of our pyramiding strategy. Our strategy was effective in combining desirable traits in biocontrol agents towards broad-spectrum resistance against pathogens and protection of crops from abiotic stresses. Stacking multiple desirable traits into a single biocontrol agent is achieved by first, careful selection of a host for endophytic microbiota recovery, second, stringent in vitro selection of candidates from the collection, and third, application of the selected biocontrol agents in planta experiments. That pyramiding strategy could be successfully used to mitigate effects of diverse biotic and abiotic stresses on plant growth and productivity. It is anticipated that the strategy will provide a new generation of biocontrol agents by targeting the microbiota of plants in hostile environments.

Verticillium wilt is one of the most severe diseases of olive. In this study, differential physiological and biochemical responses of two olive cultivars differing by their susceptibility to Verticillium dahliae were investigated using gene expression analyses and monitoring of some physiological and biochemical parameters. Results revealed that early up-regulation of SOD gene, together with a reduced scavenging system activity, resulted in higher H2O2 burst in the resistant cultivar as compared to the susceptible one. In addition, early and simultaneous up-regulation of chitinase and β-1,3-glucanase genes is correlated with reduced susceptibility and wilt symptoms in the resistant cultivar Sayali. The expression level of genes coding for PR10 protein, PLD and WRKY transcription factor was higher in the resistant cultivar, which indicates that induction of the SA pathway is essential for conferring resistance against V. dahliae and reduction of wilt symptoms. Furthermore, comparison of the SA-related genes expression patterns with those followed by the H2O2 burst, chitinase and β-1,3-glucanase genes, revealed that high SA level and H2O2 production, together with enhanced PR proteins activity are a key factor for resistance. As JA-related genes, a strong co-up-regulation of jasmonate ZIM domain and bHLH-binding factor responsive to JA was recorded in both cultivars, except that the extent of this induction was higher in the resistant cultivar. Similarly, the ERF related gene was differentially up-regulated in the two cultivars, which suggests that ET may play a role in the enhancement of olive resistance to V. dahliae. Overall, our findings provide important clues for designing strategies to restrict the effects of this disease.

In the last years, the spread of wilt and dieback diseases in olive trees (Olea europaea), caused by the soilborne pathogens, has often been related to intensive modern farming of highly productive cultivars, planted at high densities, usually in an irrigated system. Plants have developed different strategies to trigger defense signaling to defend themselves and to maintain surveillance against pathogens. However, the response of olive tree to pathogen infections is not well studied yet. The present work is aimed at studying the response of olive tree to soilborne fungi isolated from different affected areas in Tunisia, such as Fusarium spp., Verticillium dahliae, Cylindrocarpon sp. and Rhizoctonia solani. Artificial inoculation on young olive trees cv. ‘Chemlali’ confirmed the pathogenicity of all these pathogens by reproducing typical symptoms of root rot with varied degrees. Biochemical analysis realized after 21 days of inoculation has shown that chlorophyll pigments, solubles sugar, total polyphenols and proline contents were highly detected in plants infected by V. dahliae and F. solani. The expression of four genes Olest 06, Olest 47, Olest 73 and Olest 30 involved in the signaling biotic and abiotic stress and transcriptional activation of pathogenesis-related proteins was analyzed by reverse transcription-PCR after 21 days of inoculation. The transcript level of Olest 73 was relatively constant in all tested fungi. The expression of gene Olest 47 was observed in the leaves of olive in vitro plants infected by V. dahliae and Fusarium spp., and the gene expression of Olest 30 was detected only in plants infected by V. dahliae. No PCR product was detected for Olest 06 in all inoculated olive trees. In conclusion, according to results obtained by biochemical and molecular analysis, the olive trees develop variable responses to pathogenic soil fungi attack.

BACKGROUND This study aims to characterise the antibacterial activity of a novel Bacillus methylotrophicus strain named 39b against tumourigenic Agrobacterium tumefaciens C58 and B6 strains. It also aims to identify the compound that is responsible for its activity and to evaluate its efficiency to control crown gall disease in tomato plants. RESULTS B. methylotrophicus strain 39b was found to stop the growth of phytopathogenic A. tumefaciens strains in in vitro experiments. Lipopeptides – surfactins, iturins and fengycins – were detected under various isoforms by mass spectrometry analysis of the methanolic extract. The active principle acting against Agrobacterium strains was isolated from TLC plates and identified by mass spectrometry as surfactin. The strain was effective in reducing the weight and the number of galls induced by A. tumefaciens strains on tomato plants. Total inhibition of gall formation was observed using the antibacterial compounds. CONCLUSION B. methylotrophicus strain 39b exhibited antibacterial activity against phytopathogenic A. tumefaciens C58 and B6 both in vitro and in vivo. Lipopeptides are the main compounds that confer the biocontrol ability. This strain has the potential to be developed as a biological control agent for crown gall disease. © 2016 Society of Chemical Industry

Three tetraploid somatic hybrid lines produced by protoplast fusion between a dihaploid potato, Solanum tuberosum, cultivar BF15 and the wild potato species Solanum berthaultii were evaluated here for their response to different soil-borne pathogens, that is Fusarium solani, Pythium aphanidermatum and Rhizoctonia solani as well as to infection by potato virus Y (PVY). Both hybrid and BF15 plants grown in vitro were inoculated with the tested pathogen strains, that is R. solani, P. aphanidermatum, or F. solani. The growth level and disease severity index of these plants were compared to the susceptible commercial cultivar Spunta. A better growth of inoculated hybrid plants and restricted disease symptoms were observed in comparison with the commercial plants. Under glasshouse conditions and after inoculation with R. solani and P. aphanidermatum, improved resistance of the hybrid plants to these pathogens was confirmed. Indeed, these plants showed no significant damage following inoculation and a better development in R. solani-infected plants. The susceptibility of the hybrid tubers to R. solani, P. aphanidermatum, and to F. solani infection was also determined. A significant reduction of tissue colonisation was observed in all the hybrid lines compared to the cultivated cultivars. The STBc and STBd hybrids also showed improved resistance to the PVY ordinary strain (PVYo) under glasshouse conditions.

Organic matter (OM) is a vital component for a healthy soil, its lack arise a major problem for farmers who need to use commercialized fertilizers with high costs. Considering circular economy approach and for increasing OM availability, water soaked date palm waste was co-composted with goat manure in aerated windrow to produce a soil organic amendment. The OM biodegradation was mainly controlled based on biological parameters and spectroscopic techniques. The results showed a rapid temperature increase during the first week, and a relatively long compost maturity phase. The OM content reduction was of 36% and C/N ratio shifted from 60 to 20 at the process end. During the composting process, the specific ultraviolet absorbance SUVA254, SUVA269 and the SUVA280 values increase confirmed the OM and hydrophilic compounds degradation, as well as substrate content oxidation into aromatic compounds. The Fourier Transform Infrared Spectroscopy (FTIR) analyses of the different samples collected during the process exhibited both OM biodegradation and mineralization. The 3 absorption ratios 1650/2845, 1525/2925 and 2920/1640 confirmed an aromaticity increase by aromatic structures biosynthesis, such as humic-like and fulvic-like substances, with the decomposition/transformation of aliphatic components, polysaccharides, and alcohols. Fluorescence excitation-emission matrix (FEEM) spectroscopy coupled with parallel factor analysis (PARAFAC) evidenced the dissolved organic matter (DOM) humification. A four-component model was obtained, i.e. humic-like component (S1, S2 and S3) and fulvic-like component (S4). The produced compost didn't exhibit any phytotoxicity evidenced by cress seed germination index exceeding 80%. All the analyses confirmed the good quality of the compost issued from mixed date palm waste and goat manure.

The use of antagonists in the biocontrol of soilborne pathogens is a promising approach to manage many diseases. In this context, Bacillus velezensis strain OEE1, isolated from endogenous root tissue of olive trees, showed the most effective antifungal activity under in vitro conditions against V. dahliae with inhibition rate exceeding 92% using the dual culture method to investigate effects of diffusible compounds. This antagonism was also demonstrated with volatile and extracellular compounds where fungus growth was reduced by about 40% and 60% respectively. Gnotobiotic study of axenic in vitro olive plants, artificially inoculated with V. dahliae, using B. velezensis OEE1 cells led to a considerable reduction in Verticillium wilt severity and the disease index effectively decreased for preventive and curative treatments. Vegetative growth showed equally an interesting improvement. These potentialities are provided due to the production of numerous secondary metabolites detected by antibiotic biosynthesis genes amplification. The efficacy of B. velezensis OEE1 to suppress Verticillium wilt of olive tree was evaluated also under field conditions. This experiment revealed that B. velezensis OEE1 significantly decreased final mean disease severity index (FMS), percentage of dead plants (PDP) and area under disease progress curve (AUDPC) and reduced similarly microsclerotia density in the naturally infested soil.

AIM: This study investigated the biodiversity of fungi associated with the pistachio bark beetle, Chaetoptelius vestitus, in Tunisia. We evaluated the phytopathogenic activities and tested antagonistic potentialities with respect to phytopathogens. METHODS AND RESULTS: A total of 41 fungal isolates were randomly isolated from C. vestitus adults and galleries. We identified 28 species belonging to 13 genera using ITS sequences of the ribosomal RNA operons. Pathogenicity assays performed using the excised shoot method revealed that isolates Aal_io_1 (Alternaria alternata), Feq_io_1 (Fusarium equiseti), Fgra_io_1 (Fusarium graminearum), Fve_io_1 (Fusarium verticilloides), Tro_io_1 (Trichothecium roseum) and Nqu_io_1 (Nothophoma quercina) displayed a high pathogenic activity on pistachio stems. Estimation of the antagonistic potentialities of isolated fungi against several phytopathogenic isolates as tested using a dual‐culture method showed that isolates Tpi_io_1 (Talaromyces pinophilus), Pbi_io_2 (Penicillium bilaiae), Asc_io_1 (Aspergillus sclerotiorum) and Gla_io_1 (Geosmithia lavendula) displayed a broad range of antagonistic activities. CONCLUSION: Fungi associated with C. vestitus had a variable range of pathogenic activity on pistachio stem. Phytopathogenic fungi were antagonized by different fungal isolates which could be promising in pistachio protection against phytopathogenic fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first that investigated the diversity of fungi associated with C. vestitus and evaluated both their phytopathogenic activity and antagonistic potential against fungal phytopathogens.

Aim This study investigated the bacterial diversity of dead insects collected from olive tree orchards widely cultivated in Tunisia. We aimed to explore metabolic diversity, screen enzymatic activities for biotechnological applications and carry out preliminary bioassays for bio-insecticide development. Methods and results A total of 50 bacteria strains were randomly isolated from four different biotopes situated in Sfax (Tunisia). 16S rRNA gene sequencing was used to identify 24 species, and isolates were evaluated for enzymatic activity and antimicrobial potential. Nineteen of the total number of Bacillus strains have enzymatic activity compared to strains from the other genera (14/50). Our bacterial collection was evaluated for antimicrobial potential against bacterial and fungal isolates. Isolates B8-2 (Bacillus subtilis) showed strong antibacterial activities and isolates B2-3 (Bacillus licheniformis) and B10-1 (Serratia marcescens) showed the highest antifungal activity. Seventeen of the total number of isolates caused greater than 50% mortality rate of second and fourth instar larvae of Ephestia kuehniella. Conclusion The selected species from olive orchards represent a broad spectrum of antimicrobial and insecticidal activities and can be considered promising resources in biological control. Significance and impact of the study Bacteria isolated from olive pests in olive orchards were investigated for detecting their potential biotechnological applications.

Date palm (Phoenix dactylifera L.) plantations in North Africa are nowadays threatened with the spread of the Bayoud disease caused by Fusarium oxysporum f. sp. albedinis, already responsible for destroying date production in other infected areas, mainly in Morocco. Biological control holds great promise for sustainable and environmental-friendly management of the disease. In this study, the additional benefits to agricultural ecosystems of using plant growth promoting rhizobacteria (PGPR) or endophytes are addressed. First, PGPR or endophytes can offer an interesting bio-fertilization, meaning that it can add another layer to the sustainability of the approach. Additionally, screening of contrasting niches can yield bacterial actors that could represent wardens against whole genera or groups of plant pathogenic agents thriving in semi-arid to arid ecosystems. Using this strategy, we recovered four bacterial isolates, designated BFOA1, BFOA2, BFOA3 and BFOA4, that proved very active against F. oxysporum f. sp. albedinis. BFOA1–BFOA4 proved also active against 16 Fusarium isolates belonging to four species: F. oxysporum (with strains phytopathogenic of Olea europaea and tomato), F. solani (with different strains attacking O. europaea and potato), F. acuminatum (pathogenic on O. europaea) and F. chlamydosporum (phytopathogenic of O. europaea). BFOA1–BFOA4 bacterial isolates exhibited strong activities against another four major phytopathogens: Botrytis cinerea, Alternaria alternata, Phytophthora infestans, and Rhizoctonia bataticola. Isolates BFOA1–BFOA4 had the ability to grow at temperatures up to 35°C, pH range of 5–10, and tolerate high concentrations of NaCl and up to 30% PEG. The isolates also showed relevant direct and indirect PGP features, including growth on nitrogen-free medium, phosphate solubilization and auxin biosynthesis, as well as resistance to metal and xenobiotic stress. Phylogenomic analysis of BFOA1–BFOA4 isolates indicated that they all belong to Bacillus halotolerans, which could therefore considered as a warden against Fusarium infection in plants. Comparative genomics allowed us to functionally describe the open pan genome of B. halotolerans and LC-HRMS and GCMS analyses, enabling the description of diverse secondary metabolites including pulegone, 2-undecanone, and germacrene D, with important antimicrobial and insecticidal properties. In conclusion, B. halotolerans could be used as an efficient bio-fertilizer and bio-control agent in semi-arid and arid ecosystems.

Aims: During the last two decades, verticillium wilt of olive has spread to young olive orchards where highly susceptible crops such as potato, watermelon and tomato are cultivated near to olive orchards. It was therefore hypothesized that there is an adaptation phenomenon that drives the pathogenicity of V. dahliae in order to infect a broad range of hosts. Therefore, it will be useful to identify the factors that increase the severity of the pathogen which helps growers to implement the appropriate crop rotation program. Place and Duration of Study: This work was performed in the Laboratory of Phytopathology at the Original Research Article

Aims: During the last two decades, verticillium wilt of olive has spread to young olive orchards were it causes severe yield losses and death of olive trees in southern and central regions of Tunisia. Therefore, identification of the causal agent as well as the study of its pathogenicity will be useful for design the appropriate management program. Place and Duration of Study: This work was performed in the Laboratory of Phytopathology at the Olive Tree Institute (Sfax, Tunisia) between July 2014 and June 2015. Original Research Article Gharbi et al.; JALSI, 4(3): 1-8, 2016; Article no.JALSI.23696 2 Methodology: This study was conducted using phenotypic and molecular methods to identify the causal agent of the decline and death of olive trees. The pathogen was recovered from infested tissues using a potato dextrose agar medium. Identity of the isolates was confirmed by ITS-RFLP and sequencing. Pathogenicity of the isolates was evaluated by infection bioassay on young olive plants. Results: All the fungal isolates were hyaline, flocculose and produced microsclerotia after 15 days of incubation at 25°C, which is in agreement with the identification key of Verticillium species. All the isolates were characterized by ITS-RFLP and sequencing of the internal transcribed spacer. All the isolates produced 470 bp using primers ITS1/ITS4. Digestion of the ITS product using EcoRI and HaeIII produced two fragment of 250 and 220 bp and three fragment of 300, 150, and 20 bp respectively. Pathogenicity was evaluated on two-year old olive plants using an artificial infection bioassay. After 15 days of inoculation, similar symptoms were produced as natural infection. Symptoms of wilt developed rapidly and caused the death of more than 50% of the inoculated plants. Conclusion: V. dahliae is present in almost all growing olive regions of Tunisia. However, local V. dahliae populations in Tunisia is predominated by a highly pathogenic clone which is able to overcome the resistance of the main olive cultivar.