Wild Olive Research Articles

Genome Wide MeDIP-Seq Profiling of Wild and Cultivated Olives Trees Suggests DNA Methylation Fingerprint on the Sensory Quality of Olive Oil.

Secondary metabolites are particularly important to humans due to their pharmaceutical properties. Moreover, secondary metabolites are key compounds in climate change adaptation in long-living trees. Recently, it has been described that the domestication of Olea subspecies had no major selection signature on coding variants and was mainly related to changes in gene expression. In addition, the phenotypic plasticity in Olea subspecies was linked to the activation of transposable elements in the genes neighboring. Here, we investigated the imprint of DNA methylation in the unassigned fraction of the phenotypic plasticity of the Olea subspecies, using methylated DNA immuno-precipitation sequencing (MeDIP-seq) for a high-resolution genome-wide DNA methylation profiling of leaves and fruits during fruit development in wild and cultivated olives from Turkey. Notably, the methylation profiling showed a differential DNA methylation in secondary metabolism responsible for the sensory quality of olive oil. Here, we highlight for the first time the imprint of DNA methylation in modulating the activity of the Linoleate 9S lipoxygenase in the biosynthesis of volatile aromatic compounds. Unprecedently, the current study reveals the methylation status of the olive genome during fruit ripening.

Resisting Aridification: Adaptation of Sap Conduction Performance in Moroccan Wild Olive Subspecies Distributed Over an Aridity Gradient.

In the current context of global change, the increasing frequency and the length of drought periods are testing the resistance capacities of plants of dry habitats. However, although the adaptation of plants to drought has been widely studied, the anatomical features of wood influencing the functional responses of plants to drought are still lacking at the intraspecific level, especially for species with a wide geographical distribution. As a result, we have studied the variation of wood anatomical traits related to sap conduction (i.e., vessel surface area, vessel density, and number of vessels joined by radial file) in two wild olive subspecies distributed in Morocco (i.e., Olea europaea subsp. europaea. var. sylvestris and Olea europaea subsp. maroccana), in relation to various drought conditions. This functional study, based on wood trait measurements of 351 samples from 130 trees and 13 populations, explores potential sap conduction in relation to environmental parameters and as a result, strategies to resist water stress. We found that (1) branch diameter (BD) captured 78% of total wood trait variation, (2) vessel size (SVS) expressed 32% of intraspecific variation according to cambium age, and (3) the positive relationship between SVS and BD could be explained by climate type, vegetation cover changes, and therefore available water resources. Taking into consideration the diameter of the branch as the main factor of anatomical variation, established reaction norms (linear models) at the intrapopulation scale of vessel lumen area according to aridity show for the first time how the functioning of the cambium modulates and controls sap conduction, according to aridity and thus available water resources. They pinpoint the risks incurred by the wild olive tree in the perspective of a dramatic increase in aridity, in particular, the inability of the cambium to produce large enough vessels to efficiently transport sap and irrigate the leaves. Finally, this study opens new and interesting avenues for studying at a Mediterranean scale, the resistance and the vulnerability of wild forms and cultivated varieties of olive to heterogeneous and changing environmental conditions.

Identification of the most preferred topographic elevation characteristics for the wild olive trees in Al-Baha Region, Saudi Arabia

The aim of this research was to identify the topographical elevation characteristics most preferred by wild olive trees in the Al-Baha region. This study successfully identified the elevation preferred by wild olives. The results show that the majority (81.6%) of wild olives are located at an elevation range of 1,750–2,500m. However, in the Al-Mandaq sub-region, many wild olive trees can also be found at a lower elevation of 1,250–1,500m, while wild olive presence at a higher elevation of 2000–2,500m can be found in the Al-Baha sub-region. It was observed that at a lower elevation of 1500–1750m, most wild olive crown sizes are small, indicating that the wild olive prefers a higher elevation to grow well. These findings can be regarded as theoretically indicating landforms suitable for olive plantation. As a basis for the suitability of olive plantation sites, these topographical characteristics factors are the essential prerequisites. However, it is obvious that site suitability is subject to the temporal dynamics of environmental variables.

Wild Olive Genotypes as a Valuable Source of Resistance to Defoliating Verticillium dahliae.

Resistance to the defoliating pathotype of Verticillium dahliae has been evaluated in a pool of 68 wild genotypes of olive belonging to the SILVOLIVE collection. Resistance was evaluated by assessing symptom severity using a 0–4 rating scale, estimating the relative area under the disease progress curve (RAUDPC), determining the percentage of dead plants (PDP), and measuring the evolution of morphological parameters in inoculated plants over time. In addition, the density levels of V. dahliae in the stem of root-inoculated genotypes have been quantified by means of quantitative real-time PCR at 35 and 120 days after inoculation (dai). Fifteen genotypes (22%) were cataloged as resistant to V. dahliae (i.e., disease parameters did not significantly differ from those of the resistant cultivar Frantoio, or were even lower). Resistant genotypes are characterized by presenting fewer symptoms and a lower amount of V. dahliae DNA at 120 dai than at 35 dai, indicating their ability to control the disease and reduce the density of the pathogen. The rest of the evaluated genotypes showed variable levels of susceptibility. Overall analysis of all genotypes showed high correlation between symptomatology and the amount of V. dahliae DNA in the stem of inoculated genotypes at 120 dai, rather than at 35 dai. However, correlation at 120 dai was not observed in the set of resistant genotypes, suggesting that resistance to defoliating V. dahliae in olive is based on the occurrence of different mechanisms such as avoidance or tolerance. These mechanisms are valuable for designing breeding programs and for the identification of target genes and resistant rootstocks to better control Verticillium wilt in the olive grove.

Alpha-amylase inhibitory activity and antioxidant effect of Olea var. europaea sylvestris leaves extracts.

Evaluation of medicinal plants for their antidiabetic activities has increased considerably around the world as well as in Algeria. Olea europaea var. sylvestris , commonly called Ezzeboudj, is traditionally used by Tlemcen population in Algeria, for treating diabetes mellitus. In this work, we studied the antioxidant activity of wild olive leaves crude extracts, by free radical DPPH scavenging method and iron reduction FRAP. On the other hand, evaluation of the ability of the extracts to inhibit α-amylase activity. The qualitative phytochemical screening carried out on O. europaea var. sylvestris leaves extracts showed the presence of tannins, sterols and triterpenes, saponins, flavonoids and terpenoids. A quantitative analysis of the crude extracts showed significant levels of total polyphenols and flavonoids in hydroacetonic extract, with an amount of 228,45 ± 0,03 mg GAE /g and 204,8 ± 0,04 mg CE /g, respectively. The results obtained from the antioxidant activity showed a high scavenging activity for hydroacetonic extract with an IC 50 of 7,95 ± 0,16 µg/ml. In vitro tests carried out on the inhibitory of α-amylase activity, revealed an inhibitory effects, specifically with hydromethanolic extract in a concetration-dependent manner, with an IC 50 value of 0,91 ± 0,02 mg/ml. These findings reveals that O. europaea var. sylvestris leaves could represent an interesting source of antioxidants and allow to the development of new antidiabetic agents.

Plant response to mycorrhizal inoculation and amendments on a contaminated soil

Understanding the combined effects of soil amendments and inoculation of mycorrhizal fungi on the response of different plant species during the phytostabilization process of trace elements contaminated soils is a challenge. This task is more difficult but more realistic when studied under field conditions. We assess the combined effects of two amendment doses and mycorrhizal inoculation on the response of saplings of two tree species planted in a contaminated field. The amendments were a mix of sugar beet lime and biosolid compost. The inoculation treatments were made with a commercial inoculum of arbuscular mycorrhizal fungi for wild olive and ectomycorrhizal fungi for stone pine. Results showed a weak or null effect of the mycorrhizal inoculation on plant growth, survival and trace element accumulation. There was a significant increase on P nutrition for stone pine, growing on non-amended conditions. Soil amendments were very effective reducing trace elements availability and their accumulation in both plant species, especially in roots. However, the effects on plant biomass were species-dependent and contrasted; low-dose amendments increased the biomass of wild olive by 33.3%, but reduced by 28% that of pine. The high doses of amendments (60 T ha−1) produced some negative effects on plant growth and nutrition, probably related to the increase of soil salinity. Both plant species, stone pine and wild olive, have been proved to be adequate for phytostabilization of contaminated soils under Mediterranean climate, due to their drought tolerance and the low transfer of trace elements from root to shoot, thus reducing toxicity for the food web. To implement microbial-assisted phytoremediation approaches, a better understanding of the diversity and ecology of plant-associated microorganisms is needed. The use of indigenous fungi, locally adapted and tolerant to contamination, would be more suitable for phytostabilization purposes.

Alpha-amylase inhibitory activity and antioxidant effect of Olea var. europaea sylvestris leaves extracts.

Evaluation of medicinal plants for their antidiabetic activities has increased considerably around the world as well as in Algeria. Olea europaea var. sylvestris, commonly called Ezzeboudj, is traditionally used by Tlemcen population in Algeria, for treating diabetes mellitus. In this work, we studied the antioxidant activity of wild olive leaves crude extracts, by free radical DPPH scavenging method and iron reduction FRAP. On the other hand, evaluation of the ability of the extracts to inhibit α-amylase activity. The qualitative phytochemical screening carried out on O. europaea var. sylvestris leaves extracts showed the presence of tannins, sterols and triterpenes, saponins, flavonoids and terpenoids. A quantitative analysis of the crude extracts showed significant levels of total polyphenols and flavonoids in hydroacetonic extract, with an amount of 228,45 ± 0,03 mg GAE /g and 204,8 ± 0,04 mg CE /g, respectively. The results obtained from the antioxidant activity showed a high scavenging activity for hydroacetonic extract with an IC50 of 7,95 ± 0,16 µg/ml. In vitro tests carried out on the inhibitory of α-amylase activity, revealed an inhibitory effects, specifically with hydromethanolic extract in a concetration-dependent manner, with an IC50 value of 0,91 ± 0,02 mg/ml. These findings reveals that O. europaea var. sylvestris leaves could represent an interesting source of antioxidants and allow to the development of new antidiabetic agents.

The use of DNA barcoding to avoid adulteration in olive plant leaf products

Abstract. Partovi R, Iranbakhsh A, Sheidai M, Ebadi M. 2020. The use of DNA barcoding to avoid adulteration in olive plant leaf products. Asian J For 5: 42-47. The leaves of olive plant species Olea europeae, and O. europeae var. cuspidata have been used for medicinal perfused in Iran. The first species leaves have been used to control the blood pressure, while the leaves of wild olive have been used for abortion by locals. Our preliminary inspection of the medicinal plant market revealed that the leaves of these two olive species are sold mistakenly to the consumers and their health might be at risk. Therefore, we permed this investigation to produce DNA barcodes for correct identification of these two olive species and also identify the potential adulteration in our local market. We used Internal transcribed spacer (ITS), as well as plastid genome trnL-F intergenic spacer and ribosomal protein L16 (rpL16) sequences. These sequences after alignment and curation produced DNA barcodes that can differentiate the two olive species from each other. The phylogenetic trees constructed also separated the samples of these olive species and confirmed the potential use of these short DNA sequences for olive barcoding. The present study revealed that some of the local shops mistakenly sell the wild olive leaves instead of the cultivated olive leaf to be used for blood pressure. This mistake endangers the health of pregnant women consumers if they carry a child. We suggest using a combination of nuclear ITS and plastid intergenic spacer (trnL-F and rpL16) regions for DNA barcoding of olive plants to avoid leaf product adulteration.

New Distribution and Molecular Diversity of the Reniform Nematode Rotylenchulus macrosoma (Nematoda: Rotylenchulinae) in Europe.

Reniform nematodes of the genus Rotylenchulus are semi-endoparasites of numerous herbaceous and woody plant species roots and occur largely in regions with temperate, subtropical, and tropical climates. In this study, we provide new records of the nematode Rotylenchulus macrosoma in eight European countries (Czech Republic, France, Germany, Hungary, Italy, Romania, Serbia, and Portugal), in addition to the six Mediterranean countries (Greece, Israel, Jordan, Spain, Syria, and Turkey) where the nematode was previously reported. Four new host species (corn, pea, wheat, and an almond-peach hybrid rootstock) are added to the recorded host species (bean, chickpea, hazelnut, peanut, soybean, and wild and cultivated olive). Molecular analyses based on the cytochrome c oxidase subunit coxI and D2-D3 segments of 28S RNA markers showed high diversity and pronounced genetic structure among populations of Rotylenchulus macrosoma. However, the complexity of phylogeographic patterns in plant-parasitic nematodes may be related to the intrinsic heterogeneity in the distribution of soil organisms, a rare occurrence of a species, or the potential human impact associated with agricultural practices.

Verticillium dahliae Inoculation and in vitro Propagation Modify the Xylem Microbiome and Disease Reaction to Verticillium Wilt in a Wild Olive Genotype

Host resistance is the most practical, long-term, and economically efficient disease control measure for Verticillium wilt in olive caused by the xylem-invading fungus Verticillium dahliae (Vd), and it is at the core of the integrated disease management. Plant’s microbiome at the site of infection may have an influence on the host reaction to pathogens; however, the role of xylem microbial communities in the olive resistance to Vd has been overlooked and remains unexplored to date. This research was focused on elucidating whether in vitro olive propagation may alter the diversity and composition of the xylem-inhabiting microbiome and if those changes may modify the resistance response that a wild olive clone shows to the highly virulent defoliating (D) pathotype of Vd. Results indicated that although there were differences in microbial communities among the different propagation methodologies, most substantial changes occurred when plants were inoculated with Vd, regardless of whether the infection process took place, with a significant increase in the diversity of bacterial communities when the pathogen was present in the soil. Furthermore, it was noticeable that olive plants multiplied under in vitro conditions developed a susceptible reaction to D Vd, characterized by severe wilting symptoms and 100% vascular infection. Moreover, those in vitro propagated plants showed an altered xylem microbiome with a decrease in total OTU numbers as compared to that of plants multiplied under non-aseptic conditions. Overall, 10 keystone bacterial genera were detected in olive xylem regardless of infection by Vd and the propagation procedure of plants (in vitro vs nursery), with Cutibacterium (36.85%), Pseudomonas (20.93%), Anoxybacillus (6.28%), Staphylococcus (4.95%), Methylobacterium-Methylorubrum (3.91%), and Bradyrhizobium (3.54%) being the most abundant. Pseudomonas spp. appeared as the most predominant bacterial group in micropropagated plants and Anoxybacillus appeared as a keystone bacterium in Vd-inoculated plants irrespective of their propagation process. Our results are the first to show a breakdown of resistance to Vd in a wild olive that potentially may be related to a modification of its xylem microbiome and will help to expand our knowledge of the role of indigenous xylem microbiome on host resistance, which can be of use to fight against main vascular diseases of olive.

Processing Effect and Characterization of Olive Oils from Spanish Wild Olive Trees (Olea europaea var. sylvestris).

Wild olive trees have important potential, but, to date, the oil from wild olives has not been studied significantly, especially from an analytical point of view. In Spain, the wild olive tree is called “Acebuche” and its fruit “Acebuchina”. The objective of this work is to optimize the olive oil production process from the Acebuchina cultivar and characterize the oil, which could be marketed as healthy and functional food. A Box–Behnken experimental design with five central points was used, along with the Response Surface Methodology to obtain a mathematical experimental model. The oils from the Acebuchina cultivar meet the requirements for human consumption and have a good balance of fatty acids. In addition, the oils are rich in antioxidants and volatile compounds. The highest extraction yield, 12.0 g oil/100 g paste, was obtained at 90.0 min and the highest yield of phenolic compounds, 870.0 mg/kg, was achieved at 40.0 °C, and 90.0 min; but the maximum content of volatile compounds, 26.9 mg/kg, was obtained at 20 °C and 30.0 min. The oil yield is lower than that of commercial cultivars, but the contents of volatile and phenolic compounds is higher.

Wild Olive Trees Extent in Al-Baha Region, Saudi Arabia According to Trees’ Age, Health, and Clustering Status

This study provided detailed information on the attributes of wild olive species in the Al- Baha region, Saudi Arabia. The study area lay along the Sarah mountain, encompassing the districts of Al-Qura, Al-Mandaq, Al- Baha and the southern part of Baljurashi. This indicates the preference of wild olive for high foggy mountain conditions, which was pre-determined by the study to be a medium-high vegetation density zone. Information extracted from high resolution satellite imagery Pleaides revealed that there are 717,894 wild olive trees (360 trees per km2) in the study area, covering 1,991 km2 .The districts of Al-Mandaq and Al-Baha have higher wild olive density with younger and highly clustered trees, whereas Al-Qura and Baljurashi districts have lower wild olive density, with medium clustered older trees. The districts of Al-Aqiq, Qelwa and Mekhwa have the least density of wild olive with younger trees and light clustering. Clustering behavior was enumerated directly at the sampling plots and the results depicted that the majority of wild olives occur in clusters with mostly 5-10 trees per cluster. The olive tree is found naturally in Al-Baha and can reportedly maintain its populations in natural old growth forests for several hundred years. This study identified the age of wild olive trees in the study area. The results indicated that there were more (68%) of young age class (<50 years old) of wild olive trees, whereas Baljurashi showed the highest percentage of old age class (>150 years). The majority (88.6%) of the wild olive trees were healthy, while more unhealthy trees were observed in Al-Mandaq and Al-Baha districts. As observed during the groundwork, unhealthy trees particularly due to dieback, were more discerned with juniper affecting vegetation in Al-Mandaq and South Baha, with 45% and 18% respectively. Similarly, this study recorded trace of unhealthy vegetation, with 11.4% of the wild olive trees in an unhealthy condition. This information would be essential in ‘Identifying the Landscape Preference of Wild Olive in Al-Baha Region Saudi Arabia’.

Intensive olive production at Levantine sites. New data from Fadous-Kfarabida and Khirbet-ez Zeraqon

During the third millennium BCE, the Levant experienced an increase in social complexity, visible in the emergence of urban forms and centralised institutions. Specialised agricultural production, particularly of olives, has long been considered a key factor in this transformation. This paper uses charcoal and seed analysis of remains from the Early Bronze Age II-III sites of Tell Fadous-Kfarabida in Lebanon and Khirbet-ez Zeraqon in Jordan, alongside a comparative analysis of published data, to investigate this phenomenon. Olive was an important crop at both sites but Khirbet-ez Zeraqon is situated within a more arid inland location, away from the natural distribution of wild olive, whereas Tell Fadous-Kfarabida had a much lusher vegetation, and was within the distribution of wild olive. While important, olive was possibly not the major crop in terms of macro-nutrient supply in Khirbet-ez Zeraqon but it played a more dominant role in Fadous-Kfarabida. The measurements of the olive stones from both sites show a high variance compared to other sites. At Khirbet-ez Zeraqon this may have been due to specialization by using several cultivars and/or applying irrigation and/or fluctuations in rainfall. At Fadous-Kfarabida morphological wild olives were possibly included in the production as well, which may relate to the development of new olive strains and a likely higher engagement in experimentation. Although an overall linear trend of increasing mean olive stone length, occasionally described as “domestication syndrome”, can be detected for the southern Levant between 7 and 2 kyr BP, the Early Bronze Age measurement data from Fadous-Kfarabida and Khirbet-ez Zeraqon are outside the confidence band of the regression line and indicate that higher variability in some sites can blur a straightforward recognition of the “domestication syndrome”. There seem to have been varied local practices in cultivation and domestication in the Early Bronze Age Levant.

Reusable Na-SiO2@CeO2catalyst for efficient biodiesel production from non-edible wild olive oil as a new and potential feedstock

The main purpose of the current research work is to design competent heterogeneous catalyst for the development of sustainable biodiesel technology. Therefore, a novel and an efficient Na-SiO2@CeO2 heterogeneous catalyst was designed for sustainable and eco-friendly biodiesel production using wild olive oil as a new and potentially non-edible feedstock. The designed catalyst was further characterized by using FT-IR, BET-BJH, SEM, EDX, XPS and XRD spectroscopic techniques. The experimental results demonstrated that the synthesized catalyst appeared to be efficient for the conversion of wild olive oil to biodiesel, providing maximum yield of 97% at optimum reaction conditions: catalyst concentration 2.5w/w%, reaction duration 120 min, reaction temperature 65 °C, and oil/methanol molar ratio 1:10. It was observed from the endurance test that the synthesized catalyst has remarkable catalytic potency upto five consecutive runs, showing profound stability with negligible leaching of the active basic sites from the surface of the catalyst.

Erratum to “Roberto Corona, Nicola Montaldo: On the transpiration of wild olives under water-limited conditions in a heterogenous ecosystem with shallow soil over fractured rock. DOI: 10.2478/johh-2020-0022“

Sciendo provides publishing services and solutions to academic and professional organizations and individual authors. We publish journals, books, conference proceedings and a variety of other publications.

Early production of table olives at a mid-7th millennium BP submerged site off the Carmel coast (Israel)

We present here the earliest evidence for large-scale table olive production from the mid-7th millennium BP inundated site of Hishuley Carmel on the northern Mediterranean coast of Israel. Olive pit size and fragmentation patterns, pollen as well as the architecture of installations associated with pits from this site, were compared to finds from the nearby and slightly earlier submerged Kfar Samir site. Results indicate that at Kfar Samir olive oil was extracted, while at Hishuley Carmel the data showed that large quantities of table olives, the oldest reported to date, were prepared. This process was most probably facilitated by the site’s proximity to the Mediterranean Sea, which served as a source of both sea water and salt required for debittering/pickling/salting the fruit, as experimentally demonstrated in this study. Comparison of pit morphometry from modern cultivars, wild-growing trees and the archaeological sites, intimates that in pit morphology the ancient pits resemble wild olives, but we cannot totally exclude the possibility that they derive from early cultivated trees. Our findings demonstrate that in this region, olive oil production may have predated table olive preparation, with each development serving as a milestone in the early exploitation of the olive.

Identifying the Topographic Slope Characteristics Most Preferred By Wild Olive Trees in Al-Bahah Region, Saudi Arabia

The aims of this research were to identify the topographical slope characteristics most preferred by wild olive trees in the Al-Bahah region. This study successfully identified the degree of the slope preferred for wild olive groves. The findings revealed that the majority (72.9%) of wild olive trees in Al-Bahah region occupy slopes of 5–30°. However, the patterns in Qelwa and Al-Mekhwah districts are a bit different where most of the wild olives were found on steeper slopes of 20–40°. This is probably because these sub-regions have a medium to steep slope, descending gradually toward the west, the altitudes ranging from 200 (400) to 2001 and 2200 m west of Al¬-Bahah city and Uwera, and between 2000 and 2100 m west of Baljurashi. The results further depicted that the wild olive with the medium-large crown diameter mostly occupied the gentler slopes of 0–25° compared to those with small crown diameters at steeper slopes of 5–35°. This indicates that the wild olive trees grow better on gentler slopes. These findings can be regarded as theoretically revealing the potential landform suitable for olive plantation. As a basis for olive plantation site suitability, these factors are the essential prerequisites to be considered. However. In addition, it is obvious that site suitability is subject to the temporal dynamics of environmental variables.

Landscape and fuel management in the context of prehistoric and historical occupations of Cova des Moro (Manacor, Mallorca, Spain)

In this paper, the first results of charcoal analyses carried out at Cova des Moro (Manacor, Mallorca, Spain) are presented. This cave is an archaeological but also palaeontological site that provides information on endemic fauna (the extinct caprine Myotragus balearicus) before the arrival of humans and, later, the relationship between the first farmers and the landscape. Several human occupations in the cave have been documented, from the Chalcolithic (end of the 3rd millennium cal BC), the Bronze Age (2nd millennium cal BC) and, finally, the Almohad period (13th century AD), during which the cave was used for different purposes.The first results of charcoal analyses at Cova des Moro provide information about the natural plant communities exploited by humans for comparison with later sequences, enabling us to evaluate how humans managed this territory over time. The results point to the exploitation of Mediterranean woodlands with wild olive (Olea europaea), mastic (Pistacia lentiscus), green olive tree (Phillyrea), Aleppo pine (Pinus halepensis), rosemary (Rosmarinus officinalis), juniper (Juniperus) and rockrose species (Cistus), among others; these taxa would become the main elements of Mallorca's coastal landscape in later times, and it has been proven that they would already have been present as the island's natural flora at the time humans arrived there.

HERCULES AND THE STONE TREE: AENEID 8.233–40

In ancient literature and religion, Hercules—in common with many other deities—is frequently associated with particular trees or types of tree. There are tales connecting him with the wild olive, laurel and oak, but his most prominent and frequent arboreal link is with the poplar (populus Alcidae gratissima, ‘the poplar is most delightful to Hercules’, Verg. Ecl. 7.61), an association mentioned twice in the Hercules-heavy first half of Aeneid Book 8 (276, 286). The festival of Hercules celebrated by Evander and his people takes place just outside the city within a ‘great grove’ (Aen. 8.103–4) of unspecified species, in an area surrounded by less defined expanses of trees. Trees crowd the banks of the Tiber, leaning out for wonder as Aeneas’ fleet passes by (Aen. 8.91–2) and soon uariisque teguntur | arboribus, uiridisque secant placido aequore siluas (‘[the Trojans] are covered by different trees and cut their way through green woods on the calm water’, Aen. 8.95–6); looking up through the sacrificial smoke on the altars, Pallas and his friends are initially frightened ut celsas uidere rates atque inter opacum | adlabi nemus (‘as they saw the tall ships glide towards them through the dark grove’, Aen. 8.107–8). When Evander later shows Aeneas around, the emphasis on trees recurs, with the huge grove destined to become Romulus’ Asylum (Aen. 8.342), and the bramble- and god-haunted woods of the Capitol (Aen. 8.347–54). Later, Aeneas and his men camp in a vast grove of Silvanus, as Venus approaches to bring her son his new shield (Aen. 8.597–607).

Soil fungal diversity and functionality are driven by plant species used in phytoremediation

Soil biodiversity loss due to pollution may affect ecosystem services negatively. This environmental problem may be solved by phytoremediation, which is an effective strategy to manage and remediate contaminated areas. During this remediation process, the establishment of plant communities may improve soil fungal community structure and, in particular, may favour mycorrhizal symbiotic associations. As a consequence, afforestation of degraded lands will have different outcomes on fungal diversity and functionality, which will depend on the selected tree and shrub species.We analysed soil fungal diversity and functional guilds by high-throughput sequencing of environmental DNA in a trace element contaminated area, part of a large scale phytoremediation project running for 20 years. We selected five habitats for comparison purposes: three under the canopy of selected tree species (wild olive, white poplar and stone pine), adjacent treeless areas (grassland) and non-remediated areas (bare soil).Soil fungal diversity and richness seemed to be enhanced by phytoremediation. White poplar soil had the highest diversity and richness compared to wild olive and stone pine. Fungal communities were especially different between stone pine, with soils rich in organic C and high C:N ratio, and grassland soils.We identified 9,428 fungal OTUs from which 1,283 were assigned to a unique functional guild; the most abundant belonging to saprotrophic, plant pathogenic and ectomycorrhizal functional guilds. Ectomycorrhizal fungi were more abundant in soils under ectomycorrhizal host trees. Saprotrophs were abundant in grassland and wild olive soils, while plant pathogens were abundant in non-remediated soils.The remediation of soils (clean-up and amendment addition) allowed the natural establishment of grassland habitats throughout the study area, increasing fungal diversity, richness, taxonomy and functionality, when compared to non-remediated soils. Tree afforestation allowed the establishment of a forest type community bringing a further recruitment of fungal taxa, mainly the ectomycorrhizal fungal guild. Afforestation with different tree species showed species-specific effects on soil N, organic C, Ca and C:N ratio which led to increased spatial heterogeneity in areas with potential to recruit a wider diversity of fungi.