Possible lessons of a model experiment: To what extent can UV activate the production of leaf phenolics in indoor plant cultivation?

Tobacco (Nicotiana tabacum L.) plants were grown outdoors (N°46.07, E°18.

Phenolic peroxidases: Dull generalists or purposeful specialists in stress responses?

This study focuses on class III peroxidases (POD) (EC 1.11.1.

Phase-Selective Synthesis of Anatase and Rutile TiO Nanocrystals and Their Impacts on Grapevine Leaves: Accumulation of Mineral Nutrients and Triggering the Plant Defense.

Titanium dioxide nanocrystals (TiO NCs), through their photocatalytic activity, are able to generate charge carriers and induce the formation of various reactive oxygen species (ROS) in the presence of O and HO. This special feature makes TiO an important and promising material in several industrial applications. Under appropriate antioxidant balancing, the presence of ROS is crucial in plant growth and development, therefore, the regulated ROS production through the photocatalytic activity of TiO NCs may be also exploited in the agricultural sector.

Ultraviolet-B acclimation is supported by functionally heterogeneous phenolic peroxidases.

Tobacco plants were grown in plant chambers for four weeks, then exposed to one of the following treatments for 4 days: (1) daily supplementary UV-B radiation corresponding to 6.9 kJ m d biologically effective dose (UV-B), (2) daily irrigation with 0.1 mM hydrogen peroxide, or (3) a parallel application of the two treatments (UV-B + HO).

Ultraviolet-B radiation exposure lowers the antioxidant capacity in the Arabidopsis thaliana pdx1.3-1 mutant and leads to glucosinolate biosynthesis alteration in both wild type and mutant.

Pyridoxine (vitamin B6) and its vitamers are used by living organisms both as enzymatic cofactors and as antioxidants. We used Arabidopsis pyridoxine biosynthesis mutant pdx1.3-1 to study the involvement of the PLP-synthase main polypeptide PDX1 in plant responses to ultraviolet radiation of two different qualities, one containing primarily UV-A (315-400 nm) and the other containing both UV-A and UV-B (280-315 nm).

Multiple roles for Vitamin B in plant acclimation to UV-B.

Direct and indirect roles of vitamin B in leaf acclimation to supplementary UV-B radiation are shown in vitamin B deficient Arabidopsis thaliana mutant rsr4-1 and C24 wild type. Responses to 4 days of 3.9 kJ m d biologically effective UV-B dose were compared in terms of leaf photochemistry, vitamer content, and antioxidant enzyme activities; complemented with a comprehensive study of vitamer ROS scavenging capacities.

Selective responses of class III plant peroxidase isoforms to environmentally relevant UV-B doses.

Efficient hydrogen peroxide detoxification is an essential aspect of plant defence against a large variety of stressors. Among others, class III peroxidase (POD, EC 1.11.

Elevated ROS-scavenging enzymes contribute to acclimation to UV-B exposure in transplastomic tobacco plants, reducing the role of plastid peroxidases.

Leaf peroxidases play a key role in the successful acclimation of plants to low UV-B doses. The aim of the present study was to examine whether selective enhancement of alternative chloroplast antioxidant pathways achieved by chloroplast transformation affected the need for peroxidase defense. Transplastomic tobacco lines expressing glutathione reductase in combination with either dehydroascorbate reductase or glutathione-S-transferase in their plastids exhibited better tolerance to supplemental UV-B than wild type plants.

Light piping driven photosynthesis in the soil: Low-light adapted active photosynthetic apparatus in the under-soil hypocotyl segments of bean (Phaseolus vulgaris).

Photosynthetic activity was identified in the under-soil hypocotyl part of 14-day-old soil-grown bean plants (Phaseolus vulgaris L. cv. Magnum) cultivated in pots under natural light-dark cycles.

UV-B effects on leaves-Oxidative stress and acclimation in controlled environments.

As the steady decline in the Earth's stratospheric ozone layer and parallel increase in solar ultraviolet-B (UV-B: 280-315nm) has come to an end, the focus of plant UV research has been shifted from regarding UV-B as threatening plant life to recognizing it as a regulatory factor. While UV-B photoreceptor mediated signaling is increasingly understood, the role of UV-B inducible reactive oxygen species is still to be explored. Earlier experiments with high UV-B irradiation doses and isolated thylakoid membranes demonstrated the potential of UV-B to trigger oxidative stress.

Antioxidant defence in UV-irradiated tobacco leaves is centred on hydrogen-peroxide neutralization.

Greenhouse grown tobacco (Nicotiana tabacum L. cv. Petit Havana) plants were exposed to supplemental UV centred at 318 nm and corresponding to 13.

Hydrogen peroxide contributes to the ultraviolet-B (280-315 nm) induced oxidative stress of plant leaves through multiple pathways.

Solar UV-B (280-315 nm) radiation is a developmental signal in plants but may also cause oxidative stress when combined with other environmental factors. Using computer modeling and in solution experiments we show that UV-B is capable of photosensitizing hydroxyl radical production from hydrogen peroxide. We present evidence that the oxidative effect of UV-B in leaves is at least twofold: (i) it increases cellular hydrogen peroxide concentrations, to a larger extent in pyridoxine antioxidant mutant pdx1.