How the Ethylene Biosynthesis Pathway of Semi-Halophytes Is Modified with Prolonged Salinity Stress Occurrence?

The mechanism of ethylene (ET)-regulated salinity stress response remains largely unexplained, especially for semi-halophytes and halophytes. Here, we present the results of the multifaceted analysis of the model semi-halophyte L. (common ice plant) ET biosynthesis pathway key components' response to prolonged (14 days) salinity stress.

Plasticity of L. in Adaptation to Extreme Environmental Conditions.

This study aimed at characterizing some adaptive changes in L. exposed to harsh conditions of a desert-like environment generating physiological stress of limited water availability and exposure to strong light. It was clearly shown that the plants were capable of adapting their root system and vascular tissues to enable efficient vegetative performance.

Cadmium-Tolerant Rhizospheric Bacteria of the C/CAM Intermediate Semi-Halophytic Common Ice Plant ( L.) Grown in Contaminated Soils.

The common ice plant, L., has recently been found as a good candidate for phytoremediation of heavy-metal polluted soils. This semi-halophyte is a C/CAM (Crassulacean acid metabolism) intermediate plant capable of tolerating extreme levels of cadmium in the soil.

ROS-Scavengers, Osmoprotectants and Violaxanthin De-Epoxidation in Salt-Stressed with Different Tocopherol Composition.

To determine the role of α- and γ-tocopherol (TC), this study compared the response to salt stress (200 mM NaCl) in wild type (WT) (L.) Heynh. And its two mutants: (1) totally TC-deficient ; (2) accumulating γ-TC instead of α-TC; and (3) transgenic line overaccumulating α-TC.

At the Edges of Photosynthetic Metabolic Plasticity-On the Rapidity and Extent of Changes Accompanying Salinity Stress-Induced CAM Photosynthesis Withdrawal.

The common ice plant ( L.) is a facultative crassulacean acid metabolism (CAM) plant, and its ability to recover from stress-induced CAM has been confirmed. We analysed the photosynthetic metabolism of this plant during the 72-h response period following salinity stress removal from three perspectives.

Exogenous Methyl Jasmonate Improves Cold Tolerance with Parallel Induction of Two Cold-Regulated () Genes Expression in L.

Methyl jasmonate (MJ) is an important plant growth regulator that plays a key role in tolerance to biotic and abiotic stresses. In this research, the effects of exogenous MJ on cold tolerance, photosynthesis, activity and gene expression of antioxidant enzymes, proline accumulation, and expression of cold-regulated () genes in wheat seedlings under low temperature (4 °C) were investigated. Exogenous MJ treatment (1 µM) promoted wheat cold tolerance before and during cold exposure.

Cooling effect of fungal stromata in the symbiosis.

The stromata of fungi are structures covering part of the stem of grasses. Under the fungal layer, still green tissues of the plant survive, although the development of the new leaves is inhibited. Stromata are the places where conidia and ascospores develop.

Tocopherols mutual balance is a key player for maintaining Arabidopsis thaliana growth under salt stress.

Enhanced channeling carbon through pathways: shikimate/chorismate, benzenoid-phenylopropanoid or 2-C-methyl-D-erythritol 4-phosphate (MEP) provides a multitude of secondary metabolites and cell wall components and allows plants response to environmental stresses. Through the biosynthetic pathways, different secondary metabolites, like tocopherols (TCs), are bind to mutual dependencies and metabolic loops, that are not yet fully understood. We compared, in parallel, the influence of α- and γ-TCs on metabolites involved in osmoprotective/antioxidative response, and physico-chemical modification of plasma membrane and cell wall.

The Common Ice Plant ( L.)-Phytoremediation Potential for Cadmium and Chromate-Contaminated Soils.

The common ice plant ( L.) is a widely studied model due to its tolerance to numerous biotic and abiotic stresses. In this study, carried out in model pots, the plants were treated with variant doses of Cd(II) and Cr(VI) and proved resistant to extreme levels of these heavy metals.

Antioxidative action of polyamines in protection of phospholipid membranes exposed to ozone stress.

In the present work, Langmuir monolayers were used to study the interaction of putrescine (a cationic antioxidant) with anionic charged membranes (1,2-dioleoyl-sn-glycerol-3-phosphate) under oxidative stress caused by the presence of ozone in the water phase. Calcium ions and acidic environment were used to compare the electrostatic and antioxidant effects of putrescine with those of an inorganic cation. It has been shown that the main role of putrescine in protecting systems against oxidation is its rapid reaction with ROS.

Expression of Genes Involved in Heavy Metal Trafficking in Plants Exposed to Salinity Stress and Elevated Cd Concentrations.

Many areas intended for crop production suffer from the concomitant occurrence of heavy metal pollution and elevated salinity; therefore, halophytes seem to represent a promising perspective for the bioremediation of contaminated soils. In this study, the influence of Cd treatment (0.01-10.

The response of a model C/CAM intermediate semi-halophyte Mesembryanthemum crystallinum L. to elevated cadmium concentrations.

Many areas exhibiting increased concentrations of soluble salts are simultaneously polluted with heavy metals (HM), and halophytes with extended tolerance to heavy metal toxicity seem to represent a promising tool for their phytoremediation. In this study, the response of the soil-grown C-CAM (Crassulacean acid metabolism) intermediate halophyte Mesembryanthemum crystallinum (common ice plant) to increased concentrations of Cd (0.01-1 mM) was investigated.

How to define obligatory anaerobiosis? An evolutionary view on the antioxidant response system and the early stages of the evolution of life on Earth.

One of the former definitions of "obligate anaerobiosis" was based on three main criteria: 1) it occurs in organisms, so-called obligate anaerobes, which live in environments without oxygen (O), 2) O-dependent (aerobic) respiration, and 3) antioxidant enzymes are absent in obligate anaerobes. In contrast, aerobes need O in order to grow and develop properly. Obligate (or strict) anaerobes belong to prokaryotic microorganisms from two domains, Bacteria and Archaea.

Spatial referencing of chlorophyll fluorescence images for quantitative assessment of infection propagation in leaves demonstrated on the ice plant: pathosystem.

Background: Chlorophyll fluorescence analysis is one of the non-invasive techniques widely used to detect and quantify the stress-induced changes in the photosynthetic apparatus. Quantitative information is obtained as a series of images and the specific fluorescence parameters are evaluated inside the regions of interest outlined separately on each leaf image. As the performance of photosynthesis is highly heterogeneous over a leaf surface, the areas of interest selected for generating numeric data are crucial for a reliable analysis.

Withdrawal from functional Crassulacean acid metabolism (CAM) is accompanied by changes in both gene expression and activity of antioxidative enzymes.

In Mesembryanthemum crystallinum, crassulacean acid metabolism (CAM) is seemingly reversible, but unequivocal evidence for functional CAM withdrawal has yet to be shown. In this study, we confirmed the rapid downregulation of PEPC1 expression just 1 h after the removal of NaCl from the plant growth media. At the same time, the Δ malate values in desalted plants rapidly (1 d) re-established to values typical for C plants.

Foliar application of selenium for protection against the first stages of mycotoxin infection of crop plant leaves.

Background: The aim of this study was to investigate whether the application of selenium (Se) ions directly to the leaf surface can protect plants against infection by the fungal toxin zearalenone (ZEA). The experiments were performed for the most common and agronomically important crops such as wheat, oat, and barley (both tolerant and sensitive varieties) because mycotoxin accumulation in plants is the cause of many diseases in animals and people.

Results: ZEA at a concentration of 10 µmol L either alone or in combination with Se (5 µmol L Na SeO ) was applied to the second leaf of seedlings.

Seasonal variations of leaf chlorophyll-protein complexes in the wintergreen herbaceous plant Ajuga reptans L.

The chlorophyll and carotenoid content, and the spectra of low-temperature fluorescence of the leaves, chloroplasts and isolated pigment-protein complexes in the perennial herbaceous wintergreen plant Ajuga reptans L. (bugle) in different seasons of the year were studied. During winter, these plants downregulate photosynthesis and the PSA is reorganised, including the loss of chlorophyll, possible reductions in the number of functional reaction centres of PSII, and changes in aggregation of the thylakoid protein complexes.

Photosynthetic activity of vascular bundles in Plantago media leaves.

Photosynthetic processes in the leaf lamina and midribs of Plantago media were investigated using plants grown in high light (HL) or low light (LL) conditions. The fluorescence parameters, which indicate photochemical/photosynthetic activity, were different in HL and LL grown plants, but no major differences between lamina and midribs were found. An OJIP test (chlorophyll a fluorescence transient induction) of LL grown plants, indicative of the chloroplast electron transport chain, also showed both tissues to be similar.

Effects of exogenously applied hydrogen peroxide on antioxidant and osmoprotectant profiles and the C3-CAM shift in the halophyte Mesembryanthemum crystallinum L.

Exogenously applied H2O2 (50, 100 and 200mM) to Mesembryanthemum crystallinum root medium induced a transition from C3 to Crassulacean Acid Metabolism (CAM), as evaluated by diurnal malate (Δmal) fluctuations. A very high concentration of H2O2 (400mM) reduced Δmal below the value measured in control plants. An increase of malate content during the night in 400mM H2O2-treated plants might suggest that malate decarboxylation is crucial for CAM functioning.

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3-CAM intermediate plant Mesembryanthemum crystallinum.

Background And Aims: Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis.

Veinal-mesophyll interaction under biotic stress.

According to microscopic observations, germinating hyphae of Botrytis cinerea, though easily penetrating Mesembryanthemum crystallinum mesophyll tissue, are limited in growth in mid-ribs and only occasionally reach vascular bundles. In mid-ribs of C3 and CAM leaves, we found significantly lower rbcL (large RubisCO subunit) abundance. Moreover, in CAM leaves, minute transcript contents for pepc1 (phosphoenolpyruvate carboxylase) and nadpme1 (malic enzyme) genes found in the mid-ribs suggest that they perform β-carboxylation at a low rate.

Plastoquinone redox state modifies plant response to pathogen.

The role of PQ (plastoquinione) redox state in establishment of response to pathogen infection (Botrytis cinerea) was tested along the regulation of main antioxidative enzymes (superoxide dismutase - SOD, catalase - CAT) and photochemistry of PSII (photosystem II) in Mesembryanthemum crystallinum plants performing C3 and CAM (Crassulacean acid metabolism) carbon metabolism. The redox state of PQ was modified by two inhibitors of photosynthetic electron transport resulting in a more oxidised (3-(3,4-dichlorophenyl)-1,1-dimethylurea; DCMU) or reduced (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone; DBMIB) PQ redox state simulating darkness and high light conditions, respectively. Irrespective of the type of treatment (mock inoculation or pathogen inoculation) SOD activity depended on the PQ pool.

Ozone fumigation increases the abundance of nutrients in vegetables: broccoli ( var. and Chinese cabbage ().

vegetables, among them broccoli and Chinese cabbage, are well recognized due to the nutritional properties. Four-week-old Chinese cabbage and broccoli seedlings were fumigated with O for 3 days before being transplanted into the field. The effect of O treatment was determined after reaching marketable quality (ca.

The localization of NADPH oxidase and reactive oxygen species in in vitro-cultured Mesembryanthemum crystallinum L. hypocotyls discloses their differing roles in rhizogenesis.

This work demonstrated how reactive oxygen species (ROS) are involved in the regulation of rhizogenesis from hypocotyls of Mesembryanthemum crystallinum L. cultured on a medium containing 1-naphthaleneacetic acid (NAA). The increase of NADPH oxidase activity was correlated with an increase of hydrogen peroxide (H2O2) content and induction of mitotic activity in vascular cylinder cells, leading to root formation from cultured hypocotyls.

Pattern of antioxidant enzyme activities and hydrogen peroxide content during developmental stages of rhizogenesis from hypocotyl explants of Mesembryanthemum crystallinum L.

H2O2 is necessary to elicit rhizogenic action of auxin. Activities of specific catalase and manganese superoxide dismutase forms mark roots development. Hypocotyl explants of Mesembryanthemum crystallinum regenerated roots on medium containing 2,4-dichlorophenoxyacetic acid.