Papers by Essaid Ait Barka
Journal of Fungi
Wheat and barley are the main cereal crops cultivated worldwide and serve as staple food for a th... more Wheat and barley are the main cereal crops cultivated worldwide and serve as staple food for a third of the world’s population. However, due to enormous biotic stresses, the annual production has significantly reduced by 30–70%. Recently, the accelerated use of beneficial bacteria in the control of wheat and barley pathogens has gained prominence. In this review, we synthesized information about beneficial bacteria with demonstrated protection capacity against major barley and wheat pathogens including Fusarium graminearum, Zymoseptoria tritici and Pyrenophora teres. By summarizing the general insights into molecular factors involved in plant-pathogen interactions, we show to an extent, the means by which beneficial bacteria are implicated in plant defense against wheat and barley diseases. On wheat, many Bacillus strains predominantly reduced the disease incidence of F. graminearum and Z. tritici. In contrast, on barley, the efficacy of a few Pseudomonas, Bacillus and Paraburkholde...
Microorganisms, 2021
In the coming century, climate change and the increasing human population are likely leading agri... more In the coming century, climate change and the increasing human population are likely leading agriculture to face multiple challenges. Agricultural production has to increase while preserving natural resources and protecting the environment. Drought is one of the major abiotic problems, which limits the growth and productivity of crops and impacts 1–3% of all land.To cope with unfavorable water-deficit conditions, plants use through sophisticated and complex mechanisms that help to perceive the stress signal and enable optimal crop yield are required. Among crop production, wheat is estimated to feed about one-fifth of humanity, but faces more and more drought stress periods, partially due to climate change. Plant growth promoting rhizobacteria are a promising and interesting way to develop productive and sustainable agriculture despite environmental stress. The current review focuses on drought stress effects on wheat and how plant growth-promoting rhizobacteria trigger drought stre...
International Journal of Molecular Sciences, 2019
Phenolic compounds are implied in plant-microorganisms interaction and may be induced in response... more Phenolic compounds are implied in plant-microorganisms interaction and may be induced in response to plant growth-promoting rhizobacteria (PGPRs). Among PGPR, the beneficial bacterium Paraburkholderia phytofirmans PsJN was previously described to stimulate the growth of plants and to induce a better adaptation to both abiotic and biotic stresses. This study aimed to investigate the impact of PsJN on grapevine secondary metabolism. For this purpose, gene expression (qRT-PCR) and profiling of plant secondary metabolites (UHPLC-UV/DAD-MS QTOF) from both grapevine root and leaves were compared between non-bacterized and PsJN-bacterized grapevine plantlets. Our results showed that PsJN induced locally (roots) and systemically (leaves) an overexpression of PAL and STS and specifically in leaves the overexpression of all the genes implied in phenylpropanoid and flavonoid pathways. Moreover, the metabolomic approach revealed that relative amounts of 32 and 17 compounds in roots and leaves, ...
Biological Control, 2019
Dieback and canker of pistachio shoots and limbs is a commercially significant disease in Iran. P... more Dieback and canker of pistachio shoots and limbs is a commercially significant disease in Iran. Paecilomyces formosus (Sakag., May., Inoue and Tada) Houbraken & Samson is considered as the major causal agent of this malady. Actinomycetes and particularly members of the genus Streptomyces are well known as biocontrol agents for many plant diseases; they achieve this by production of bioactive metabolites and hydrolytic enzymes. The present study aimed to exploit Streptomyces isolates to biologically control P. formosus in vitro and in greenhouse experiments. Fifty two actinomycetes isolates were evaluated for their antagonistic effect against P. formosus isolated from diseased orchards. Considering their in vitro antagonistic performance, two isolates, designated as BH4-1 and BH4-3 were selected for molecular identification and in vivo experiment to be evaluated for biocontrol efficacy. Partial sequences of 16S rDNA unveiled their identity as two strains of Streptomyces misionensis with 99.9% sequence homology. For in vivo greenhouse experiments, inoculation of artificially made wounds on pistachio young trees stems performed with spore suspensions and culture extracts of either of the two bioactive S. misionensis Cercos et al. strains alone and/or together with P. formosus spore suspensions. Cupravit® was used as fungicide control. To evaluate the effect of the biocontrol test agents on the development of disease symptoms and severity, after about nine months, canker severity score, length and width of internal discolored lesions and frequency of P. formosus re-isolation from lesion margins were measured. The recorded disease criteria for treatments receiving S. misionensis strains were significantly in favor of bio-controlling the disease compared to the controls.
Frontiers in microbiology, 2018
The use of plant-associated bacteria has received many scientific and economic attention as an ef... more The use of plant-associated bacteria has received many scientific and economic attention as an effective and alternative method to reduce the chemical pesticides use in agriculture. The genus includes at least 90 species including pathogenic strains, plant pathogens, as well as plant beneficial species as those related to , which has been reported to be associated with plants and exerts a positive effect on plant growth and fitness. PsJN, a beneficial endophyte able to colonize a wide range of plants, is an established model for plant-associated endophytic bacteria. Indeed, in addition to its plant growth promoting ability, it can also induce plant resistance against biotic as well as abiotic stresses. Here, we summarized an inventory of knowledge on PsJN-plant interaction, from the perception to the resistance mechanisms induced in the plant by a way of the atypical colonization mode of this endophyte. We also have carried out an extensive genome analysis to identify all gene clust...
Frontiers in plant science, 2018
Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen... more Abiotic factors inducing osmotic stress can affect plant immunity and resistance against pathogen attack. Although a number of studies have characterized grapevine responses to various forms of biotic and abiotic stresses, the relationships between osmotic stress response and susceptibility of mature berries to still remain unknown. In this study, we investigated the effects of osmotic stress and abscisic acid (ABA) on defense responses of mature grapevine berries before and after infection. We focused on the possible involvement of polyamines in the interaction between osmotic stress response and susceptibility to . We showed that osmotic stress induced by PEG or sucrose, and exogenous ABA induce transient but low defense responses, including weak expression of genes and phytoalexin synthesis in mature berries. This was accompanied by an upregulation of involved in ABA biosynthesis and a large production of free polyamines. However, osmotic stress followed by infection primed berri...
Frontiers in plant science, 2016
Plant innate immunity serves as a surveillance system by providing the first line of powerful wea... more Plant innate immunity serves as a surveillance system by providing the first line of powerful weapons to fight against pathogen attacks. Beneficial microorganisms and Microbial-Associated Molecular Patterns might act as signals to trigger this immunity. Burkholderia phytofirmans PsJN, a highly efficient plant beneficial endophytic bacterium, promotes growth in a wide variety of plants including grapevine. Further, the bacterium induces plant resistance against abiotic and biotic stresses. However, no study has deciphered triggered-mechanisms during the tripartite interaction between grapevine, B. phytofirmans PsJN and Botrytis cinerea. Herein, we showed that in contrast with classical rhizobacteria, which are restricted in the root system and act through ISR, B. phytofirmans PsJN is able to migrate until aerial part and forms at leaves surface a biofilm around B. cinerea mycelium to restrict the pathogen. Nevertheless, considering the endophytic level of PsJN in leaves, the plant pr...
Http Www Theses Fr, 1993
La progression du gel et les consequences metaboliques et structurales de la formation de glace a... more La progression du gel et les consequences metaboliques et structurales de la formation de glace au sein de l'appareil caulinogemmaire des vignes champenoises (vitis vinifera l. ) au cours des gelees d'hiver et de printemps ont ete etudies a l'aide de techniques physiques, biochimiques et histo-cytologiques. La prise en glace des tissus qui debute dans le sarment, gagne la base du bourgeon latent hiverne, puis ses composants primaire et secondaire. Le profil de cristallisation des sarments apparait bi-exothermique, celui des bourgeons latents est tri-exothermique. Ce dernier, a l'approche de la periode de debourrement devient mono-exothermique ce qui exprime une prise en glace brutale et totale de l'ensemble des tissus gemmaires due a la perte de leur capacite a developper le phenomene de surfusion. La nature et la localisation des degats tissulaires et cellulaires engendres par le froid dependent des temperatures de cristallisation et de l'etat physiologique de l'organe. Seul le bourgeon en cours de debourrement a montre des variations significatives de sa teneur en proline en fonction de la temperature
Plant Science, 2015
Highlights-Chilling night leads to distinct responses depending on grapevine cultivars-Several me... more Highlights-Chilling night leads to distinct responses depending on grapevine cultivars-Several metabolites are distinctly modulated in response to cold-The results explain partly the difference in cold susceptibility of used cultivars ABSTRACT Cold nights impact grapevine flower development and fruit set. Regulation at the female meiosis step may be of considerable importance for further understanding on how flower reacts to cold stress. In this study, the impact of chilling temperature (0°C overnight) on carbon metabolism was investigated in the inflorescences of two cultivars, Pinot noir (Pinot) and Gewurztraminer (Gewurtz.). Fluctuations in photosynthetic activity and carbohydrate metabolism were monitored by analyzing gas exchanges, simultaneous photosystem I and II activities, and carbohydrate content. Further, the expression of PEPc, PC, FNR, ISO, OXO, AGPase, amylases and invertase genes, activities of various enzymes, as well as metabolomic analysis were attained. Results showed that the chilling night has different impacts depending on cultivars. Thus, in Gewurtz., net photosynthesis (P n) was transiently increased whereas, in Pinot, the P n increase was persistent and concomitant with an inhibition of respiration. However, during the days following the cold night, photosynthetic activity was decreased, and the cyclic electron flow was inhibited in Gewurtz., suggesting lower efficient energy dissipation. Likewise, metabolomic analysis revealed that several metabolites contents (namely alanine, GABA, lysine and succinate) were distinctly modulated in the two cultivars. Taking together, these results reflect a photosynthetic metabolism alteration or internal CO 2 conductance in Gewurtz. explaining partly why Pinot is less susceptible to cold stress.
Streptomyces anulatus S37 is an actinomycete able to colonize grapevine in-vitro plants and inhib... more Streptomyces anulatus S37 is an actinomycete able to colonize grapevine in-vitro plants and inhibit the growth of Botrytis cinerea. This strain has also a great potential to produce antifungal metabolites. These results indicate the potential of developing effective actinomycetes from Moroccan habitats for the biological control of B. cinerea. Further studies are ongoing to better understand the activity of each of the purified molecules.
Agronomy, 2013
The effectiveness of biological control agent, Ulocladium atrum (isolates U13 and U16) in protect... more The effectiveness of biological control agent, Ulocladium atrum (isolates U13 and U16) in protecting Vitis vinifera L. cv. Chardonnay against gray mold disease caused by Botrytis cinerea, and simulation of the foliar defense responses was investigated. A degraded mycelium structure during cultural assay on potato dextrose agar revealed that U. atrum isolates U13 and U16 were both antagonistic to B. cinerea, mainly when isolates were inoculated two days before Botrytis. Under in vitro conditions, foliar application of U. atrum protected grapevine leaves against gray mold disease. An increase in chitinase activity was induced by the presence of U. atrum isolates indicating that the biological control agents triggered plant defense mechanisms. Moreover, U13 has the potential to colonize the grapevine plantlets and to improve their growth. The ability of U. atrum isolates to exhibit an antagonistic effect against B. cinerea in addition to their aptitude to induce plant resistance and to promote grapevine growth may explain a part of their biological activity. Hence, this study suggests that U. atrum provides a suitable biocontrol agent against gray mold in grapevines.
Molecular Plant Pathology, 2014
Non-self-recognition of microorganisms partly relies on the perception of microbe-associated mole... more Non-self-recognition of microorganisms partly relies on the perception of microbe-associated molecular patterns (MAMPs) and leads to the activation of an innate immune response. Bacillus subtilis produces three main families of cyclic lipopeptides (LPs), namely surfactins, iturins and fengycins. Although LPs are involved in induced systemic resistance (ISR) activation, little is known about defence responses induced by these molecules and their involvement in local resistance to fungi. Here, we showed that purified surfactin, mycosubtilin (iturin family) and plipastatin (fengycin family) are perceived by grapevine plant cells. Although surfactin and mycosubtilin stimulated grapevine innate immune responses, they differentially activated early signalling pathways and defence gene expression. By contrast, plipastatin perception by grapevine cells only resulted in early signalling activation. Gene expression analysis suggested that mycosubtilin activated salicylic acid (SA) and jasmonic acid (JA) signalling pathways, whereas surfactin mainly induced an SA-regulated response. Although mycosubtilin and plipastatin displayed direct antifungal activity, only surfactin and mycosubtilin treatments resulted in a local long-lasting enhanced tolerance to the necrotrophic fungus Botrytis cinerea in grapevine leaves. Moreover, challenge with specific strains overproducing surfactin and mycosubtilin led to a slightly enhanced stimulation of the defence response compared with the LP-non-producing strain of B. subtilis. Altogether, our results provide the first comprehensive view of the involvement of LPs from B. subtilis in grapevine plant defence and local resistance against the necrotrophic pathogen Bo. cinerea. Moreover, this work is the first to highlight the ability of mycosubtilin to trigger an immune response in plants.
Physiologia Plantarum, 2014
Plant growth and survival depends critically on photo assimilates. Pathogen infection leads to ch... more Plant growth and survival depends critically on photo assimilates. Pathogen infection leads to changes in carbohydrate metabolism of plants. In this study, we monitored changes in the carbohydrate metabolism in the grapevine inflorescence and leaves using Botrytis cinerea and Botrytis pseudo cinerea. Fluctuations in gas exchange were correlated with variations in chlorophyll a fluorescence. During infection, the inflorescences showed an increase in net photosynthesis (Pn) with a stomatal limitation. In leaves, photosynthesis decreased, with a non-stomatal limitation. A decrease in the effective photosystem II (PSII) quantum yield (ΦPSII) was accompanied by an increase in photochemical quenching (qP) and non-photochemical quenching (qN). The enhancement of qP and ΦPSII could explain the observed increase in Pn. In leaves, the significant decline in ΦPSII and qP, and increase in qN suggest that energy was mostly oriented toward heat dissipation instead of CO 2 fixation. The accumulation of glucose and sucrose in inflorescences and glucose and fructose in the leaves during infection indicate that the plant's carbon metabolism is differently regulated in these two organs. While a strong accumulation of starch was observed at 24 and 48 hours post-inoculation (hpi) with both species of Botrytis in the inflorescences, a significant decrease with B. cinerea at 24 hpi and a significant increase with B. pseudo cinerea at 48 hpi were observed in the leaves. On the basis of these results, it can be said that during pathogen attack, the metabolism of grapevine inflorescence and leaf is modified suggesting distinct mechanisms modifying gas exchange, PSII activity and sugar contents in these two organs.
VirusDisease, 2014
Psorosis is a globally devastating disease of citrus caused by an infectious filamentous ophiovir... more Psorosis is a globally devastating disease of citrus caused by an infectious filamentous ophiovirus, Citrus psorosis virus (CPsV), which causes annual losses of about 5 % and a progressive decline of trees by affecting the conductive tissues. The disease can be harboured asymptomatically in many citrus species. In the field, the most characteristic symptoms of the disease in adult trees are bark scaling in the trunk and main branches and also internal staining in the underlying wood. The virus has a tripartite single-stranded RNA genome, and has been inadvertently spread to most citrus growing areas through the movement of citrus propagative material. No natural vectors have been identified except in limited citrus areas in some cases. Management strategies for CPsV involving shoot-tip grafting and thermotherapy or somatic embryogenesis from stigma and style cultures have been successfully used to eliminate CPsV from plant propagating material. Molecular pathogen-mediated strategies have been used to produce citrus plants. Such a strategy protects against infections by the virus from which the resistance gene and promising resistance may emerge from trials. Certification programs are among the best established means of increasing phytosanitary health, and some of those for citrus are among the oldest in the world. In conjunction with quarantine and clean stock programs, they remain important weapons in the ongoing fight against citrus diseases. One of the elements essential for successful certification programs to produce such propagation material is the availability of sensitive and effective diagnostic methods. In this review, we discuss an updated status of CPsV disease.
World Journal of Microbiology and Biotechnology, 2008
One hundred and forty-two different actinomycete strains were isolated from rhizosphere soil of V... more One hundred and forty-two different actinomycete strains were isolated from rhizosphere soil of Vitis vinifera L. sampled from four Moroccan areas. To evaluate the antifungal effect of the different collected actinomycete isolates, five fungi known to be phytopathogens (Pythium ultimum, Fusarium oxyysporum f. sp. albedinis, Sclerotium rolfsii, Verticillium dahliae and Botrytis cinerea) were used. Results showed that 24 isolates had
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Papers by Essaid Ait Barka