Search Results (13)

Olive anthracnose, caused by Colletotrichum fungi, and the olive fruit fly Bactrocera olea are, respectively, the most important fungal disease and pest affecting olive fruits worldwide, leading to detrimental effects on the yield and quality of fruits and olive oil. This study focuses on the content of hydroxytyrosol (HYT) and its derivatives (the “olive oil polyphenols” health claim) in olive oils extracted from fruits of ‘Galega Vulgar’ and ‘Cobrançosa’ cultivars, naturally affected by olive anthracnose and olive fly. The olives, with different damage levels, were harvested from organic rainfed orchards, located in the center of Portugal, at four harvest times over three years. Galega oils extracted from olives with a higher anthracnose and olive fly incidence showed no conformity for the extra virgin olive oil (EVOO) and virgin olive oil (VOO) categories, presenting high acidity and negative sensory notes accompanied by the disappearance of oleacein. Conversely, no sensory defects were observed in Cobrançosa oils, regardless of disease and pest incidence levels, and quality criteria were still in accordance with the EVOO category. The total HYT and tyrosol (TYR) content (>5 mg/20 g) allows for the use of the “olive oil polyphenols” health claim on the label of all the analyzed Cobrançosa olive oils. Full article

This study aimed to investigate the impact of Pulsed Electric Fields (PEF) technology in the extraction of olive oil on a pilot scale, using the “Galega Vulgar” olive variety as raw material. The extraction assisted by PEF had a malaxation time of 30 min and was compared with the traditional process of 45 min of malaxation. The main quality parameters of olive oil and the PEF’s cost-benefit assessment were performed. The incorporation of PEF in olive oil production reduced the malaxation stage by 33% without compromising the yield or extra-virgin classification. This efficiency leads to a potential 12.3% increase in annual olive oil production, with a 12.3% and 36.8% rise in revenue and gross profit, respectively. For small-scale production, the considerable upfront investment required for PEF equipment may be a challenge in terms of return on investment. In this scenario, opting for a renting scheme is the best economic solution, especially given the seasonal nature of olive oil production. In medium- to large-scale production, the investment in PEF is a sound investment since it is possible to achieve, with an equipment cost of EUR 450,000 and a production output of 5 tons per hour, an annual ROI of 20%. Full article

In olive trees, fluctuations in the onset of phenological stages have been reported due to weather conditions. The present study analyses the reproductive phenology of 17 olive cultivars grown in Elvas (Portugal) in 3 consecutive years (2012–2014). Through 2017–2022, the phenological observations continued with four cultivars. The phenological observations followed the BBCH scale. Over the course of the observations, the bud burst (stage 51) occurred gradually later; a few cultivars did not follow this trend in 2013. The flower cluster totally expanded phase (stage 55) was achieved gradually earlier, and the period between stages 51–55 was shortened, especially in 2014. Date of bud burst showed a negative correlation with minimum temperature (Tmin) of November–December, and, in ‘Arbequina’ and ‘Cobrançosa’, the interval stage 51–55 showed a negative correlation with both the Tmin of February and the Tmax of April, whereas in ‘Galega Vulgar’ and ‘Picual’ there was instead a positive correlation with the Tmin of March. These two seemed to be more responsive to early warm weather, whereas ‘Arbequina’ and ‘Cobrançosa’ were less sensitive. This investigation revealed that olive cultivars behaved differently under the same environmental conditions and, in some genotypes, the ecodormancy release may be linked to endogenous factors in a stronger way. Full article

The establishment of operation protocols for olive oil (OO) extraction at non-industrial scale is crucial for research purposes. Thus, the present study proposes a simple and cost-effective method for OO extraction at the laboratory scale (LS) level. To validate the proposed methodology, industrial OO extraction (IS) was performed in parallel, using the same cultivars ‘Galega vulgar’ (GV), ‘Cobrançosa’ (COB) and ‘Arbequina’ (ARB) collected from the same orchards, within the same period. Obtained results showed highest extractability for COB and ARB, of about 53%, while GAL showed 50%. All produced OO showed values lower than the regulated limits for the physicochemical parameters (acidity, K232, K268 and ΔK), classifying them as extra virgin OO (EVOO). Highest total phenolic content was observed for COB, with no significant differences (p-value > 0.05) between extraction methods. Regarding fatty acid composition, oleic acid (C18:1) showed the lowest percentage for ARB, with about 66% and 68%, for LS and IS, respectively, and the highest for GV with about 72% for both LS and IS. Furthermore, all samples from both extraction methods were compared to the European Community Regulation, with fatty acid composition within the regulated levels for EVOO. This work showed promising results regarding extraction yields and OO extractability, as well as its quality parameters. Full article

The valorisation of agro-industrial residues presents a challenge in obtaining economically sustainable and environmentally friendly industrial processes. Olive pomace is a by-product generated in large quantities, from olive oil extraction. This residue mostly consists of lignocellulosic materials. The aim of this study was to evaluate the potential use of extracted olive pomaces (EOP) obtained from olives with different ripening indexes (RI) and from different cultivars (Cobrançosa; RI = 2.5; 3.3 and 4.7; and Galega Vulgar; RI = 1.8; 2.9 and 4.8), to produce bioactive oligosaccharides from hemicelluloses by autohydrolysis. The hydrothermal treatment conditions were optimized by Response Surface Methodology, following a central composite rotatable design (CCRD), as a function of temperature (T: 142–198 °C) and time (t: 48–132 min), corresponding to severity factor (SF) values from 3.2 to 4.9. For all pomace samples, soluble sugar production was described by concave surfaces as a function of temperature and time. Autohydrolysis with SF equal or higher than 4.0 produced higher sugar yields, with maximum values around 180 g glucose equivalent/kg EOP for SF of 4.7 (190 °C/120 min) or 4.9 (198 °C/90 min). These values were similar for both cultivars and were not dependent on the ripening stage of the olives. Maximum oligosaccharide (OS) yields of 98% were obtained by autohydrolysis with SF of 4.0. The increase in SF to 4.9 resulted in a decrease in OS yield to 86–92%, due to the release of monomeric sugars. The monosaccharides were mostly xylose (55.8–67.7% in Galega; 50.4–69.0% in Cobrançosa liquid phases), and glucose, galactose, arabinose and rhamnose, in smaller quantities. Therefore, the production of bioactive xylo-oligosaccharides (XOS) from olive pomaces mainly depends on the hydrothermal conditions used. Full article

Anthracnose is the most important disease of olives responsible for olive oil depreciation. The aim of this study is to compare the negative effects of the most common olive anthracnose pathogens in Portugal, Colletotrichum nymphaeae, C. godetiae, or C. acutatum, on oil extracted from fruits of the most cultivated Portuguese olive cultivars, ‘Galega Vulgar’ and ‘Cobrançosa’. Healthy fruits (ripening index 3.5) were inoculated, incubated, and sampled over 14 days post-inoculation (d.p.i.) for symptom assessment and oil extraction. Virgin olive oil (VOO) was characterised by quality criteria parameters (acidity, peroxide value, UV absorbances, organoleptic assessment, fatty acid ethyl esters (FAEE)), total phenols (TPH), main fatty acids, and waxes compositions. Galega Vulgar fruits were more susceptible to anthracnose than Cobrançosa fruits. Colletotrichum nymphaeae was equally highly virulent for both cultivars, while C. godetiae was less virulent especially in Cobrançosa. VOO acidity increased reached 5% in Galega oils and 2% in Cobrançosa oils from fruits infected with C. nymphaeae or C. acutatum at 14 d.p.i. FAEE were higher than the legal limit for extra VOO in Galega oils from fruits at 7 d.p.i. with C. nymphaeae or C. acutatum, or 11 d.p.i. with C. godetiae. TPH decreased through the experiments with all the inoculated fungi. The musty sensory defect was detected in Galega and Cobrançosa VOO from fruits inoculated with C. nymphaeae or C. acutatum at 3 or 7 d.p.i. earlier than chemical degradation, respectively. The degradation levels of olive oils depended on the Colletotrichum species and olive cultivar. Full article

Several olive cultivars, characterized by high-quality olive oil show agronomical issues such as excessive vigor, high susceptibility to biotic and abiotic stresses, and low propagation ability. They are strong candidates for breeding based on new technologies to improve their performance in a short period of time. For this reason, the first step is developing efficient somatic embryogenesis (SE) protocols. Somatic embryogenesis in olive is highly genotype-dependent for both adult tissues and mature embryos as initial explants, requiring the development of specific protocols for each genotype. Trials using cotyledons and radicles as initial explants, isolated from ripe seeds from the Portuguese olive cv. ‘Galega vulgar’, gave more than 95% calli development. Radicles proved to be the most responsive tissue for SE induction, with an average of 2 embryos per callus after callus transfer to expression medium, and 14 embryos per callus after subculture on the olive cyclic embryogenesis medium (ECO). Embryogenic competence could be recovered after several subcultures on ECO medium that maintained cyclic embryogenesis for an indeterminate period of time. Embryo conversion and plant acclimatization were also attained with high success rates. Media management for cyclic embryogenesis maintenance is of general importance for SE protocols in any olive genotype. Somatic embryogenesis was thus attained for the first time in embryo-derived explants of cv. ‘Galega vulgar’. Full article

The phenolic composition of olive fruits represents a vast and unique source of health beneficial molecules due to the presence of specific phenolic compounds (PCs), such as verbascoside (VERB), oleuropein (OLE) and its derivative molecules. Despite of being some of the most critical compounds regarding olive oil quality, these PCs are mostly abundant in olive fruits and leafs due to their hydrophilic nature. In olives, the phenolic profile suffers a deep and constant change along fruit ripening being the phenolic alcohols, such as hydroxytyrosol (HT), mainly formed by OLE, and/or OLE aglycone molecules degradation. The present work aims to study the maturation evolution of olive fruits from two major traditional Portuguese cultivars, ‘Galega Vulgar’ and ‘Cobrançosa’, in regard to their specific phenolic profile, as well as caliber (C), moisture (H), fat content in dry matter (OPDW) and maturity index (MI). Results show that both cultivars present distinct phenolic profiles along their ripening, with ‘Galega Vulgar’ reaching a high MI and OPDW at a much earlier ripening stage (S3), in agreement with the moment when a maximum OLE accumulation was registered. On the other hand, ‘Cobrançosa’ cultivar reached its higher MI and OPDW at S6 (harvest period), coinciding also with high OLE concentrations. MI may be used as a prediction tool for ’Galega Vulgar’ optimal harvesting time evaluation, associated with higher OLE and VERB concentrations, which will confer an additional protection towards diseases, that normally affect olive orchards. Full article

Exogenous auxins supplementation plays a central role in the formation of adventitious roots (AR) for several plant species. However, the molecular mechanisms underlying the process of adventitious rooting are still not completely understood and many plants with economic value, including several olive cultivars, exhibit a recalcitrant behavior towards cutting propagation, which limits its availability in plant nurseries. PIN-formed proteins are auxin efflux transporters that have been widely characterized in several plant species due to their involvement in many developmental processes including root formation. The present study profiled the expression of the OePIN1a-c, OePIN2b, OePIN3a-c, OePIN5a-c, OePIN6, and OePIN8 gene members during indole-3-butyric acid (IBA)-induced in vitro adventitious rooting using the olive cultivar ‘Galega vulgar’. Gene expression analysis by quantitative real time PCR (RT-qPCR) showed drastic downregulation of most transcripts, just a few hours after explant inoculation, in both nontreated and IBA-treated microcuttings, albeit gene downregulation was less pronounced in IBA-treated stems. In contrast, OePIN2b showed a distinct expression pattern being upregulated in both conditions, and OePIN5b was highly upregulated in IBA-induced stems. All transcripts, except OePIN8, showed different expression profiles between nontreated and IBA-treated explants throughout the rooting experiment. Additionally, high levels of reactive oxygen species (ROS) were observed soon after explant preparation, decreasing a few hours after inoculation. Altogether, the results suggest that wounding-related ROS production, associated with explant preparation for rooting, may have an impact on auxin transport and distribution via changes in OePIN gene expression. Moreover, the application of exogenous auxin may modulate auxin homeostasis through regulation of those genes, leading to auxin redistribution throughout the stem-base tissue, which may ultimately play an important role in AR formation. Full article

In this study, the presence and variability of Colletotrichum spp. was evaluated by comparing fungal isolates obtained from olive trees under long-time phytosanitary treatments with trees without any phytosanitary treatments (treated and untreated, respectively). Olive fruits of trees of the highly susceptible ‘Galega vulgar’ cultivar growing in the Alentejo region were used as samples. From the 210 olive trees sampled (half from treated and half from untreated orchards), 125 (59.5%) presented Colletotrichum spp., with a significant lower number of infected trees in treated (39) when compared to untreated orchards (86). The alignment and analysis of beta-tubulin (tub2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), chitin synthase (CHS-1) and histone H3 (HIS-3) gene sequences allowed the identification of all 125 isolates as belonging to the C. acutatum complex. The vast majority of the isolates (124) were identified as C. nymphaeae and one isolate, from an untreated tree, was identified as C. godetiae. Isolates were divided into five different groups: Group A: 39 isolates from treated trees matched in 100% with C. nymphaeae sequences from the database; Group B: 76 isolates from untreated trees matched in 100% with C. nymphaeae sequences from the database; Group C: one isolate from untreated trees presenting a single nucleotidic difference in the HIS-3 sequence; Group D: eight isolates from untreated trees presenting differences in two nucleotides in the tub2 sequences that changed the protein structure, together with differences in two specific nucleotides of the GAPDH sequences; Group E: one isolate, from untreated olive trees, matched 100% with C. godetiae sequences from the database in all genes. Considering the similarities of the sampled areas, our results show that the long-time application of fungicides may have caused a reduction in the number of olive trees infected with Colletotrichum spp. but an increase in the number of fruits positive to Colletotrichum spp. within each tree, which may suggest different degrees of virulence of Colletotrichum isolates from trees growing different management regimes. It is imperative that the fungicides described as causing resistance are applied at appropriate times and intervals, since their efficiency decreases when applied incorrectly and new and more virulent species may arise. Full article

Venturia oleaginea and Pseudocercospora cladosporioides are two of the most important olive fungal pathogens causing leaf spots: peacock spot, and cercosporiosis, respectively. In the present study, fungal communities associated with the presence of these pathogens were investigated. Overall, 300 symptomatic and asymptomatic trees from different cultivars were sampled from Alentejo, Portugal. A total of 788 fungal isolates were obtained and classified into 21 OTUs; Ascomycota was clearly the predominant phylum (96.6%). Trees from cultivar ‘Galega vulgar’ showed a significant higher fungal richness when compared to ‘Cobrançosa’, which in turn showed significant higher values than ‘Picual’. Concerning plant health status, symptomatic plants showed significant higher fungal richness, mainly due to the high number of isolates of the pathogens V. oleaginea and P. cladosporioides. In terms of fungal diversity, there were two major groups: ca. 90% of the isolates found in symptomatic plants belonged to V. oleaginea, P. cladosporioides, Chalara sp., and Foliophoma sp. while ca. 90% of the isolates found in asymptomatic plants, belonged to Alternaria sp. and Epicoccum sp. This study highlights the existence of different fungal communities in olive trees, including potential antagonistic organisms that can have a significant impact on diseases and consequently on olive production. Full article

Olive anthracnose is a very common and severe disease caused by diverse species of fungi belonging to Colletotrichum acutatum and Colletotrichum gloeosporioides complexes. To understand aspects of the Colletotrichum colonization and primary infection in olives, Colletotrichum spp. were isolated from the interior of 2-year stems, flower buds, and immature fruits of three important olive cultivars, Galega vulgar, Cobrançosa, and Azeiteira, from different sites within Alentejo, a major olive-producing region in Portugal. A total of 270 trees was sampled, and 68 Colletotrichum spp. isolates were obtained from 46 olive trees. DNA extraction and amplification of β-tubulin and GADPH genes through PCR revealed that the vast majority of the isolates showed high similarity to Colletotrichum nymphaeae, and only three isolates showed high similarity to Colletotrichum godetiae. The highest number of Colletotrichum spp. isolates was detected in olive trees from Galega vulgar and in immature fruits. No significant differences in the number of Colletotrichum spp. isolates were found in trees from different sites. The highest percentages of infected immature fruits were obtained in trees that also presented a high percentage of 2-year stem infections, which may indicate that 2-year stems serve as important sources of inoculum, and the fungus may travel from the stems to other parts of the plant. Another indication of such possibility is that one isolate of C. nymphaeae (C. nymphaeae 2), characterized by a unique nucleotide mutation within the beta tubulin gene, was present in different organs of the same tree, both in 2-year stems and in recently formed vegetative organs as flower buds and immature fruits, which seem to suggest that it may be the same isolate, which has moved systemically inside the plant. The results presented here can play an important role in working out strategies for the effective and timely management of the disease and in reducing the number of unnecessary fungicide applications. Full article

Propagation of some Olea europaea L. cultivars is strongly limited due to recalcitrant behavior in adventitious root formation by semi-hardwood cuttings. One example is the cultivar ”Galega vulgar”. The formation of adventitious roots is considered a morphological response to stress. Alternative oxidase (AOX) is the terminal oxidase of the alternative pathway of the plant mitochondrial electron transport chain. This enzyme is well known to be induced in response to several biotic and abiotic stress situations. This work aimed to characterize the alternative oxidase 1 (AOX1)-subfamily in olive and to analyze the expression of transcripts during the indole-3-butyric acid (IBA)-induced in vitro adventitious rooting (AR) process. OeAOX1a (acc. no. MF410318) and OeAOX1d (acc. no. MF410319) were identified, as well as different transcript variants for both genes which resulted from alternative polyadenylation events. A correlation between transcript accumulation of both OeAOX1a and OeAOX1d transcripts and the three distinct phases (induction, initiation, and expression) of the AR process in olive was observed. Olive AOX1 genes seem to be associated with the induction and development of adventitious roots in IBA-treated explants. A better understanding of the molecular mechanisms underlying the stimulus needed for the induction of adventitious roots may help to develop more targeted and effective rooting induction protocols in order to improve the rooting ability of difficult-to-root cultivars. Full article