1,720,961 research outputs found
Reduced gibberellin biosynthesis and response in fruits of the auxin insensitive diageotropica tomato mutant
No full textAuxin has a central role in determining tomato fruit growth and development, and most of its action is mediated by gibberellins (GAs). The diageotropica (dgt) mutant of tomato exhibits many physiological responses that are related to a defective auxin sensitivity. In this paper we investigated the effects of the dgt mutation on tomato gibberellin biosynthesis regulation during fruit-set and early growth of pollinated fruits. In spite of an initial accumulation of active GAs in dgt ovaries, their content is significantly reduced at later stages. Indeed, at the beginning of rapid fruit growth, dgt fruits display a lower amount of GA(1) and its direct catabolite GA(8). Consistently, transcripts of GA 20-oxidase genes (GA20ox1, GA20ox2, GA20ox3) are low in the mutant. Moreover, low expression of genes encoding GA catabolism enzymes (GA 2 beta-hydroxylases) does not lead to an increase in the amount of active GAs, supporting the hypothesis that GA 20-oxidase genes downregulation might bottleneck the synthesis of active GAs in dgt. Interestingly, exogenous GA(3) application has little effect on dgt ovaries. GA(3)-treated fruits of the mutant are smaller than those of its wild type as a result of fewer and smaller pericarp cells. Consistently, GA(3) treatment in the dgt ovaries produces negligible effects on cell endoreduplication revealed by a lower nuclear DNA content in pericarp and locular tissue cells. The lack of DELLA-mediated constraint on GA signal in the double mutant dgt pro did not cause an increase in size and weight in pollinated fruits, suggesting that GA signalling is unable to overcome the inhibition of growth caused by the dgt mutation
AUXIN AND GIBBERELLINS INTERACTION DURING FRUIT SET IN TWO TOMATO AUXIN MUTANTS: GIBBERELLIN BIOSYNTHESIS GENE EXPRESSION AND NUCLEAR DNA CONTENT
No full textExtraction and determination of ascorbate and dehydroascorbate from apoplastic fluid of stem of rooted and non-rooted cuttings in relation to the rhizogenesis.
No full textStarting from semihardwood shoots of peach rootstocks (Prunus cerasifera E.) cv. Mr.S.2/5, plum rootstocks (Prunus cerasifera × P. salicina) × (P. cerasifera × P. persica) cv. Ishtarà and olive tree (Olea europaea L.) cv. Frantoio, cuttings were collected and treated with 0 mgL-1 and 2500 mgL-1 of indolebutyric acid (IBA) by immersion the base of the cuttings. After 60 days of planting, the cultivars Mr.S. 2/5, Ishtarà and Frantoio presented a significative difference with relation to the rooting induction by application of the indolebutyric acid (27.5, 47.5 and 41.25 %, respectively), inducing a higher number of roots per cutting without at the same time significantly increasing the length of the roots themselves. The levels of ascorbate and dehydroascorbate in the rooted and non-rooted cuttings of the three cultivars were determined. These parameters varied in function of the consistency of the cuttings from each species, but showed a positive correlation between the increase of the rooting and the increase of the ascorbate
in the reduced form
Role of gibberellins in two tomato auxin signalling mutants during the early stages of fruit development
No full text
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
Tomato fruit development in the auxin-resistant dgt mutant is induced by pollination but not by auxin treatment
No full textIn tomato (Solanum lycopersicum Mill.), auxin is believed to play a pivotal role in controlling fruit-set and early ovary growth. In this paper we investigated the effect of the reduced auxin sensitivity exhibited by the diageotropica (dgt) tomato mutant on ovary growth during early stage of fruit development. Here we show that in hand-pollinated ovaries fruit-set was not affected by the dgt lesion while fruit growth was reduced. This reduction was associated with a smaller cell size of mesocarp cells, with a lower mean C values and with a lower gene expression of the expansin gene LeExp2. When a synthetic auxin (4-CPA, chlorophenoxyacetic acid) was applied to the flowers of wild type plants, parthenocarpic ovary growth was induced. On the contrary, auxin application to the flowers of dgt plants failed to induce parthenocarpy. Hand-pollinated ovaries of dgt contained higher levels of IAA compared to wild type and this was not associated with high transcript levels of genes encoding a key regulatory enzyme of IAA biosynthesis (ToFZYs) but with lower expression levels of GH3, a gene involved in the conjugation of IAA to amino acids. The expression of diverse Aux/IAA genes and SAUR (small auxin up-regulated RNA) was also altered in the dgt ovaries. The dgt lesion does not seem to affect specific Aux/IAA genes in terms of transcript occurrence but rather in terms of relative levels of expression. Transcript levels of Aux/IAA genes were up regulated in auxin-treated ovaries of wild-type but not in dgt
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
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