Quantitative differences detected in the histology of galls induced by the same aphid species in different varieties of the same host.

Plant galls are abnormal growths caused by an inducer that determines their morphology and anatomy. We qualitatively and quantitatively compared the histological anatomy of five aphid species (Paracletus cimiciformis, Forda marginata, Forda formicaria, Baizongia pistaciae and Geoica wertheimae) that induce galls in Pistacia terebinthus shrubs growing in Israel. We also quantitatively compared these galls to those that the aphids create on the same host in Spain. Histological study was conducted following methods described previously by the authors. Quantitative differences among the galls were found in five of 12 common anatomical traits: gall thickness, stomatal number in the epidermis-air, size of vascular bundles, distance of phloem ducts from the lumen and number of intraphloematic schizogenous ducts. Other structures were particular to one or some species: number of cracks in the epidermis-lumen, a sclereid layer, trichomes and microcrystal inclusions. Fisher's tests of combined probabilities showed that the galls induced in Israel were statistically different from those in Spain. In particular, the number of intraphloematic schizogenous ducts was higher in the galls induced in P. terebinthus in Israel. Such differences were also found in other traits related to defence of the gall inhabitant. In conclusion, while the gall shape and size are determined mainly by the cecidogenic insect, it seems that the host plant also plays an important role in determining the number/size of quantitative traits, in this case mainly protective structures.

Contribution of gall microscopic structure to taxonomy of gallicolous aphids on Pistacia.

Aphids inducing galls on Pistacia plants belong to the tribe Fordini. According to the Heie & Wegierek classification, the genera are grouped into three subtribes. Previous microscopic studies showed that this taxonomy is not consistent with the histological characteristics of the galls. In this paper, galls induced by Aplonerura lentisci, Asiphonella cynodonti, Forda riccobonii, Slavun wertheimae and Smynthurodes betae were analyzed for the first time, as well as nine other galls previously described. Based on histological features three groups of galls can be establish: the first group comprises closed galls, induced by Baizongia pistaciae, Geoica utricularia, Rectinasus buxtoni and Slavun wertheimae; the second group includes two species of Geopemphigus (G. blackmani and G. torsus), and the third one is divided into two subgroups, the first comprises Aplonerura lentisci, Asiphonella cynodonti and Geopemphigus morral, and the second that includes Forda formicaria, F. marginata, F. riccobonii, Paracletus cimiciformis and Smynthurodes betae. An identification key of species based on microscopic features of galls is presented.

Morphological leaf variability in natural populations of Pistacia atlantica Desf. subsp. atlantica along climatic gradient: new features to update Pistacia atlantica subsp. atlantica key.

The effect of bioclimate range on the variation in Pistacia atlantica Desf. subsp. atlantica leaf morphology was studied on 16 sites in Northwest Algeria. The study examined biometrically mature leaves totaling 3520 compound leaves. Fifteen characters (10 quantitative and 5 qualitative) were assessed on each leaf. For each quantitative character, the nested analysis of variance (ANOVA) was used to examine relative magnitude of variation at each level of the nested hierarchy. The correlation between the climatic parameters and the leaf morphology was examined. The statistical analysis applied on the quantitative leaf characters showed highly significant variation at the within-site level and between-site variation. The correlation coefficient (r) showed also an important correlation between climatic parameters and leaf morphology. The results of this study exhibited several values reported for the first time on the species, such as the length and the width of the leaf (reaching up to 24.5 cm/21.9 cm), the number of leaflets (up to 18 leaflets/leaf), and the petiole length of the terminal leaflet (reaching up to 3.4 cm). The original findings of this study are used to update the P. atlantica subsp. atlantica identification key.

The histo structure of galls induced by aphids as a useful taxonomic character: the case of Rectinasus (Hemiptera, Aphididae, Eriosomatinae).

Morphological differentiation of gall tissues induced on plants may play a role to characterize the real taxonomic position of the gall inducer. We verified this hypothesis with galls induced by Rectinasus buxtoni on Pistacia palaestina. There is controversy about the taxonomic localization of genus Rectinasus: in one classification it is situated with the genera Forda and Paracletus while in another it is linked to the genera Geoica and Baizongia. Histological examination of the walls of the galls reveals the presence of two opposed vascular bundles and an inner surface of the gall with cavities. These features place Rectinasus in the same group as Geoica and Baizongia, and not with Paracletus and Forda, whose galls have a different histological structure, as generally admitted.

Hydraulic lift and tolerance to salinity of semiarid species: consequences for species interactions.

The different abilities of plant species to use ephemeral or permanent water sources strongly affect physiological performance and species coexistence in water-limited ecosystems. In addition to withstanding drought, plants in coastal habitats often have to withstand highly saline soils, an additional ecological stress. Here we tested whether observed competitive abilities and C-water relations of two interacting shrub species from an arid coastal system were more related to differences in root architecture or salinity tolerance. We explored water sources of interacting Juniperus phoenicea Guss. and Pistacia lentiscus L. plants by conducting physiology measurements, including water relations, CO2 exchange, photochemical efficiency, sap osmolality, and water and C isotopes. We also conducted parallel soil analyses that included electrical conductivity, humidity, and water isotopes. During drought, Pistacia shrubs relied primarily on permanent salty groundwater, while isolated Juniperus plants took up the scarce and relatively fresh water stored in upper soil layers. As drought progressed further, the physiological activity of Juniperus plants nearly stopped while Pistacia plants were only slightly affected. Juniperus plants growing with Pistacia had stem-water isotopes that matched Pistacia, unlike values for isolated Juniperus plants. This result suggests that Pistacia shrubs supplied water to nearby Juniperus plants through hydraulic lift. This lifted water, however, did not appear to benefit Juniperus plants, as their physiological performance with co-occurring Pistacia plants was poor, including lower water potentials and rates of photosynthesis than isolated plants. Juniperus was more salt sensitive than Pistacia, which withstood salinity levels similar to that of groundwater. Overall, the different abilities of the two species to use salty water appear to drive the outcome of their interaction, resulting in asymmetric competition where Juniperus is negatively affected by Pistacia. Salt also seems to mediate the interaction between the two species, negating the potential positive effects of an additional water source via hydraulic lift.

Abscission of pistachio flowers and fruits as affected by different pollinators.

This study was conducted in Ceylanpinar State Farm to determine influence of pollens of 9 different pollinators on the flower and fruit abscission of the pistachio. Comparison of pollinator effect on the abscission of flowers and fruits of 3 pistachio cultivars showed that pollens of Pistacia vera L. may increase or reduce flower and fruit abscission. Flower and fruit abscission occurred primarily during the flowering and small-fruit period, that the June and pre-harvest abscissions were low. Data collected for 3 consecutive years revealed that 83.4 to 88.2% of the flowers and fruits of Kirmizi pistachio cultivar abscised mainly during an initial 50 days after Full Blooming (FB). Siirt cultivar abscised during an initial 35 days after FB with a rate of 82.1 to 90.9%. Abscission rate of Ohadi cultivar were 84.5 to 88.6% that occurred during an initial 50 days after FB period. Males noted as 12 and 13 resulted the highest abscission in Siirt cultivar. Results demonstrated that pollinators affect flower and fruit abscission in pistachio.

Morpho-anatomical, physiological and biochemical adjustments in response to root zone salinity stress and high solar radiation in two Mediterranean evergreen shrubs, Myrtus communis and Pistacia lentiscus.

Salt- and light-induced changes in morpho-anatomical, physiological and biochemical traits were analysed in Myrtus communis and Pistacia lentiscus with a view to explaining their ecological distribution in the Mediterranean basin. In plants exposed to 20 or 100% solar radiation and supplied with 0 or 200 mm NaCl, measurements were conducted for ionic and water relations and photosynthetic performance, leaf morpho-anatomical and optical properties and tissue-specific accumulation of tannins and flavonoids. Net carbon gain and photosystem II (PSII) efficiency decreased less in P. lentiscus than in M. communis when exposed to salinity stress, the former having a superior ability to use Na(+) and Cl(-) for osmotic adjustment. Morpho-anatomical traits also allowed P. lentiscus to protect sensitive targets in the leaf from the combined action of salinity stress and high solar radiation to a greater degree than M. communis. Salt and light-induced increases in carbon allocated to polyphenols, particularly to flavonoids, were greater in M. communis than in P. lentiscus, and appeared to be related to leaf oxidative damage. Our data may conclusively explain the negligible distribution of M. communis in open Mediterranean areas suffering from salinity stress, and suggest a key antioxidant function of flavonoids in response to different stressful conditions.

Effects of ozone on the foliar histology of the mastic plant (Pistacia lentiscus L.).

An open-top chamber study was conducted to investigate the tissue and cellular-level foliar effects of ozone (O3) on a Mediterranean evergreen species, the mastic plant (Pistacia lentiscus L.). Plants were exposed at three different O3 levels, and leaf samples were collected periodically from the beginning of the exposure. Although no visible foliar injury was evident, alterations of the plastids and vacuoles in the mesophyll were observed. Senescence processes were accelerated with an anomalous stacking of tannin vacuoles, and a reduction in the size and number of the chloroplasts. Overall, most of the modifications induced by O3 were consistent with previously reported observations on deciduous broadleaf species, with the exception of alterations in the cells covering the secretory channels, reported here as a new finding. Comments on the feasibility of using microscopy to validate O3 related field observations and subtle foliar injury are also given.