Search Results (13)

Pythium schmitthenneri, a soilborne pathogen responsible for root rot in olive trees, poses a significant threat to olive production. Managing this pathogen remains challenging due to its aggressive root colonization and the limited efficacy of conventional control methods. Given the concerns associated with chemical treatments, this study evaluated the resistance of eight olive varieties to P. schmitthenneri-induced root rot under controlled greenhouse conditions by assessing structural and biochemical defense mechanisms. Greenhouse trials revealed that Arbequina, Koroneiki, and Haouziya exhibited strong resistance, with 0% disease severity, while Picholine Marocaine and Picholine Languedoc were highly susceptible, reaching 100% disease severity. Growth parameters varied significantly, with susceptible varieties showing severe reductions in root length (RL), root fresh weight (RFW), and root dry weight (RDW), whereas resistant varieties maintained these parameters unchanged. While shoot length (SL) remained unaffected across all varieties, shoot fresh weight (SFW) and shoot dry weight (SDW) were significantly reduced in susceptible ones. Fourier-transform infrared (FTIR) spectroscopy revealed that resistant varieties maintained stable levels of lignin, cellulose, and polysaccharides, while susceptible ones exhibited extensive cell wall degradation. Additionally, total polyphenol content (TPC) and total flavonoid content (TFC) significantly increased in resistant varieties upon infection, whereas susceptible varieties experienced a substantial decline. These findings highlight the crucial role of structural and biochemical defenses in olive resistance to P. schmitthenneri and suggest that selecting resistant varieties could serve as a sustainable strategy for managing root rot in olive production. Full article

The goal of this study was to determine the composition of olive oils from four North Moroccan provinces (Larache, Chefchaouen, Ouazzane and Tetouan), one of the main productive zones nationwide. For this purpose, we evaluate the quality parameters, phenolic compounds, oxidative stability, fatty acids, sterols, uvaol + erytrodiol, carotenoids and chlorophylls of three varieties (‘Picholine marocaine’, ‘Haouzia’ and ‘Menara’) in three campaigns (2019/2020 to 2021/2022) and in three harvesting periods. Another aim was to research the effect of natural microtalc (NMT) on the compounds of olive oils, and to evaluate whether the addition of microtalc to olive pastes during the malaxation stage influences in the quality of olive oils. From the results, it was observed that industrial yields increase when natural microtalcs were used during the oil production. Considering the quality parameters, the olive oils produced with NMT showed lower values when compared with those obtained without any addition. Also, oils produced with NMT showed a higher content in phenolic compounds as well as a greater oxidative stability. It is worth highlighting that the maximum content in phenolic compounds, adding NMT during the extraction process, was determined in oils obtained from the ‘Picholine marocaine’ variety from Chefchaouen, harvested in the 2019/2020 campaign, with 848.71 mg/kg oil, with a value of oxidative stability of 78.68 h. Full article

The olive tree is one of the most important fruit crops grown in Morocco, yet extensive decline associated with the root rot of this crop has been observed in many regions. This study aimed to identify and characterize the oomycetes associated with root rot disease in olive trees. During the 2021 and 2022 growing seasons, symptomatic root tissues and soil samples were collected for isolation. Based on morphological traits and the sequencing of the internal transcribed spacer (ITS) region of rDNA, 10 oomycete species were identified, belonging to the Phytophthora and Pythium sensu lato (s.l.) genera. Seven species were assigned to Phytophthora, namely, P. palmivora, P. plurivora, P. acerina, P. oleae, P. cactorum, P. gonapodyides, and P. megasperma. The Pythium s.l. genus was represented by three species, including P. schmitthenneri, P. aphanidermatum, and P. irregulare. A pathogenicity assay was conducted by soil infestation to evaluate the effect of these pathogens on one-year-old olive saplings (var. Picholine Marocaine). Results revealed that all 10 species were pathogenic to olive saplings. Inoculated saplings exhibited symptoms, such as root rot, vascular discoloration, and wilting. The pathogens were successfully re-isolated from necrotic roots, thereby fulfilling Koch’s postulates. These findings highlight the complex etiology of root rot disease in olive trees, as multiple species can induce similar symptoms. This study represents the first detailed report of Phytophthora and Pythium s.l. species associated with olive root rot disease in Morocco. Full article

Verticillium wilt of olive (VWO), caused by Verticillium dahliae (Vd), represents a significant threat to olive cultivation, particularly to the Moroccan cultivar “Picholine Marocaine”, by reducing yield, tree survival, and overall productivity. Current chemical and cultural control strategies provide limited efficacy, highlighting the need for alternative approaches such as biological control. This study investigated the potential of Rhizophagus irregularis (RI) as a biological agent to mitigate VWO over a 10-month period following V. dahliae inoculation. Disease severity, incidence, and defoliation rate as well as oxidant stress markers, antioxidant enzyme activities, and the phenolic pathway were evaluated in a greenhouse experiment. Our results showed that R. irregularis significantly reduced (p < 0.05) disease severity and incidence by about 31% and 26%, respectively, and decreased defoliation rates by 35% in RI-infected plants (RIV). The presence of R. irregularis triggered enhanced antioxidant enzyme activities (e.g., superoxide dismutase, catalase, and polyphenoloxidase), increased lignin deposition, elevated phenylalanine ammonia-lyase activity, and increased total phenol content in olive tissues. These biochemical and structural changes reduced lipid peroxidation, oxidative stress, and physiological damage, resulting in delayed disease progression. Enhanced accumulation of lignin and total phenolic compounds, particularly in aboveground tissues, was observed. This likely reinforced cell walls and enhanced resistance to pathogen infection. This study demonstrates that R. irregularis offers a promising biocontrol agent for combating soil-borne diseases in olives and other susceptible crops by mitigating VWO, boosting antioxidant defenses, and modulating the phenolic pathway with tissue-specific responses. Full article

This study explores the potential of olive leaves, long integral to Mediterranean traditional medicine, as a rich source of valuable compounds. The challenge lies in their considerable water content, hindering these compounds’ full valorization. Four drying methods (air-drying, oven-drying, freeze-drying and solar-drying) were investigated for their impact on nutrient and bioactive compound content in the leaves of four olive varieties (“Arbequina”, “Koroneiki”, “Menara” and “Picholine Marocaine”) cultivated in Morocco. In their fresh state, “Picholine Marocaine” exhibited the highest protein levels (6.11%), “Arbequina” had the highest phenolic content (20.18 mg gallic acid equivalents/g fresh weight (FW)), and “Koroneiki” and “Menara” were highest in flavonoids (3.28 mg quercetin equivalents/g FW). Specific drying methods proved optimal for different varieties. Oven-drying at 60 °C and 70 °C effectively preserved protein, while phenolic content varied with drying conditions. Air-drying and freeze-drying demonstrated effectiveness for flavonoids. In addition, an analytical approach using high-performance liquid chromatography and diode array detection (HPLC-DAD) was applied to investigate the effects of the different drying methods on the bioactive fraction of the analyzed samples. The results showed qualitative and quantitative differences depending on both the variety and the drying method used. A total of 11 phenolic compounds were tentatively identified, with oleuropein being the most abundant in all the samples analyzed. The freeze-dried samples showed the highest content of oleuropein in the varieties “Arbequina” and “Picholine Marocaine” compared to the other methods analyzed. In contrast, “Koroneiki” and “Menara” had higher oleuropein content when air dried. Overall, the obtained results highlight the importance of tailored drying techniques for the preservation of nutrients and bioactive compounds in olive leaves. Full article

Delineating chilling and forcing periods is one of the challenging topics in understanding how temperatures drive the timing of budburst and bloom in fruit tree species. Here, we investigated this question on olive trees, using flowering data collected over six years on 331 cultivars in the worldwide collection of Marrakech, Morocco. Using a Partial Least Squares approach on a long-term phenology (29 years) of ‘Picholine Marocaine’ cultivar, we showed that the relevance of delineating the chilling and forcing periods depends more on the variability of inter-annual temperatures than on the long-term datasets. In fact, chilling and forcing periods are similar between those delineated by using datasets of 29 years and those of only 6 years (2014–2019). We demonstrated that the variability of inter-annual temperatures is the main factor explaining this pattern. We then used the datasets of six years to assess the chill and heat requirements of 285 cultivars. We classified Mediterranean olive cultivars into four groups according to their chill requirements. Our results, using the Kriging interpolation method, indicated that flowering dates of most of these cultivars (92%) were governed by both chilling and forcing temperatures. Our investigations provided first insights to select adapted cultivars to global warming. Full article

This work investigates the relationships between leaf traits and olive response to water stress through two complementary field experiments in order to screen genotypes for drought tolerance. The first experiment consisted of the phenotyping of 32 olive varieties for 11 leaf morpho-physiological traits during a fruit set phase under well-watered conditions. In the second experiment, the yield and vegetative responses of five representative varieties to the withholding of irrigation during the whole fruit growth period were assessed to identify leaf traits that are associated with olive resilience plasticity and that could be used as drought tolerance markers. The results highlighted large phenotypic variability for leaf area (LA, 2.9–9.5 cm²), petiole elasticity (8.0–36.0°), water loss in detached leaves (WLDL, 3.6–11.6%), stomatal density (222.6–470.1 no mm⁻²), stomatal length (11.4–18.7 µm), trichome density (120.5–204.4 no mm⁻²), trichome width (103.6–183.4 µm), leaf contents in cuticular wax (CWC, 44.7–606.2 µg cm⁻²), and soluble sugars (SSC, 15.8–536.9 mg g_dw⁻¹). Among these leaf traits, WLDL displayed a significant correlation with the yield stability index (r = −0.973) and water use efficiency (r = −0.939), suggesting its use as relevant drought tolerance phenotypic marker. Likewise, LA, SSC, and CWC were singled out as second-level drought tolerance markers, being strongly correlated with stability of leaf size and leafing intensity in response to water stress. Cluster analysis highlighted 12 distinct levels of drought tolerance within the studied olive collection. Based on the four identified phenotypic markers, “Lechin de Sevilla” alongside “Picholine Marocaine” were found to be the most drought-tolerant varieties, while Frantoio was the most sensitive. This study provides the first, unprecedented, insights into the usefulness of leaf phenotyping in olive drought tolerance screening, with a focus on structural and functional leaf traits. Full article

The volatile profile of an olive oil is a crucial attribute indicating its sensory quality. Hence, to elucidate the impact of geographical origin (including edaphoclimatic conditions) and the crop season on the volatile composition of monovarietal Moroccan olive oil “Picholine Marocaine”, over a two-year harvest period (2018/19 and 2019/20), thirty-eight olive oil samples were obtained from nineteen Moroccan areas well-known by the abundance of olive tree cultivation. By using SPME/GC-FID-MS, 229 and 215 volatile compounds were characterized in olive oils produced during the 2018/19 and 2019/20 crop years, respectively. The identified compounds belong to nine volatile groups: terpenes, hydrocarbons, furans, esters, alcohols, acids, ketones, aldehydes, and nitrogen compounds. The one-way ANOVA and interactive heatmap revealed significant differences in the volatiles proportion in oils from different geographical origins. Our results imply that environmental (edaphoclimatic) conditions considerably influence the volatile compounds’ biosynthesis, e.g., when soil granulometry decreases (from sand to silt), alcohols become esters due to the activity of alcohol dehydrogenase (ADH) and alcohol acetyl transferase (AAT) enzymes. Moreover, our findings exhibit a significant influence of the crop season on the volatile composition of Moroccan olive oils. Full article

Morocco belongs to the countries ranked at a high-risk level for entry, establishment, and spread of Xylella fastidiosa, which has recently re-emerged as a plant pathogen of global importance causing olive quick decline syndrome (OQDS). Symptomatic infection by X. fastidiosa leads to devastating diseases and important economic losses. To prevent such losses and damages, countries without current outbreaks like Morocco need to first understand their host plant responses to X. fastidiosa. The assessment of the macro and micro-elements content (ionome) in leaves can give basic and useful information along with being a powerful tool for the sustainable management of diseases caused by this devastating pathogen. Herein, we compare the leaf ionome of four important autochthonous Moroccan olive cultivars (‘Picholine Marocaine’, ‘Haouzia’, ‘Menara’, and ‘Meslalla’), and eight Mediterranean varieties introduced in Morocco (‘Arbequina’, ‘Arbosana’, ‘Leccino’, ‘Ogliarola salentina’, ‘Cellina di Nardo’, ‘Frantoio’, ‘Leucocarpa’, and ‘Picholine de Languedoc’), to develop hypotheses related to the resistance or susceptibility of the Moroccan olive trees to X. fastidiosa infection. Leaf ionomes, mainly Ca, Cu, Fe, Mg, Mn, Na, Zn, and P, were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). These varieties were also screened for their total phenolics and flavonoids content. Data were then involved in a comparative scheme to determine the plasticity of the pathogen. Our results showed that the varieties ‘Leccino’, ’Arbosana’, ‘Arbequina’ consistently contained higher Mn, Cu, and Zn and lower Ca and Na levels compared with the higher pathogen-sensitive ‘Ogliarola salentina’ and ‘Cellina di Nardò’. Our findings suggest that ‘Arbozana’, ‘Arbiquina’, ‘Menara’, and ‘Haouzia’ may tolerate the infection by X. fastidiosa to varying degrees, provides additional support for ‘Leccino’ having resistance to X. fastidiosa, and suggests that both ‘Ogliarola salentina’ and ‘Cellina di Nardö’ are likely sensitive to X. fastidiosa infection. Full article

As part of the search for biochemical markers of somatic embryogenesis in tissue cultures of olive (Olea europaea L.), peroxidases (POXs) in both the soluble and ionically wall-bound fractions were studied in two reputed olive cultivars (cvs.): “Picholine Marocaine” and “Dahbia”. In order to carry out embryogenesis induction, proximal cotyledons were cultured in modified olive medium (OMc) supplemented with 25 μM indole-3-butylic acid (IBA) and 2.5 μM 2-isopentenyladenine (2iP), while distal leaf fragments (somatic explants) were cultured in OMc supplemented with 4.56 µM zeatin riboside (ZR) and 10.25 µM 1-naphthaleneacetic acid (NAA). Regarding embryogenic potentials, the zygotic explants (cv. Picholine Marocaine: 43.39%; cv. Dahbia: 53.41%) were more regenerative than the somatic explants (cv. Picholine Marocaine: 13.05%; cv. Dahbia: 19.51%). The enzyme assay showed a higher POX activity in embryogenic calluses (ECs) than in nonembryogenic calluses (NECs) for the zygotic explants in both studied cultivars. When expressed as units per milligram of proteins (U mg⁻¹ proteins), the highest total POXs activities (soluble POXs + ionically wall-bound POXs) were found in the ECs derived from the zygotic explants; for cv. Dahbia, 65% of the enzyme activities came from the ionically wall-bound fractions. Polyacrylamide gel electrophoresis showed that the ECs of the highly active cv. Dahbia were characterized by highly active isoperoxidases that were revealed in four migration zones, particularly a doublet in the A4 zone (R_f 0.70–0.73) present in the ionically wall-bound POXs. The fast-moving anodic POXs of the ionically wall-bound fractions could be adopted as an early electrophoretic test to determine the embryogenesis capacities in olive tissue culture materials. As biochemical markers, the POX enzyme and its profile in fractions, i.e., as soluble POXs and ionically wall-bound POXs, can offer a valuable tool for improving the tissue culture of olive via somatic embryogenesis. Full article

Olive oil is an important product in the Mediterranean diet, due to its health benefits and sensorial characteristics. Picholine marocaine is the most cultivated variety in Morocco. The present research aims to evaluate the phenolic compounds, vitamin E and fatty acids of commercial Picholine marocaine virgin olive oils (VOOs) from five different North Moroccan provinces (Chefchaouen, Taounate, Errachidia, Beni Mellal and Taza), using HPLC-photodiode array (PDA)/electrospray ionization (ESI)-MS, normal phase (NP)-HPLC/ fluorescence detector (FLD) and GC-flame ionization detector (FID)/MS, respectively. The obtained results showed an average content of 130.0 mg kg⁻¹ of secoiridoids (oleuropein aglycone, 10-hydroxy-oleuropein aglycone and ligstroside aglycone, oleocanthal and oleacein), 108.1 mg kg⁻¹ of phenolic alcohols (tyrosol and hydroxytyrosol), 34.7 mg kg⁻¹ of phenolic acids (caffeic acid, ferulic acid and elenolic acid), and 8.24 mg kg⁻¹ of flavonoids (luteolin, luteolin glucoside, apigenin). With regard to vitamin E, α-tocopherol was the most abundant vitamin E (57.9 mg kg⁻¹), followed by α-tocotrienol (2.5 mg kg⁻¹), γ-tocopherol (4.5 mg kg⁻¹) and β-tocopherol (1.9 mg kg⁻¹), while δ-tocopherol was not detected. Moreover, 14 fatty acids were found and, among them, oleic acid (76.1%), linoleic acid (8.1%) palmitic acid (8.7%) and stearic acid (2.5%) were the major fatty acids detected. Finally, heat map and principal component analysis allowed us to classify the studied provinces in terms of VOO chemical composition: Chefchaouen (tyrosol and hydroxytyrosol), Taounate (oleuropein aglycone), Errachidia (ferulic acid, w-3 and w-6), Beni Mellal (oleocanthal) and Taza (luteolin and oleic acid). Full article

In Morocco, the recovery of olive agro-industrial by-products as potential sources of high-added value substances has been underestimated so far. A comprehensive quantitative characterization of olive leaves’ bioactive compounds is crucial for any attempt to change this situation and to implement the valorization concept in emerging countries. Thus, the phenolic fraction of olive leaves of 11 varieties (‘Arbequina’, ‘Hojiblanca’, ‘Frantoio’, ‘Koroneiki’, ‘Lechín’, ‘Lucque’, ‘Manzanilla’, ‘Picholine de Languedoc’, ‘Picholine Marocaine’, ‘Picual’ and ‘Verdal’), cultivated in the Moroccan Meknès region, was investigated. Thirty eight phenolic or related compounds (including 16 secoiridoids, nine flavonoids in their aglycone form, seven flavonoids in glycosylated form, four simple phenols, one phenolic acid and one lignan) were determined in a total of 55 samples by using ultrasonic-assisted extraction and liquid chromatography coupled to electrospray ionization-ion trap mass spectrometry (LC-ESI-IT MS). Very remarkable quantitative differences were observed among the profiles of the studied cultivars. ‘Picholine Marocaine’ variety exhibited the highest total phenolic content (around 44 g/kg dry weight (DW)), and logically showed the highest concentration in terms of various individual compounds. In addition, chemometrics (principal components analysis (PCA) and stepwise-linear discriminant analysis (s-LDA)) were applied to the quantitative phenolic compound data, allowing good discrimination of the selected samples according to their varietal origin. Full article

Olive oil phenolic fraction considerably contributes to the sensory quality and nutritional value of this foodstuff. Herein, the phenolic fraction of 203 olive oil samples extracted from fruits of four autochthonous Moroccan cultivars (“Picholine Marocaine”, “Dahbia”, “Haouzia” and “Menara”), and nine Mediterranean varieties recently introduced in Morocco (“Arbequina”, “Arbosana”, “Cornicabra”, “Frantoio”, “Hojiblanca”, “Koroneiki”, “Manzanilla”, “Picholine de Languedoc” and “Picual”), were explored over two consecutive crop seasons (2012/2013 and 2013/2014) by using liquid chromatography-mass spectrometry. A total of 32 phenolic compounds (and quinic acid), belonging to five chemical classes (secoiridoids, simple phenols, flavonoids, lignans and phenolic acids) were identified and quantified. Phenolic profiling revealed that the determined phenolic compounds showed variety-dependent levels, being, at the same time, significantly affected by the crop season. Moreover, based on the obtained phenolic composition and chemometric linear discriminant analysis, statistical models were obtained allowing a very satisfactory classification and prediction of the varietal origin of the studied oils. Full article