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- Can bicarbonate enhance the performance of carob seedlings grown in nutrient solutions with different Fe concentrations?Publication . Gama, Florinda; Correia, Pedro José; Saavedra, T.; Dandlen, Susana; de Varennes, Amarilis; Nolasco, Gustavo; Pestana, MaribelaThe aim of this work was to assess the effect of bicarbonate (Bic) ion on the nutritional status and performance of carob-tree seedlings, a species that normally grows in calcareous soil without exhibiting iron chlorosis symptoms. Seedlings were previously grown in nutrient solution with a small concentration of Fe (0.5-1 mu M) to induce a moderate chlorosis. Afterwards, two experiments were established: in experiment 1, plants were grown for 21 days in the following treatments: Fe deficiency (Fe0), 0.5 mu M Fe, 5 mu M Fe, and 5 mu M Fe plus calcium carbonate (CaCO3). After assessing these results, a second experiment was conducted for 91 days, with the following treatments: Fe0, 1 mu M Fe, 40 mu M Fe and 40 mu M Fe plus CaCO3 and sodium bicarbonate (NaHCO3). Chlorophyll of young leaves, biomass and mineral composition of leaves, stems and roots were assessed in both experiments. The ferric chelate reductase root activity (FC-R) and the genetic expression of calmodulin-regulated Ca2+-ATPase pump (ACA gene) were evaluated in experiment 2. Fe-deficient plants exhibited reduced growth and enhanced macronutrients in leaves. Root micronutrient homeostasis changed as an adaptive mechanism in carob. The addition of bicarbonate did not aggravate Fe chlorosis, as leaf chlorophyll increased significantly. Root FC-R activity and ACA gene expression was not enhanced under Fe deficiency induced by bicarbonate (Fe40 + BicNa) which suggest a positive effect of bicarbonate in the metabolism of this crop. Nevertheless, small Fe concentrations (Fe1) induced a higher ACA gene expression thus indicating some stress response signalling.
- Antibacterial activity of propolis extracts from the south of PortugalPublication . Oliveira, Ana; Ferreira, Ana Luisa; Nunes, Susana; Dandlen, Susana; Miguel, Maria; Faleiro, Maria LeonorTo examine the antibacterial activity of diverse extracts of propolis harvested at winter and spring from several locations of Algarve, Portugal, against Gram-negative and Gram-positive bacteria was the main goal of the present work. For such, the antibacterial activity was determined by agar diffusion. The results showed that all tested bacterial strains showed susceptibility to diluted propolis extracts and in a dose-dependent manner. Two propolis samples collected at springtime showed higher antibacterial activity, in comparison with samples harvested at wintertime. Ethanolic and methanolic extracts have a very similar activity (P<0.05). Helicobacter pylori strains J99 and 26695 were the most susceptible strains to the tested extracts (33.67 +/- 2.52 mm and 35.67 +/- 0.58mm, respectively). This study constitutes the first approach of the biological activities of Portuguese propolis from the Algarve region and evidences its potential use to combat bacterial infections, in particular against the gastric pathogen H. pylori.
- Silencing of FRO1 gene affects iron homeostasis and nutrient balance in tomato plantsPublication . Gama, Florinda; Saavedra, Teresa; Dandlen, Susana; García‐Caparrós, Pedro; de Varennes, Amarilis; Nolasco, Gustavo; Correia, Pedro José; Pestana, MaribelaBackgroundIron chlorosis is an abiotic stress of worldwide importance affecting several agronomic crops. It is important to understand how plants maintain nutrient homeostasis under Fe deficiency and recovery. AimsWe used the virus-induced gene silencing (VIGS) method to elucidate the role of the FRO1 gene in tomato plants and identify the impact on regulation of the root ferric-chelate reductase (FCR) activity and nutritional homeostasis. MethodsTomato plantlets cv. "Cherry" were transferred into half-strength Hoagland's nutrient solution containing 0.5 & mu;M of Fe (Fe0.5). In phase I, two treatments were established: control (Fe0.5) plants and VIGS-0.5 plants corresponding to plants with the FRO1 gene silenced. In phase II, plants from Fe0.5 and VIGS-0.5 were transferred to new nutrient solution and then grown for a further 14 days under 0 and 10 & mu;M of Fe (as 0.5 & mu;M would not be enough for the larger plants during phase II). Therefore, four treatments were imposed: Fe0, Fe10, VIGS-0, and VIGS-10. ResultsVIGS-0.5 plants had significantly lower chlorophyll (Chl) and root FCR activity compared to the respective non-silenced plants and retained more Cu and Zn in the roots at the expense of stems (Cu) or young leaves (Zn). Iron concentration in roots and stems decreased in FRO1 gene-silenced plants, compared to control plants, but the allocation to different organs was similar in both treatments. ConclusionsThere was a partial recovery of leaf Chl in the VIGS-10 plants and a higher concentration of Fe in all organs. In contrast, the allocation of Cu to roots decreased in the VIGS-10 plants.
- Myrtus communis essential oils: insecticidal, antioxidant and antimicrobial activities: a reviewPublication . Hennia, Aicha; Nemmiche, Said; Dandlen, Susana; Miguel, Maria GracaMyrtle (Myrtus communis L.) is a wild aromatic plant that laboratorial works have demonstrated the insecticidal, antioxidant, anti-inflammatory and antimicrobial activities of myrtle essential oils (EOs). The chemical composition may change according to several factors; nevertheless, it was constant in practically all EOs the presence of 1,8-cineole and α-pinene, as main components (>5%). The biological activities, generally low or moderate depended on the organism (insecticidal) and microorganism and on the chemical composition. Generally, the contribution of the components on the biological activities was not determined; nevertheless, they were generally attributed to the presence of the main components (1,8-cineole, α-pinene, eugenol, methyleugenol, myrtenyl acetate, among other components depending on the property). The antioxidant activity of myrtle oil was predominantly determined in cell-free methods, though very few works also used cell model methods. In all cases, the activities were also low to moderate due to the absence of phenol compounds.
- Silencing of the FRO1 gene and its effects on iron partition in Nicotiana benthamianaPublication . Gama, Florinda; Saavedra, Teresa; Dandlen, Susana; de Varennes, Amarilis; Correia, Pedro José; Pestana, Maribela; Nolasco, GustavoTo evaluate the dynamic role of the ferric-chelate reductase enzyme (FCR) and to identify possible pathways of regulation of its activity in different plant organs an investigation was conducted by virus induced gene silencing (VIGS) using tobacco rattle virus (TRV) to silence the ferric reductase oxidase gene (FROI) that encodes the FCR enzyme. Half of Nicotiana benthamiana plants received the VIGS vector and the rest remained as control. Four treatments were imposed: two levels of Fe in the nutrient solution (0 or 2.5 mu M of Fe), each one with silenced or non-silenced (VIGS-0; VIGS-2.5) plants. Plants grown without iron (0; VIGS-0) developed typical symptoms of iron deficiency in the youngest leaves. To prove that FROI silencing had occurred, resupply of Fe (R) was done by adding 2.5 mu M of Fe to the nutrient solution in a subset of chlorotic plants (0-R; VIGS-R). Twelve days after resupply, 0-R plants had recovered from Fe deficiency while plants containing the VIGS vector (VIGS-R) remained chlorotic and both FRO1 gene expression and FCR activity were considerably reduced, consequently preventing Fe uptake. With the VIGS technique we were able to silence the FRO1 gene in N. benthamiana and point out its importance in chlorophyll synthesis and Fe partition. (C) 2017 Elsevier Masson SAS. All rights reserved.
- Correction to: Can bicarbonate enhance the performance of carob seedlings grown in nutrient solutions with different Fe concentrations?Publication . Gama, Florinda; Correia, Pedro; Saavedra, Teresa; Dandlen, Susana; de Varennes, Amarilis; Nolasco, Gustavo; Pestana, MaribelaCorrection to: Journal of Soil Science and Plant Nutrition https://doi.org/10.1007/s42729-019-00100-4
- Quick decline and stem pitting Citrus tristeza virus isolates induce a distinct metabolomic profile and antioxidant enzyme activity in the phloem sap of two Citrus speciesPublication . Dandlen, Susana; Da Silva, José Paulo; Miguel, Maria Graca; Duarte, Amilcar; Power, Deborah; Marques, NatáliaSusceptibility to the severe Citrus tristeza virus (CTV), T36, is higher for Citrus macrophylla (CM) than for C. aurantium (CA). How host-virus interactions are reflected in host physiology is largely unknown. In this study, the profile of metabolites and the antioxidant activity in the phloem sap of healthy and infected CA and CM plants were evaluated. The phloem sap of quick decline (T36) and stem pitting (T318A) infected citrus, and control plants was collected by centrifugation, and the enzymes and metabolites analyzed. The activity of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), in infected plants increased significantly in CM and decreased in CA, compared to the healthy controls. Using LC-HRMS2 a metabolic profile rich in secondary metabolites was assigned to healthy CA, compared to healthy CM. CTV infection of CA caused a drastic reduction in secondary metabolites, but not in CM. In conclusion, CA and CM have a different response to severe CTV isolates and we propose that the low susceptibility of CA to T36 may be related to the interaction of the virus with the host’s metabolism, which reduces significantly the synthesis of flavonoids and antioxidant enzyme activity.
- Comparing the response of Citrus ×limon and Citrus ×sinensis to Trioza erytreae infestation using a proteomic approachPublication . Magalhães, Tomás; Dandlen, Susana; L, Anjos; Power, Deborah; Pereira, José Alberto; Duarte, Amilcar; Marques, NatáliaCitrus 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.