Genotypic and bio-agronomical characterization of an early Sicilian landrace of globe artichoke

In Sicily, the increasing use of exotic globe artichoke germplasm is eroding the presence of autochthonous landraces, including the long established ‘Violetto di Sicilia’. Ten clones have emerged from a clonal selection programme in this landrace, and here we describe the variation that they capture both at the level of AFLP-based genotype and phenotypically with respect to key productivity traits, on the basis of two seasons of field evaluation. The clonal selections yielded, on average, 8.9 heads per plant (equivalent to a fresh weight yield of 1.28 kg). Two clones yielded particularly well in both growing seasons (10.6 heads, equivalent to 1.46 kg per plant), while another pair produced particularly large heads (on average 165 g) and a high receptacle incidence (on average 19.3 g 100 g⁻¹ fresh weight). Both the number of days to first harvest and the quantity of head dry matter were subject to a significant degree of ‘clone × year’ interaction. Yield, the number of heads per plant and receptacle incidence were associated with a moderate (0.30–0.53) broad sense heritability, indicating that these traits could be successfully improved by phenotype-based clonal selection. AFLP fingerprinting was able to discriminate between all the clones, based on only three primer combinations. A principal component analysis based on the AFLP fingerprints was used to compare the selected clones with a set of individuals chosen on the basis of maximum genetic diversity. This comparison suggested that the new clone set was representative of the genetic variation present in ‘Violetto di Sicilia’, because the diversity captured by the two sets was largely overlapping, confirming the possibility of carrying out clonal selection in this globe artichoke landrace without compromising its preservation in situ.     

Development of Real-Time PCR for in wood-detection of Ceratocystis platani, the agent of canker stain of Platanus spp.

Ceratocystis platani is a quarantine fungal pathogen agent of canker stain, a destructive disease affecting Platanus. Despite its diagnosis being critical for disease control, there is still no effective diagnostic tool as all known mycological and biological detection assays are problematical. In this study we developed highly effective Real-Time PCR methods based on the use of an intercalating dye, EvaGreen, and on a Taqman probe. We designed primers and probe on the internal transcribed spacer (ITS) region of rDNA, and used them for the amplification and detection of a 95?bp C. platani amplicon. Inference of standard curves revealed that both Real-Time procedures have similar and high values of amplification efficiency when applied to a range of templates, e.g. genomic fungal DNA and DNA extracted from diseased wood. The methods were sensitive with a detection limit of 10?fg???l^?1? C. platani genomic DNA. They were specific as they did not yield any detection signal when applied to non-target fungal taxa colonizers of Platanus wood. Reliability was demonstrated through the positive detection of a collection of C. platani isolates and of wood samples collected from naturally infected trees. Robustness was positively verified through detection on artificially infected trees, which were tested at different times after death, up to 27?months. Generating a standard curve with a target-amplicon-containing plasmid enabled an absolute quantification and a comparison between the discoloured wood of resistant and susceptible genotypes. The importance of the methods for studies on pathogen epidemiology and host resistance is also discussed.     

Prevalence and risk factors of astrovirus infection in puppies from French breeding kennels

Aiming at determining the prevalence and the risk factors associated to astrovirus infection in puppy, fecal samples were collected in 316 puppies (age from 5 to 14 weeks of age) from 33 French breeding kennels. Data were registered for each puppy, including age, breed, gender, origin of the dog, and feces quality. The samples were tested by specific RT-PCR for the presence of canine astrovirus. Astroviruses were identified in 20.9% (66/316) of the puppies and in 42% (14/33) of the breeding kennels. Young puppies (i.e. <7 weeks of age) and puppies from large breeding kennels were more likely to be infected by the astrovirus. No association between the quality of feces and astrovirus infection could be determined in this survey.     

Molecular genotyping of Salmonella enterica Abortusovis by pulsed field gel electrophoresis

Genotyping of Salmonella strains is an important tool to discriminate among isolates and to improve epidemiological studies when an outbreak occurs. No phagetyping scheme is available for Salmonella enterica subsp. enterica serovar Abortusovis (SAO) and molecular methods previously used were not standardized and were time consuming. Among the DNA-based methods of genotyping, pulsed field gel electrophoresis (PFGE) is currently in use to subtype Salmonella isolates. In this study we evaluated the feasibility of genotyping of SAO by XbaI and BlnI restrictions. Separation of restricted fragments was performed by PFGE. To test the possibility to apply this methodology to epidemiological investigation, a collection of 38 SAO strains isolated in different regions of Italy were analyzed. Eighteen and 29 different PFGE profiles were defined for XbaI and BlnI digestions, respectively. The method demonstrated an adequate typing ability and an excellent discriminatory power. Results from this study show that PFGE may represent a powerful tool to discriminate within the SAO serovar, and provide useful information in support of traditional epidemiological investigations. In particular, this method could be used to identify the origin of infection during outbreaks within a single flock or in different herds.     

Book reviews

Agriculture and Human Values -     

Residents and urban green spaces: The case of Bari

The total area of public green spaces in the city of Bari, Italy is more limited than in most other Italian cities (2.9 m²/inhabitant). This fact makes it an interesting subject for research into the general perception that the residents of the city have of green spaces and their behaviour patterns when using them.

A questionnaire (27 questions) was presented by telephone to a representative sample (n=351) of the population of Bari. The aims of the study were: (a) to gain insight in the perception of green spaces with particular reference to those green areas within the city itself; (b) to examine behaviour during visits to parks and gardens and means of transport used to reach them; (c) to investigate what kind of relationship should be set up between the local authority and the population regarding information and participation.

The results show that respondents perceive the green areas as a life quality enhancer in accordance with some previous studies carried out in Italy and in other countries. Citizens are moreover conscious of the limitations in quality and quantity of green areas in their own city, although this result needs to be more closely analysed in the future. Patterns in the use of public green areas proved to be strictly connected with age, sex, marital status, area of residence. Another conditioning factor was the system of mobility. The results moreover underline how citizens see the public and private green areas as single beneficial system.

The research also demonstrates the potentials of applying telephone surveys in studies concerning urban forests.     

Tissue culture methods for the screening and analysis of putative virus-resistant transgenic potato plants

ABSTRACT Following regeneration, putative virus-resistant transgenic plants are usually transferred from tissue culture to a greenhouse or growth chamber to screen for resistance to infection and disease development using mechanical, graft, or insect vector inoculation methods. To reduce initial screening costs and time, we developed mechanical and graft inoculation methods suitable for tissue culture use. The in vitro methods were validated by comparing them with similar greenhouse screens using putative potato virus Y strain o (PVY degrees ) replicase-mediated resistant regenerants of the potato cultivar Atlantic. Five transgenic lines were tested, with similar results obtained from in vitro and greenhouse experiments. Two of the transgenic lines, A1 and A3, showed the greatest resistance to PVY degrees infection, as indicated by low enzyme-linked immunosorbent assay values and infection rates. In vitro mechanical inoculation methods were also used to infect wild-type tomato and tobacco plants with cucumber mosaic virus and potato virus Y. Potato plants were also infected with the phloem-restricted potato leafroll virus, a low-titer virus, using in vitro graft inoculation methods. These results suggest the potential usefulness of these simple, effective, and economical techniques for screening large numbers of putative virus-resistant plants.     

Investigating the effects of afforestation on soil erosion and sediment mobilisation in two small catchments in Southern Italy

Annual soil losses in southern Italy can exceed 100–150 t ha^− 1 year^− 1. Where erosion on agricultural land is particularly severe, land use change and afforestation are frequently seen as the most appropriate means of reducing erosion risk. However, the overall effectiveness of afforestation in reducing soil erosion remains uncertain, due to the poor development of the forest cover in some areas, leading to significant areas with sparse tree cover, and the erosional impact of forest harvesting, which commonly involves clearcutting. The study reported here addresses this uncertainty and focuses on two small catchments (W2 and W3) located in Calabria, southern Italy, for which measurements of suspended sediment yield are available. Both the catchments originally supported a rangeland vegetation cover and they were planted with eucalyptus trees in 1968. Currently, only catchment W3 supports a continuous forest cover. In catchment W2 the forest cover is discontinuous and there is a significant area of the catchment (ca. 20%) where the tree cover is sparse and the vegetation cover is dominated by natural grasses. Two additional erosion plots were established within catchment W2 in 1991, in order to explore the effect of the density of the tree cover on soil erosion. Information on the sediment yields from the two catchments and the plots for 10 storm events that occurred during the period December 2005–December 2006 and associated information on the ¹³⁷Cs and excess ²¹⁰Pb of the sediment, have been used to investigate the effectiveness of afforestation in reducing sediment mobilisation and net soil loss from the catchments involved. The results demonstrate that the areas of greatest soil loss are associated with the slopes where the tree cover is discontinuous, and that forest harvesting by clearcutting causes significant short-term increases in sediment mobilisation and sediment yield. These findings, which are consistent with previous work undertaken within the same area, emphasize the importance of vegetation cover density in influencing rates of soil loss in the study catchments. The study also provided a useful demonstration of the potential for using measurements of the ¹³⁷Cs and ²¹⁰Pb_ex content of sediment, in combination with more traditional sediment monitoring, to investigate sediment sources and to compare the sediment dynamics of catchments subjected to different land management practices.