1,721,016 research outputs found
DIFFERENTIAL MODULATION OF PLANT AND FUNGAL PHOSPHATE TRANSPORTERS AND EXPRESSION OF MYCELIAL TRAITS IN DIVERSE MYCORRHIZAL MAIZE INBRED LINES
Get PDFCurrent food crop production systems are heavily dependent on the use of
chemical fertilizers, of which those containing phosphorus (P), essential
for plant growth and development, represent a non-renewable mineral
resource whose reserves are estimated to decline within 100-200 years. The
microbiota associated with plant roots, mainly represented by arbuscular
mycorrhizal fungi (AMF) can be exploited for reducing external P input into
agro-ecosystems. In this study, plant and fungal variables involved in P
acquisition were investigated in four maize inbred lines (Oh40B, Mo17, Oh43
and B73), differing for mycorrhizal responsiveness and low-P tolerance,
when inoculated with the symbiont Rhizoglomus irregulare. The expression
patterns of genes encoding phosphate transporters (PTs) in extraradical and
intraradical mycelium (ERM and IRM) and in maize roots were assessed along
with plant growth responses, P uptake and ERM extent and structure. The
four maize lines differed in expression levels of PT genes in both plant
and fungal tissues, in ERM phenotypic traits and plant performance.
Expression of PT genes in roots and ERM of the low-P tolerant maize line
Mo17 was higher than that detected in the low-P susceptible line B73, which
revealed larger ERM hyphal densities and interconnectedness. Significant
correlations were found between ERM structural traits, and both expression
levels of PT genes and mycorrhizal host benefit data.
Further studies aimed at improving our knowledge of the genetic mechanisms
regulating the functioning of AMF symbiosis may lead to the development of
new strategies of targeted molecular breeding to obtain more sustainable
low-P tolerant crops
THE CRISPR/CAS9 EDITING OF A WRKY GENE AND THE OVEREXPRESSION OF A LIPOXYGENASE GENE FOR IMPROVING PATHOGEN RESISTANCE IN MAIZE
Get PDFFusarium verticillioides (Fv) is a major cereal pathogen causing stalk rot
and ear rot in maize, negatively affecting crop productivity, and
compromising food safety by producing the secondary metabolites fumonisins.
Several studies were conducted to identify maize genes associated with host
plant resistance to Fv infection and fumonisin accumulation. The maize WRKY
transcription factors and the lipoxygenases (ZmLOXs) are well recognized as
important players in plant defense against pathogens, and it is known that
the host-pathogen lipid cross-talk influences the pathogenesis. In this
regard, previous RNA-seq experiments reported the enhanced expression of
ZmLOX genes in maize resistant genotypes and GWAS resulted in one SNP
significantly associated with ZmWRKY125.
The Clustered Regularly Interspaced Short Palindromic Repeat/associated
Cas9 (CRISPR/Cas9) editing of ZmWRKY125 and the transgenic overexpression
of ZmLOX4 genes were carried out to investigate the possible implication of
these two genes in the resistance mechanisms against Fv. Before cloning
experiments, protein domain conservation and different splicing products
have been analyzed comparing homologues and orthologues for both genes.
As regards ZmWRKY125, the CRISPR cloning was based on a double cloning
using two different guides (sgRNA) for one gene target. Agrobacterium
tumefaciens mediated transformation was used for introducing the construct
under the maize promoter ZmpUBI in the binary vector p1609 in maize A188
line. Mutants from three different transformation events were obtained. For
each event, T2 plants will be genotyped to find homozygous for the mutation
that in turn will be phenotyped for Fv resistance and fumonisin content.
As regards ZmLOX4, the gene was cloned under an overexpressed promoter
involved in kernel development in the vector L1781, and the same
transformation conditions adopted for the CRISPR/Cas9 editing of ZmWRKY125
were used. Mutants from two different transformation events were obtained.
For each event, T2 plants were genotyped in order to find homozygous for
the mutation. Homozygous plants will be further evaluated for Fv
resistance, fumonisin accumulation, oxylipin content as well as for the
expression analysis of the main genes involved in the jasmonic acid pathway
TRANSCRIPTIONAL ANALYSIS OF EIGHT MAGIC MAIZE PARENTAL LINES INFECTED WITH FUSARIUM VERTICILLIOIDES
Get PDFMaize (Zea mays L.) is among the most important crops worldwide for food,
feed, biofuels, and industrial applications. Its cultivation faces
significant constraints due to Fusarium species that affect the quality and
quantity of maize products. Among these, Fusarium verticillioides is
responsible for severe diseases including seedling blights, stalk rot, and
ear rot. The impact of the fungus is worsened by the fact that chemical and
agronomic measures used to control Fusarium infection are often
inefficient. Hence, genetic resistance is considered the most reliable
resource to reduce damages caused by F. verticillioides. This study aims to
elucidate the genetic basis of resistance to this fungus in maize. Young
seedlings of eight divergent maize lines, founder of the MAGIC population,
were artificially inoculated with a F. verticillioides strain using the
rolled towel assay method. Total RNA was extracted from both control and
treated samples after 72 hours of artificial inoculation and underwent
paired-end sequenced with Illumina technology. Here we report the use this
large transcriptomic dataset to identify the early transcriptional changes
and the differentially expressed genes (DEGs) involved in fungal infection.
The analysis identified several hundred DEGs, whose functions were explored
through Gene Ontology enrichment analysis. A co-expression network analysis
further refined the set of genes with potential implications in disease
response. The results identify a limited set of genes that might play an
important roles in maize resistance to F. verticillioides providing new
insights into the molecular resistance mechanisms against the pathogen
Expression analysis and biochemical studies of defense-related genes in the pathosystem Fusarium verticilliodes-maize
No full textFusarium verticillioides and aspergillus flavus co-occurrence influences plant and fungal transcriptional profiles in maize kernels and in vitro
Get PDFClimate change will increase the co-occurrence of Fusarium verticillioides and Aspergillus flavus, along with their mycotoxins, in European maize. In this study, the expression profiles of two pathogenesis-related (PR) genes and four mycotoxin biosynthetic genes, FUM1 and FUM13, fumonisin pathway, and aflR and aflD, aflatoxin pathway, as well as mycotoxin production, were examined in kernels and in artificial medium after a single inoculation with F. verticillioides or A. flavus or with the two fungi in combination. Different temperature regimes (20, 25 and 30◦ C) over a time-course of 21 days were also considered. In maize kernels, PR genes showed the strongest induction at 25◦ C in the earlier days post inoculation (dpi)with both fungi inoculated singularly. A similar behaviour was maintained with fungi co-occurrence, but with enhanced defence response at 9 dpi under 20◦ C. Regarding FUM genes, in the kernels inoculated with F. verticillioides the maximal transcript levels occurred at 6 dpi at 25◦ C. At this temperature regime, expression values decreased with the co-occurrence of A. flavus, where the highest gene induction was detected at 20◦ C. Similar results were observed in fungi grown in vitro, whilst A. flavus presence determined lower levels of expression along the entire time-course. As concerns afl genes, considering both A. flavus alone and in combination, the most elevated transcript accumulation occurred at 30◦ C during all time-course both in infected kernels and in fungi grown in vitro. Regarding mycotoxin production, no significant differences were found among temperatures for kernel contamination, whereas in vitro the highest production was registered at 25◦ C for aflatoxin B1 and at 20◦ C for fumonisins in the case of single inoculation. In fungal co-occurrence, both mycotoxins resulted reduced at all the temperatures considered compared to the amount produced with single inoculation
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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