Differential Antioxidant Response to Supplemental UV-B Irradiation and Sunlight in Three Basil Varieties.

Three basil plant varieties ( var. Genovese, × , and var. ) were grown under moderate light (about 300 µmol photons m s) in a glasshouse or growth chamber and then either transferred to an open field (average daily dose: 29.

Red-Light Transmittance Changes in Variegated -Diurnal Variation in Chloroplast Movement and Photosystem II Efficiency.

Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark-light transitions.

Differential Response of Two Tomato Genotypes, Wild Type cv. Ailsa Craig and Its ABA-Deficient Mutant to Short-Termed Drought Cycles.

Two tomato genotypes with constitutively different ABA level, mutant and wild type of Ailsa Craig cv. (WT), were subjected to three repeated drought cycles, with the aim to reveal the role of the abscisic acid (ABA) threshold in developing drought tolerance. Differential responses to drought of two genotypes were obtained: more pronounced stomatal closure, ABA biosynthesis and proline accumulation in WT compared to the mutant were compensated by dry weight accumulation accompanied by transient redox disbalance in .

Oxidative Stress and Antioxidative Activity in Leaves and Roots of Carrot Plants Induced by Phytoplasma Solani.

The present study examined the effects of Phytoplasma solani infection on antioxidative metabolism in leaves and roots of carrot ( L.). Disease symptoms appeared at the end of June in the form of the chlorosis on some of the leaves, which became intensely red one week later, while the previously healthy leaves from the same branch becme chlorotic.

Efficient protein extraction for shotgun proteomics from hydrated and desiccated leaves of resurrection Ramonda serbica plants.

Resurrection plant Ramonda serbica is a suitable model to investigate vegetative desiccation tolerance. However, the detailed study of these mechanisms at the protein level is hampered by the severe tissue water loss, high amount of phenolics and polysaccharide, and possible protein modifications and aggregations during the extraction and purification steps. When applied to R.

Silencing of ascorbate oxidase results in reduced growth, altered ascorbic acid levels and ripening pattern in melon fruit.

Ascorbate oxidase (AO, EC 1.10.3.

Leaf Soluble Sugars and Free Amino Acids as Important Components of Abscisic Acid-Mediated Drought Response in Tomato.

Water deficit has a global impact on plant growth and crop yield. Climate changes are going to increase the intensity, duration and frequency of severe droughts, particularly in southern and south-eastern Europe, elevating the water scarcity issues. We aimed to assess the contribution of endogenous abscisic acid (ABA) in the protective mechanisms against water deficit, including stomatal conductance, relative water potential and the accumulation of osmoprotectants, as well as on growth parameters.

Molecular Characterization of pv. and Biochemical Changes Attributable to the Pathological Response on Its Hosts Carrot, Parsley, and Parsnip.

Bacterial leaf spot caused by the plant pathogenic bacterium pv. () was observed on carrot, parsnip, and parsley grown on a vegetable farm in the Vojvodina Province of Serbia. Nonfluorescent bacterial colonies were isolated from diseased leaves and characterized using different molecular techniques.

Resource allocation in response to herbivory and gall formation in Linaria vulgaris.

Trehalose and its precursor, trehalose 6-phosphate (T6P), are essential regulators of plant response to abiotic and biotic stress. Here we used the specific host-insect interaction between Linaria vulgaris (Plantaginaceae) and stem-galling weevil, Rhinusa pilosa (Mecinini, Curculionidae) with the aim to distinguish carbohydrate allocation patterns in response to herbivory, gall formation (G1, 24 h after oviposition), and gall development (G2, 7 days after oviposition) under controlled conditions. The hypothesis is that herbivory and galling induce distinct responses in both leaves and stems, and that shifts in carbon allocations are regulated by signaling sugars.

Biomonitoring of Urban Pollution Using Silicon-Accumulating Species, Phyllostachys aureosulcata 'Aureocaulis'.

We investigated metal accumulation in bamboo leaves during three seasons at three urban locations differing in pollution levels. The higher content of Cu, Pb, and Zn in the leaves was in correlation with the highest bioavailable content of these elements in the soil at the most polluted location. The content of leaf trace elements was higher in summer and autumn compared to spring.

Physiological basis of differential zinc and copper tolerance of Verbascum populations from metal-contaminated and uncontaminated areas.

Metal contamination represents a strong selective pressure favoring tolerant genotypes and leading to differentiation between plant populations. We investigated the adaptive capacity of early-colonizer species of Verbascum recently exposed to Zn- and Cu-contaminated soils (10-20 years). Two Verbascum thapsus L.

Characterisation of antioxidants in photosynthetic and non-photosynthetic leaf tissues of variegated Pelargonium zonale plants.

Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions.

Formation of stable radicals in catechin/nitrous acid systems: participation of dinitrosocatechin.

Catechins are transformed into dinitrosocatechins (diNOcats) and then oxidized to the quinones by salivary nitrite under conditions simulating the stomach. This manuscript deals with formation of stable radicals in the NO group of diNOcat during nitrite-induced oxidation of (+)-catechin and diNOcat at pH 2. We postulated two mechanisms for the stable radical formation; one is nitrous acid-induced oxidation of diNOcat in the A-ring, and the other intermolecular charge transfer from the A-ring of diNOcat and/or diNOcat quinone to the quinone moiety of the B-ring of diNOcat quinone.

Quercetin 7-O-glucoside suppresses nitrite-induced formation of dinitrosocatechins and their quinones in catechin/nitrite systems under stomach simulating conditions.

Foods of plant origin contain flavonoids. In the adzuki bean, (+)-catechin, quercetin 3-O-rutinoside (rutin), and quercetin 7-O-β-D-glucopyranoside (Q7G) are the major flavonoids. During mastication of foods prepared from the adzuki bean, the flavonoids are mixed with saliva and swallowed into the stomach.

Ultraviolet-B component of sunlight stimulates photosynthesis and flavonoid accumulation in variegated Plectranthus coleoides leaves depending on background light.

We used variegated Plectranthus coleoides as a model plant with the aim of clarifying whether the effects of realistic ultraviolet-B (UV-B) doses on phenolic metabolism in leaves are mediated by photosynthesis. Plants were exposed to UV-B radiation (0.90 W m(-2) ) combined with two photosynthetically active radiation (PAR) intensities [395 and 1350 μmol m(-2)  s(-1) , low light (LL) and high light (HL)] for 9 d in sun simulators.

Interactions between (+)-catechin and quercetin during their oxidation by nitrite under the conditions simulating the stomach.

When foods that contain catechins and quercetin glycosides are ingested, quercetin glycosides are hydrolyzed to quercetin during mastication by hydrolytic enzymes derived from oral bacteria and the generated quercetin aglycone is mixed with catechins in saliva. The present study deals with the interactions between (+)-catechin and quercetin during their reactions with nitrous acid under the conditions simulating the gastric lumen. Nitrous acid reacted with (+)-catechin producing 6,8-dinitrosocatechin, and quercetin partially suppressed the dinitrosocatechin formation.

Biochemical and quantitative proteomics investigations in Arabidopsis ggt1 mutant leaves reveal a role for the gamma-glutamyl cycle in plant's adaptation to environment.

The existence of a gamma-glutamyl cycle consisting of intracellular GSH synthesis, extrusion to the apoplastic space and recovery by gamma-glutamyl transferase (GGT)-assisted degradation into its constituent amino acids, has been demonstrated in plants. To address the significance of this cycle in plant cells, we performed integrated biochemical, immunocytochemical, and quantitative proteomics analyses in the Arabidopsis thaliana ggt1 knockout mutant (lacking apoplastic GGT1 isoform) and its corresponding wild-type (WT). The ggt1 knockout leaves exhibited an increased ascorbate and GSH content, increased apoplastic GSH content, and enhanced protein carbonylations in the low-molecular weight range compared to WT.

UV responses of Lolium perenne raised along a latitudinal gradient across Europe: a filtration study.

Lolium perenne (cv. AberDart) was grown at 14 locations along a latitudinal gradient across Europe (37-68°N) to study the impact of ultraviolet radiation (UV) and climate on aboveground growth and foliar UV-B absorbing compounds. At each location, plants were grown outdoors for 5 weeks in a replicated UV-B filtration experiment consisting of open, UV-B transparent (cellulose diacetate) and UV-B opaque (polyester) environments.

The effects of manganese and copper in vitro and in vivo on peroxidase catalytic cycles.

Here we present the results of in vitro and in vivo studies of the influence of Mn²+ and Cu²+ on the peroxidative and oxidative catalytic functions of class III peroxidase. Complex peroxidase catalysis by intermediates generated in the reaction was analyzed by utilizing the activating effect of Mn²+ and the inhibitory effect of Cu²+ on the oxidative reaction in vitro. p-Coumaric acid was used as an enzyme substrate in the peroxidative reaction and as a cofactor in the oxidative reaction.

Zinc-induced oxidative stress in Verbascum thapsus is caused by an accumulation of reactive oxygen species and quinhydrone in the cell wall.

Oxidative stress is one aspect of metal toxicity. Zinc, although unable to perform univalent oxido-reduction reactions, can induce the oxidative damage of cellular components and alter antioxidative systems. Verbascum thapsus L.

Characterisation of phenol oxidase and peroxidase from maize silk.

Silk of some maize genotypes contains a high level of phenolics that undergo enzymatic oxidation to form quinones, which condense among themselves or with proteins to form brown pigments. Two phenolic oxidizing enzymes, peroxidase (POD; EC 1.11.

Characterization of polyphenol oxidase changes induced by desiccation of Ramonda serbica leaves.

Resurrection plants are able to dehydrate/rehydrate rapidly without cell damage by a mechanism, the understanding of which may be of ecological importance in the adaptation of crop plants to dry conditions. The o-diphenol oxidase in Ramonda serbica Pan. & Petrov, a rare resurrection plant of the Balkan Peninsula, was characterized in respect to different isoforms, preferable substrates and specific inhibitors.

Characterization of NAD-dependent malate dehydrogenases from spinach leaves.

Spinach leaves were used to extract isoforms of NAD-dependent malate dehydrogenase (NAD-MDH) (EC 1.1.1.

Effectiveness of phenoxyl radicals generated by peroxidase/H2O2-catalyzed oxidation of caffeate, ferulate, and p-coumarate in cooxidation of ascorbate and NADH.

The rate of ascorbate and nicotinamide adenine dinucleotide plus hydrogen (NADH) cooxidation (i.e., their nonenzymic oxidation by peroxidase/H2O2-generated phenoxyl radicals of three hydroxycinnamates: caffeate, ferulate and p-coumarate) was studied in vitro.