Dataset Information

De novo assembly and comparative analysis of the transcriptome of embryogenic callus formation in bread wheat (Triticum aestivum L.).

ABSTRACT: During asexual reproduction the embryogenic callus can differentiate into a new plantlet, offering great potential for fostering in vitro culture efficiency in plants. The immature embryos (IMEs) of wheat (Triticum aestivum L.) are more easily able to generate embryogenic callus than mature embryos (MEs). To understand the molecular process of embryogenic callus formation in wheat, de novo transcriptome sequencing was used to generate transcriptome sequences from calli derived from IMEs and MEs after 3d, 6d, or 15d of culture (DC).In total, 155 million high quality paired-end reads were obtained from the 6 cDNA libraries. Our de novo assembly generated 142,221 unigenes, of which 59,976 (42.17%) were annotated with a significant Blastx against nr, Pfam, Swissprot, KOG, KEGG, GO and COG/KOG databases. Comparative transcriptome analysis indicated that a total of 5194 differentially expressed genes (DEGs) were identified in the comparisons of IME vs. ME at the three stages, including 3181, 2085 and 1468 DEGs at 3, 6 and 15 DC, respectively. Of them, 283 overlapped in all the three comparisons. Furthermore, 4731 DEGs were identified in the comparisons between stages in IMEs and MEs. Functional analysis revealed that 271transcription factor (TF) genes (10 overlapped in all 3 comparisons of IME vs. ME) and 346 somatic embryogenesis related genes (SSEGs; 35 overlapped in all 3 comparisons of IME vs. ME) were differentially expressed in at least one comparison of IME vs. ME. In addition, of the 283 overlapped DEGs in the 3 comparisons of IME vs. ME, excluding the SSEGs and TFs, 39 possessed a higher rate of involvement in biological processes relating to response to stimuli, in multi-organism processes, reproductive processes and reproduction. Furthermore, 7 were simultaneously differentially expressed in the 2 comparisons between the stages in IMEs, but not MEs, suggesting that they may be related to embryogenic callus formation. The expression levels of genes, which were validated by qRT-PCR, showed a high correlation with the RNA-seq value.This study provides new insights into the role of the transcriptome in embryogenic callus formation in wheat, and will serve as a valuable resource for further studies addressing embryogenic callus formation in plants.

SUBMITTER: Chu Z

PROVIDER: S-EPMC5735865 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature

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De novo assembly and comparative analysis of the transcriptome of embryogenic callus formation in bread wheat (Triticum aestivum L.).

Chu Zongli Z Chen Junying J Sun Junyan J Dong Zhongdong Z Yang Xia X Wang Ying Y Xu Haixia H Zhang Xiaoke X Chen Feng F Cui Dangqun D

BMC plant biology 20171219 1

<h4>Background</h4>During asexual reproduction the embryogenic callus can differentiate into a new plantlet, offering great potential for fostering in vitro culture efficiency in plants. The immature embryos (IMEs) of wheat (Triticum aestivum L.) are more easily able to generate embryogenic callus than mature embryos (MEs). To understand the molecular process of embryogenic callus formation in wheat, de novo transcriptome sequencing was used to generate transcriptome sequences from calli derived ...[more]

PMID: 29258440

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Project description:BACKGROUND: Phosphorus (P) is an essential macronutrient for plant growth and development. To modulate their P homeostasis, plants must balance P uptake, mobilisation, and partitioning to various organs. Despite the worldwide importance of wheat as a cultivated food crop, molecular mechanisms associated with phosphate (Pi) starvation in wheat remain unclear. To elucidate these mechanisms, we used RNA-Seq methods to generate transcriptome profiles of the wheat variety 'Chinese Spring' responding to 10 days of Pi starvation. RESULTS: We carried out de novo assembly on 73.8 million high-quality reads generated from RNA-Seq libraries. We then constructed a transcript dataset containing 29,617 non-redundant wheat transcripts, comprising 15,047 contigs and 14,570 non-redundant full-length cDNAs from the TriFLDB database. When compared with barley full-length cDNAs, 10,656 of the 15,047 contigs were unalignable, suggesting that many might be distinct from barley transcripts. The average expression level of the contigs was lower than that of the known cDNAs, implying that these contigs included transcripts that were rarely represented in the full-length cDNA library. Within the non-redundant transcript set, we identified 892-2,833 responsive transcripts in roots and shoots, corresponding on average to 23.4% of the contigs not covered by cDNAs in TriFLDB under Pi starvation. The relative expression level of the wheat IPS1 (Induced by Phosphate Starvation 1) homologue, TaIPS1, was 341-fold higher in roots and 13-fold higher in shoots; this finding was further confirmed by qRT-PCR analysis. A comparative analysis of the wheat- and rice-responsive transcripts for orthologous genes under Pi-starvation revealed commonly upregulated transcripts, most of which appeared to be involved in a general response to Pi starvation, namely, an IPS1-mediated signalling cascade and its downstream functions such as Pi remobilisation, Pi uptake, and changes in Pi metabolism. CONCLUSIONS: Our transcriptome profiles demonstrated the impact of Pi starvation on global gene expression in wheat. This study revealed that enhancement of the Pi-mediated signalling cascade using IPS1 is a potent adaptation mechanism to Pi starvation that is conserved in both wheat and rice and validated the effectiveness of using short-read next-generation sequencing data for wheat transcriptome analysis in the absence of reference genome information.

Project description:Phosphorus (P) is an essential macronutrient for plant growth and development, and a plant must balance P uptake, mobilisation, and partitioning to various organs to modulate P homeostasis. The underlying molecular mechanisms of wheat under phosphate (Pi) starvation conditions remain elusive despite wheat is an important cultivated food crop worldwide. We generated transcriptome profiles of wheat variety Chinese Spring (CS) in response to Pi starvation (-P) for 10 days using RNA-Seq methods.We used 73.8 million high-quality reads obtained from libraries for de novo assembly. Overall, a set containing 29,617 non-redundant wheat transcripts was constructed with 15,047 assemblies and 14,570 non-redundant, full-length cDNAs in TriFLDB. Of the transcripts, 10,656 of the 15,047 assemblies were unaligned against barley full-length cDNAs, suggesting that many of them might be distinct of barley transcripts. The distribution of average expression levels for the assembly was lower than that for cDNAs, suggesting that the assemblies contained rare transcripts limited availability using full-length cDNA library construction methods. Within the transcript set, we identified 892-2,833 up- or downregulated transcripts in root and shoot, including 18.9-40.5% assemblies, uncovered by cDNAs in TriFLDB under -P in each condition. In the results, the expression level of wheat IPS1 (induced by phosphate starvation 1) homolog, TaIPS1, was 358.6-fold higher in the root and 12.6-fold higher in the shoot, which was confirmed by qRT-PCR analysis. Comparative analysis between wheat (a rice orthologue) and rice responsive transcripts under -P conditions showed that 39 (root) and 21 (shoot) responsive transcripts were commonly upregulated, and most of them seemed to be involved in a general response to -P; IPS1-mediated signal transduction and its downstream function such as Pi remobilization, Pi uptake and change metabolism.Our transcriptome profiling demonstrates the impact of -P in wheat. This study shows that enhancing the Pi-mediated signalling pathway through IPS1 is conserved as a potent adaptation to Pi starvation in both wheat and rice, and also that our constructed strategy using short read next generation sequencing (NGS) data was successful for the transcriptome analysis in wheat without reference genome. Note: Samples in SRA were assigned the same sample accession. This is incorrect as there are different samples, hence “Source Name” was replaced with new values. Comment[ENA_SAMPLE] contains the original SRA sample accessions.

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Project description:BackgroundHigh post-anthesis (p.a) temperatures reduce mature grain weights in wheat and other cereals. However, the causes of this reduction are not entirely known. Control of grain expansion by the maternally derived pericarp of the grain has previously been suggested, although this interaction has not been investigated under high p.a. temperatures. Down-regulation of pericarp localised genes that regulate cell wall expansion under high p.a. temperatures may limit expansion of the encapsulated endosperm due to a loss of plasticity in the pericarp, reducing mature grain weight. Here the effect of high p.a. temperatures on the transcriptome of the pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed alongside grain moisture dynamics during early grain development and mature grain weight.ResultsHigh p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the grain's ability to accumulate water, with total grain moisture and percentage grain moisture content being significantly reduced from 14daa onwards. Mature grain weight was also significantly reduced by the same high p.a. temperatures applied from 6daa for 4-days or more, in a separate experiment. Comparison of our RNA-Seq data from whole grains, with existing data sets from isolated pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the pericarp and significantly down-regulated under high p.a. temperatures, including endoglucanase, xyloglucan endotransglycosylases and a β-expansin. An over-representation of genes involved in the 'cuticle development' functional pathway that were expressed in the pericarp and affected by high p.a. temperatures was also observed.ConclusionsHigh p.a. temperature induced down-regulation of genes involved in regulating pericarp cell wall expansion. This concomitant down-regulation with a reduction in total grain moisture content and grain weight following the same treatment period, adds support to the theory that high p.a. temperatures may cause a reduction in mature grain weight as result of decreased pericarp cell wall expansion.

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Dataset Information

De novo assembly and comparative analysis of the transcriptome of embryogenic callus formation in bread wheat (Triticum aestivum L.).

Publications

De novo assembly and comparative analysis of the transcriptome of embryogenic callus formation in bread wheat (Triticum aestivum L.).

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