Dissecting the temporal genetic networks programming soybean embryo development from embryonic morphogenesis to post-germination
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ABSTRACT: To understand the molecular events underlying seed desiccation and germination, we performed transcriptome analysis of soybean (Glycine max) embryos at three seed developmental stages (early, mid and late desiccation), mature dry seeds, and three germination stages (3, 16 and 27 hour-after-imbibition).
Project description:To understand the molecular events underlying seed maturation, quiescence and germination, we performed transcriptome analysis of soybean (Glycine max) embryos at four seed developmental stages (cotyledon, early, mid and late maturation), mature dry seeds, and seedlings, eight days after seed sowing.
Project description:Purpose: To identify the potential genes that regulate seed germination speed in maize, we performed a time-series transcriptome analysis with two inbred maize lines (72-3 fast germination, F9721 slow germination) during the seed germination and compared the differentially expressed genes (DEGs) in transcriptome with genes identified by GWAS Methods: Methods: mRNA profiles of two maize inbred lines 72-3 and F9721 showing divergent seed germination at six stages during germination were generated by deep sequencing, in triplicate, using Illumina Hiseq2500. The sequence reads that passed quality filters were analyzed at the gene level. Hisat2 was used to align clean reads to maize B73 reference genome, and HTSeq was used to count transcript abundance. DESeq2 models were used to compare DEGs at each germination stage within or between samples Results: Comparative transcriptome study identified 12 hours after imbibition (HAI) as the critical stage responsible for the variation of germination speed. The DEGs between 72-3 and F9721 were mainly enriched in metabolic pathways, biosynthesis of secondary metabolites, oxidoreductase activity pathways, hormone signal transduction, and amino acid transporter activity pathways Conclusions: Combined with evidence from gene expression data, GWAS, and gene synteny with other model species, we finally anchored three genes as the likely candidate genes regulating germination speed in maize
Project description:Seed germination is characterized by a constant change of gene expression across different time points. These changes are related to specific processes, which eventually determine the onset of seed germination. To get a better understanding on the regulation of gene expression during seed germination, we measured gene expression levels of Arabidopsis thaliana Bay x Sha recombinant inbred lines (RILs) at four important seed germination stages (primary dormant, after-ripened, six-hour after imbibition, and radicle protrusion stage) using. We mapped the eQTL of the gene expression and the result displayed the distinctness of the eQTL landscape for each stage. We found several eQTL hotspots across stages associated with the regulation of expression of a large number of genes. Together, we have revealed that the genetic regulation of gene expression is dynamic along the course of seed germination.
Project description:How epigenetics is involved in the transition from seed maturation to seed germination largely remains elusive. To uncover the possible role of epigenetics in gene expression during the transition from seed maturation to seed germination in soybean, the transcriptome of cotyledons from four stages of soybean seed maturation and germination, including mid-late maturation, late maturation, seed dormancy and seed germination, were profiled by Illumina sequencing. For the genes that are quantitatively regulated at the four stages, two antagonistic epigenetic marks, H3K4me3 and H3K27me3, together with the binding of RNA polymerase II, were investigated at the four stages by chromatin immunoprecipitation (ChIP). For 10 out of 16 genes examined, the relative enrichment of histone modification marks (H3K4me3 and H3K27me3) and RNA polymerase II binding on their promoter regions correlates well with their relative expression levels at four stages, suggesting the involvement of epigenetics in transcriptional regulation. A striking finding is that seed germination-specific genes start to show open chromatin (H3K4me3) during late seed maturation although their transcripts do not accumulate, which is further supported by RNA polymerase II binding. Together, our results provide the first evidence that seed germination genes can be primed for transcription (open chromatin and RNA polymerase II binding) during seed maturation, highlighting that the transition from seed maturation to seed germination starts at late seed maturation stages at both the genetic and epigenetic levels. Illumina sequencing of transcripts from cotyledons of mid-maturation (B1 stage) and late maturation (AA1 stage) seeds, whole dry seeds, and cotyledons of seedlings six days after imbibition.
Project description:Purpose: A time-course transcriptome study to identify probable GA-responsive genes in soybean embryonic axes during seed germination. Methods: Seeds were germinated in the presence or absence of 200 µM PBZ. Seeds were germinated in 28°C temperature and 12/12h photoperiod (dark/light) and harvested at 12, 24 and 36 hours after imbibition (HAI). Three biological replicates were performed. Results: Identification of GA-responsive genes during germination in Glycine max.
Project description:Histone acetylation is involved in the regulation of gene expression in plants and eukaryotes. Histone deacetylases (HDACs) are enzymes that catalyze the removal of acetyl groups from histones, which is associated with the repression of gene expression. To study the role of histone acetylation in the regulation of gene expression during seed germination, trichostatin A (TSA), a specific inhibitor of histone deacetylase, was used to treat imbibing Arabidopsis thaliana seeds. GeneChip arrays were used to show that TSA induces up-regulation of 45 genes and down-regulation of 27 genes during seed germination. Eight TSA-up-regulated genes were selected for further analysis - RAB18, RD29B, ATEM1, HSP70 and four late embryogenesis abundant protein genes (LEA). A gene expression time course shows that these eight genes are expressed at high levels in the dry seed and repressed upon seed imbibition at an exponential rate. In the presence of TSA, the onset of repression of the eight genes is not affected but the final level of repressed expression is elevated. Chromatin immunoprecipitation and HDAC assays show that there is a transient histone deacetylation event during seed germination at one day after imbibition, which serves as a key developmental signal that affects the repression of the eight genes. This SuperSeries is composed of the SubSeries listed below.
Project description:affy_rice_2011_03 - affy_compartimentation_rice_albumen_embryon - During germination, the rice seed goes from a dry quiescent state to an active metabolism. As with all cereals, the rice seed is highly differentiated between the embryo (that will give rise to the future plantlet) and the endosperm (that contains the seed storage compounds and that will degenerate). The molecular mechanisms operating in the rice seed embryo have begun to be described. Yet, very few studies have focused specifically on the endosperm during the germination process. In particular, the endosperm is mostly addressed with regards to its storage proteins but we have detected a large protein diversity by two-dimensional electrophoresis. Similarly, the endosperm is rich in total RNA which suggest that gene expression coming from seed maturation could play a role during the germination process. In this context, we want to compare the transcriptome of the embryo and the endosperm during rice seed germination. -We germinate rice seeds of the first sequenced rice cultivar i.e. Nipponbare during 0, 4, 8, 12, 16 and 24h of imbibition in sterile distilled water. Germination occurs under constant air bubbling, in the dark at 30°C. These rice seeds are then manually dissected into embryo and endosperm fractions. -The embryo-derived samples are abbreviated in “E” while the endosperm samples are abbreviated “A”. The germination time-point is indicated after the letter (e.g. E8 for embryo samples harvested after 8 hours of germination). Finally, the biological repetition number is indicated before the letter and the time digit (e.g. 1-E8 for an embryo sample from the first repetition at 8 hours of imbibition).
Project description:Seed germination involves transition from desiccation tolerance to sensitivity during early stages of seedling establishment accompanied by comprehensive changes of metabolome and proteome. Germination of Arabidopsis seeds was investigated over 72 h with special focus on the heat-stable proteome including late embryogenesis abundant (LEA) proteins together with changes of primary metabolites. Six metabolites in dry seeds important for seed longevity decreased during germination and seedling establishment, while all other metabolites increased simultaneously with activation of growth and development. In the heat stable proteome an almost equal fractioning of ordered and intrinsically disordered proteins (IDP) was discovered. Highly disordered proteins were assigned to functional bins development, protein, RNA and stress. Thermal stable proteins were related to a multitude of active biological processes. The majority of LEA proteins decreased during germination and seedling establishment in parallel to reduced desiccation tolerance. Five germination specific dehydrins were identified most likely providing stress tolerance. Network analysis of common proteins and metabolites over all time points revealed a tight network of LEA proteins with five hub LEAs with high connectivity. Connections to proteins such as Rubisco large subunit and seed storage proteins were discovered. Insights into the heat-stable proteome – metabolome network during seed germination are provided.
Project description:Wheat seed germination is highly related to seedling survival rate and subsequent vegetative growth,and therefore directly affects the conformation of wheat yield and quality. So wheat seed germination is not only important to itself, but the whole human society. However, due to the large genome size, many studies related to wheat seed are very complex and uncompleted. Transcriptome analysis of elite Chinese bread wheat cultivar Jimai 20 may provides a comprehensive understanding of wheat seed germination. Seed germination involves in the regulation of large number of genes, whether these genes are normal activated or not is very important to seed germination. We performed microarray analysis using the Affymetrix Gene Chip to reveal the gene expression profiles in five phases of wheat cultivar Jimai 20 seed germination. Our results provide a new insights into the thoroughly metabolic changes of seed germination as well as the relationship between some significant genes. The five groups including germinating seeds were harvest at five successive phases, which were 0 (P0), 12 (P1), 24 (P2), 36 (P3), 48 (P4) hour after imbibition respectively. Three independent experiments were performed for each group.
Project description:Seed germination is a complex trait determined by the interaction of hormonal, metabolic, genetic, and environmental components. Variability of this trait in crops has a big impact on seedling establishment and yield in the field. Classical studies of this trait in crops have focused mainly on the analyses of one level of regulation in the cascade of events leading to seed germination. We have carried out an integrative and extensive approach to deepen our understanding of seed germination in Brassica napus by generating transcriptomic, metabolic and hormonal data at different stages upon seed imbibition. Deep phenotyping of different seed germination associated traits in six winter-type B. napus accessions has revealed that seed germination kinetics, in particular seed germination speed, are major contributors to the variability of this trait. Metabolic profiling of these accessions has allowed us to describe a common pattern of metabolic change and to identify the levels of malate and aspartate metabolites as putative metabolic markers to estimate germination performance. Additionally, analysis of seed content of different hormones suggests that hormonal balance between ABA, GA and IAA at crucial time points during this process might underlie seed germination differences in these accessions. In this study, we have also defined the major transcriptome changes accompanying the germination process in B. napus. Furthermore, we have observed that earlier activation of key germination regulatory genes seems to generate the differences in germination speed observed between accessions in B. napus. Finally, we have found that protein-protein interactions between some of these key regulators are conserved in B. napus suggesting a shared regulatory network with other plants species. Altogether, our results provide a comprehensive and detailed picture of seed germination dynamics in oilseed rape. This new framework will be extremely valuable, not only to evaluate germination performance of B. napus accessions, but also to identify key targets for crop improvement in this important process.