Maribela Pestana

BackgroundIron 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 µM 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 µM of Fe (as 0.5 µM would not be enough for the larger plants during phase II). Therefore, four treatments were imposed: Fe0, Fe10, VIGS‐...

Iron is an essential micronutrient for Citrus, playing an important role in photosynthesis and yield. The aim of this paper is to evaluate the tolerance to Fe deficiency of five Citrus rootstocks: sour orange (S), Carrizo citrange (C), Citrus macrophylla (M), Troyer citrange (T) and Volkamer lemon (V). Plants were grown for 5 weeks in nutrient solution that contained the following Fe concentrations (in µM): 0, 5, 10, 15 and 20. At the end of the experiment, biomass (dry weight), leaf area, total leaf chlorophyll (CHL) and the activity of root chelate activity (FCR) were registered. Additionally, the mineral composition of roots (R) and shoots (S) was evaluated. Principal Component Analysis was used to study the relationships between all parameters and, subsequently, the relations between rootstocks. In the first component, N-S, P-S, Ca-S, Cu-S, Zn-S, Mn-S and Zn-R and Mn-R concentrations were related to leaf CHL and FCR. Increases in leaf CHL, Mg-R, DW (shoots and roots) were invers...

Iron (Fe) is abundant in soils and although it is required in small amounts by plants the incidence of iron chlorosis (Fe deficiency) is very common in a number of crops and requires massive soil application of Fe-chelates to correct it. In this work, we present the most important results obtained in several experiments conducted with strawberry to study the physiological and biochemical response mechanisms to Fe deficiency, and the assessment of novel alternatives to control this nutritional disorder. In all experiments, conducted in hydroponic systems, symptoms were induced by withdrawing Fe from the solution and the results were compared to a control treatment grown with Fe. The degree of chlorosis and symptoms recovery was estimated using SPAD values. The activity of iron chelate reductase, the enzyme responsible for Fe reduction in roots, was determined in root apices by colorimetric quantification of the BPDS complex. The Fe concentration in leaves and roots was quantified by ...

Abstract The traditional agricultural production systems are evolving more toward organic, sustainable or environmental friendly systems and products; however, it is important to keep the yield and the quality of crops. The aim of this work was to evaluate the recovery of iron deficient strawberry plants by foliar spray, using a gramineous plants extract (GE). Bare-root transplants of strawberry (Fragaria × ananassa Duch. cv “Diamond”) were grown in a Hoagland’s nutrient solution with iron (Fe10) or without (Fe0). Forty-two days after Fe deprivation, plants grown without iron became chlorotic and GE was applied. Three foliar applications were done, once per week and the regreening was monitored using a SPAD apparatus. After two applications, a rapid but transient regreening was detected in young leaves. Nevertheless, biomass and root/shoot ratio of recovered plants (GE treatment) were similar to chlorotic plants (Fe0 treatment). Phosphorous, Mn and Fe contents were higher in crowns of GE plants at the end of the experiment (67 days). The concentration of organic acids and ferric chelate–reductase (FC-R) activity was also significantly higher in GE treatment. It is possible that the high chelating capacity of the extract was responsible for the Fe internal transport and use.

Water availability for irrigation of intensive crops will become a major problem in southern Iberia. One of the tools to sustain land use under water shortage is to choose crops well adapted to those environmental stress conditions featuring low water demand. The aim of this paper is to explore several relationships between climatic variables and the fruit production of carob-tree (yield) in a series of 30 consecutive years (1985–2015) referred to one single orchard. Precipitation and air temperature were the selected variables and regression models were tested. It was not possible to find any relations between yield and temperature, but precipitation during the hydrological year was inversely and significantly related to yield (Model 1- R2 = 0.18). A close analysis indicated that rainfall registered during autumn was particularly effective, since higher yields were obtained in the years with less rainfall registered in the period September + October + November (SON) (Model 2; R2 = 0.21). Although the air temperature effect was not found significant, mean values between 22.0 and 24.5 °C during SON were crucial to flowering and yield. Model 2 was validated using an independent data set considering 3 years, and the calculated yields were overestimated by 18.6% and 4.0% in two consecutive seasons. Moreover, Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios predict a precipitation decrease for SON period in the region, which may create favorable conditions for insect pollination and fruiting success. Precipitation and air temperature in a 30-year period are correlated with carob (a dry fruit) production in southern Portugal Higher precipitation during September + October + November (SON) is related to lower yield Climatic forecast using RCP scenarios indicates a decrease in precipitation during SON for the next decades which may lead to higher yield.

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 pla...

Sarcocornia fruticosa (L.) A.J. Scott is a dicotyledonous halophyte that grows in areas with an arid climate such as the marshes of southern Spain. The species has potential uses for saline agriculture and biofuel production, but the effects of salt stress on its nutrition and physiology remain unclear. Plants of S. fruticosa were grown in pots with a mixture of sphagnum peat-moss and Perlite. In order to evaluate the effects of different levels of salinity, five treatments using different NaCl concentrations (10 (control), 60, 100, 200 and 300 mM NaCl) were applied over a period of 60 days. At the end of the experiment, the dry weight, the biomass allocation and the tissue water content were measured for each salinity treatment. The net uptake of various nutrients and their translocation rates were calculated for each salt treatment. Salt loss, shedding of plant parts and succulence in shoots were evaluated together with the K+/Na+ ratio, K-Na selectivity, concentrations of osmolyt...

To 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 (FRO1) 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 μM 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 FRO1 silencing had occurred, resupply of Fe (R) was done by adding 2.5 μM 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)...

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 × ananassa Duch.) was used as model plant. Bare-root transplants of strawberry (cv.…