Browsing by Author "de Varennes, Amarilis"
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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.
- Changes in nutritional homeostasis of Poncirus trifoliata and Ceratonia siliquaas a response to different iron levels in nutrient solutionPublication . Correia, Pedro José; de Varennes, Amarilis; Gama, Florinda; Saavedra, Teresa; Pestana, MaribelaIron (Fe) deficiency is a nutritional disorder in plants. Poncirus trifoliata is susceptible to Fe deficiency, but symptoms of Fe deficiency are rare in Ceratonia siliqua, a slow-growing species. Specimens of the two species were grown in nutrient solutions containing three Fe concentrations: without Fe (0 mM), 1 mM Fe, and either 10 mM Fe (for Ceratonia) or 40 mM Fe (for P. trifoliata). Growth, the degree of chlorosis, the plant mineral composition, and the activity of the root ferric chelate-reductase (FCR) were assessed. Ceratonia plants exposed to 1 mM Fe were efficient at using Fe in the synthesis of chlorophyll. The activity of FCR was enhanced in the total absence of Fe. In Poncirus a low activity of the FCR was observed in plants with no Fe. The balance between micronutrients in the Ceratonia roots was not affected with 1 mM Fe compared with the higher Fe concentration treatments.
- 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
- Effects of foliar application of organic acids on strawberry plantsPublication . Saavedra, Teresa; Gama, Florinda; Rodrigues, Maria Joao; Abadía, Javier; de Varennes, Amarilis; Pestana, Maribela; Da Silva, José Paulo; Correia, Pedro JoséThe large economic costs and environmental impacts of iron-chelate treatments has led to the search for alter-native methods and compounds to control iron (Fe) deficiency chlorosis. Strawberry plants (Fragaria x ananassa) were grown in Hoagland's nutrient solution in a greenhouse with two levels of Fe: 0 and 10 mu M Fe(III)-EDDHA. After 20 days, plants growing without Fe showed typical symptoms of Fe deficiency chlorosis in young leaves. Then, the adaxial and abaxial sides of one mature or one young leaf in each plant were brushed with 10 mM malic (MA), citric (CA) or succinic (SA) acids. Eight applications were done over a two-week period. At the end of the experiment, the newly emerged (therefore untreated), young and mature leaves were sampled for nutritional and metabolomic analysis, to assess the effectiveness of treatments. Leaf regreening was monitored using a SPAD-502 apparatus, and the activity of the ferric chelate-reductase activity (FCR) was measured using root tips. Iron deficiency negatively affected biomass and leaf chlorophyll but did not increase FCR activity. Application of succinic acid alleviated the decrease in chlorophyll observed in other treatments, and the overall nutritional balance in the plant was also changed. The concentrations of two quinic acid derivatives increased under Fe deficiency and decreased in plants treated with succinic acid, and thus they are proposed as Fe stress markers. Data suggest that foliage treatments with carboxylates may be, in some cases, environmentally friendly alter-natives to Fe(III)-chelates. The importance of Fe mobilization pathways in the formulation of new fertilizers is also discussed.
- A novel plant extract as a biostimulant to recover strawberry plants from iron chlorosisPublication . Saavedra, Teresa; Gama, Florinda; Correia, P.J.; Da Silva, José Paulo; Miguel, Maria da Graça; de Varennes, Amarilis; Pestana, MaribelaThe traditional agricultural production systems are evolving more towardorganic, sustainable or environmental friendly systems and products; how-ever, it is important to keep the yield and the quality of crops. The aim ofthis work was to evaluate the recovery of iron deficient strawberry plantsby foliar spray, using a gramineous plants extract (GE). Bare-root trans-plants of strawberry (Fragaria ananassaDuch. cv“Diamond”) were grownin a Hoagland’s nutrient solution with iron (Fe10) or without (Fe0). Forty-two days after Fe deprivation, plants grown without iron became chloroticand GE was applied. Three foliar applications were done, once per weekand the regreening was monitored using a SPAD apparatus. After twoapplications, a rapid but transient regreening was detected in youngleaves. Nevertheless, biomass and root/shoot ratio of recovered plants (GEtreatment) were similar to chlorotic plants (Fe0 treatment). Phosphorous,Mn and Fe contents were higher in crowns of GE plants at the end of theexperiment (67 days). The concentration of organic acids and ferric chela-te–reductase (FC-R) activity was also significantly higher in GE treatment. Itis possible that the high chelating capacity of the extract was responsible or the Fe internal transport and use.
- 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.
- 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.
- The memory of iron stress in strawberry plantsPublication . Gama, Florinda; Saavedra, Teresa; Da Silva, José Paulo; Miguel, Maria; de Varennes, Amarilis; Correia, José Pedro; Pestana, MaribelaTo provide information towards optimization of strategies to treat Fe deficiency, experiments were conducted to study the responses of Fe-deficient plants to the resupply of Fe. Strawberry (Fragaria x ananassa Duch.) was used as model plant. Bare-root transplants of strawberry (cv. 'Diamante') were grown for 42 days in Hoagland's nutrient solutions without Fe (Fe0) and containing 10 mu M of Fe as Fe-EDDHA (control, Fe10). For plants under Fe0 the total chlorophyll concentration of young leaves decreased progressively on time, showing the typical symptoms of iron chlorosis. After 35 days the Fe concentration was 6% of that observed for plants growing under Fe10. Half of plants growing under Fe0 were then Fe-resupplied by adding 10 mu M of Fe to the Fe0 nutrient solution (FeR). Full Chlorophyll recovery of young leaves took place within 12 days. Root ferric chelate-reductase activity (FCR) and succinic and citric acid concentrations increased in FeR plants. Fe partition revealed that FeR plants expressively accumulated this nutrient in the crown and flowers. This observation can be due to a passive deactivation mechanism of the FCR activity, associated with continuous synthesis of succinic and citric acids at root level, and consequent greater uptake of Fe. (C) 2016 Elsevier Masson SAS. All rights reserved.