1,720,972 research outputs found
Description of durum wheat linkage map and comparative sequence analysis of wheat mapped DArT markers with rice and Brachypodium genomes
No full textBackground: The importance of wheat to the world economy, together with progresses in high-throughput next-generation DNA sequencing, have accelerated initiatives of genetic research for wheat improvement. The availability of high density linkage maps is crucial to identify genotype-phenotype associations, but also for anchoring BAC contigs to genetic maps, a strategy followed for sequencing the wheat genome.Results: Here we report a genetic linkage map in a durum wheat segregating population and the study of mapped DArT markers. The linkage map consists of 126 gSSR, 31 EST-SSR and 351 DArT markers distributed in 24 linkage groups for a total length of 1,272 cM. Through bioinformatic approaches we have analysed 327 DArT clones to reveal their redundancy, syntenic and functional aspects. The DNA sequences of 174 DArT markers were assembled into a non-redundant set of 60 marker clusters. This explained the generation of clusters in very small chromosome regions across genomes. Of these DArT markers, 61 showed highly significant (Expectation < E-10) BLAST similarity to gene sequences in public databases of model species such as Brachypodium and rice. Based on sequence alignments, the analysis revealed a mosaic gene conservation, with 54 and 72 genes present in rice and Brachypodium species, respectively.Conclusions: In the present manuscript we provide a detailed DArT markers characterization and the basis for future efforts in durum wheat map comparing. © 2013 Colasuonno et al.; licensee BioMed Central Lt
Regulation and Evolution of NLR Genes: A Close Interconnection for Plant Immunity
No full textNLR (NOD-like receptor) genes belong to one of the largest gene families in plants.
Their role in plants’ resistance to pathogens has been clearly described for many members of this
gene family, and dysregulation or overexpression of some of these genes has been shown to induce
an autoimmunity state that strongly affects plant growth and yield. For this reason, these genes
have to be tightly regulated in their expression and activity, and several regulatory mechanisms are
described here that tune their gene expression and protein levels. This gene family is subjected to
rapid evolution, and to maintain diversity at NLRs, a plethora of genetic mechanisms have been
identified as sources of variation. Interestingly, regulation of gene expression and evolution of this
gene family are two strictly interconnected aspects. Indeed, some examples have been reported in
which mechanisms of gene expression regulation have roles in promotion of the evolution of this
gene family. Moreover, co-evolution of the NLR gene family and other gene families devoted to their
control has been recently demonstrated, as in the case of miRNAs
Molecular mapping of stomatal-conductance-related traits in durum wheat (Triticum turgidum ssp.durum Desf.)
No full text"The most promising traits identified in wheat to raise yield potential via an increase in biomass accumulation are stomatal conductance and stomatal-conductance-related traits, such as carbon isotope discrimination (CID) and photosynthetic rate. The evaluation of the extent of genetic variation and the mapping of chromosomal regions controlling these traits are essential for the development of effective breeding strategies in durum wheat. A population of 161 F2-derived, F8-F9 recombinant inbred lines obtained from a cross between durum wheat (Triticum turgidum ssp. durum Desf.) cultivars Ofanto and Cappelli was phenotyped for heading date, plant height, leaf porosity, CID and chlorophyll concentration (estimated through the SPAD index) for 2007\/2008 and 2008\/2009 seasons, at Ottava, Sardinia (Italy) under irrigated conditions. The genotype mean heritability for leaf porosity, CID and chlorophyll concentration was moderate in size. Six quantitative trait loci were detected for leaf porosity, four for chlorophyll concentration, but only one for CID, because of the small variation expressed in the population for this trait under these experimental conditions. The quantitative trait loci for leaf porosity located on chromosome 3B appear to be more stable with respect to the others, and different microsatellite markers are positioned within the interval of the quantitative trait loci, or in their vicinity, that represent useful tools in programmes for selection assisted by molecular markers.
Genetic variation for the duration of pre-anthesis development in durum wheat and its interaction with vernalization treatment and photoperiod
No full textA recombinant inbred durum wheat population was grown under three contrasting regimes: long days following vernalization (LDV), long days without vernalization (LD), and short days following vernalization (SDV). The length of several pre-anthesis stages and the number of leaves and the phyllochron were measured. Different groups of genes were involved in determining the phenology in the three treatments, as demonstrated by a quantitative trait locus (QTL) analysis. The length of the period required to reach the terminal spikelet stage was correlated with the time to anthesis only in the case of LDV- and LD-grown plants where the timing of anthesis depended on the final leaf number. However, for SDV-grown plants, anthesis date was more dependent on the length of the period between the terminal spikelet stage and anthesis and was independent of leaf number. The involvement of the phyllochron in determining the duration of pre-anthesis development was also treatment-dependent. QTL mapping of the various flowering time associated traits uncovered some novel loci (such as those associated with the phyllochron), in addition to confirming the presence of several well-established loci
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
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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