Project description:We explored the transcriptomic changes of synthetic Brassica allohexaploid by comparing to its parents using a high-throughput RNA-Seq method. A total of 35644409 sequence reads were generated, and 32642 genes were aligned from the data. There were 29260, 29060 and 29697 genes identified in Brassica rapa, Brassica carinata, and Brassica allohexaploid, respectively. We screened differentially expressed genes (DEGs) by a standard of two-fold or greater change in expression and false discovery rate (FDR) no more than 0.001. As a result, 7397 DEGs were detected between Brassica hexaploid and its parents. A large proportion of the 3184 DEGs between Brassica hexaploid and its paternal parent B. rapa was involved in biosynthesis of secondary metabolites, plant-pathogen interaction, photosynthesis, and circadian rhythm. Between Brassica hexaploid and its maternal parent B. carinata, 2233 DEGs were screened. A lot of them had functions of plant-pathogen interaction, plant hormone signal transduction, ribosome, limonene and pinene degradation, photosynthesis, and also biosynthesis of secondary metabolites. In addition, we found many transcription factor genes, methyltransferase and methylation genes that showed differential expression between Brassica hexaploid and its parents. Leaf mRNA profiles of Brassica rapa, Brassica carinata, and Brassica allohexaploid
Project description:We explored the transcriptomic changes of synthetic Brassica allohexaploid by comparing to its parents using a high-throughput RNA-Seq method. A total of 35644409 sequence reads were generated, and 32642 genes were aligned from the data. There were 29260, 29060 and 29697 genes identified in Brassica rapa, Brassica carinata, and Brassica allohexaploid, respectively. We screened differentially expressed genes (DEGs) by a standard of two-fold or greater change in expression and false discovery rate (FDR) no more than 0.001. As a result, 7397 DEGs were detected between Brassica hexaploid and its parents. A large proportion of the 3184 DEGs between Brassica hexaploid and its paternal parent B. rapa was involved in biosynthesis of secondary metabolites, plant-pathogen interaction, photosynthesis, and circadian rhythm. Between Brassica hexaploid and its maternal parent B. carinata, 2233 DEGs were screened. A lot of them had functions of plant-pathogen interaction, plant hormone signal transduction, ribosome, limonene and pinene degradation, photosynthesis, and also biosynthesis of secondary metabolites. In addition, we found many transcription factor genes, methyltransferase and methylation genes that showed differential expression between Brassica hexaploid and its parents.
Project description:Bread wheat is allohexaploid with 16 Gb genome, which has large intergenic region with abundant TEs and regulatory sequences . Our results give insight into the connections between chromatin modifications and transcriptional regulatory activity and provide the first systematic epigenomic map for functional annotation of the allohexaploid wheat genome.
Project description:Cytosine DNA methylation (mC) can silence transposable elements (TEs) and regulate gene expression. However, the mechanism and function of DNA methylation reprogramming during plant development are still largely unknown. To explore the DNA methylation dynamics during the male sexual-lineage development in the Brassicaceae family, we assessed the mC level in meiocyte, microspore and pollen of a Brassica rapa doubled haploid (DH) line by whole genome bisulfite sequencing (WGBS). Analysis of global mC profiles showed that significant reprogramming of CHH methylation occurred in the Brassica rapa male sex cells, similar to that observed in Arabidopsis. Analysis of differential methylation sites identified specific methylation loci in sex cells that can target and possibly regulate gene expression, suggesting a mechanism consistent with that of Arabidopsis. Quite a few long terminal repeat (LTR) transposable elements were activated in meiocyte and microspore, which correlated with reduced DNA methylation. Expression analysis of key genes that affect DNA methylation showed that active methylation and demethylation occurred during male sexual lineage development. These results suggest a conserved DNA methylation reprogramming mechanism during Brassica rapa male sex lineage development. The transcriptome and DNA methylome data obtained will also be useful for other mechanism studies in Brassica rapa.
Project description:The three subgenomes (B, A and D) of common wheat (2n=6x=42) are largely intact, which makes extraction of the BBAA subgenomes as organismally independent genomes possible. Availability of such novel extracted tetraploid wheat (Extracted-tetra) provides a unique opportunity to study whether and to what extent the BBAA subgenomes of common wheat have been irreversibly modified, as well as its attendant biological consequences, during their evolutionary trajectory as allohexaploidy. We report here that the extracted-tetra is stable in karyotype but with severely deteriorated phenotypes. Microarray-based transcriptome analysis revealed a substantial portion of differentially expressed genes (down- or up-regulation) between extracted and natural tetraploid wheat, Triticum turgidum, which exceeded the transcriptome divergence at tetraploid level, implying reinforced effects of allopolyploidization and domestication at the allohexaploid level. Great majority of the differentially expressed genes showed additive expression in a resynthesized allohexaploid wheat (parented by Extracted-tetra), indicating transcriptome modifications to the BBAA subgenomes are largely irreversible. Analysis of a newly synthesized allohexaploid wheat (parented by T. turgidum) suggests that whereas most of the modified genes are accrued evolutionary changes, some showed immediate regulation post-allohexaploidization and evolutionary perseverance. Homeologue-specific pyrosequencing of 44 genes revealed either concordant or independent expression changes to the B and A homeologues. The Extracted-tetra vs.T. turgidum down-regulated genes showed enrichment for distinct GO categories. Structurally, the three constituent subgenomes of common wheat, BB, AA and DD, are largely intact with only a few inter-subgenomic translocations. Because of these unique attributes, it is feasible to extract the BBAA subgenomes from the common wheat BBAADD genome by hybridization to a durum line and repeated back-crossing to the hexaploid parent, restituting a novel type of extracted tetraploid wheat, namely Extracted-tetr, with a genome constitution BBAA, virtually identical to the subgenomes BBAA of its common wheat donor. Availability of the extracted-tetra, the resynthesized allohexaploid wheat parented by the extracted-tetra, and newly synthesized allohexaploid wheat parented by natural tetraploid wheat, T. turgidum, provides an excellent system to address the issues of whether and to what extent transcriptome modifications to the BBAA subgenomes of common wheat have occurred since its formation ca. 10,000 years ago, timing of the modifications, and their biological consequences. Here, we have addressed these issues by microarray-based transcriptome analysis.
Project description:Understanding the regulation of lipid metabolism is vital for genetic engineering of Brassica napus (B. napus) to increase oil yield or modify oil composition. We report the application of Illumina Hiseq 2000 for transcriptome profiling of seeds of B. napus at different developmental stages, which may uncover the dynamic changes in lipid metabolism and reveal key genes involved in lipid biosynthesis and degradation. Total RNA from developing seeds at 2, 4, 6, and 8 weeks after pollination (WAP) were isolated and sequenced separately. The gene expression levels of all samples were quantified and normalized by the DESeq normalization. We found that the biosynthesis of fatty acids is a dominant cellular process from 2 to 6 WAP, while the degradation mainly happens after 6 WAP. Two genes, encoding for acetyl-CoA carboxylase and acyl-ACP desaturase, might be critical for fatty acid biosynthesis in oil rape seeds. This study provides insight into the mechanism underlying lipid metabolism and reveals candidate genes that are worthy of further investigation for their values in genetic engineering of B. napus. Whole Transcriptome profiling of developing Brassica napus seeds at 2, 4, 6, 8 WAP by RNA sequencing using Illumina HiSeq 2000.
Project description:The mapping and functional analysis of quantitative traits in Brassica rapa can be greatly improved with the availability of physically positioned, gene-based genetic markers and accurate genome annotation. In this study, deep transcriptome RNA sequencing (RNA-Seq) of Brassica rapa was undertaken with two objectives: SNP detection and improved transcriptome annotation. We performed SNP detection on two varieties that are parents of a mapping population to aid in development of a marker system for this population and subsequent development of high-resolution genetic map. An improved Brassica rapa transcriptome was constructed to detect novel transcripts and to improve the current genome annotation. Deep RNA-Seq of two Brassica rapa genotypesâR500 (var. trilocularis, Yellow Sarson) and IMB211 (a rapid cycling variety)âusing eight different tissues (root, internode, leaf, petiole, apical meristem, floral meristem, silique, and seedling) grown across three different environments (growth chamber, greenhouse and field) and under two different treatments (simulated sun and simulated shade) generated 2.3 billion high-quality Illumina reads. In this experiment, two pools were made, with one pool consisting of 66 samples collected from growth chamber and another pool consisting of 60 samples collected from greenhouse and field. Each pool was sequenced on eight lanes (total 16 lanes) of an Illumina Genome Analyzer (GAIIx) as 100-bp paired end reads.