Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

Physiological, antioxidant and metabolomic responses of Thellungiella salsuginea and Arabidopsis thaliana to moderate salinity-phenanthrene interaction : application to phytoremediation of PAHs by halophytes

La pollution environnementale constitue un problème majeur pour les écosystèmes naturels et la santé publique. Récemment, la phytoremédiation a émergé comme une stratégie innovante, écologique et à faible coût. Elle consiste à utiliser les capacités des plantes à stocker ou/et à dégrader les polluants. Dans cette étude, des analyses physiologiques, biochimiques et métabolomiques, ont permis de montrer que les halophytes, une catégorie des plantes extrêmophiles, présentent une grande capacité à remédier la pollution engendrée par les Hydrocarbures Aromatiques Polycycliques (HAPs). D'autre part, la salinité modérée améliore leur capacité phytoremédiatrice. Ces résultats apportent de nouvelles données pouvant contribuer à l'amélioration de cette stratégie.Halopytes, plants naturally adapted to high salt concentrations, have no clear definition, yet. Their cross-tolerance to abiotic stresses was reviewed in this work at the physiological, biochemical, and molecular levels, with a special emphasis on the mechanisms involved in their cross-tolerance to salinity and organic pollutants that could allow them a higher potential of xenobiotic phytoremediation as compared to glycophytes. In our experimental part, we compared in a first step some physiological and antioxidant responses to phenanthrene as well as its accumulation in the two related model plants Arabidopsis thaliana (glycophyte) and Thellungiella salsuginea (halophyte).In a second step, we investigated the effects of moderate salinity on the responses of the two species to phenanthrene considered as model Polycyclic Aromatic Hydrocarbon (PAH) molecule. Obtained results showed an improvement of phenanthrene-induced responses in the two plants, the effect being more marked in the halophyte. This observation was particularly related to higher antioxidant activities and the induction of more adapted metabolism as several accumulated metabolites are known to be involved in signaling and osmotic adjustment processes. In a final step, we studied the potential of the halophyte Cakile maritima to remediate an inert sand (to avoid the degradation of the pollutant by microorganisms or their interaction with the plant) highly contaminated with phenanthrene

The halophyte Cakile maritima reduces phenanthrene phytotoxicity

International audienceIn a previous study, we showed that the halophyte plant model Thellungiella salsuginea was more tolerant to phenanthrene (Polycyclic Aromatic Hydrocarbon: PAH) than its relative glycophyte Arabidopsis thaliana. In the present work, we investigated the potential of another halophyte with higher biomass production, Cakile maritma, to reduce phenanthrene phytotoxicity. Sand was used instead of arable soil with the aim to avoid pollutant degradation by microorganisms or their interaction with the plant. After 6 weeks of treatment by 500 ppm phenanthrene (Phe), stressed plants showed a severe reduction (-73%) in their whole biomass, roots being more affected than leaves and stems. In parallel, Guaiacol peroxidase (GPX) activity was increased by 185 and 62% in leaves and roots, respectively. Non-enzymatic antioxidant capacity (assayed by ABTS test) was maintained unchanged in all plant organs. The model halophytic plant Thellungiella salsuginea was used as a biomarker of phenanthrene stress severity and was grown at 0 (control), 125, 250, and 375 ppm. T. salsuginea plants grown on the sand previously contaminated by 500 ppm Phe then treated by C. maritma culture (phytoremediation culture) showed similar biomass production as plants subjected to 125 ppm Phe. This suggests that the phytotoxic effects of phenanthrene were reduced by 75% by the 6-week treatment by C. maritima. Our findings indicate that C. maritima can constitute a potentially good candidate for PAH phytoremediation

The halophytic model plant Thellungiella salsuginea exhibited increased tolerance to phenanthrene-induced stress in comparison with the glycophitic one Arabidopsis thaliana: Application for phytoremediation

International audiencePolycyclic aromatic hydrocarbons constitute a large family of organic environmental pollutants. Hence, a particular attention has been attributed to all approaches involved in the reduction of their contamination in water and natural ecosystems. Plant tolerance, absorption, accumulation, and likely biodegradation of these pollutants, known as phytoremediation, have emerged as an efficient technique to remediate environments contaminated with polycyclic aromatic hydrocarbons. The present work was aimed to compare the tolerance to phenanthrene (a polycyclic aromatic hydrocarbon) in the two model plants: Arabidopsis thaliana (glycophyte) and Thellungiella salsuginea (halophyte). Our study showed that the development of these two species was reduced under phenanthrene stress, the effect being more pronounced in A. thaliana than in T. salsuginea. In parallel, results from the intrinsic quantum yield of photosystem II and chlorophyll concentrations were concomitant with those of growth and phenotypic changes, and confirmed the higher tolerance of T. salsuginea compared to that of A. thaliana. The intrinsic quantum yield of photosystem II was drastically decreased in the glycophyte, which indicates a marked disturbance in photosystem II performance. This induced a severe oxidative stress as shown by the utilization of specific reactive oxygen species probes. In parallel, the activities of glutathione reductase, gaiacol peroxidase, and superoxide dismutase were increased by 95, 73, and 36%, respectively, which indicates a marked phenanthrene-induced oxidative stress. In T. salsuginea, photosystem II performance was not significantly affected. This species showed less accumulated reactive oxygen species than A. thaliana. Its enzymatic antioxidant system showed few changes as superoxide dismutase was the only enzyme whose activity was enhanced (+34%). A much higher capacity of recovery was also noticed in this halophyte as compared to the glycophyte. Indeed, it seems that T. salsuginea accumulated phenanthrene in stomata, which suggests its possible volatilization. All these data, taken together, add new insight to the mechanisms involved in halophytic plant tolerance to abiotic stresses and their potential use inphytoremediation

Moderate salinity reduced phenanthrene-induced stress in the halophyte plant model Thellungiella salsuginea compared to its glycophyte relative Arabidopsis thaliana: Cross talk and metabolite profiling

International audienceIt was shown that halophytes experience higher cross-tolerance to stresses than glycophytes, which was often associated with their more powerful antioxidant systems. Moreover, salinity was reported to enhance halophyte tolerance to several stresses. The aim of the present work was to investigate whether a moderate salinity enhances phenanthrene stress tolerance in the halophyte Thellungiella salsuginea. The model plant Arabidopsis thaliana, considered as its glycophyte relative, was used as reference. Our study was based on morpho-physiological, antioxidant, and metabolomic parameters. Results showed that T. salsuginea was more tolerant to phenanthrene stress as compared to A. thaliana. An improvement of phenanthrene-induced responses was recorded in the two plants in the presence of 25 mM NaCl, but the effect was significantly more obvious in the halophyte. This observation was particularly related to the higher antioxidant activities and the induction of more adapted metabolism in the halophyte. Gas Chromatography coupled with Mass Spectrometry (GC-MS) was used to quantify alcohols, ammonium, sugars, and organic acids. It showed the accumulation of several metabolites, many of them are known to be involved in signaling and abiotic stress tolerance. Moderate salinity and phenanthrene cross-tolerance involved in these two stresses was discusse

Transcriptional analysis of phenanthrene treated plants revealed the induction of neoglucogenesis pathway associated with detoxification systems: Possible utilization in phytoremediation strategy

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Comparative responses of halophytic (Thellungiella salsuginea) and glycophitic (Arabidopsis thaliana) plant-models under phenanthrene induced stress: Potential use of halophytic plants in phytoremediation strategies

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Comparative responses of halophytic (Thellungiella salsuginea) and glycophitic (Arabidopsis thaliana) plant-models under phenanthrene induced stress: Potential use of halophytic plants in phytoremediation strategies

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Transcriptional analysis of phenanthrene treated plants revealed the induction of neoglucogenesis pathway associated with detoxification systems: Possible utilization in phytoremediation strategy

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Ecological engineering strategy to clean up wastewater in arid area

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