Roberto Causin

Pesticides and fertility: an epidemiological study in Northeast Italy and review of the literature.

An increasing number of observations suggestive for a causal link between pesticide exposure and reproductive dysfunctions have appeared in literature during recent years. The present epidemiological analysis was undertaken to evaluate whether living in rural areas, where large amounts of pesticides are applied, represents a risk factor for infertility. Fertility rate (FR) was taken as statistical indicator for potential changes in fertility mediated by pesticides. The study analyzed a large population from an agricultural area of the North Eastern Italy, the Veneto Region. According to the estimated quantities of sprayed pesticides, the area was divided in three sub-areas with expected low, intermediate and high pesticide exposure. Comparisons of FR failed to detect significant differences among populations from the three selected areas, while regression analysis showed a significant decrease of FR relative to the total amount of pesticides used. Although several investigative shortcomings prevent the results from being conclusive, this study seemingly challenges the hypothesis that living in rural areas where large amounts of pesticides are applied represents a risk factor for fertility.

Fusarium Toxins in Cereals: Occurrence, Legislation, Factors Promoting the Appearance and Their Management

Fusarium diseases of small grain cereals and maize cause significant yield losses worldwide. Fusarium infections result in reduced grain yield and contamination with mycotoxins, some of which have a notable impact on human and animal health. Regulations on maximum limits have been established in various countries to protect consumers from the harmful effects of these mycotoxins. Several factors are involved in Fusarium disease and mycotoxin occurrence and among them environmental factors and the agronomic practices have been shown to deeply affect mycotoxin contamination in the field. In the present review particular emphasis will be placed on how environmental conditions and stress factors for the crops can affect Fusarium infection and mycotoxin production, with the aim to provide useful knowledge to develop strategies to prevent mycotoxin accumulation in cereals.

Changes in ectomycorrhizal diversity in a declining Quercus ilex coastal forest

Oak decline is generally accepted to be the result of a dynamic interaction between oaks and a mix of abiotic and biotic causes, within which environmental stresses (drought, salinity, frost, low fertility) may be important as predisposing factors. As a result of these interactions, trees gradually begin to show symptoms of general suffering, which below ground consist of functional and anatomical modifications to the rootlets and changes in the ectomycorrhizal status. The present study was performed in a coastal Quercus ilex forest, where decline symptoms appeared after heavy land reclamation in the adjoining areas, which caused a rapid lowering of the ground water level and the underground intrusion of seawater from the neighbouring Adriatic Sea into the forest itself. A forest survey including examination of rootlet features from asymptomatic and declining trees suggested that drought and salinity were involved in this decline. The relative frequency of the most recurrent ectomycorrhizal morphotypes distinguished clearly between asymptomatic, weakly declining and strongly declining trees, suggesting that the occurrence and distribution of only a limited number of morphotypes can give an indication of the severity of the decline. Moreover, of all the morphotypes observed only one third were found in all three decline classes, while the remaining two thirds were gradually replaced by others as the proportion of declining trees increased, where the number of morphotypes was greater. The hypothesis of an adaptive response of the ectomycorrhizal community to decline or to the predisposing factors of decline is discussed.

Transmission of grapevine Pinot gris virus by Colomerus vitis (Acari: Eriophyidae) to grapevine

Grapevine Pinot gris virus (GPGV) is a new virus reported in Europe and several other grape-growing countries. In an attempt to identify a vector for GPGV, samples of the eriophyid mite Colomerus vitis collected from buds and erinea in GPGV-infected vines were analysed by RT-PCR, using specific primers. Molecular analysis revealed the presence of GPGV in C. vitis. Transmission trials were conducted using C. vitis collected from GPGV-infected vines. Mites were able to transmit GPGV to healthy grapevines, suggesting that C. vitis is a potential vector of this virus.

A cDNA-AFLP approach to study ochratoxin A production in Aspergillus carbonarius

Aspergillus carbonarius is responsible for the majority of mycotoxin contaminations in grapes and its derivatives. Most of A. carbonarius strains are ochratoxin A (OTA) producers, even though at very different levels. This broad variability was used to identify genes whose expression is linked with the ability of producing OTA. A cDNA-AFLP differential display screening was performed in two strains of A. carbonarius, antagonists for the ability of producing OTA, allowing the identification of 119 differentially expressed sequences putatively involved in the regulation of OTA biosynthesis. A likely connection was pointed out between the biosynthesis of the toxin, vegetative growth and sexual/asexual developmental progression, along with common signalling pathways involving G protein and Ca2+/calmodulin dependent phosphorylation and dephoshorylation cascades.

TRICHODERMA HARZIANUM T22 INDUCES IN MAIZE SYSTEMIC RESISTANCE AGAINST FUSARIUM VERTICILLIOIDES

SUMMARY Fusarium verticillioides is one of the most common plant pathogenic fungi affecting maize causing ear and kernel rot. Nearly the totality of the fungal strains are able to produce mycotoxins known as fumonisins at very different levels. However, information on the ability of the biocontrol fungus Trichoderma harzianum to induce systemic resistance in maize against F. verticillioides is still lacking. We now show that, upon root colonization by T. harzianum, F. verticillioides consistently reduces maize disease symptoms. The enhanced activation of SA- and JA/ ET-dependent defence responses indicates that resistance in maize is caused by a better perception of the fungal pathogen due to the effect of Trichoderma inocula. Seed biopriming with T. harzianum could be a useful strategy to control F. verticillioides infection and fumonisin accumulation under field conditions.

In Vitro Production of Fumonisins by Fusarium verticillioides under Oxidative Stress Induced by H2O2

The effects of oxidative stress induced by H2O2 were tested in liquid cultures in the fumonisin-producing fungus Fusarium verticillioides. The quantitative analysis of fumonisins B1, B2, B3, and B4 was achieved by means of liquid chromatography coupled to high-resolution mass spectrometry. Two effects in F. verticillioides, consisting of different abilities to produce fumonisins in response to oxidative stress, were identified. Following H2O2 addition, two F. verticillioides strains produced significantly more fumonisin (>300%) while three other strains produced significantly less (<20%) in comparison to control cultures. Transcriptional studies with seven biosynthetic genes showed a significant increase in transcript levels in the strain that made more fumonisin and either no or minimal changes in the strain that made less fumonisin. Our data indicate the important role of oxidative stress toward the modulation of the fumonisin biosynthesis and suggest the necessity to verify the presence of such divergent behavior in F. verticillioides populations under natural conditions.

A Twig Canker on Russian Olive Caused by Phomopsis arnoldiae in Italy

In June 2002, open, irregularly shaped cankers on stems and twigs of Russian olive (Eleagnus angustifolia L.) were observed in central Italy in two neighboring experimental walnut timber plantations (i.e., Juglans regia L. or J. nigra L. grown with Alnus glutinosa L. and E. angustifolia as nitrogen-fixing plants). Foliage distal to the cankers appeared chlorotic and wilted and occasionally desiccated. No fungal, fruiting bodies were present on or near the canker surface, nor were symptoms were observed on root collars or roots. Radial sections through the cankers revealed dark brown discoloration of xylem, and microscopic examination showed that vessels frequently contained tyloses and mycelium. Four symptomatic plants were selected, and from each of these plants, isolations were made from one canker. From the necrotic margin of each canker previously surface-sterilized with 2% sodium hypochlorite and rinsed, two chips, 3-mm-wide, were placed on potato dextrose agar (PDA) and incubated at 20 ± 1°C for 8 days in the dark. Among a variety of microorganisms isolated were Coniothyrium fuckelii Sacc., Penicillium spp., and Phomopsis arnoldiae B. Sutton (3). Artificial inoculations were made on 3-year-old, container-grown E. angustifolia seedlings using two isolates each of the three fungi. Where the stems measured 5 mm in diameter, the bark was surface sterilized with 2% sodium hypochlorite, rinsed, wounded with a 3-mm-diameter cork borer, inoculated with a PDA disk containing mycelium and spores, and the wound sealed with Parafilm. Controls were treated the same way but with sterile disks of PDA. Each treatment was replicated with 10 seedlings and incubated in the greenhouse (20 ± 2°C, 80% relative humidity, and 12 h of natural light per day) for 60 days. After 30 days, wounds treated with P. arnoldiae showed necrotic lesions that developed into small patches of dead bark that cracked forming cankers. Radial sections through the stem at the canker site from 10 plants (five per isolate) showed the presence of mycelium in the vessels, from which P. arnoldiae was reisolated. After 60 days, the cankers on the remaining 10 plants measured 8 to 14 mm long, and microscopic observations confirmed the presence of the fungus. No disease symptoms or mycelium in the inner tissues were observed in the control plants or in the plants inoculated with the other fungi. The pathogenicity test was repeated twice with the same results. Detailed descriptions of both fungal features in vitro (1,3) and symptoms on larger plants are available (2). To our knowledge, this is the first report of this disease in Italy. Further research is in progress since Russian olive in Italy is frequently grown in the nursery for agronomic purposes because of its nitrogen-fixing ability. Cultures of our isolates of P. arnoldiae, the identification of which was confirmed by the Centraal Bureau voor Schimmelcultures (Utrecht, the Netherlands), are preserved in the herbarium L. Montecchio (LMPa1 and LMPa2) in Padova. References: (1) R. H. Arnold and J. C. Carter. Mycologia 66:191, 1974. (2) W. A. Sinclair et al. Diseases of Trees and Shrubs. Cornell University Press, Ithaca, NY, 1987. (3) B. C. Sutton. The Coelomycetes. Commonwealth Mycological Institute, Kew, UK, 1980.

Effect of potential biocontrol agents selected among grapevine endophytes and commercial products on crown gall disease

The current strategies for the control of Agrobacterium vitis crown gall in grape are generally unsuccessful once the pathogen has established in vineyards. Experimental trials were conducted to evaluate the effectiveness of treatments based on non-pathogenic endophytes isolated from asymptomatic grapevines growing in vineyards with high incidence of crown gall and on microorganisms isolated from commercial products. Two-year in planta trials conducted on rootstocks treated with endophytic isolates showed the effectiveness of two bacterial endophytes, both in the genus Curtobacterium, and one fungal isolate in the genus Acremonium in reducing crown gall development. For the commercial biological control agents, Bacillus subtilis SR63 and Trichoderma asperellum T1 were the most effective strains against A. vitis, indicating commercial products could be reserves to draw upon to identify useful biocontrol agents. Based on the combination of data in this work, microorganisms, both endophytes and those formulated in commercial products, were identified that can potentially be exploited for the control of grapevine crown gall disease.

Hygrotermic Treatment of Chesnut Logs Infected with "Cryphonectria parasitica"

Due to the reduced availability of large-sized chestnut logs in Europe, many European timber industries currently get their supplies from non-European countries, mainly from the Caucasian region, which are often not immune to chestnut blight. Given the high risk of introducing new virulent strains incompatible with local hypovirulent ones, the European Union regulation requires that chestnut logs, imported from so-called “third party” nations where Cryphonectria parasitica is present, reach the European boundaries bark free: this prevents the production of veneers, which are highly remunerative, but whose first workmanship phases require barked logs. Following a multilevel investigation, the authors propose a stem-flow protocol that can devitalise the parasite in barked logs while preserving the commodity characteristics of the wood, through a fast, simple and low-cost treatment, that can be performed at the European borders whenever C. parasitica is or might be present.