Ozone uptake at night is more damaging to plants than equivalent day-time flux.

Plants exposed to equivalent ozone fluxes administered during day-time versus night-time exhibited greater losses in biomass at night and this finding is attributed to night-time depletion of cell wall-localised ascorbate. The present study employed Lactuca sativa and its closest wild relative, L. serriola, to explore the relative sensitivity of plants to ozone-induced oxidative stress during day-time versus night-time.

A method for analysing small samples of floral pollen for free and protein-bound amino acids.

Pollen provides floral visitors with essential nutrients including proteins, lipids, vitamins and minerals. As an important nutrient resource for pollinators, including honeybees and bumblebees, pollen quality is of growing interest in assessing available nutrition to foraging bees. To date, quantifying the protein-bound amino acids in pollen has been difficult and methods rely on large amounts of pollen, typically more than 1 g.

A CAM- and starch-deficient mutant of the facultative CAM species Mesembryanthemum crystallinum reconciles sink demands by repartitioning carbon during acclimation to salinity.

In the halophytic species Mesembryanthemum crystallinum, the induction of crassulacean acid metabolism (CAM) by salinity requires a substantial investment of resources in storage carbohydrates to provide substrate for nocturnal CO(2) uptake. Acclimation to salinity also requires the synthesis and accumulation of cyclitols as compatible solutes, maintenance of root respiration, and nitrate assimilation. This study assessed the hierarchy and coordination of sinks for carbohydrate in leaves and roots during acclimation to salinity in M.

Enhanced nitrogen deposition exacerbates the negative effect of increasing background ozone in Dactylis glomerata, but not Ranunculus acris.

The combined impacts of simulated increased nitrogen (N) deposition (75 kg Nha(-1)yr (-1)) and increasing background ozone (O(3)) were studied using two mesotrophic grassland species (Dactylis glomerata and Ranunculus acris) in solardomes, by means of eight O(3) treatments ranging from 15.5 ppb to 92.7 ppb (24h average mean).

A new method for using 18O to trace ozone deposition.

Isotopically labelled ozone ((18)O(3)) is an ideal tool to study the deposition of O(3) to plants and soil, but no studies have made use of it due to the technical difficulties in producing isotopically enriched ozone. For (18)O(3) to be used in fumigation experiments, it has to be purified and stored safely prior to fumigations, to ensure that the label is present predominantly in the form of O(3), and to make efficient use of isotopically highly enriched oxygen. We present a simple apparatus that allows for the safe generation, purification, storage, and release of (18)O(3).

A new stable isotope approach identifies the fate of ozone in plant-soil systems.

* We show that the stable isotope (18)O can be used to trace ozone into different components of the plant-soil system at environmentally relevant concentrations. * We exposed plants and soils to (18)O-labelled ozone and used isotopic enrichment in plant dry matter, leaf water and leaf apoplast, as well as in soil dry matter and soil water, to identify sites of ozone-derived (18)O accumulation. * It was shown that isotopic accumulation rates in plants can be used to infer the location of primary ozone-reaction sites, and that those in bare soils are dependent on water content.

The use of ozone in the remediation of polycyclic aromatic hydrocarbon contaminated soil.

The potential of using ozone for the removal of phenanthrene from several different soils, both alone and in combination with biodegradation using a microbial inoculant (Pseudomonas alcaligenes PA-10), was examined. The greater the water content of the soil the less effective the ozone treatment, with air-dried soils showing the greatest removal of phenanthrene; while soils with higher levels of clay also reduced the effectiveness of the ozone treatments. However, at least a 50% reduction in phenanthrene levels was achieved in air-dried soil after an ozone treatment of 6 h at 20 ppm, with up to 85% removal of phenanthrene achieved in sandy soils.

The function of ascorbate oxidase in tobacco.

The function of the apoplastic enzyme ascorbate oxidase (AO) was investigated in tobacco (Nicotiana tabacum). The abundance of AO mRNA was up-regulated by light. Cytosolic ascorbate peroxidase (APX1) transcripts were also highest in the light.

Impacts of ozone on Plantago major: apoplastic and symplastic antioxidant status.

The aim of this work was to examine the correspondence between apoplastic/symplastic antioxidant status and previously reported plant age-related shifts in the ozone (O ) resistance of Plantago major L. Seed-grown plants were fumigated in duplicate controlled environment chambers with charcoal/Purafil?-filtered air (CFA) or CFA plus 70 nmol mol O for 7 h d over a 42 d period. Measurements of stomatal conductance and antioxidants were made after 14, 28 and 42 d fumigation, on leaves at an equivalent stage of development (youngest fully expanded leaf, measured c.

Potential effects of rising tropospheric concentrations of CO and O on green-algal lichens.

Pormelia sulcata Taylor was used as a model to examine the effects of elevated CO and/or O on green algal lichens. Thalli were exposed for 30 d in duplicate controlled-environment chambers to two atmospheric concentrations of CO ('ambient' [350μmol mol ] and 'elevated' [700μmol mol ] 24 h d ) and two O regimes ('non-polluted' air [CF, < 5 nmol mol ] and 'polluted' air [15 nmol mol overnight rising to a midday maximum of 75 nmol mol ]), in a factorial design. Elevated CO , or elevated O depressed the light saturated rate of CO , assimilation A ) measured at ambient CO , by 30% and 18%, respectively.