Daily consumption of wild olive (acebuche) oil reduces blood pressure and ameliorates endothelial dysfunction and vascular remodelling in rats with L-NAME-induced hypertension

Purpose: Despite numerous reports on the beneficial effects of olive oil in the cardiovascular context, very little is known about the olive tree’s wild counterpart (Olea europaea, L. var. sylvestris), commonly known as acebuche (ACE) in Spain. The aim of this study was to analyse the possible beneficial effects of an extra virgin ACE oil on vascular function in a rodent model of arterial hypertension induced by L-NAME (NG-nitro-L-arginine methyl ester). Methods: Four experimental groups of male Wistar rats were studied: 1) normotensive rats (Control group); 2) normotensive rats fed a commercial diet supplemented with 15% (w/w) ACE oil (Acebuche group); 3) rats made hypertensive following administration of L-NAME (L-NAME group); and 4) rats treated with L-NAME and simultaneously supplemented with 15% ACE oil (LN+ACE group). All treatments were maintained for 12 weeks. Results: Besides a significant blood pressure-lowering effect, the ACE oil-enriched diet counteracted the alterations found in aortas from hypertensive rats in terms of morphology and responsiveness to vasoactive mediators. In addition, a decrease in hypertension-related fibrotic and oxidative stress processes was observed in L-NAME-treated rats subjected to ACE oil supplement. Conclusion: Using a model of arterial hypertension via nitric oxide depletion, here we demonstrate the beneficial effects of a wild olive oil based upon its vasodilator, antihypertensive, antioxidant, antihypertrophic and antifibrotic properties. We postulate that regular inclusion of ACE oil in the diet can alleviate the vascular remodelling and endothelial dysfunction processes typically found in arterial hypertension, thus resulting in a significant reduction of blood pressure.

Shape Diversity of Olive Stone, Resulting from Domestication and Diversification, Unveils Traits of the Oldest Known, 7000-Years-Old Table Olives from Hishuley Carmel Site (Israel)

The first exploited and domesticated olive forms are still unknown. The exceptionally well-preserved stones from the submerged Hishuley Carmel site (Israel), dating from the middle of the 7th millennium BP, offer us the opportunity to study the oldest table olives discovered so far. We apply a geometrical morphometric analysis in reference to a collection of modern stones from supposed wild populations and traditional varieties of various origins, genetic lineages and uses. Analyses carried out on modern material allow to characterize the extent of stone morphological variation in the olive tree and differentiate distinct morphotypes. They also allow to discuss the status of supposed wild populations and interpret the divergence between groups of varieties and their wild progenitors in an evolutionary and biogeographical perspective. Shape of archaeological stones compared to the differentiation model, unveils morphological traits of olives most likely belonging to both wild olive trees and domesticated forms, some of them showing a notable domestication syndrome. This forms at the early stages of domestications, some of which surprisingly morphologically close to modern varieties, were probably used for dual use (production of olive oil and table olives), and possibly contributed to the dispersion of the olive tree throughout the Mediterranean Basin and to its subsequent diversification.

Physiological and Biochemical Response of Wild Olive (Olea europaea Subsp. europaea var. sylvestris) to Salinity

In the face of climate change, water deficit and increasing soil salinity pose an even greater challenge to olive cultivation in the Mediterranean basin. Due to its tolerance to abiotic stresses, wild olive (Olea europaea subsp. europaea var. sylvestris) presents a good candidate in breeding climate-resilient olive varieties. In this study, the early response of the native Croatian wild olive genotype (WOG) to salinity was evaluated and compared with that of well-known cultivars (cv.) Leccino and Koroneiki. Potted olive plants were exposed either to 150 mM NaCl or 300 mM mannitol for 3 weeks to distinguish between the osmotic and ionic components of salt stress. To determine the impact of the plant age on salinity, 1-, 2-, and 3-year-old WOG plants were used in the study. The growth parameters of both the cultivars and WOG of different ages decreased in response to the mannitol treatment. In contrast to cv. Leccino, the NaCl treatment did not significantly affect the growth of cv. Koroneiki or WOG of any age. The contents of Na+ and Cl− were considerably higher in the salt-treated WOG, regardless of age, compared with the cultivars. However, while both treatments significantly reduced the K+ content of cv. Koroneiki, that nutrient was not significantly affected in either cv. Leccino or WOG. Unlike the cultivars and older WOG, the NaCl treatment caused a significant decline of photosynthetic pigments in the 1-year-old WOG. The cultivars and WOG of different ages experienced a similar drop in the chlorophyll a content under the isotonic mannitol treatment. The absence of lipid peroxidation, modulation of superoxide dismutase, and guaiacol peroxidase activity were noted in all WOG ages under both stressors. These data suggest that WOG resilience to salinity is associated with its large leaf capacity for Na+ and Cl− accumulation, K+ retention, and its adaptable antioxidative mechanisms. The results are promising with regard to obtaining a new olive cultivar with better resilience to soil salinity.

Anti-Inflammatory Action of Dietary Wild Olive (Acebuche) Oil in the Retina of Hypertensive Mice

Inflammation plays a crucial role in the course of eye diseases, including many vascular retinopathies. Although olive oil is known to have beneficial effects against inflammatory processes, there is no information available on the anti-inflammatory potential of the wild olive tree (namely, acebuche (ACE) for the primitive Spanish lineages). Here we investigate the anti-inflammatory effects of ACE oil in the retina of a mouse model of arterial hypertension, which was experimentally induced by administration of L-NAME (NG-nitro-L-arginine-methyl-ester). The animals were fed supplements of ACE oil or extra virgin olive oil (EVOO, for comparative purposes). Retinal function was assessed by electroretinography (ERG), and different inflammation-related parameters were measured in the retina and choroid. Besides significant prevention of retinal dysfunction shown in ERG recordings, ACE oil-enriched diet upregulated the expression of the anti-inflammatory markers PPARγ, PPARα and IL-10, while reducing that of major proinflammatory biomarkers, IL-1β, IL-6, TNF-α and COX-2. This is the first report to highlight the anti-inflammatory properties of an ACE oil-enriched diet against hypertension-related retinal damage. Noteworthy, dietary supplementation with ACE oil yielded better results compared to a reference EVOO.

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

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

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

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