Annotation of biologically relevant ligands in UniProtKB using ChEBI.

MOTIVATION: To provide high quality, computationally tractable annotation of binding sites for biologically relevant (cognate) ligands in UniProtKB using the chemical ontology ChEBI (Chemical Entities of Biological Interest), to better support efforts to study and predict functionally relevant interactions between protein sequences and structures and small molecule ligands. RESULTS: We structured the data model for cognate ligand binding site annotations in UniProtKB and performed a complete reannotation of all cognate ligand binding sites using stable unique identifiers from ChEBI, which we now use as the reference vocabulary for all such annotations. We developed improved search and query facilities for cognate ligands in the UniProt website, REST API and SPARQL endpoint that leverage the chemical structure data, nomenclature and classification that ChEBI provides. AVAILABILITY AND IMPLEMENTATION: Binding site annotations for cognate ligands described using ChEBI are available for UniProtKB protein sequence records in several formats (text, XML and RDF) and are freely available to query and download through the UniProt website (www.uniprot.org), REST API (www.uniprot.org/help/api), SPARQL endpoint (sparql.uniprot.org/) and FTP site (https://ftp.uniprot.org/pub/databases/uniprot/). SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Exploring the Influence of Date Palm Cultivars on Soil Microbiota.

Plants thrive in diverse environments, where root-microbe interactions play a pivotal role. Date palm (Phoenix dactylifera L.), with its genetic diversity and resilience, is an ideal model for studying microbial adaptation to different genotypes and stresses. This study aimed to analyze the bacterial and fungal communities associated with traditional date palm cultivars and the widely cultivated "Deglet Nour" were explored using metabarcoding approaches. The microbial diversity analysis identified a rich community with 13,189 bacterial and 6442 fungal Amplicon Sequence Variants (ASVs). Actinobacteriota, Proteobacteria, and Bacteroidota dominated bacterial communities, while Ascomycota dominated fungal communities. Analysis of the microbial community revealed the emergence of two distinct clusters correlating with specific date palm cultivars, but fungal communities showed higher sensitivity to date palm genotype variations compared to bacterial communities. The commercial cultivar "Deglet Nour" exhibited a unique microbial composition enriched in pathogenic fungal taxa, which was correlated with its genetic distance. Overall, our study contributes to understanding the complex interactions between date palm genotypes and soil microbiota, highlighting the genotype role in microbial community structure, particularly among fungi. These findings suggest correlations between date palm genotype, stress tolerance, and microbial assembly, with implications for plant health and resilience. Further research is needed to elucidate genotype-specific microbial interactions and their role in enhancing plant resilience to environmental stresses.

Rhea, the reaction knowledgebase in 2022.

Rhea (https://www.rhea-db.org) is an expert-curated knowledgebase of biochemical reactions based on the chemical ontology ChEBI (Chemical Entities of Biological Interest) (https://www.ebi.ac.uk/chebi). In this paper, we describe a number of key developments in Rhea since our last report in the database issue of Nucleic Acids Research in 2019. These include improved reaction coverage in Rhea, the adoption of Rhea as the reference vocabulary for enzyme annotation in the UniProt knowledgebase UniProtKB (https://www.uniprot.org), the development of a new Rhea website, and the designation of Rhea as an ELIXIR Core Data Resource. We hope that these and other developments will enhance the utility of Rhea as a reference resource to study and engineer enzymes and the metabolic systems in which they function.

Bioprospection of the bacterial ß-myrcene-biotransforming trait in the rhizosphere.

The biocatalysis of ß-myrcene into value-added compounds, with enhanced organoleptic/therapeutic properties, may be performed by resorting to specialized enzymatic machinery of ß-myrcene-biotransforming bacteria. Few ß-myrcene-biotransforming bacteria have been studied, limiting the diversity of genetic modules/catabolic pathways available for biotechnological research. In our model Pseudomonas sp. strain M1, the ß-myrcene catabolic core-code was identified in a 28-kb genomic island (GI). The lack of close homologs of this ß-myrcene-associated genetic code prompted a bioprospection of cork oak and eucalyptus rhizospheres, from 4 geographic locations in Portugal, to evaluate the environmental diversity and dissemination of the ß-myrcene-biotransforming genetic trait (Myr+). Soil microbiomes were enriched in ß-myrcene-supplemented cultures, from which ß-myrcene-biotransforming bacteria were isolated, belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Sphingobacteriia classes. From a panel of representative Myr+ isolates that included 7 bacterial genera, the production of ß-myrcene derivatives previously reported in strain M1 was detected in Pseudomonas spp., Cupriavidus sp., Sphingobacterium sp., and Variovorax sp. A comparative genomics analysis against the genome of strain M1 found the M1-GI code in 11 new Pseudomonas genomes. Full nucleotide conservation of the ß-myrcene core-code was observed throughout a 76-kb locus in strain M1 and all 11 Pseudomonas spp., resembling the structure of an integrative and conjugative element (ICE), despite being isolated from different niches. Furthermore, the characterization of isolates not harboring the Myr+-related 76-kb locus suggested that they may biotransform ß-myrcene via alternative catabolic loci, being thereby a novel source of enzymes and biomolecule catalogue for biotechnological exploitation. KEY POINTS: • The isolation of 150 Myr+ bacteria hints the ubiquity of such trait in the rhizosphere. • The Myr+ trait is spread across different bacterial taxonomic classes. • The core-code for the Myr+ trait was detected in a novel ICE, only found in Pseudomonas spp.

A Sustainable Approach for the Valorization of Underutilized Date Fruits.

Secondary varieties of date fruits are often discarded because they do not have commercial value. However, their phytochemicals are very similar to those of the primary ones and therefore, they can be valorized as a source of compounds of interest, mainly phenols and dietary fiber. Their chemical composition changes with ripening, so their characterization throughout this process is of great significance. Date fruit samples were harvested at Khalal, Rutab, and Tamer stages, and a mixture of fruits from ornamental date trees was also analyzed. Aqueous and ethanolic extracts were studied for their phenolic composition. In aqueous extracts, phenols decreased with ripening, while in the ethanolic ones having higher phenolic content. Chelidonic acid, a γ-pyrone, was the major compound found in all extracts, but in the ethanolic ones, flavonoids were also present in similar amounts. After purification by adsorption chromatography, all extracts were assayed for their antimicrobial activity. Those from the Tamer stage showed the highest activity, especially against Gram-positive bacteria. The fibrous residues after aqueous and ethanolic extractions were also characterized. Their chemical composition suggested that they can be considered as a good source of prebiotic arabinoxylans and antioxidant fiber, whose antiradical activity correlated with their phenolic content. Date fruits from secondary varieties are promising as a worthwhile starting point for obtaining new value-added products.

The influence of bioclimate on soil microbial communities of cork oak.

BACKGROUND: Soil microbiomes are important to maintain soil processes in forests and confer protection to plants against abiotic and biotic stresses. These microbiomes can be affected by environmental changes. In this work, soil microbial communities from different cork oak Portuguese forests under different edaphoclimatic conditions were described by using a metabarcoding strategy targeting ITS2 and 16S barcodes. RESULTS: A total of 11,974 fungal and 12,010 bacterial amplicon sequence variants (ASVs) were obtained, revealing rich and diverse microbial communities associated with different cork oak forests. Bioclimate was described as the major factor influencing variability in these communities (or bioclimates/cork oak forest for fungal community), followed by boron and granulometry. Also, pH explained variation of fungal communities, while C:N ratio contributed to bacterial variation. Fungal and bacterial biomarker genera for specific bioclimates were described. Their co-occurrence network revealed the existence of a complex and delicate balance among microbial communities. CONCLUSIONS: The findings revealed that bacterial communities are more likely to be affected by different edaphoclimatic conditions than fungal communities, also predicting a higher impact of climate change on bacterial communities. The integration of cork oak fungal and bacterial microbiota under different bioclimates could be further explored to provide information about useful interactions for increasing cork oak forest sustainability in a world subject to climate changes.

Going virtual and going wide: comparing Team-Based Learning in-class versus online and across disciplines.

Team-based learning (TBL) is an active learning pedagogy developed for in-class sessions and based on the collaborative work of small groups of students. The increasing push to online and blended learning has enhanced the need to expand this pedagogy to a virtual environment, but little evidence has been produced on how students accept online synchronous sessions of TBL. The purpose of this study, that relies on 427 responses, is to present a comparative perspective of traditional in-class versus adapted fully synchronous online TBL and across different disciplinary fields. Students of two different academic years and different programs were surveyed for their acceptance of TBL. They were invited to answer closed-ended questions focused on their engagement in all TBL learning process and the final outcomes provided. Results obtained from this unique comparative study revealed a wide approval of TBL, regardless of the environment (online or in-class TBL sessions), scientific area of courses and student gender. The acceptance of fully online TBL sessions, in a similar way as traditional in-class sessions, could be a rationale for giving more use to the 'virtual' context. Other results corroborated previous researches on TBL, such the need of student awareness of TBL benefits to get more engaged in the process or the impact of student activities overload on the TBL process. Implications are informative for pedagogical practice.

Enzyme annotation in UniProtKB using Rhea.

MOTIVATION: To provide high quality computationally tractable enzyme annotation in UniProtKB using Rhea, a comprehensive expert-curated knowledgebase of biochemical reactions which describes reaction participants using the ChEBI (Chemical Entities of Biological Interest) ontology. RESULTS: We replaced existing textual descriptions of biochemical reactions in UniProtKB with their equivalents from Rhea, which is now the standard for annotation of enzymatic reactions in UniProtKB. We developed improved search and query facilities for the UniProt website, REST API and SPARQL endpoint that leverage the chemical structure data, nomenclature and classification that Rhea and ChEBI provide. AVAILABILITY AND IMPLEMENTATION: UniProtKB at https://www.uniprot.org; UniProt REST API at https://www.uniprot.org/help/api; UniProt SPARQL endpoint at https://sparql.uniprot.org/; Rhea at https://www.rhea-db.org.

Bacteria could help ectomycorrhizae establishment under climate variations.

Rhizosphere microbiome is one of the main sources of plant protection against drought. Beneficial symbiotic microorganisms, such as ectomycorrhizal fungi (ECMF) and mycorrhiza helper bacteria (MHB), interact with each other for increasing or maintaining host plant fitness. This mutual support benefits all three partners and comprises a natural system for drought acclimation in plants. Cork oak (Quercus suber L.) tolerance to drought scenarios is widely known, but adaptation to climate changes has been a challenge for forest sustainability protection. In this work, ECMF and MHB communities from cork oak forests were cross-linked and correlated with climates. Cenococcum, Russula and Tuber were the most abundant ECMF capable of interacting with MHB (ECMF~MHB) genera in cork oak stands, while Bacillus, Burkholderia and Streptomyces were the most conspicuous MHB. Integrating all microbial data, two consortia Lactarius/Bacillaceae and Russula/Burkholderaceae have singled out but revealed a negative interaction with each other. Russula/Burkholderaceae might have an important role for cork oak forest sustainability in arid environments, which will be complemented by the lower drought adaptation of competitive Lactarius/Bacillaceae. These microbial consortia could play an essential role on cork oak forest resilience to upcoming climatic changes.

Epiphytic and Endophytic Bacteria on Olive Tree Phyllosphere: Exploring Tissue and Cultivar Effect.

Variation on bacterial communities living in the phyllosphere as epiphytes and endophytes has been attributed to plant host effects. However, there is contradictory or inconclusive evidence regarding the effect of plant genetics (below the species' level) and of plant tissue type on phyllosphere bacterial community assembly, in particular when epiphytes and endophytes are considered simultaneously. Here, both surface and internal bacterial communities of two olive (Olea europaea) cultivars were evaluated in twigs and leaves by molecular identification of cultivable isolates, with an attempt to answer these questions. Overall, Proteobacteria, Actinobacteria and Firmicutes were the dominant phyla, being epiphytes more diverse and abundant than endophytes. Host genotype (at cultivar level) had a structuring effect on the composition of bacterial communities and, in a similar way, for both epiphytes and endophytes. Plant organ (leaf vs. twig) control of the bacterial communities was less evident when compared with plant genotype and with a greater influence on epiphytic than on endophytic community structure. Each olive genotype/plant organ was apparently selective towards specific bacterial operational taxonomic units (OTUs), which may lead to specific feedbacks on fitness of plant genotypes. Bacterial recruitment was observed to happen mainly within epiphytes than in endophytes and in leaves as compared with twigs. Such host specificity suggested that the benefits derived from the plant-bacteria interaction should be considered at genetic levels below the species.

Endophytic and Epiphytic Phyllosphere Fungal Communities Are Shaped by Different Environmental Factors in a Mediterranean Ecosystem.

The diversity and factors influencing fungal assemblages in phyllosphere of Mediterranean tree species have been barely studied, especially when endophytic and epiphytic communities are simultaneously considered. In this work, the endophytic and epiphytic fungal communities from olive tree phyllosphere were studied. This tree species is natural from the Mediterranean region and adapted to grow under adverse climatic conditions. The main objectives were to determine whether there are differences between both fungal communities and to examine whether different abiotic (climate-related) and biotic (plant organs) factors play a pivotal role in structuring these communities. Both communities differed in size and composition, with epiphytic community being richer and more abundant, displaying also a dominance of melanized fungi. Season was the major driver of community composition, especially of epiphytes. Other drivers shaping epiphytes were wind speed and temperature, while plant organ, rainfall, and temperature were the major drivers for endophytic composition. In contrast, canopy orientation caused slight variations in community composition of fungi, but with distinct effects in spring and autumn seasons. In conclusion, epiphytic and endophytic communities are not driven by the same factors. Several sources of variation undergo complex interactions to form and maintain phyllosphere fungal community in Mediterranean climates. Climatic parameters have influence on these fungal communities, suggesting that they are likely to be affected by climate changes in a near future.

Ectomycorrhizal fungal diversity and community structure associated with cork oak in different landscapes.

Cork oak (Quercus suber L.) forests play an important ecological and economic role. Ectomycorrhizal fungi (ECMF) are key components for the sustainability and functioning of these ecosystems. The community structure and composition of ECMF associated with Q. suber in different landscapes of distinct Mediterranean bioclimate regions have not previously been compared. In this work, soil samples from cork oak forests residing in different bioclimates (arid, semi-arid, sub-humid, and humid) were collected and surveyed for ectomycorrhizal (ECM) root tips. A global analysis performed on 3565 ECM root tips revealed that the ECMF community is highly enriched in Russula, Tomentella, and Cenoccocum, which correspond to the ECMF genera that mainly contribute to community differences. The ECMF communities from the rainiest and the driest cork oak forests were distinct, with soils from the rainiest climates being more heterogeneous than those from the driest climates. The analyses of several abiotic factors on the ECMF communities revealed that bioclimate, precipitation, soil texture, and forest management strongly influenced ECMF structure. Shifts in ECMF with different hyphal exploration types were also detected among forests, with precipitation, forest system, and soil texture being the main drivers controlling their composition. Understanding the effects of environmental factors on the structuring of ECM communities could be the first step for promoting the sustainability of this threatened ecosystem.

Genetic diversity and structure of Iberian Peninsula cowpeas compared to world-wide cowpea accessions using high density SNP markers.

BACKGROUND: Cowpea (Vigna unguiculata L. Walp) is an important legume crop due to its high protein content, adaptation to heat and drought and capacity to fix nitrogen. Europe has a deficit of cowpea production. Knowledge of genetic diversity among cowpea landraces is important for the preservation of local varieties and is the basis to obtain improved varieties. The aims of this study were to explore diversity and the genetic structure of a set of Iberian Peninsula cowpea accessions in comparison to a worldwide collection and to infer possible dispersion routes of cultivated cowpea. RESULTS: The Illumina Cowpea iSelect Consortium Array containing 51,128 SNPs was used to genotype 96 cowpea accessions including 43 landraces and cultivars from the Iberian Peninsula, and 53 landraces collected worldwide. Four subpopulations were identified. Most Iberian Peninsula accessions clustered together with those from other southern European and northern African countries. Only one accession belonged to another subpopulation, while two accessions were 'admixed'. A lower genetic diversity level was found in the Iberian Peninsula accessions compared to worldwide cowpeas. CONCLUSIONS: The genetic analyses performed in this study brought some insights into worldwide genetic diversity and structure and possible dispersion routes of cultivated cowpea. Also, it provided an in-depth analysis of genetic diversity in Iberian Peninsula cowpeas that will help guide crossing strategies in breeding programs.

Cowpea: a legume crop for a challenging environment.

Cowpea is a grain legume native from Africa and is a primary source of protein for millions of people in sub-Saharan Africa and other parts of the developing world. The main important characteristics of this crop include a good protein quality with a high nutritional value, its nitrogen-fixing ability, and an ability to be more drought- and heat-tolerant than most of its legume relatives. In a research perspective, studies of cowpea are relatively scarce, despite its relevance to agriculture in the developing world and its resilience to stress. The present review provides an overview of different aspects of cowpea, with a special emphasis on the molecular markers for assessing genetic diversity, as well as on biochemical and transcriptomic data with respect to evaluating cowpea drought stress tolerance. The integration of both datasets will be useful for the improvement of cowpea because research on drought stress tolerance is of major interest for this crop in a challenging environment. © 2017 Society of Chemical Industry.

European cowpea landraces for a more sustainable agriculture system and novel foods.

BACKGROUND: Genetic diversity is fundamental to breeding programs and consequently has an important role in obtaining new varieties. To properly use the genetic diversity present in germplasm collections, a good knowledge of the agro-morphological traits of each accession is needed. The aim of this study was to explore the production capacity of 24 cowpea landraces from southern Europe, through phenotypic characterization and evaluation in three different locations in Greece and Portugal. RESULTS: Most qualitative parameters tested showed a high stability among the three locations. A wide difference was observed among the three locations with respect to number of days to flowering, ranging from 55 to 99 days. Quantitative traits showed a higher genotype × environment than genetic variance component. In general, an inverse relationship between σ2ge /σ2g ratio (where σ2ge is genotype × genotype interaction and σ2g is genotype impact) and heritability value was observed. Principal component analysis was able to group accessions based on their origin. The first two principal components explained 97.52% of variation, being the number of seeds per plant, plant height and seed protein content, the traits which contributed most to variability. CONCLUSION: The results show that sufficient variation exists in different traits within landraces in the studied cowpea germplasm to pursue a breeding program. However, the quantitative traits showed a higher genotype × environment component. © 2017 Society of Chemical Industry.

A comprehensive assessment of the transcriptome of cork oak (Quercus suber) through EST sequencing.

BACKGROUND: Cork oak (Quercus suber) is one of the rare trees with the ability to produce cork, a material widely used to make wine bottle stoppers, flooring and insulation materials, among many other uses. The molecular mechanisms of cork formation are still poorly understood, in great part due to the difficulty in studying a species with a long life-cycle and for which there is scarce molecular/genomic information. Cork oak forests are of great ecological importance and represent a major economic and social resource in Southern Europe and Northern Africa. However, global warming is threatening the cork oak forests by imposing thermal, hydric and many types of novel biotic stresses. Despite the economic and social value of the Q. suber species, few genomic resources have been developed, useful for biotechnological applications and improved forest management. RESULTS: We generated in excess of 7 million sequence reads, by pyrosequencing 21 normalized cDNA libraries derived from multiple Q. suber tissues and organs, developmental stages and physiological conditions. We deployed a stringent sequence processing and assembly pipeline that resulted in the identification of ~159,000 unigenes. These were annotated according to their similarity to known plant genes, to known Interpro domains, GO classes and E.C. numbers. The phylogenetic extent of this ESTs set was investigated, and we found that cork oak revealed a significant new gene space that is not covered by other model species or EST sequencing projects. The raw data, as well as the full annotated assembly, are now available to the community in a dedicated web portal at http://www.corkoakdb.org. CONCLUSIONS: This genomic resource represents the first trancriptome study in a cork producing species. It can be explored to develop new tools and approaches to understand stress responses and developmental processes in forest trees, as well as the molecular cascades underlying cork differentiation and disease response.

The Impact of the COVID-19 Pandemic on Mental Health and Cognitive Function in Patients With Cancer: A Systematic Literature Review.

BACKGROUND: The COVID-19 pandeminc has had widespread impacts, but its specific effects on mental health and cognitive function in patients with cancer remain under-explored. RECENT FINDINGS: Data from the general population has suggested that mental health problems were frequent during the pandemic, namely during the initial stage of the outbreak. For patients with cancer, a systematic review and meta-analysis of data published until January 2021 also showed elevated prevalence of depression and anxiety, and suggested that anxiety was more frequent than in health workers and healthy controls. OBJECTIVE: This systematic review aimed to synthesize existing evidence on the impact of the COVID-19 pandemic on mental health and cognitive function in patients with cancer. METHODS: Studies were identified through systematic search of three electronic bibliographic databases (PubMed, Web of Science, and EBSCOHOST) with adapted search strings. We included only peer-reviewed, nonqualitative, original research papers, published between 2019 and 2022, and reporting on mental health and/or cognition outcomes during the COVID-19 pandemic in adult patients with cancer. RESULTS: Of 3260 papers identified, 121 full text articles were retrieved and 71 met inclusion criteria. We found that patients with cancer reported high levels of psychological distress, anxiety and depression, as well as cognitive complaints during the pandemic. However, studies were not consistent in identifying these symptoms as effects of the pandemic specific for this population. In fact, longitudinal studies did not find consistent differences between pre- and post-pandemic periods and, globally, patients with cancer did not report increased severity of these mental health symptoms in relation to the general population. CONCLUSION: Overall, while the COVID-19 pandemic may have raised mental health challenges for patients with cancer, the diagnosis of cancer and associated treatments seemed to remain the main source of concern for these patients.

Diversity, Composition, and Specificity of the Philaenus spumarius Bacteriome.

Philaenus spumarius (Linnaeus, 1758) (Hemiptera, Aphrophoridae) was recently classified as a pest due to its ability to act as a vector of the phytopathogen Xylella fastidiosa. This insect has been reported to harbour several symbiotic bacteria that play essential roles in P. spumarius health and fitness. However, the factors driving bacterial assemblages remain largely unexplored. Here, the bacteriome associated with different organs (head, abdomen, and genitalia) of males and females of P. spumarius was characterized using culturally dependent and independent methods and compared in terms of diversity and composition. The bacteriome of P. spumarius is enriched in Proteobacteria, Bacteroidota, and Actinobacteria phyla, as well as in Candidatus Sulcia and Cutibacterium genera. The most frequent isolates were Curtobacterium, Pseudomonas, and Rhizobiaceae sp.1. Males display a more diverse bacterial community than females, but no differences in diversity were found in distinct organs. However, the organ shapes the bacteriome structure more than sex, with the Microbacteriaceae family revealing a high level of organ specificity and the Blattabacteriaceae family showing a high level of sex specificity. Several symbiotic bacterial genera were identified in P. spumarius for the first time, including Rhodococcus, Citrobacter, Halomonas, Streptomyces, and Providencia. Differences in the bacterial composition within P. spumarius organs and sexes suggest an adaptation of bacteria to particular insect tissues, potentially shaped by their significance in the life and overall fitness of P. spumarius. Although more research on the bacteria of P. spumarius interactions is needed, such knowledge could help to develop specific bacterial-based insect management strategies.

Enhancing tomato plants' tolerance to combined heat and salt stress - The role of arbuscular mycorrhizae and biochar.

The Mediterranean basin is highly susceptible to climate change, with soil salinization and the increase in average temperatures being two of the main factors affecting crop productivity in this region. Following our previous studies on describing the detrimental effects of heat and salt stress co-exposure on tomato plants, this study aimed to understand if substrate supplementation with a combination of arbuscular mycorrhizal fungi (AMF) and biochar could mitigate the negative consequences of these stresses. Upon 21 days of exposure, stressed tomato plants grown under supplemented substrates showed increased tolerance to heat (42 °C for 4 h/day), salt (100 mM NaCl), and their combination, presenting increased biomass and flowering rate. The beneficial effects of AMF and biochar were associated with a better ionic balance (i.e. lower sodium accumulation and higher uptake of calcium and magnesium) and increased photosynthetic efficiency. Indeed, these plants presented higher chlorophyll content and improved CO2 assimilation rates. Biochemical data further supported that tomato plants grown with AMF and biochar were capable of efficiently modulating their defence pathways, evidenced by the accumulation of proline, ascorbate, and glutathione, coupled with a lower dependency on energy-costly enzymatic antioxidant players. In summary, the obtained data strongly point towards a beneficial role of combined AMF and biochar as sustainable tools to improve plant growth and development under a climate change scenario, where soil salinization and heat peaks often occur together.

Deciphering plant health status: The link between secondary metabolites, fungal community and disease incidence in olive tree.

Plant-associated microorganisms are increasingly recognized to play key roles in host health. Among several strategies, associated microorganisms can promote the production of specific metabolites by their hosts. However, there is still a huge gap in the understanding of such mechanisms in plant-microorganism interaction. Here, we want to determine whether different levels of olive leaf spot (OLS) disease incidence were related to differences in the composition of fungal and secondary metabolites (i.e. phenolic and volatile compounds) in leaves from olive tree cultivars with contrasting OLS susceptibilities (ranging from tolerant to highly susceptible). Accordingly, leaves with three levels of OLS incidence from both cultivars were used to assess epiphytic and endophytic fungal communities, by barcoding of cultivable isolates, as well as to evaluate leaf phenolic and volatile composition. Fungal and metabolite compositions variations were detected according to the level of disease incidence. Changes were particularly noticed for OLS-tolerant cultivars, opposing to OLS-susceptible cultivars, suggesting that disease development is linked, not only to leaf fungal and metabolite composition, but also to host genotype. A set of metabolites/fungi that can act as predictive biomarkers of plant tolerance/susceptibility to OLS disease were identified. The metabolites α-farnesene and p-cymene, and the fungi Fusarium sp. and Alternaria sp. were more related to disease incidence, while Pyronema domesticum was related to the absence of disease symptoms. Cultivar susceptibility to OLS disease is then suggested to be driven by fungi, volatile and phenolic host leaves composition, and above all to plant-fungus interaction. A deeper understanding of these complex interactions may unravel plant defensive responses.