Plants possess an innate immune system enabling them to defend themselves against pathogen attack. The accumulation of newly synthesized pathogenesis-related proteins (PRs) is one of the most studied inducible plant defence response. In this paper, we report on the characterization of a class I PR4 vacuolar protein from Arabidopsis, named AtHEL. The protein has a modular structure consisting of an N-terminal hevein-like domain (CB-HEL) and a C-terminal domain (CD-HEL) that are posttranslationally processed. Both domains show a strong antifungal activity, but they do not have chitinolitic properties. CD-HEL was found to be endowed with RNase, but not DNase activity. Molecular modeling carried out on both domains revealed that CB-HEL possesses a chitin binding site strictly conserved between hevein-type peptides and that the cavity involved in substrate interaction of CD-HEL do not show any residue substitution with respect to the orthologous wheatwin1 from wheat. Using a fishing for partners approach, CB-HEL was found to interact with a fungal fruiting body lectin. According to literature, we can hypothesize that CB-HEL could cross the pathogen hyphal membrane and that its interaction with a fungal lectin could knock out one of the weapons that the fungus uses.

The effect on ambient pH of Fusarium culmorum during its growth on mineral medium and in apoplastic fluids from infected wheat seedlings, and the effect on the production and activity of the enzymes pectin lyase (PNL) and polygalacturonase (PG), were investigated. Fungal development on a weakly buffered mineral medium in the pH range 5·0 -8·0, with pectin as the sole carbon source, led to pronounced alkalinization, reaching values above 8·0. The increase in ambient pH was accompanied by enhancement of total PNL activity. Pectin lyase secretion was detected at pH 5·0 as a single isoenzyme. An additional isoenzyme was apparent during the increase in medium pH. Polygalacturonase was detected as a single isoenzyme only during early growth on medium buffered at pH 5·0. At this stage, the initial medium pH of 5·0, corresponding to the optimum pH for PG activity, appeared to be the most suitable for the activation of early production of this enzyme. During growth in acidified yeast extract medium the fungus secreted ammonia and increased medium pH. Similarly, in apoplastic fluids from inoculated seedlings the concomitant ammonia accumulation and rise in pH were recorded. This trend was accompanied by an increase in PNL, which could therefore function at close to its optimal pH. The results suggest that during infection of wheat seedlings by F. culmorum , pH modulation can lead to PNL production and activity, thus promoting colonization of host tissue.

Ozone (O3) is currently employed in wineries as a sanitizing agent and is used to control microbial growth and infection. This molecule decomposes spontaneously to oxygen upon application and the use of ozonated water can represent an alternative for the control of pathogens in the vineyard. Entire canopies of Vitis vinifera (cv Vermentino) plants have been sprayed throughout the vegetative growth with water saturated with O3 to assess the effects of these treatments in reducing the microorganism population, and to evaluate if and how the oxidative stress, induced in the plant by this strong oxidizing agent, affects fruit development, the activity of the cellular antioxidant system, and the production of aromas by the grape berries at ripening. Ozonated water treatments resulted in a partial control of microorganism population, especially considering fungi. Furthermore, the treatments induced a slight delay in the technological maturity of grapes, a significant increase in antioxidant capacity and changes of aroma profile of the grapes at harvest, with an accumulation of monoterpenes. In general, ozonized water treatments showed promising results and seem to be a feasible protocol to be applied in the vineyard in order to reduce the use of chemicals.

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Melon represents the most widespread cucurbit in Italy. In recent years melon has been subjected to significant losses in yield and quality due to an increasing number of soil‐borne fungal diseases. The collapse of melon, caused by a complex of fungal pathogens, including Monosporascus cannonballus, Acremonium cucurbitacearum, Plectosporium tabacinum and Rhizopycnis vagum, represents one of most destructive diseases worldwide. The purpose of this study was to determine the occurrence of collapse throughout melon‐producing areas in Italy in recent years, to verify the identification of isolates collected, and to test their pathogenicity on melon and other cucurbits. Several fungi were isolated from symptomatic roots of melons in the Italian production areas. The identification was supported by PCR with a species‐specific primer and DNA sequence data. RFLP and sequence analyses showed the existence of a substantial homogeneity among Italian M. cannonballus isolates. Given the self‐incompatibility of these isolates it is impossible to ascertain vegetative compatibility groups (VGC) and consequently genetic relatedness cannot be studied. The frequency of isolation of fungal species varied with geographic locations, M. cannonballus being present mainly in Central Italy, while A. cucurbitacearum and P. tabacinum were most common in Apulia. In pathogenicity tests under greenhouse conditions M. cannonballus, A. cucurbitacearum and P. tabacinum caused collapse symptoms and root rots, whereas R. vagum was found to be a weak pathogen.

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The present paper describes new symptoms on Eucalyptus spp. in Central Italy associated with the fungal pathogen Pestalotiopsis biciliata. This fungal species has been previously recorded in Italy on grape associated with fruit rot. Artificial inoculation trials on leaves confirmed the pathogenicity of the fungus to Eucalyptus camaldulensis. P. biciliata is included in the list of Pestalotiopsis spp. responsible for leaf disease on eucalypts worldwide.

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