A method to analyze time expression profiles demonstrated in a database of chili pepper fruit development.
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ABSTRACT:
SUBMITTER: Escoto-Sandoval C
PROVIDER: S-EPMC8222228 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background The set of all mRNA molecules present in a cell constitute the transcriptome. The transcriptome varies depending on cell type as well as in response to internal and external stimuli during development. Chili pepper is an economically and culturally important horticultural crop as well as a good model for the study of secondary metabolism during fruit development. Here we present a study of the changes that occur in the transcriptome of chili pepper fruit during development and ripening. Results RNA-Seq was used to obtain transcriptomes of whole Serrano-type chili pepper fruits (Capsicum annuum L.; 'Tampiqueno 74') collected at 10, 20, 40 and 60 days after anthesis (DAA). 15,550,468 Illumina MiSeq reads were assembled de novo into 34,066 chili genes. We classified the expression patterns of individual genes as well as genes grouped into Biological Process ontologies and Metabolic Pathway categories using statistical criteria. For the analyses of gene groups we added the weighted expression of individual genes. This method was effective in interpreting general patterns of expression changes and increased the statistical power of the analyses. Subsets of genes were expressed only at a single time point sampled (1,278, 1,596, 1,519 and 1,583 genes at 10, 20, 40 and 60 DAA, respectively). We also estimated the variation in diversity and specialization of the transcriptome during chili pepper development. Approximately 17% of genes exhibited a significant change of expression in at least one of the intervals sampled. In contrast, significant differences in approximately 63% of the Biological Processes and 80% of the Metabolic Pathways studied were detected in at least one interval. Confirming previous reports, genes related to capsaicinoid and ascorbic acid biosynthesis were significantly upregulated at 20 DAA while those related to carotenoid biosynthesis were highly expressed in the last period of fruit maturation (40-60 DAA). Our RNA-Seq data was validated by examining the expression of nine genes involved in carotenoid biosynthesis by qRT-PCR. Conclusions In general, more profound changes in the chili fruit transcriptome were observed in the intervals between 10 to 20 and 40 to 60 DAA. The last interval, between 40 to 60 DAA, included 49% of all significant changes detected, and was characterized predominantly by a global decrease in gene expression. This period signals the end of maturation and the beginning of senescence of chili pepper fruit. The transcriptome at 60 DAA was the most specialized and least diverse of the four states sampled.
2014-02-21 | GSE54123 | GEO
Project description:BACKGROUND: The set of all mRNA molecules present in a cell constitute the transcriptome. The transcriptome varies depending on cell type as well as in response to internal and external stimuli during development. Here we present a study of the changes that occur in the transcriptome of chili pepper fruit during development and ripening. RESULTS: RNA-Seq was used to obtain transcriptomes of whole Serrano-type chili pepper fruits (Capsicum annuum L.; 'Tampiqueño 74') collected at 10, 20, 40 and 60 days after anthesis (DAA). 15,550,468 Illumina MiSeq reads were assembled de novo into 34,066 chili genes. We classified the expression patterns of individual genes as well as genes grouped into Biological Process ontologies and Metabolic Pathway categories using statistical criteria. For the analyses of gene groups we added the weighted expression of individual genes. This method was effective in interpreting general patterns of expression changes and increased the statistical power of the analyses. We also estimated the variation in diversity and specialization of the transcriptome during chili pepper development. Approximately 17% of genes exhibited a significant change of expression in at least one of the intervals sampled. In contrast, significant differences in approximately 63% of the Biological Processes and 80% of the Metabolic Pathways studied were detected in at least one interval. Confirming previous reports, genes related to capsaicinoid and ascorbic acid biosynthesis were significantly upregulated at 20 DAA while those related to carotenoid biosynthesis were highly expressed in the last period of fruit maturation (40-60 DAA). Our RNA-Seq data was validated by examining the expression of nine genes involved in carotenoid biosynthesis by qRT-PCR. CONCLUSIONS: In general, more profound changes in the chili fruit transcriptome were observed in the intervals between 10 to 20 and 40 to 60 DAA. The last interval, between 40 to 60 DAA, included 49% of all significant changes detected, and was characterized predominantly by a global decrease in gene expression. This period signals the end of maturation and the beginning of senescence of chili pepper fruit. The transcriptome at 60 DAA was the most specialized and least diverse of the four states sampled.
| S-EPMC3936869 | biostudies-literature
Project description:Gene co-expression networks are powerful tools to understand functional interactions between genes. However, large co-expression networks are difficult to interpret and do not guarantee that the relations found will be true for different genotypes. Statistically verified time expression profiles give information about significant changes in expressions through time, and genes with highly correlated time expression profiles, which are annotated in the same biological process, are likely to be functionally connected. A method to obtain robust networks of functionally related genes will be useful to understand the complexity of the transcriptome, leading to biologically relevant insights. We present an algorithm to construct gene functional networks for genes annotated in a given biological process or other aspects of interest. We assume that there are genome-wide time expression profiles for a set of representative genotypes of the species of interest. The method is based on the correlation of time expression profiles, bound by a set of thresholds that assure both, a given false discovery rate, and the discard of correlation outliers. The novelty of the method consists in that a gene expression relation must be repeatedly found in a given set of independent genotypes to be considered valid. This automatically discards relations particular to specific genotypes, assuring a network robustness, which can be set a priori. Additionally, we present an algorithm to find transcription factors candidates for regulating hub genes within a network. The algorithms are demonstrated with data from a large experiment studying gene expression during the development of the fruit in a diverse set of chili pepper genotypes. The algorithm is implemented and demonstrated in a new version of the publicly available R package "Salsa" (version 1.0).
| S-EPMC10005043 | biostudies-literature
Project description:Background The set of all mRNA molecules present in a cell constitute the transcriptome. The transcriptome varies depending on cell type as well as in response to internal and external stimuli during development. Chili pepper is an economically and culturally important horticultural crop as well as a good model for the study of secondary metabolism during fruit development. Here we present a study of the changes that occur in the transcriptome of chili pepper fruit during development and ripening. Results RNA-Seq was used to obtain transcriptomes of whole Serrano-type chili pepper fruits (Capsicum annuum L.; 'Tampiqueno 74') collected at 10, 20, 40 and 60 days after anthesis (DAA). 15,550,468 Illumina MiSeq reads were assembled de novo into 34,066 chili genes. We classified the expression patterns of individual genes as well as genes grouped into Biological Process ontologies and Metabolic Pathway categories using statistical criteria. For the analyses of gene groups we added the weighted expression of individual genes. This method was effective in interpreting general patterns of expression changes and increased the statistical power of the analyses. Subsets of genes were expressed only at a single time point sampled (1,278, 1,596, 1,519 and 1,583 genes at 10, 20, 40 and 60 DAA, respectively). We also estimated the variation in diversity and specialization of the transcriptome during chili pepper development. Approximately 17% of genes exhibited a significant change of expression in at least one of the intervals sampled. In contrast, significant differences in approximately 63% of the Biological Processes and 80% of the Metabolic Pathways studied were detected in at least one interval. Confirming previous reports, genes related to capsaicinoid and ascorbic acid biosynthesis were significantly upregulated at 20 DAA while those related to carotenoid biosynthesis were highly expressed in the last period of fruit maturation (40-60 DAA). Our RNA-Seq data was validated by examining the expression of nine genes involved in carotenoid biosynthesis by qRT-PCR. Conclusions In general, more profound changes in the chili fruit transcriptome were observed in the intervals between 10 to 20 and 40 to 60 DAA. The last interval, between 40 to 60 DAA, included 49% of all significant changes detected, and was characterized predominantly by a global decrease in gene expression. This period signals the end of maturation and the beginning of senescence of chili pepper fruit. The transcriptome at 60 DAA was the most specialized and least diverse of the four states sampled. RNA-seq libraries of whole chili pepper (Capsicum annuum Serrano 'Tampiqueno 74' landrace) were prepared from fruits at 10, 20, 40 and 60 days after anthesis (DAA). Two biological replicates of each fruit state were prepared (8 libraries in total). Libraries were sequenced in the Illumina MiSeq platform. The title of the libraries are: <DAA>repbio<#> where <DAA> are the days after anthesis (10, 20, 40 or 60) and <#> is the number of biological replicate, 1 or 2. Details follow. Biological material and RNA extraction Capsicum annuum Serrano 'Tampiqueno 74' seeds were germinated and the seedlings were cultivated until maturity under greenhouse conditions in a completely randomized experimental design at Cinvestav-Unidad Irapuato (Guanajuato, Mexico). The plants were grown during the spring and summer, and individual flowers were tagged at anthesis. Chili pepper fruits were randomly collected from different plants at 10, 20, 40 and 60 DAA. After sampling, the fruits were cleaned with ethanol immediately frozen in liquid nitrogen and stored at -80C until further use. For total RNA extractions, 10 fruits at the 10 DAA developmental stage and 5 fruits from each of the 20, 40 and 60 DAA stages were randomly selected from the pool of all harvested fruits. Whole fruits (pericarp, placenta and seeds) were ground in liquid nitrogen with a mortar and pestle to form a fine uniform powder. Samples were mixed vigorously and 100 mg aliquots were measured for each RNA extraction. The process was repeated with different sets of fruits in order to obtain two independent biological replicates at each developmental stage. A NucleoSpin RNA Plant kit (Macherey-Nagel) was used for total RNA extraction and contaminating genomic DNA was removed by DNase I (Macherey-Nagel) treatment following the manufacturers' protocols. Total RNA concentration was quantified using a NanoDrop ND-1000 spectrophotometer (Nano-Drop, Wilmington, DE, USA) and RNA quality was evaluated by gel electrophoresis on 1.0% denaturing agarose gels. In addition, aliquots of RNA were run on an Agilent 2100 Bioanalyzer using RNA 6000 chips (Agilent, Santa Clara, CA, USA) to test the RNA integrity number (RIN). All eight samples had RIN values higher than 8.7. Thirty ?g of total RNA from each of the eight samples (two biological replicates of four fruit developmental stages) was used for cDNA library preparation. Library construction and sequencing The eight total RNA samples (two biological replicates from chili pepper fruits at 10, 20, 40 and 60 DAA) were prepared for RNA-Seq using the Illumina TruSeq RNA Sample Preparation v2 Guide following the manufacturer's instructions. Briefly, mRNA was purified from 20?g of total RNA using poly-T oligo- attached magnetic beads using two rounds of purification. During the second elution of the poly-A RNA, mRNA was fragmented using divalent cations under elevated temperature and primed for cDNA synthesis. The cleaved RNA fragments were primed with random hexamers and reverse transcribed into single-stranded cDNA using reverse transcriptase. In the next step, the RNA template was removed and the complementary cDNA strand was synthesized using RNAse H and DNA polymerase I, respectively. The overhangs that resulted from fragmentation were polished into blunt ends using an End Repair Mix (consisting of T4 DNA polymerase, Klenow fragment and T4 polynucleotide kinase). A single T nucleotide was added on the 3' end of the adapter for ligating the adapter to the cDNA fragments. Indexing adapters were ligated to the ends of the cDNAs using T4 DNA ligase, preparing them for hybridization onto a flow cell. Finally, the DNA fragments with adapter molecules at both ends were amplified by PCR to enrich the amount of DNA in the library. PCR was performed with a PCR primer cocktail that anneals to the ends of the adapters. Quantity and quality of the DNA libraries was assessed using Agilent DNA-1000 chips on an Agilent 2100 Bioanalyzer. The 8 cDNA libraries were pooled and simultaneously sequenced from both 5’ and 3’ ends using the Illumina MiSeq System platform according to the manufacturer's instructions. We performed three sequencing runs (technical replicates) with the aim of increase the sequencing depth. 150 bp paired-end reads were obtained in each sequencing run. Fluorescent image processing, base-calling and quality value calculations for each of the three runs were performed using Illumina MiSeq Control Software. Data were deposited at the NCBI (GEO database under series record GSE54123).
2014-02-21 | E-GEOD-54123 | biostudies-arrayexpress
Project description:Gene expression is the primary molecular phenotype and can be estimated in specific organs or tissues at particular times. Here we analyzed genome-wide inheritance of gene expression in fruits of chili pepper (Capsicum annuum L.) in reciprocal crosses between a domesticated and a wild accession, estimating this parameter during fruit development. We defined a general hierarchical schema to classify gene expression inheritance which can be employed for any quantitative trait. We found that inheritance of gene expression is affected by both, the time of fruit development as well as the direction of the cross, and propose that such variations could be common in many developmental processes. We conclude that classification of inheritance patterns is important to have a better understanding of the mechanisms underlying gene expression regulation, and demonstrate that sets of genes with specific inheritance pattern at particular times of fruit development are enriched in different biological processes, molecular functions and cell components. All curated data and functions for analysis and visualization are publicly available as an R package.
| S-EPMC8609037 | biostudies-literature
Project description:Twelve chili pepper accessions, six domesticated, four wild and two F1 crosses were studied. RNA-Seq experiments were performed with fruits from each accession at 7 different times after anthesis. Additionally, samples of seedlings from two accessions were evaluated. The data set is comprised by 179 samples, that in total have more than 3 billion reads map to the Capsicum annuum genome.
2021-03-16 | GSE165448 | GEO
Project description:Chili pepper (Capsicum spp.) is an important crop, as well as a model for fruit development studies and domestication. Here, we performed a time-course experiment to estimate standardized gene expression profiles with respect to fruit development for six domesticated and four wild chili pepper ancestors. We sampled the transcriptomes every 10 days from flowering to fruit maturity, and found that the mean standardized expression profiles for domesticated and wild accessions significantly differed. The mean standardized expression was higher and peaked earlier for domesticated vs. wild genotypes, particularly for genes involved in the cell cycle that ultimately control fruit size. We postulate that these gene expression changes are driven by selection pressures during domestication and show a robust network of cell cycle genes with a time shift in expression, which explains some of the differences between domesticated and wild phenotypes.
| S-EPMC8003350 | biostudies-literature
Project description:The process of domestication requires the rapid transformation of the wild morphology into the cultivated forms that humans select for. This process often takes place through changes in the regulation of genes, yet, there is no definite pattern on the role of cis- and trans-acting regulatory variations in the domestication of the fruit among crops. Using allele-specific expression and network analyses, we characterized the regulatory patterns and the inheritance of gene expression in wild and cultivated accessions of chili pepper, a crop with remarkable fruit morphological variation. We propose that gene expression differences associated to the cultivated form are best explained by cis-regulatory hubs acting through trans-regulatory cascades. We show that in cultivated chili, the expression of genes associated with fruit morphology is partially recessive with respect to those in the wild relative, consistent with the hybrid fruit phenotype. Decreased expression of fruit maturation and growth genes in cultivated chili suggest that selection for loss-of-function took place in its domestication. Trans-regulatory changes underlie the majority of the genes showing regulatory divergence and had larger effect sizes on gene expression than cis-regulatory variants. Network analysis of selected cis-regulated genes, including ARP9 and MED25, indicated their interaction with many transcription factors involved in organ growth and fruit ripening. Differentially expressed genes linked to cis-regulatory variants and their interactions with downstream trans-acting genes have the potential to drive the morphological differences observed between wild and cultivated fruits and provide an attractive mechanism of morphological transformation during the domestication of the chili pepper.
| S-EPMC7253206 | biostudies-literature