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Detection and identification of Phytophthora species in southern Italy by RFLP and sequence analysis of PCR-amplified nuclear ribosomal DNA.
Full text linkIn four neighbouring regions of southern Italy, Basilicata, Campania, Apulia and Calabria, pepper and zucchini plants showing Phytophthora blight symptoms, tomato plants with either late blight or buckeye rot symptoms, plants of strawberry showing crown rot symptoms and declining clementine trees with root and fruit rot were examined for Phytophthora infections by means of polymerase chain reaction (PCR) assays, using primers directed to nuclear ribosomal DNA (rDNA) repeat sequences. All diseased plants and trees examined tested positive. The detected fungal-like organisms were differentiated and characterized on the basis of primer specificity as well as through extensive restriction fragment length polymorphism (RFLP) and sequence analysis of PCR-amplified rDNA. Phytophthora capsici was identified in diseased pepper and zucchini plants, P. infestans was identified in tomato with late blight symptoms whereas buckeye rot-affected tomatoes and diseased strawberry plants proved to be infected by P. nicotianae and P. cactorum, respectively. Declining clementine trees were infected with P. citrophthora and P. nicotianae in about the same proportion. Also, thirty-one pure culture-maintained isolates of Phytophthora which had previously been identified in southern Italy by traditional methods but were never examined molecularly, were examined by RFLP and sequence analysis of PCR-amplified nuclear rDNA. Among these, an isolate from gerbera which had previously been identified by traditional methods only at genus level, was assigned to P. tentaculata. For the remaining pure culture-maintained isolates examined, the molecular identification data obtained corresponded with those delineated by traditional methods. Most of the diseases examined were already known to occur in southern Italy but the pathogens were molecularly detected and fully characterized at nuclear rDNA repeat level only from other geographic areas, very often outside Italy. A new disease to southern Italy was the Phytophthora blight of zucchini. This is also the first report on the presence and molecular identification of P. tentaculata from Italy
European Stone Fruit Yellows (ESFY).
No full textSince the beginning of the twentieth century symptoms of apricot tree decline were observed in France and Italy: Morvan in 1977 named the disease associated with leptonecrosis (Goidanich, 1934) or with new sprouting in winter "apricot chlorotic leaf rolling" (ACLR). Only since the late 1970ies these symptoms were associated with phytoplasma infections, since electron or fluorescence microscopy (by DAPI-staining) allowed to detect phytoplasmas as single cells in sieve tubes (Fig. 1) and transmission experiments to other stone fruit and indicator plants were successfully carried out (Morvan, 1977; Goidanich et al., 1980; Giunchedi et al., 1982, Pastore et al., 1995).
European stone fruit yellows (acronym: ESFY) has been proposed as the common name for phytoplasma-related diseases in European stone fruits (Kison et al., 1997). Among others it includes the French ECA or ACLR, which is a quarantine organism of EPPO (OEPP/EPPO, 1986), included in the EPPO certification scheme for virus tested fruit trees (OEPP/EPPO, 1991/1992).The presence of ESFY disease has been reported in France, Spain, Italy, Greece, and in Hungary, Romania, Switzerland, Germany, former Yugoslavia, the UK and Austria (Nemeth, 1986; Morvan, 1977, Davies and Adams 2000, Laimer da Câmara Machado et al. 2001a) causing decline and death to apricot, Japanese plum, more rarely to peach (Llacer and Medina, 1988) and to almond, flowering cherry and European plum (Seemüller et al. 1998) http://www.boku.ac.at/iam/pbiotech/phytopath/v_esfy.html). An increasing presence of phytoplasma associated diseases such as leptonecrosis on Japanese plum (Prunus salicina) and chlorotic leaf roll on apricot (Prunus armeniaca) has been observed in commercial orchards in several European regions in the last twenty-five years (Giunchedi et al., 1978; Desvignes and Cornaggia, 1982; Dosba et al., 1991; Bertaccini et al., 1993; Laimer et al., 2001; Torres et al., 2004). Prunus rootstocks are also affected by this disease (Dosba et al. 1991, Jarausch et al. 1998). ESFY phytoplasmas have also been detected in wild Prunus species, e.g. Prunus spinosa and P. cerasifera (Carraro et al. 2002) and cherry (Prunus avium) (Paltrinieri et al., 2001). In recent years ESFY phytoplasma has been detected in other wild plants such as Rosa canina, Celtis australis and Fraxinus excelsior (Jarausch et al., 2001) as well as in grapevine in Hungary (Varga et al., 2000) and in Serbia (Duduk et al., 2004)
Phytoplasmas of apricot and Japanese plum.
No full textApricot (Prunus armeniaca L.) and Japanese plum (Prunus salicina L. spp) are the cultivated fruit trees species most sensible to phytoplasmas (Goidanich et al., 1980). The most commonly detected phytoplasma associated with these two species is the European stone fruit yellows (ESFY or 16SrX-B) phytoplasma, recently named “Candidatus Phytoplasma prunorum”, (Seemüller and Schneider, 2004); despite a 16r RNA gene sequence that shows more than 97,5 % similarity to those of other “Candidatus phytoplasma” mainly detected in fruit trees such as pear and apple, this phytoplasma is characterized by distinctive biological, phytopathological and genetic properties, therefore it was possible to describe it a as a separate Candidatus species (IRPCM, 2004).
Previous molecular studies on ESFY phytoplasma demonstrated similarity or identity of phytoplasmas inside the Apple proliferation 16S ribosomal group (16SrX). In particular the ESFY phytoplasmas in apricot, Japanese plum, European plum, and in flowering cherry and almond in European cultivations were shown to be indistinguishable at the molecular level (Seemüller et al., 1998). The chromosome map of a German ESFY strain was realized extracting phytoplasma DNA from Nicotiana glutinosa and/or from some tomato cultivars, after transmission of the pathogen to these species by dodder bridges (Marcone and Seemüller, 2001).
In other studies the virulence variability of ESFY phytoplasma strains was observed in field infected plants, mainly apricots, and the presence of avirulent or low virulent strains was proposed together with the idea of presence of non-specific phytoplasmas which could attenuate virulent ESFY phytoplasma strains (Seemüller, 1999).
Other phytoplasmas were reported to infect apricot or Japanese plum: in Spain a molecularly distinguishable 16S ribosomal subgroup of aster yellows (16SrI-F, Lee et al., 1998a) was transmitted to periwinkle from apricots, in Italy 16SrIII-B and/or 16SrX-B phytoplasmas were dodder transmitted to periwinkle from symptomatic plums (Carraro et al., 1992).
Recently, 16SrX-B phytoplasmas were identified from both symptomatic and asymptomatic Japanese plum, in areas where the presence of these phytoplasmas is very strong: testing 40 samples from 11 Japanese plum varieties, collected in June, from symptomatic plants, about 23% showed positive results in the first nested PCR reaction and 92% in the second, performed with 16SrX group specific primers 16Sr(X)F1/R1. When the same plants were retested in October, 39 out of the 40 samples were positive in direct PCR. However testing 57 asymptomatic Japanese plums, about 20% of the samples was positive to ESFY presence, moreover in other symptomatic samples phytoplasmas belonging to groups 16SrXII-A, 16SrI-B and 16rIII-B were identified (Paltrinieri et al., 2004)
Phytoplasmas of peach and cherry.
No full textRecent researches show the presence In Italy in cherry of phytoplasmas of 16SrIII group in some of the samples from plants recently imported from California (Paltrinieri et al., 2001), while in peach no clear relationship was detected among symptoms, peach variety and phytoplasma presence, but several phytoplasmas were detected in nectarine with yellows symptoms in Italy (Lee et al., 1995; Zhu et al., 1997; Paltrinieri et al., 2001). In the last two year 16SrV-B phytoplasmas were also detected and identified in severely declining peach and cherry in northern Italy (Paltrineri et al., 2005a), stolbur phytoplasmas (16SrXII-A) were also detected in plants with the same symptoms in Italy and in other part of the world (Paltrinieri et al., 2005b)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Detection and Characterization of Phytophthora Species Infecting Tomato in Southern Italy by DNA-Based Methods
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