Comparison of the chemical composition and the organoleptic profile of virgin olive oil from two wild and two cultivated Tunisian Olea europaea

With the aim to select new olive cultivars with superior physical and chemical properties than the cultivar Chemlali Sfax, the present study focused on the comparison of the chemical composition and the sensory profile of the virgin olive oils (VOOs) of two wild olive trees (Oleasters K and M) with those of VOOs obtained from Chemlali Sfax and Neb Jmel olive cultivars, all growing in the coastal region of Tunisia. Despite the variability in the chemical composition (fatty acids, pigments, and phenolic and volatile compounds) and the organoleptic profile of the VOOs of the oleasters and the cultivars, the quality indices (free fatty acids, peroxide value, and spectrophotometric indices K232 and K270) as well as the fatty acid composition of all VOOs studied met the commercial standards. Both the α-tocopherol and phenol contents varied between the genotypes. The Neb Jmel and Oleaster K VOOs had more than two times higher total phenol levels than the Chemlali Sfax and Oleaster M VOOs. Also the contents of volatile compounds differed between the olive oils studied. Chemlali Sfax and Oleaster K oils were more abundant in aldehydes, whereas Oleaster M VOO had higher contents of alcohols. These results were confirmed by a sensorial analysis showing that the later oil was deprived for consumption despite its abundance in α-tocopherol. In conclusion, the oleasters studied revealed to be interesting, since they produced oils with good quality characteristics in terms of minor compounds (phenols and volatiles) compared to the Chemlali Sfax cultivar.     

Influence of canopy fruit location on morphological,histochemical and biochemical changes in two oil olive cultivars

The influence of different irradiance conditions was evaluated under natural solar radiation by comparing well-exposed (in) and shaded fruit (out) in canopies of olive trees (Olea europaea L). Over a 2-year period, from 50 days after full bloom up to harvest time, “in” and “out” olive samples of two genotypes (“Frantoio Millennio” and “Coratina 5/19”) were periodically collected. Morphological, histochemical, and biochemical analysis were performed to study the changes on fruit morphometric traits, oil body accumulation, and β-glucosidase enzyme activity. Some parameters were modified by shading inside the canopy in which the proportion of incident photosynthetically active radiation intercepted by the crop was 47%. Shaded fruits developed at slow rate and were characterized by late darkgoing time, reduced size, with a tendency toward oblong shape. The rapid histochemical procedure proposed to estimate the oil body accumulation during fruit ripening showed that a reduced irradiance caused a decrease in oil body density. The canopy position influenced, in a different way, the β-glucosidase activity in relation to the fruit-ripening stage in both genotypes. These findings indicate that providing an adequate and uniform lighting of the olive canopy by careful choices of orchard management practices can be a key factor for several yield components.     

Organic carbon fluxes by precipitation,throughfall and stemflow in an olive orchard in Southern Spain

In forests and grasslands, canopy-derived carbon fluxes have been shown to be an important part of the carbon cycle, yet very few data are available for permanent agricultural crops. Concentration of total (TOC), dissolved (DOC) and particulate organic carbon (POC) was measured during an entire hydrological year in direct rainfall throughfall and stemflow in a mature olive orchard. Throughfall accounted for 68% of incoming rainfall, but TOC concentration was on average 14 times higher than in rainfall (7.63 vs. 106.12 mg/L). Stemflow on the other hand represented only a small fraction of gross precipitation, on average less than 1%, while its TOC concentration was on average 10-fold higher than in rainfall (74.13 mg/L). Dynamics of OC enrichment were mainly driven by precipitation patterns, as well as plant phenology, whereas a dramatic increase happened during flowering. Stemflow and throughfall were proven to be important sources of organic carbon supplying 13.5 g C/m²/year beneath the canopy of each tree, while 2.41 g C/m²/year reached the soil through gross precipitation. This large fraction of carbon is a mean of recirculating important carbon compounds that may help mobilize soil nutrients and maintain water holding capacity in the circumscribed area below olive canopies.     

Primary domestication and early uses of the emblematic olive tree: palaeobotanical, historical and molecular evidence from the Middle East

Our knowledge of the origins of olive tree domestication in the Middle East and on the processes governing its extension and persistence in different vegetation types from prehistory through antiquity to modern times derives from diverse sources, spanning the biological sciences to the humanities. Nonetheless, it lacks a robust overview that may lead to floating interpretations. This is especially true in the Middle East, considered as the cradle of agriculture, and where the evolutionary history of this emblematic tree is intertwined with that of civilizations. Olive fruit, oil and wood have been, since Prehistoric times, characteristic products of the lands bordering the Mediterranean Sea. In the domestic economy of these countries, the olive tree gradually became a traditional tree crop since the first oil extraction, through the emergence of regional commerce that accompanied the rise and fall of early Near-Middle Eastern urbanism, until the development of modern trade, with an oil production estimated at circa 3000000 tons per year. The rising importance of the olive tree in human life has turned the tree into an endless source of fascination in the Aegean and Eastern Mediterranean, a symbol and a sacred tree, widely cited in the Bibles, the Koran, and in ancient literature. Here we argue that advances in radiocarbon chronology, palaeobotany, genetics, and archaeology-history have profoundly refined the history of olive trees in the Middle East. This review shows that the heartland of primary olive domestication must be enlarged to the Levant and not only focus on the Jordan Valley. The domestication of the olive tree is a long and ongoing process, linked to the early production of oil and the development of the olive trade. We also suggest that the olive tree became a particular icon, a sacred tree, during the Biblical period in the Levant.     

Ultrastructural aspects of the cytoplasmic origin and accumulation of oil in olive fruit (Olea europaea)

The development of oil bodies and oil droplets in fruits of olive was examined at the ultrastructural level. Both oil bodies that form in young fruits and oil droplets that develop with fruit maturation are cytoplasmic bodies. The formation of the small oil bodies occurs in localized regions of the cytoplasm. These bodies are closely associated and fuse together, forming a small oil droplet that protruded against and indented the vacuolar membrane. As the fruit matures, new oil bodies appear to form and fuse with the oil droplet, resulting in the formation of a single large oil droplet of about 30 μm in diameter in most mature mesocarp cells. The cytoplasmic region where the oil bodies formed had a granulate, ultrastructural appearance, and cytoplasmic components such as membranes and ribosomes were noticeably absent in these regions. The granulate material coated the oil bodies and oil droplets, and appeared as a thin, compressed band between the round inner surface of the droplets and the indented tonoplast. We suggest that this granulate material is involved in the synthesis of the oil and, with enlargement of the oil bodies, this coat becomes thinner in regions where they are closely associated, resulting in zones where confluence of the oil occurs.     

Historical biogeography of olive domestication (Olea europaea L.) as revealed by geometrical morphometry applied to biological and archaeological material

Aim This study intends to improve our understanding of historical biogeography of olive domestication in the Mediterranean Basin, particularly in the north-western area. Location Investigations were performed simultaneously on olive stones from extant wild populations, extant cultivated varieties from various Mediterranean countries, and archaeological assemblages of Spanish, French and Italian settlements. Methods A combination of morphometrics (traditional and geometrical) allowed us to study both the size and shape of endocarp structure. Concerning shape, a size-standardized method coupled with fitted polynomial regression analysis was performed. Results We found morphological criteria for discriminating between wild and cultivated olive cultivars, and established patterns of morphological variation of olive material according to the geographical origin (for extant material) and to the age of the olive forms (for archaeological material). Levels of morphological convergences and divergences between wild olive populations and cultivated varieties are presented as evidence. Main conclusions Morphological changes of endocarps of olive under domestication at both geographical and chronological scales provide new criteria for the identification of olive cultivars. They allow to determine the origins of cultivated forms created and/or introduced in the north-western Mediterranean regions and to understand how human migrations affected the rest of the Western Mediterranean regions. A model of diffusion of olive cultivation is proposed. It shows evidence of an indigenous origin of the domestication process, which is currently recognized in the north-western area since the Bronze Age.     

Contribution of the adaxial and abaxial surfaces of olive leaves to photosynthesis

Leaves of olive cultivars Frantoio and Maurino were irradiated with different irradiances from above, from below, or simultaneously from both directions to determine the contribution of the abaxial and adaxial leaf surfaces to photosynthesis. In both cultivars, irradiation of both sides of the leaf caused increases in net photosynthetic rate (P _N) and apparent quantum yield compared to irradiating only one surface with the equal photosynthetic photon flux density (PPFD), but the PPFD needed to saturate P _N decreased. At high and medium PPFD the P _N determined at irradiating both leaf surfaces was less than the sum obtained at irradiation of only the upper or the lower surface with the same PPFD. At PPFD higher than 1000 μmol m-2 s-1 in cv. Frantoio and 1200 μmol m-2 s-1 in cv. Maurino, P _N did not vary. At low PPFD (<200 μmol m-2 s-1), P _N at irradiating the adaxial and abaxial leaf surfaces simultaneously was about the sum of the values obtained by irradiating the upper and lower surfaces separately. Consequently the compensation irradiance was reduced from about 50 μmol m-2 s-1 to about 30 μmol m-2 s-1 when irradiating both leaf surfaces. The natural leaf orientation of the olive cultivar influenced the utilization of radiant energy by the abaxial surface. This revised version was published online in September 2006 with corrections to the Cover Date.     

欧橄榄叶中的新裂环烯醚萜

从欧橄榄(Olea europaeaL.)干燥叶的乙酸乙酯部位分离得到5个裂环烯醚萜类化合物。通过波谱分析和理化常数对照等方法,上述化合物分别鉴定为6′-O-甲基橄榄苦苷(6′-O-methyloleuropein,1)、橄榄苦苷(oleu-ropein,2)、(1S)-methylelenolate(3)、3,4-二羟基苯乙基-4-甲酰基-3-甲酰甲基-4-己烯酯(4)和oleoside(5)。其中化合物1为新化合物。     

Genetic and landscape characterization of ancient autochthonous olive trees in northern Italy

Several ancient olive plants with different genetic, agronomic and morphological characteristics are widespread in the Emilia-Romagna region. In this study, details of 206 trees located in four provinces were collected and their phytometric traits were recorded. Easily recognizable varieties were identified, while plants of uncertain genetic identity were submitted for molecular analysis with SSR markers and compared with cultivars widespread in central Italy and Emilia-Romagna. The genetic analyses showed that most of the ancient olive trees belonged to 10 cultivars that are already characterized, with different cases of intra-varietal clones. The remaining accessions belonged to 19 different genotypes of unknown origin. The highest percentage of policormic trees was found in the Bologna and Rimini provinces. A high percentage of plants located under unfavourable aspects (west to east) was found only in the Rimini territory, which presents peculiar and milder climatic conditions compared to the other provinces. Slope appeared not to be a limiting factor for tree survival. The information obtained could help the rational reintroduction of olive growing in suitable areas of Emilia-Romagna, with the subsequent economic advantages, erosion preservation and germplasm enrichment.     

A typology of sloping and mountainous olive plantation systems to address natural resources management

Olive plantation systems occur in a wide variety throughout the Mediterranean, especially in sloping and mountainous areas. Recent drivers of change, including the widespread introduction of mechanisation, increased use of (chemical) inputs and (drip)irrigation have considerably added to this diversity. The various systems have very different resource use patterns and environmental and social performances. This article attempts to grasp these differences and to link systems characteristics to options for natural resources management in the spirit of contemporary agricultural policies that seek to promote a more sustainable agriculture. Cluster analysis was employed to classify 28 olive plantation systems distinguished by regional typologies developed for six study areas: Trás‐os‐Montes (Portugal), Córdoba and Granada/Jaén (both in Spain), Haffouz (Tunisia), Basilicata/Salerno (Italy) and West‐Crete (Greece). Six types of olive plantation systems resulted: (a) very extensive, (b) traditional extensive, (c) semi‐intensive low input, (d) semi‐intensive high input, (b) intensive and (e) organic. Natural resources management options to address soil erosion, low biodiversity, wildfire risk and excessive water use are explored for each of these systems. In the discussion, it becomes evident that an important quality for a typology lies in its capacity to differentiate likely future development pathways. If options are known, policy‐makers can make choices as to what the desired pathway is and what instruments to design to facilitate it.     

Effects of untreated two‐phase olive mill pomace on potted olive plantlets

Two‐phase pomace represents an important environmental problem in Mediterranean areas. With its high organic content, direct application of two‐phase pomace in the field is recommended to improve soil organic carbon levels and fertility. However, this does not consider any antagonistic effects that this application might have on root proliferation and biomass partitioning. We studied the effects of untreated two‐phase pomace on properties of growth substrate, and on shoot and root growth and biomass allocation of potted olive plantlets. A pot experiment was carried out in a greenhouse over 90 days, with five levels of two‐phase pomace and using two olive cultivars. The effects on shoot growth, leaf pigment content and maximum quantum efficiency of photosystem II (ΦPSII) were assessed each month. After 90 days, the shoot and root biomass of the olive plants was quantified, along with total organic matter, and carbon, nitrogen and polyphenol contents of the growth substrate and shoots, and the fine root nutritional status. Two‐phase pomace increased the total organic matter, total nitrogen and polyphenol contents of the growth substrate. It significantly altered biomass partitioning in the olive plantlets, with reduced shoot dry mass and leaf area, and new shoot formation. It also increased fine and total root dry mass for all two‐phase pomace levels except 40%. There were no significant differences in leaf pigment content and ΦPSII across the treatment levels. Therefore, application of untreated two‐phase pomace at more than 4% induces a severe imbalance in olive plantlet biomass partitioning, and shoot and root growth.     

Abnormalities induced by agricultural pesticides in the microsporogenesis of olive tree (Olea europaea L.) cultivars

The study evaluated the microsporogenesis of olive trees subjected to different agricultural pesticide applications during flowering. Inflorescences of cultivars Arbequina and MGS GRAP541 were subjected to agricultural pesticides: mineral oil, neem oil, dimethoate and deltamethrin. The floral buds were fixed in Carnoy for the microsporogenesis analysis and in Karnovsky for scanning electron microscopy. The slides were prepared by squash technique and staining with propionic carmine. The pollen viability was determined by Alexander’s stain and in vitro germination. Results show that the quantification of abnormalities in meiosis in the two cultivars caused significant effect among the treatments, being that all differed statistically from the control group. Both methods showed a higher percentage of viable pollens in the control treatment and lower percentage of viability with the agricultural pesticides. The method of pollen viability by staining presented the highest averages of viable pollens, but when compared together, both methods presented a strongly related positive linear correlation. It was concluded that the used chemical products increased the percentage of chromosomal abnormalities during microsporogenesis, which interfered in the pollen viability of the two analyzed cultivars. The product deltamethrin caused the strongest effect on meiosis and on pollen viability.     

Paternity tests support a diallelic self‐incompatibility system in a wild olive (Olea europaea subsp. laperrinei,Oleaceae)

Self‐incompatibility (SI) is the main mechanism that favors outcrossing in plants. By limiting compatible matings, SI interferes in fruit production and breeding of new cultivars. In the Oleeae tribe (Oleaceae), an unusual diallelic SI system (DSI) has been proposed for three distantly related species including the olive (Olea europaea), but empirical evidence has remained controversial for this latter. The olive domestication is a complex process with multiple origins. As a consequence, the mixing of S‐alleles from two distinct taxa, the possible artificial selection of self‐compatible mutants and the large phenological variation of blooming may constitute obstacles for deciphering SI in olive. Here, we investigate cross‐genotype compatibilities in the Saharan wild olive (O. e. subsp. laperrinei). As this taxon was geographically isolated for thousands of years, SI should not be affected by human selection. A population of 37 mature individuals maintained in a collection was investigated. Several embryos per mother were genotyped with microsatellites in order to identify compatible fathers that contributed to fertilization. While the pollination was limited by distance inside the collection, our results strongly support the DSI hypothesis, and all individuals were assigned to two incompatibility groups (G1 and G2). No self‐fertilization was observed in our conditions. In contrast, crosses between full or half siblings were frequent (ca. 45%), which is likely due to a nonrandom assortment of related trees in the collection. Finally, implications of our results for orchard management and the conservation of olive genetic resources are discussed.     

Dormancy and germination of olive embryos as affected by temperature

Olive seeds do not germinate promptly when placed under favourable conditions, which is a problem in raising young plants for breeding or experimental purposes. In a series of experiments an investigation of the role of temperature in the germination of olive embryos was conducted. Naked, unchilled olive embryos ( Olea europaea L. cv. Chalkidikis), cultured in vitro at 20°C, had a germination capacity of 73%, whereas that of embryos which had previously been chilled at 10°C for 2 or more weeks reached 96%. Intact seeds did not germinate at 20°C unless they had previously been subjected to 10°C for 3 or 4 weeks. Embryos chilled while in the intact seed and excised just before transfer to 20°C, reacted in a similar way to naked embryos, but reached their maximum germination capacity after 4 weeks at 10°C. Under constant temperature conditions the highest germination percentage of embryos was observed at 10 and 15°C and the highest germination rate at 15°C, while a moderate capacity and rate of germination occurred at 20°C, and a very low percentage and rate at 25 and 30°C. Prechilling at 10°C did not affect germination at 15°C, but improved the percentage and the rate of germination at 20, 25 and 30°C. The germination percentages of embryos chilled for 1 or 2 weeks at 10°C and then transferred to 25°C were lower than those of similarly chilled embryos transferred to 20°C. The chilling effect could not be reversed at 25°C when the embryos had been chilled for 3 or more weeks. The results show that olive seeds exhibit a state of dormancy that is caused by factors residing partly in the endosperm and partly within the embryo.     

Heat shock response in olive (Olea europaea L.) twigs: Identification and analysis of a cDNA coding a class I small heat shock protein

Abstract

The objective of this study was to investigate at the molecular level the heat shock response in olive by identifying sequences coding for heat shock proteins (HSPs). Young twigs of Olea europaea trees (cv Cellina di Nardò) were subjected to different temperature treatments in order to induce the expression of heat shock genes. In order to identify genes induced by heat treatment, we used a PCR-based approach to amplify specific HS cDNAs. Search for low molecular weight HSP sequences was performed in public domain databases in order to design specific primers based upon multisequence alignments. By this approach, we isolated the first full length cDNA encoding a low-molecular weight HSP from O. europaea. This is a class I low molecular weight HSP of 18.3 kDa, which is highly expressed in young twigs subjected to heat stress.     

Isolation and characterization of polymorphic microsatellites in olive (Olea europaea L.) and their transferability to other genera in the Oleaceae

Seven polymorphic microsatellites were developed in olive. Six of them came from a genomic library enriched for GA and CA repeat sequences. They showed single locus polymorphism in a set of 23 olive cultivars (from six to nine alleles per locus). Three different pairs of loci were sufficient to discriminate all cultivars. The other polymorphic primer pair was designed from a published sequence for olive lupeol sgutase and revealed just two alleles. The seven primer pairs were tested on two accessions of five other species of the Oleaceae and three, EMO2, EMO13 and EMO90, revealed polymorphism in two, four and three species, respectively.     

油橄榄品种间叶片性状及总黄酮含量分析

为了解油橄榄(Olea europaea L.)叶片性状和总黄酮含量在品种间的差异,对四川省青川县栽培的10个油橄榄品种的叶片性状和总黄酮含量进行测量。结果表明,叶片性状在品种间的差异均达到显著水平,且性状间存在显著或极显著相关性。‘钟山24号’的叶面积最大,‘皮削利’的最小。叶片性状中以周长的变异系数最大,叶面积的最小。‘鄂植8号’的叶面积、‘莱星’的叶宽、‘小苹果’叶长宽比、‘埃蒙’的叶形的变异系数最大,而‘皮削利’的叶片性状相对稳定。6个叶片性状可以简化成形状系数和叶长作为主要代表性状。叶片总黄酮含量为0.07~3.39 mg g~(-1),品种间存在显著差异,春梢含量总体高于秋梢;‘皮削利’、‘豆果’、‘钟山24号’和‘卡林’的春秋梢叶片含量差异较大,‘佛奥’的最小;‘鄂植8号’和‘科拉蒂’春秋梢叶片的总黄酮含量较高,‘皮削利’的秋梢好于春梢;‘卡林’的春梢叶片的总黄酮含量最少,为3.02 mg g~(-1),秋梢中‘豆果’的最低,为2.64 mg g~(-1);‘科拉蒂’、‘钟山24号’、‘埃蒙’和‘鄂植8号’的总黄酮含量与叶片性状存在显著或极显著的正相关或负相关。这说明总黄酮含量在一定程度上受到叶片生长的影响。     

Chloroplast-DNA variation in cultivated and wild olive (Olea europaea L.)

Polymorphism in the lengths of restriction fragments of the whole cpDNA molecule was studied in cultivated olive and in oleaster (wild olive) over the whole Mediterranean Basin. Seventy two olive cultivars, 89 very old trees cultivated locally, and 101 oleasters were scored for ten endonucleases. Moreover, maternal inheritance of cpDNA in olive was shown by analysing the progeny of a controlled cross between two parents which differed in their cpDNA haplotypes. In the whole species, three site- and three length-mutations were observed, corresponding to five distinct chlorotypes. The same chlorotype (I) was predominant in both oleasters and cultivated olive trees, confirming that these are closely related maternally. Three other chlorotypes (II, III and IV) were observed exclusively in oleaster material and were restricted either to isolated forest populations or to a few individuals growing in mixture with olive trees possessing the majority chlorotype. An additional chlorotype (V) was characterised by three mutations located in distinct parts the cpDNA molecule but which were never observed to occur separately. This chlorotype, more widely distributed than the other three, in both cultivated and wild olive, and occurring even in distant populations, was observed exclusively in male-sterile trees showing the same specific pollen anomaly. However, in the present study, no evidence was provided for a direct relationship between the occurrence of the cpDNA mutations and male sterility. It is suggested that the large geographic distribution of chlorotype V may be related to the high fruit production usually observed on male-sterile trees. These may be very attractive for birds which are fond of olive fruit and spread the stones efficiently. Probably for the same reason, people preserved male-sterile oleasters for long periods and, in several places, used male-sterile cultivars over large areas. Received: 25 November 1998 / Accepted: 19 December 1998