Mesembryanthemum Crystallinum Research Articles

A Culturomics-Based Bacterial Synthetic Community for Improving Resilience towards Arsenic and Heavy Metals in the Nutraceutical Plant Mesembryanthemum crystallinum.

Plant-growth-promoting bacteria (PGPB) help plants thrive in polluted environments and increase crops yield using fewer inputs. Therefore, the design of tailored biofertilizers is of the utmost importance. The purpose of this work was to test two different bacterial synthetic communities (SynComs) from the microbiome of Mesembryanthemum crystallinum, a moderate halophyte with cosmetic, pharmaceutical, and nutraceutical applications. The SynComs were composed of specific metal-resistant plant-growth-promoting rhizobacteria and endophytes. In addition, the possibility of modulating the accumulation of nutraceutical substances by the synergetic effect of metal stress and inoculation with selected bacteria was tested. One of the SynComs was isolated on standard tryptone soy agar (TSA), whereas the other was isolated following a culturomics approach. For that, a culture medium based on M. crystallinum biomass, called Mesem Agar (MA), was elaborated. Bacteria of three compartments (rhizosphere soil, root endophytes, and shoot endophytes) were isolated on standard TSA and MA media, stablishing two independent collections. All bacteria were tested for PGP properties, secreted enzymatic activities, and resistance towards As, Cd, Cu, and Zn. The three best bacteria from each collection were selected in order to produce two different consortiums (denominated TSA- and MA-SynComs, respectively), whose effect on plant growth and physiology, metal accumulation, and metabolomics was evaluated. Both SynComs, particularly MA, improved plant growth and physiological parameters under stress by a mixture of As, Cd, Cu, and Zn. Regarding metal accumulation, the concentrations of all metals/metalloids in plant tissues were below the threshold for plant metal toxicity, indicating that this plant is able to thrive in polluted soils when assisted by metal/metalloid-resistant SynComs and could be safely used for pharmaceutical purposes. Initial metabolomics analyses depict changes in plant metabolome upon exposure to metal stress and inoculation, suggesting the possibility of modulating the concentration of high-value metabolites. In addition, the usefulness of both SynComs was tested in a crop plant, namely Medicago sativa (alfalfa). The results demonstrate the effectiveness of these biofertilizers in alfalfa, improving plant growth, physiology, and metal accumulation.

Comparative Analysis on Phytochemical Properties, Anti-Oxidative, and Anti-Inflammatory Activities of the Different Organs of the Common Ice Plant Mesembryanthemum crystallinum L.

The ice plant (Mesembryanthemum crystallinum L.) is a type of succulent known to contain various minerals and beneficial compounds and is enriched in compounds exhibiting a diversity of bioactivity. This study aims to determine the potential antioxidant and anti-inflammatory effects of the ice plant by organs (cotyledon, stem, and leaf). The ice plant ethanol extract showed that antioxidant activity, measured by the DPPH radical scavenging ability (51.79 ± 4.18%), and hydroxyl radical scavenging activities (6.57 ± 0.29%) had lower levels than those of control BHT, but had higher antioxidant activity in the leaves of the ice plant, while ABTS+ (58.91 ± 7.23%) and Fe2+ chelating activity (16.89 ± 1.68%) showed high antioxidant activity in the cotyledon. Total polyphenols (115.43 ± 0.47 mg QE/g) and flavonoid contents (1218.07 ± 1.00 mg GAE/g) were notably high in the cotyledon. UHPLC-TOF/HRMS analyses identified 17 polyphenolic compounds of ice plants. The main constituents of the extracts obtained in this study were flavonoids, including their O-glycosides, and compounds not previously described were found. The production of NO as a major indicator of the inflammatory response was found to decrease at 100 and 300 μg/mL (p < 0.05). The levels of the inflammatory cytokines TNF-α in 10 μg/mL (p < 0.05), 50, 100, and 300 μg/mL (p < 0.000); IL-6 in 100 and 300 μg/mL (p < 0.01); and IL-1β in 50, 100 μg/mL (p < 0.01), and 300 μg/mL (p < 0.05) confirmed that the anti-inflammatory effect was exhibited by inhibiting the production of inflammatory cytokines according to the concentration of each organ of the ice plant.

Effect of Plasma Treatment on Ice Plant Germination and Physicochemical Surface Using Dielectric Barrier Discharge

Atmospheric pressure plasma treatment on seeds has recently become a valuable technique to improve germination. This work treated Mesembryanthemum crystallinum (ice plant) seeds by the dielectric barrier discharge (DBD) atmospheric pressure plasma at room temperature. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) indicate that after plasma treatment, the N–H stretching vibration of proteins ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim$</tex-math> </inline-formula> 3340 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-1})$</tex-math> </inline-formula> is introduced into the seed surface, increasing the nitrogen content on the surface of the ice plant. Therefore, the seed germination rate increased significantly by 15.2%. However, prolonged plasma treatment reduces seed germination. Because the operating surrounding temperature increases with the treatment time, the wax on the surface of the seed is evaporated, resulting in a significant increase water uptake of seeds. Excess water uptake hinders oxygen diffusion to the embryo, affecting germination. A feasible mechanism and effects of plasma treatment on ice plants are proposed in this study. DBD plasma-treated ice plants significantly increase germination rates, showing excellent potential in the agricultural field.

Exogenous myo-inositol increases salt tolerance and accelerates CAM induction in the early juvenile stage of the facultative halophyte Mesembryanthemum crystallinum but not in the late juvenile stage.

Mesembryanthemum crystallinum L. (ice plant) develops salt tolerance during the transition from the juvenile to the adult stage through progressive morphological, physiological, biochemical, and molecular changes. Myo-inositol is the precursor for the synthesis of compatible solute D-pinitol and promotes Na+ transport in ice plants. We previously showed that supplying myo-inositol to 9-day-old seedlings alleviates salt damage by coordinating the expression of genes involved in inositol synthesis and transport, affecting osmotic adjustment and the Na/K balance. In this study, we examined the effects of myo-inositol on physiological parameters and inositol-related gene expression in early- and late-stage juvenile plants. The addition of myo-inositol to salt-treated, hydroponically grown late juvenile plants had no significant effects on growth or photosynthesis. In contrast, supplying exogenous myo-inositol to salt-treated early juvenile plants increased leaf biomass, relative water content, and chlorophyll content and improved PSII activity and CO2 assimilation. The treatment combining high salt and myo-inositol synergistically induced the expression of myo-inositol phosphate synthase (INPS), myo-inositol O-methyltransferase (IMT), and inositol transporters (INTs), which modulated root-to-shoot Na/K ratio and increased leaf D-pinitol content. The results indicate that sufficient myo-inositol is a prerequisite for high salt tolerance in ice plant.

Phytoremediation of metal-contaminated bottom sediments by the common ice plant (Mesembryanthemum crystallinum L.) in Poland

PurposeThe aim of the study was to propose a phytoremediation-based approach toward the proper utilization of post-industrial, metal-contaminated bottom sediments. The common ice plant, Mesembryanthemum crystallinum L. (Aizoaceae), an abiotic-stress tolerant, C3/CAM intermediate halophyte, was tested for growth in substrates containing bottom sediments and for biological removal of metal pollutants. In variant tests, the sediments were admixed with non-toxic components to reduce the ecotoxicity hazards and improve growth conditions.Materials and methodsBottom sediment samples were collected from Lake Chechło in the industrial area of Poland. They were amended with universal soil and other materials (sand, lime, plant ash) and then used as growth substrates. After 30-day growth the plant biomass and rhizospheric microbiota population were assessed. The elemental content was determined in the substrate as well as in plant organs with inductively coupled plasma–optical emission spectrometry (ICP-OES). Bioaccumulation factors (BAFs, indicating phytoextraction processes) and root-to-shoot translocation factors (TFs) were calculated for all the metals to trace their behavior upon phytoremediation. Ecotoxicity assessments were performed by using a set of biotests (Phytotoxkit, Ostracodtoxkit F, and Microtox).ResultsM. crystallinum proved its ability to grow under harsh conditions of toxic and poor-quality substrates, while allowing for proliferation of rhizosphere bacteria. The plant growth was accompanied by the accumulation of Na and several other metals which were partially removed from the bottom sediment-containing soils. Depending on the experimental variant, the maximum removal achieved upon the 30-day test was: for Cd, 18.1%, Cu, 47.6%, Cr, 32.7%, Pb, 36.6%, and Zn, 24.1%. M. crystallinum hyperaccumulated Zn and accumulated (either in roots or shoots) Cd, Cu, Cr, and Ni. The maximum BAF values (> 1.0,) were obtained for the following metals: Cd, Cr, Ni, Cu (roots) and Cd, Cr, Ni, Zn (shoots). The highest values of TF (> 1), confirming high phytoremediation potential, were calculated for Na (33.33), Cd (1.47), Cu (1.77), Cr (7.85), and Zn (4.02). Bottom sediments revealed class III toxicity (acute), which was decreased by admixing with other materials. Surprisingly, the treatment with M. crystallinum led to an increase of toxicity levels, possibly by mobilizing potentially toxic elements during plant growth and microbial population development. However, mixing the sediments with universal soil and lime enabled us to maintain class I (no acute toxicity).ConclusionThe common ice plant reveals strong application potential for use in reclamation of soils or revitalization of industrially degraded areas containing bottom sediments.

Ice plant root plasma membrane aquaporins are regulated by clathrin-coated vesicles in response to salt stress.

The regulation of root Plasma membrane (PM) Intrinsic Protein (PIP)-type aquaporins (AQPs) is potentially important for salinity tolerance. However, the molecular and cellular details underlying this process in halophytes remain unclear. Using free-flow electrophoresis and label-free proteomics, we report that the increased abundance of PIPs at the PM of the halophyte ice plant (Mesembryanthemum crystallinum L.) roots under salinity conditions is regulated by clathrin-coated vesicles (CCV). To understand this regulation, we analyzed several components of the M. crystallinum CCV complexes: clathrin light chain (McCLC) and subunits μ1 and μ2 of the adaptor protein (AP) complex (McAP1μ and McAP2μ). Co-localization analyses revealed the association between McPIP1;4 and McAP2μ and between McPIP2;1 and McAP1μ, observations corroborated by mbSUS assays, suggesting that AQP abundance at the PM is under the control of CCV. The ability of McPIP1;4 and McPIP2;1 to form homo- and hetero-oligomers was tested and confirmed, as well as their activity as water channels. Also, we found increased phosphorylation of McPIP2;1 only at the PM in response to salt stress. Our results indicate root PIPs from halophytes might be regulated through CCV trafficking and phosphorylation, impacting their localization, transport activity, and abundance under salinity conditions.

Composition, anti-LDL oxidation, and non-enzymatic glycosylation inhibitory activities of the flavonoids from Mesembryanthemum crystallinum.

This study identified the constituents of purified flavonoid (PEF) isolated from Mesembryanthemum crystallinum and examined their inhibitory effects on low-density lipoprotein (LDL) oxidation and non-enzymatic glycosylation. More than 30 kinds of flavonoid compounds were identified in M. crystallinum, including tangeretin, nobiletin, farrerol, protocatechuic aldehyde, diosmin, and rutin. Moreover, tangeretin corresponds to approximately 51% of the total identified flavonoids. PEF had a low IC50 value for 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH·), hydroxyl radical (·OH), and superoxide anion free radical (O) scavenging. They were found to effectively delay and inhibit the production of conjugated diene (CD) and thiobarbituric acid reactive substance (TBARS) during LDL oxidation. Meanwhile, scanning electron microscopy (SEM) of the LDL oxidation incubation system with PEF showed a smooth and dense surface, with no obvious cavitation phenomenon. Furthermore, PEF effectively inhibited the production of LDL glycosylation products and showed a strong inhibitory effect in the latter stage. The electrophoresis of advanced glycosylation end products (AGEs) further confirmed that PEF can effectively prevent the cross-linking between glucose and proteins, protecting LDL from glycosylation-induced damage.

Sensory Evaluation of Common Ice Plant (Mesembryanthemum crystallinum L.) in Response to Sodium Chloride Concentration in Hydroponic Nutrient Solution.

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible plant with a succulent and savory flavor. The plants display prominent epidermal bladder cells (EBCs) on the surface of the leaves that store water and sodium chloride (NaCl). The plants have high nutritional value and are adapted to saline soils. Previous research has determined the impact of NaCl on the growth and mineral content of ice plant, but as NaCl has an impact on a food’s sensory properties, an interesting question is whether saline growth media can affect the plant’s taste and texture, and if this alters consumers’ sensory response to ice plant. The objective of this study was to evaluate the sensory aspects of ice plant, as well as consumer liking in response to increasing NaCl concentration in hydroponic nutrient solution. Four-week-old seedlings of ice plant were transplanted into deep water culture (DWC) hydroponic systems and treated with five NaCl concentrations (0 M [control], 0.05 M, 0.10 M, 0.20 M, and 0.40 M NaCl). Eight-week-old plants (after four weeks of NaCl treatment) were harvested, and the middle leaves of each plant were sampled for consumer testing. A total of 115 participants evaluated various flavor, texture, and appearance aspects of ice plant and provided their liking ratings. The consumers were able to discriminate differences in salt intensity from the plants based on NaCl treatment in the hydroponic nutrient solution. Low NaCl concentrations (0.05–0.10 M) did not have obvious adverse effect on consumer liking, which aligns with the result of previous research that 0.05–0.10 M NaCl could largely stimulate the growth of ice plant. NaCl concentrations higher than 0.20 M are not recommended from both a production and consumer perspective. With increased NaCl level in plant samples, the consumers detected more saltiness, sourness, and fishiness, less green flavor, and similar levels of bitterness and sweetness. NaCl treatment had no effects on leaf appearance and texture, and the consumers’ overall liking was mainly determined by flavor. Overall, ice plant presents some unique attributes (salty and juicy) compared to other edible salad greens; however, consumer awareness of ice plant is very low, and purchase intent is relatively low as well. Consumers picture ice plant being used mainly in salads and in restaurants.

NaCl–promoted Respiration and Cell Division in Halophilism of a Halophyte, the Common Ice Plant Mesembryanthemum crystallinum L.

NaCl–promoted Respiration and Cell Division in Halophilism of a Halophyte, the Common Ice Plant Mesembryanthemum crystallinum L.

Measurement of Overlapping Leaf Area of Ice Plants Using Digital Image Processing Technique

Non-destructive and destructive leaf area estimation are critical in plant physiological and ecological experiments. In modern agriculture, ubiquitous digital cameras and scanners are primarily replacing traditional leaf area measurements. Thus, measuring the leaflet’s dimension is integral in analysing plant photosynthesis and growth. Leaf dimension assessment with image processing is widely used nowadays. In this investigation employed an image segmentation algorithm to classify the ice plant (Mesembryanthemum crystallinum L.) canopy image with a threshold segmentation technique by grey colour model and calculating the degree of green colour in the HSV (hue, saturation, value) model. Notably, the segmentation technique is used to separate suitable surfaces from a defective noisy background. In this work, the canopy area was measured by pixel number statistics relevant to the known reference area. Furthermore, this paper proposed total leaf area estimation in a destructive method by a computer coordinating area curvimeter and lastly evaluated the overlapping percentage using the total leaf area and canopy area measurements. To assess the overlapping percentage using the proposed algorithm, the curvimeter method experiment was performed on 24 images of ice plants. The obtained results reveal that the overlapping percentage is less than 10%, as evidenced by a difference in the curvimeter and the proposed algorithm’s results with the canopy leaf area approach. Furthermore, the results show a strong correlation between the canopy and total leaf area (R2: 0.99) calculated by our proposed method. This overlapping leaf area finding offers a significant contribution to crop evolution by using computational techniques to make monitoring easier.

Does Plant Identity Affect the Dispersal of Resistomes Above and Below Ground?

Resistomes are ubiquitous in natural environments. Previous studies have shown that both the plant phyllosphere and soil-borne nematodes were reservoirs of above- and below-ground resistomes, respectively. However, the influence of plant identity on soil, nematode, and phyllosphere resistomes remains unclear. Here, a microcosm experiment was used to explore the characteristics of bacterial communities and resistomes in soil, nematode, and phyllosphere associated with six different plant identities (Lactuca sativa, Cichorium endivia, Allium fistulosum, Coriandrum sativum, Raphanus sativus, and Mesembryanthemum crystallinum). A total of 222 antibiotic resistance genes (ARGs) and 7 mobile genetic elements (MGEs) were detected by high-throughput quantitative PCR from all samples. Plant identity not only significantly affected the diversity of resistomes in soil, nematode, and phyllosphere but also influenced the abundance of resistomes in nematodes. Shared bacteria and resistomes indicated a possible pathway of resistomes transfer through the soil-nematode-phyllosphere system. Structural equation models revealed that plant identity had no direct effect on phyllosphere ARGs, but altered indirectly through complex above- and below-ground interactions (soil-plant-nematode trophic transfer). Results also showed that bacteria and MGEs were key factors driving the above- and below-ground flow of resistomes. The study extends our knowledge about the top-down and bottom-up dispersal patterns of resistomes.

High-quality ice plant reference genome analysis provides insights into genome evolution and allows exploration of genes involved in the transition from C3 to CAM pathways.

Ice plant (Mesembryanthemum crystallinum), a member of the Aizoaceae family, is a typical halophyte crop and a model plant for studying the mechanism of transition from C3 photosynthesis to crassulacean acid metabolism (CAM). Here, we report a high-quality chromosome-level ice plant genome sequence. This 98.05% genome sequence is anchored to nine chromosomes, with a total length of 377.97 Mb and an N50 scaffold of 40.45 Mb. Almost half of the genome (48.04%) is composed of repetitive sequences, and 24 234 genes have been annotated. Subsequent to the ancient whole-genome triplication (WGT) that occurred in eudicots, there has been no recent whole-genome duplication (WGD) or WGT in ice plants. However, we detected a novel WGT event that occurred in the same order in Simmondsia chinensis, which was previously overlooked. Our findings revealed that ice plants have undergone chromosome rearrangements and gene removal during evolution. Combined with transcriptome and comparative genomic data and expression verification, we identified several key genes involved in the CAM pathway and constructed a comprehensive network. As the first genome of the Aizoaceae family to be released, this report will provide a rich data resource for comparative and functional genomic studies of Aizoaceae, especially for studies on salt tolerance and C3-to-CAM transitions to improve crop yield and resistance.

Response of Common Ice Plant (Mesembryanthemum crystallinum L.) to Photoperiod/Daily Light Integral in Vertical Hydroponic Production

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible plant with a succulent and savory flavor emerging as new crop for greenhouse and plant factory growers. Currently very limited information is available on the response of ice plant to photoperiod and to daily light integral (DLI). The objective of this study was to determine the impact of photoperiod/DLI on the growth of ice plant for indoor vertical production. Four-week old seedlings of ice plant were transplanted into vertical hydroponic systems and given five photoperiod/DLI treatments: 8/6.3, 12/9.5, 16/12.7, 20/15.8, and 24/19.0 h/mol·m−2·d−1. Sequential destructive harvests to determine plant growth occurred 14, 21, and 28 days after lighting treatments began. Plants performed better with increasing photoperiod/DLI from 8 h/6.3 mol·m−2·d−1 to 20 h/15.8 mol·m−2·d−1. By day 28, shoot fresh weight increased from 160 g to 639 g as the photoperiod/DLI increased from 8 h/6.3 mol·m−2·d−1 to 20 h/15.8 mol·m−2·d−1. The continuous lighting treatment, 24 h/19 mol·m−2·d−1, showed a negative effect on the plant fresh weight (FW) and dry weight (DW). Light treatment did not have obvious effects on shoot:root ratio and macronutrient uptake except that potassium (K) uptake decreased slightly with increased photoperiod/DLI. Plants receiving higher photoperiod/DLI showed the same number of leaves (indicating the same development stage) but had smaller, thicker, and darker green leaves compared to lower photoperiod/DLI treatments. Leaf water content was not affected by light treatment up to 20 h/15.8 mol·m−2·d−1 but decreased at 24 h/19 mol·m−2·d−1. Further research is needed to separate the physiological response of increasing/continuous photoperiod from the response of increasing DLI.

Overexpression of McHB7 Transcription Factor from Mesembryanthemum crystallinum Improves Plant Salt Tolerance.

Mesembryanthemum crystallinum (common ice plant) is one of the facultative halophyte plants, and it serves as a model for investigating the molecular mechanisms underlying its salt stress response and tolerance. Here we cloned one of the homeobox transcription factor (TF) genes, McHB7, from the ice plant, which has 60% similarity with the Arabidopsis AtHB7. Overexpression of the McHB7 in Arabidopsis (OE) showed that the plants had significantly elevated relative water content (RWC), chlorophyll content, superoxide dismutase (SOD), and peroxidase (POD) activities after salt stress treatment. Our proteomic analysis identified 145 proteins to be significantly changed in abundance, and 66 were exclusively increased in the OE plants compared to the wild type (WT). After salt treatment, 979 and 959 metabolites were significantly increased and decreased, respectively, in the OE plants compared to the WT. The results demonstrate that the McHB7 can improve photosynthesis, increase the leaf chlorophyll content, and affect the TCA cycle by regulating metabolites (e.g., pyruvate) and proteins (e.g., citrate synthase). Moreover, McHB7 modulates the expression of stress-related proteins (e.g., superoxide dismutase, dehydroascorbate reductase, and pyrroline-5-carboxylate synthase B) to scavenge reactive oxygen species and enhance plant salt tolerance.

Response of Common Ice Plant (Mesembryanthemum crystallinum L.) to Sodium Chloride Concentration in Hydroponic Nutrient Solution

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible succulent plant with savory flavor. It has epidermal bladder cells (EBCs) that store water and sodium chloride (NaCl) located on the epidermis of the leaves and stems. Ice plant is an obligatory halophyte that requires NaCl for optimum growth. The objective of this study was to determine the impact of NaCl on growth of ice plant for hydroponic production as an edible leafy green and to quantify the ability of ice plant to take up NaCl from the environment. Four-week-old seedlings of ice plant were transplanted into hydroponic systems, established for 1 week, and given five NaCl treatments [0 M (control), 0.05 M, 0.10 M, 0.20 M, 0.40 M NaCl]. Sequential destructive harvests to determine plant growth occurred at day 7, 14, and 21 after NaCl treatment. The 0.05 M NaCl had the greatest stimulating effect on biomass, increasing total fresh weight (FW) by 173% and shoot FW by 193% compared with the control plants. The 0.10 M NaCl also had stimulating effect as compared with 0 M, but plants were not as large as those receiving 0.05 M NaCl. The 0.20 M NaCl had little effect on plant growth compared with the control. The 0.40 M NaCl had a strong stunting effect on plant growth. All plants treated with NaCl had less root weight than the control, and higher NaCl concentration resulted in greater reduction in root weight. However, for the 0.05 and 0.10 M treatment, the gain in shoot weight exceeded the loss in root weight. Plants gained or lost water in a faster rate than dry mass, which resulted in larger differences among treatments in FW than in dry weight (DW). Plants treated with higher NaCl concentrations developed fewer, smaller, and thicker leaves but contained more EBCs per unit leaf surface area. There was high Na and Cl accumulation in leaf tissues of all salt-treated plants (e.g., 180,507 mg·kg−1 Na and 125,084 mg·kg−1 Cl in the 0.05 M treatment vs. 13,558 mg·kg−1 Na and 12,991 mg·kg−1 Cl in the 0 M treatment). This indicated potential for bioremediation of saline soil or hydroponic water. Concentrations of macronutrients such as nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S) were reduced when plants received increasing NaCl treatments. In general, this study showed that growth of ice plant benefited from 0.05 and 0.10 M NaCl additions to the hydroponic nutrient solution. Ice plant deserves further work on its ability to reduce Na and Cl from accumulating in recirculating hydroponic nutrient solution.

Growth and salt accumulation capacity of the common ice plant in the tsunami-affected soil

ABSTRACT Halophytes are salt-tolerant plant that grows naturally in saline areas where almost all conventional crops die due to NaCl toxicity. The common ice plant, Mesembryanthemum crystallinum L., an annual halophyte native to South Africa, tolerates high salinity levels and accumulates NaCl in a shoot at a high level. To check the availability of the ice plant for desalinization of soils, we cultured the ice plant in soils collected from 16 sites located along coastal regions in the prefectures of Miyagi and Iwate, where were attacked by the tsunami disaster in the wake of the 2011 earthquake off the Pacific coast of Tohoku on 11 March 2011. In the soils obtained from some tsunami affected areas, the growth was better than that in the non-contaminated soil. The factors associated with growth inhibition were suggested to be water ratio (an index of water content) and soil water permeability. The ice plant’s estimated biological yield ranged from 0.33 to 14.6 kg m−2, equivalent to 2.3 to 101.7 t ha−1. The sum of Na+ and Cl− was about 9.5 g in the shoot (31.8% on a dry weight basis), and the estimated total amount of these ions removed from salinized soil was 2.38 t ha−1. These results indicated that the common ice plant could be used as a crop under salinity and a tool for ameliorating NaCl from salinized soils.

Assessment of different salt concentrations on the growth and phytochemical change of the ice plants

The ice plant (Mesembryanthemum crystallinum L.) has become a halophyte model to study the plant photosynthetic responses C3 photosynthesis to crassulacean acid metabolism (CAM), which is accelerated by salt stress. However, this adaptive mechanism improves water use efficiency, and water stress tolerance is still poorly known. This study examined the effect of individual and mixture of NaCl and CaCl2 concentrations on morphological parameters and bioactive component contents of ice plants in a plant factory system. Eight salt treatments individually and a combination of sodium chloride (NaCl) and calcium chloride (CaCl2), and Hoagland solutions were applied after the transplanting of ice plants. Morphological parameters like the number of leaves and lateral stems, leaf chlorophyll content (SPAD value), fresh weight, and dry weight of shoots and roots were measured at the adult stage. Concurrently, in the juvenile phase, the area of a canopy was evaluated using an image processing technique in HSV (hue, saturation, value) colour space. Correspondingly, ice plant secondary metabolites such as cations, anions, and radical scavenging activity were assayed in the adult phase correlated to the salt stress. The effects of salt stress on the growth of ice plants and secondary metabolite production were analysed using completely randomized block designs through the variance by one-way ANOVA with a significance level of p < 0.05. This study demonstrated that 400 mM CaCl2 (T4) enhanced the biomass and high sodium (Na+) and calcium (Ca2+) accumulations, and 200 mM CaCl2 (T3) accelerated the potassium (K+), magnesium (Mg2+), phosphate (PO43−), and sulfate (SO42−) accumulations. Moreover, NaCl 400 mM (T1) and combination of 100 mM NaCl and 300 mM CaCl2 (T5) positively influenced the chloride (Cl−) deposition and combination of 200 mM NaCl and 200 mM CaCl2 (T6) improved nitrate (NO3–) accretion. Furthermore, 100 mM CaCl2 (T2) exhibited the highest antioxidant activity in ice plants grown under the plant factory system.

Mesembryanthemum crystallinum L.: A potential invasive plant in Tunisia

Biological invasions are considered as one of the most serious threats to the biodiversity. Mesembryanthemum crystallinum L. (Aizoaceae) is reported invasive in many regions over the world. This paper aim to monitor its distribution in the Kerkennah islands and update its invasive status. Field surveys, performed during May 2022, were achieved to record M. crystallinum occurrences and generate the plant distribution map. Field monitoring reveals that M. crystallinum is widespread and has the ability to grow in a broad range of disturbed habitats. The plant distribution pattern show that it often forms dense stands which allow it to inhibit the growth of other plants. Concidering its behaviour M. crystallinum should be considered as a potential invasive plant in Tunisia which requires the implementation of an appropriate management plan.

Antioxidant, Antihypertensive, Hypoglycaemic and Nootropic Activity of a Polyphenolic Extract from the Halophyte Ice Plant (Mesembryanthemum crystallinum).

This study aims to determine the potential antioxidant, antihypertensive, hypoglycaemic and nootropic activity of a purified polyphenolic extract from the halophyte ice plant (Mesembryanthemum crystallinum). The ice plant extract showed good antioxidant activity measured by DPPH, ORAC, TEAC, FRAP and ferrous ion chelating activity. Moreover, the extract showed potent ACE, DPP-IV and PEP-inhibitory activity (90.5%, 98.6% and 73.1%, respectively, at a final concentration of 1 mg/mL). The extract was fractionated and the fraction with the highest content of total phenolic compounds showed the highest bioactivity, suggesting that polyphenols could be mainly responsible for the abovementioned activities. The tentative polyphenol identification by HPLC-ESI-QTOF-MS in this fraction revealed that flavones (>65%) are the major group, with apigenin (38%) predominating, followed by diosmin (17.7%) and luteolin (11.9%). They could presumably be the main elements responsible for the enzymatic inhibition activity. Additionally, 4-hydroxybenzoic acid, p-coumaric acid and a hydroxycinnamic acid derivative (2-O-(p-cumaroyl)-l-malic acid) were found in the extract. To our knowledge, this is the first time that some of these activities have been reported for halophyte extracts.

Salt stress alters membrane lipid content and lipid biosynthesis pathways in the plasma membrane and tonoplast.

Plant cell membranes are the sites of sensing and initiation of rapid responses to changing environmental factors including salinity stress. Understanding the mechanisms involved in membrane remodeling is important for studying salt tolerance in plants. This task remains challenging in complex tissue due to suboptimal subcellular membrane isolation techniques. Here, we capitalized on the use of a surface charge-based separation method, free flow electrophoresis, to isolate the tonoplast (TP) and plasma membrane (PM) from leaf tissue of the halophyte ice plant (Mesembryanthemum crystallinum L.). Results demonstrated a membrane-specific lipidomic remodeling in this plant under salt conditions, including an increased proportion of bilayer forming lipid phosphatidylcholine in the TP and an increase in nonbilayer forming and negatively charged lipids (phosphatidylethanolamine and phosphatidylserine) in the PM. Quantitative proteomics showed salt-induced changes in proteins involved in fatty acid synthesis and desaturation, glycerolipid, and sterol synthesis, as well as proteins involved in lipid signaling, binding, and trafficking. These results reveal an essential plant mechanism for membrane homeostasis wherein lipidome remodeling in response to salt stress contributes to maintaining the physiological function of individual subcellular compartments.