Dataset Information

Nutritional functions of the funiculus in Brassica napus seed maturation revealed by transcriptome and dynamic metabolite profile analyses.

ABSTRACT: The funiculus provides the sole channel of communication between the seed and the parent plant; however, little is known about its role in nutrient supply during seed maturation. Here, we investigated the dynamic metabolite profiles of the funiculus during seed maturation in Brassica napus. The funiculus was fully developed at 21 days after flowering (DAF), but the levels of nutrients, including carbohydrates, fatty acids, and amino acids, increased rapidly from 21 to 35 DAF. Orthogonal partial least squares discriminant analysis and correlation analysis identified 37 metabolites that correlated closely with seed fresh weight. To determine the influence of silique wall photosynthesis on the metabolites in the funiculus, we also covered the siliques of intact plants with aluminum foil; in these plants, the funiculus and silique wall had lower metabolite levels, compared with control. RNA-sequencing analysis of the funiculi in the dark-treated and light-exposed siliques showed that the expression of genes encoding nutrient transporters significantly increased in the funiculi in the dark-treated siliques. Furthermore, the transcripts encoding primary metabolic enzymes for amino acid synthesis, fatty acid synthesis and triacylglycerol assembly, and sucrose-starch metabolism, were also markedly up-regulated, despite the decline in metabolite levels of funiculi in the dark-treated silique. These results provide new insights into funiculus function in seed growth and synthesis of storage reserves in seeds, at the metabolic and transcriptional levels. The identification of these metabolites and genes also provides useful information for creating genetically enhanced oilseed crops with improved seed properties.

SUBMITTER: Tan H

PROVIDER: S-EPMC5080329 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Nutritional functions of the funiculus in Brassica napus seed maturation revealed by transcriptome and dynamic metabolite profile analyses.

Tan Helin H Xiang Xiaoe X Tang Jie J Wang Xingchun X

Plant molecular biology 20160818 4-5

The funiculus provides the sole channel of communication between the seed and the parent plant; however, little is known about its role in nutrient supply during seed maturation. Here, we investigated the dynamic metabolite profiles of the funiculus during seed maturation in Brassica napus. The funiculus was fully developed at 21 days after flowering (DAF), but the levels of nutrients, including carbohydrates, fatty acids, and amino acids, increased rapidly from 21 to 35 DAF. Orthogonal partial ...[more]

PMID: 27539000

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Project description:BackgroundMicroRNAs (miRNAs) are 20-21 nucleotide RNA molecules that suppress the transcription of target genes and may also inhibit translation. Despite the thousands of miRNAs identified and validated in numerous plant species, only small numbers have been identified from the oilseed crop plant Brassica napus (canola) - especially in seeds.ResultsUsing next-generation sequencing technologies, we performed a comprehensive analysis of miRNAs during seed maturation at 9 time points from 10 days after flowering (DAF) to 50 DAF using whole seeds and included separate analyses of radicle, hypocotyl, cotyledon, embryo, endosperm and seed coat tissues at 4 selected time points. We identified more than 500 conserved miRNA or variant unique sequences with >300 sequence reads and also found 10 novel miRNAs. Only 27 of the conserved miRNA sequences had been previously identified in B. napus (miRBase Release 18). More than 180 MIRNA loci were identified/annotated using the B. rapa genome as a surrogate for the B.napus A genome. Numerous miRNAs were expressed in a stage- or tissue-specific manner suggesting that they have specific functions related to the fine tuning of transcript abundance during seed development. miRNA targets in B. napus were predicted and their expression patterns profiled using microarray analyses. Global correlation analysis of the expression patterns of miRNAs and their targets revealed complex miRNA-target gene regulatory networks during seed development. The miR156 family was the most abundant and the majority of the family members were primarily expressed in the embryo.ConclusionsLarge numbers of miRNAs with diverse expression patterns, multiple-targeting and co-targeting of many miRNAs, and complex relationships between expression of miRNAs and targets were identified in this study. Several key miRNA-target expression patterns were identified and new roles of miRNAs in regulating seed development are suggested. miR156, miR159, miR172, miR167, miR158 and miR166 are the major contributors to the network controlling seed development and maturation through their pivotal roles in plant development. miR156 may regulate the developmental transition to germination.

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 regulator are conserved in B. napus, suggesting a shared regulatory network with other plant 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.

Dataset Information

Nutritional functions of the funiculus in Brassica napus seed maturation revealed by transcriptome and dynamic metabolite profile analyses.

Publications

Nutritional functions of the funiculus in Brassica napus seed maturation revealed by transcriptome and dynamic metabolite profile analyses.

Similar Datasets

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