Centennial olive trees as a reservoir of genetic diversity

Background and Aims

Genetic characterization and phylogenetic analysis of the oldest trees could be a powerful tool both for germplasm collection and for understanding the earliest origins of clonally propagated fruit crops. The olive tree (Olea europaea L.) is a suitable model to study the origin of cultivars due to its long lifespan, resulting in the existence of both centennial and millennial trees across the Mediterranean Basin.

Methods

The genetic identity and diversity as well as the phylogenetic relationships among the oldest wild and cultivated olives of southern Spain were evaluated by analysing simple sequence repeat markers. Samples from both the canopy and the roots of each tree were analysed to distinguish which trees were self-rooted and which were grafted. The ancient olives were also put into chronological order to infer the antiquity of traditional olive cultivars.

Key Results

Only 9·6 % out of 104 a priori cultivated ancient genotypes matched current olive cultivars. The percentage of unidentified genotypes was higher among the oldest olives, which could be because they belong to ancient unknown cultivars or because of possible intra-cultivar variability. Comparing the observed patterns of genetic variation made it possible to distinguish which trees were grafted onto putative wild olives.

Conclusions

This study of ancient olives has been fruitful both for germplasm collection and for enlarging our knowledge about olive domestication. The findings suggest that grafting pre-existing wild olives with olive cultivars was linked to the beginnings of olive growing. Additionally, the low number of genotypes identified in current cultivars points out that the ancient olives from southern Spain constitute a priceless reservoir of genetic diversity.     

K(+) starvation inhibits water-stress-induced stomatal closure

The effect of potassium starvation on stomatal conductance was studied in olive trees and sunflower plants, two major crops with greatly differing botanical characteristics. In both species, K(+) starvation inhibited water-stress-induced stomatal closure. In olive trees, potassium starvation favoured stomatal conductance and transpiration, as well as inhibiting shoot growth, in the three cultivars studied: 'Lechín de Granada', 'Arbequina' and 'Chetoui'. However, 'Lechín de Granada' - generally considered more drought-tolerant than 'Arbequina' and 'Chetoui' - proved less susceptible to potassium starvation. Results for olive trees also suggest genetic variability in olive cultivars in relation to potassium requirements for stem growth and the regulation of water transpiration. The results obtained suggest that inhibition of the stomatal closure mechanism produced by moderate potassium starvation is a widespread plant physiological disorder, and may be the cause of tissue dehydration in many water-stressed crops.     

High Genetic Diversity Detected in Olives beyond the Boundaries of the Mediterranean Sea

Background

Olive trees (Olea europaea subsp. europaea var. europaea) naturally grow in areas spanning the Mediterranean basin and towards the East, including the Middle East. In the Iranian plateau, the presence of olives has been documented since very ancient times, though the early history of the crop in this area is shrouded in uncertainty.

Methods

The varieties presently cultivated in Iran and trees of an unknown cultivation status, surviving under extreme climate and soil conditions, were sampled from different provinces and compared with a set of Mediterranean cultivars. All samples were analyzed using SSR and chloroplast markers to establish the relationships between Iranian olives and Mediterranean varieties, to shed light on the origins of Iranian olives and to verify their contribution to the development of the current global olive variation.

Results

Iranian cultivars and ecotypes, when analyzed using SSR markers, clustered separately from Mediterranean cultivars and showed a high number of private alleles, on the contrary, they shared the same single chlorotype with the most widespread varieties cultivated in the Mediterranean.

Conclusion

We hypothesized that Iranian and Mediterranean olive trees may have had a common origin from a unique center in the Near East region, possibly including the western Iranian area. The present pattern of variation may have derived from different environmental conditions, distinct levels and selection criteria, and divergent breeding opportunities found by Mediterranean and Iranian olives.These unexpected findings emphasize the importance of studying the Iranian olive germplasm as a promising but endangered source of variation.     

Genetic structure of wild and cultivated olives in the central Mediterranean basin

BACKGROUND AND AIMS: Olive cultivars and their wild relatives (oleasters) represent two botanical varieties of Olea europaea subsp. europaea (respectively europaea and sylvestris). Olive cultivars have undergone human selection and their area of diffusion overlaps that of oleasters. Populations of genuine wild olives seem restricted to isolated areas of Mediterranean forests, while most other wild-looking forms of olive may include feral forms that escaped cultivation. METHODS: The genetic structure of wild and cultivated olive tree populations was evaluated by amplified fragment length polymorphism (AFLP) markers at a microscale level in one continental and two insular Italian regions. KEY RESULTS: The observed patterns of genetic variation were able to distinguish wild from cultivated populations and continental from insular regions. Island oleasters were highly similar to each other and were clearly distinguishable from those of continental regions. Ancient cultivated material from one island clustered with the wild plants, while the old plants from the continental region clustered with the cultivated group. CONCLUSIONS: On the basis of these results, we can assume that olive trees have undergone a different selection/domestication process in the insular and mainland regions. The degree of differentiation between oleasters and cultivated trees on the islands suggests that all cultivars have been introduced into these regions from the outside, while the Umbrian cultivars have originated either by selection from local oleasters or by direct introduction from other regions.     

Genetic diversity and relationships of wild and cultivated olives in Turkey

In the present study, we proposed to determine the genetic diversity and relationships between local cultivars and wild olive trees from three important olive-growing regions, i.e., Marmara, Aegean, and Mediterranean, of Turkey. This is the first known large-scale molecular study to investigate the relationships between local cultivars and wild olives from the eastern Mediterranean basin. Two hundred and four oleaster trees and 27 cultivars were sampled to represent molecular diversity. We used 11 simple sequence repeat and 13 sequence-related amplified polymorphism markers to assess genetic variations and inter-relationships among the samples. The results of the analysis showed differences in the levels of allelic composition and heterozygosity between cultivated and wild olive trees. The observation of a high proportion of a certain wild-type genetic background in the cultivars may indicate the former use of local wild trees in olive domestication in Turkey, a possible autochthonal origin of cultivars. “Gemlik” was found to be the most common olive cultivar in the Marmara region and most of the wild olive samples from this region may be feral forms derived from cultivar seed spreading. The information obtained from this study can help to assist the management of an olive collection and sheds some light on the origin of Turkish olive cultivars.     

Molecular identification of Greek olive (Olea europaea) cultivars based on microsatellite loci

Olea europaea is one of the oldest species of domesticated trees. We used microsatellite markers for fingerprinting and for evaluation of genetic similarity and structure of 26 Greek olive cultivars, which cover most of the olive cultivation regions of Greece, including previously undescribed denominations from northern Greece. Eighty-one alleles were revealed with six SSR loci that were selected as most informative of 10 SSR primers that were initially investigated. The number of alleles per locus varied from 7 to 20 (mean, 13.5). Heterozygosity ranged from 0.240 at locus DCA-3 to 0.826 at locus UDO99-9, with a mean value of 0.600. Analysis of 104 trees representing 26 denominations (four trees per denomination) revealed 26 distinct SSR profiles, indicating 26 olive cultivars; no intracultivar variability was observed. Genetic and geographic distances were not significantly correlated, based on the Mantel test. These SSR loci allowed unequivocal identification of all the cultivars and will be useful for future breeding and olive germplasm management efforts.     

Substantial genetic diversity in cultivated Moroccan olive despite a single major cultivar: a paradoxical situation evidenced by the use of SSR loci

To assess the genetic diversity in Moroccan cultivated olive, Olea europaea L. subsp. europaea, we performed molecular analysis of olive trees sampled in four geographic zones representing all areas of traditional olive culture. The analysis of 215 trees using 15 simple sequence repeat (SSR) loci revealed 105 alleles distributed among 60 SSR profiles. The analysis of chloroplast deoxyribonucleic acid polymorphism for these 60 olive genotypes allowed to identify four chlorotypes: 42 CE1, one CE2, nine COM1 and eight CCK. Among the 60 SSR profiles, 52 corresponded to cultivated olive trees for which neither denomination nor characterisation is available. These local olive genotypes displayed a spatial genetic structuring over the four Moroccan geographic zones (northwest, north centre, Atlas and southwest), as pairwise Fst values ranged from 0.0394 to 0.1383 and varied according to geographic distance. As single alleles detected in local olive were also observed in Moroccan oleaster populations, results suggest that plant material was mainly selected from indigenous populations. The assumption that Picholine marocaine cultivar is a multi-clonal cultivar was not supported by our data because we found a single genotype for 112 olive trees representing 31 to 93% of the olives sampled locally in the 14 different areas. Picholine marocaine and the few other named cultivars do not seem to belong to the same gene pools as the unnamed genotypes cultivated only locally. The situation is paradoxical: a substantial genetic diversity in Moroccan olive germplasm, probably resulting from much local domestication, but a single cultivar is predominant.     

A new avenue for classification and prediction of olive cultivars using supervised and unsupervised algorithms

Various methods have been used to identify cultivares of olive trees; herein we used different bioinformatics algorithms to propose new tools to classify 10 cultivares of olive based on RAPD and ISSR genetic markers datasets generated from PCR reactions. Five RAPD markers (OPA0a21, OPD16a, OP01a1, OPD16a1 and OPA0a8) and five ISSR markers (UBC841a4, UBC868a7, UBC841a14, U12BC807a and UBC810a13) selected as the most important markers by all attribute weighting models. K-Medoids unsupervised clustering run on SVM dataset was fully able to cluster each olive cultivar to the right classes. All trees (176) induced by decision tree models generated meaningful trees and UBC841a4 attribute clearly distinguished between foreign and domestic olive cultivars with 100% accuracy. Predictive machine learning algorithms (SVM and Naïve Bayes) were also able to predict the right class of olive cultivares with 100% accuracy. For the first time, our results showed data mining techniques can be effectively used to distinguish between plant cultivares and proposed machine learning based systems in this study can predict new olive cultivars with the best possible accuracy.     

Effect of Inoculum Density on Verticillium Wilt Incidence in Commercial Olive Orchards

Verticillium wilt, caused by Verticillium dahliae Kleb., is presently the most destructive disease of olive, particularly in Andalucía (southern Spain). ‘Picual’ and ‘Arbequina’ are the dominant cultivars being planted in Spain. Both cultivars are highly susceptible to the defoliating pathotype of V. dahliae when artificially inoculated by root‐dipping or stem injection. Conversely, ‘Arbequina’ is considered more resistant than ‘Picual’ based on field observations and farmer's experience. In this study, the differential reaction between of cultivars was confirmed by surveys of naturally infested orchards with different inoculum densities of the pathogen. The average percentage of affected olive trees of ‘Picual’ was 60.2%, while only 13.1% of trees of ‘Arbequina’ showed disease symptoms. Overall, the pathogen caused extensive wilting of branches and defoliation on the trees of ‘Picual’, whereas ‘Arbequina’‐infected trees showed chlorotic symptoms and slight defoliation. The relationship between inoculum density and disease incidence fit a logarithmic function for both cultivars. The percentage of affected trees of ‘Arbequina’ per year increased linearly (y = 0.3559x, R² = 0.5652, and P = 0.0195) with the inoculum density in the soil, whereas this relationship was not observed for the ‘Picual’. Planting density had no effect on disease incidence for any of the two cultivars.     

Innovative protocol for “<Emphasis Type="Italic">ex vitro</Emphasis> rooting” on olive micropropagation

The commercial micropropagation of olive trees is currently limited by the production cost. An ex vitro method for olive microshoot rooting could reduce both the production cost per plant and the propagation time. In this study a successful ex vitro rooting protocol tested on seven olive cultivars is reported. The explants of cv. Maurino were collected from fifth, sixth, and seventh proliferative subcultures carried out on MSM medium, while for the other cultivars the explants were collected from only seventh proliferative subculture. Continuous light during the rooting phase was a prerequisite for the success of the ex vitro protocol. The best source of microshoots for a high rooting percentage was the seventh proliferative subculture. Cvs. Coratina, Maremmano, Maurino, Picholine, and S. Francesco showed high rooting percentages with a range of 62–76%; whereas for cvs. Correggiolo and Frantoio the experimental conditions need to be optimised. Up to 90% of the rooted microplants survived, and continuous growth of shoots was subsequently observed. The proposed protocol can be easily applied to several different olive cultivars to produce microplants by commercial laboratories. The approach makes olive micropropagation in the nursery industry both possible and profitable.     

Observation of eight ancient olive trees (Olea europaea L.) growing in the Garden of Gethsemane

For thousands of years, olive trees (Olea europaea L.) have been a significant presence and a symbol in the Garden of Gethsemane, a place located at the foot of the Mount of Olives, Jerusalem, remembered for the agony of Jesus Christ before his arrest. This investigation comprises the first morphological and genetic characterization of eight olive trees in the Garden of Gethsemane. Pomological traits, morphometric, and ultrastructural observations as well as SSR (Simple Sequence Repeat) analysis were performed to identify the olive trees. Statistical analyses were conducted to evaluate their morphological variability. The study revealed a low morphological variability and minimal dissimilarity among the olive trees. According to molecular analysis, these trees showed the same allelic profile at all microsatellite loci analyzed. Combining the results of the different analyses carried out in the frame of the present work, we could conclude that the eight olive trees of the Gethsemane Garden have been propagated from a single genotype.     

Changes in Ribonuclease and Glucose-6-Phosphate Dehydrogenase Activities Induced by Beet Necrotic Yellow Vein Virus in Sugar Beet

Activities of host ribonucleases and glucose-6-phosphate dehydrogenase were studied in three cultivars (Monosvalof, Steffi and Rimini) of sugar beet differing in their resistance to beet necrotic yellow vein virus (BNYVV). No differences were found in the susceptibility of cultivars to BNYVV between mechanically inoculated and Polymyxa betae (a natural fungal vector of the virus) infected plants, but the culmination of reproduction curves of BNYVV in mechanically inoculated plants was observed one week earlier than in plants inoculated by means of P. betae. The activities of ribonucleases corresponded with virus multiplication. In roots, activities of ribonucleases reached a maximum at day 7; in leaves, maximum activity was found at day 21 in cv. Monosvalof, and at day 14 in cv. Steffi. The relatively resistant cultivar Rimini showed much lower activities. The activity of glucose-6-phosphate dehydrogenase was only slightly increased at the time of culmination of the BNYVV reproduction curve in cvs. Monosvalof and Steffi. This revised version was published online in June 2006 with corrections to the Cover Date.     

25份槭属优良种质资源亲缘关系的ISSR分析

槭属植物是世界园林绿化中的重要植物种类,种质资源丰富且大多数种类具有重要的观赏价值。针对目前我国槭属植物杂交育种工作中面临的品种混杂不清、亲缘状况不明等情况,该研究采用ISSR分子标记对槭属25份植物材料进行了亲缘关系分析。结果表明:选用12条扩增带型清晰且重复性好的引物共获得84条谱带,其中81条呈多态性,多态性比例(PPB)达96.43%,表明槭属植物遗传多样性较高。25份槭属植物材料的遗传相似性系数介于0.405与0.952之间,平均值为0.627,表明不同品种或物种之间遗传相似性系数变化较大。根据Nei遗传相似性系数,在0.578处,UPGMA结果将25份植物材料分为2个类群,其中鸡爪槭品种(或变种)聚为一类,显示了各品种(或变种)之间具有较高的亲缘关系,其余槭属植物则聚为类群II;在0.646处,可进一步分为6个亚类群,部分鸡爪槭品种间表现出了叶形、叶色等表型形状与其遗传关系的相关性。研究未发现鸡爪槭品种(或变种)的亲缘关系与地理分布存在相关性。我国槭树资源丰富,但目前我国对槭树新品种的开发及选育工作仍十分薄弱,建议采取自行选育结合国外引进新品种的方式,丰富我国的槭树种质资源。     

Identification of the Worldwide Olive Germplasm Bank of Córdoba (Spain) using SSR and morphological markers

Olive is one of the most ancient crop plants and the World Olive Germplasm Bank of Cordoba (WOGBC), Spain, is one of the world’s largest collections of olive germplasm. We used 33 SSR (Simple Sequence Repeats) markers and 11 morphological characteristics of the endocarp to characterise, identify and authenticate 824 trees, representing 499 accessions from 21 countries of origin, from the WOGBC collection. The SSR markers exhibited high variability and information content. Of 332 cultivars identified in this study based on unique combinations of SSR genotypes and endocarp morphologies, 200 were authenticated by genotypic and morphological markers matches with authentic control samples. We found 130 SSR genotypes that we considered as molecular variants because they showed minimal molecular differences but the same morphological profile than 48 catalogued cultivars. We reported 15 previously described and 37 new cases of synonyms as well as 26 previously described and seven new cases of homonyms. We detected several errors in accession labelling, which may have occurred at any step during establishment of plants in the collection. Nested sets of 5, 10 and 17 SSRs were proposed to progressively and efficiently identify all of the genotypes studied here. The study provides a useful protocol for the characterisation, identification and authentication of any olive germplasm bank that has facilitated the establishment of a repository of true-to-type cultivars at the WOGBC.     

Advances in the pollination biology of olive (Olea europaea L.)

The olive originated in the Mediterranean region, and is most extensively cultivated oleiferous tree species in the world due to its high economic value. The olive has been introduced to China for more than 50 years, and some cultivars have showed good ecological suitability. The plantation of olive in China is increasing rapidly. However, many olive trees during the fruiting age showed the low fruit-setting rates and unstable fruit yields. Studies on pollination biology of olive are important to improve olive fruit-setting rates, genetic resources, and clonal selection and cross-breeding. Overseas much have been done about studies on pollination biology of olive, which are still scarce in China. In this paper, we presented a review of the recent advances in the pollination biology of olive, with the emphasis on blossom phenological characteristics, floral morphology, pollen germination, mating system, as well as their impacts on the fruit set of olive. The future researches in China were subsequently suggested as follows: (1) Strengthen the basic researches of olive pollination biology, including the ratio between monoecious and andromonoecious flowers in main introduced cultivars, the mechanisms for the maintenance of the olive sexual system, and the functional differences between monoecious and andromonoecious flowers and their relationship with wind-pollination, (2) Both field artificial pollination and molecular technology should be combined to elucidate the olive breeding system of cultivars, to explore the genetic and physiological mechanisms of self-infertility and cross-pollination, and to find the determinative factors of affecting the pollination compatibility of various cultivars, and (3) Studies on both olive pollination biology and breeding system should be combined to analyze comprehensively the effects of pollination and fertilization processes on fruit setting and early fruit development.     

26个川茶花品种亲缘关系的ISSR分析

采用ISSR分子标记,对重庆南山植物园中26个品种的川茶花古树进行了ISSR遗传多样性分析。选用14条扩增带型清晰且重复性好的引物共获得166条谱带,其中140条呈多态性,多态性比例(PPB)为84.34％。根据Nei-Li遗传相似性系数在0.708处,UPGMA结果将26个品种分为5个类群,在0.726处可进一步分为10个亚类群;26个川茶花品种的遗传相似性系数介于0.615和0.913之间,平均值为0.704,表明品种间亲缘关系较近。其中牡丹茶与花牡丹之间遗传相似性系数最大,为0.913,表明牡丹茶可能为花牡丹的芽变品种。川渝地区山茶古树资源丰富,但在古树的保护上也面临诸多问题,建议采取相应的措施加以保护。     

Phenological and aeropalynological survey in an olive orchard in Umbria (Central Italy)

The olive tree Olea europaea L. is a resource of notable value from an economic and landscape point of view in Central Italy. This study examined two cultivars (Giarraffa and Ascolana) grown in an associative stand in an experimental olive orchard, to verify the possibility of introducing new olive cultivars into Umbria. The analyses were carried out at three different altitudes in the olive orchard following criteria used for non-homogeneous samplings in order to minimize the effect due to steepness. Since the number of trees of the two cultivars is different, the sample sizes were different for the two cultivars. Phenological observations of the above mentioned cultivars and the evaluation of the pollen flow, done by using a portable pollen trap inside the olive orchard, were carried out over two seasons (1998-1999). The start of initial phenological phases differed in the two cultivars, but the differences became less evident during phases of anthesis. In aeropalynological respect, it appears that, in a hill species such as the olive tree, the flowering is correlated with altitude. Comparing the aeropalynological data from the distant pollen trap and those collected in the olive orchard, it is clear that the periods of pollen release are very similar in the two cultivars, and there is a clear synchronism in the peak pollen release. It is concluded that in Central Italy the pollen grains of Giarraffa cultivar are well compatible with the Ascolana cultivar from a phenological and aeropalynological point of view.     

Genetic diversity and gene flow between the wild olive (oleaster, Olea europaea L.) and the olive: several Plio-Pleistocene refuge zones in the Mediterranean basin suggested by simple sequence repeats analysis

Aim The oleaster is believed to have originated in the eastern Mediterranean, implying that those in the western Mediterranean basin could be feral. Several studies with different molecular markers (isozymes, random amplified polymorphic DNA, amplified fragment length polymorphism) have shown a cline between the eastern and the western populations, which supports this hypothesis. To reconstruct the post‐glacial colonization history and establish a relationship between olive and oleaster populations in the Mediterranean basin, analyses were carried out on the genetic variation of chloroplast DNA (chlorotype) and at 12 unlinked simple sequence repeat (SSR) loci, sampling a total of 20 oleaster groves. Location This is the first known large‐scale molecular study of SSR loci based on samples of both oleasters and cultivars from the entire Mediterranean basin. Methods Samples were taken from 166 oleasters in 20 groves of modern populations, and 40 cultivars to represent molecular diversity in the cultivated olive. The Bayesian method and admixture analysis were used to construct the ancestral populations (RPOP; reconstructed panmictic oleaster populations) and to estimate the proportion of each RPOP in each tree. If one tree can be assigned to two or more RPOPs, it can be regarded as a product of hybridization between trees from different populations (i.e. admix origin). Results On this first examination of the SSR genetic diversity in the olive and oleaster, it was found to be structured in seven RPOPs in both eastern and western populations. Based on different population genetic methods, it was shown that: (1) oleasters are equally present in the eastern and the western Mediterranean, (2) are native, and (3) are not derived from cultivars. Chlorotypes (one and three in the eastern and western Mediterranean, respectively) revealed fruit displacement for the oleasters. Main conclusions Oleaster genetic diversity is divided into seven regions that could overlay glacial refuges. The gradient, or cline, of genetic diversity revealed by chloroplast and SSR molecular markers was explained by oleaster recolonization of the Mediterranean basin from refuges after the last glacial event, located in both eastern and western regions. It is likely that gene flow has occurred in oleasters mediated by cultivars spread by human migration or through trade. Animals may have helped spread oleasters locally, but humans have probably transported olives but not oleaster fruits over long distances. We found that cultivars may have originated in several RPOPs, and thus, some may have a more complex origin than expected initially.     

Intra-specific genetic diversity in wild olives (Olea europaea ssp cuspidata) in Hormozgan Province, Iran

Wild olive (O. europaea ssp cuspidata) plants grow in various regions of Iran and are expected to have considerable genetic diversity due to adaptation to the various environmental conditions. We examined the genetic diversity of four populations of wild olive growing in Hormozgan Province located in southern Iran by using 30 RAPDs and 10 ISSR markers. The mean value of polymorphism for RAPD loci was 73.71%, while the value for ISSR loci was 81.74%. The Keshar population had the highest value of intra-population polymorphism for both RAPD and ISSR loci (66.86 and 62.71%, respectively), while the Tudar population had the lowest values (20.35 and 28.81%, respectively). Similarly, the highest and lowest number of effective alleles, Shannon index and Nei's genetic diversity were also found for these two populations. The highest value of H(pop)/H(sp) within population genetic diversity for RAPD and ISSR loci was found for the Keshar population (H(pop) = 0.85 and H(sp) = 0.90). OPA04-750, OPA13-650 and OPA02-350 RAPD bands were specific for Tudar, Bondon and Keshar populations, respectively, while no specific ISSR bands were observed. Analysis of molecular variance as well as the pairwise F(ST) test showed significant differences for RAPD and ISSR markers among the populations. The NJ and UPGMA trees also separated the wild olive populations from each other, indicating their genetic distinctness. UPGMA clustering of the four wild olive populations placed the Tudar population far from the other populations; Keshar and Bokhoon population samples revealed more similarity and were grouped together. We conclude that there is high genetic diversity among O. europaea ssp cuspidata populations located in southern Iran. We also found RAPD and ISSR markers to be useful molecular tools to discriminate and evaluate genetic variations in wild olive trees.     

Introducing cultivated trees into the wild: Wood pigeons as dispersers of domestic olive seeds

Animals may disperse cultivated trees outside the agricultural land, favoring the naturalization or, even, the invasiveness of domestic plants. However, the ecological and conservation implications of new or unexplored mutualisms between cultivated trees and wild animals are still far from clear. Here, we examine the possible role of an expanding and, locally, overabundant pigeon species (Columba palumbus) as an effective disperser of domestic olive trees (Olea europaea), a widespread cultivated tree, considered a naturalized and invasive species in many areas of the world. By analyzing crop and gizzard content we found that olive fruits were an important food item for pigeons in late winter and spring. A proportion of 40.3% pigeons consumed olive seeds, with an average consumption of 7.8 seeds per pigeon and day. Additionally, most seed sizes (up to 0.7 g) passed undamaged through the gut and were dispersed from cultivated olive orchards to areas covered by protected Mediterranean vegetation, recording minimal dispersal distances of 1.8–7.4 km. Greenhouse experiments showed that seeds dispersed by pigeons significantly favored the germination and establishment in comparison to non-ingested seeds. The ability of pigeons to effectively disperse domestic olive seeds may facilitate the introduction of cultivated olive trees into natural systems, including highly-protected wild olive woodlands. We recommend harvesting ornamental olive trees to reduce both pigeon overpopulation and the spread of artificially selected trees into the natural environment.