A cDNA of 312 bp, similar to polygalacturonase-inhibiting proteins(PGIPs), was isolated by cDNA-amplified fragment lengthpolymorphism (cDNA-AFLP) from pea roots infected with thecyst nematode Heterodera goettingiana. The deduced aminoacid sequence obtained from the complete Pspgip1 codingsequence was very similar to PGIPs described from several otherplant species, and was identical in both MG103738 and Progress9 genotypes, resistant and susceptible to H. goettingiana, respectively.Reverse transcription-polymerase chain reaction (RT-PCR)expression analysis revealed the differential regulation of thePspgip1 gene in the two genotypes in response to wounding andnematode challenge. Mechanical wounding induced Pspgip1expression in MG103738 within 8 h, but this response wasdelayed in Progress 9. In contrast, the response to nematodeinfection was more complex. The transcription of Pspgip1 wastriggered rapidly in both genotypes, but the expression levelreturned to levels observed in uninfected plants more quickly insusceptible than in resistant roots. In addition, in situ hybridizationshowed that Pspgip1 was expressed in the cortical cellsdamaged as a result of nematode invasion in both genotypes.However, it was specifically localized in the cells bordering thenematode-induced syncytia in resistant roots. This suggests arole for this gene in counteracting nematode establishmentinside the root.

The wide range of feeding types and the ability to adapt to seasonal succession make nematodes significant indicators of ecological conditions of the soil in which they occur. Soil nematophauna is highly sensitive to any environmental damage and, therefore, the analysis of soil nematode community can be a useful diagnostic tool of soil health changes caused by polluting agents, among which also pesticides. Traditional morpho-taxonomic techniques for analysis of soil nematophauna have been flanked or substituted by more innovative and quicker molecular tools. Effectiveness of morpho-taxonomic and molecular techniques was comparatively evaluated through the analysis of soil nematode community from three selected relatively undisturbed and disturbed sites in Apulia region (Italy). Nematodes for both analyses were extracted from 100g sub-samples of composite soil samples collected at each site. Specimens for morphological analysis were fixed in a 2.5% formaldehyde solution and then identified at family and genus level under an optical microscope. The maturity and trophic diversity indices were determined. Total DNA was extracted from the nematode community of each soil subsample and PCR amplification was performed by using the small subunit (18s) of the ribosomal DNA gene, as diagnostic marker. The 18s rDNA was selected because of the large number of 18s sequences in GenBank, the existence of an 18s-based phylogenetic tree and the conserved nature of this gene to ensure complete phylogenetic coverage of the phylum. Sequence analysis through BLAST allowed to classify most of them at genus level and some of them at species level. Few sequences showed no similarity with those present in the database suggesting that they are new for the scientific community. The maturityand trophic diversity indices were also calculated for genera identified at molecular level. Results confirmed that nematodes are good indicators of soil health, as showing a different level of disturbance for each of the three sampled sites. Both morpho-taxonomic and molecular tecniques showed to be effective, though morpho-taxonomic is more time-consuming and skilfulness-requiring whereas a molecular analysis is largely more expensive.

This study shows the direct effect of atmospheric particulate matter on plant growth. Tomato (Solanum lycopersicum L.) plants were grown for 18d directly on PM10 collected on quartz fiber filters. Organic and elemental carbon and polycyclic aromatic hydrocarbons (PAHs) contents were analyzed on all the tested filters. The toxicity indicators (i.e., seed germination, root elongation, shoot and/or fresh root weight, chlorophyll and carotenoids content) were quantified to study the negative and/or positive effects in the plants via root uptake. Substantial differences were found in the growth of the root apparatus with respect to that of the control plants. A 17-58% decrease of primary root elongation, a large amount of secondary roots and a decrease in shoot (32%) and root (53-70%) weights were found. Quantitative analysis of the reactive oxygen species (ROS) indicated that an oxidative burst in response to abiotic stress occurred in roots directly grown on PM10, and this detrimental effect was also confirmed by the findings on the chlorophyll content and chlorophyll-to-carotenoid ratio.

Main conclusion BTH application is effective in root-knot nematode-tomato interaction in a way that involves a delay in the formation of nematode feeding site and triggers molecular responses at several levels. The compatible interaction between root-knot nematodes and their hosts requires the nematode to overcome plant defense systems so that a sophisticated permanent feeding site (giant cells) can be produced within the host roots. It has been suggested that activators of plant defenses may provide a novel management strategy for controlling root-knot nematodes but little is known about the molecular basis by which these elicitors operate. The role of pre-treatment with Benzothiadiazole (BTH), a salicylic acid analog, in inducing resistance against Meloidogyne incognita infection was investigated in tomato roots. A decrease in galling in roots and feeding site numbers was observed following BTH treatment. Histological investigations showed a delay in formation of feeding sites in treated plants. BTH-treated galls had higher H2O2 production, lignin accumulation, and increased peroxidase activity than untreated galls. The expression of two tomato genes, Tap1 and Tap2, coding for anionic peroxidases, was examined by qRT-PCR and in situ hybridization in response to BTH. Tap1 was induced at all infection points, reaching the highest level at 15 dpi. Tap2 expression, although slightly delayed in untreated galls, increased during infection in both treated and untreated galls. The expression of Tap1 and Tap2 was observed in giant cells of untreated roots, whereas the transcripts were localized in both giant cells and in parenchyma cells surrounding the developing feeding sites in treated plants. These results show that BTH applied to tomato plants makes them more resistant to infection by nematodes, which become less effective in overcoming root defense pathway.

La tutela e la gestione del suolo richiedono grande attenzione, viste le importanti funzioni ambientali, economiche, sociali eculturali che il suolo stesso svolge. I nematodi del suolo possono costituire degli utili bioindicatori dello stato di salute di unsuolo, in quanto sono in grado di rispondere prontamente ai cambiamenti ambientali (stress e inquinamento) e pertantol"analisi della loro distribuzione e attività può essere usata per stabilire lo stato di conservazione di un suolo. Ilbiomonitoraggio della nematofauna può essere condotto utilizzando diversi indici ecologici strettamente correlatiall"arricchimento di materia organica ed ai gruppi trofici dei nematodi presenti nel terreno (Maturity Index e EnrichmentIndex). Nel corso del presente studio sono stati campionati tre diversi siti della regione Puglia, localizzati uno in una riservanaturale, il secondo in prossimità di una centrale elettrica a carbone e il terzo in prossimità di una discarica, e per ciascunodi essi è stata condotta l"analisi della nematofauna presente utilizzando sia approcci morfologici che molecolari. Il DNAtotale della nematofauna presente in ciascun campione è stato estratto e sottoposto ad amplificazione mediante PCR. Il geneper il 18S rRNA è stato utilizzato come marcatore molecolare in quanto in banca dati esistono molte sequenze del 18S, talida coprire l"intero phylum dei nematodi. Sono state determinate circa 100 sequenze per ciascun sito. L"analisi dellesequenze mediante BLAST ha permesso di classificare le sequenze ottenute a livello di genere, alcune delle quali sono stateidentificate anche a livello di specie. Gli indici ecologici sono stati calcolati sia per i dati morfologici che per i datimolecolari rivelando che i risultati dei due approcci sono sovrapponibili. I siti analizzati si sono rivelati più disturbati incorrispondenza della centrale elettrica e della discarica rispetto al sito nella riserva naturale. Questi risultati preliminaridimostrano che i nematodi sono sicuramente dei buoni indicatori dello stato di conservazione di un suolo.

Benzothiadiazole (BTH) acts as a priming agent in plant defence leading to a reduction in penetration and development of the root-knot nematode Meloidogyne incognita in susceptible tomato roots. Changes in lignin biosynthesis in the susceptible tomato cv. Roma following nematode infection and/or BTH treatment were investigated in comparison to the resistant cv. Rossol. Both untreated and BTH-treated susceptible infected roots (galls) showed an increased level of expression of lignin synthesis-related genes (PAL, C4H, HCT and F5H) at early times during infection (2-4 days post inoculation). Peroxidase (soluble and cell-wall bound, POX) enzyme activities increased after inoculation with M. incognita and the priming effect of BTH treatment was evident at later stages of infection (7 days post inoculation). As expected, the induction of PAL and POXs and lignin synthesis-related genes was faster and greater in resistant roots after infection. Histochemical analysis revealed accumulation of higher lignin levels at later infection stages in BTH-treated galls compared to untreated ones. Furthermore, the monomer composition of lignin indicated a different composition in guaiacyl (G) and syringyl (S) units in BTH-treated galls compared to untreated galls. The increase in G units made G/S ratio similar to that in the resistant genotype. Overall, lignin played a critical role in tomato defence to M. incognita in response to BTH.

Biocontrol effects of arbuscular mycorrhizal fungi against nematodes have been reported in various plants. Literature data suggest that mycorrhizal symbiosis affects plant-water relationships as well. Moreover, it is well established that water deficit and infection with plant parasitic nematodes represent two environmental stresses with interacting effects under field conditions. Few data are available on the effect of combined mycorrhizae and water stress on the development of nematode feeding sites. We studied the impact of Rizophagus intraradices symbiosis on Meloidogyne incognita and tomato (cv San Marzano nano) interaction, with or without water stress. Plants inoculated or not with R. intraradices, maintained in growth chamber at 25°C, were exposed to mild water stress and subsequently infected with J2s of M. incognita. Galls hand-dissected at 7 and 14 days were processed for light microscopy observations. The analysis performed on cross sections of galls i) with or without mycorrhizae, ii) with water stress and iii) with mycorrhizae and water stress, showed changes in the morphology of galls and nematode feeding sites, affecting density and dimensions of nuclei. The symbiosis with R. intraradices and water stress hampered development and structure of giant cells, showing an effect on the modulation of host plant metabolism. NGS-based analysis of galls transcriptome is under study, to unravel the molecular pathways involved in this multiple interaction. Research partially funded by CNR, Progetto Premiale Aqua.

Microorganisms play a key role in preserving soil fertility in forest agro-ecosystems.Arbuscular mycorrhizal (AM) fungi, which form symbioses with the roots of the most importantcrop species, are usually considered biofertilizers. AM fungi improve plant mineral nutrientacquisition, in exchange for C compounds derived from the photosynthetic process, which canresult in a positive host growth response and in an improved response to stress. Previous works,mainly performed in pots, suggest that the effects of the AM symbiosis on plant-water relationshipsare often subtle, transient, and probably circumstance- and symbiont-specific. Additionally, themechanisms involved in the mitigation to water stress effects on plant growth by AM fungi are stillto be elucidated. Within the framework of a project supported by CNR (AQUA), we studied theimpact of the AM symbiosis on tomato (var. San Marzano nano) tolerance to water stress. The firststep consisted in developing a protocol for water stress in presence/absence of an AM fungus. TwoAM species have been selected to be inoculated separately, i.e. Funneliformis mosseae andRizophagus intraradices, while non-mycorrhizal plants acted as controls. Leaf water potential(?leaf) and gas exchanges have been monitored until the plants reached a water stress state. Byvarying the duration of the drought, two levels of water stress were achieved, as confirmed by themeasurement of leaf water potential: moderate stress (water potential approximately -0.8 MPa) andsevere water stress (leaf water potential below -1.2 MPa), no stress (controls, leaf water potential at-0.3 MPa). Water Use Efficiency (WUE) has been calculated, showing a difference between the twoconsidered AM fungi. At the end of the experiment (when plants have reached a severe stress state),AM colonization degree has been calculated, and morphometric parameters have been considered(e.g., shoot length and diameter, internodal distance, stomatal density). For the followingbiochemical and molecular analyses, leaves and roots from all the set of plants have been collected.The levels of ABA, proline, H2O2 have been assessed, and the analysis of CAT and SOD activity isbeing determined. Gene expression analyses (RT-qPCR experiments) will be performed consideringgenes potentially involved in water stress response (e.g., a tomato gene coding for a dehydrin andLeNCED1) and in mycorrhizal symbiosis (e.g., fungal and plant PT genes), on leaves and rootsamples respectively. On the basis of the results so far obtained, R. intraradices has been selectedfor further experiments devoted to verify the impact of the AM symbiosis on the plant responses tobiotic stresses (i.e., aphids and nematodes) during drought conditions.

Annually significant tomato yield losses are caused by climate changes and pests and diseases attacks. Root-knot nematodes (Meloidogyne spp.) are the most damaging pests on the base of their wide distribution in tropic and sub-tropic climates and their wide host range. They modify host root tissue using effector proteins to create feeding sites as their source of nutrition. To develop alternative control strategies to nematode infections, we have considered aqueous ozone treatments (AOT) as a possible tool. Although gaseous ozone is phytotoxic, previous studies demonstrated that ozone in aqueous phase is effective to contain pests. The purposes of this study were to confirm the impact of AOT on tomato-M. incognita interaction and to analyse its role in plant defence response. Ozonated water was produced in situ by an ozone generator at 10 ppm and directly applied to tomato roots. Treatments were performed daily (10 ml/pot) for 4 days as soil drench on 14 days old tomato plants maintained in a growth cabinet (25 ± 2 °C). Nematode infection control by ozone treatments was set up by infecting untreated and treated plants with J2s of M. incognita. A number of plants were used 2, 4 and 7 days after nematode infection for biochemical and molecular analysis. Other plants were transferred in a glasshouse at 25 ± 2 °C and after 60 days they were uprooted and dry shoot and root fresh weights recorded. Root gall index, eggs and J2s/g root, total nematode population density and reproduction rate were evaluated. AOT significantly decreased severity of root gall index and soil nematode population in comparison to untreated plants. Tomato sensitivity to AOT was verified as reactive oxygen species production (ROS) in both treated and untreated root galls and compared with uninfected treated and untreated roots. A higher significant ROS production was observed in ozone treated uninfected roots in comparison to treated and untreated infected roots. As antioxidant mechanisms play an important role in the response of plant to the combination of abiotic and biotic stresses, the effect of AOT on the expression of different genes involved in ROS scavenging, such as CAT, SOD and APX, was also evaluated. AOT by altering gene expression, ROS production and inducing a non specific defense response can be considered a useful tool to contain nematode infection.Aknowledgement: This work was supported with funds provided by the National Research Council for the project "Innovazione e Sviluppo del Mezzogiorno - Conoscenze Integrate per Sostenibilità ed Innovazione del Made in Italy Agroalimentare".

Il particolato atmosferico (PM) è costituito da una miscela di particelle solide e liquide aventiorigine primaria e secondaria. La composizione chimica del PM varia notevolmente e dipende dafattori quali le fonti di combustione, il clima, la stagione e il tipo di inquinamento. Il PM è costituitoda particelle di materiale carbonioso, da composti organici volatili o semi-volatili adsorbiti sulleparticelle carboniose, da ioni, metalli di transizione, materiali di origine biologica e minerali. Seclassificato in base alla sua granulometria, il PM è distinto in "coarse" e "fine" e le due frazionicomprendono le particelle aventi rispettivamente diametro aerodinamico superiore e inferiore ai 2.5µm (PM2.5). Il particolato fine ed ultrafine è quello maggiormente associato agli effetti negativisulla salute umana perché può raggiungere le vie respiratorie più profonde fino ad arrivare aglialveoli polmonari, tuttavia non si può escludere la pericolosità delle particelle, caratterizzate dadiametro aerodinamico inferiore ai 10 µm (PM10). In generale gli effetti del PM sui diversiorganismi variano a seconda della concentrazione in atmosfera, delle loro caratteristiche fisicochimichee dal tempo di esposizione degli organismi a tale inquinante.In questo lavoro è stata studiata l'interazione del PM10 con tre differenti organismi. Estratti organicidi PM10 (EOM) e soluzioni standard di Idrocarburi Policiclici Aromatici (IPA) sono stati testatisugli organismi modello Rhodobacter (R.) sphaeroides 2.4.1 e Caenorhabditis elegans. Campionidi PM10 raccolti su filtri in fibra di quarzo sono stati utilizzati come supporto per la crescita dipiantine di pomodoro (Solanum lycopersicon). I risultati ottenuti indicano che gli effetti degliestratti organici di particolato atmosferico sono fortemente dipendenti dal tipo di organismo che adessi viene esposto. Mentre il C. elegans subisce un effetto negativo, con una mortalità fino al 50% apartire dal secondo stadio larvale (Liuzzi et al, 2012), l'esposizione di R. sphaeroides agli EOM nonmostra effetti dannosi, eccettuata una contenuta diminuzione della velocità di crescita. Le pianteesposte al particolato mostrano un evidente cambiamento nella morfologia dell'apparato radicale estress ossidativo rappresentato da un aumento del contenuto di radicali dell'ossigeno (ROS).

Sedentary endoparasitic root-knot nematodes (Meloidogyne spp.) are one of the most damaging pest in global agriculture. Various approaches, most focusing on the introduction of resistance genes in plants, have been undertaken to control these pathogens. Recently, plant activators provide an appealing management option by stimulating active plant defence mechanisms. One of the most interesting activators is benzo (1,2,3) thiodiazole-7-carbothioic acid S-methyl ester (BTH), which induces a broad spectrum, long lasting, and systemic immunity against different pathogens. The effect of the BTH pre-treatment in the compatible interaction tomato-Meloidogyne incognita was investigated. We found that BTH significantly reduces nematode reproduction and affects morphology of nematode feeding sites, thus enhancing resistance against infection.

Nematodes are widely recognised as bioindicators of the soil environment health. Analysis of soil nematode community is increasingly used to calculate various ecological indices related to enrichment and trophic status of nematofauna. The soil nematode community from three selected relatively undisturbed and disturbed sites in the Apulia region (Italy) was comparatively studied through both morpho-taxonomic and molecular analysis. Nematodes for both analyses were extracted from 100 g sub-samples from composite soil samples collected at each site. Nematodes were fixed in a 2.5% formaldehyde solution and thenidentified at family and genus level under an optical microscope. The maturity and trophic diversity indices were determined. For the molecular study, total DNA was extracted from the nematode community of each soil subsample and PCR amplification was performed by using the small subunit (18S) rDNA, as diagnostic marker, for nematode species discrimination. The 300 sequences available at this moment are still under characterisation. Sequencing of further 18S amplicons is also in progress.

Soil nematodes are organisms that quickly respond to changes (stress and pollutants) in the environment and can be useful ecological indicators of environmental disruption. Since they occur in any environment containing organic carbon, they do not quickly escape from stressful conditions, occupy key positions in soil food webs and can be classified in easily identifiable trophic groups (Bongers and Ferris, 1999). While there are many indices of biological diversity, specific tools have been developed for nematodes, such as the Maturity Index (MI) and the 3 Enrichment lndex (El). These indices are based on an ecological classification where to each taxonomic family is assigned an ecological value that ranges from l (typical families of polluted soils or sediments) to 5 (typical families of soils or sediments). The lower values (1 and 2) belong to colonizer nematodes (c), i.e. opportunists, characterized by a rapid biological cycle and able to quickly invade unstable or polluted habitats. High values (3 to 5) belong to persister nematodes (p), characterized by a slow reproduction rate. Persisters are more sensitive to pollutants and 1 other disturbances than colonizers, therefore MI also serve to measure the impact of mixtures of pollutants and the effect of their complex interactions with biotic and abiotic environment. The aim of this study was to identify the nematofauna, recovered from three different habitats, at morphological and molecular level to provide useful information on the soil features and any possible disturbances by calculating ecological indexes of soil biodiversity

Few studies have been carried out on the effect of ozonated water (O3wat) on the oxidative stress of root systems and, in particular,in combination with biotic stress. The aim of this study was to determine whether aqueous ozone is effective in the control of root-knot nematode (RKN) infection and to investigate the concomitant changes in the basal defence system. A tomato cultivar susceptible to Meloidogyne incognita was treated with O3wat as a soil drench. No negative effects were seen following ozone application in comparison with the control under the exposure conditions used. The treatment reduced significantly the nematode infection rate and induced changes in the morphology of nematode feeding sites, some of which were characterized by visible symptoms of senescence. The antioxidant response, as well as parameters of oxidative damage, were examined in untreated and Owat-treated galls at 2, 4 and 7 days after inoculation and compared with uninfected roots. High levels of reactive oxygen species (ROS), H32O and malondialdehyde were generated in galls in response to combined abiotic and biotic stresses. Throughout the experimental period, the activities and relative transcript levels of the antioxidant enzymes catalase, superoxide dismutase and ascorbate peroxidase produced different responses when exposed to ozone treatment and/or infection. The results demonstrate how O32wat protects tomato against the RKN M. incognita through the modulation of basal defence mechanisms.

Aqueous ozone treatments were applied to tomato plants (cv. Roma VF) before and after Meloidogyne incognita infection in controlled growth conditions. Ozonated water was produced in situ by an ozone generator at 8 ppm. Treatments were applied for 3 and 4 days as soil drench at the rate of 10 ml/pot (50 ml). Untreated plants were used as control. The sensitivity to aqueous ozone treatments was verified by the production of reactive oxygen species (ROS) in roots. A significant ROS production was observed after two days of ozone treatments in comparison to the untreated plants, without adversely influencing the growth of the treated plants. Visual examination of the root systems revealed no symptomatic evidence of root browning or other damages indicative of oxidative stress. Tomato plants infected with M. incognita before and after ozone treatments were grown in a glasshouse at 25 ± 2°C. After 60 days the plants were uprooted, and dry shoot and root fresh weights were recorded. Root gall index, eggs and juveniles/g root, total nematode population density and reproduction rates were evaluated. Root gall index was assessed according to a 0-10 scale, whereas nematodes were extracted from roots and soil by centrifugation and the Coolen's method, respectively. Reproduction rate was calculated by the ratio between final and initial nematode population density (r =Pf/Pi). Data from the experiments were subjected to ANOVA and means compared by Least Significant Difference's test. Root gall index, eggs and juveniles/g root, total nematode population density and the reproduction rate were significantly reduced in both ozone treatments (3 and 4 days of treatments), either before or after nematode inoculation, in comparison to the untreated control.

Nitric oxide (NO) has been shown to be an essential regulatory molecule in plant response to pathogen infection in synergy with reactive oxygen species (ROS). At the present, nothing is known about the role of NO in disease resistance to nematode infection. To investigate the key components involved in oxidative and nitrosative metabolism, experiments were carried out at different infection times by using a resistant tomato cultivar with different sensitivity to avirulent and virulent populations of the root-knot nematode Meloidogyne incognita. We analyzed the superoxide radical (O2.-) production, hydrogen peroxide (H2O2) content, and nitric oxide synthase (NOS)-like, and nitrate reductase (NR) activities, as potential sources of NO. A rapid NO accumulation and ROS production were differently linked to incompatible and compatible tomato-nematode interactions. NOS-like arginine-dependent rather than NR was the main source of NO production, and NOS-like activity increased substantially in the incompatible interaction. We can envisage a functional overlap of both NO and ROS in tomato defence response to nematode invasion, NO and H2O2 cooperating in triggering hypersensitive cell death. The results obtained from this studies reveal a defence mechanism that has not been previously described in tomato-nematode interaction and provide new insight into the complex regulation of ROS and NO metabolism by avr- and vir- RKN pathotypes in their hosts roots.

Nitric oxide (NO) has been shown to be an essential regulatory molecule in plant response to pathogen infection in synergy with reactive oxygen species (ROS). At the present, nothing is known about the role of NO in disease resistance to nematode infection. We used a resistant tomato cultivar with different sensitivity to avirulent and virulent populations of the root-knot nematode Meloidogyne incognita to investigate the key components involved in oxidative and nitrosative metabolism. We analyzed the superoxide radical production, hydrogen peroxide content, and nitric oxide synthase (NOS)-like and nitrate reductase activities, as potential sources of NO. A rapid NO accumulation and ROS production were found at 12 h after infection in compatible and incompatible tomatonematode interactions, whereas the amount of NO and ROS gave different results 24 and 48 h after infection amongst compatible and incompatible interactions. NOS-like arginine-dependent enzyme rather than nitrate reductase was the main source of NO production, and NOS-like activity increased substantially in the incompatibleinteraction.We can envisage a functional overlap of both NO and ROS in tomato defence response to nematode invasion, NO and H2O2 cooperating in triggering hypersensitive cell death. Therefore, NO and ROS are key molecules which may help to orchestrate events following nematode challenge, and which may influence the host cellular metabolism.

Urban particulate matter (PM) can affect green plants either via deposition on the above-ground biomass, where the contaminants can penetrate the leaf surface, or indirectly via soil-root interaction. In our investigation, a model experiment was carried out to demonstrate the direct effect of PM on tomato (Solanum lycopersicum L.) plant growth. A monitoring campaign of PM10 was conducted at an urban background site of Canosa (Apulia, Southern Italy) in four different days (1, 2, 3, 4). PM10 samples were collected for 24 hours on quartz fiber filter. The filters were then cut into two parts, one of which was used for the chemical characterization of the PM10 and one for the growth of tomato. Organic and elemental carbon and polycyclic aromatic hydrocarbons (PAHs) content were analysed for all the tested filters. Tomato plants were grown for 18 days directly on filters absorbed with PM10. The germination rate of tomato seeds and some parameters of seedlings primary growth of this plant species (length of root and shoot, their fresh weight and content of photosynthetic pigments in shoot) were used as laboratory indicators of phytotoxicity. Substantial differences were found in the growth of root apparatus respect to that of control plants. A significant decrease of primary root elongation, a large amount of secondary roots and a decrease in plant and root weights were found. To assess if the direct exposition of roots to PM10 induced an oxidative stress, reactive oxygen species (ROS) concentration was evaluated by measuring the fluorescence arising from oxidation of DCFH-DA in both control and treated roots. Quantitative analysis of ROS indicated that an oxidative burst in response to abiotic stress occurred in roots directly grown on PM10, whose detrimental effect was also confirmed by the findings on chlorophyll content and chlorophyll-to-carotenoid ratio.