Search Results (56)

Since its first detection in 2013, Xylella fastidiosa subsp. pauca (Xfp) has caused a devastating Olive Quick Decline Syndrome (OQDS) outbreak in Southern Italy. Effective disease surveillance and treatment strategies are urgently needed to mitigate its impact. This study investigates the short-term (1.5 years) effects of thymol-based treatments on infected olive trees of the susceptible cultivar Cellina di Nardò in two orchards in Salento, Apulia region. Twenty trees per trial received a 3% thymol solution either alone or encapsulated in a cellulose nanoparticle carrier. Over two years, sap flux density and canopy-transmitted solar radiation were monitored using TreeTalker sensors, and spectral greenness indices were calculated. Xfp cell concentrations in plant tissues were quantified via qPCR. Neither thymol treatment halted disease progression nor significantly reduced bacterial load, though the Xfp cell concentration reduction increased over time in the preventive trial. Symptomatic trees exhibited increased sap flux density, though the treatment mitigated this effect in the curative trial. Greenness indices remained lower in infected trees, but the response to symptom severity was delayed. These findings underscore the need for longer-term studies, investigation of synergistic effects with other phytocompounds, and integration of real-time sensor data into adaptive disease management protocols. Full article

The decline of perennial plant species, including oak, olive, and kiwifruit, is a phenomenon currently observed in many areas of the world. In this review, such species are chosen precisely because, despite the differences in their botany, native distribution, and current utilization, they are all affected by significant global or local declines. An analysis of the main common causes involved could be useful for a better understanding of the phenomenon. Quercus species are impacted by “Chronic Oak Decline” (COD), “Sudden Oak Decline” (SOD), and “Acute Oak Decline” (AOD). In Italy, olive groves are severely damaged by “Olive Quick Decline Syndrome”, whereas kiwifruit orchards are struck by “Kiwifruit Vine Decline Syndrome” (KVDS). Among the abiotic inciting stressors, drought, warmer temperatures, and waterlogging, all within a climate change scenario, are involved in all declines described herein as well as in plant dysbiosis. The involvement of some aggressive phytopathogens is another common feature of all these declines. Oomycetes contribute to COD, SOD, and KVDS; Xylella fastidiosa subsp. pauca and Botryosphaeriaceae affect olive, and some enterobacteria are involved in AOD, all representing decisive contributing factors. These declines are quite complex, and a comprehensive approach is required to dissect all the facets involved. A better understanding of altered host–microbial community relationships can lead to a more tailored approach to understanding and managing declines. Maintaining tree resilience in a warmer Earth remains a primary goal to achieve for preserving both natural ecosystems and profitable crops. Full article

Xylella fastidiosa subsp. pauca (Xfp), a quarantine pathogen in the European Union, severely threatens Mediterranean olive production, especially in southern Italy, where Olive Quick Decline Syndrome (OQDS) has devastated Apulian olive groves. This study addresses the urgent need to identify resistant olive genotypes by monitoring 16 potentially tolerant genotypes over six years, assessing symptom severity and bacterial load. These genotypes, which survived in heavily infected areas, showed varied responses to Xfp; some maintained low symptom severity with minimal bacterial presence (high or undetectable Cq values), while others exhibited increased bacterial loads yet remained asymptomatic or showed limited canopy desiccation. SSR markers were used to investigate the genetic relationships among these genotypes and other widespread Mediterranean cultivars, showing genetic similarity with the resistant ones such as the Albanian Kalinjot and the Greek Leucocarpa, as well as with local Apulian cultivars, highlighting the potential of local and Mediterranean olive germplasm for Xfp resistance. This study integrates phenotypic responses with genetic knowledge to support the development of conservation strategies that will enhance the genetic diversity of Apulian olive cultivars. In addition, by focusing on the resilience of the different olive genotypes, this research aims to protect the traditional cultivars from the emerging threats, thus preserving the ecological and cultural heritage of the olive biodiversity of the Mediterranean region. Full article

Xylella fastidiosa is an aerobic, Gram-negative bacterium that is responsible for many plant diseases. The bacterium is the causal agent of Pierce’s disease in grapes and is also responsible for citrus variegated chlorosis, peach phony disease, olive quick decline syndrome and leaf scorches of various species. The production of biofilm is intrinsically linked with persistence and transmission in X. fastidiosa. Biofilm formation is regulated by members of the Diffusible Signal Factor (DSF) quorum sensing signalling family which are comprised of a series of long chain cis-unsaturated fatty acids. This article describes the evaluation of a library of N-acyl sulfonamide bioisosteric analogues of BDSF, XfDSF1 and XfDSF2 for their ability to control biofilm production in X. fastidiosa. The compounds were screened against both the wild-type strain Temecula and an rpfF* mutant which can perceive but not produce XfDSF. Planktonic cell abundance was measured via OD600 while standard crystal violet assays were used to determine biofilm biomass. Several compounds were found to be effective biofilm inhibitors depending on the nature of the sulfonamide substituent. The findings reported here may provide future opportunities for biocontrol of this important plant pathogen. Full article

Xylella fastidiosa subsp. pauca (Xfp) is a significant threat to Mediterranean agriculture, particularly impacting olive trees in southern Italy, causing Olive Quick Decline Syndrome. Resistant olive cultivars, such as ‘Leccino’ and ‘Fs-17’, have been identified as alternatives to restore the oliviculture within the infected areas. ‘Frantoio’ and ‘Cipressino’ are included in ongoing studies on genetic resistance to Xfp. The mechanization of olive harvesting is essential for reducing production costs in the olive oil sector. Two systems, trunk shakers and over-the-row machines, are used depending on the tree density and canopy structure, with super-high-density systems offering advantages in terms of cost and efficiency. This study investigates the feasibility of using simple and non-destructive indices to assess the optimal mechanical harvesting time. Different physical ripening indices, including detachment force, fresh weight, pigmentation, and firmness, were measured on four olive cultivars (‘Fs-17’, ‘Leccino’, ‘Frantoio’, ‘Cipressino’) in southern Italy over two years. The study found that the pigmentation index had a strong relationship with the detachment index, particularly for ‘Fs-17’, and ‘Leccino’, providing a reliable non-destructive measure for optimal harvesting time. The results indicate that the optimal harvesting times for mechanical harvesting are early September for ‘Cipressino’, early October for ‘Fs-17’, and mid-October for ‘Frantoio’ and ‘Leccino’. Full article

Background/Objectives: Acute kidney injury (AKI) syndrome is distinguished by a quick decline in renal excretory capacity and usually diagnosed by the presence of elevated nitrogen metabolism end products and/or diminished urine output. AKI frequently occurs in hospital patients, and there are no existing specific treatments available to diminish its occurrence or expedite recovery. For an extended period in the food industry, Pediococcus acidilactici has been distinguished by its robust bacteriocin production, effectively inhibiting pathogen growth during fermentation and storage. Methods: In this study, the aim is to assess the effectiveness of P. acidilactici GKA4, dead probiotic GKA4, and postbiotic GKA4 against cisplatin-induced AKI in an animal model. The experimental protocol involves a ten-day oral administration of GKA4, dead probiotic GKA4, and postbiotic GKA4 to mice, with a cisplatin intraperitoneal injection being given on the seventh day to induce AKI. Results: The findings indicated the significant alleviation of the renal histopathological changes and serum biomarkers of GKA4, dead probiotic GKA4, and postbiotic GKA4 in cisplatin-induced nephrotoxicity. GKA4, dead probiotic GKA4, and postbiotic GKA4 elevated the expression levels of HO-1 and decreased the expression levels of Nrf-2 proteins. In addition, the administration of GKA4, dead probiotic GKA4, and postbiotic GKA4 significantly reduced the expression of apoptosis-related proteins (Bax, Bcl-2, and caspase 3), autophagy-related proteins (LC3B, p62, and Beclin1), and endoplasmic reticulum (ER) stress-related proteins (GRP78, PERK, ATF-6, IRE1, CHOP, and Caspase 12) in kidney tissues. Notably, GKA4, dead probiotic GKA4, and postbiotic GKA4 also upregulated the levels of proteins related to organic anion transporters and organic cation transporters. Conclusions: Overall, the potential therapeutic benefits of GKA4, dead probiotic GKA4, and postbiotic GKA4 are significant, particularly after cisplatin treatment. This is achieved by modulating apoptosis, autophagy, ER stress, and transporter proteins to alleviate oxidative stress. Full article

Olive Quick Decline Syndrome (OQDS) associated with Xylella fastidiosa subsp. pauca is one of the most destructive diseases of olive trees in the Salento Peninsula (Southern Italy), particularly on the cultivars Cellina di Nardò and Ogliarola Salentina. This study proposes the NuovOlivo protocol as a management strategy to permit coexistence between X. fastidiosa subsp. pauca and olive drupes and extra-virgin oil production. Thirty-two private olive orchards affected by OQDS and cultivated following the standard agronomic techniques in use in the area were surveyed during the 2019–2023 olive-growing seasons. Tested cultivars included Cellina di Nardò, Ogliarola Salentina, Coratina, Ascolana Tenera, Nociara, Leccino, and Bella di Cerignola. At the beginning of the protocol application, the susceptible plants showed OQDS symptom severity of 40–80% and did not produce olives or oil, while the resistant(?)/tolerant cultivars exhibited a 2–8% leaf scorch and a drupe production less than 1–2 kg/plant. After the removal of dry branches in January–February, plants were sprayed two times per year (preferably in March and October) with NuovOlivo^®, a mixture of aqueous botanical extracts esterified in the presence of sodium hydroxide with vegetable oils and activated at the time of use with sodium bicarbonate. In all the orchards, a slow-release fertilizer was distributed, and weeds were controlled by mowing or chopping. Upon eventual appearance, the dry twigs were removed. Treated olive trees produced new vegetation, rebuilt their foliage, reduced OQDS symptoms, and turned out cluster inflorescence and drupes. The drupes yield was 6.67–51.36 kg per plant, with an average of 13.19% in extra-virgin olive oil (free acidity 0.01–0.2%). Plants used as controls showed OQDS symptoms and were unproductive, and newly formed shoots were desiccated. The proposed protocol promotes, supports, and restores new vegetation, flowers, fruits, and oil production of the treated olive plants affected by OQDS without losing susceptible olive plants. The Apulian landscape and economy, based on olive presence and production, could be also safeguarded. Full article

The initial outbreak of Xylella fastidiosa subsp. pauca (Xfp) on olive groves in Salento (Apulia, Italy) dates back to the years 2008 and 2009 when extensive twig and branch diebacks were observed in the area of Gallipoli area (province of Lecce). Subsequently, the bacterium also spread northwards to other areas of Apulia. In many cases, entire olive groves, also including the centennial ones, died. After the crown collapse, in many cases, it has been observed that the suckers are resprouting at the base of the trunk. After two to three years, such suckers usually died as well. However, during the last four to five years, in the first Xfp outbreak area, a complete restoration of the crown of the Xfp-susceptible cultivars Ogliarola salentina and Cellina di Nardò has been noticed. Such trees or olive groves also started to yield again. To monitor this tree resilience phenomenon, together with local non-profit organizations, a survey in the province of Lecce has been carried out to find olive groves for which any curative or agronomical practices have been applied since the bacterium outbreak. Resilient olive groves are scattered in many municipalities all over the province of Lecce. The phenomenon regards both young and adult olive groves and also includes some centennial trees. In many cases, the trees are yielding fruits, and farmers started to cultivate them again. Olive resilience in Salento is already being studied and can represent a significant opportunity to restore the local and valuable olive germplasm. Full article

The fungi Botryosphaeriaceae are involved in olive declines in both the world hemispheres and in all continents where this species is cultivated. In Salento (Apulia, Italy), the Botryosphaeriaceae Neofusicoccum mediterraneum and N. stellenboschiana have been reported as the agents of a branch and twig dieback that overlaps with olive quick decline syndrome caused by Xylella fastidiosa subsp. pauca. In this study, we report the finding of Diplodia seriata, another Botryosphaeriaceae species, in Salento in Xylella fastidiosa-infected olive trees affected by symptoms of branch and twig dieback. Given that its presence was also reported in olive in the Americas and in Europe (Croatia) with different degrees of virulence, we were prompted to assess its role in the Apulian decline. We identified representative isolates based on morphological features and a multilocus phylogeny. In vitro tests showed that the optimum growth temperature of the isolates is around 25–30 °C, and that they are highly thermo-tolerant. In pathogenicity trials conducted over eleven months, D. seriata expressed a very low virulence. Nonetheless, when we imposed severe water stress before the inoculation, D. seriata significatively necrotized bark and wood in a time frame of 35 days. Moreover, the symptoms which resulted were much more severe in the trial performed in summer compared with that in autumn. In osmolyte-supplemented media with a water potential from −1 to −3 Mpa, the isolates increased or maintained their growth rate compared with non-supplemented media, and they also grew, albeit to a lesser extent, on media with a water potential as low as −7 Mpa. This suggests that olives with a low water potential, namely those subjected to drought, may offer a suitable environment for the fungus’ development. The analysis of the meteorological parameters, temperatures and rainfall, in Salento in the timeframe 1989–2023, showed that this area is subjected to a progressive increase of temperature and drought during the summer. Thus, overall, D. seriata has to be considered a contributor to the manifestation of branch and twig dieback of olive in Salento. Coherently with the spiral decline concept of trees, our results suggest that heat and drought act as predisposing/inciting factors facilitating D. seriata as a contributor. The fact that several adverse factors, biotic and abiotic, are simultaneously burdening olive trees in Salento offers a cue to discuss the possible complex nature of the olive decline in Salento. Full article

Mass production is a prerequisite for using natural enemies in integrated pest management and organic farming. Natural enemies in agroecosystems include predators that prey on insects, which they can subdue while maintaining adequate pest population densities. The Leafhopper Assassin Bug (LAB), Zelus renardii, can be a natural enemy in agroecosystems, selecting its prey for size and mobility. Some of LAB’s prey include Philaenus spumarius (L.), Bactrocera oleae (Rossi), Drosophila suzukii (Matsumura), and Macrohomotoma gladiata Kuwayama, suggesting this reduviid for biocontrol agent in various contexts. We reared LABs for two subsequent broods offering living prey and artificial diets. Our data show that the rearing of Z. renardii is feasible with oligidic, meridic, and holidic artificial formulations. Four artificial diets allowed the complete post-embryonic development of LABs in captivity for two successive generations. The accumulated degree-days (ADDs) accurately predict the growth of LABs based on heat accumulation, estimating that up to three generations could grow per year in captivity at the experimented T°C. Full article

Xylella fastidiosa subsp. pauca ST53 (XFP), the causal agent of olive quick decline syndrome (OQDS), was thoroughly investigated after a 2013 outbreak in the Salento region of Southern Italy. Some trees from Ogliarola Salentina and Cellina di Nardò, susceptible cultivars in the Gallipoli area, the first XFP infection hotspot in Italy, have resprouted crowns and are starting to flower and yield fruits. Satellite imagery and Normalized Difference Vegetation Index analyses revealed a significant improvement in vegetation health and productivity from 2018 to 2022 of these trees. Lipid molecules have long been recognized as plant defense modulators, and recently, we investigated their role in XFP-positive hosts and in XFP-resistant as well as in XFP-susceptible cultivars of olive trees. Here, we present a case study regarding 36 olive trees (12 XFP-positive resprouting, 12 XFP-positive OQDS-symptomatic, and 12 XFP-negative trees) harvested in 2022 within the area where XFP struck first, killing millions of trees in a decade. These trees were analyzed for some free fatty acid, oxylipin, and plant hormones, in particular jasmonic and salicylic acid, by targeted LC-MS/MS. Multivariate analysis revealed that lipid markers of resistance (e.g., 13-HpOTrE), along with jasmonic and salicylic acid, were accumulated differently in the XFP-positive resprouting trees from both cultivars with respect to XFP-positive OQDS symptomatic and XFP-negative trees, suggesting a correlation of lipid metabolism with the resprouting, which can be an indication of the resiliency of these trees to OQDS. This is the first report concerning the resprouting of OQDS-infected olive trees in the Salento area. Full article

The detection of Xylella fastidiosa in Portugal occurred through prospection in 2019 in Vila Nova de Gaia, Porto, in plants of Lavandula dentata L. Currently, in Portugal, there are 18 Xylella fastidiosa Demarcated Zones (DZs). The main objective of this study is to gain a comprehensive understanding of this problem within the defined Demarcated Zones in the North Region of Portugal from 2019 to June 2023. This work comprised two phases: the prospection phase (inspecting plants, sampling, and submission of samples to the laboratory) and the research phase (collecting and organizing data and statistical treatment). Our findings provide essential insights, suggesting that the Northern Region of Portugal is highly conducive to Xylella fastidiosa. Portugal has Xf-preferred hosts such as the olive tree, orange tree, Laurus nobilis, Rosa spp., Nerium oleander L., Pelargonium sp., Hedera helix L., and Lavandula dentata L. Portugal’s favorable environmental factors such as temperature and humidity can have an important role in influencing the interaction between bacteria and hosts. Nevertheless, it is crucial to consider variations in the behavior of insect vectors, as these variations can limit the prevalence of the disease. Activities like the transport of infected planting materials from the first Demarcated Zone of the Area Metropolitana do Porto could be associated with the introduction and spread of Xylella fastidiosa, potentially triggering new disease outbreaks in the country. Our findings confirm the alarming spread of Xylella fastidiosa across Portugal. Factors such as the presence of insect vectors, abundance of host plants, and climate suitability play pivotal roles in Xylella fastidiosa dispersal. We recommend that countries identified with relatively high risk, like Portugal, undertake thorough individual risk analyses. The implementation of preventive measures and, if necessary, the enhancement of surveillance systems for early detection of Xylella fastidiosa in plants and insect vectors are crucial steps. Full article

In 2013, an outbreak of Xylella fastidiosa (Xf) was identified for the first time in Europe, in the extreme south of Italy (Apulia, Salento territory). The locally identified subspecies pauca turned out to be lethal for olive trees, starting an unprecedented phytosanitary emergency for one of the most iconic cultivations of the Mediterranean area. Xf pauca (Xfp) is responsible for a severe disease, the olive quick decline syndrome (OQDS), spreading epidemically and with dramatic impact on the agriculture, the landscape, the tourism and the cultural heritage of this region. The bacterium, transmitted by insects that feed on xylem sap, causes rapid wilting in olive trees due to biofilm formation, which obstructs the plant xylematic vessels. The aim of this review is to perform a thorough analysis that offers a general overview of the published work, from 2013 to December 2023, related to the Xfp outbreak in Apulia. This latter hereto has killed millions of olive trees and left a ghostly landscape with more than 8000 square kilometers of infected territory, that is 40% of the region. The majority of the research efforts made to date to combat Xfp in olive plants are listed in the present review, starting with the early attempts to identify the bacterium, the investigations to pinpoint and possibly control the vector, the assessment of specific diagnostic techniques and the pioneered therapeutic approaches. Interestingly, according to the general set criteria for the preliminary examination of the accessible scientific literature related to the Xfp outbreak on Apulian olive trees, fewer than 300 papers can be found over the last decade. Most of them essentially emphasize the importance of developing diagnostic tools that can identify the disease early, even when infected plants are still asymptomatic, in order to reduce the risk of infection for the surrounding plants. On the other hand, in the published work, the diagnostic focus (57%) overwhelmingly encompasses all other possible investigation goals such as vectors, impacts and possible treatments. Notably, between 2013 and 2023, only 6.3% of the literature reports addressing the topic of Xfp in Apulia were concerned with the application of specific treatments against the bacterium. Among them, those reporting field trials on infected plants, including simple pruning indications, were further limited (6%). Full article

Xylella Fastidiosa has been recently detected for the first time in southern Italy, representing a very dangerous phytobacterium capable of inducing severe diseases in many plants. In particular, the disease induced in olive trees is called olive quick decline syndrome (OQDS), which provokes the rapid desiccation and, ultimately, death of the infected plants. In this paper, we analyse about two thousands pixels of MODIS satellite evapotranspiration time series, covering infected and uninfected olive groves in southern Italy. Our aim is the identification of Xylella Fastidiosa-linked patterns in the statistical features of evapotranspiration data. The adopted methodology is the well-known Fisher–Shannon analysis that allows one to characterize the time dynamics of complex time series by means of two informational quantities, the Fisher information measure (FIM) and the Shannon entropy power (SEP). On average, the evapotranspiration of Xylella Fastidiosa-infected sites is characterized by a larger SEP and lower FIM compared to uninfected sites. The analysis of the receiver operating characteristic curve suggests that SEP and FIM can be considered binary classifiers with good discrimination performance that, moreover, improves if the yearly cycle, very likely linked with the meteo-climatic variability of the investigated areas, is removed from the data. Furthermore, it indicated that FIM exhibits superior effectiveness compared to SEP in discerning healthy and infected pixels. Full article

Olive quick decline syndrome (OQDS) is a devastating plant disease caused by the bacterium Xylella fastidiosa (Xf). Exploratory missions in the Salento area led to the identification of putatively Xf-resistant olive trees (putatively resistant plants, PRPs) which were pauci-symptomatic or asymptomatic infected plants belonging to different genetic clusters in orchards severely affected by OQDS. To investigate the defense strategies employed by these PRPs to contrast Xf infection, the PRPs were analyzed for the anatomy and histology of xylem vessels, patterns of Xf distribution in host tissues (by the fluorescent in situ hybridization technique—FISH) and the presence of secondary metabolites in stems. The xylem vessels of the PRPs have an average diameter significantly lower than that of susceptible plants for each annual tree ring studied. The histochemical staining of xylem vessels highlighted an increase in the lignin in the parenchyma cells of the medullary rays of the wood. The 3D images obtained from FISH-LSM (laser scanning microscope) revealed that, in the PRPs, Xf cells mostly appeared as individual cells or as small aggregates; in addition, these bacterial cells looked to be incorporated in the autofluorescence signal of gels and phenolic compounds regardless of hosts’ genotypes. In fact, the metabolomic data from asymptomatic PRP stems showed a significant increase in compounds like salicylic acid, known as a signal molecule which mediates host responses upon pathogen infection, and luteolin, a naturally derived flavonoid compound with antibacterial properties and with well-known anti-biofilm effects. Findings indicate that the xylem vessel geometry together with structural and chemical defenses are among the mechanisms operating to control Xf infection and may represent a common resistance trait among different olive genotypes. Full article