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Centre for the Research and Technology of Agro-Environmental and Biological Sciences
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Histological analysis of Xylella fastidiosa infection in Quercus pyrenaica in Northern Portugal
Publication . Loureiro, Talita; Gonçalves, Berta; Serra, Luís; Martins, Ângela; Cortez, Isabel; Poeta, Patrícia; LAQV@REQUIMTE; AIMS Press - American Institute of Mathematical Sciences
Quercus pyrenaica Willd thrives in the intermediate zone between the Mediterranean sclerophyllous and the temperate deciduous forest. In December 2022, the presence of the bacteria Xylella fastidiosa (Xf) was confirmed in samples collected from a Quercus pyrenaica located in Sabrosa, Vila Real, Portugal. Following Xf infection, the transport of water and nutrients is hindered due to the occlusion of xylem vessels. This loss of hydraulic conductivity may lead to vessel blockage and subsequent embolism formation. The objective of this study was to investigate the interaction between Xf and Quercus pyrenaica tissues, as well as the mechanism by which the bacteria can spread through the plant’s xylem vessels, ultimately resulting in the formation of vascular plugs. At the time of the sample collection (10 months post-detection), symptoms of Bacterial Leaf Scorch (BLS) began to appear. Examination of xylem vessels using both light and scanning electron microscopy (SEM) revealed the presence of various types of occlusions, predominantly tyloses. Additionally, fibrillar networks, gums, starch grains, and crystals were observed. The stem vessels exhibited significantly more occlusions compared to the leaves. Furthermore, individual bacterial cells were observed to be attached to the vessel wall. This implies that occlusions were primarily induced by tyloses and gums as a defensive response to the invasion of vascular pathogens, in addition to the pathogen itself. This study highlights the presence of starch grains in stems, which may function as a refilling mechanism, thereby preventing the loss of hydraulic conductivity in plants and potentially acting as a means to entrap the bacteria. These mechanisms exemplify the constitutive defense systems of the plant against Xf. Understanding the interaction between Xylella fastidiosa and Quercus pyrenaica is crucial, given that the latter species occupies nearly 95% of the natural distribution area of Portugal.
Platanus hybrida’s Phenolic Profile, Antioxidant Power, and Antibacterial Activity against Methicillin-Resistant Staphylococcus aureus (MRSA)
Publication . Ribeiro, Jessica; Silva, Vanessa; Aires, Alfredo; Carvalho, Rosa; Barros, Lillian; Gaivão, Isabel; Igrejas, Gilberto; Poeta, Patrícia; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Methicillin-resistant S. aureus (MRSA) are a threat to public health as they frequently reveal a multidrug-resistant pattern. Researchers all over the world are on an urgent hunt for new treatments to help fight infections before antibiotics become obsolete, and some natural alternatives, such as polyphenols, have already exhibited therapeutic properties. Therefore, this study aimed to determine the phenolic profile, antioxidant capacity, and antimicrobial activity against MRSA of the leaf, fruit, and stem bark extracts of Platanus hybrida. The polyphenols were extracted with a water/ethanol (20:80) mixture and the methodology included HPLC-DAD, DPPH, FRAP, and CuPRAC. To address this issue from a One Health perspective, the Kirby–Bauer disc diffusion method was performed against nine MRSA strains from three different sources (livestock, wild animals, and humans). Fourteen phenolics were identified and the leaf extract showed the highest phenolic content, followed by the fruit extract. The leaf extract also showed the highest antioxidant capacity while the fruit extract had the lowest antioxidant capacity. Both leaf and fruit extracts inhibited the growth of strains from all sources, while the stem bark extract did not inhibit the growth of human strains. This work highlights the complex chemical composition and the antioxidative and antimicrobial potential of extracts derived from P. hydrida.
Vibrio spp.
Publication . Sampaio, Ana; Silva, Vanessa; Poeta, Patrícia; Aonofriesei, Florin; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Vibrios are ubiquitous bacteria in aquatic systems, especially marine ones, and belong to the Gammaproteobacteria class, the most diverse class of Gram-negative bacteria. The main objective of this review is to update the information regarding the ecology of Vibrio species, and contribute to the discussion of their potential risk in a changing environment. As heterotrophic organisms, Vibrio spp. live freely in aquatic environments, from marine depths to the surface of the water column, and frequently may be associated with micro- and macroalgae, invertebrates, and vertebrates such as fish, or live in symbiosis. Some Vibrio spp. are pathogenic to humans and animals, and there is evidence that infections caused by vibrios are increasing in the world. This rise may be related to global changes in human behavior (increases in tourism, maritime traffic, consumption of seafood, aquaculture production, water demand, pollution), and temperature. Most likely in the future, Vibrio spp. in water and in seafood will be monitored in order to safeguard human and animal health. Regulators of the microbiological quality of water (marine and freshwater) and food for human and animal consumption, professionals involved in marine and freshwater production chains, consumers and users of aquatic resources, and health professionals will be challenged to anticipate and mitigate new risks.
Xylella fastidiosa Dispersion on Vegetal Hosts in Demarcated Zones in the North Region of Portugal
Publication . Loureiro, Talita; Serra, Luís; Martins, Ângela; Cortez, Isabel; Poeta, Patrícia; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
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.
Irradiance level and elevation shape the soil microbiome communities of Coffea arabica L.
Publication . Tapaça, Inocência da Piedade E.; Obieze, Chinedu C.; Pereira, Gilberto V.de Melo; Fangueiro, David; Coutinho, João; Fraga, Irene; Partelli, Fábio L.; Ramalho, José C.; Marques, Isabel; Ribeiro-Barros, Ana I.; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; Faculdade de Ciências e Tecnologia (FCT); BioMed Central (BMC)
Background: The nexus plant-microbe-environment is essential to understand the ecosystem processes shaping plant health and fitness. Within this triangle, soils and associated microflora are among the key ecosystem’s drivers, underpinning plant productivity and evolution. In this study, we conducted a comprehensive analysis (physicochemical properties, enzyme activities, and taxonomic diversity) of soils under the canopy projection of Coffea arabica trees along a gradient of elevation (600, 800, and 900 m) and shade (0, 50, 100%). Results: While shade had no influence on most parameters, altitude shaped the dynamics of microbial communities. Available phosphorus, soil organic carbon, and nitrate were significantly higher at 800 m, likely due to the higher activities of β-glucosidase and phosphatases at this altitude. Microbial biomass (carbon and nitrogen) and moisture were significantly higher at 600 and 900 m, which might be attributed to the abundance and richness of soil microorganisms. Indeed, metabarcoding analysis revealed a complex pattern of microbial consortia (bacteria, archaea, fungi) at the three altitudes, with the lowest index of richness recorded at 800 m. The highest number of Amplicon Sequence Variants was observed in bacteria, whose functional analysis revealed distinct metabolic adaptations across different altitudes. At 900 m, the main functional attributes favored the responses to environmental stimuli and microbial interactions; at 800 m, the predominant metabolic pathways were related to organic matter, fermentation, and bioremediation; and at the lower 600 m, the pathways shifted towards the breakdown of plant-derived compounds (e.g. geraniol, limonene, and pinene degradation). Conclusion: Overall, the results indicate a higher effectiveness of the microbial consortium at 800 m, which might result in better nutrient cycling. The study highlights the importance of canopy shade species and elevation for the composition of microbial consortia in C. arabica, unveiling ecological functions beyond plant health, with implications for bio-based solutions and biotechnology.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04033/2020