scholarly journals Community Analysis of Culturable Sapwood Endophytes from Apulian Olive Varieties with Different Susceptibility to Xylella fastidiosa

Agronomy ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 9
Author(s):  
Arafat Hanani ◽  
Franco Valentini ◽  
Simona M. Sanzani ◽  
Franco Santoro ◽  
Serena A. Minutillo ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Xylella Fastidiosa ◽  
Community Analysis ◽  
Olive Tree ◽  
Symbiotic Association ◽  
Living Plant ◽  
Tree Protection ◽  
Olive Variety ◽  
Olive Varieties ◽  
Almost All

Endophytes are symptomless fungal and/or bacterial microorganisms found in almost all living plant species. The symbiotic association with their host plants by colonizing the internal tissues has endowed them as a valuable tool to suppress diseases, stimulate growth, and promote stress resistance. In this context, the study of culturable endophytes residing the sapwood of Apulian olives might be a promising control strategy for xylem colonizing pathogens as Xylella fastidiosa. To date, olive sapwood cultivable endophytes are still under exploration; therefore, this work pursues a study of cultivable endophytes occurrence variation in the sapwood of different olive varieties under the effect of seasonality, geographical coordinates, and X. fastidiosa infection status. Our study confirms the stability of sapwood endophytic culturable communities in the resistant olive variety and presents the seasonal and geographical fluctuation of olive trees’ sapwood endophytes. It also describes the diversity and occurrence frequency of fungal and bacterial genera, and finally retrieves some of the sapwood-inhabiting fungal and bacterial isolates, known as biocontrol agents of plant pathogens. Thus, the potential role of these bacterial and fungal isolates in conferring olive tree protection against X. fastidiosa should be further investigated.

scholarly journals Characterization and variation of bacterial and fungal communities from the sapwood of Apulian olive varieties with different susceptibility to Xylella fastidiosa

2020 ◽  
Author(s):  
Arafat Hanani ◽  
Franco Valentini ◽  
Giuseppe Cavallo ◽  
Simona Marianna Sanzani ◽  
Franco Santoro ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Olive Tree ◽  
Symbiotic Association ◽  
Living Plant ◽  
Tree Protection ◽  
Olive Variety ◽  
The Stability ◽  
Olive Varieties ◽  
Almost All

AbstractEndophytes are symptomless fungal and/or bacterial microorganisms found in almost all living plant species. The symbiotic association with their host plants by colonizing the internal tissues has endowed them as a valuable tool to suppress diseases, to stimulate growth, and to promote stress resistance. In this context, the identification of cultivable endophytes residing the sapwood of Apulian olives might be a promising control strategy for xylem colonizing pathogens as Xylella fatidiosa. To date, olive’s sapwood cultivable endophytes are still under exploration; therefore, this work pursues a study of diversity and occurrence variation of cultivable endophytes in the sapwood of different olive varieties under the effect seasonality, geographical coordinates, and X. fastidiosa infection status. Briefly, our study confirms the stability of sapwood cultivable endophytic communities in the resistant olive variety, presents the seasonal and geographical fluctuation of olive’s sapwood endophytes, describes the diversity and occurrence frequency of fungal and bacterial genera, and finally retrieves some of sapwood-inhabiting fungal and bacterial isolates are known as biocontrol agents of plant pathogens. Thus, the potential role of these bacterial and fungal isolates in conferring olive tree protection against X. fastidiosa should be further investigated.

scholarly journals Semi-Automatic Method for Early Detection of Xylella fastidiosa in Olive Trees Using UAV Multispectral Imagery and Geostatistical-Discriminant Analysis

2020 ◽  
Vol 13 (1) ◽  
pp. 14
Author(s):  
Annamaria Castrignanò ◽  
Antonella Belmonte ◽  
Ilaria Antelmi ◽  
Ruggiero Quarto ◽  
Francesco Quarto ◽  
...  
Keyword(s):  
Discriminant Analysis ◽  
Early Detection ◽  
Plant Pathogens ◽  
Early Stage ◽  
Xylella Fastidiosa ◽  
Mediterranean Countries ◽  
Parametric Classification ◽  
Aerial Vehicle ◽  
Olive Groves ◽  
Olive Trees

Xylella fastidiosa subsp. pauca (Xfp) is one of the most dangerous plant pathogens in the world. Identified in 2013 in olive trees in south–eastern Italy, it is spreading to the Mediterranean countries. The bacterium is transmitted by insects that feed on sap, and causes rapid wilting in olive trees. The paper explores the use of Unmanned Aerial Vehicle (UAV) in combination with a multispectral radiometer for early detection of infection. The study was carried out in three olive groves in the Apulia region (Italy) and involved four drone flights from 2017 to 2019. To classify Xfp severity level in olive trees at an early stage, a combined method of geostatistics and discriminant analysis was implemented. The results of cross-validation for the non-parametric classification method were of overall accuracy = 0.69, mean error rate = 0.31, and for the early detection class of accuracy 0.77 and misclassification probability 0.23. The results are promising and encourage the application of UAV technology for the early detection of Xfp infection.

scholarly journals Controlling the Spatial Spread of a Xylella Epidemic

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
Sebastian Aniţa ◽  
Vincenzo Capasso ◽  
Simone Scacchi
Keyword(s):  
Spatial Structure ◽  
Numerical Simulations ◽  
Control Strategies ◽  
Xylella Fastidiosa ◽  
Cost Effective ◽  
Olive Tree ◽  
Control Measures ◽  
Weed Biomass ◽  
Spatial Spread ◽  
Olive Trees

AbstractIn a recent paper by one of the authors and collaborators, motivated by the Olive Quick Decline Syndrome (OQDS) outbreak, which has been ongoing in Southern Italy since 2013, a simple epidemiological model describing this epidemic was presented. Beside the bacterium Xylella fastidiosa, the main players considered in the model are its insect vectors, Philaenus spumarius, and the host plants (olive trees and weeds) of the insects and of the bacterium. The model was based on a system of ordinary differential equations, the analysis of which provided interesting results about possible equilibria of the epidemic system and guidelines for its numerical simulations. Although the model presented there was mathematically rather simplified, its analysis has highlighted threshold parameters that could be the target of control strategies within an integrated pest management framework, not requiring the removal of the productive resource represented by the olive trees. Indeed, numerical simulations support the outcomes of the mathematical analysis, according to which the removal of a suitable amount of weed biomass (reservoir of Xylella fastidiosa) from olive orchards and surrounding areas resulted in the most efficient strategy to control the spread of the OQDS. In addition, as expected, the adoption of more resistant olive tree cultivars has been shown to be a good strategy, though less cost-effective, in controlling the pathogen. In this paper for a more realistic description and a clearer interpretation of the proposed control measures, a spatial structure of the epidemic system has been included, but, in order to keep mathematical technicalities to a minimum, only two players have been described in a dynamical way, trees and insects, while the weed biomass is taken to be a given quantity. The control measures have been introduced only on a subregion of the whole habitat, in order to contain costs of intervention. We show that such a practice can lead to the eradication of an epidemic outbreak. Numerical simulations confirm both the results of the previous paper and the theoretical results of the model with a spatial structure, though subject to regional control only.

Effectors of biotrophic fungal plant pathogens

2010 ◽  
Vol 37 (10) ◽  
pp. 913 ◽  
Author(s):  
Pamela H. P. Gan ◽  
Maryam Rafiqi ◽  
Adrienne R. Hardham ◽  
Peter N. Dodds
Keyword(s):  
Plant Tissue ◽  
Fungal Pathogen ◽  
Plant Pathogens ◽  
Plant Cells ◽  
Host Cells ◽  
Plant Proteins ◽  
Living Plant ◽  
Host Cytoplasm ◽  
Fungal Plant Pathogens ◽  
Biotrophic Fungi

Plant pathogenic biotrophic fungi are able to grow within living plant tissue due to the action of secreted pathogen proteins known as effectors that alter the response of plant cells to pathogens. The discovery and identification of these proteins has greatly expanded with the sequencing and annotation of fungal pathogen genomes. Studies to characterise effector function have revealed that a subset of these secreted pathogen proteins interact with plant proteins within the host cytoplasm. This review focuses on the effectors of intracellular biotrophic and hemibiotrophic fungal plant pathogens and summarises advances in understanding the roles of these proteins in disease and in elucidating the mechanism of fungal effector uptake into host cells.

scholarly journals Differences in the Activity of Superoxide Dismutase, Polyphenol Oxidase and Cu-Zn Content in the Fruits of Gordal and Manzanilla Olive Varieties

2002 ◽  
Vol 57 (1-2) ◽  
pp. 113-120 ◽  
Author(s):  
Dámaso Hornero-Méndez ◽  
Lourdes Gallardo-Guerrero ◽  
Manuel Jarén-Galán ◽  
María Isabel Mínguez-Mosquera
Keyword(s):  
Superoxide Dismutase ◽  
Polyphenol Oxidase ◽  
Copper Content ◽  
Redox Balance ◽  
Sod Activity ◽  
Activity Peak ◽  
Olive Variety ◽  
Zn Content ◽  
Olive Varieties ◽  
Cu And Zn

Activity of the enzymes superoxide dismutase (SOD) and polyphenol oxidase (PPO) as well as Cu-Zn content have been monitored during the thirteen weeks growth of both Gordal and Manzanilla olive variety fruits. These metalloenzymes, with Cu and Zn in the prostetic group, are involved in controlling the redox balance in the chloroplast environment. The results indicated that, under similar phenological and environmental conditions, there are periodic peaks of SOD activity in both varieties, followed by fluctuations in the copper content of the fruit. This was interpreted as a common and simultaneous response to situations of oxidative stress, and this response was more intense in the variety Gordal. The enzyme PPO showed an activity peak at start of growth and then practically disappeared. Thus, its activity cannot be correlated with situations of stress or with changes of Cu and Zn in the fruit.

scholarly journals Effect of The Date and Concentrations of The IBA on Rooting and Growth of Semi-Hard Wood Cuttings of Two Olive (Olea europaea L.) Varieties

2019 ◽  
Vol 32 ◽  
pp. 59-69
Author(s):  
Nabil M. A. Al-Imam ◽  
Qais Q. Hamid
Keyword(s):  
Landscape Design ◽  
Carbohydrate Content ◽  
Control Treatment ◽  
Subsequent Growth ◽  
College Of Agriculture ◽  
Rooted Cutting ◽  
Olea Europaea L ◽  
Rooting Ability ◽  
Olive Variety ◽  
Olive Varieties

This study was conducted in the plastic house at the Department of Horticulture and Landscape Design - College of Agriculture and Forestry - University of Mosul, Iraq. For the period from 1/2/2013 until 1/8/2013. To study the effect of three dates of cutting collection from 1st  February to 1st April monthly intervals, and soaking the cuttings in four concentrations of IBA solution 0, 2000, 3000, 4000mg.l-1 seconds on the rooting ability and subsequent growth of semi-hard wood cuttings of two olive varieties Gordal Sevillano and Tanche. The results were showed the cuttings were collected on the 1st of March resulted into the highest of rooted cutting, survival %, carbohydrate content, carbohydrate to nitrogen (C/N ratio) in the basal cuttings. Rooting increased proportionately with increasing of IBA concentrations principally the cuttings were soaked in 4000mg.l-1. Gordal Sevillano cuttings gave a significantly increase of rooting and the basal cuttings gave a significantly increased of carbohydrates content than Tanche variety. The best rooting percentage were get from interaction between Gordal Sevillano which  collected on the 1st of March treated with 4000 mg.l-1 were gave 66.67%. Highest rate of survival (80.0%) of control treatment of Tanche olive variety were taken on 1st of February. The highest content of carbohydrate (18.10) were obtained in Gordal Sevillano basal cuttings were taken on 1st of March. Higher percentage of Nitrogen (1.58%) were obtained from interaction between basal cutting of Gordal Sevillano variety. were taken on 1st of March. The highest percentage of C/N ration were got by interaction of Gordal Sevillano which collected on 1st of March.

scholarly journals Bridging the Gap: Type III Secretion Systems in Plant-Beneficial Bacteria

2022 ◽  
Vol 10 (1) ◽  
pp. 187
Author(s):  
Antoine Zboralski ◽  
Adrien Biessy ◽  
Martin Filion
Keyword(s):  
Type Iii Secretion ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Effector Proteins ◽  
Secretion Systems ◽  
Beneficial Bacteria ◽  
Living Plant ◽  
Pseudomonas Spp ◽  
Type Iii ◽  
Type Iii Secretion Systems

Type III secretion systems (T3SSs) are bacterial membrane-embedded nanomachines translocating effector proteins into the cytoplasm of eukaryotic cells. They have been intensively studied for their important roles in animal and plant bacterial diseases. Over the past two decades, genome sequencing has unveiled their ubiquitous distribution in many taxa of Gram-negative bacteria, including plant-beneficial ones. Here, we discuss the distribution and functions of the T3SS in two agronomically important bacterial groups: the symbiotic nodule-forming nitrogen-fixing rhizobia and the free-living plant-beneficial Pseudomonas spp. In legume-rhizobia symbiosis, T3SSs and their cognate effectors play important roles, including the modulation of the plant immune response and the initiation of the nodulation process in some cases. In plant-beneficial Pseudomonas spp., the roles of T3SSs are not fully understood, but pertain to plant immunity suppression, biocontrol against eukaryotic plant pathogens, mycorrhization facilitation, and possibly resistance against protist predation. The diversity of T3SSs in plant-beneficial bacteria points to their important roles in multifarious interkingdom interactions in the rhizosphere. We argue that the gap in research on T3SSs in plant-beneficial bacteria must be bridged to better understand bacteria/eukaryotes rhizosphere interactions and to support the development of efficient plant-growth promoting microbial inoculants.

scholarly journals Experimental Nets for a Protection System against the Vectors of Xylella fastidiosa Wells et al.

Agriculture ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 32 ◽  
Author(s):  
Sergio Castellano ◽  
Antonella Di Palma ◽  
Giacinto Germinara ◽  
Marco Lippolis ◽  
Giuseppe Starace ◽  
...  
Keyword(s):  
Field Experiments ◽  
Xylella Fastidiosa ◽  
Mesh Size ◽  
Olive Tree ◽  
Cross Sectional ◽  
Wooden Frame ◽  
Field Nursery ◽  
Pass Through ◽  
Laboratory Bioassays ◽  
Meadow Spittlebug

The effectiveness of experimental nets in preventing the access of adult meadow spittlebug Philaenus spumarius L., the main vector of Xylella fastidiosa Wells et al. subspecies pauca, sequence type (ST) 53, in olive tree nurseries and orchards was evaluated. To optimize the net design, mesh size, kind of fabric, thread typology, and radiometric properties, six nets with different mesh sizes and kinds of fabric were evaluated in laboratory and in field experiments. Laboratory bioassays evaluating the capability of adult spittlebugs to pass through nets with different mesh sizes (1.2, 1.8, 2.4 mm) showed that all nets with a mesh size equal to or lower than 2.4 mm prevented insect crossing. These results were confirmed in field conditions using an experimental net box apparatus. Further laboratory tests showed a positive correlation between porosity and radiometric properties of the nets. Three prototypes of thermally stabilized flat woven nets made of circular cross-sectional yarns, knitted net with strips, and knitted nets made of yarns were tested after the evaluation of their potential usability in terms of porosity stability. The knitted net features were found to be the most suitable. The net transmissivity of the total and direct component of solar radiation in the photosynthetically active radiation and the infrared ranges increased with the net porosity. A prism-shaped wooden frame with a triangular base covered with the knitted net with a 2.4 mm mesh confirmed the insect’s capability of reaching considerable heights, up to 2.85 m. Hence, based on our results, the monowire knitted net with a 2.4 mm mesh can be used in open field nursery and olive orchards to prevent the access of P. spumarius adults and to shield the openings of greenhouse nurseries.

scholarly journals Hyperspectral Reflectance as a Basis to Discriminate Olive Varieties—A Tool for Sustainable Crop Management

2020 ◽  
Vol 12 (7) ◽  
pp. 3059
Author(s):  
Luis Gomes ◽  
Tânia Nobre ◽  
Adélia Sousa ◽  
Fernando Rei ◽  
Nuno Guiomar
Keyword(s):  
Olive Oil ◽  
Environmental Sustainability ◽  
Rural Areas ◽  
Agricultural Land ◽  
Value Added ◽  
Variety Identification ◽  
Olive Variety ◽  
Mediterranean Countries ◽  
Olive Groves ◽  
Olive Varieties

Worldwide sustainable development is threatened by current agricultural land change trends, particularly by the increasing rural farmland abandonment and agricultural intensification phenomena. In Mediterranean countries, these processes are affecting especially traditional olive groves with enormous socio-economic costs to rural areas, endangering environmental sustainability and biodiversity. Traditional olive groves abandonment and intensification are clearly related to the reduction of olive oil production income, leading to reduced economic viability. Most promising strategies to boost traditional groves competitiveness—such as olive oil differentiation through adoption of protected denomination of origin labels and development of value-added olive products—rely on knowledge of the olive varieties and its specific properties that confer their uniqueness and authenticity. Given the lack of information about olive varieties on traditional groves, a feasible and inexpensive method of variety identification is required. We analyzed leaf spectral information of ten Portuguese olive varieties with a powerful data-mining approach in order to verify the ability of satellite’s hyperspectral sensors to provide an accurate olive variety identification. Our results show that these olive varieties are distinguishable by leaf reflectance information and suggest that even satellite open-source data could be used to map them. Additional advantages of olive varieties mapping were further discussed.

scholarly journals To Plant or Not to Plant, That Is the Question: Reforestation vs. Natural Regeneration of Hurricane-Disturbed Mangrove Forests in Guanaja (Honduras)

Forests ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1068
Author(s):  
Thomas Fickert
Keyword(s):  
Time Lag ◽  
Rhizophora Mangle ◽  
Ground Cover ◽  
Lessons Learned ◽  
Mangrove Forests ◽  
Hurricane Mitch ◽  
Living Plant ◽  
Line Transects ◽  
Almost All ◽  
Regeneration Processes

Background and Objectives: Mangrove forests offer many essential ecosystem services, including the protection of (sub)tropical coastlines, their inhabitants, and the infrastructure from severe storms and tsunamis. However, mangroves themselves suffer severely from such phenomena. After such events, reforestation efforts are widely undertaken to facilitate the recovery of the mangroves. Many of these laborious activities, however, fail for a number of reasons. Material and Methods: In October 1998, the Honduran Island of Guanaja was severely hit by Hurricane Mitch, and, after the storm, almost all of the mangrove forests (97%) were rated as dead. Seven years after Mitch, a longterm survey on the regeneration of the mangroves started. Field samplings in six variably disturbed mangrove zones was conducted in 2005, 2009, and 2016. Along permanent line-transects, all living plant species were recorded for statistical analyses and for quantifying progress. In this paper, the focus is on the three most severely hit areas. In two of them, planting efforts were carried out while the third one was left to regenerate naturally. This setting allowed a direct comparison between natural and human-assisted regeneration processes under otherwise similar conditions and equally severe previous disturbance. Results: Reforestation measures were characterized by high mortality rates of Rhizophora mangle L. propagules planted predominantly. Some, however, surely survived and might have contributed to regeneration after the disturbance. In 2016, roughly two decades after Hurricane Mitch, low-growing Rhizophora mangle forests, with high ground cover, were found. Surprisingly, the area without any planting also witnessed similar mangrove rejuvenation in the same period. Conclusion: Findings on the recovering mangroves in Guanaja confirm the lessons learned from other mangrove rehabilitation measures: planting mostly fails and commonly does not accelerate the revegetation of disturbed forests. In naturally regenerating forests, recolonization may occur after a certain time-lag only if few diaspore sources survived in the surrounding; as soon as established mangrove plants bear propagules, a quick return to viable forests takes place, proving the high resilience of these coastal ecosystems.

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