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Use of genomics tools to study peach fruit postharvest physiology
No full textPeach and nectarine fruit ripen and deteriorate quickly and even at refrigerated temperature their storage life rarely exceeds 4-5 weeks making these fruit types interesting to study in terms of ripening and postharvest physiology. In this context, biochemical and one-to-one-at-a-time gene expression studies are now paralleled by large-scale analyses and genomics approaches using high throughput tools as the first peach microarray (μPEACH1.0) developed by the Italian Consortium for Genomics Studies in Prunus (ESTree Consortium). μPEACH1.0 has been used to study the transition from pre-climacteric to climacteric stage and to better characterize the role of ethylene in this fruit species. New genes and basic mechanisms involved in ethylene perception, and in the definition and evolution of quality traits as colour and flesh firmness have been identified. Differently from other fruit species (e.g., apple), 1-methylcyclopropene (1-MCP) has only a limited effect in delaying peach fruit ripening: in order to elucidate the mechanisms responsible for this behaviour, transcriptome analyses have been performed and genes showing differential hybridisations have been grouped according to their expression pattern following 1-MCP treatment. The comparison of transcript profiles in peaches at the transition from immature to mature stage, and following treatment with 1-MCP or exogenous ethylene allowed to identify gene ripening- and/or ethylene-regulated in this fruit species and comparatively assess the influence of ethylene on specific metabolic pathways
Factors affecting gene expression of Lipid Transfer Protein (LTP), the major allergen of peach fruit
No full textDifferent postharvest conditions modulate ripening and ethylene biosynthetic and signal transduction pathways in Stony Hard peaches.
No full textStony hard (SH) peaches are characterized, at ripening, by the maintenance of flesh firmness and the lack of ethylene production due to a reduced expression of Pp-ACS1. In a trial comparing melting flesh (MF, cv. ‘Summer Rich’) and SH (‘IFF331’ selection) fruit at two different postharvest temperatures (10 and 20 ◦C), unexpected behaviour was observed in SH peaches that displayed an increase in ethylene production and a decrease in flesh firmness when stored at 10 ◦C, a temperature regime basically ineffective in delaying ripening in MF fruit. This appeared to be the result of an induction of Pp-ACS1 transcription, making this genotype of particular interest for studying temperature stress physiology and ethylene-related ripening processes in peaches. Comparative expression analyses of genes involved in cell wall metabolism pointed out the presence of a negative (Pp-EG4), positive (Pp-endoPG) or no (one member of the PL family) relationship with ethylene at ripening. Results clearly showed that the last stage of firmness decrease (melting) only occurs in fruit producing ethylene and is associated with Pp-endoPG transcript accumulation. The expression of genes involved in ethylene biosynthesis and signalling pathways was evaluated using QRT-PCR. Pp-ACO1 appeared to be induced in SH kept at 10 ◦C but not at 20 ◦C. Transient increases in Pp-CTR1 and Pp-EIN2like gene expression have only been detected at the early stages of ripening in samples producing ethylene, indicating that a causal relationship might exist between ethylene and elements of its transduction pathway during peach fruit ripening
Transcriptome profiling of ripening nectarine (Prunus persica L. Batsch) fruit treated with 1-MCP
No full textA large-scale transcriptome analysis has been conducted using mPEACH1.0 microarray on nectarine (Prunus persica L. Batsch) fruit treated with 1-methylcyclopropene (1-MCP). 1-MCP maintained flesh firmness but did not block ethylene biosynthesis. Compared with samples at harvest, only nine genes appeared to be differentially expressed when fruit were sampled immediately after treatment, while a total of 90 targets were up- or down-regulated in untreated fruit. The effect of 1-MCP was confirmed by a direct comparison of transcript profiles in treated and untreated fruit after 24 h of incubation with 106 targets differentially expressed. About 30% of these targets correspond to genes involved in primary metabolism and response processes related to ethylene, auxin, and other hormones. In treated fruit, altered transcript accumulation was detected for some genes with a role in ripening-related events such as softening, colour development, and sugar metabolism. A rapid decrease in flesh firmness and an increase in ethylene production were observed in treated fruit maintained for 48 h in air at 20 oC after the end of the incubation period. Microarray comparison of this sample with untreated fruit 24 h after harvest revealed that about 45% of the genes affected by 1-MCP at the end of the incubation period changed their expression during the following 48 h in air. Among these genes, an ethylene receptor (ETR2) and three ethylene responsive factors (ERF) were present, together with other transcription factors and ethylene-dependent genes involved in quality parameter changes
Utilizzo di un microarray (microPEACH1.0) per lo studio del trascrittoma durante la maturazione della pesca
No full textTranscriptome profiling of ripening nectarine (Prunus persica L. Batsch) fruit treated with 1-MCP
Full text linkA large-scale transcriptome analysis has been conducted using μPEACH1.0 microarray on nectarine (Prunus persica L. Batsch) fruit treated with 1-methylcyclopropene (1-MCP). 1-MCP maintained flesh firmness but did not block ethylene biosynthesis. Compared with samples at harvest, only nine genes appeared to be differentially expressed when fruit were sampled immediately after treatment, while a total of 90 targets were up- or down-regulated in untreated fruit. The effect of 1-MCP was confirmed by a direct comparison of transcript profiles in treated and untreated fruit after 24 h of incubation with 106 targets differentially expressed. About 30% of these targets correspond to genes involved in primary metabolism and response processes related to ethylene, auxin, and other hormones. In treated fruit, altered transcript accumulation was detected for some genes with a role in ripening-related events such as softening, colour development, and sugar metabolism. A rapid decrease in flesh firmness and an increase in ethylene production were observed in treated fruit maintained for 48 h in air at 20 °C after the end of the incubation period. Microarray comparison of this sample with untreated fruit 24 h after harvest revealed that about 45% of the genes affected by 1-MCP at the end of the incubation period changed their expression during the following 48 h in air. Among these genes, an ethylene receptor (ETR2) and three ethylene-responsive factors (ERF) were present, together with other transcription factors and ethylene-dependent genes involved in quality parameter changes
Expression and tissue-specific localization of nitrate-responsive miRNAs in roots of maize seedlings
No full textAbstract
Nitrogen availability seriously affects crops productivity and environment. The knowledge of post-transcriptional regulation of plant response to nutrients is important to improve nitrogen use efficiency of crop. This research was aimed at understanding the role of miRNAs in the molecular control of plant response to nitrate.
A maize miRNAs-microarray platform was used to discover previously unknown nitrate-responsive miRNAs. Six mature miRNA were identified and their expression profiles were deeply studied by qPCR and in situ hybridization (ISH). To this aim a novel optimized protocol was set up for the use of DIG labelled ZNA (Zip Nucleic Acid)-modified oligonucleotides as probes for ISH. Significant differences in miRNAs’ transcripts accumulation were evidenced between nitrate-supplied and nitrate-depleted roots. Real time PCR analyses and in situ detection of miRNA, confirmed the arrays data and allowed us to evidence distinct miRNAs spatio-temporal expression patterns in maize roots. Our results suggest that a prolonged nitrate depletion may induce post-transcriptionally the expression of target genes by repressing the transcription of specific miRNAs. In particular, the repression of the transcription of miR528a/b, miR528a*/b*, miR169i/j/k, miR169i*/j*/k*, miR166j/k/n and miR408/b upon nitrate shortage could represent a crucial step integrating nitrate signals into developmental changes in maize roots
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
Molecular and genetic aspects of ripening and qualitative traits of peach and nectarine fruits
No full textExpressed Sequence Tags (ESTs) and cDNA-AFLP analysis have been used to study gene expression during peach fruit ripening. An EST repertoire (1007 sequences) has been constructed using transcripts in nectarine fruit cv. ‘Fantasia’ at climacteric stage. The EST repertoire was reduced to 696 unigenes: in these 579 (83%) were singletons. EST analysis confirmed that in peach ripe fruit, genes involved in ethylene biosynthesis and cell wall metabolism are highly represented. Three transcription factors (TFs) homologous to SEPALLATA3, atb2, bHLH61 belonging to MADS, bZIP and bHLH families, respectively, have been identified. The abundance of the related transcripts suggests that these TFs play a regulatory role of ripening, as reporter in other fruits species. The EST repertoire has been included in a sequence database assembled by the Italian Consortium for Prunus spp genomic study to generate the first peach fruit microarray (μPEACH 1.0). EST analysis has been integrated with cDNA-AFLP to study a selection of the nectarine cv. ‘Fantasia’, named slr, characterized by a block of ripening. Data pointed out that the slr fruit phenotype might be due to disturbance in the onset of senescence
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