IRON TRAFFICKING AND SIGNALLING IN STRAWBERRY PLANTS

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A novel plant extract as a biostimulant to recover strawberry plants from iron chlorosis

Publication . Saavedra, Teresa; Gama, Florinda; Correia, P.J.; Da Silva, José Paulo; Miguel, Maria da Graça; de Varennes, Amarilis; Pestana, Maribela

The 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.

2020Journal article

Restricted access

The memory of iron stress in strawberry plants

Publication . Gama, Florinda; Saavedra, Teresa; Da Silva, José Paulo; Miguel, Maria; de Varennes, Amarilis; Correia, José Pedro; Pestana, Maribela

To 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.

2016-07Journal article

Restricted access

Responses of tomato (Solanum lycopersicum L.) plants to iron deficiency in the root zone

Publication . Jiménez, María Rocío; Casanova, Laura; Saavedra, Teresa; Gama, Florinda; Suárez, María Paz; Correia, Pedro José; Pestana, Maribela

Iron deficiency induces a yellowing in the aerial part of plants, known as iron chlorosis, and reduces the growth, yield, and quality of the fruits. Understanding plant response to iron deficiency is essential for agronomic management. This study decoded the temporal response of tomato plants (Solanum lycopersicum L.) to iron deficiency by quantifying different vegetative parameters. Subapical root swelling in the first 2.0 mm and several shoot and root growth parameters were measured in plants grown in a nutrient solution with and without Fe, on different dates designated as days after transplantation (DAT). Correlations between the total chlorophyll concentration in young leaves and 22 morphological and physiological parameters were also calculated. The plants grown in the absence of Fe had a higher number of secondary roots at 3 DAT, compared to control plants. On the same date, subapical root swelling was also observed, particularly at 1.5 and 2.0 mm from the root tip. Those plants also had a lower chlorophyll content in young leaves and a higher ferric-chelate reductase activity (FCR; EC 1.16.1.17) in the roots. At 9 DAT, the overall vegetative performance (plant height, fresh weight of stems and leaves) was negatively affected. At the end of the experiment (14 DAT), significant correlations were found between chlorophyll and the studied parameters. In conclusion, tomato plants experienced a cascade of responses to Fe deficiency throughout nine days: firstly, root lateralization increased; later, root swelling was observed, and a decrease in leaf chlorophyll content was registered associated with an increase in root FCR. At the end, the biomass of tomato plants decreased.

2019Journal article

Open access

Movimento e sinalização do ferro em plantas com estratégia I

Publication . Gama, Florinda Maria Martins; Correia, Maribela Pestana; Nolasco, Gustavo

A deficiência de Fe provocou decréscimos no teor de clorofila total, acréscimos na atividade da QFR, alterações morfológicas a nível radicular, diminuição de absorção e translocação de Fe nos diferentes órgãos. No morangueiro o decréscimo do Fe incidiu nas raízes, na coroa e nas flores. No Poncirus o teor de Fe diminuiu nas raízes. Como alternativa à absorção de Fe ocorreu uma acumulação dos metais Zn, Mn e Cu especialmente nas raízes e folhas novas. No morangueiro os compostos orgânicos acumularam nas folhas velhas e jovens e diminuíram nas raízes. O pulso de Fe fornecido na solução nutritiva a plantas cloróticas de morangueiro levou à recuperação da deficiência em 12 dias. A partição de Fe foi direcionada para a coroa e para as flores, associado a acumulação de ácidos sucínico e cítrico ao nível radicular e permitiu maior absorção de Fe. Foram estudadas as alterações no mecanismo de resposta em plantas com o gene FRO1 silenciado. Em plantas silenciadas a deficiência de Fe levou à redução da expressão do gene, decréscimo da atividade QFR e diminuição na síntese de clorofila. Em Nicotiana o padrão de distribuição do Fe entre folhas velhas e jovens foi alterado e não foi possível recuperar as plantas silenciadas, as plantas não conseguiram retomar o metabolismo na síntese de clorofila nem ativar a enzima QFR. Foi estudado o comportamento de porta-enxertos de Poncirus com a estratégia redutora e as adaptações fisiológica ativas quando transplantadas para solo calcário. Estas plantas apresentaram desempenho semelhante em relação às plantas que cresceram numa primeira fase sem limitação de Fe indicando que os mecanismos de adaptação e o aumento nutricional induzidos pela deficiência de Fe podem ser utilizados como uma ferramenta de defesa que contribuirá para as plantas tolerarem melhor as diferentes restrições do solo em condições de campo.

2018-07-04Doctoral thesis

Open access

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, Maribela

The 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.

2020-03Journal article

Open access