Ernesto Lahoz

Fungistatic activity of iron-free bovin lactoferrin against several fungal plant pathogens and antagonists

Lactoferrin (LF) is a member of the transferrin family of iron-binding glycoproteins. It is also a multifunctional protein of 80 kDa that is synthesized by glandular epithelial cells and secreted into mucosal fluid. High levels of LF are present in colostrom and milk and low levels in tears, saliva, and gastrointestinal and reproductive secretions. Data regarding the antifungal effects of LF are limited. Studies have been performed on Candida albicans, which demonstrated that LF inhibits the growth of this fungus. This study reports the results of experiments carried out in order to evaluate the effects of LF on the growth of 11 fungi, which were isolated from plants and soils. These experiments employed the methods of amended agar utilizing nine different concentration levels of LF (0, 0.001, 0.01, 0.1, 1, 10, 100, 1000, 5000 mg L−1). The effects of LF on the growth of these fungi were based on measures of the radial growth of the fungal colonies expressed both as percentage of inhibition and as IC50 values (the concentration at which the fungal growth was inhibited by 50% relative to controls). LF had no effects on Alternaria alternata, Gliocladium roseum, Fusarium solani and Colletotrichum lindemuthianum. It did, however, inhibit the growth of Aspergillus niger, Trichoderma viride, Sclerotinia sclerotiorum, Sclerotium rolfsii, Rhizoctonia solani and Phoma exigua to the point that their IC50 values ranged from 31.1 mg L−1 for S. sclerotiorum to 952 mg L−1 for T. viride.

Fungistatic activity of Zanthoxylum rhoifolium Lam. bark extracts against fungal plant pathogens and investigation on mechanism of action in Botrytis cinerea

Plant-derived compounds are emerging as an alternative choice to synthetic fungicides. Chloroform–methanol extract, obtained from the bark of Zanthoxylum rhoifolium, a member of Rutaceae, showed a fungistatic effect on Botrytis cinerea, Sclerotinia sclerotiorum, Alternaria alternata, Colletotrichum gloeosporioides and Clonostachys rosea, when added to the growth medium at different concentrations. A fraction obtained by gel separation and containing the alkaloid O-Methylcapaurine showed significant fungistatic effect against B. cinerea and S. sclerotiorum, two of the most destructive phytopathogenic fungi. The underlying mechanism of such an inhibition was further investigated in B. cinerea, a fungus highly prone to develop fungicide resistance, by analysing the expression levels of a set of genes (BcatrB, P450, CYP51 and TOR). O-Methylcapaurine inhibited the expression of all the analysed genes. In particular, the expression of BcatrB gene, encoding a membrane drug transporter involved in the resistance to a wide range of xenobiotic compounds, was strongly inhibited (91%).

OVERCOMING OF THE RESISTANCE IN RESISTANT GENOTYPES OF DRY PEA (PISUM SATIVUM) BY AN ISOLATE OF ERYSIPHE PISI IN ITALY

Powdery mildew (PM), caused by Erysiphe pisi DC, is the major disease of dry pea in southern Italy and the use of resistant cultivar is the best choice to control it. Screening field trials were conducted with eleven pea genotypes in four different farms located in the typical pea-growing areas of the Campania region (Scafati, Caserta, Acerra and Eboli). All resistant varieties showed no symptoms in three (Scafati, Acerra and Eboli) of the tested environments, whereas at Caserta, three of the cultivars i.e. Fallon, SW Carousel, and ISCI 7/06-2, which are reported to carry the powdery mildew resistance gene er1 showed symptoms, whereas the resistance of cv. Stirling was confirmed. Following artificial inoculation under greenhouse conditions, the three above cultivars supposed to carry er1 gene showed severe PM symptoms when exposed to the fungal isolate EpCE2 from Caserta. No symptoms were obtained with the other three isolates tested. The cv. Stirling maintained its resistance both in the field and greenhouse. Morphological and molecular analyses of the fungus that induced disease on resistant cultivars proved that the isolates used as inoculum belong to E. pisi. This result was confirmed by the molecular analysis performed on the leaves of resistant cvs Fallon, SW Carousel and ISCI 7/06-2 inoculated with the EpCE2 isolate from Caserta. Thus, the resistance conferred by the er1 gene can be broken and further investigations are needed to clarify the different behavior of resistant cultivar. To our knowledge, this is the first time that breaking of er1 resistance is reported in Italy.

Characterization and pathogenicity of Pestalotiopsis uvicola causing black leaf spot on carob (Ceratonia siliqua L.) in Italy

During spring 2013, several carob plants (Ceratonia siliqua L.), showing symptoms of necrotic black lesions on leaves, were observed in Capri Island, Southern Italy. Acervuli, producing conidia with septa and appendages, appeared in the centre of the lesions. In this report, the identification of the causal agent of this disease was made applying Koch’s postulates. Morphological characteristics of colony (colour and mycelium appearance) and conidia (size, shape, number of septa, length and number of apical and basal appendages) were characterized to identify the pathogen. Moreover, for a rapid and unambiguous identification of the fungal species, the internal transcribed spacers, comprising the 5.8 rDNA gene (ITS1-5.8-ITS2), were amplified by PCR, using the genomic DNA extracted from the isolated colonies, and sequenced. The fungus isolated was ascribed to the species Pestalotiopsis uvicola (Speg.) Bissett. Phylogenetic analysis, performed with sequences present in GenBank database, showed that carob isolates clustered with P. uvicola isolates from North America and Italy, separately from Australian, Indian and Chinese isolates. P. uvicola isolates were pathogenic when artificially inoculated on carob leaves. To the best of our knowledge, this is the first report of P. uvicola on carob.