Assessment of seasonal variations in particulate matter accumulation and elemental composition in urban tree species.

Outdoor air pollution in urban areas, especially particulate matter (PM), is harmful to human health. Urban trees and shrubs provide crucial ecosystem services such as air pollution mitigation by acting as natural filters. However, urban greenery comprises a particular biodiversity, and different plant species vary in their capacity to accumulate PM. Twenty-two plant species were analyzed and selected according to their leaf traits, the different fractions of PM accumulated on the leaves (large - PML, coarse - PMC, and fine - PMF) and their chemical composition. The study was conducted in four city zones: urban traffic (UT), urban background (UB), industrial (IND), and rural (RUR), comparing winter (W) and summer (S) seasons. The average PM levels in the air and accumulated on the leaves were higher in W than in S season. During both seasons, the highest PM accumulated on the leaves was recorded at the UT zone. Nine species were selected as the most suitable for accumulating PML, seven as the most efficient for accumulating PMC, and six for accumulating PMF. The leaf area and leaf roundness were correlated negatively with PM accumulation. The evergreen species L. nobilis was indicated as suitable for dealing with air pollution based on PM10 and PM2.5 values recorded in the air. Regarding the PM element and metal composition, L. nobilis, Photinia x fraseri, Olea europaea, Quercus ilex and Nerium oleander were selected as species with notable elements and metal accumulation. In summary, the study identified species with higher PM accumulation capacity and assessed the seasonal PM accumulation patterns in different city zones, providing insights into the species interactions with PM and their potential for monitoring and coping with air pollution.

Detection of morphological and eco-physiological traits of ornamental woody species to assess their potential Net O3 uptake.

Urban greening can improve cities' air quality by filtering the main gaseous pollutants such as tropospheric ozone (O3). However, the pollutant removal capacity offered by woody species strongly depends on eco-physiological and morphological traits. Woody species with higher stomatal conductance (gs) can remove more gases from the atmosphere, but other species can worsen air quality due to high O3 forming potential (OFP), based on their emitting rates of biogenic volatile organic compounds (bVOCs) and Leaf Mass per Area (LMA). Presently, there is a lack of data on eco-physiological (gs, bVOCs emissions) and foliar traits (LMA) for several ornamental species used in urban greening programs, which does not allow assessment of their O3 removal capacity and OFP. This study aimed to (i) parameterize gs, assess bVOCs emissions and LMA of 14 ornamental woody species commonly used in Mediterranean urban greening, and (ii) model their Net O3 uptake. The gs Jarvis model was parameterized considering various environmental conditions alongside isoprene and monoterpene foliar bVOCs emission rates trapped in the field and quantified by gas chromatography-mass spectrometry. The results are helpful for urban planning and landscaping; suggesting that Catalpa bignonioides and Gleditsia triacanthos have excellent O3 removal capacity due to their high maximum gs (gmax) equal to 0.657 and 0.597 mol H2O m-2 s-1. Regarding bVOCs, high isoprene (16.75 µg gdw-1 h-1) and monoterpene (13.12 µg gdw-1 h-1) emission rates were found for Rhamnus alaternus and Cornus mas. In contrast, no bVOCs emissions were detected for Camellia sasanqua and Paulownia tomentosa. In conclusion, 11 species showed a positive Net O3 uptake, while the use of large numbers of R. alaternus, C. mas, and Chamaerops humilis for urban afforestation planning are not recommended due to their potential to induce a deterioration of outdoor air quality.

An assessment of ozone risk for date palm suggests that phytotoxic ozone dose nonlinearly affects carbon gain.

Tropospheric ozone (O3) is a significant phytotoxic air pollutant that has a negative impact on plant carbon gain. Although date palm (Phoenix dactylifera L.) is a globally important crop in arid or semi-arid regions, so far O3 risk assessment for this species has not been reported. This study estimated leaf- and plant-level photosynthetic CO2 uptake for understanding how elevated levels of O3 affects date palm biomass growth. Ozone risks to date palm plants were assessed based on exposure- (AOT40) or flux-based indices (Phytotoxic Ozone Dose, PODy, where y is a threshold of uptake). For this purpose, plants were exposed to three levels of O3 [ambient air, AA (45 ppb as daily average); 1.5 × AA; 2.0 × AA] for 92 days in an O3 Free-Air Controlled Exposure facility. According to the model simulations, the negative effects of O3 on plant-level net photosynthetic CO2 uptake were attributed to reduced gross photosynthetic carbon gain and increased respiratory carbon loss. Season-long O3 exposure and elevated temperatures promoted the negative O3 effect because of a further increase of respiratory carbon loss, which was caused by increased leaf temperature due to stomatal closure. POD1 nonlinearly affected the photosynthetic CO2 uptake, which was closely related to the variation of dry mass increment during the experiment. Although the dose-response relationship suggested that a low O3 dose (POD1 < 5.2 mmol m-2) may even positively affect photosynthetic CO2 uptake in date palms, stomatal O3 uptake at the current ambient O3 levels has potentially a negative impact on date palm growth. The results indicate 5.8 mmol m-2 POD1 or 21.1 ppm h AOT40 as critical levels corresponding to a 4% reduction of net CO2 uptake for date palm, suggesting that this species can be identified as a species moderately sensitive to O3.

A three-year free-air experimental assessment of ozone risk on the perennial Vitis vinifera crop species.

Tropospheric ozone (O3) is an oxidative air pollutant that promotes damage to several crops, including grapevine, which is considered moderately resistant to O3 stress. To study the O3 effect on this perennial crop species under realistic environmental conditions, a three-year experiment was performed using an innovative O3-FACE facility located in the Mediterranean climate region, where the target species, Vitis vinifera cv. "Cabernet sauvignon", was exposed to three O3 levels: ambient (AA), 1.5 × ambient (×1.5), and 2 × ambient (×2.0). A stomatal conductance model parameterization was conducted, and O3-exposure (AOT40) and flux-based indices (PODy) were estimated. An assessment of O3-induced visible foliar injury (O3_VFI) was conducted by estimating VFI_Incidence (percentage of symptomatic leaves per branch) and VFI_Severity (average percentage of O3_VFI surface in symptomatic leaves). Biomass parameters were used to assess the cumulative O3 effect and calculate the most appropriate critical levels (CL) for a 5% yield loss and for the induction of 5, 10, and 15% of O3_VFI. We confirmed that the O3 effect on this grapevine variety VFI was cumulative and that POD0 values accumulated over the two or three years preceding the assessment were better related to the response variables than single-year values, with the response increasing with increasing O3 level. The estimated CL for 5% yield loss based on the O3-exposure index was 25 ppm h AOT40 and 21 or 23 ppm h for a 10% of VFI_Incidence or VFI_Severity, respectively. The suggested flux-based index value for 5% yield loss was 5.2 POD3 mmol m-2, and for 10% of VFI_Incidence or VFI_Severity, the values were 7.7 or 8.6 POD3 mmol m-2, respectively. The results presented in this study demonstrate that O3 risk assessment for this grapevine varietyproduces consistent and comparable results when using either yield or O3_VFI as response parameter.

The magpie and the grapes: increasing ozone exposure impacts fruit consumption by a common corvid in a suburban environment.

BACKGROUND: The Eurasian magpie Pica pica is a resident bird species able to colonize farmlands and anthropized environments. This corvid shows a wide trophic spectrum by including fruits, invertebrates, small vertebrates and carcasses in its diet. A camera-trap experiment was carried out to test the effect of different ozone (O3 ) concentrations on potted Vitis vinifera plants, which resulted in different grape consumption rates by suburban birds. The test was performed at an Ozone-Free Air Controlled Exposure (FACE) facility, consisting of nine plots with three ozone (O3 ) levels: AA (ambient O3 concentration); and two elevated O3 levels, 1.5× AA (ambient air with a 50% increase in O3 concentration) and 2.0× AA (ambient air with a 100% increase in O3 concentration). Camera-traps were located in front of each treatment area and kept active for 24 h day-1 and for 5 days at a time over a period of 3 months to monitor grape consumption by birds. RESULTS: We collected a total of 38 videos. Eurasian magpies were the only grape consumers, with a total of 6.7 ± 3.3 passages per hour (mean ± SD) and no differences across the different O3 treatments. Grapes in the AA treatment were consumed significantly more quickly than those in the 1.5× AA treatment, which in turn, were consumed faster than those in the 2.0× AA treatment. At 3 days from the start of treatment, 94%, 53% and 22% berries from the AA, 1.5× AA and 2.0× AA treatments had been eaten, respectively. When the O3 was turned off, berries were consumed at the same rate among treatments. CONCLUSION: Increasing O3 concentrations limited grape consumption by magpies probably because O3 acted as a deterrent for magpies, although the lower sugar content recorded in the 2.0× AA berries did not affect the consumption when O3 was turned off. Our results provided valuable insights to mitigate human-wildlife conflicts in suburban environments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Unveiling resilience mechanisms of Quercus ilex seedlings to severe water stress: Changes in non-structural carbohydrates, xylem hydraulic functionality and wood anatomy.

Over the last few decades, extensive dieback and mortality episodes of Quercus ilex L. have been documented after severe drought events in many Mediterranean forests. However, the underlying physiological, anatomical, and biochemical mechanisms remain poorly understood. We investigated the physiological and biochemical processes linked to embolism formation and non-structural carbohydrates (NSCs) dynamics in Q. ilex seedlings exposed to severe water stress and rewatering. Measurements of leaf gas exchange, water relations, non-structural carbohydrates, drought-related gene expression, and anatomical changes in wood parenchyma were assessed. Under water stress, the midday stem water potential dropped below - 4.5 MPa corresponding to a ~ 50 % loss of hydraulic conductivity. A 70 % reduction in stomatal conductance led to a strong depletion of wood NSCs. Starch consumption, resulting from the upregulation of the ß-amylase gene BAM3, together with the downregulation of glucose (GPT1) and sucrose (SUC27) transport genes, suggests glucose utilization to sustain cellular metabolism in the wood parenchyma. After rewatering, the presence of residual xylem embolism led to an incomplete recovery of leaf gas exchanges. However, the partial restoration of photosynthesis allowed the accumulation of new starch reserves in the wood parenchyma and the production of new narrower vessels. In addition, changes in the cell wall composition of the wood parenchyma fibers were observed. Our findings indicate that thirty days of rewatering were sufficient to restore the NSCs reserves and growth rates of Q. ilex seedlings and that the carryover effects of water stress were primarily caused by hydraulic dysfunction.

Ozone Impact on Emission of Biogenic Volatile Organic Compounds in Three Tropical Tree Species From the Atlantic Forest Remnants in Southeast Brazil.

Plants emit a broad number of Biogenic Volatile Organic Compounds (BVOCs) that can impact urban ozone (O3) production. Conversely, the O3 is a phytotoxic pollutant that causes unknown alterations in BVOC emissions from native plants. In this sense, here, we characterized the constitutive and O3-induced BVOCs for two (2dO3) and four (4dO3) days of exposure (O3 dose 80 ppb) and evaluated the O3 response by histochemical techniques to detect programmed cell death (PCD) and hydrogen peroxide (H2O2) in three Brazilian native species. Croton floribundus Spreng, Astronium graveolens Jacq, and Piptadenia gonoacantha (Mart.) JF Macbr, from different groups of ecological succession (acquisitive and conservative), different carbon-saving defense strategies, and specific BVOC emissions. The three species emitted a very diverse BVOC composition: monoterpenes (MON), sesquiterpenes (SEQ), green leaf volatiles (GLV), and other compounds (OTC). C. floribundus is more acquisitive than A. graveolens. Their most representative BVOCs were methyl salicylate-MeSA (OTC), (Z) 3-hexenal, and (E)-2-hexenal (GLV), γ-elemene and (-)-ß-bourbonene (SEQ) ß-phellandrene and D-limonene (MON), while in A. graveolens were nonanal and decanal (OTC), and α-pinene (MON). Piptadenia gonoachanta is more conservative, and the BVOC blend was limited to MeSA (OTC), (E)-2-hexenal (GLV), and ß-Phellandrene (MON). The O3 affected BVOCs and histochemical traits of the three species in different ways. Croton floribundus was the most O3 tolerant species and considered as an SEQ emitter. It efficiently reacted to O3 stress after 2dO3, verified by a high alteration of BVOC emission, the emergence of the compounds such as α-Ionone and trans-ß-Ionone, and the absence of H2O2 detection. On the contrary, A. graveolens, a MON-emitter, was affected by 2dO3 and 4dO3, showing increasing emissions of α-pinene and ß-myrcene, (MON), γ-muurolene and ß-cadinene (SEQ) and H2O2 accumulation. Piptadenia gonoachanta was the most sensitive and did not respond to BVOCs emission, but PCD and H2O2 were highly evidenced. Our results indicate that the BVOC blend emission, combined with histochemical observations, is a powerful tool to confirm the species' tolerance to O3. Furthermore, our findings suggest that BVOC emission is a trade-off associated with different resource strategies of species indicated by the changes in the quality and quantity of BVOC emission for each species.

Visible Foliar Injury and Ecophysiological Responses to Ozone and Drought in Oak Seedlings.

To verify the responses of visible foliar injury (VFI), we exposed seedlings of three oak species for 4.5 months in an open air facility, using differing ozone (O3) and drought treatments: O3 (three levels from ambient to ×1.4 ambient), and drought (three levels of irrigation from 40% to 100% field capacity). We related the accumulated phytotoxic O3 dose (POD1) and cumulative drought index (CDI) to the O3 and drought VFI and assessed growth increment (height, diameter, leaf number), biomass (of all organs), and physiological parameters: net photosynthesis per plant (Pn), photosynthetic nitrogen (PNUE) and phosphorus use efficiency (PPUE)). The results indicated that an increase in POD1 promoted O3 VFI in Quercus robur and Quercus pubescens, while Quercus ilex was asymptomatic. The POD1-based critical level at the onset of O3 VFI was lower for Q. robur than for Q. pubescens (12.2 vs. 15.6 mmol m-2 POD1). Interestingly, drought reduced O3 VFI in Q. robur but increased it in Q. pubescens. Both O3 and drought were detrimental to the plant biomass. However, Q. robur and Q. pubescens invested more in shoots than in roots, while Q. ilex invested more in roots, which might be related to a hormetic mechanism. Pn, PNUE and PPUE decreased in all species under drought, and only in the sensitive Q. robur (PPUE) and Q. pubescens (PNUE) under O3. This study confirms that POD1 is a good indicator to explain the development of O3 VFI and helps a differential diagnosis of co-occurring drought and O3 VFI in oak forests.

Experimental assessment of ozone risk on ecotypes of the tropical tree Moringa oleifera.

Ozone (O3) is an oxidative air pollutant that affects plant growth. Moringa oleifera is a tree species distributed in the tropical and subtropical regions. This species presents high morphological plasticity, which increases its ability to tolerate stressful conditions, but with no O3 risk assessment calculated so far. The present study assessed the O3 risk to different M. oleifera ecotypes using exposure-based index (AOT40) or flux-based index (PODy - where y is a threshold of O3 uptake). PODy considers the O3 uptake through the stomata and the consequence of environmental climate conditions on stomatal conductance (gsto); thus, it is efficient in assessing O3 risk. Five M. oleifera ecotypes were subjected to ambient (Amb.); middle (Mid. X1.5), and High (x2.0) O3 concentrations for 77 days in a free-air controlled exposure facility (FACE). Leaf biomass (LB) was evaluated, and the biomass loss was projected assuming a clean atmosphere (10 ppb as 24 h O3 average). The gsto parameterization was calculated using the Jarvis-type multiplicative algorithm considering several climate factors, i.e., light intensity, air temperature, air vapor pressure deficit, and AOT40. Ozone exposure harmed the LB of all ecotypes. The high gsto (~559 mmol H2O m-2 s-1) can be considered the reason for the species' O3 sensitivity. M. oleifera is adapted to hot climate conditions, and gsto was restricted with air temperature (Tmin) below ~ 9 °C. As expected, the PODy index performed better than the AOT40 for estimating the O3 effect on biomass losses. We recommend a y threshold of 4 nmol m-2 s-1 to incorporate O3 effects on M. oleifera LB. To not exceed a 4% reduction of LB for any M. oleifera genotype, we recommend the critical levels of 1.1 mmol m-2 POD4.

Foliage visible injury in the tropical tree species, Astronium graveolens is strictly related to phytotoxic ozone dose (PODy).

The present study evaluates the development of visible injury related to phytotoxic ozone dose (PODy) in native tropical species Astronium graveolens Jacq. (Anacardiaceae) and validates the symptoms using structural markers attributed to oxidative burst and hypersensitive responses. Increasing POD0 was associated with increasing O3 visible injury using different metrics as the incidence (INC = number of injured plants/total number of plants × 100), severity (SF = number of injured leaves/total number of leaves on injured plant × 100), and severity leaflet (SFL = number of injured leaflets/total number leaflets injured plant × 100). The effective dose (ED), which represents the POD0 dose responsible for inducing 20 (ED20), 50 (ED50), or 80% (ED80) of visible injury, were used to demonstrate that for this species, the response is similar even when the plants are exposed to diverse climate environments. Further investigation of the INC and SF index may help in long-term forest monitoring sites dedicated to O3 assessment in forests, while the SFL index seems to be an excellent indicator to be used in the short term to investigate the effects of O3.

Phenotypic plasticity of two M. oleifera ecotypes from different climatic zones under water stress and re-watering.

Moringa oleifera is a fast-growing hygrophilic tree native to a humid sub-tropical region of India, now widely planted in many regions of the Southern Hemisphere characterized by low soil water availability. The widespread cultivation of this plant worldwide may have led to populations with different physiological and biochemical traits. In this work, the impact of water stress on the physiology and biochemistry of two M. oleifera populations, one from Chaco Paraguayo (PY) and one from Indian Andhra Pradesh (IA) region, was studied in a screenhouse experiment where the water stress treatment was followed by re-watering. Through transcriptome sequencing, 2201 potential genic simple sequence repeats were identified and used to confirm the genetic differentiation of the two populations. Both populations of M. oleifera reduced photosynthesis, water potential, relative water content and growth under drought, compared to control well-watered plants. A complete recovery of photosynthesis after re-watering was observed in both populations, but growth parameters recovered better in PY than in IA plants. During water stress, PY plants accumulated more secondary metabolites, especially ß-carotene and phenylpropanoids, than IA plants, but IA plants invested more into xanthophylls and showed a higher de-epoxidation state of xanthophylls cycle that contributed to protect the photosynthetic apparatus. M. oleifera demonstrated a high genetic variability and phenotypic plasticity, which are key factors for adaptation to dry environments. A higher plasticity (e.g. in PY plants adapted to wet environments) will be a useful trait to endure recurrent but brief water stress episodes, whereas long-term investment of resources into secondary metabolism (e.g. in IA plants adapted to drier environments) will be a successful strategy to cope with prolonged periods of drought. This makes M. oleifera an important resource for agro-forestry in a climate change scenario.

Ozone affects leaf physiology and causes injury to foliage of native tree species from the tropical Atlantic Forest of southern Brazil.

In southern Brazil, the recent increase in tropospheric ozone (O3) concentrations poses an additional threat to the biodiverse but endangered and fragmented remnants of the Atlantic Forest. Given the mostly unknown sensitivity of tropical species to oxidative stress, the principal objective of this study was to determine whether the current O3 levels in the Metropolitan Region of Campinas (MRC), downwind of São Paulo, affect the native vegetation of forest remnants. Foliar responses to O3 of three tree species typical of the MRC forests were investigated using indoor chamber exposure experiments under controlled conditions and a field survey. Exposure to 70ppb O3 reduced assimilation and leaf conductance but increased respiration in Astronium graveolens while gas exchange in Croton floribundus was little affected. Both A. graveolens and Piptadenia gonoacantha developed characteristic O3-induced injury in the foliage, similar to visible symptoms observed in >30% of trees assessed in the MRC, while C. floribundus remained asymptomatic. The underlying structural symptoms in both O3-exposed and field samples were indicative of oxidative burst, hypersensitive responses, accelerated cell senescence and, primarily in field samples, interaction with photo-oxidative stress. The markers of O3 stress were thus mostly similar to those observed in other regions of the world. Further research is needed, to estimate the proportion of sensitive forest species, the O3 impact on tree growth and stand stability and to detect O3 hot spots where woody species in the Atlantic Forest are mostly affected.

Tillandsia usneoides: A successful alternative for biomonitoring changes in air quality due to a new highway in São Paulo, Brazil.

Tillandsia usneoides is an aerial epiphytic bromeliad that absorbs water and nutrients directly from the atmosphere by scales covering its surface. We expanded the use of this species as a broader biomonitor based on chemical and structural markers to detect changes in air quality. The usefulness of such comprehensive approach was tested during the construction and opening of a highway (SP-21) in São Paulo State, Brazil. The biomonitoring study was performed from 2009 to 2012, thus comprising the period during construction and after the highway inauguration. Metal accumulation and structural alterations were assessed, in addition to microscopy analyses to understand the metal chelation in plant tissues and to assess the causes of alterations in the number and shape of scale cells. Altogether, our analyses support the use of this species as a wide biomonitor of air quality in urbanized areas.

Tillandsia usneoides: a successful alternative for biomonitoring changes in air quality due to a new highway in São Paulo, Brazil.

Tillandsia usneoides is an aerial epiphytic bromeliad that absorbs water and nutrients directly from the atmosphere by scales covering its surface. We expanded the use of this species as a broader biomonitor based on chemical and structural markers to detect changes in air quality. The usefulness of such comprehensive approach was tested during the construction and opening of a highway (SP-21) in São Paulo State, Brazil. The biomonitoring study was performed from 2009 to 2012, thus comprising the period during construction and after the highway inauguration. Metal accumulation and structural alterations were assessed, in addition to microscopy analyses to understand the metal chelation in plant tissues and to assess the causes of alterations in the number and shape of scale cells. Altogether, our analyses support the use of this species as a wide biomonitor of air quality in urbanized areas.

Comparative study of Passiflora taxa leaves: I. A morpho-anatomic profile

AbstractDetermining the authenticity and quality of plant raw materials used in the formulation of herbal medicines, teas and cosmetics is essential to ensure their safety and efficacy for clinical use. Some Passiflora species are officially recognized in the pharmaceutical compendia of various countries and have therapeutic uses, particularly as sedatives and anxiolytics. However, the large number of Passiflora species, coupled with the fact that most species are popularly known as passion fruit, increases the misidentification problem. The purpose of this study is to make a pharmacognostic comparison between various Passiflora species to establish a morpho-anatomical profile that could contribute to the quality control of herbal drug products that contain passion fruit. This was conducted by collecting samples of leaves from twelve Passiflora taxa (ten species and two forms of P. edulis): P. actinia, P. alata, P. amethystina, P. capsularis, P. cincinnata, P. edulisf. flavicarpa, P. edulis f. edulis, P. incarnata, P. morifolia, P. urnifolia, P. coccinea and P. setacea, from different locations and their morpho-anatomical features were analyzed using optical microscopy and scanning electron microscopy. Microscopic analysis allowed to indicate a set of characters that can help to differentiate species. These include midrib and petiole shape, midrib and petiole vascular pattern, medium vein shape, presence of trichomes, presence of blade epidermal papillae and sclerenchymatic cells adjoining the vascular bundles. These characters could be used to assist in the determination of herbal drug quality and authenticity derived from a species of Passiflora.

Response of Brazilian native trees to acute ozone dose.

Ozone (O3) is a toxic secondary pollutant able to cause an intense oxidative stress that induces visual symptoms on sensitive plant species. Controlled fumigation experiment was conducted with the aim to verify the O3 sensibility of three tropical species: Piptadenia gonoachanta (Mart.) Macbr. (Fabaceae), Astronium graveolens Jacq. (Anacardiaceae), and Croton floribundus Spreng. (Euphorbiaceae). The microscopical features involved in the oxidative stress were recognized based on specific histochemical analysis. The three species showed visual symptoms, characterized as necrosis and stippling between the veins, mostly visible on the adaxial leaf surface. All the studied species presented hypersensitive-like response (HR-like), and peroxide hydrogen accumulation (H2O2) followed by cell death and proanthocyanidin oxidation in P. gonoachanta and A. graveolens. In P. gonoachanta, a decrease in chlorophyll autofluorescence occurred on symptomatic tissues, and in A. graveolens and C. floribundus, a polyphenol compound accumulation occurred. The responses of Brazilian native species were similar to those described for sensitive species from temperate climate, and microscopical markers may be useful for the detection of ozone symptoms in future studies in the field.