Mountain Research Center

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Comparing the response of Citrus ×limon and Citrus ×sinensis to Trioza erytreae infestation using a proteomic approach

Publication . Magalhães, Tomás; Dandlen, Susana; L, Anjos; Power, Deborah; Pereira, José Alberto; Duarte, Amilcar; Marques, Natália

Citrus production is on high alert because of the devastating disease Huanglongbing (HLB), caused by the bacteria Candidatus Liberibacter spp.. With no viable treatment, current management practices rely on the control of its vectors, such as the African citrus psyllid,Trioza erytreae (Del Guercio 1918), which is already in the Mediterranean region (Portugal and north of Spain). This vector develops better in some citrus hosts, with Citrus ×limon described as the preferred host. To better understand the molecular response of citrus hosts to the psyllid, the phloem proteome of lemon (Citrus ×limon) and orange (Citrus ×sinensis) plants infested with T. erytreae was compared with equivalent non infested plants. Infestation was established with isolated plants by exposing them to 10 T. erytreae adults. Nymphs of T. erytreae at the 4-5th instar stage were removed from plants and infested leaf phloem was extracted. In control plants phloem was extracted from leaves of a similar size and developmental stage. The experiment was done under controlled conditions of temperature, light and humidity. Phloem was analyzed by nanoLC-MS/MS. A total of 48 and 1265 differentially abundant proteins (DAP) were identified in lemon and orange plants, respectively, with 18 proteins common to both species. The topmost enriched GO terms retrieved for upregulated proteins in lemon plants were assigned to organic acid and cellular amino acid metabolic processes. The topmost enriched GO terms in orange plants included organonitrogen compound metabolic process, cellular component assembly, establishment of protein localization, while downregulated terms were associated with carbohydrate metabolic process. This study revealed that T. erytreae infestation promoted distinct modifications in the phloem proteome of lemon and orange plants. This work is part of a group of studies that focus on this insect-plant interaction that aims for more informed and improved T. erytreae control.

2022-11-08Conference object

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Electrical impedance spectroscopy for potassium content analysis and botanical origin identification of honey

Publication . Elamine, Youssef; INÁCIO, PEDRO; Miguel, Maria da Graça; Carlier, Jorge; Costa, Maria Clara; Estevinho, Leticia M.; Gomes, Henrique L.

Minerals are reported to dominate the electrical properties of honey and indicate its botanical and geographical origins. In this study, Electrochemical Impedance Spectroscopy (EIS) was used to assess the relation between mineral elements, electrical properties and botanical origin using three honey varieties - Citrus sp., Eucalyptus sp., and Erica sp. These varieties are identified through pollen analysis and market labelling. Flame atomic absorption and emission spectroscopies were used to quantify the concentrations of eight elements (potassium, sodium, calcium, magnesium, manganese, zinc, copper, and iron). Among all the mineral elements, potassium showed a consistent correlation with impedance. The potassium estimation in honey and standard solutions (calibration curve) had similar sensitivities of 153.43 nF/mM and 132.68 nF/mM, respectively. Additionally, the analysis revealed that potassium dominates the mineral composition, with the other species present in minimal quantities. The EIS technique showed high sensitivity to potassium and other ionisable species, making it possible to classify the botanical origin of these three honey types. The EIS technique proved to be both time and cost effective, yielding a classification rate higher than that achieved by analysing mineral composition.

2024-09Journal article

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Protective properties of the edible halophyte Carpobrotus edulis (L.) N.E.Br. towards neoformed food contaminants-related oxidative stress and genotoxicity

Publication . Oliveira, Daniela; Hayrapetyan, Ruzanna; Dias, Maria Inês; Barros, Lillian; Séverin, Isabelle; Custódio, Luísa; Chagnon, Marie-Christine; Oliveira, Rui

Carpobrotus edulis (L.) N.E.Br. is an edible halophyte native to South Africa, where it has been traditionally consumed as food, revealing its nutritional value, and used in the treatment of human diseases probably due to the accumulation of bioactive compounds such as polyphenols. These compounds have potential to display valuable biological activities that could bring several benefits to the human being, including the mitigation of toxicity induced by food contaminants. Therefore, this study investigated biological activities with healthpromoting potential of a C. edulis ethanol extract (CEE), such as antioxidant, antigenotoxic, and antimutagenic. CEE was shown by LC-DAD-ESI/MSn to be composed of 16 polyphenols. The extract exhibited antioxidant properties by protecting Saccharomyces cerevisiae viability and improving the redox state of HepG2 cells under oxidative stress. Antigenotoxicity of CEE against H2O2-induced oxidative damage was detected in HepG2 and Caco-2 cells by comet assay and subsequently observed in the dominant deletion assay in S. cerevisiae. Antigenotoxicity and antimutagenicity of CEE towards the neoformed contaminant benzo[a]pyrene was found in HepG2 and Caco-2 cells by comet assay and in Salmonella typhimurium using the Ames test, respectively. The disclosed antigenotoxic and antimutagenic properties of C. edulis further advance its potential for application in food and nutraceutical industries for health benefits.

2024-10Journal article

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Developing epidemiological preparedness for a plant disease invasion: modelling citrus huánglóngbìng in the European Union

Publication . Ellis, John; Lázaro, Elena; Zarcos Duarte, Beatriz; Abranches de Magalhães, Tomás Thormann; Duarte, Amilcar; Benhadi‐Marín, Jacinto; Pereira, José Alberto; Vicent, Antonio; Parnell, Stephen; Cunniffe, Nik J.

Societal Impact Statement Huanglongbing (HLB) is a bacterial disease of citrus that has significantly impacted Brazil and the United States, although citrus production in the Mediterranean Basin remains unaffected. By developing a mathematical model of spread in Spain, we tested surveillance and control strategies before any future HLB entry in the EU. We found while some citrus production might be maintained by roguing, this requires extensive surveillance and significant chemical control, perhaps also including testing of psyllids (which spread the pathogen) for bacterial DNA. Our work highlights the key importance of early detection (including asymptomatic infection) and vector control for HLB management. Summary Huanglongbing (HLB; citrus greening) is the most damaging disease of citrus worldwide. While citrus production in the United States and Brazil have been affected for decades, HLB has not been reported in the European Union (EU). However, a HLB vector, the African citrus psyllid, is already in Portugal and Spain. In 2023, the major vector, the Asian citrus psyllid, was first reported in Cyprus. We develop a landscape-scale, epidemiological model, accounting for heterogeneous citrus cultivation and vector dispersal, as well as climate and disease management. We use our model to predict HLB dynamics for an epidemic vectored by the African citrus psyllid in high-density citrus areas in Spain, assessing detection and control strategies. Without disease management, we predict large areas infected within 10-20 years. Even with significant visual surveillance, any epidemic will be widespread on first detection, making eradication unlikely. Nevertheless, increased inspection and roguing following first detection, particularly if coupled with intensive insecticide use, could sustain some citriculture for a decade or more, albeit with reduced production. However, effective control may require chemical application rates and/or active substances no longer authorised in the EU. Strategies targeting asymptomatic infection will be more successful. Detection of bacteriliferous vectors-sometimes possible long before plants show symptoms-could reduce lags before disease management commences. If detection of HLB-positive vectors were followed by intensive insecticide sprays, this may greatly improve outcomes. Our work highlights modelling as a key component of developing epidemiological preparedness for a pathogen invasion that is, at least somewhat, predictable in advance.

2025-02-24Journal article

Open access