Taxanes form effective anticancer agents, which are found in the leaves and bark of the yew tree (Taxus L.). Paclitaxel (Taxol®) and related taxanes are widely used in cancer therapy. Due to the high demand of taxanes, there is strong pharmaceutical interest in evaluating unexplored population diversity as a potential genetic and biochemical resource. Three peripheral Greek Taxus baccata L. populations (Mt Cholomon, Mt Olympus and Mt Vourinos) were investigated to assess genetic (microsatellite markers), epigenetic (methylation sensitive amplified markers) and chemodiversity (targeted LC-MS/MS analysis of five major taxanes) variation. Taxane concentration varied significantly among populations and seasons. The dominant compound in needles was 10-deacetylbacatin III (DAB), ranging from 267.8 (Mt Vourinos) to 517.6 (Mt Olympus) mg kg-1 dw. Substantial genetic diversity (AR = 5.00; He = 0.537) and significant population differentiation (Fst = 0.153) were detected, while epigenetic analyses showed moderate haploid epigenetic diversity (Hepi = 0.051) and comparable levels of DNA methylation across populations. Multivariate analyses indicated clear population structuring in genetic and metabolomic profiles, whereas epigenetic variation was less strongly structured. Together, these results demonstrate pronounced spatial and seasonal variation in taxane production, alongside considerable genetic differentiation, and sufficient levels of total methylation, suggesting a potential capacity for responses to future climatic change. Our findings highlight peripheral Greek populations as valuable genetic resources for conservation and breeding aimed at sustainable taxane production.

Epigenetic diversity contributes to phenotypic plasticity and environmental responsiveness in Citrus spp. In this work, genome-wide DNA methylation was analyzed in 49 accessions representing six Citrus species, hybrids, varieties, and cultivars from the Greek National Germplasm Collection. Substantial variation in global DNA methylation was detected, while the epigenetic diversity indices did not differ significantly among taxa. The highest values were observed in Citrus × aurantium var. sinensis (orange) varieties (Pepi = 77.33%, Na = 1.55, h = 0.14, Iepi = 0.24), whereas the lowest were recorded in Citrus × aurantifolia (lime) (Pepi = 18.67%, Na = 0.37, h = 0.09, Iepi = 0.13), reflecting potential methylation restructuring impacted by hybridization and selection. Epigenetic and genetic diversity were significantly different. Principal coordinate analyses (PCoA) of epigenetic data revealed limited concordance to taxonomy, except for unmethylated loci, the latter exhibiting similar data to genetic (SSR) results in which groups reflected the taxonomic genealogy. Epigenetic and genetic distances were uncoupled, and associations between epigenetic diversity (Pepi, h, Iepi) and traits directly or indirectly related to fitness (fruit weight, dry matter content, ascorbic acid concentration), were weak. These findings indicate that epigenetic diversity represents an independent layer of variation in Citrus germplasm with potential relevance for breeding, conservation and environmental resilience.

The International Barcode of Life (iBOL) initiative is building a globally accessible DNA-based system for species identification and discovery. This paper outlines the mission and strategic priorities for the iBOL community in Europe (iBOL Europe), set in a global context. The mission of iBOL Europe is to produce, curate, and provide access to a complete DNA barcode reference library of European eukaryotic biodiversity, catalyzing species discovery and enabling comprehensive, harmonized species identification and biomonitoring, and supporting the global iBOL program. Immediate objectives include completing reference libraries for priority taxa, democratizing access to sequencing technologies, and strengthening a distributed community of practice. Key actions identified span five thematic areas: community building, sample collection and taxonomic verification, sequencing infrastructure, data management, and mainstreaming DNA-based approaches to meet societal needs. The strategy emphasizes integration with European research infrastructures to ensure long-term sustainability and resilience for biodiversity genomics in Europe.

DNA barcoding has become a cornerstone for species identification and biodiversity monitoring, enabling applications from ecological research to conservation and environmental policy. The International Barcode of Life (iBOL) provides global coordination, but national nodes are essential for implementing barcoding at scale, building local capacity and translating scientific advances into practice. This paper synthesises experiences from 20 countries (17 in Europe), drawing on a survey and a workshop conducted under the Horizon Europe Biodiversity Genomics Europe project. We examine how national nodes are initiated, governed and sustained and identify common challenges, such as defining scope, securing funding, harmonising methods and engaging stakeholders. Most nodes were initiated by research communities and operate as informal networks with heterogeneous governance and staffing models. Key priorities include constructing comprehensive DNA barcode reference libraries, aligning activities with biomonitoring needs and promoting FAIR and CARE data principles. We highlight strategies for capacity building, methodological standardisation and stakeholder engagement, alongside approaches for diversifying funding and strengthening communication. Based on these insights, we present ten practical recommendations to guide the establishment and long-term success of national DNA barcoding nodes. Strengthening these infrastructures will enhance Europe’s ability to deliver robust DNA-based biodiversity monitoring, underpin metabarcoding and metagenomic studies and contribute to global efforts in species discovery, conservation and environmental management.

The risk of climate maladaptation is increasing for numerous species, including trees. Developing robust methods to assess population maladaptation remains a critical challenge. Genomic offset approaches aim to predict climate maladaptation by characterizing the genomic changes required for populations to maintain their fitness under changing climates. In this study, we assessed the risk of climate maladaptation in European populations of English yew (Taxus baccata), a long-lived tree with a patchy distribution across Europe, the Atlas Mountains, and the Near East, where many populations are small or threatened. We found evidence suggesting local climate adaptation by analyzing 8616 SNPs in 475 trees from 29 European T. baccata populations, with climate explaining 18.1% of genetic variance and 100 unlinked climate-associated loci identified via genotype-environment association (GEA). Then, we evaluated the deviation of populations from the overall gene-climate association to assess variability in local adaptation or different adaptation trajectories across populations and found the highest deviations in low latitude populations. Moreover, we predicted genomic offsets and successfully validated these predictions using phenotypic traits assessed in plants from 26 populations grown in a comparative experiment. Finally, we integrated information from current local adaptation, genomic offset, historical genetic differentiation, and effective migration rates to show that Mediterranean and high-elevation T. baccata populations face higher vulnerability to climate change than low-elevation Atlantic and continental populations. Our study demonstrates the practical use of the genomic offset framework in conservation genetics, offers insights for its further development, and highlights the need for a population-centered approach that incorporates additional statistics and data sources to credibly assess climate vulnerability in wild plant populations.

Mitigating loss of genetic diversity is a major global biodiversity challenge1, 2, 3-4. To meet recent international commitments to maintain genetic diversity within species5,6, we need to understand relationships between threats, conservation management and genetic diversity change. Here we conduct a global analysis of genetic diversity change via meta-analysis of all available temporal measures of genetic diversity from more than three decades of research. We show that within-population genetic diversity is being lost over timescales likely to have been impacted by human activities, and that some conservation actions may mitigate this loss. Our dataset includes 628 species (animals, plants, fungi and chromists) across all terrestrial and most marine realms on Earth. Threats impacted two-thirds of the populations that we analysed, and less than half of the populations analysed received conservation management. Genetic diversity loss occurs globally and is a realistic prediction for many species, especially birds and mammals, in the face of threats such as land use change, disease, abiotic natural phenomena and harvesting or harassment. Conservation strategies designed to improve environmental conditions, increase population growth rates and introduce new individuals (for example, restoring connectivity or performing translocations) may maintain or even increase genetic diversity. Our findings underscore the urgent need for active, genetically informed conservation interventions to halt genetic diversity loss.

The high leaf morphological variability of European white oaks is largely documented in the botanical literature, and several papers have been published in the last two decades focusing on inter- and intraspecific leaf phenotypic plasticity. Studies involving landmark-based geometric morphometrics proved to be useful in highlighting relationships between leaf size and shape variation and environmental factors, phylogenetic patterns, or hybridization events. In this paper, the leaf size and shape variations of 18 populations of Quercus petraea distributed throughout a wide geographical area were analyzed by means of geometric morphometric methods (GMMs). This study involved 10 European countries and investigated the intraspecific leaf variability of Q. petraea within a wide latitudinal and longitudinal gradient. Analyses of variance for shape and centroid size were performed through Procrustes ANOVA. Multivariate analysis procedures, partial least squares method, and regression analyses were used to highlight possible patterns of covariation between leaf shape and size and geographical/environmental variables. The results revealed that the Q. petraea populations analyzed mainly differed in their leaf size, where a decrease was observed according to a north to south geographical gradient. Both leaf size and shape were found to be significantly related to latitude, and, to a lesser extent, to mean annual temperature and the leaf isotopic signature of 15N. All the other variables considered did not provide significant results. Unexpected differences observed comparing the leaf traits of geographically strictly adjacent populations suggest the involvement of local hybridization/introgression events. However, with a few exceptions, Q. petraea turned out to be quite conservative in its leaf shape and size at both the local and continental scale.

The aim of the present study was to test the central-periphery hypothesis (CPH) of evolutionary genetics in terms of genetic diversity and differentiation in Alnus glutinosa (L.) Gaertn., 1790 and Picea abies (L.) H. Karst. populations. A total of 18 nuclear SSR loci were used to evaluate genetic diversity and differentiation of two rear-edge populations of each tree species from the south-eastern edges of their distribution ranges in Greece, and two populations of each species from the core distribution area in Lithuania. Peripheral populations of A. glutinosa exhibited high genetic diversity (mean Ar = 7.99, mean He = 0.72) and low genetic differentiation (peripheral and core population FST were 0.031 and 0.008, respectively). The genetic diversity values were even higher in the peripheral populations of P. abies (mean Ar = 12.27, mean He = 0.78), while genetic differentiation was also low (peripheral and core population FST was 0.013 and 0.011, respectively). Genetic differentiation between the peripheral and core regions was also low (FST = 0.038 and G″ST = 0.262 for A. glutinosa and FST = 0.023 and G″ST = 0.172 for P. abies). Observed heterozygosity was found to be higher in peripheral populations (0.80 on average for alder and 0.84 for spruce) than in core ones (0.72 and 0.83 on average for A. glutinosa and P. abies, respectively). On the other hand, expected heterozygosity was higher in A. glutinosa core populations than in its peripheral ones (0.73 vs. 0.72 on average for core and peripheral alder populations), while spruce populations were less heterozygous in the core area (0.78 vs. 0.75 on average for peripheral and core spruce populations, respectively). These results indicate only partial agreement with CPH. Rear-edge populations showed higher genetic differentiation, while their lower genetic diversity was not significantly different from that of core populations. The investigated rear-edge populations of A. glutinosa and P. abies present valuable genetic reserves of European importance. They show local adaptation and present ample genetic variation, and their effective population size will likely be sufficient for adaptive evolution in the future. Their long-term conservation status should be prioritized.

In the present study, a combination of 17 nuclear and four chloroplast microsatellites were used to identify polymorphisms among 224 Citrus accessions maintained at the ex-situ ELGO-DIMITRA germplasm collection, mainly located in Chania, Greece. The nuclear marker data set revealed 109 unique genetic profiles with a mean gene diversity of 0.63, while the chloroplast DNA data set revealed 28 haplotypes between all accessions. A Bayesian genetic structure analysis was used to assign accessions into groups, and a dendrogram based on chloroplast markers allowed the maternal lineage identification of multiple hybrids. A few indigenous accessions exhibited notable genetic differences compared to the evaluated international counterparts (citron: ‘Cretan Smooth’, mandarin: ‘Common Chios’, lemon: ‘Karystini Xylokastrou’/‘Vakalou’/‘Helen’, lime: ‘Pastolemono Chiou’/‘Glykolemono’, greek bergamots, sweet orange: ‘Botsato Artas’). The rest of them presented highly similar or indistinguishable genetic profiles with known accessions. These results are expected to facilitate further exploration of Citrus genotypes maintained in Greece and assist in efficient conservation and design of breeding programs.

Genetic monitoring of populations currently attracts interest in the context of the Convention on Biological Diversity but needs long-term planning and investments. However, genetic diversity has been largely neglected in biodiversity monitoring, and when addressed, it is treated separately, detached from other conservation issues, such as habitat alteration due to climate change. We report an accounting of efforts to monitor population genetic diversity in Europe (genetic monitoring effort, GME), the evaluation of which can help guide future capacity building and collaboration towards areas most in need of expanded monitoring. Overlaying GME with areas where the ranges of selected species of conservation interest approach current and future climate niche limits helps identify whether GME coincides with anticipated climate change effects on biodiversity. Our analysis suggests that country area, financial resources and conservation policy influence GME, high values of which only partially match species' joint patterns of limits to suitable climatic conditions. Populations at trailing climatic niche margins probably hold genetic diversity that is important for adaptation to changing climate. Our results illuminate the need in Europe for expanded investment in genetic monitoring across climate gradients occupied by focal species, a need arguably greatest in southeastern European countries. This need could be met in part by expanding the European Union's Birds and Habitats Directives to fully address the conservation and monitoring of genetic diversity.

Honeysuckle azalea (Rhododendron luteum) has only a single population occurrence in Greece, on Lesvos Island of the north-eastern Aegean Sea. The genetic diversity of this population was studied in a population of n = 37 individuals randomly sampled in a transect spanning between the highest and lowest natural altitudinal distribution limits in Mt. Ordymnos, SW Lesvos. A modified DNA extraction and isolation protocol was used to overcome problems of DNA quality due to secondary metabolite activity. Genetic variation was investigated based on molecular Inter Simple Sequence Repeat (ISSR) markers. Results showed the presence of a sufficient amount of genetic diversity for the maintenance of adaptive potential. Genetic diversity was lower but comparable to that of other Rhododendron species sampled from the centre of their natural distribution, despite the relatively small population size, negative anthropogenic pressure and population isolation due to the island environment. Some structuring of genetic diversity was indicated based on a PCoA analysis and the genetic distance dendrogram, while spatial autocorrelation was highly significant. Results point towards the need to assign a protection status to the whole area of the species’ natural distribution on Lesvos Island. Moreover, it is proposed that an in situ Gene Conservation Unit (GCU) be established in the core of this population in Lesvos as part of the Network of the European Forest Genetic Resources Programme, while the establishment of ex situ conservation is also advised.

High-depth whole-genome resequencing of 53 diverse fig tree genotypes yielded a rich dataset of genetic variants. We successfully identified 5,501,460 single-nucleotide polymorphisms (SNPs) and 1,228,537 insertions and deletions (InDels), providing a high-density and excellent-quality genetic map of the fig tree. We also performed a detailed population structure analysis, dividing the 53 genotypes into three geographical groups and assessing their genetic diversity and divergence. Analysis of structural variants (SVs) and copy number variations (CNVs) revealed their potential functional impact, particularly in plant-pathogen interaction and secondary metabolism. Metabolomic fingerprinting of fig genotypes uncovered extensive variation in primary metabolites and polyphenolic compounds, highlighting the influence of genotype on fruit quality traits such as nutritional content and bioactive compound composition. The genome-wide association study (GWAS) identified critical SNPs associated with fruit quality and morphological features. The discovery of significant candidate genes, such as AGL62, GDSL, and COBRA-like protein 4 genes, offers promising targets for marker-assisted selection and genome editing approaches to improve fig fruit morphological and quality traits. This extensive genomic analysis of fig trees enhances our understanding of the genetic basis of important agronomic traits and provides a rich resource for future research in this economically and nutritionally significant fruit.

Forest ecosystems are of global importance, ecologically, economically and culturally. However, despite their fundamental role in mitigating the worst effects of climate change, to date there have been surprisingly few resources devoted to defining, conserving and planning resilient forests for the future. Progress in this field of research, which requires international and interdisciplinary cooperation, collaboration and communication, was presented and discussed at the second biannual conference of the European Research Group, Evoltree ( https://www.evoltree.eu ). Over four days more than 140 scientists met to share developments and to discuss forest ecology, genetics, genomics and evolution with a focus on realising “Resilient Forests for the Future”. From examining evolutionary dynamics and using the past to understand future responses, to evaluating breeding approaches and the sustainable use of forest genetic resources, the conference addressed critical themes with relevance to this topic. The role of genomics in conservation, investigation of biotic interactions and identifying climate resilient forests were also explored. Finally, innovative methods and approaches which promise to increase the scale and speed with which forest evolutionary research can progress were introduced and evaluated. The Evoltree network and conference series provides invaluable opportunities to share knowledge and increase collaboration on forest genetic research, the need for which has never been greater or more urgent.

Scientifically informed decisions for the long-term conservation of extant genetic diversity should combine in situ and ex situ conservation methods. The aim of the present study was to assess if a progeny plantation consisting of several open pollinated (OP) families and established for breeding purposes can also serve as an ex situ conservation plantation, using the case study of a Lithuanian progeny trial of Alnus glutinosa, a keystone species of riparian ecosystems that warrants priority conservation actions. We employed 17 nuclear microsatellite (Simple Sequence Repeat) markers and compared the genetic diversity and copy number of the captured alleles of 22 OP progeny families from this plantation, with 10 wild A. glutinosa populations, originating from the two provenance regions of the species in Lithuania. We conclude that the progeny plantation could be used as an ex situ plantation for the A. glutinosa populations from the first provenance region (represented by eight genetic conservation units (GCU)). Based on the present study’s results, we can expect that the A. glutinosa progeny plantation harbors enough genetic diversity of wild A. glutinosa populations from the first provenance region. This progeny plantation can serve as a robust ex situ collection containing local alleles present in at least one wild population with at least 0.05 frequency with 25 replications.

The genetic diversity of populations is the ultimate source for adaptation and survival under changing environmental conditions. Genetic monitoring of temporal genetic diversity changes in autochthonous forest tree populations of key ecosystems species allows us to predict and mitigate potentially harmful changes of forests adaptability. The aim of the present study was to assess the genetic diversity of autochthonous protected A. glutinosa populations, to compare the genetic diversity between maternal and progeny generations, in a distribution area that is known to harbour extensive genetic diversity, and to assess if there is an impact on genetic diversity when forest management practices to promote natural regeneration of mature stands are introduced. The genetic diversity of ten A. glutinosa populations from Lithuania was studied using 20 nuclear SSR primers. In total, 597 individuals (300 juvenile and 297 mature trees) were investigated. In half of the studied black alder GCUs, forest management to promote natural regeneration was carried out. The present study revealed high genetic diversity (average population Ar was 5.77, Ho and He–0.70) and low, but a significant population differentiation of studied A. glutinosa populations. The lack of significant genetic differences among different generations (population cohorts), is a strong indication that the black alder GCUs in Lithuania form an excellent platform for the protection of the species’ genetic diversity in the country.

Delivering material selected for breeding purposes into the wild in the context of sustainable forest management might reduce the levels of genetic diversity of future forests in comparison to that of natural populations. Another consequence might be a reduction of their resilience under uncertain future climatic and socio-economic conditions if these new populations lack adaptability. Despite the long tradition of breeding activities in Europe, there is still a need to assess the impact of genetically enriched material on forests’ resilience. In this study, we address (1) the genetic diversity of selected material compared to its wild ancestors, and (2) how to enrich breeding material to support forests’ resilience under changing socio-environmental conditions. We analysed 16 study cases of selected material delivered from breeding activities in four European forest tree species (Pinus halepensis Mill., Pinus nigra J.F. Arnold, Pinus pinaster Ait. and Populus nigra L.) with different levels of breeding. To answer these two questions, we first assessed and compared the genetic diversity of selected material versus natural populations using both putatively neutral and adaptive (based on diverging selection) Single Nucleotide Polymorphisms (SNPs). We then suggest how to enrich these populations for resilience under future climatic conditions by defining a core collection for each species including material from populations that will likely disappear under future conditions. Thanks to the large SNP datasets available for our focal species, we were able to detect some trends in our data. Expected and observed heterozygosity values for selected populations were almost always identical. The selected material showed small but significant genetic differentiation from their original population and their inbreeding coefficient was generally lower. However, the level of genetic improvement (i.e. low vs high) was not correlated with the observed genetic differences between selected material and natural populations.The genetic characterization of natural populations distributed across the species range, and the future projection of their range stability, made it possible to identify core-collections that would significantly enrich breeding populations under uncertain future environmental conditions.

Forest species in the course of their evolution have experienced several environmental challenges, which since historic times include anthropogenic pollution. The effects of pollution on the genetic and epigenetic diversity in black pine (Pinus nigra) forests were investigated in the Amyntaio - Ptolemais - Kozani Basin, which has been for decades the largest lignite mining and burning center of Greece, with a total installed generating capacity of about 4.5 GW, operating for more than 70 years and resulting in large amounts of primary air pollutant emissions, mainly SO2, NOx and PM10. P. nigra, a biomarker for air pollution and a keystone species of affected natural ecosystems, was examined in terms of phenology (cone and seed parameters), genetics (283 AFLP loci) and epigenetics (606 MSAP epiloci), using two populations (exposed to pollution and control) of the current (mature trees) and future (embryos) stand. It was found that cone, seed, as well as genetic diversity parameters, did not show statistically significant differences between the exposed population and the control. Nevertheless, statistically significant differences were detected at the population epigenetic level. Moreover, there was a further differentiation regarding the intergenerational comparison: while the epigenetic diversity does not substantially change in the two generations assessed in the control population, epigenetic diversity is significantly higher in the embryo population compared to the parental stand in the exposed population. This study sheds a light to genome dynamics in a forest tree population exposed to long term atmospheric pollution burden and stresses the importance of assessing both genetics and epigenetics in biomonitoring applications.

Olive tree (Olea europaea L. subsp. europaea var. europaea) is one of the most important species of the Mediterranean region and one of the most ancient species domesticated. The availability of whole genome assemblies and annotations of olive tree cultivars and oleaster (O. europaea subsp. europaea var. sylvestris) has contributed to a better understanding of genetic and genomic differences between olive tree cultivars. However, compared to other plant species there is still a lack of genomic resources for olive tree populations that span the entire Mediterranean region. In the present study we developed the most complete genomic variation map and the most comprehensive catalog/resource of molecular variation to date for 89 olive tree genotypes originating from the entire Mediterranean basin, revealing the genetic diversity of this commercially significant crop tree and explaining the divergence/similarity among different variants. Additionally, the monumental ancient tree 'Throuba Naxos' was studied to characterize the potential origin or routes of olive tree domestication. Several candidate genes known to be associated with key agronomic traits, including olive oil quality and fruit yield, were uncovered by a selective sweep scan to be under selection pressure on all olive tree chromosomes. To further exploit the genomic and phenotypic resources obtained from the current work, genome-wide association analyses were performed for 23 morphological and two agronomic traits. Significant associations were detected for eight traits that provide valuable candidates for fruit tree breeding and for deeper understanding of olive tree biology.

The genetic relationships between Greek wild olive tree populations and cultivars were investigated. A total of 219 wild genotypes and 67 cultivar genotypes were analyzed by employing 10 SSR markers. Data evidenced that the wild populations exhibited high levels of genetic diversity and exclusively host 40% of the total number of alleles detected. Inbreeding was observed within populations, probably as a consequence of their fragmented spatial distribution. The genetic differentiation between cultivars and wild individuals, as well as within wild populations, was low. Nevertheless, three gene pools of wild trees were detected, corresponding to the geographical areas of Northeastern Greece, Peloponnese-Crete and Epirus. Most cultivars clustered in a separate group, while the rest of them formed a heterogenous group with membership coefficients akin to the three wild olive clusters. Regarding the history of olive cultivation in Greece, bidirectional gene flow was detected between populations of Peloponnese-Crete and the gene pool that composes some of Greece’s most important cultivars, such as "Koroneiki” and “Mastoidis”, which is inferred as an indication of a minor domestication event in the area. A strategy for the protection of Greek-oriented olive genetic resources is proposed, along with suggestions for the utilization of the genetically diverse wild resources with regard to the introgression of traits of agronomical interest to cultivars.

This paper investigates leaf morphology variation of the strawberry tree (Arbutus unedo) within and between two natural contrasting populations of significant latitudinal difference (Kassandreia, Chalkidiki and Ancient Olympia, Peloponnese). This study employed 11 leaf size and shape parameters, recorded by image processing and analyzing software. The results showed that in the measurements of central tendency (parameter means) the northern population of Kassandreia presented the highest values, while in contrast the highest values in the measurements of spread were found in the southern population of Ancient Olympia. Moreover, statistically significant differences between populations were detected in leaf size, but not in leaf shape parameters. Results are discussed in the context of their value in studying quantitative population differentiation and laying the basis of more advanced studies.