In olive trees, Xylella fastidiosa colonizes xylem vessels and compromises water transport causing the olive quick decline syndrome (OQDS). The loss of hydraulic conductivity could be attributed to vessel occlusions induced both by the bacteria biofilm and by plant responses (tyloses, gums, etc.) that could trigger embolism. The ability of the infected plants to detect embolism and to respond, by activating mechanisms to restore the hydraulic conductivity, can influence the severity of the disease symptomatology. In order to investigate these mechanisms in the X . fastidiosa -resistant olive cultivar Leccino and in the susceptible Cellina di Nardò, sections of healthy olive stems were analysed by laser scanning microscope to calculate the cavitation vulnerability index. Findings indicated that the cultivar Leccino seems to be constitutively less susceptible to cavitation than the susceptible one. Among the vascular refilling mechanisms, starch hydrolysis is a well-known strategy to refill xylem vessels that suffered cavitation and it is characterized by a dense accumulation of starch grains in the xylem parenchima; SEM-EDX analysis of stem cross-sections of infected plants revealed an aggregation of starch grains in the Leccino xylem vessels. These observations could indicate that this cultivar, as well as being anatomically less susceptible to cavitation, it also could be able to activate more efficient refilling mechanisms, restoring vessel’s hydraulic conductivity. In order to verify this hypothesis, we analysed the expression levels of some genes belonging to families involved in embolism sensing and refilling mechanisms: aquaporins, sucrose transporters, carbohydrate metabolism and enzymes related to starch breakdown, alpha and beta-amylase. The obtained genes expression patterns suggested that the infected plants of the cultivar Leccino strongly modulates the genes involved in embolism sensing and refilling.

Peroxisomes in higher plant cells are known to differentiate into at least three different classes, namely, glyoxysomes, leaf peroxisomes, and unspecialized peroxisomes, depending on the cell types. In germinating fatty seedlings, glyoxysomes that first appear in the etiolated cotyledonary cells are functionally transformed into leaf peroxisomes during greening. Subsequently, the organelles are transformed back into glyoxysomes during senescence of the cotyledons. Flexibility of function is a distinct feature of plant peroxisomes. This article briefly describes recent studies of the regulatory mechanisms involved in the changes of the function of plant peroxisomes.

This paper is devoted to the analysis of the impact of changes in olive urban forests affected by Xylella fastidiosa on ecosystem services. The focus is on microclimate and thermal comfort evaluated by two indices: the temperature of equivalent perception (TEP) and the predicted mean vote (PMV), which take into account both microclimate parameters and personal factors (heat resistance of clothing and human activity). The work has been carried out through (i) a qualitative analysis of the potential ecosystem services changes caused by temporary transition from olive groves to uncultivated soil, (ii) a study of the potential change of land use from monumental olive groves to other types of use, and (iii) a quantitative analysis on microclimate impact due to the loss of ecosystem services in two selected neighborhoods located in the Apulia region and chosen due to their proximity to the urban context. The analysis revealed that (i) direct effects on ecosystem services are principally linked with regulation functions and cultural services, (ii) a critical loss of cultural value of monumental olive groves occurred in the two neighborhoods, (iii) such a loss may lead to an increase of TEP and PMV, indicating a decrease of thermal comfort in the whole neighborhoods. Thus, it is necessary to plan the replanting policies of the use of the areas affected by X. fastidiosa not only in terms of agricultural planning but also in terms of landscape, urban planning, and human well-being.

In this work, for the first time, were analyzed mulberry genotypes grown in Apulia (Southern Italy, Salento region) were analyzed. Two local varieties of Morus alba (cv. Legittimo nero and cv. Nello) and one of Morus nigra were characterized for content in simple sugars, organic acids, phenols, anthocyanins; fruit antioxidant activity (AA) was also evaluated by three different methods (2,2-Diphenyl-1-picrylhydrazyl, DPPH; 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS; and Ferric reducing antioxidant potential, FRAP test). The results showed that the sugars amount ranged between 6.29 and 7.66 g/100 g fresh weight (FW) while the malic and citric acids content was low, at about 0.1–1 g/100 g FW. Mulberries are a good source of phenols which are present in higher values in M. nigra and M. alba cv. Legittimo nero (485 and 424 mg Gallic Acid Equivalent (GAE)/ 100 g FW, respectively). The high performance liquid chromatography/diode array detector/mass spectrometry (HPLC/DAD/MS) analysis identified 5 main anthocyanin compounds present in different concentrations in each variety of mulberry: cyanidin 3-sophoroside, cyanidin 3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-glucoside, pelargonidin 3-rutinoside. The highest concentration of anthocyanins was determined in Morus alba Legittimo (about 300 mg/100 g FW) while the lowest content (about 25 mg/100 g FW) was measured in M. alba cv. Nello. Morus nigra showed a good AA in comparison with the different M. alba genotypes with all the used methods; its AA was equal to 33, 26 and 21 μmols Trolox/g FW when using DPPH, ABTS and FRAP tests, respectively. All genotypes showed an anti-inflammatory activity (measured by cyclooxygenase (COX) inhibitory assay) which was also compared with two commercial anti-inflammatory drugs. The data obtained support the high biological qualities of mulberry fruits and their diffusion in human nutrition.

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The recent outbreak of the Olive Quick Decline Syndrome (OQDS), caused by Xylella fastidiosa subsp. pauca (Xf), is dramatically altering ecosystem services in the peninsula of Salento (Apulia Region, southeastern Italy). Here we report the accomplishment of several exploratory missions in the Salento area, resulting in the identification of thirty paucisymptomatic or asymptomatic plants in olive orchards severely affected by the OQDS. The genetic profiles of such putatively resistant plants (PRPs), assessed by a selection of ten simple sequence repeat (SSR) markers, were compared with those of 141 Mediterranean cultivars. Most (23) PRPs formed a genetic cluster (K1) with 22 Italian cultivars, including ‘Leccino’ and ‘FS17’, previously reported as resistant to Xf. The remaining PRPs displayed relatedness with genetically differentiated germplasm, including a cluster of Tunisian cultivars. Markedly lower colonization levels were observed in PRPs of the cluster K1 with respect to control plants. Field evaluation of four cultivars related to PRPs allowed the definition of partial resistance in the genotypes ‘Frantoio’ and ‘Nocellara Messinese’. Some of the PRPs identified in this study might be exploited in cultivation, or as parental clones of breeding programs. In addition, our results indicate the possibility to characterize resistance to Xf in cultivars genetically related to PRPs.

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M. 1993. Purification and characterization of aconitase isoforms from etiolated pumpkin cotyledons. -Physiol. Plant. 88: 485-492.Although aconitase (EC 4.2.1.3) is involved in the glyoxylate cycle, which is localized in glyoxysomes, we detected very low aconitase activity in glyoxysomal fractions after sucrose gradient centrifugation of extracts prepared from etiolated pumpkin (Cucurbita sp.) cotyledons. Two aconitase isoforms were purified to homogeneity, albeit in low yield, by hydrophobic interaction, hydroxylapatite and anion exchange chromatography. They were designated Aco 1 and Aco II; both were shown to be monomeric proteins of M, 100000 or 98000 by gel filtration and SDS-PAGE analysis, respectively; isoelectric points were 5.0 and 4.8, respectively. Kinetic studies revealed similarities between Aco 1 and Aco II. A third aconitase isoform (Aco III) was revealed but not purified to homogeneity.