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- Halophyte fatty acids as biomarkers of anthropogenic-driven contamination in Mediterranean marshes: Sentinel species survey and development of an integrated biomarker response (IBR) indexPublication . Duarte, Bernardo; Carreiras, João; Pérez-Romero, Jesús Alberto; Mateos-Naranjo, Enrique; Redondo-Gómez, Susana; Matos, Ana Rita; Marques, J. C.; Caçador, IsabelEstuarine environments are extremely affected by anthropogenic-driven contamination, namely heavy metals. In the recent years, several organisms have been studied to be used as sentinel species providing a wide range of biomarkers for estuarine contamination. Only recently non-traditional biomarkers, such as fatty acids, were included in animal ecotoxicology and impact assessment studies. Nevertheless, there is a wide lack of knowledge regarding to its application in estuarine plants. Considering this the present work aimed to evaluate the application of fatty acid profiling in Mediterranean halophytic species chronically exposed to different degrees of metal contamination, while incorporating these fatty acid biomarkers into an unifying index. From the fatty acids analysis two different types of sentinel halophytes could be identified: the contamination sensitive Halimione portulacoides (sea purslane), Sarcocornia fruticosa (glasswort) and Spartina patens (saltmeadow cordgrass), and the contamination-tolerant Spartina maritima (small cordgrass). In sensitive species the most evident changes in the fatty acid profiles were the decrease in the 18:3 and the increase in the 16:0 fatty acid relative concentrations, while the inverse trend was recorded in the tolerant S. maritima under chronic contamination. Beyond the evident physiological importance, these shifts in the halophyte fatty acid profiles provide some understanding on their use as biomarkers of metal contamination. After application of an integrated biomarker response (IBR) index it was possible to conclude that in sensitive halophytes (H. portulacoides, S. fruticosa and S. patens) the samples collected from the contaminated site produce had higher IBR values than the tolerant species S. maritima being these lower values linked with an adaptation mechanism towards contamination. Furthermore, the fatty acid-based IBR index was intrinsically connected with the bioavailable metals concentrations in the rhizosediments, which make that it could be used in future impact assessment and/or ecotoxicology studies. In summary, the data showed that two of the most abundant halophytes in the Mediterranean eco-region (S. fruticose and H. portulacoides) are potential sentinel species of metal contamination, whereas its fatty acid profile is an efficient biomarker of the degree of environmental contamination.
- Investigating the physiological mechanisms underlying Salicornia ramosissima response to atmospheric CO2 enrichment under coexistence of prolonged soil flooding and saline excessPublication . Pérez-Romero, Jesús Alberto; Duarte, Bernardo; Barcia-Piedras, Jose-Maria; Matos, Ana Rita; Redondo-Gómez, Susana; Caçador, Isabel; Mateos-Naranjo, EnriqueA 45-days long climatic chamber experiment was design to evaluate the effect of 400 and 700 ppm atmospheric CO2 treatments with and without soil water logging in combination with 171 and 510 mM NaCl in the halophyte Salicornia ramosissima. In order to ascertain the possible synergetic impact of these factors associate to climatic change in this plant species physiological and growth responses. Our results indicated that elevated atmospheric CO2 concentration improved plant physiological performance under suboptimal root-flooding and saline conditions plants. Thus, this positive impact was mainly ascribed to an enhancement of energy transport efficiency, as indicated the greater PG, N and Sm values, and the maintaining of carbon assimilation capacity due to the higher net photosynthetic rate (AN) and water use efficiency (iWUE). This could contribute to reduce the risk of oxidative stress owing to the accumulation of reactive oxygen species (ROS). Moreover, plants grown at 700 ppm had a greater capacity to cope with flooding and salinity synergistic impact by a greater efficiency in the modulation in enzyme antioxidant machinery and by the accumulation of osmoprotective compounds and saturated fatty acids in its tissues. These responses indicate that atmospheric CO2 enrichment would contribute to preserve the development of Salicornia ramosissima against the ongoing process of increment of soil stressful conditions linked with climatic change.
- Disentangling the effect of atmospheric CO2 enrichment on the halophyte Salicornia ramosissima J. Woods physiological performance under optimal and suboptimal saline conditionsPublication . Pérez-Romero, Jesús Alberto; Idaszkin, Yanina Lorena; Barcia-Piedras, Jose-Maria; Duarte, Bernardo; Redondo-Gómez, Susana; Caçador, Isabel; Mateos-Naranjo, EnriqueA mesocosm experiment was designed to assess the effect of atmospheric CO2 increment on the salinity tolerance of the C3 halophyte Salicornia ramosissima. Thus, the combined effect of 400 ppm and 700 ppm CO2 at 0, 171 and 510 mM NaCl on plants growth, gas exchange, chlorophyll fluorescence parameters, pigments profiles, antioxidative enzyme activities and water relations was studied. Our results highlighted a positive effect of atmospheric CO2 increment on plant physiological performance under suboptimal salinity concentration (510 mM NaCl). Thus, we recorded higher net photosynthetic rate (AN) values under saline conditions and 700 ppm CO2, being this effect mainly mediated by a reduction of mesophyll (gm) and biochemical limitation imposed to salt excess. In addition, rising atmospheric CO2 led to a better plant water balance, linked with a reduction of stomatal conductante (gs) and an overall increment of osmotic potential (Ѱo) with NaCl concentration increment. In spite of these positive effects, there were no significant biomass variations between any treatments. Being this fact ascribed by the investment of the higher energy fixed for salinity stress defence mechanisms, which allowed plants to maintain more active the photochemical machinery even at high salinities, reducing the risk of ROS production, as indicated an improvement of the electron flux and a rise of the energy dissipation. Finally, the positive effect of the CO2 was also supported by the modulation of pigments profiles (mainly zeaxhantin and violaxhantin) concentrations and anti-oxidative stress enzymes, such as superoxide dismutase (SOD) and ascorbate peroxidase (APx).
- Atmospheric CO2 enrichment effect on the Cu-tolerance of the C4 cordgrass Spartina densifloraPublication . Pérez-Romero, Jesús Alberto; Idaszkin, Yanina Lorena; Duarte, Bernardo; Baeta, Alexandra; MARQUES, JOÃO CARLOS; Redondo-Gómez, Susana; Caçador, Isabel; Mateos-Naranjo, EnriqueA glasshouse experiment was designed to investigate the effect of the co-occurrence of 400 and 700ppm CO2 at 0, 15 and 45mM Cu on the Cu-tolerance of C4 cordgrass species Spartina densiflora, by measuring growth, gas exchange, efficiency of PSII, pigments profiles, antioxidative enzyme activities and nutritional balance. Our results revealed that the rising atmospheric CO2 mitigated growth reduction imposed by Cu in plants grown at 45mM Cu, leading to leaf Cu concentration bellow than 270mgKg-1 Cu, caused by an evident dilution effect. On the other hand, non-CO2 enrichment plants showed leaf Cu concentration values up to 737.5mgKg-1 Cu. Furthermore, improved growth was associated with higher net photosynthetic rate (AN). The beneficial effect of rising CO2 on photosynthetic apparatus seems to be associated with a reduction of stomatal limitation imposed by Cu excess, which allowed these plants to maintain greater iWUE values. Also, plants grown at 45mM Cu and 700ppm CO2, showed higher ETR values and lower energy dissipation, which could be linked with an induction of Rubisco carboxylation and supported by the recorded amelioration of N imbalance. Furthermore, higher ETR values under CO2 enrichment could lead to an additional consumption of reducing equivalents. Idea that was reflected in the lower values of ETRmax/AN ratio, malondialdehyde (MDA) and ascorbate peroxidase (APx), guaiacol peroxidase (GPx) and superoxide dismutase (SOD) activities under Cu excess, which could indicate a lower production of ROS species under elevated CO2 concentration, due to a better use of absorbed energy.