Luísa C. Carvalho
University of Lisbon
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Featured researches published by Luísa C. Carvalho.
International Journal of Plant Sciences | 2006
Luísa C. Carvalho; B. Jorge Vilela; Patrícia Vidigal; Philip M. Mullineaux; Sara Amâncio
Micropropagated grapevine (Vitis vinifera L. var. Touriga Nacional) was transferred from heterotrophic growth conditions and PPFD of 50 μmol m−2 s−1 to ex vitro under PPFD fourfold higher, which causes photooxidative stress. We have analyzed the first 7 d of growth, focusing on the protective role of the ascorbate‐glutathione cycle and relating its activity to the functioning of photosynthetic electron transport. Immediately after transfer, reversible photoinhibition was observed. Both the photochemical efficiency of PSII and PSII excitation capture efficiency were transiently affected. Concomitantly, a transient rise in H2O2 content was observed on day 1, followed by increased activity of the ascorbate‐glutathione cycle as determined by changes to ascorbate and glutathione levels and redox states, enzyme activities, and expression of associated genes. The upregulation of ascorbate peroxidase (APX1 and APX3), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GOR2) was observed from day 1, followed by catalase (CAT) on day 2. Accompanying changes to ascorbate‐glutathione cycle activity, the expression of superoxide dismutase isoforms increased. A slight H2O2 peak, not accompanied by photoinhibition, was observed on day 6. A decrease in the ascorbate and glutathione pools also pointed to the development of new leaves, with the concurring translocation of metabolites.
Plant Biology | 2016
Luísa C. Carvalho; João L. Coito; Elsa F. Gonçalves; Maria Manuela Chaves; Sara Amâncio
Worldwide, extensive agricultural losses are attributed to drought, often in combination with heat in Mediterranean climate regions, where grapevine traditionally grows. The available scenarios for climate change suggest increases in aridity in these regions. Under natural conditions plants are affected by a combination of stresses, triggering synergistic or antagonistic physiological, metabolic or transcriptomic responses unique to the combination. However the study of such stresses in a controlled environment can elucidate important mechanisms by allowing the separation of the effects of individual stresses. To gather those effects, cuttings of two grapevine varieties, Touriga Nacional (TN) and Trincadeira (TR), were grown under controlled conditions and subjected to three abiotic stresses (drought - WS, heat - HS and high light - LS) individually and in combination two-by-two (WSHS, WSLS, HSLS) or all three (WSHSLS). Photosynthesis, water status, contents of H2 O2 , abscisic acid and metabolites of the ascorbate-glutathione cycle were measured in the leaves. Common and distinct response features were identified in the different stress combinations. Photosynthesis was not hindered in TN by LS, while even individual stresses severely affect photosynthesis in TR. Abscisic acid may be implicated in grapevine osmotic responses since it is correlated with tolerance parameters, especially in combined stresses involving drought. Overall, the responses to drought-including treatments were clearly distinct to those without drought. From the specific behaviours of the varieties, it can be concluded that TN shows a higher capacity for heat dissipation and for withstanding high light intensities, indicating better adjustment to warm conditions, provided that water supply is plentiful.
Plant Cell and Environment | 2015
Luísa C. Carvalho; João L. Coito; Silvana Colaço; Maurício Sangiogo; Sara Amâncio
Heat stress is a major limiting factor of grapevine production and quality. Acclimation and recovery are essential to ensure plant survival, and the recovery mechanisms can be independent of the heat response mechanisms. An experimental set up with and without acclimation to heat followed by recovery [stepwise acclimation and recovery (SAR) and stepwise recovery (SR), respectively] was applied to two grapevine varieties, Touriga Nacional (TN), and Trincadeira (TR), with different tolerance to abiotic stress. Major differences were found between leaves of SAR and SR, especially after recovery; in SAR, almost all parameters returned to basal levels while in SR they remained altered. Acclimation led to a swifter and short-term antioxidative response, affecting the plant to a lesser extent than SR. Significant differences were found among varieties: upon stress, TN significantly increased ascorbate and glutathione reduction levels, boosting the cells redox-buffering capacity, while TR needed to synthesize both metabolites, its response being insufficient to keep the redox state at working levels. TR was affected by stress for a longer period and the up-regulation pattern of antioxidative stress genes was more obvious. In TN, heat shock proteins were significantly induced, but the canonical heat-stress gene signature was not evident probably because no shutdown of the housekeeping metabolism was needed.
Tropical Plant Biology | 2009
Carlos Aragón; Luísa C. Carvalho; Justo González; Maritza Escalona; Sara Amâncio
Previous results have shown that sugarcane plantlets micropropagated in Temporary Immersion Bioreactors (TIB) demonstrated a better morphology and physiological behaviour when compared to plantlets propagated in Gelled Medium (GM). The present work focuses on the onset of oxidative stress symptoms at transfer to ex vitro and during acclimatization. The specific ROS being produced were identified and tissue-located by infiltrating leaves with specific O2−.and H2O2 staining dyes, respectively NBT and DAB. TIB plantlets showed trichomes stained with NBT and DAB, their density decreasing with time. Stomata were coloured with NBT and DAB in GM and, at the end of acclimatization, plantlets from both systems presented the lowest level of staining of both stomata and trichomes. The response of the anti-oxidative system was also analysed through in vitro and in gel enzyme activities and transcription levels of genes for key response enzymes. At the end of the in vitro phase, GM plantlets showed higher activities of APX and MDHAR, while CAT, GR, GT and DHAR activities increased in TIB. At the end of acclimatization SOD and CAT increased mainly in TIB, while GM induced the increase of APX. The immunobloting of peroxiredoxins showed that Prxs were expressed at higher levels in TIB plantlets, some showing polymerization. The transcription of genes coding for key response enzymes was strongly up-regulated in GM plantlets. In conclusion and comparing with GM, TIB produced plantlets closer to autotrophy and with improved mobilization of the anti-oxidative response.
Journal of Integrative Plant Biology | 2015
Patrícia Vidigal; Ana Montserrat Martín-Hernández; Cèlia Guiu-Aragonés; Sara Amâncio; Luísa C. Carvalho
Peroxiredoxins (Prx) catalyse the reduction of hydrogen peroxide (H2O2) and, in association with catalases and other peroxidases, may participate in signal transduction by regulating intercellular H2O2 concentration that in turn can control gene transcription and cell signaling. Using virus-induced-gene-silencing (VIGS), 2-Cys Peroxiredoxin (2CysPrx) family and type-II Peroxiredoxin B (PrxIIB) gene were silenced in Nicotiana benthamiana, to study the impact that the loss of function of each Prx would have in the antioxidant system under control (22 °C) and severe heat stress conditions (48 °C). The results showed that both Prxs, although in different organelles, influence the regeneration of ascorbate to a significant extent, but with different purposes. 2CysPrx affects abscisic acid (ABA) biosynthesis through ascorbate, while PrxIIB does it probably through the xanthophyll cycle. Moreover, 2CysPrx is key in H2O2 scavenging and in consequence in the regulation of ABA signaling downstream of reactive oxygen species and PrxIIB provides an important assistance for H2O2 peroxisome scavenges.
Archive | 2014
Maria Manuela Abreu; Jaume Bech; Luísa C. Carvalho; Erika S. Santos
Chemical elements exist naturally in the environment with different concentrations. However, human activities can increase these concentrations, what represent a serious threat to ecosystems and to the human health. In soil, the chemical elements are distributed in different physicochemical forms; inorganic species, organic complexes, adsorbed on solid phases or as constituents of solid phases with different solubility degrees. Plants can absorb only the elements present in the so-called available fraction, which is associated to the exchange complexes and soluble fractions in the soil solution. Absorption, translocation and accumulation of the elements in the plants depend on the species and ecotype as well as on the plant organ, climatic conditions and season of the year. Usually, essential elements (macro and micro-nutrients) are absorbed and translocated to the aerial part of the plant, while toxic elements are retained in the roots, however some hazardous elements are also transported to shoots. High concentrations of toxic elements in the plants can affect their biological processes and/or trigger different physiological responses to combat the oxidative stress (e.g. antioxidative enzymes, glutathione, phytochelatins). The elements accumulated in edible organs of crops or in spontaneous plants represent the major entry point in the food chain. Even at concentrations below phytotoxic levels, hazardous elements can pose health risks for humans due to the augmentation effect along the food chain. The objective of this chapter was to elucidate/clarify the pathways of the chemical elements in the soil-plant-human system as well as the physiological mechanisms that plants develop to respond to the absorption and accumulation of hazardous chemical elements.
International Journal of Plant Sciences | 2008
Sílvia Tavares; Cátia Sousa; Luísa C. Carvalho; Sara Amâncio
A cell system of two Vitis species, Vitis vinifera cv. Touriga Nacional and Vitis rupestris, was chosen to study the response to sulfate deficiency and sulfate resupply through the analysis of sulfate influx and the expression of sulfate transporter transcripts. Cell suspensions were grown under two sulfate conditions: S sufficient (+S; 1.5 mM of MgSO4) and S deficient (−S). Both species were equally affected by the S‐deficient conditions of the medium. After 24 h in −S medium, cells of both species showed a significant increase in sulfate influx rate, which was maintained throughout the culture cycle, reaching a maximum at days 4–5 in −S conditions. The relative expression of sulfate transporters from V. vinifera and V. rupestris, VvST and VrST, analyzed by real‐time PCR, confirmed a strong derepression of the sulfate transporters in −S conditions. The enhanced influx rates and the upregulation of VvST and VrST were rapidly reversed by the addition of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape
Plant Signaling & Behavior | 2008
B. Jorge Vilela; Luísa C. Carvalho; Sara Amâncio
Physiologia Plantarum | 2018
Luísa C. Carvalho; Sara Amâncio
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Environmental Science and Pollution Research | 2018
Daniel Arenas-Lago; Erika S. Santos; Luísa C. Carvalho; Maria Manuela Abreu; M.L. Andrade