Exploring Local Maize Diversity for Increased Agricultural Sustainability: New Insights into Drought Stress Response and Recovery of Guinea-Bissau Landraces

Landraces are rightfully known as the backbone of sustainable food production, particularly in areas experiencing significant environmental constraints. However, protecting landraces from genetic erosion and valuing their potential for plant breeding and sustainable food production requires in-depth understanding of their phenotypic traits. Two Guinea-Bissau landraces (GA, GV) and two elite cultivars (P98438, P0023) were subjected to drought stress for 7 (S1) and 12 (S2) days. After this period plants were rewatered (R). The relative water content (RWC) was unchanged in S1 and decreased in S2 in all genotypes. Chlorophyll a fluorescence parameters changed moderately in S1 and remarkably in S2, including on GA and GV plants, where a decrease of Fv/Fm and PI, and an increase in absorbed, trapped, and dissipated energy per reaction center, was found. P0023 plants showed the most contrasting behavior to Guinea-Bissau genotypes, presenting an increase in Fv/Fm and PI values and a decrease in the specific energy fluxes per reaction center (RC), whereas P9838 presented an intermediate behavior. Drought (S1 and S2) decreased the amount of chlorophyll (Chl.) and carotenoids in GA and GV plants. On the contrary, in the P0023, the only pigment to decrease with stress was Chl. b. Fatty acid (FA) analyses allowed for the identification of C16:0, C18:2, and C18:3 in larger amounts, and C14:0, C16:1t, C18:0, and C18:1 acids in lower abundance. Drought stress decreased C18:3, the double bond index, and the total FA (except for P0023 and GV in S2) and increased C14:0 and C16:0 acids. The expression of phospholipase D (PLD) was higher at S2. After recovery, PLD expression presented a notorious decrease on the Guinea-Bissau landraces. P0023 showed the smallest alterations after recovery, while Guinea’s plants suffered more radical alterations leading to the conclusion that Guinea’s landraces were more drought-sensitive and that their recovery rate was impaired.info:eu-repo/semantics/publishedVersio

Effects of Glyphosate-Based Herbicide on Primary Production and Physiological Fitness of the Macroalgae Ulva lactuca

The use of glyphosate-based herbicides (GBHs) worldwide has increased exponentially over the last two decades increasing the environmental risk to marine and coastal habitats. The present study investigated the effects of GBHs at environmentally relevant concentrations (0, 10, 50, 100, 250, and 500 g L1) on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems and energy balance) of Ulva lactuca, a cosmopolitan marine macroalgae species. Although GBHs cause deleterious effects such as the inhibition of photosynthetic activity, particularly at 250 g L1, due to the impairment of the electron transport in the chloroplasts, these changes are almost completely reverted at the highest concentration (500 g L1). This could be related to the induction of tolerance mechanisms at a certain threshold or tipping point. While no changes occurred in the energy balance, an increase in the pigment antheraxanthin is observed jointly with an increase in ascorbate peroxidase activity. These mechanisms might have contributed to protecting thylakoids against excess radiation and the increase in reactive oxygen species, associated with stress conditions, as no increase in lipid peroxidation products was observed. Furthermore, changes in the fatty acids profile, usually attributed to the induction of plant stress response mechanisms, demonstrated the high resilience of this macroalgae. Notably, the application of bio-optical tools in ecotoxicology, such as pulse amplitude modulated (PAM) fluorometry and laser-induced fluorescence (LIF), allowed separation of the control samples and those treated by GBHs in different concentrations with a high degree of accuracy, with PAM more accurate in identifying the different treatmentsinfo:eu-repo/semantics/publishedVersio

DESESTRUTURAÇÃO DE ECONOMIAS HETEROGÊNEAS : ensaio de uma análise para a região do Cerrado Piauiense

O recente processo de ocupação e de uso das terras do cerrado piauiense experimentou transformações que culminaram na apropriação privada de terras, para atender a um padrão de reprodução do capital, negando a heterogeneidade socioeconômica dos nativos da região. Diante do exposto, o principal intuito deste ensaio é, a partir diálogo com a discussão teórica dos comuns, desenvolvida em Dardot e Laval (2017) com a heterogeneidade econômica de Thompson (1998) e Polanyi (2000; 2012), construir elementos de análise que concorram para uma melhor apreensão do impacto da desestruturação econômica em curso na região deste estudo. Como resultado, se evidencia uma metamorfose na ocupação e uso dos solos, a desestruturação da heterogeneidade produtiva, a transição do trabalhador camponês para o assalariado rural, assim como a homogeneização da base monetária local

LipidTOX: A fatty acid-based index efficient for ecotoxicological studies with marine model diatoms exposed to legacy and emerging contaminants

Contaminants, when present above certain thresholds, can induce physiological constraints to organisms, namely diatoms, a model group representative of marine phytoplankton, triggering feedback mechanisms, such as changes in cell’s fatty acid profiles, that can be used as biomarkers towards xenobiotic exposure. Having this in mind and considering the ecological relevance of diatom fatty acid profiles as well as their recognized potential as biomarkers of contaminant exposure, the present work aims to develop and test the accuracy of an integrative multi-biomarker response index based on the fatty acid profiles of marine diatoms (using Phaeodactylum tricornutum as model diatom) exposed to several emerging contaminants. In terms of the impacts at the individual fatty acid level, it was possible to observe changes transversal to different contaminants, such as the reduction of C14:0 and C16:0 fatty acids, with increasing xenobiotic concentration, as observed, for example, under propranolol and fluoxetine exposure. Enhancement of C16:2n-7 and C16:3n-4 concentrations as well as complete disruption of the basal fatty acid profile was observed in diatoms exposed to copper nanoparticles. These individual diverse and intrinsically connected alterations in fatty acid concentrations depended on the type and dose of the xenobiotic applied, highlighting the need to address these profiles as a whole. The evaluation of the diatom cells’ fatty acids using a multivariate approach revealed a high degree of sensitivity of these biochemical traits to disclose the type of xenobiotic applied to the diatoms, as well as the exogenous concentration used. These biochemical profiles were later incorporated into a unifying numerical index (LipidTOX) using an integrated biomarker response approach. The LipidTOX index showed strong correlations with both the exogenous xenobiotic concentration applied as well as with the growth features assessed for the exposed cultures, revealing a very high efficiency in translating growth impairments imposed by each of the xenobiotics tested at the different test concentrations. The LipidTOX index proved to be an efficient tool for ecotoxicological assays with marine model diatoms and evidenced a high degree of reliability for classifying the exposure of the cells to emerging contaminants. The results and benefits of the LipidTOX index application can be easily communicated to non-expert audiences such as stakeholders, policymakers and environmental managers so that this approach can be used in future toxicological evaluations of the impacts of classical and emerging xenobiotics in marine primary producers.info:eu-repo/semantics/publishedVersio

LipidTOX: a fatty acid-based index efficient for ecotoxicological studies with marine model diatoms exposed to legacy and emerging contaminants

Contaminants, when present above certain thresholds, can induce physiological constraints to organisms, namely diatoms, a model group representative of marine phytoplankton, triggering feedback mechanisms, such as changes in cell’s fatty acid profiles, that can be used as biomarkers towards xenobiotic exposure. Having this in mind and considering the ecological relevance of diatom fatty acid profiles as well as their recognized potential as biomarkers of contaminant exposure, the present work aims to develop and test the accuracy of an integrative multi-biomarker response index based on the fatty acid profiles of marine diatoms (using Phaeodactylum tricornutum as model diatom) exposed to several emerging contaminants. In terms of the impacts at the individual fatty acid level, it was possible to observe changes transversal to different contaminants, such as the reduction of C14:0 and C16:0 fatty acids, with increasing xenobiotic concentration, as observed, for example, under propranolol and fluoxetine exposure. Enhancement of C16:2n-7 and C16:3n-4 concentrations as well as complete disruption of the basal fatty acid profile was observed in diatoms exposed to copper nanoparticles. These individual diverse and intrinsically connected alterations in fatty acid concentrations depended on the type and dose of the xenobiotic applied, highlighting the need to address these profiles as a whole. The evaluation of the diatom cells’ fatty acids using a multivariate approach revealed a high degree of sensitivity of these biochemical traits to disclose the type of xenobiotic applied to the diatoms, as well as the exogenous concentration used. These biochemical profiles were later incorporated into a unifying numerical index (LipidTOX) using an integrated biomarker response approach. The LipidTOX index showed strong correlations with both the exogenous xenobiotic concentration applied as well as with the growth features assessed for the exposed cultures, revealing a very high efficiency in translating growth impairments imposed by each of the xenobiotics tested at the different test concentrations. The LipidTOX index proved to be an efficient tool for ecotoxicological assays with marine model diatoms and evidenced a high degree of reliability for classifying the exposure of the cells to emerging contaminants. The results and benefits of the LipidTOX index application can be easily communicated to non-expert audiences such as stakeholders, policymakers and environmental managers so that this approach can be used in future toxicological evaluations of the impacts of classical and emerging xenobiotics in marine primary producers.info:eu-repo/semantics/publishedVersio

Ecotoxicological Effects of the Anionic Surfactant Sodium Dodecyl Sulfate (SDS) in Two Marine Primary Producers: Phaeodactylum tricornutum and Ulva lactuca

Sodium Dodecyl Sulfate (SDS) is an anionic surfactant, extensively used in detergents, household and personal care products, as well as in industrial processes. The present study aimed to disclose the potential toxicological effects of SDS exposure under environmentally relevant concentrations (0, 0.1, 1, 3, and 10 mg L−1 ) on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems, and energy balance) of two marine autotrophs: the diatom Phaeodactylum tricornutum and the macroalgae Ulva lactuca. A growth rate (GR) reduction in P. tricornutum was observed with a classic dose-response effect towards the highest applied concentration, while a GR increase occurred in U. lactuca. Regarding photochemistry, the decrease in the fluorescence of the OJIP curves and laser-induced fluorescence allowed a better separation between SDS treatments in U. lactuca compared with P. tricornutum. Although all pigments significantly decreased in U. lactuca at the highest concentrations (except for antheraxanthin), no significant variations occurred in P. tricornutum. On the other hand, changes in fatty acid content were observed in P. tricornutum but not in U. lactuca. In terms of classical biomarker assessment, a dose-effect relationship of individual biomarkers versus SDS dose applied; U. lactuca displayed a higher number of biomarker candidates, including those in distinct metabolic pathways, increasing its usefulness for ecotoxicological applications. By evaluating the potential application of optical and biochemical traits, it was evident that the fatty acid profiles of the different exposure groups are excellent candidates in P. tricornutum, concomitant with the characteristics of this anionic surfactant. On the other hand, the results presented by laser-induced fluorescence and some parameters of PAM fluorometry in U. lactuca may be an advantage in the field, offering non-invasive, fast, easy-to-use, high-throughput screening techniques as excellent tools for ecotoxicology assessment.info:eu-repo/semantics/publishedVersio

Ecoengineering Solutions for the Impairment of Spreading and Growth of Invasive Spartina patens in Mediterranean Salt Marshes

The invasion of natural communities by non-indigenous species represents one of the most serious threats to biodiversity. Understanding the ecophysiology of invasive species can provide insights into potential physiological handicaps relative to native species. By doing so, we can leverage the development of ecoengineering solutions for the removal of non-indigenous species, preferably using non-chemical methods. Spartina patens is a known invasive species of cordgrass aggressively proliferating in Mediterranean salt marshes, producing impenetrable monospecific stands. As its occurrence is delimited by the upper high tide water level, we hypothesized that S. patens is intolerant to waterlogging. Therefore, we developed a field experiment where strands of S. patens were kept waterlogged over the entire tidal cycle for 30 days. At the end of the experimental period, plants in the trial plots exhibited severe stress symptoms at different physiological levels compared with control plots (no intervention). At the photobiological level, intervened plants exhibited lower efficiency in producing chemical energy from light, whilst at the biochemical level waterlogging impaired the antioxidant system and increased lipid peroxidation products. Furthermore, the application of chlorophyll a pulse amplitude modulated (PAM) fluorometry, a non-invasive technique, allowed us to evaluate the effectiveness of the implemented measures, being the tool that provided the best separation between the control and intervened population. Considering the physiological traits observed here, ecoengineering solutions based on increased waterlogging of S. patens stands, can be a low-cost and efficient measure to reduce the spreading and growth of this invasive species in the Mediterranean and other salt marshes worldwide with little disturbance.info:eu-repo/semantics/publishedVersio

Glyphosate-Based Herbicide Toxicophenomics in Marine Diatoms: Impacts on Primary Production and Physiological Fitness

Glyphosate is the main active component of the commercial formulation Roundup®, the most widely used chemical herbicide worldwide. However, its potential high toxicity to the environment and throughout trophic webs has come under increasing scrutiny. The present study aims to investigate the application of bio-optical techniques and their correlation to physiological and biochemical processes, including primary productivity, oxidative stress, energy balance, and alterations in pigment and lipid composition in Phaeodactylum tricornutum, a representative species of marine diatoms, using the case study of its response to the herbicide glyphosate-based Roundup® formulation, at environmentally relevant concentrations. Cultures were exposed to the herbicide formulation representing effective glyphosate concentrations of 0, 10, 50, 100, 250, and 500 μg L−1. Results showed that high concentrations decreased cell density; furthermore, the inhibition of photosynthetic activity was not only caused by the impairment of electron transport in the thylakoids, but also by a decrease of antioxidant capacity and increased lipid peroxidation. Nevertheless, concentrations of one of the plastidial marker fatty acids had a positive correlation with the highest concentration as well as an increase in total protein. Cell energy allocation also increased with concentration, relative to control and the lowest concentration, although culture growth was inhibited. Pigment composition and fatty acid profiles proved to be efficient biomarkers for the highest glyphosate-based herbicide concentrations, while bio-optical data separated controls from intermediate concentrations and high concentrations.info:eu-repo/semantics/publishedVersio

Effect Biomarkers of the Widespread Antimicrobial Triclosan in a Marine Model Diatom

The present-day COVID-19 pandemic has led to the increasing daily use of antimicrobials worldwide. Triclosan is a manmade disinfectant chemical used in several consumer healthcare products, and thus frequently detected in surface waters. In the present work, we aimed to evaluate the effect of triclosan on diatom cell photophysiology, fatty acid profiles, and oxidative stress biomarkers, using the diatom Phaeodactylum tricornutum as a model organism. Several photochemical effects were observed, such as the lower ability of the photosystems to efficiently trap light energy. A severe depletion of fucoxanthin under triclosan application was also evident, pointing to potential use of carotenoid as reactive oxygen species scavengers. It was also observed an evident favouring of the peroxidase activity to detriment of the SOD activity, indicating that superoxide anion is not efficiently metabolized. High triclosan exposure induced high cellular energy allocation, directly linked with an increase in the energy assigned to vital functions, enabling cells to maintain the growth rates upon triclosan exposure. Oxidative stress traits were found to be the most efficient biomarkers as promising tools for triclosan ecotoxicological assessments. Overall, the increasing use of triclosan will lead to significant effects on the diatom photochemical and oxidative stress levels, compromising key roles of diatoms in the marine system.info:eu-repo/semantics/publishedVersio

Effects of Glyphosate-Based Herbicide on Primary Production and Physiological Fitness of the Macroalgae Ulva lactuca

The use of glyphosate-based herbicides (GBHs) worldwide has increased exponentially over the last two decades increasing the environmental risk to marine and coastal habitats. The present study investigated the effects of GBHs at environmentally relevant concentrations (0, 10, 50, 100, 250, and 500 µg·L −1 ) on the physiology and biochemistry (photosynthesis, pigment, and lipid composition, antioxidative systems and energy balance) of Ulva lactuca, a cosmopolitan marine macroalgae species. Although GBHs cause deleterious effects such as the inhibition of photosynthetic activity, particularly at 250 µg·L −1 , due to the impairment of the electron transport in the chloroplasts, these changes are almost completely reverted at the highest concentration (500 µg·L −1 ). This could be related to the induction of tolerance mechanisms at a certain threshold or tipping point. While no changes occurred in the energy balance, an increase in the pigment antheraxanthin is observed jointly with an increase in ascorbate peroxidase activity. These mechanisms might have contributed to protecting thylakoids against excess radiation and the increase in reactive oxygen species, associated with stress conditions, as no increase in lipid peroxidation products was observed. Furthermore, changes in the fatty acids profile, usually attributed to the induction of plant stress response mechanisms, demonstrated the high resilience of this macroalgae. Notably, the application of bio-optical tools in ecotoxicology, such as pulse amplitude modulated (PAM) fluorometry and laser-induced fluorescence (LIF), allowed separation of the control samples and those treated by GBHs in different concentrations with a high degree of accuracy, with PAM more accurate in identifying the different treatments.info:eu-repo/semantics/publishedVersio