1,720,978 research outputs found
Root traits and yield in sugar beet: identification of AFLP markers associated with root elongation rate
No full textMorpho-physiological and molecular analysis were conducted to identify useful root indexes of sugar beet nutrient uptake capacity and productivity. Root architectural parameters, root elongation rate, sulfate uptake rate and glucose and fructose content in the root apex, traits involved in the plant response to sulfate stress, were evaluated in 18 sugar beet genotypes characterized by different root yield. Morpho-physiological traits, determined on 11-day-old seedlings grown in hydroponics under sulfate deprivation, showed variations from 59 to 197% and were significantly correlated (P<0.01) with root yield. Under field conditions, the highest root yield genotype (L18), which has the highest root phenotypic values following sulfate shortage, also showed the greatest root length density and leaf relative water content, with respect to the lowest root yield genotype (L01). Bulk segregant analysis based on AFLP analysis, done on a segregating progeny obtained from the cross between the two lines L01 9 L18, allowed the identification of two AFLP markers associated to the root elongation rate parameter that showed the highest variation among all the analyzed root traits. The genetic diversity of root adaptive traits and the use of marker-assisted selection aimed at increasing sugar yield under water and nutrient stress in sugar beet breeding programmes are discussed
Apparato radicale e competitività della barbabietola da zucchero verso le malerbe
No full textIl controllo delle specie infestanti, senza l’impiego di erbicidi di sintesi, è uno dei principali limiti alla coltivazione della barbabietola da zucchero in una agricoltura low-input e/o biologica. Lo scopo del lavoro è stato quello di identificare, in due linee di barbabietola ad alta e bassa produttività, i complessi genici legati a tratti morfofunzionali dell’apparato radicale (lunghezza radicale totale, superficie radicale e numero di apici) utili indici della capacità competitiva della barbabietola nei confronti delle malerbe. Questi caratteri sono stati valutati in plantule di sedici giorni allevate in soluzione idroponica, mentre in campo sono stati esaminati lo sviluppo radicale e la densità delle infestanti. La linea caratterizzata da una maggiore lunghezza, superficie radicale, numero di apici e densità radicale lungo il profilo del terreno ha evidenziato una superiore abilità competitiva contro le malerbe (minore densità di infestanti) e una maggiore produttività anche in loro presenza. Sulla progenie F1, ottenuta dall’incrocio tra le due linee caratterizzate da maggiore e minore produttività e che hanno mostrato rispettivamente alto e basso accrescimento radicale, è stata svolta l’analisi QTL al fine di identificare marcatori genetici associati alla lunghezza radicale totale. L’analisi ha evidenziato l’esistenza di quattro geni maggiori responsabili della lunghezza radicale. I marcatori morfofunzionali e molecolari identificati nel presente lavoro potranno consentire di selezionare linee di barbabietola che richiedono un minore impiego di mezzi tecnici per il controllo delle malerbe e, pertanto, maggiormente adattabili a sistemi agricoli eco-compatibili o basati su metodi biologici
Molecular and morphological differentiation among sea, ruderal and cultivated beets
No full textKnowledge of genetic diversity and relationships among Beta vulgaris genetic resources is essential for their conservation and development of breeding populations. In this study, we compared patterns of genetic variability and quantitative morphological data between a sea and a ruderal beet populations, collected on near sites of the Tyrrhenian coast of Italy, and a sugar beet variety. Eight amplified fragment length polymorphism (AFLP) primer-pairs were used for the genetic analysis whereas five traits of the root apparatus were evaluated for the morphological analysis in sixteen-day-old seedlings grown in hydroponics. Clustering analysis based on AFLP markers and root morphological data showed similar patterns of differentiation, in which sea, ruderal and cultivated beets appeared to be genetically distinct groups. A higher level of genetic variability was detected in the sea beet population, which may be due both to the limited gene flow between populations and the highly variable patterns of selection that occur in ecological niches, with respect than the genetic variability observed in the ruderal and cultivated beets. The results of this study revealed the extent of genetic diversity present within undomesticated beet populations that could be valuable in sugar beet improvement
Molecular and morpho-physiological characterization of sea, ruderal and cultivated beets
No full textBeta vulgaris genetic resources are essential for broadening genetic base of sugar beet and developing cultivars adapted to adverse environmental conditions. Wild beets (sea beets, B. vulgaris spp. maritima and their naturalized introgressions with cultivated beets known as ruderal beets) harbor substantial genetic diversity that could be useful for beet improvement. Here, we compared molecular and morpho-physiological traits of wild beets collected on the Adriatic coast of Italy with sugar beet using eight primer-pairs amplifying 194 polymorphic fragments and four root traits (glucose and fructose content in the root tip, root elongation rate, number of the of root tips, total root length and its distribution among diameters ranges). Genetic diversity was higher in the sea beet accession, which may be due to the highly variable selection pressures that occur in heterogeneous ecological niches, compared with the ruderal and cultivated beets. Sea and sugar beet accessions showed contrasting root patterns in response to sulfate deprivation: sugar beet showed an increase of reducing sugars in the root tips and higher root elongation rate, and the sea beet accession showed an increase in root tip number, total root length and fine root length (average diameter\0.5 mm). The ruderal beet showed intermediary responses to sea and sugar beet accessions. AFLP and morpho-physiological cluster analyzes showed sea, ruderal and cultivated beets to be genetically distinct groups. The results of this study indicate variability in response to sulfate deprivation is present in undomesticated beets that could be deployed for sugar beet improvement
Single nucleotide polymorphism markers linked to root elongation rate in sugar beet
Full text linkThe aim of this study was to identify single nucleotide polymorphism (SNP) markers genetically linked to root elongation rate (RER) in sugar beet (Beta vulgaris L.). A population of 244 F3 individuals, obtained from the cross between lines L01 (low RER) and L18 (high RER), was phenotyped by measuring RER of 11-d-old seedlings grown in hydroponic culture. Two DNA bulks of 50 F3 individuals with extremes phenotypes were used for bulk segregant analysis (BSA) by restriction-associated DNA (RAD) sequencing. A total of 20 376 SNP were identified. SNPs were filtered to reduce the number of false positive and mapped on candidate chromosomal regions the B. vulgaris reference genome. A total of SNPs were selected one of which, SNP10139, was strongly linked (P < 0.01) to RER. The pattern of association between SNP10139 genotype and RER was also evaluated on a breeding line panel comprising 40 low and 40 high RER individuals with different allele frequencies between groups (P < 0.01). The SNP10139 sequence was mapped the B. vulgaris peptide transporter (PTR) gene, a carrier that influences root elongation in Arabidopsis thaliana. Our results suggest that SNP10139 influences RER in sugar beet and sequence information can be used in marker- assisted selection programs
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
- …
