1,721,000 research outputs found
Venturia inaequalis resistance in apple
No full textApple scab caused by Venturia inaequalis has evoked the interest for quite different reasons of scientists, agronomists, producers and consumers since over a century. Consumers select spotless apples, producers want to avoid damage, agronomists are asked to develop and implement control measures mostly based on fungicides, scientists are challenged to find cheaper and less questioned control measures. Under these premises a high number of publications have appeared dealing with almost all aspects of the interaction V. inaequalis-Malus. This review considers the advances of the past 10 years due to new genetic tools. It tries to reevaluate and value earlier works. The complex genetic of scab resistance in Malus is viewed in the context of single resistance genes, QTLs and functional interactions at molecular level. Consequences for breeding and for the creation of genetically modified apples are discussed
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
Resistance gene analogues of HcrVf2 in apple
No full textThe HcrVf2 gene, isolated from the Vf locus, is the first apple scab resistance gene cloned from apple. During the cloning of HcrVf2 it was found that the R-gene belongs to a cluster of four genes and that others HcrVf2-like genes are present in (unknown) loci of the apple genome. The genomic library of the apple cv. 'Florina' (Vf) used to identify HcrVf2 has been screened by hybridization using the whole HcrVf2 sequence as probe to identify all the BAC clones carrying sequences homologous to this gene. Eleven BAC clones not belonging to the contigs assembled to clone HcrVf2 were found. The relative overlapping of the 11 BACs was studied, an SSRs marker was developed from each contig and the SSRs were mapped in the cross 'Fiesta' × 'Discovery'. The analysis of six BAC clones was sufficient to identify all the HcrVf2-like sequences present on these 11 BAC clones. In addition to these BACs, other 7 clones, belonging to the contigs assembled to clone HcrVf2 and known to carrying (unstudied) HcrVf-like sequences, were also investigated. All the 13 BAC clones have been subcloned, subclones carrying HcrVf-like sequences identified, sequenced and for each HcrVf-like sequence a consensus sequence has been generated. Of these 13 BAC clones, 22 sequences showing homologies to HcrVf2 were retrieved. Nine sequences (including HcrVf4) encoded ORFs showing all seven domains found in HcrVf2, and six of them have been shown to be expressed constitutively in young scab uninfected apple leaves of 'Florina' by RT-PCR
Advances in marker-assisted selection for scab resistance in apple and cloning of the Vf gene
No full textThis paper reviews molecular studies conducted on scab resistance in apple worldwide in the last decade. A detailed description of the DCA-BO and ETH-Zurich's activity, from the identification of molecular markers tightly linked to the Vf gene, their possible use in marker-assisted selection, advances of the map-based gene cloning strategy and the genetic trasformation of susceptible cultivars with the BIBAC technology to identify the resistance gene, is also surveyed
Apple contains receptor-like genes homologous to the Cladosporium fulvum resistance gene family of tomato with a cluster of genes cosegregating with Vf apple scab resistance
No full textScab caused by the fungal pathogen Venturia inaequalis is the most common disease of cultivated apple (Malus x domestica Borkh.). Monogenic resistance against scab is found in some small-fruited wild Malus species and has been used in apple breeding for scab resistance. Vf resistance of Malus floribunda 821 is the most widely used scab resistance source. Because breeding a high-quality cultivar in perennial fruit trees takes dozens of years, cloning disease resistance genes and using them in the transformation of high-quality apple varieties would be advantageous. We report the identification of a cluster of receptor-like genes with homology to the Cladosporium fulvum (Cf) resistance gene family of tomato on bacterial artificial chromosome clones derived from the Vf scab resistance locus. Three members of the cluster were sequenced completely. Similar to the Cf gene family of tomato, the deduced amino acid sequences coded by these genes contain an extracellular leucine-rich repeat domain and a transmembrane domain. The transcription of three members of the cluster was determined by reverse transcription-polymerase chain reaction to be constitutive, and the transcription and translation start of one member was verified by 5′ rapid amplification of cDNA ends. We discuss the parallels between Cf resistance of tomato and Vf resistance of apple and the possibility that one of the members of the gene cluster is the Vf gene. Cf homologs from other regions of the apple genome also were identified and are likely to present other scab resistance genes
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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