Chronic ozone exposure preferentially modifies root rather than foliar metabolism of date palm (Phoenix dactylifera) saplings.

In their natural environment, date palms are exposed to chronic atmospheric ozone (O3) concentrations from local and remote sources. In order to elucidate the consequences of this exposure, date palm saplings were treated with ambient, 1.5 and 2.0 times ambient O3 for three months in a free-air controlled exposure facility. Chronic O3 exposure reduced carbohydrate contents in leaves and roots, but this effect was much stronger in roots. Still, sucrose contents of both organs were maintained at elevated O3, though at different steady states. Reduced availability of carbohydrate for the Tricarboxylic acid cycle (TCA cycle) may be responsible for the observed reduced foliar contents of several amino acids, whereas malic acid accumulation in the roots indicates a reduced use of TCA cycle intermediates. Carbohydrate deficiency in roots, but not in leaves caused oxidative stress upon chronic O3 exposure, as indicated by enhanced malonedialdehyde, H2O2 and oxidized glutathione contents despite elevated glutathione reductase activity. Reduced levels of phenolics and flavonoids in the roots resulted from decreased production and, therefore, do not indicate oxidative stress compensation by secondary compounds. These results show that roots of date palms are highly susceptible to chronic O3 exposure as a consequence of carbohydrate deficiency.

Genetic analysis reveals population structuring and a bottleneck in the black-faced lion tamarin (Leontopithecus caissara).

The ability of a population to evolve in a changing environment may be compromised by human-imposed barriers to gene flow. We investigated the population structure and the possible occurrence of a genetic bottleneck in two isolated populations of the black-faced lion tamarin (Leontopithecus caissara), a species with very reduced numbers (less than 400) in a very restricted range in the Atlantic Forest of southeast Brazil. We determined the genotypes of 52 individuals across 9 microsatellite loci. We found genetic divergence between the populations, each exhibiting low genetic diversity. Analysis revealed broad- and fine-scale population structuring. Both populations have evidently experienced population reduction and a genetic bottleneck without presenting any apparent detrimental effect. Anyway, measures should be taken to effectively protect the forests where L. caissara occurs in order to allow its populations to increase and counteract the eventual effects of genetic impoverishment.

Validation of air pollution biomonitoring networks and related data modelling: a geostatistical approach.

This paper describes a geostatistical approach for environmental data modeling based on value descriptive analysis, variographic analysis, estimation method and validation. It shows an application related to atmospheric pollutant dispersion (ozone) detected by active biomonitoring in the province of Livorno (Italy). This work proposes a two-stage approach based on: the computation of an index on an exploratory and geostatistical data analysis to assess whether a monitoring network is well distributed in space and allows us to get reliable information about the whole study area; the derivation of a continuous representation of the variable (the Cotyledonous Damage Index) from punctual measurements. The geostatistical approach proposed is useful to define in a structured way the possible problems in a monitoring network, to control the data estimation error in the points not sampled. The case study analysed underlines that the biomonitoring network outline does not have a representative sample station distribution of the study area introducing significant errors related to the territorial generalization of the derived information. The proposed approach allows us to elaborate on the obtained data to carry out the data spatialization associating an error to them and to the evaluation model.

Characterization and isolation of some genes of the shikimate pathway in sensitive and resistant Centaurea jacea plants after ozone exposure.

Centaurea jacea has been suggested as a potential bioindicator for ozone, but little is known about its intraspecific variation in sensitivity, especially at molecular level. The effects of ozone (200 ppb, 5 h) on sensitive and resistant lines of Centaurea have been investigated at the end of fumigation. Sensitive plants showed characteristic symptoms of injury in the form of diffuse discoloration stipples on leaves. A PCR-based approach was used to identify and isolate a partial-length cDNA coding for PAL and CHS genes. The northern analysis of PAL showed accumulation of transcript in both lines correlated with a typical increase of PAL activity (+41 and +91% in resistant and sensitive material, respectively, compared to controls). On the contrary, the transcripts of CHS, in resistant and sensitive plants, did not change after treatment. Total phenols were not affected by ozone, while anthocyanins were quickly utilised by resistant clone as antioxidant compounds.

Integrated biomonitoring of air quality with plants and lichens: a case study on ambient ozone from central Italy.

A biennial integrated survey, based on the use of vascular plants for the bioindication of the effects of tropospheric ozone together with the use of automatic analysers of ozone, as well as the mapping of lichen biodiversity was performed in the area of Castelfiorentino (Tuscany, central Italy). Photochemically produced ozone proved to be a fundamental presence during the warm season, with maximum hourly means reaching 114 ppb, exceeding the information threshold as fixed by EU: the use of supersensitive tobacco Bel-W3 confirmed the opportunity of carrying out detailed cost-effective monitoring surveys. The potential for didactical and educational implications of this methodology are appealing. Critical levels set up for the protection of vegetation have exceeded considerably. The comparison of biomass productivity in sensitive and resistant individuals (NC-S and NC-R white clover clones, in the framework of an European network) provided evidence that ambient ozone levels are associated with relevant reduction (up to 30%) in the performance of sensitive material; effects on flowering were also pronounced. The economic assessment of such an impact deserves attention. Mapping of epiphytic lichen biodiversity--which has been used to monitor air quality worldwide--was not related to ozone geographical distribution as depicted by tobacco response.

Measuring, modelling and testing ozone exposure, flux and effects on vegetation in southern European conditions--what does not work? A review from Italy.

Ozone (O3) exposure at Italian background sites exceeds UN/ECE concentration-based critical levels (CLe(c)), if expressed in terms of AOT40. Yet the occurrence of adverse effects of O3 on forests and crops is controversial. Possible reasons include (i) ability of response indicators to provide an unbiased estimate of O3 effects, (ii) setting of current CLe(c) in terms of cut-off value and accumulation level, (iii) response functions adopted to infer a critical level, (iv) environmental limitation to O3 uptake and (v) inherent characteristics of Mediterranean vegetation. In particular, the two latter points suggest that critical levels based on accumulated stomatal flux (CLe(f)) can be a better predictor of O3 risk than CLe(c). While this concept is largely acknowledged, a number of factors may limit its applicability for routine monitoring. This paper reviews levels, uptake and vegetation response to O3 in Italy over recent years to discuss value, uncertainty and feasibility of different approaches to risk assessment.

Biological monitoring of ozone: the twenty-year Italian experience.

Tropospheric ozone is a growing environmental menace in Italy and in the whole Mediterranean basin. The importance of active biomonitoring of this pollutant with hypersensitive Bel-W3 tobacco plants is stressed, and several examples of field studies carried out in Italy with this technique are presented. Current limitations are discussed, with special emphasis on data quality assessment and the opportunity of adopting easy-to-use kits based on tobacco germlings instead of adult plants. A standardization of methodologies (from cultivation to scoring and data elaboration), also at an international level, is strongly felt to be needed, in order to get official acknowledgement of biomonitoring procedures. Potential educational implications, with the active involvement of students and environmentalists, are shown. Other biological indicators are used, namely sensitive and resistant white clover (Trifolium repens) clones (as descriptors of biomass reduction in crops species) and Centaurea jacea (brown knapweed) as a model species to evaluate the relationship between ozone exposure and effects on the performance and injury symptoms of native plants which are largely used in the framework of European programmes.

Lichen distribution and bioindicator tobacco plants give discordant response: a case study from Italy.

Epiphytic lichen biodiversity (LB) distribution was evaluated in a 1000 km2 area in Tuscany (Central Italy). In the same area, a survey was performed to monitor tropospheric ozone (O3) phytotoxic effects using tobacco plants (Nicotiana tabacum) cv. Bel-W3 (O3 supersensitive) and cv. Bel-B (O3 resistant) as bioindicators. The LB proved to be negatively correlated with ambient levels of nitrogen oxides, particulate and carbon monoxide, but not with benzene. LB spatial distribution followed a peculiar trend, with highest values in areas with low population density. Data from an O3 analyser set in evidence a typical circadian profile, confirming the photochemical nature of this pollutant. Quite high nocturnal values along the coast were related to the presence of surrounding mountains which constrained the back-and-forth flow of the air in sea breezes. Long- and short-term phytotoxicity critical levels for O3 were systematically trespassed. Bel-W3 tobacco was always affected in every site involved in the study; average O3 injury distribution was greater in rural areas; tobacco response was positively correlated to several O3 descriptors with second-order functions. Correlation analysis failed to demonstrate any association between lichen and tobacco data, due to the fact that LB values were higher in inland zones, far from the main urban and industrial areas, where instead damage to tobacco plants was generally lower. It is concluded that the lichen biodiversity is not suitable for monitoring O3 levels, at least in the study area.

Monitoring and biomonitoring of surface ozone in Florence, Italy.

An ambient air study was conducted in the city of Florence, Italy, in the summer 1996. Tropospheric ozone was continuously monitored with automatic analyzers in three stations, two located in the urban area and one in the hilly surroundings (Settignano). A biomonitoring campaign based on the tobacco cv. Bel-W3 plants was performed in the same area. The highest values were constantly recorded in the Settignano station. The highest 1-hour mean recorded was 197 nl/l; the accumulated exposure over a threshold of 40 nl/l (AOT40) was well above the critical levels standards for protection of the vegetation. A consistent temporal variation was observed and July proved to be the month with the highest ozone levels. Cumulative frequency distribution of ozone maximum daily concentrations exhibited a good fitting to log-normality. No 'week-end' effect was observed. Biomonitoring data were in good agreement with chemico-physical ones.

Effect of chronic ozone fumigation on the photosynthetic process of poplar clones showing different sensitivity.

Rooted cuttings from two poplar clones (Populus x euramericana, I-214, and Populus deltoides x maximowiczii, Eridano) were exposed for 15 days to diurnal square-wave treatment with ozone (60 nL L-1 for 5 h day-1). Completely fully expanded leaves exposed to ozone showed a reduction in net CO2 assimilation rate as compared to the control leaves during whole exposure period in both the clones. The reduction was related to a strong stomatal closure in clone I-214, but also to an altered mesophyll activity ascribed to limitation of the dark reactions of photosynthetic process. The results obtained in leaves of I-214 subjected to long-term fumigation seem to support the view that the decrease in quantum yield of electron transport may be a mechanism to down-regulate photosynthetic electron transport so that production of ATP and NADPH would be in equilibrium with the decreased demand in the Calvin cycle. In Eridano the CO2 assimilation was reduced because of the exposure and any alteration in stomatal conductance was observed. Thus, chlorophyll fluorescence parameters showed that an inhibition of photosystem II had occurred (reduction in Fv/Fm ratio), while no alterations in quenching parameters were observed upon illumination. The results seem to indicate that an alternative sink for reducing equivalent, other than carbon metabolism is present.

First Report of Erysiphe cichoracearum Infecting Hedera canariensis var. azorica in Italy.

A powdery mildew disease of variegated ivy (Hedera canariensis L. var. azorica) was observed on the Tyrrhenian coast in Tuscany (Italy) in spring 1998. Symptoms began as small, nearly circular reddish spots that later enlarged and coalesced. The hyaline mycelium produced abundant, ellipsoid conidia in long chains that ranged from 20 to 40 µm in length and from 12 to 25 µm in width. Cleistothecia were globose (100 to 120 µm diameter), dark brown (when mature) with a basal ring of mycelioid appendages, and contained several (up to 20) ovate asci, each generally containing two ascospores. Ascospores were hyaline, one-celled, ellipsoid (20 to 35 µm in length and 10 to 20 µm in width). The morphological characteristics of this fungus were those given for Erysiphe cichoracearum DC. Infection also was found on English ivy (Hedera helix L.). It is reported that this species is, occasionally, subject to powdery mildew caused by E. cichoracearum (1). Conidia from infected leaves were shaken onto leaves of melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai), lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.) and variegated and English ivy. After 7 days, the disease was observed on cucumber, melon, watermelon, tobacco, and variegated ivy. Examination confirmed that test plants were infected with E. cichoracearum. This is the first report of E. cichoracearum on variegated ivy in Italy. Reference: (1) P. P. Pirone. 1970. Diseases and Pests of Ornamental Plants. The Ronald Press, New York.

An analysis of the distribution of surface ozone in Tuscany (central Italy) with the use of a new miniaturized bioassay with ozone-sensitive tobacco seedlings.

An innovative miniaturized kit based on the use of 2-week-old ozone-supersensitive tobacco germlings (Nicotiana tabacum L. cv. Bel-W3) raised in tissue culture plates was utilized, in conjunction with four calibrated automatic analyzers, to monitor the distribution of phytotoxic ground level ozone in Tuscany during the summer of 1993 at 27 sites differing in nature. Germlings of ozone-resistant Bel-B tobacco were also included in the protocol. The intensity of visible injury on the cotyledons of Bel-W3 was linearly correlated with several ozone statistical descriptors. The occurrence of phytotoxic levels of photochemical ozone was detected in all the monitoring sites, which included rural and remote areas, whose local sources of pollution were negligible. The suitability of the new methodology for low-cost, space-saving, user-friendly monitoring of ozone on a large geographical scale is discussed.