olive quick decline syndrome
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Pathogens ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 53
Author(s):  
Angela Brunetti ◽  
Antonio Matere ◽  
Valentina Lumia ◽  
Vittorio Pasciuta ◽  
Valeria Fusco ◽  
...  

Olive trees are infected and damaged by Botryosphaeriaceae fungi in various countries. The botryosphaeriaceous fungus Neofusicoccum mediterraneum is highly aggressive and is a major concern for olive groves in Spain and California (USA), where it causes ‘branch and twig dieback’ characterized by wood discoloration, bark canker, and canopy blight. During surveys of olive groves in Apulia (southern Italy), we noticed that—in some areas—trees were heavily affected by severe branch and twig dieback. In addition, chlorosis and the appearance of red-bronze patches on the leaf preceded the wilting of the foliage, with necrotic leaves persisting on the twigs. Given the severity of the manifestation in zones also subject to olive quick decline syndrome (OQDS) caused by Xylella fastidiosa subsp. pauca, we investigated the etiology and provide indications for differentiating the symptoms from OQDS. Isolation from diseased wood samples revealed a mycete, which was morphologically and molecularly identified as N. mediterraneum. The pathogenicity tests clearly showed that this fungus is able to cause the natural symptoms. Therefore, also considering the low number of tested samples, N. mediterraneum is a potential causal agent of the observed disease. Specifically, inoculation of the twigs caused complete wilting in two to three weeks, while inoculation at the base of the stem caused severe girdling wedge-shaped cankers. The growth rate of the fungus in in vitro tests was progressively higher from 10 to 30 °C, failing to grow at higher temperatures, but keeping its viability even after prolonged exposure at 50 °C. The capacity of the isolate to produce catenulate chlamydospores, which is novel for the species, highlights the possibility of a new morphological strain within N. mediterraneum. Further investigations are ongoing to verify whether additional fungal species are involved in this symptomatology.


Author(s):  
Isis Gabriela Barbosa Carvalho ◽  
Mariana Bossi Esteves ◽  
Joyce Adriana Froza ◽  
Heloisa Thomazi Kleina ◽  
Reinaldo Rodrigues de Souza Neto ◽  
...  

Based on genomic information, the Xylella fastidiosa bacterium is classified into three main subspecies: fastidiosa, multiplex and pauca. These different subspecies are naturally transmitted through vector insects, known as sharpshooters, which feed on the sap of xylem vessels of plants, where the bacteria colonize. Mainly due to the obstruction in the transport of water and mineral salts in these conducting vessels, the X. fastidiosa bacterium causes serious diseases in different cultures of economic interest. In Brazil, this phytopathogen was detected for the first time in plum trees, a crop in which the multiplex subspecies is responsible for the disease known as plum leaf scald. Subsequently, the pauca subspecie was associated with citrus variegated chlorosis in sweet orange orchards in São Paulo State. In the same state, the pauca subspecie was also found in coffee plants causing atrophy of the coffee tree branches, a disease whose damage has not been quantified yet. Recently, the pauca subspecie has also been found in olive trees, causing the olive quick decline syndrome, reported in the southeast region, especially in the Serra da Mantiqueira region. In this review, specific aspects of these diseases were focused, as well as measures that can be adopted as management.


2021 ◽  
Vol 7 (12) ◽  
Author(s):  
Anne Sicard ◽  
Maria Saponari ◽  
Mathieu Vanhove ◽  
Andreina I. Castillo ◽  
Annalisa Giampetruzzi ◽  
...  

The invasive plant pathogen Xylella fastidiosa currently threatens European flora through the loss of economically and culturally important host plants. This emerging vector-borne bacterium, native to the Americas, causes several important diseases in a wide range of plants including crops, ornamentals, and trees. Previously absent from Europe, and considered a quarantine pathogen, X. fastidiosa was first detected in Apulia, Italy in 2013 associated with a devastating disease of olive trees (Olive Quick Decline Syndrome, OQDS). OQDS has led to significant economic, environmental, cultural, as well as political crises. Although the biology of X. fastidiosa diseases have been studied for over a century, there is still no information on the determinants of specificity between bacterial genotypes and host plant species, which is particularly relevant today as X. fastidiosa is expanding in the naive European landscape. We analysed the genomes of 79 X . fastidiosa samples from diseased olive trees across the affected area in Italy as well as genomes of the most genetically closely related strains from Central America. We provided insights into the ecological and evolutionary emergence of this pathogen in Italy. We first showed that the outbreak in Apulia is due to a single introduction from Central America that we estimated to have occurred in 2008 [95 % HPD: 1930–2016]. By using a combination of population genomic approaches and evolutionary genomics methods, we further identified a short list of genes that could play a major role in the adaptation of X. fastidiosa to this new environment. We finally provided experimental evidence for the adaptation of the strain to this new environment.


2021 ◽  
Vol 9 (8) ◽  
pp. 1771
Author(s):  
Massimiliano Morelli ◽  
José Manuel García-Madero ◽  
Ángeles Jos ◽  
Pasquale Saldarelli ◽  
Crescenza Dongiovanni ◽  
...  

Since 2013, Xylella fastidiosa Wells et al. has been reported to infect several hosts and to be present in different areas of Europe. The main damage has been inflicted on the olive orchards of southern Apulia (Italy), where a severe disease associated with X. fastidiosa subspecies pauca strain De Donno has led to the death of millions of trees. This dramatic and continuously evolving situation has led to European and national (Italian and Spanish) measures being implemented to reduce the spread of the pathogen and the associated olive quick decline syndrome (OQDS). Research has been also carried out to find solutions to better and directly fight the bacterium and its main insect vector, Philaenus spumarius L. In the course of this frantic effort, several treatments based on chemical or biological substances have been tested, in addition to plant breeding techniques and integrated pest management approaches. This review aims to summarize the attempts made so far and describe the prospects for better management of this serious threat, which poses alarming questions for the future of olive cultivation in the Mediterranean basin and beyond.


Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1035
Author(s):  
Ugo Picciotti ◽  
Nada Lahbib ◽  
Valdete Sefa ◽  
Francesco Porcelli ◽  
Francesca Garganese

The Philaenus spumarius L. (Hemiptera Aphrophoridae) is a xylem-sap feeder vector that acquires Xylella fastidiosa subsp. pauca ST53 during feeding on infected plants. The bacterium is the plant pathogen responsible for olive quick decline syndrome that has decimated olive trees in Southern Italy. Damage originates mainly from the insect vector attitude that multiplies the pathogen potentialities propagating Xf in time and space. The principal action to manage insect-borne pathogens and to contain the disease spread consists in vector and transmission control. The analysis of an innovative and sustainable integrated pest management quantitative strategy that targets the vector and the infection by combining chemical and physical control means demonstrates that it is possible to stop the Xylella invasion. This review updates the available topics addressing vectors’ identification, bionomics, infection management, and induced disease by Xylella invasion to discuss major available tools to mitigate the damage consequent to the disease.


2021 ◽  
Vol 12 ◽  
Author(s):  
Stefano Pavan ◽  
Marzia Vergine ◽  
Francesca Nicolì ◽  
Erika Sabella ◽  
Alessio Aprile ◽  
...  

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.


Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 446
Author(s):  
Luca Lombardo ◽  
Pierluigi Rizzo ◽  
Carmine Novellis ◽  
Veronica Vizzarri

Xylella fastidiosa subsp. pauca, strain CoDiRO is the bacterium responsible for the onset of the disease known as the olive quick decline syndrome, which has been causing a phytosanitary and economic emergency in the Apulia region since 2013. To date, three insect species have been identified as pathogenic carriers of X. fastidiosa. With the advancement of the infection front, and the possibility of pathogenic insects being “hitchhiked” over long distances, the monitoring of the vectors of X. fastidiosa in the Italian regions bordering Apulia is an increasingly contingent issue for the rapid containment of the bacterium and the protection of the olive-growing heritage. Accordingly, the present research concerned the capture and recognition of the vector insects of X. fastidiosa in the upper Ionian coasts of Calabria (Italy) to evaluate the possible presence of the bacterium through molecular diagnostic techniques. The sampling allowed us to ascertain the presence of Philaenus spumarius and Neophilaenus campestris and their preferential distribution in olive groves and meadows, whereas all the 563 individuals tested negative for the pathogen.


2021 ◽  
Author(s):  
Nancy Walker ◽  
Kathryn Rankin ◽  
Siul Ruiz ◽  
Daniel McKay Fletcher ◽  
Katherine Williams ◽  
...  

<p>Photosynthesis relies on the transport of water and sugars from roots to leaves facilitated by two key tissues: xylem and phloem. Blockages in the xylem/phloem, either by structures formed by the pathogen itself or those formed by the plant as a defence mechanism, disrupt the soil-plant-atmosphere continuum and cause many vascular plant disease symptoms.<em> Xylella fastidiosa </em>(<em>X. fastidiosa</em>) is a bacterium that colonises internal plant vascular networks causing pathogenic effects on several commercially important crops, including those associated with the olive quick decline syndrome causing devastating olive decline in Apulia, Southern Italy.<em> </em>Despite a growing research effort since the recent detection of <em>X. fastidiosa</em> in Europe, the exact processes leading to <em>X. fastidiosa</em> disease symptoms are not fully understood due to difficulties in observing internal plant structures.</p> <p>Our goal is to utilise models to elucidate fundamental processes that lead to olive quick decline syndrome. We are developing a mathematical model describing within-host biofilm development that predicts water-stresses that ultimately inhibit plant functionality. Our approach is centred on the assumption that the biofilm structure is determined by the arrangement of extracellular polysaccharide (EPS) molecules, and as such, our model contains a polymer-physical description of <em>X. fastidiosa</em> biofilm formation dynamics. We used our model, requiring minimal empirical assumptions, to replicate biofilm aggregation observed by microfluidics. We have also produced X-ray Computed Tomography (XCT) images of vascular networks in both resistant and susceptible olive cultivars. We are using these images to test whether susceptibility is correlated with morphological differences that might influence fluid flow through the plant. This work improves the understanding of possible cultivar resistance mechanisms to aid informed breeding and orchard management, and model simulations will provide insights for understanding xylem blockages and their relation to observed symptom severity.</p>


Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 772
Author(s):  
Chiara Roberta Girelli ◽  
Laura Del Coco ◽  
Federica Angilè ◽  
Marco Scortichini ◽  
Francesco Paolo Fanizzi

Xylella fastidiosa subsp. pauca, is a bacterial phytopathogen associated with the “olive quick decline syndrome” (OQDS) causing severe economic losses to olive groves in Salento area (Apulia, Italy). In a previous work, we analyzed by 1H-NMR the metabolic pattern of naturally infected Ogliarola salentina and Cellina di Nardò susceptible cultivars untreated and treated with a zinc-copper citric acid biocomplex and we observed the treatment related variation of the disease biomarker quinic acid. In this study, we focused also on the Leccino cultivar, known to exhibit tolerance to the disease progression. The 1H-NMR-based metabolomic approach was applied with the aim to characterize the overall metabolism of tolerant Leccino in comparison with the susceptible cultivars Ogliarola salentina and Cellina di Nardò under periodic mid-term treatment. In particular, we studied the leaf extract molecular patterns of naturally infected trees untreated and treated with the biocomplex. The metabolic Leccino profiles were analyzed for the first time and compared with those exhibited by the susceptible Cellina di Nardò and Ogliarola salentina cultivars. The study highlighted a specificity in the metabolic response of the tolerant Leccino compared to susceptible cultivars. These differences provide useful information to describe the defensive mechanisms underlying the change of metabolites as a response to the infection, and the occurrence of different levels of disease, season and treatment effects for olive cultivars.


Author(s):  
Sabrina Di Masi ◽  
Giuseppe E. De Benedetto ◽  
Cosimino Malitesta ◽  
Maria Saponari ◽  
Cinzia Citti ◽  
...  

AbstractOlive quick decline syndrome (OQDS) is a disorder associated with bacterial infections caused by Xylella fastidiosa subsp. pauca ST53 in olive trees. Metabolic profile changes occurring in infected olive trees are still poorly investigated, but have the potential to unravel reliable biomarkers to be exploited for early diagnosis of infections. In this study, an untargeted metabolomic method using high-performance liquid chromatography coupled to quadrupole-time-of-flight high-resolution mass spectrometry (HPLC-ESI-Q-TOF-MS) was used to detect differences in samples (leaves) from healthy (Ctrl) and infected (Xf) olive trees. Both unsupervised and supervised data analysis clearly differentiated the groups. Different metabolites have been identified as potential specific biomarkers, and their characterization strongly suggests that metabolism of flavonoids and long-chain fatty acids is perturbed in Xf samples. In particular, a decrease in the defence capabilities of the host after Xf infection is proposed because of a significant dysregulation of some metabolites belonging to flavonoid family. Moreover, oleic acid is confirmed as a putative diffusible signal factor (DSF). This study provides new insights into the host-pathogen interactions and confirms LC-HRMS-based metabolomics as a powerful approach for disease-associated biomarkers discovery in plants. Graphical abstract


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