1,721,069 research outputs found
Occurrence of Xanthomonas arboricola pv. corylina on hazelnut orchards in Sardinia and Sicily
No full textIn the course of field surveys carried out in hazelnut
(Corylus avellana) orchards of Sardinia [Barbagia di Belvì
(Nuoro)] and Sicily [Nebrodi (Messina) and Etna (Catania)]
symptoms resembling those incited by Xanthomonas
arboricola pv. corylina Vauterin et al. were observed.
Brownish, elliptical, water-soaked necrotic spots were
present on fruit husks and, sometimes, twigs showed partial
die-back. Tissues from lesion margins were ground in
a mortar containing physiological sterile saline. Aliquots
(0.1 ml) of serial ten-fold dilutions of the homogenate
were plated on Yeast extract-dextrose-calcium carbonate
agar and incubated at 25-27°C for three days. The resulting
circular, mucoid, yellowish colonies were subjected to
biochemical and pathogenicity tests, as well as repetitivesequence
PCR and fluorescent AFLP analysis in comparison
with the reference strain of X.a. pv. corylina NCPPB
2896 (National Collection of Plant Pathogenic Bacteria,
York, UK). All isolates from Sardinia and Sicily were
starch and esculin-positive, had an oxidative glucose metabolism,
and grew at 35°C. Genetic fingerprinting
showed a strong similarity of the isolates with NCPPB
2896. Pathogenicity tests, made according to Scortichini
et al. (2002), showed that all tested isolates induced wilting
of inoculated hazelnut twigs. Re-isolations yielded the
same colony type as in the primary isolations. We conclude
that the agent of the disease observed in hazelnut
orchards in Sardinia and Sicily is X. a. pv. corylina. This is
the first report of this pathogen in both islands.
Scortichini M., Rossi M.P., Marchesi U., 2002. Genetic, phenotypic
and pathogenic diversity of Xanthomonas arboricola
pv. corylina strains, question the representative nature of
the type strains. Plant Pathology 51: 374-381
Characterization of Xanthomonas campestris pv. vesicatoria from Capsicum annuum L. in Italy
No full text
Records of Pseudomonas syringae pv. actinidiae on Actinidia spp. in Trentino (North-East Italy)
Full text linkDuring 2012-2015, extensive field surveys were performed in new and old kiwifruit orchards located in the province of Trento (North-East of Italy). Symptoms resembling those incited by Pseudomonas syringae pv. actinidiae (Psa) (i.e, leaf spotting, twig wilting) were observed mainly on Actinidia deliciosa cv. Hayward and in a new orchard planted with A. chinensis cv. Soreli. The incidence of the disease ranged from 1% to 80%, and some old Hayward orchards (i.e., 35 years old) resulted severely damaged. From all infected orchards, samples were collected and, subsequently, processed in the laboratory for isolation by following routinely procedures (Ferrante and Scortichini, 2009). Bacterial isolates were obtained from all infected kiwifruit orchards; they were identified according to the techniques described by Ferrante and Scortichini (2010). Upon repetitive-sequence PCR using BOX, ERIC and REP primer sets, their fingerprint pattern perfectly matched that shown by the pandemic Psa 3 strain CRA-FRU 8.43. In addition, with isolates representative of all the sites from where the samplings were obtained, pathogenicity tests were carried out by artificially inoculating one-year-old, pot-cultivated A. deliciosa cv. Hayward plants according to the techniques described by Ferrante and Scortichini (2009, 2010). All the isolates induced, upon 10-15 days from the inoculation, the leaf spot and wilting symptoms. On the basis of these results, we conclude that P. s. pv. actinidiae was the causal agent of the field symptoms observed in green-fleshed and yellow-fleshed kiwifruit orchards located in Trentino. This is the first record of the disease in this regio
A reappraisal of traditional apple cultivars from Southern Italy as a rich source of phenols with superior antioxidant activity
No full textFew literature data are available on the nutraceutical properties of little widespread local apple cultivars. Such lack of information prevents exploitation of these germplasms for genetic improvement of new cultivars and for the re-evaluation of local agricultural products, which may attract a large share of consumers oriented towards natural food evoking ancient flavours. In this work eight traditional apple cultivars of Southern Italy were analysed in terms of phenolic composition and free radical scavenging activity in comparison with commercial "Annurca" and "Gold Chief (R) Gold Pink*" cultivars. HPLC-UV-MS analysis of methanol extracts of the cultivars under examination showed significant differences in phenol distribution within the three main classes of hydroxycinnamates, dihydrochalcones, and flavan-3-ols. Such differences were found to be associated with the antioxidant activities as determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. A good correlation was observed between the percentage of reduced DPPH and the total phenol content (R = 0.79). Among all phenol classes, the flavan-3-ol content showed the highest correlation (R = 0.77). Almost all of the traditional cultivars examined exhibited a much higher phenol content (2- to 7-fold) and hydrogen donor activity (1.5- to 4-fold) than widely consumed cultivars like "Annurca" and "Gold Chief (R) Gold Pink*
Characterization of Bacterial Strains Isolated from Cankers and Exudates on Hazelnut in Sardinia
No full textIn the last three years several bacterial isolates have been obtained from cankers and exudates observed on “Tonda Gentile delle Langhe” and “Tonda Gentile Romana” hazelnut cultivars (Corylus avellana L.) cultivated in Sardinia (Italy). Ten representative isolates with fluorescent pigments on the medium B of King et al. (1954), hypersensitive reaction on tobacco leaves and variable levan production, were chosen for pathogenicity tests and serological and molecular characterization. All the isolates were pathogenic to hazelnut, bean, pepper, tomato and pear seedlings, albeit to differing extents. Eight out of ten caused watersoaking on bean pods, while they were weakly pathogenic on lemon fruits and young apricot, peach and walnut plants. No symptoms were observed on lilac and apple. All ten isolates were tested in ELISA. Six isolates reacted positively to an antiserum (NCPPB 281) against a Pseudomonas syringae type strain, while only five isolates reacted to an antiserum against P. savastanoi pv. phaseolicola. Repetitive PCR with ERIC and BOX primer sets showed that the isolates were different from Pseudomonas avellanae, P. syringae pv. syringae and P. savastanoi pv. phaseolicola. Biochemical and pathogenicity tests, molecular characterization and other comparative studies, showed the 10 isolates obtained in Sardinia belong to a new pathovar whose complete characterization is currently under way
Oxidative damage and cell-programmed death induced in Zea mays L. by allelochemical stress
Full text linkThe allelochemical stress on Zea mays was analyzed by using walnut husk washing waters (WHWW), a by-product of Juglans regia post-harvest process, which possesses strong allelopathic potential and phytotoxic effects. Oxidative damage and cell-programmed death were induced by WHWW in roots of maize seedlings. Treatment induced ROS burst, with excess of H2O2 content. Enzymatic activities of catalase were strongly increased during the first hours of exposure. The excess in malonildialdehyde following exposure to WHWW confirmed that oxidative stress severely damaged maize roots. Membrane alteration caused a decrease in NADPH oxidase activity along with DNA damage as confirmed by DNA laddering. The DNA instability was also assessed through sequence-related amplified polymorphism assay, thus suggesting the danger of walnut processing by-product and focusing the attention on the necessity of an efficient treatment of WHWW
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