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Previous studies on RNase R have highlighted significant effects of this ribonuclease in several processes of Streptococcus pneumoniae biology. In this work we show that elimination of RNase R results in overexpression of most of genes encoding the components of type II fatty acid biosynthesis (FASII) cluster. We demonstrate that RNase R is implicated in the turnover of most of transcripts from this pathway, affecting the outcome of the whole FASII cluster, and ultimately leading to changes in the membrane fatty acid composition. Our results show that the membrane of the deleted strain contains higher proportion of unsaturated and long-chained fatty acids than the membrane of the wild type strain. These alterations render the RNase R mutant more prone to membrane lipid peroxidation and are likely the reason for the increased sensitivity of this strain to detergent lysis and to the action of the bacteriocin nisin. Reprogramming of membrane fluidity is an adaptative cell response crucial for bacterial survival in constantly changing environmental conditions. The data presented here is suggestive of a role for RNase R in the composition of S. pneumoniae membrane, with strong impact on pneumococci adaptation to different stress situations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The apoplast is the plant compartment present between the plasma membrane and the cuticle, comprised of the cell wall and the extracellular spaces where the "secretomes" are released and where the apoplastic fluid circulates. Within the many functions attributed to this compartment, its role in plant-pathogen interactions is irrefutable. It is the major point where plant and pathogen secretomes come in contact and several plant and pathogenic secreted proteins and small molecules present in this compartment are already cataloged in the literature. In plant-pathogen interactions, fatty acids and lipid molecules were shown to play a crucial role in the activation of plant immunity; however, the lipid composition of the apoplast is still a black box. Most of the studies performed to understand apoplast dynamics have used proteomic-based techniques; however, knowledge about apoplastic proteins involved in lipid metabolism and transport is still severely limited. In grapevine, only three studies have been published so far focusing on the characterization of this compartment and only one of them deals with grapevine-pathogen interaction. Here we refer to our recently established method for grapevine leaves' apoplastic fluid isolation and describe a direct methylation protocol for the analysis of apoplastic fluid fatty acids. We also point out a novel intracellular marker that may be used to assess apoplastic fluid purity., (© 2023. His Majesty the King in Right of Canada, as represented by the Minister of Agriculture and Agri-Food.)

Under certain abiotic conditions (elevated irradiance, temperature and sediment salinity) observed mostly during the Mediterranean summer, the halophyte Sarcocornia fruticosa suffers a metabolic shift evidenced by a red coloration, evidencing the presence of two physiotypes (green and red). Previous works indicated that this metabolic shift has severe implications in the primary photochemistry of this species, impairing the light and carbon harvesting. Under stress plants have lower light use efficiencies and are more prone to photoinhibition, and thus this metabolic shift is essential for this species to deal with the high light intensities characteristic from this time of the year. Nevertheless, the fatty acid and lipid remodelling in green and red S. fruticosa physiotypes was not previously evaluated nor its relations with this metabolic shift. The evaluation of the lipid landscape suggests several lipid and fatty acid remodelling when comparing both red and green physiotype, as strategies to overcome stress. The galactolipids of the red physiotype suffer several changes aiming to keep chloroplast membrane structural and functional stability during water stress and can also be related to an improvement of the plants response to osmotic stress. At the phospholipid level, a readjustment of its fatty acid profiles was also observable. This remodelling allows the plants to adjust membrane fluidity the imposed osmotic stress, being this action transversal to choroplastidial, extraplastidial, and involves the action of the different phospholipids. Additionally, neutral lipids (NLs) also appear to play a role in osmotic stress adaptation, with an increase content in C18 fatty acids in the red physiotype. The resulting lipid landscape in both physiotypes presents very specific signatures that can be used as biomarkers to track this kind of metabolic shifts, in future studies with similar species., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Pharmaceutical residues impose a new and emerging threat to the marine environment and its biota. In most countries, ecotoxicity tests are not required for all pharmaceutical residues classes and, even when mandatory, these tests are not performed using marine primary producers such as diatoms. These microalgae are among the most abundant class of primary producers in the marine realm and key players in the marine trophic web. Blood-lipid-lowering agents such as bezafibrate and its derivatives are among the most prescribed drugs and most frequently found human pharmaceuticals in aquatic environments. The present study aims to investigate the bezafibrate ecotoxicity and its effects on primary productivity and lipid metabolism, at environmentally relevant concentrations, using the model diatom Phaeodactylum tricornutum. Under controlled conditions, diatom cultures were exposed to bezafibrate at 0, 3, 6, 30 and 60 μg L -1 , representing concentrations that can be found in the vicinity of discharges of wastewater treatment plants. High bezafibrate concentrations increased cell density and are suggested to promote a shift from autotrophic to mixotrophic metabolism, with diatoms using light energy generated redox potential to breakdown bezafibrate as carbon source. This was supported by an evident increase in cell density coupled with an impairment of the thylakoid electron transport and consequent photosynthetic activity reduction. In agreement, the concentrations of plastidial marker fatty acids showed negative correlations and Canonical Analysis of Principal coordinates of the relative abundances of fatty acid and photochemical data allowed the separation of controls and cells exposed to bezafibrate with high classification efficiency, namely for photochemical traits, suggesting their validity as suitable biomarkers of bezafibrate exposure. Further evaluations of the occurrence of a metabolic shift in diatoms due to exposure to bezafibrate is paramount, as ultimately it may reduce O 2 generation and CO 2 fixation in aquatic ecosystems with ensuing consequences for neighboring heterotrophic organisms., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Several large-scale metabolic profiling studies have been directed to prospect crops with a major focus on yield-related traits and, ultimately, with the definition of specific markers for plant selection in breeding programs. However, some of these technologies are expensive, time-consuming and not easily feasible for a quick approach. Fatty acid profiling was described as reliable biomarkers and as a chemotaxonomic tool allowing to study not only the diversity in germplasm collections but also to discriminate their geographic origin. We have used fatty acids profiling for a preliminary assessment of Lablab purpureus (L.) Sweet (hyacinth bean) diversity and landraces discrimination. Hyacinth bean displays an enormous variability of agro-morphological traits, probably linked to the multi-purpose uses in different regions, i.e. as pulse, or as food with nutraceutical potential (Africa and Asia), forage (Africa and Australia) and ornamental (Europe and USA). Only two forage cultivars are widely marketed, cv. Rongai and cv. Highworth, with several landraces remaining to be addressed in terms of diversity. We show that fatty acids profiling was able to distinguish landraces, which display shared fatty acids with cultivars from the center of hyacinth bean diversity origin (East Africa). We propose that fatty acid profiling is a tool that may be used not only for nutritional value assessment but also as a chemodiversity tool in crop research., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Spartina patens is a highly dispersed halophytic grass invader in Mediterranean marshes. It is also characterized by having a high degree of resistance to salinity, one of the main drivers of plant zonation in salt marshes. Nevertheless, the physiological basis behind the extreme resistance of S. patens requires more detailed studies. In the present work, we aimed to study how membrane fatty acid remodeling could contribute to the resistance of this plant to salt. Spartina patens individuals exposed to increasing levels of salinity and its leaf fatty acid profile under lipid peroxidation products evaluated under all tested concentrations. A significant increase in the relative amounts of the saturated fatty acids (SFA) was observed, namely palmitic acid (C16:0), essential for PS II functioning, and stearic (C18:0) acid. The chloroplastidial trans-hexadecenoic acid (C16:1t) as well as the polyunsaturated linoleic (C18:2) and linolenic (C18:3) acids showed significant decreases in all the salt treatments. These changes led to a reduction in the double bond index in salt-treated plants which reflects reduction of the fluidity of the chloroplast membranes, which could contribute to maintain the membrane impermeable to the toxic exogenous Na. Despite the decrease observed in the total fatty acid contents in plants exposed to high salt concentrations the amounts of lipid peroxidation products decreased highlighting the resistance of this species towards toxic exogenous salt concentrations. Membrane fatty acid remodeling could represent an efficient mechanism to maintain the photosynthetic machinery of S. patens highly efficient under salt stress., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

In this work, we studied the combined effect of increased temperature and atmospheric CO2, salt and drought stress, and inoculation with plant-growth-promoting rhizobacteria (PGPR) on the growth and some nutritional parameters of the edible halophyte Salicornia ramosissima. We found that the increase in temperature and atmospheric CO2, combined with salt and drought stresses, led to important changes in S. ramosissima fatty acids (FA), phenols, and oxalate contents, which are compounds of great importance for human health. Our results suggest that the S. ramosissima lipid profile will change in a future climate change scenario, and that levels of oxalate and phenolic compounds may change in response to salt and drought stress. The effect of inoculation with PGPR depended on the strains used. Some strains induced the accumulation of phenols in S. ramosissima leaves at higher temperature and CO2 while not altering FA profile but also led to an accumulation of oxalate under salt stress. In a climate change scenario, a combination of stressors (temperature, salinity, drought) and environmental conditions (atmospheric CO2, PGPR) will lead to important changes in the nutritional profiles of edible plants. These results may open new perspectives for the nutritional and economical valorization of S. ramosissima. [ABSTRACT FROM AUTHOR]

Vitis vinifera L. is highly susceptible to the biotrophic pathogen Plasmopara viticola. To control the downy mildew disease, several phytochemicals are applied every season. Recent European Union requirements to reduce the use of chemicals in viticulture have made it crucial to use alternative and more sustainable approaches to control this disease. Our previous studies pinpoint the role of fatty acids and lipid signalling in the establishment of an incompatible interaction between grapevine and P. viticola. To further understand the mechanisms behind lipid involvement in an effective defence response we have analysed the expression of several genes related to lipid metabolism in three grapevine genotypes: Chardonnay (susceptible); Regent (tolerant), harbouring an Rpv3-1 resistance loci; and Sauvignac (resistant) that harbours a pyramid of Rpv12 and Rpv3-1 resistance loci. A highly aggressive P. viticola isolate was used (NW-10/16). Moreover, we have characterised the grapevine phospholipases C and D gene families and monitored fatty acid modulation during infection. Our results indicate that both susceptible and resistant grapevine hosts did not present wide fatty acid or gene expression modulation. The modulation of genes associated with lipid signalling and fatty acids seems to be specific to Regent, which raises the hypothesis of being specifically linked to the Rpv3 loci. In Sauvignac, the Rpv12 may be dominant concerning the defence response, and, thus, this genotype may present the activation of other pathways rather than lipid signalling. [ABSTRACT FROM AUTHOR]

The widespread use of pesticides in agriculture remains a matter of major concern, prompting a critical need for alternative and sustainable practices. To address this, the use of lipid-derived molecules as elicitors to induce defence responses in grapevine plants was accessed. A Plasmopara viticola fatty acid (FA), eicosapentaenoic acid (EPA) naturally present in oomycetes, but absent in plants, was applied by foliar spraying to the leaves of the susceptible grapevine cultivar (Vitis vinifera cv. Trincadeira), while a host lipid derived phytohormone, jasmonic acid (JA) was used as a molecule known to trigger host defence. Their potential as defence triggers was assessed by analysing the expression of a set of genes related to grapevine defence and evaluating the FA modulation upon elicitation. JA prompted grapevine immunity, altering lipid metabolism and up-regulating the expression of several defence genes. EPA also induced a myriad of responses to the levels typically observed in tolerant plants. Its application activated the transcription of defence gene's regulators, pathogen-related genes and genes involved in phytoalexins biosynthesis. Moreover, EPA application resulted in the alteration of the leaf FA profile, likely by impacting biosynthetic, unsaturation and turnover processes. Although both molecules were able to trigger grapevine defence mechanisms, EPA induced a more robust and prolonged response. This finding establishes EPA as a promising elicitor for an effectively managing grapevine downy mildew diseases. • Lipid-derived molecules offer a sustainable solution for managing grapevine diseases. • Jasmonic acid, a plant phytohormone, enhances grapevine immunity by modulating lipid metabolism and activating defence genes. • EPA, an oomycete-derived FA, induces defence mechanisms in a susceptible grapevine cultivar, resembling responses presented in tolerant grapevines. • Eicosapentaenoic acid elicits the up-regulation of defence genes, lipid signalling, and secondary metabolism. • The application of eicosapentaenoic acid elicits a stronger and longer-lasting response compared with jasmonic acid. [ABSTRACT FROM AUTHOR]

Simple Summary: Expected climate change scenarios will have inevitable and important impacts on key foundation marine species such as seagrasses. This study was aimed to understand how the dwarf eelgrass Zostera noltii leaf lipid landscapes are altered under predicted ocean warming (+4 °C) and acidification (ΔpH 0.4) conditions. A severe reduction in the leaf total fatty acid (FA) content was observed in seagrasses individually exposed to hypercapnic or warming conditions, and this depletion was ameliorated under combined exposure to ocean warming and acidification conditions. The tested treatments also impacted the FA composition of all lipid classes, with warming exposure leading to decreases in polyunsaturated fatty acids (PUFAs). Galactolipid remodeling seems to have key roles in the physiological changes observed in seagrasses under these tested conditions, highlighting the higher impact of warming and that the proposed stress alleviation effect induced by increased water-dissolved CO2 availability. Neutral lipids were substantially increased under warming conditions, mainly with increases in C18 FA, impairing their use as substrates to maintain the osmotic balance of the cells. Nonetheless, the pace at which ocean warming is occurring can overcome the ameliorative capacity induced by higher CO2 availability, leaving seagrasses under severe heat stress beyond their lipid-remodeling capacity. Coastal seagrass meadows provide a variety of essential ecological and economic services, including nursery grounds, sediment stabilization, nutrient cycling, coastal protection, and blue carbon sequestration. However, these ecosystems are highly threatened by ongoing climatic change. This study was aimed to understand how the dwarf eelgrass Zostera noltii leaf lipid landscapes are altered under predicted ocean warming (+4 °C) and hypercapnic (ΔpH 0.4) conditions. Warming and hypercapnic conditions were found to induce a severe reduction in the leaf total fatty acid, though the combined treatment substantially alleviated this depletion. The lipid discrimination revealed a significant increase in the relative monogalactosyldiacylglycerol (MGDG) content in both hypercapnic and warming conditions, allied to plastidial membrane stabilization mechanisms. Hypercapnia also promoted enhanced phosphatidylglycerol (PG) leaf contents, a mechanism often associated with thylakoid reinvigoration. In addition to changing the proportion of storage, galacto- and phospholipids, the tested treatments also impacted the FA composition of all lipid classes, with warming exposure leading to decreases in polyunsaturated fatty acids (PUFAs); however, the combination of both stress conditions alleviated this effect. The observed galactolipid and phospholipid PUFA decreases are compatible with a homeoviscous adaptation, allowing for the maintenance of membrane stability by counteracting excessive membrane fluidity. Neutral lipid contents were substantially increased under warming conditions, especially in C18 fatty acids (C18), impairing their use as substrates for fatty acylated derivatives essential for maintaining the osmotic balance of cells. An analysis of the phospholipid and galactolipid fatty acid profiles as a whole revealed a higher degree of discrimination, highlighting the higher impact of warming and the proposed stress alleviation effect induced by increased water-dissolved CO2 availability. Still, it is essential to remember that the pace at which the ocean is warming can overcome the ameliorative capacity induced by higher CO2 availability, leaving seagrasses under severe heat stress beyond their lipid remodeling capacity. [ABSTRACT FROM AUTHOR]

Featured Application: light emitting diodes (LED) illumination with different wavelengths can modulate diatom ca-rotenoid and fatty acid production. Diatoms are microscopic biorefineries producing value-added molecules, including unique pigments, triglycerides (TAGs) and long-chain polyunsaturated fatty acids (LC-PUFAs), with potential implications in aquaculture feeding and the food or biofuel industries. These molecules are utilized in vivo for energy harvesting from sunlight to drive photosynthesis and as photosynthetic storage products, respectively. In the present paper, we evaluate the effect of narrow-band spectral illumination on carotenoid, LC-PUFAs and TAG contents in the model diatom Phaeodactylum tricornutum. Shorter wavelengths in the blue spectral range resulted in higher production of total fatty acids, namely saturated TAGs. Longer wavelengths in the red spectral range increased the cell's content in Hexadecatrienoic acid (HTA) and Eicosapentaenoic acid (EPA). Red wavelengths induced higher production of photoprotective carotenoids, namely fucoxanthin. In combination, the results demonstrate how diatom value-added molecule production can be modulated by spectral light control during the growth. How diatoms could use such mechanisms to regulate efficient light absorption and cell buoyancy in the open ocean is discussed. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

• During seagrass maturation leaves undergo a fatty acid remodeling. • There is an increase in C16:1t, associated to an increase in the chloroplast membrane fluidity. • In more mature plants there is a high leaf concentration of C18:3, a direct ROS scavenger. • Long-chain polyunsaturated fatty acids content shows an increase with the biomass development. • Seagrasses are crucial essential fatty acids providers to the estuarine heterotrophic life. Seagrass beds are among the most relevant ecosystem engineers, providing essential ecosystem services for the surrounding coastal communities. Alongside, these ecosystems are among the most threaten in the world, and thus several restoration projects have been developed in the past years. Seagrasses are important sources of essential fatty acids (FA) for animals, which are unable to synthetize them. During the seagrass growth and photochemical maturation, there is a membrane remodelling, where some fatty acids are synthetized. When analysing the FA changes at different development stages, one of the first noticeable changes is the increase in C16:1t (trans-hexadecenoic acid), associated to an increase in the chloroplast membrane fluidity, essential for the efficient energy transduction processes to occur in the thylakoids. Also, interesting to observe are the high levels of omega-3 and -6 (30–43% and 18–31% of total fatty acid content, respectively) present in this seagrass, reinforcing the nutritional value of this species as source of essential fatty acids for the primary consumers. Additionally, it is possible to observe that in the more mature plants there is a high leaf concentration of C18:3. Recent reports suggest that C18:3 can act as a direct scavenger of reactive oxygen species (ROS), indicating a lower stress level, as suggested by the higher photochemical efficiency previously observed. Moreover, it is also interesting to observe that total long-chain polyunsaturated fatty acids (LC-PUFAs) content show a significant increase with the biomass development. These LC-PUFAs are not produced by higher plants and their production in animals occurs at low rates, suggesting they may have as origin the microalgae in the grass surface, adding another important ecosystem service to these prairies, as support for microalgae development and carriers of LC-PUFAs into the food web. This membrane remodelling appears to be on the basis of the photochemical maturation of these seagrasses observed in previous studies and can be used as potential and efficient tool to monitor the development stage of the prairies and its physiological status in future restoration processes. Moreover, it becomes evident that highly developed seagrass beds are crucial food source providers in terms of essential fatty acids to the estuarine heterotrophic life. [ABSTRACT FROM AUTHOR]

Determining where harvested or produced seafood comes from is a pressing issue worldwide, with growing consumers' demand for traceable and sustainable seafood products. Identifying fine-scale traceability markers is particularly important in the context of small-scale fisheries, which are prone to illegal harvesting and mislabelling and associated food safety risks. Here we explored the power of fatty acid profiling as a fine-scale tracer of the geographical origin (<30 km apart) of the Peppery furrow shell bivalve (Scrobicularia plana) and the European seabass (Dicentrarchus labrax) collected in three locations within a large, urbanized estuary. Fatty acid profiling provided a high classification accuracy of both species to their collection sites (80%–100% for the seabass and the bivalve respectively). Fatty acid profiling also allowed the determination of food lipid quality indices. The EPA + DHA values and the atherogenic (Ai), thrombogenic (Ti) and the hypocholesterolemic/hypercholesterolemic (h/H) indexes were all within ranges of high lipid-quality seafood, albeit they varied significantly among collection sites (except h/H). Overall, results highlight the strength of fatty acid profiling as a natural marker to trace the geographic origin of small-scale fisheries products, which may be integrated into a broader regulatory monitoring framework. • Small-scale fisheries are vital in many coastal areas, yet highly prone to food fraud. • Fatty acid analyses of a bivalve and seabass with >80% site classification accuracy. • Lipid quality indexes varied in bivalves and fish collected in closely related areas. • Fatty acid profiling was a useful tracer of provenance small-scale fisheries products. [ABSTRACT FROM AUTHOR]

Agriculture is facing major constraints with the increase of global warming, being drought a major factor affecting productivity. Soybean (Glycine max) is among the most important food crops due to the high protein and lipid content of its seeds despite being considerably sensitive to drought. Previous knowledge has shown that drought induces a severe modulation in lipid and fatty acid content of leaves, related to alteration of membrane structure by lipolytic enzymes and activation of signalling pathways. In that sense, little is known on lipid modulation and lipolytic enzymes' role in soybean drought stress tolerance. In this work, we present for the first time, soybean leaves lipid content modulation in several drought stress levels, highlighting the involvement of phospholipases A. Moreover, a comprehensive analysis of the phospholipase A superfamily was performed, where 53 coding genes were identified and 7 were selected to gene expression analysis in order to elucidate their role in soybean lipid modulation under water deficit. Proportionally to the drought severity, our results revealed that galactolipids relative abundance and their content in linolenic acid decrease. At the same time an accumulation of neutral lipids, mainly due to triacylglycerol content increase, as well as their content in linolenic acid, is observed. Overall, PLA gene expression regulation and lipid modulation corroborate the hypothesis that phospholipases A may be channelling the plastidial fatty acids into extraplastidial lipids leading to a drought-induced accumulation of triacylglycerol in soybean leaves, a key feature to cope with water stress. • Soybean leaf total membrane lipid content is altered by drought stress. • TAG accumulation under water stress. • PLA genes' expression is highly regulated in response to drought. [ABSTRACT FROM AUTHOR]

Highlights • Photochemical and biochemical features assessed as biomarkers of heat wave stress. • Marine diatom species Phaeodactylum tricornutum used as model biomonitor. • Photosynthetic parameters, pigment and fatty acid profiles were efficient biomarkers. • Biomarkers highlighted harmful effects of heat waves on P. tricornutum. • Nutritional value and water oxygenation decrease with impacts on marine food webs. Abstract Global warming is increasing the frequency and intensity of extreme thermal events, with inevitable consequences for marine ecosystems and organisms. Phytoplankton is at the base of marine food webs and diatoms are major contributors to global primary production. Therefore, environmental changes, such as heat, influencing growth, physiology and biochemical composition of diatoms, impact other organisms at higher trophic levels. The model diatom Phaeodactylum tricornutum , particularly rich in the long chain omega-3 eicosapentaenoic acid (EPA), and able to accumulate substantial amounts of storage lipids, has recently been the object of numerous works, regarding fundamental aspects of lipid metabolism and exploring its biotechnological potential for biodiesel and aquaculture purposes. The aim of this study was to use P. tricornutum , growing under controlled conditions, to examine the effects of a heat wave, in order to identify heat stress biomarkers. The photosynthetic and respiratory metabolism was investigated by Chlorophyll a fluorescence and by O 2 evolution and discussed in connection with changes observed in the composition of photosynthetic pigments and fatty acids. Phaeodactylum tricornutum cells exposed to 26 °C displayed lower photosynthetic O 2 production, but similar respiratory rate, comparing to cells at control temperature (18 °C), which is likely related to the biomass decrease observed under heat stress. Heat wave exposed cells also showed a less efficient PSII, higher energy dissipation and higher chlorophyll a and fucoxanthin concentrations, suggesting a heat-induced amplification of the light energy absorption capacity. Heat wave exposed cells showed lower relative EPA contents and double bond indexes, whereas the parameter inversely related to nutritional value, omega 6/omega 3 ratio, increased. Moreover, the analysis of the fatty acid profiles also suggested that heat exposure negatively impacted thylakoid lipids, in agreement with the decrease observed in photosynthesis. Results obtained highlight the negative impact of heat waves on diatom photosynthesis and nutritional value, as well as on their capacity to oxygenate ocean water. Furthermore, physiological parameters as well as fatty acids and photosynthetic pigments signatures, were identified, that could represent expedite biomarkers of thermal stress in future studies. [ABSTRACT FROM AUTHOR]

Estuarine 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. fruticosa 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. [ABSTRACT FROM AUTHOR]

Grapevine is susceptible to several diseases, being downy mildew, caused by Plasmopara viticola, among the most devastating. Control strategies include the application of pesticides every season through almost all the grapevine developmental stages, jeopardizing viticulture sustainability. Understanding resistance molecular processes is crucial to define alternative strategies and select disease resistance traits. Identifying markers that discriminate between tolerant and susceptible genotypes to P. viticola is an important step. It is shown that lipids and fatty acids (FA) play an important role in grapevine defence against downy mildew and in our previous works we have highlighted that susceptible and resistant grapevine genotypes present contrasting FA profiles even without infection. Here, the constitutive lipid and FA composition of four grapevine genotypes, with contrasting behaviour toward P. viticola was analysed. FA desaturases (FAD) gene expression was also analysed. The results indicate that the susceptible genotypes present higher content of plastidial lipids and unsaturated FA and higher expression levels of FAD genes, whereas tolerant genotypes have higher amounts of neutral lipids and phosphatidic acid as well as saturated FA. In this preliminary study, the concentration of monogalactosyldiacylglycerol and phosphatidylcholine was pinpointed as potential tolerance-associated biomarkers and both linoleic acid and plastidial lipids as susceptibility-associated biomarkers. • Lipids and fatty acid desaturase genes are grapevine tolerance/susceptibility markers to Plasmopara viticola. • Susceptible genotypes have higher plastid lipids, unsaturated fatty acids and fatty acid desaturase expression levels. • Tolerant genotypes have higher neutral lipids, phosphatidic acid and saturated fatty acid amounts. [ABSTRACT FROM AUTHOR]

Quinoa consumption has increased in worldwide importance due to an extraordinary nutritional value and public acceptance as alternative food. Fatty acid profiles of 10 quinoa varieties grown in the same geographical location were analyzed using different chemometric multivariate approaches [variable in importance partial least square discriminant analysis (VIP-PLS-DA), stepwise linear discriminant analysis (S-LDA), linear discriminant analysis (LDA), random forests (RF) and canonical analysis of principal components (CAP)]. The application of variable selection approaches such as S-LDA and LDA significantly increased the classification accuracy (78% and 74% respectively) of the samples according to their variety. The S-LDA approach allowed to reduce the number of selected fatty acids, representing those fatty acids with higher statistical significance when applying other random and non-random approaches. These fatty acid profiles also allowed the estimation of the nutritional lipid profiles of each variety for suitability in the human diet, providing insights into the various nutritional qualities of each quinoa variety. It is proposed that these results can be used to facilitate the selection of varieties with optimized economic value. • Different quinoa varieties display different fatty acid (FA) signatures. • Different FA profiles leads to different cultivar nutritional characteristics. • Stepwise Linear Discriminant Analysis (S-LDA) showed a 78% classification accuracy. • S-LDA allowed a reduction of FA traits to those with high statistical significance. [ABSTRACT FROM AUTHOR]

• Diatom fatty acids (FA) are affected by the applied xenobiotic type and concentration. • C14:0 and C16:0 FAs showed a transversal increase to all exposures tested. • Some contaminants induced specific changes in the diatoms FAs. • FA multivariate analysis revealed a high accuracy in separating different treatments. • The LipidTOX index is correlated with the xenobiotic concentration applied. 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. [ABSTRACT FROM AUTHOR]

Recent global changes have contributed to water scarcity and land degradation, urging for the development of alternative solutions in agriculture. Halophytes biosaline agriculture has been viewed in the past decades as a potential alternative to traditional agriculture practices in degraded lands and salinized soils. Abandoned salt pans provide ideal areas for halophyte cultivation, such as Halimione portulacoides (sea purslane), Sarcocornia fruticosa (shrubby swampfire), Atriplex halimus (sea orache), Beta maritima (sea beet), Inula crithmoides (golden samphire) and Suaeda vera (shrubby seablite). The use of a natural irrigation scheme with estuarine water for food production is a rather novel practice in the Mediterranean area. In the present work, we evaluate the nutritional value of these six halophytes cultivated in abandoned salt pans, irrigated with natural estuarine water. The halophytes produced under this cultivation scheme resulted in vegetable products with a high nutritional value. These edible halophyte presented low sugar content and high protein, omega-3 fatty acids and β-cryptoxanthin contents, together with a valuable source of highly concentrated phenolic and flavonoid anti-oxidant molecules. Moreover, these halophytes provide several mineral elements which are normally scarce in modern human diets (e.g. iodine and selenium), and very low concentrations, below the maximum thresholds, of carcinogenic elements. When compared to traditional vegetables, such as spinach, halophytes presented a high nutritional value, reinforcing the application of these cultivation schemes as means to attain highly nutritive alternative vegetable sources for a healthier human diet. • Halophyte's agriculture is an alternative to traditional agriculture for degraded soils. • The halophytes produced in abandoned saltpans have high nutritional value. • These vegetables are rich in omega-3 and -6 fatty acids and β-cryptoxanthine. • These halophytes provide mineral elements normally scarce in modern human diets (e.g. I and Se). • Additionally, they present low concentrations, below the maximum thresholds, of carcinogenic elements. [ABSTRACT FROM AUTHOR]

Dwarf eelgrass Zostera noltii meadows are found in estuarine coastal areas across the north-eastern Atlantic, where they provide key ecosystem services, including nursery grounds, sediment stabilization, nutrient cycling and carbon sequestration. These blue carbon ecosystems are being subjected to several anthropogenic pressures, including climate change-related effects. In the present study, we investigated the biochemical changes (fatty acid profiling) under different climate change scenarios (present-day conditions, ocean acidification, ocean warming and combined warming and acidification), following IPCC RCP scenario 8.5. Significant modifications in the percentage of saturated (SFA) and polyunsaturated fatty acids (PUFAs) in response to warming and low pH levels were detected. The changes suggest a rearrangement of membrane composition to maintain membrane fluidity, especially under warming conditions. Individuals under warming treatment showed higher plastidial pathway activity, while acidification induced a shift in the fatty acid synthesis pathway towards the extra-plastidial pathway, indicating a need to readjust the chloroplastidial monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) lipids under thermal stress to counteract excessive membrane fluidity. Regarding PUFA fatty acids, α-linolenic acid (ALA, C18:3, n-3) showed a pronounced decrease under the combined treatment, a tendency that can be connected to reactive oxygen species (ROS) quenching and membrane remodelling. Thus, and observing the changes in the fatty acid profile, these essential molecules appear as good candidate biomarkers to detect changes in seagrass ecophysiology under acute climate change-related events. Our findings suggest that future global warming will pose a serious threat to these already endangered blue ecosystems. • Seagrasses are marine founding species threatened by climate change. • These plants are sources of essential fatty acids (FAs) for the marine heterotrophic life. • Leaf saturated and polyunsaturated FAs in response to warming and acidification. • Linolenic acid decrease appears to be connected to reactive oxygen species quenching. • Seagrass FAs profile appear as good candidate biomarkers for climate change related stress. [ABSTRACT FROM AUTHOR]

Emerging pollutants such as pharmaceuticals are continuously released to aquatic environments posing a rising threat to marine ecosystems. Yet, monitoring routines and ecotoxicity data on biota worldwide for these substances are lacking. Non-steroidal anti-inflammatory drugs are among the most prescribed and found pharmaceuticals in aquatic environments. The toxicity effects of environmentally relevant concentrations of ibuprofen on primary productivity, oxidative stress and lipid metabolism of the diatom Phaeodactylum tricornutum were assessed. Diatom cultures were exposed to 0, 0.8, 3, 40, 100 and 300 μg L−1 ibuprofen concentrations, usually found in the vicinity of wastewater treatment plants and coastal environments. Higher concentrations (100 and 300 μg L−1) had a negative impact in P. triconutum growth, inhibiting the chloroplastic energy transduction in the electron transport chain resulting in lower energy reaching the PS I (r2 = −0.55, p < 0.05). In contrast, the mitochondrial electron transport and available energy increased (r2 = 0.68 and r2 = 0.85, p < 0.05 respectively), mostly due to enhancements in lipid and protein contents as opposed to reduction of carbohydrates. A general up-regulation of the antioxidant enzymes could contributed to alleviate oxidative stress resulting in the decrease of lipid peroxidation products (r2 = 0.77, p < 0.05). Canonical analysis of principal components was performed and successfully discriminated exposure groups, with optical data excelling in classifying samples to different ibuprofen concentrations, being potentially used as environmental indicators. Finally, the identified mild to severe effects of ibuprofen on diatoms are likely to be exacerbated by the sustained use of this drug worldwide, underpinning the urgency of evaluating the impacts of this pharmaceutical on coastal and marine trophic webs. • Higher concentrations of Ibuprofen had a severe impact on P. tricornutum growth. • Ibuprofen provoked impairments in PS II by inhibiting the chloroplastic energy transduction in the electron transport chain. • Alteration of lipid content and peroxidation resulting in the rise of membrane fluidity and damage were detected. • Mitochondrial electron transport and available energy were enhanced. • Bio-optical tools emerge as efficient non-invasive techniques for ecotoxicology. [ABSTRACT FROM AUTHOR]