A strain of Ascochyta agropyrina var. nana, a fungal pathogen of the perennial weed Elytrigia repens, producedseveral toxins in a liquid medium, and its primary toxin, named agropyrenol, was characterized asa substituted salicylaldehyde on the basis of its chemical and spectroscopic properties. Its absolute stereochemistrywas determined by Mosher's method. Two other minor metabolites were isolated from thesame culture and named agropyrenal and agropyrenone, respectively. They were characterized as a trisubstitutednaphthalene carbaldehyde and a pentasubstituted 3H-benzofuranone, respectively, using thesame techniques. When assayed on leaves of several weed plants, i.e., Mercurialis annua, Chenopodiumalbum and Setaria viridis, agropyrenol proved to be phytotoxic, causing the appearance of necrotic lesions,agropyrenal was less active, while agropyrenone was inactive. None of the compounds showed antibiotic,fungicidal or zootoxic activity.

Antioxidant defence responses were evaluated in Chenopodium album plants treated with a mixture of the phytotoxins ascaulitoxin, 2,4,7-triamino-5-hydroxyoctandioic acid (ascaulitoxin aglycone) and trans-4-aminoproline, produced by the pathogenic fungus Ascochyta caulina, previously proposed as mycoherbicide for this noxious weed. The enzymatic and non-enzymatic effects of these phytotoxins on the ascorbate system and on catalase activity were assessed by evaluating their biological and specific activities through spectrophotometric and electrophoretic analyses. In addition, the oxidative status was monitored through evaluating H2O2 content during the time-course. The mixture of toxins induced high levels of H2O2 accumulation resulting in an oxidative burst in the plant cells. Ascorbate peroxidase and catalase had crucial roles in detoxifying H2O2. The persisting metabolic perturbations, however, led to severe necrosis and death of C. album plants. The induced H2O2 production may be generated by the fungus as part of its necrotrophic nature. This study explains the defence responses in C. album to the mycoherbicide, in particular, the ascorbate systems' components and H2O2 as an index of oxidative stress.

The first asymmetric total synthesis of both enantiomers of the natural products colletorin A and colletochlorin A is presented. The proposed methodology is based on the coupling reaction between highly substituted aromatic Gilman cuprates and optically active allyl bromides, in turn obtained by Sharpless asymmetric dihydroxylation. The latter ensured a high degree of regio- and stereocontrol in the enantioselective step of the synthesis. The same synthetic strategy has been also applied for the preparation of differently halogenated synthetic analogues of colletochlorin A in high enantiomeric purity. The enantioselective synthesis of colletorin A and colletochlorin A allows to reliably assign their absolute configuration. Preliminary assessment of their herbicidal and insecticidal properties evidence the possibility to modulate the bioactivity of these compounds, highlighting its dependence on both the absolute stereochemistry and the halogen nature. (C) 2018 Elsevier Ltd. All rights reserved.

Two new furopyrans, named chenopodolans E and F (1 and 2), were isolated from the liquid culture of Phoma chenopodiicola, a fungal pathogen proposed for the biological control of Chenopodium album, a common worldwide weed of arable crops. They were characterized using spectroscopic methods as 3-(3-methoxy-2,6-dimethyl-7aH-furo[2,3b]pyran-4-yl)-but-2-enoic acid methyl ester and 1-(3-methoxy-2,6-dimethyl-7aH-furo[2,3b]pyran-4-yl)-ethanone, respectively. Furthermore, the absolute configuration of chenopodolan B (3) was established to be (7aR,9S) by a combined application of the advanced Mosher's method and of quantum mechanical calculations of chiroptical (ECD and ORD) properties. When 1 and 2 were assayed on punctured leaves at 2??g/?L, only 2 was active on Sonchus arvensis while 1 caused around 75% larval mortality on Artemia salina larvae at 0.1??g/?L.

Three tetrasubstituted furopyrans, named chenopodolans A-C, were isolated together with the well known fungal metabolite (-)-(R)-6-hydroxymellein from the liquid culture of Phoma chenopodiicola, a fungal pathogen proposed for the biological control of Chenopodium album, a common worldwide weed of arable crops. The structures of chenopodolans A-C were established by spectroscopic and chemical methods as 2-(3-methoxy-2,6-dimethyl-7aH-furo[2,3-b]pyran-4-yl)- butane-2,3-diol, 1-(3-methoxy-2,6-dimethyl-7aH-furo[2,3-b]pyran-4-yl)ethanol and 3-methoxy-2,6-dimethyl-4-(1-methylpropenyl)-7aH-furo[2,3-b]pyran, respectively. The absolute configuration R to the hydroxylated secondary carbon (C-11) of the side chain at C-4 of chenopodolan A was determined by applying an advanced Mosher's method. Assayed by leaf puncture on host and non-host weeds chenopodolans A and B, and the 11-O-acetylchenopodolan A showed a strong phytotoxicity. These results showed that the nature of the side chain attached to C-4 is an important feature for the phytotoxicity. A weak zootoxic activity was only showed by chenopodolan B.©; 2013 Elsevier Ltd. All rights reserved.

A new tetrasubstituted indolylidenpyrandione named colletopyrandione (1), together with a tetrasubstituted chroman- and a tetrasubstituted isocroman-3,5-diol, named colletochlorins G and H (2, 3), respectively, were isolated from the culture filtrates of the fungus Colletotrichum higginsianum together with the already known colletochlorin A, 4-chloroorcinol, colletopyrone and colletochlorins E and F. Colletopyrandione and the two new colletochlorins (G and H) were characterized as (Z)-3-(3-hydroxy-3-methylindolin-2-ylidene)-5,6-dimethyl-pyran-2,4-dione, 8-chloro-2,2,7-trimethyl-chroman-3,5-diol and 8-chloro-1,1,7-trimethyl-isochroman-3,5-diol, respectively, by spectroscopic (NMR and HRESIMS) methods. The relative configuration of 1 was assigned by X-ray diffractometric analysis. Colletopyrandione was isolated as scalemic mixture and the absolute configuration of the most abundant enantiomer was assigned by ECD and VCD spectra combined with quantum-mechanical calculations. Assayed in several biological systems, colletopyrandione showed a modest phytotoxic activity, associated to a complete lack of toxicity towards off-target organisms.

A new tetrasubstituted pyran-2-one and a new dihydrobenzofuran, named colletochlorins E and F (1 and 2), were isolated from the culture filtrates of the fungus Colletotrichum higginsianum together with the already known colletochlorin A, 4-chloroorcinol and colletopyrone. Colletochlorins E, the main metabolite, and F were characterized by spectroscopic (NMR, HRESIMS) and chemical methods as 3-[7-chloro-4-hydroxy-2-(1-hydroxy-1-methylethyl)-6-methyl-2,3-dihydro-benzofuran-5-ylmethyl]-4-hydroxy-5,6-dimethyl-pyran-2-one, and 7-chloro-2-(1-hydroxy-1-methylethyl)-6-methyl-2,3-dihydrobenzofuran-4-ol. The absolute configuration 2?S of 1 was deduced by X-ray diffractometric analysis while that 2S of 2 was deduced by comparison of its NMR and CD data with those of 1. When assayed by leaf puncture on Sonchus arvensis and tomato leaves, 2 caused quite large necrosis (wider than 1 cm) while 4-chloroorcinol proved to be the most active compound. These results were confirmed to those obtained in the assay on Lemna minor and on Phelipanche ramosa seed germination. Furthermore, 1, colletochlorin A and colletopyrone were less and modestly active in the last assay, respectively. Interestingly, the phytotoxicity was not associated to an antibiotic activity while only 4-chloroorcinol, colletochlorin F exhibited zootoxic activity.

Ailanthus altissima (Mill.) Swingle (commonly named tree of haven, family: Simaroubaceae) is a very dangerous invasive plant species. The invasiveness of this dioecious species is due to its ability to reproduce, equally well, both by seed (one plant can produce thousands of "flying" samaras) and asexually (its extended and vigorous root system generates numerous suckers and progeny plants). The species is able to adapt to any type of soil and water regime. It spreads everywhere in urban and sub-urban areas, on roadsides, railways and ruins, in uncultivated or abandoned areas, gardens and green spaces. A. altissima plants reach the heart of natural areas causing severe ecological effects. Plants form highly dense stands outcompeting native species and reducing their growth. Thus this species represents a serious threat both in natural and anthropic areas.The management of A. altissima is very difficult. The most common methods include manual, mechanical and chemical control. Hand pulling can be carried out only on very young seedlings before the root system has developed. Mechanical removal (cut) is the most used technique in public areas but proved to be costly and quite ineffective, as it induces a faster development of suckers and resprouting shoots. Moreover, in urban and archeological areas the use of mechanical equipment can be very dangerous or even not practicable. Spray treatments of herbicides are frequently not allowed in urban and natural areas due to health and environmental risks. The Alta Murgia National Park is a very wide Park (over 68,000 ha) located in the Apulia Region (Southern Italy). It is a Site of Community Importance (SCI) and a Special Protection Area (SPA) within the EU Natura 2000 network. Within the Park, A. altissima is the most spread invasive plant species, and it is considered one of the most serious threat for the biodiversity. A project named "LIFE Alta Murgia" was funded in 2013 by the European Commission within the LIFE+ Framework, aimed at eradicating A. altissima from the Alta Murgia National Park by using innovative and eco-friendly control techniques, based on a minimized use of effective herbicides with environmentally friendly stem applications (e.g. stem injection, cut stump, spaced cut). In order to accurately take a census, map and quantify the infestation in the whole park, plan the interventions, manage the control program and check the progresses of the management practices, a ad hoc software was initially developed.In the present communication the procedures used and the results obtained in the weed mapping will be shown. Moreover, the first results regarding the control treatments and their effectiveness will be presented.

Common ragweed, Ambrosia artemisiifolia L. (Asteraceae), an annual weed native to Northern America, has become invasive in numerous countries in Europe. South-central and south-eastern European regions are the most affected. In the western and northern parts of Europe and mountain ranges ragweed does not behave as an invasive weed, yet. Climate change is expected to facilitate the establishment of ragweed as a self-propagating weed in these regions in the near future.The major concern regarding common ragweed is due to its highly allergenic pollen that causes sensitisation of the population, generating huge medical costs. Ragweed also has increasingly become a major weed in European agriculture, especially in spring-sown crops such as sunflower, maize, sugar beet and soya beans. Because of the taxonomic relatedness with sunflower, herbicides are of limited use in this crop, facilitating the spread of Ambrosia throughout Europe in birdseed, other feeding mixtures and crop seed. Herbicides and mechanical control (uprooting, cutting, ploughing) are best suited as local and short-term measures to eradicate initial and small populations, and to mitigate further spread of established populations. In other crops herbicide treatments may be sufficient to prevent yield losses, but often this in not sufficient to prevent ragweed populations from flowering and setting seeds. In non-agricultural land, management of ragweed using herbicides is too expensive and, furthermore, the need to protect the accompanying vegetation does not allow large-scale application of herbicides. Thus, the ragweed population is increasing.Bioactive fungal metabolites have been long considered for their potential direct use as natural herbicides, as a lead for new herbicides or to discover novel mechanisms of action. The authors of this article have a long history and a strong expertise in the production and chemical and biological characterization of novel bioactive metabolites from microorganisms and plants. However, despite the enormous number of novel metabolites identified and available in their labs, none of them has ever been tested against A. artemisiifolia. Thus, a number of selected metabolites produced and purified by the culture of pathogenic fungi and plants was used in preliminary tests to evaluate their effects on the germination of ragweed seeds, the elongation of seedling rootlets and on the development of necrotic spots on leaves. The present communication reports the first results of these biological assays, discussing the potential use of the most interesting metabolites as natural herbicides for ragweed management.

Inuloxin A is a promising plant phytotoxic sesquiterpene that deserve further studies to evaluate its potential as a bioherbicide. However, its low solubility in water and bioavailability could hamper its practical application. For this reason, inuloxin A was complexed with ?-cyclodextrins by using three different methods, i.e.: kneading, co-precipitation and grinding. The resulted complexes were fully characterized by different techniques as 1H NMR, UV-vis, XRD, DSC and SEM, and biologically assayed in comparison with the pure compound in several biological systems. The efficacy of the kneading and grinding complexes was similar to inuloxin A and almost completely inhibit the Phelipanche ramosa seed germination. The complete solublity in the water and the preservation of the biological properties of these two complexes could allow further studies to develop a novel natural herbicide for parasitic plant management based on these formulations.

Fungal phytotoxins are natural secondary metabolites produced by plant pathogenic fungi during host-pathogen interactions. They have received considerable particular attention for elucidating disease etiology, and consequently to design strategies for disease control. Due to wide differences in their chemical structures, these toxic metabolites have different ecological and environmental roles and mechanisms of action. This review aims at summarizing the studies on the possible use of thesemetabolites as tools in biological and integrated weed management, e.g. as: novel and environmentally friendly herbicideslead for novel compounds; sources of novel mechanisms of action. Moreover, the limiting factors for utilizing those metabolites in practice will also be briefly discussed.

Two new diterpenoid alpha-pyrones, named higginsianins A (1) and B (2), were isolated from the mycelium of the fungus Colletotrichum higginsianum grown in liquid culture. They were characterized as 3-[5a,9b-dimethyl-7-methylene-2-(2-methylpropenyl)dodecahydronaphtho[2,1-b]furan-6-ylmethyl]-4-hydroxy-5,6-dimethylpyran-2-one and 4-hydroxy-3-[6-hydroxy-5,8a-dimethyl-2-methylene-5-(4-methylpent-3-enyl)decahydronaphthalen-1-ylmethyl]-5,6-dimethylpyran-2-one, respectively, by using NMR, HRESIMS, and chemical methods. The structure and relative configuration of higginsianin A (1) were confirmed by X-ray diffractometric analysis, while its absolute configuration was assigned by electronic circular dichroism (ECD) experiments and calculations using a solid-state ECD/TDDFT method. The relative and absolute configuration of higginsianin B (2), which did not afford crystals suitable for X-ray analysis, were determined by NMR analysis and by ECD in comparison with higginsianin A. 1 and 2 were the C-8 epimers of subglutinol A and diterpenoid BR-050, respectively. The evaluation of 1 and 2 for antiproliferative activity against a panel of six cancer cell lines revealed that the IC50 values, obtained with cells reported to be sensitive to pro-apoptotic stimuli, are by more than 1 order of magnitude lower than their apoptosis-resistant counterparts (1 vs >80 mu M). Finally, three hemisynthetic derivatives of 1 were prepared and evaluated for antiproliferative activity. Two of these possessed IC50 values and differential sensitivity profiles similar to those of 1.

Management of plant parasitic nematodes with nematode predators, parasites or antagonists is an eco-friendly approach that may avoid the problems arisen by the use of toxic chemicals. Fungi belonging to Trichoderma spp. are well known in literature for their role in control of plant parasitic nematodes. Root-knot nematodes (RKNs), Meloidogyne spp., are obligate parasites that cause the formation of familiar galls on the roots of many cultivated plants. The interaction between the M. incognita motile second stage juveniles (J2s) and the isolate ITEM 908 of Tricoderma harzianum was examined in its effect on the nematode infestation level of susceptible tomato plants.To gain insight into the mechanisms by which ITEM 908 interacts with nematode-infected tomato plants, the expression patterns of the genes PR1 (marker of Salycilic Acid-depending resistance signalling pathway) and JERF3 (marker of the Jasmonic Acid/Ethylene-depending resistance signalling pathway) were detected over time in: i) untrreated roots; ii) roots pre-treated with the fungus;- iii) roots inoculated with the nematode; iv) pre-treated and inoculated roots.Infestation parameters were checked in untreated plants and plants treated with the fungus to test the effect of the fungus on nematode infestation level and to compare this effect with the expression of the genes PR1 and JERF3, involved in induced resistance.

The in vitro anticancer activity and toxicity of phyllostictine A, a novel oxazatricycloalkenone recently isolatedfrom a plant-pathogenic fungus (Phyllosticta cirsii) was characterized in six normal and five cancer cell lines.Phyllostictine A displays in vitro growth-inhibitory activity both in normal and cancer cells without actualbioselectivity, while proliferating cells appear significantly more sensitive to phyllostictine A than nonproliferatingones. The main mechanism of action by which phyllostictine displays cytotoxic effects in cancercells does not seem to relate to a direct activation of apoptosis. In the same manner, phyllostictine A seems notto bind or bond with DNA as part of its mechanism of action. In contrast, phyllostictine A strongly reacts withGSH, which is a bionucleophile. The experimental data from the present study are in favor of a bondingprocess between GSH and phyllostictine A to form a complex though Michael attack at C=C bond at theacrylamide-like system. Considering the data obtained, two new hemisynthesized phyllostictine A derivativestogether with three other natural phyllostictines (B, C and D) were also tested in vitro in five cancer cell lines.Compared to phyllostictine A, the two derivatives displayed a higher, phyllostictines B and D a lower, andphyllostictine C an almost equal, growth-inhibitory activity, respectively. These results led us to proposepreliminary conclusions in terms of the structure-activity relationship (SAR) analyses for the anticanceractivity of phyllostictine A and its related compounds, at least in vitro.

KEY MESSAGE: Salicylic acid-signaling pathway and ethylene biosynthesis were induced in tomato treated with Trichoderma harzianum when infected by root-knot nematodes and limited the infection by activation of SAR and ethylene production. Soil pre-treatment with Trichoderma harzianum (Th) strains ITEM 908 (T908) and T908-5 decreased susceptibility of tomato to Meloidogyne incognita, as assessed by restriction in nematode reproduction and development. The effect of T. harzianum treatments on plant defense was detected by monitoring the expression of the genes PR-1/PR-5 and JERF3/ACO, markers of the SA- and JA/ET-dependent signaling pathways, respectively. The compatible nematode-plant interaction in absence of fungi caused a marked suppression of PR-1, PR-5, and ACO gene expressions, either locally or systemically, whilst expression of JERF3 gene resulted unaffected. Conversely, when plants were pre-treated with Th-strains, over-expression of PR-1, PR-5, and ACO genes was observed in roots 5days after nematode inoculation. JERF3 gene expression did not change in Th-colonized plants challenged with nematodes. In the absence of nematodes, Trichoderma-root interaction was characterized by the inhibition of both SA-dependent signaling pathway and ET biosynthesis, and, in the case of PR-1 and ACO genes, this inhibition was systemic. JERF3 gene expression was systemically restricted only at the very early stages of plant-fungi interaction. Data presented indicate that Th-colonization primed roots for Systemic Acquired Resistance (SAR) against root-knot nematodes and reacted to nematode infection more efficiently than untreated plants. Such a response probably involves also activation of ET production, through an augmented transcription of the ACO gene, which encodes for the enzyme catalyzing the last step of ET biosynthesis. JA signaling and Induced Systemic Resistance (ISR) do not seem to be involved in the biocontrol action of the tested Th-strains against RKNs.

Il pre-trattamento radicale di piante di pomodoro con i due ceppi di Trichoderma harzianum ITEM 908 (T908) e T908-5 ha indotto una minore suscettibilità delle piante al nematode galligeno Meloidogyne incognita, indicata da una limitazione della riproduzione e del numero di nematodi che si sono sviluppati nelle radici. La possibilità che tale minore suscettibilità potesse essere causata da un'induzione delle difese della pianta è stata verificata misurando localmente nelle radici e sistemicamente nelle foglie l'espressione dei geni PR-1 e JERF3, marcatori delle vie molecolari di segnalazione dipendenti rispettivamente dall'acido salicilico (SA) e dall'etilene/acido jasmonico (ET/JA),. Nella normale reazione compatibile tra piante non trattate e nematodi si registrava una forte soppressione dell'espressione del gene PR-1, sia localmente che sistemicamente, e una maggiore espressione del gene JERF3, anche se solo nelle radici. Al contrario, quando le piante erano pre-trattate con i ceppi di Trichoderma, l'espressione del gene PR-1 non veniva più repressa dall'infezione dei nematodi, mentre non si osservava nessun effetto sull'induzione dell'espressione di JERF3. Nelle piante trattate con T908-5 veniva osservato addirittura un aumento dell'espressione di PR-1 dopo l'infezione. Negli stadi più precoci della colonizzazione delle radici da parte di Trichoderma (un giorno dopo il trattamento) e in assenza di infestazione di Meloidogyne si registrava un' inibizione sistemica di entrambe le vie di segnalazione. Al 5° giorno dopo il trattamento la via di segnalazione SA-dipendente era ancora inibita, mentre quella legata a ET/JA non era differente rispetto alle piante non trattate. Dal momento che l'infezione del nematode a radici di piante pre-trattate con i funghi antagonistici induce invece che reprimere l'espressione del gene PR-1, è pensabile che in presenza dei Trichoderma la pianta risponda all'attacco del nematode attivando meccanismi di Resistenza Sistemica Acquisita (SAR). E' ipotizzabile che l'interazione iniziale tra radici di pomodoro e i ceppi di Trichoderma usati in questo studio inizializzi (effetto "priming") le piante per la SAR, con la conseguenza che la difesa contro l'attacco del nematode risulta più rapida ed efficace che nelle piante non trattate, limitando così l'attacco dei nematodi. Tale immunizzazione dura nel tempo, dato che l'effetto del trattamento si protrae sino all'attacco della seconda generazione di larve che si schiude nel terreno 30 giorni dopo l'inoculo della prima generazione. La seconda generazione è in grado di penetrare nelle radici e svilupparsi, ma non è giunta a riproduzione negli esperimenti condotti, in quanto le piante sono raccolte 40 giorni dopo l'inoculo. La totalità delle larve penetrate e sviluppate nelle radici è stata calcolata essere il 30-35% inferiore nelle piante trattate con i due ceppi di Trichoderma rispetto a quelle non trattate.

Ophiobolin A (O-A) is a sesterpenoid with numerous biological activities, including potential anticancer effects. Its production at an industrial level is hampered due to inability of fungus Bipolaris maydis to biosynthesise it in vitro in large amount. Among the environmental factors regulating fungal metabolism, light plays a crucial role. In this study, the use of different light wavelength (light emitting diodes (LEDs)) was evaluated to increase the O-A production. The white light allowed the highest production of the metabolite. The blue and green lights showed an inhibitory effect, reducing the production to 50%, as well as red and yellow but at a lower level. No correlation between fungal growth and metabolite production was found in relation to the light type. A novel application of LED technologies, which can be optimised to foster specific pathways and promote the production of metabolites having scientific and industrial interest was proposed.

Ascochyta lentis var. lathyri has recently been reported to be the causal agent of Ascochyta blight of grass pea (Lathyrus sativus), a disease characterized by the appearance of necrotic lesions of leaves and stems. Considering the novelty of the pathogen and the possible involvement of secondary metabolites in symptom appearance, a study was carried out to ascertain the capability of this fungus to produce bioactive metabolites. Some phytotoxic phenols were isolated from the culture filtrates of the fungus. In particular, two new phytotoxic metabolites, named lathyroxins A and B, were characterized by spectroscopic methods as 4-(2-hydroxy-3,3-dimethoxypropyl)phenol and 3-(4-hydroxyphenyl)propane-1,2-diol, respectively, and the R absolute configuration of C-2 of their 2-dimethoxy- and 2,3-diol-propyl side chain was assigned. Moreover, other well-known fungal metabolites, namely, p-hydroxybenzaldehyde, p-methoxyphenol, and tyrosol, were also identified. Lathyroxins A and B showed interesting phytotoxic properties, being able to cause necrosis on leaves and to inhibit seed germination and rootlet elongation. Moreover, both of the new metabolites had no effect against bacteria, arthropods, and nematodes.

A strain of the pathogenic fungus Ascochyta lentis isolated from lentil (Lens culinaris) was studied to ascertain its capability to produce bioactive metabolites. From the culture filtrates were found three new anthraquinone derivatives, named lentiquinones A (1), B (2), and C (3), and the known lentisone. From the mycelium, four known analogues were identified, namely pachybasin (in larger amount), ?-hydroxypachybasin, 1,7-dihydroxy-3-methylanthracene-9,10-dione, and phomarin. Lentiquinones A-C were characterized by spectroscopic methods as 3,4,6-trihydroxy-8-methyl-2H-benzo[g]chromene-5,10-dione, 2,3,4,5,10-pentahydroxy-7-methyl-3,4,4a,10-tetrahydroanthracen-9(2H)-one, and its 2-epimer, respectively, and the relative configuration of the two latter compounds was deduced by X-ray diffraction data analysis. The absolute configuration of lentiquinones B and C was determined as (2R,3S,4S,4aS,10R) and (2S,3S,4S,4aS,10R), respectively, by electronic circular dichroism (ECD) in solution and solid state, and TDDFT calculations. When tested by using different bioassays, the novel compounds showed interesting activities. In particular, applied to punctured leaves of host and nonhost plants, the three new compounds and lentisone caused severe necrosis, with lentiquinone A being the most active among the new metabolites. On cress (Lepidium sativum), this latter compound proved to be particularly active in inhibiting root elongation. On Lemna minor all the compounds reduced the content of chlorophyll, with 1,7-dihyroxy-3-methylanthracene-9,10-dione being the most active. The new compounds, together with lentisone, proved to have antibiotic properties.

I funghi fitopatogeni possono essere interessanti agenti di controllo biologico delle piante infestanti. Moltospesso questi agenti patogeni producono, nel corso dello sviluppo della malattia, dei metaboliti secondari con interessantiattività biologiche, in particolare fitotossica. Tali fitotossine potrebbero essere utilizzati sia direttamente come erbicidi naturali,o come "base" per nuovi erbicidi sintetici dotati di nuovi meccanismi di azione. Nell'ambito del Progetto COST SMARTERsono stati presi in considerazione alcuni patogeni di Ambrosia artemisiifolia ed alcune tossine prodotte da altri agentifitopatogeni, di cui si farà breve cenno in questa comunicazione.

Ambrosia artemisiifolia L. is responsible for serious allergies induced on humans. Different approaches for its control were proposed during the COST Action FA1203 "Sustainable management of Ambrosia artemisiifolia in Europe" (SMARTER). Fungal secondary metabolites often show potential herbicidal activity. Three phytotoxins were purified from the fungal culture filtrates of Colletotrichum gloeosporioides, isolated from infected leaves of A. artemisiifolia. They were identified by spectroscopic and chemical methods as colletochlorin A, orcinol and tyrosol (1, 2 and 3). The absolute configuration 6'R to colletochlorin A was assigned for the first time applying the advanced Mosher's method. When assayed by leaf-puncture on A. artemisiifolia only 1 caused the appearance of large necrosis. The same symptoms were also induced by 1 on ambrosia plantlets associated with plant wilting. On Lemna minor, colletochlorin A caused a clear fronds browning, with a total reduction in chlorophyll content.

Safer and more environmentally friendly methods, including the use of natural substances, would be favorably considered for weed management, particularly in those habitats where the use of chemicals is restricted or banned. Ascochyta caulina, a proposed mycoherbicide for biocontrol of the weed Chenopodiumalbum, produces in liquid culture three main metabolites proposed as possible natural herbicides. Recently a research project,namedECO-VIA, initiated a series of studies aimed at developing the technologies to obtain a natural herbicide based on these bioactive metabolites. Particular attention was given to: maximizing toxin production; lowering the production costs; scaling up the production in fermentation systems; setting up a large scale purification method and identifying fast and inexpensive chemical methods to quantify toxins yields. The fungus proved to grow well and to produce up to 230 mgof toxins l_1 culture when grown for 5-10 days in shaken conditions, provided the initial inoculum was at least 105-106 conidia ml_1 of culture. Toxin production was improved by the addition of yeast extract to the medium. Given suitable inoculum and growth conditions, a stirred fermenter could be suitable for mass production of toxin.

A new phytotoxic geranylcyclohexenetriol, named phomentrioloxin, was isolated from the liquid culture of Phomopsis sp., a fungal pathogen proposed for the biological control of Carthamus lanatus, a widespread and troublesome thistle weed belonging to the Asteraceae family causing severe crop and pastures losses in Australia. The structure of phomentrioloxin was established by spectroscopic, X-ray, and chemicalmethods as (1S,2S,3S,4S)-3-methoxy-6-(7-methyl-3-methylene-oct-6-en-1-ynyl)-cyclohex-5-ene-1,2,4-triol. At a concentration of 6.85 mM, the toxin causes the appearance of necrotic spots when applied to leaves of both host and nonhost plants. It also causes growth and chlorophyll content reduction of fronds of Lemna minor and inhibition of tomato rootlet elongation. Finally, in preliminary bioassays, phomentrioloxin did not show any antibacterial, fungicidal, or zootoxic activities.

The main lipophilic phytotoxic metabolite was isolated from the culture filtrates of Pestalotiopsis guepinii, the fungus causing twig blight of hazelnut. The metabolite was spectroscopically identified as pestalopyrone, a pentaketide that it was originally identified as a minor toxin produced by Pestalotiopsis oenotherae. The toxic activity of pestalopyrone was compared with that of nectriapyrone, a structurally related monoterpenoid recently isolated from Phomopsis foeniculi, and that of the new dihydro-derivative of nectriapyrone. The high phytotoxic activity of nectriapyrone and its dihydro-derivative on three non host plants, showed that the double bond of the 1-methylpropenyl group at C-6 of the aromatic ring is inessential for its activity, while the much lower activity of pestalopyrone showed that the methyl group at C-3 of the same ring is an important structural feature. The high molecular weight hydrophilic phytotoxins produced by this fungus are reported for the first time.

Two phytotoxins were isolated from the liquid culture of Phoma chenopodiicola, a fungal pathogen proposed for the biological control of Chenopodium album, a common worldwide weed of arable crops. The two phytotoxins appeared to be a new tetrasubstituted furopyran and a new ent-pimaradiene. From the same culture a new tetrasubstituted isocoumarin was also isolated. These compounds were characterized by using spectroscopic (essentially 1D and 2D NMR and HR ESI MS) and chemical methods as 3-(3-methoxy-2,6-dimethyl-7aH-furo[2,3-b]pyran-4-yl)-but-2-en-1-ol (chenopodolan D, 1) (1S,2S,3S,4S,5S,9R,10S,12S,13S)-1,3,12-triacetoxy-2,hydroxy-6-oxo-ent-pimara-7(8),15-dien-18-oic acid 2,18-lactone (chenopodolin B, 3), and, 4,5,7-trihydroxy-3-methyl-isochroman-1-one (chenisocoumarin, 2) The absolute configuration of chenisocoumarin was assigned by applying an advanced Mosher's method through the derivatization of its secondary hydroxylated carbon C-4, while that of chenopodolan D by application of quantum mechanical calculations of chiroptical (ECD and ORD) properties. When assayed by leaf puncture against non-host weeds, chenopodolan D and chenopodolin B showed phytotoxicity while chenisocoumarin and the 9-O-acetyl derivative of chenopodolan D were inactive. These results confirm that the nature of the side chain at C-4 in chenopodolans, and in particular its hydroxylation, are important features for activity. The activity of chenopodolin B could also be explained by its possible hydrolysis to chenopodolin.

Nematodes of the genus Meloidogyne are obligate parasites that infect a wide range of different crops in all agricultural regions worldwide and cause significant losses of both yield and quality of produce. Trichoderma spp. have long been known to be a feasible biological alternative to chemicals for control of several soil-borne plant pathogens. More recently, it has been shown that Trichoderma spp. may be effective also in control of plant parasitic nematodes. However, very little is known on the mechanism(s) by means of which these antagonistic fungi can limit nematode infestation. In order to assess the capability of the antagonistic strain T. harzianum ITEM 908 to elicit resistance to M. incognita in tomato plants, we investigated the expression of the genes PR-1 (marker of the salicylic acid-depending resistance signalling pathway, SAR) and JERF3 (marker of the jasmonic acid/ethylene-depending resistance signalling pathway, ISR) during the interaction between ITEM 908 and M. incognita on susceptible tomato plants. Our findings suggest that jasmonic acid/ethylene-mediated resistance to M. incognita, is induced in tomato roots by treatment with T. harzianum ITEM 908, whereas, salicylic acid-mediated resistance, seems not to be involved in the interaction between this strain and tomato plants, at least in the roots. We also investigated the effect of T. harzianum ITEM 908 on infestation parameters, such as egg mass production, female fecundity and reproduction potential of M. incognita on the infested tomato roots. The presence of a suitable amount of T. harzianum ITEM 908 in soil (106 CFU/g of rhizosphere soil) significantly reduced all of the infestation parameters investigated. It is still to be established whether nematode infestation is reduced by ISR induction in roots or by a putative nemato-static and/or nemato-toxic activity of ITEM 908 in the soil, or a combination of both.