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Fatty acid composition of developing tree peony (Paeonia section Moutan DC.) seeds and transcriptome analysis during seed development.

Li SS, Wang LS, Shu QY, Wu J, Chen LG, Shao S, Yin DD - BMC Genomics (2015)

Bottom Line: Therefore, transcriptome data is needed to better understand the underlying mechanisms.These data lay the foundation for further understanding of molecular mechanism responsible for lipid biosynthesis and the high unsaturated fatty acids (especially ALA) accumulation.Meanwhile, it provides theoretical base for potential oilseed application in the respect of n-6 to n-3 ratio for human diets and future regulation of target healthy components of oils.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources and Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China. shshli@ibcas.ac.cn.

ABSTRACT

Background: Tree peony (Paeonia section Moutan DC.) is known for its excellent ornamental and medicinal values. In 2011, seeds from P. ostii have been identified as novel resource of α-linolenic acid (ALA) for seed oil production and development in China. However, the molecular mechanism on biosynthesis of unsaturated fatty acids in tree peony seeds remains unknown. Therefore, transcriptome data is needed to better understand the underlying mechanisms.

Results: In this study, lipid accumulation contents were measured using GC-MS methods across developing tree peony seeds, which exhibited an extraordinary ALA content (49.3%) in P. ostii mature seeds. Transcriptome analysis was performed using Illumina sequencing platform. A total of 144 million 100-bp paired-end reads were generated from six libraries, which identified 175,874 contigs. In the KEGG Orthology enrichment of differentially expressed genes, lipid metabolism pathways were highly represented categories. Using this data we identified 388 unigenes that may be involved in de novo fatty acid and triacylglycerol biosynthesis. In particular, three unigenes (SAD, FAD2 and FAD8) encoding fatty acid desaturase with high expression levels in the fast oil accumulation stage compared with the initial stage of seed development were identified.

Conclusions: This study provides the first comprehensive genomic resources characterizing tree peony seeds gene expression at the transcriptional level. These data lay the foundation for further understanding of molecular mechanism responsible for lipid biosynthesis and the high unsaturated fatty acids (especially ALA) accumulation. Meanwhile, it provides theoretical base for potential oilseed application in the respect of n-6 to n-3 ratio for human diets and future regulation of target healthy components of oils.

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Related in: MedlinePlus

Observation and measurement of lipids across the developmental period of tree peony seeds. (A) The developmental progress of P. ostii seeds (S1-S10). Pods were harvested at 10 days after pollination (DAP, immature stage), and then every 10 days until 100 DAP (pods containing mature seeds). (B) The five dominant fatty acids at ten time points during tree peony seed development (mean ± SD, n = 3).
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Fig1: Observation and measurement of lipids across the developmental period of tree peony seeds. (A) The developmental progress of P. ostii seeds (S1-S10). Pods were harvested at 10 days after pollination (DAP, immature stage), and then every 10 days until 100 DAP (pods containing mature seeds). (B) The five dominant fatty acids at ten time points during tree peony seed development (mean ± SD, n = 3).

Mentions: Seeds of P. ostii at different developmental stages were harvested and flash frozen. The methodology validated in our previous study was applied to analyze the FA composition by gas chromatography–mass spectrometry at ten developmental stages [8]. As shown in Figure 1, there were five dominant components, namely, α-linolenic acid (C18:3Δ9c, 12c, 15c, 49.3% of total FAs at S9), linoleic acid (C18:2Δ9c, 12c, 26.2%), oleic acid (C18:1Δ9c, 15.6%), palmitic acid (C16:0, 5.8%), and stearic acid (C18:0, 1.6%). The combined content of these five FAs always predominated across the ten developmental stages at high percentages (more than 98.5% of total FA). The other four minor FAs (<1.5%) were also detectable at trace levels including myristic acid (C14:0), cis-11-octadecenoic acid (C18:1Δ11c), eicosanoic acid (C20:0), and cis-11-eicosenoic acid (C20:1Δ11c). Although the FA compositions and contents achieved in this study were not completely identical to the results of previous studies, the identity of the dominant compounds (ALA as dominant and LA as subdominant) and the high proportion of UFAs were consistent [7,8]. Additionally, the presence of γ-linolenic acid (GLA) was reported in the seed kernel and coat of P. rockii [7], while it was not detected in other researches, neither in the present study. We had demonstrated that GLA did not exist in the seeds of 60 tree peony cultivars by co-elution of GLA and ALA mix [8], which was confirmed in this study due to lack of expression information of genes encoding for delta-6 desaturase through transcriptome analysis.Figure 1


Fatty acid composition of developing tree peony (Paeonia section Moutan DC.) seeds and transcriptome analysis during seed development.

Li SS, Wang LS, Shu QY, Wu J, Chen LG, Shao S, Yin DD - BMC Genomics (2015)

Observation and measurement of lipids across the developmental period of tree peony seeds. (A) The developmental progress of P. ostii seeds (S1-S10). Pods were harvested at 10 days after pollination (DAP, immature stage), and then every 10 days until 100 DAP (pods containing mature seeds). (B) The five dominant fatty acids at ten time points during tree peony seed development (mean ± SD, n = 3).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4404109&req=5

Fig1: Observation and measurement of lipids across the developmental period of tree peony seeds. (A) The developmental progress of P. ostii seeds (S1-S10). Pods were harvested at 10 days after pollination (DAP, immature stage), and then every 10 days until 100 DAP (pods containing mature seeds). (B) The five dominant fatty acids at ten time points during tree peony seed development (mean ± SD, n = 3).
Mentions: Seeds of P. ostii at different developmental stages were harvested and flash frozen. The methodology validated in our previous study was applied to analyze the FA composition by gas chromatography–mass spectrometry at ten developmental stages [8]. As shown in Figure 1, there were five dominant components, namely, α-linolenic acid (C18:3Δ9c, 12c, 15c, 49.3% of total FAs at S9), linoleic acid (C18:2Δ9c, 12c, 26.2%), oleic acid (C18:1Δ9c, 15.6%), palmitic acid (C16:0, 5.8%), and stearic acid (C18:0, 1.6%). The combined content of these five FAs always predominated across the ten developmental stages at high percentages (more than 98.5% of total FA). The other four minor FAs (<1.5%) were also detectable at trace levels including myristic acid (C14:0), cis-11-octadecenoic acid (C18:1Δ11c), eicosanoic acid (C20:0), and cis-11-eicosenoic acid (C20:1Δ11c). Although the FA compositions and contents achieved in this study were not completely identical to the results of previous studies, the identity of the dominant compounds (ALA as dominant and LA as subdominant) and the high proportion of UFAs were consistent [7,8]. Additionally, the presence of γ-linolenic acid (GLA) was reported in the seed kernel and coat of P. rockii [7], while it was not detected in other researches, neither in the present study. We had demonstrated that GLA did not exist in the seeds of 60 tree peony cultivars by co-elution of GLA and ALA mix [8], which was confirmed in this study due to lack of expression information of genes encoding for delta-6 desaturase through transcriptome analysis.Figure 1

Bottom Line: Therefore, transcriptome data is needed to better understand the underlying mechanisms.These data lay the foundation for further understanding of molecular mechanism responsible for lipid biosynthesis and the high unsaturated fatty acids (especially ALA) accumulation.Meanwhile, it provides theoretical base for potential oilseed application in the respect of n-6 to n-3 ratio for human diets and future regulation of target healthy components of oils.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Plant Resources and Beijing Botanical Garden, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China. shshli@ibcas.ac.cn.

ABSTRACT

Background: Tree peony (Paeonia section Moutan DC.) is known for its excellent ornamental and medicinal values. In 2011, seeds from P. ostii have been identified as novel resource of α-linolenic acid (ALA) for seed oil production and development in China. However, the molecular mechanism on biosynthesis of unsaturated fatty acids in tree peony seeds remains unknown. Therefore, transcriptome data is needed to better understand the underlying mechanisms.

Results: In this study, lipid accumulation contents were measured using GC-MS methods across developing tree peony seeds, which exhibited an extraordinary ALA content (49.3%) in P. ostii mature seeds. Transcriptome analysis was performed using Illumina sequencing platform. A total of 144 million 100-bp paired-end reads were generated from six libraries, which identified 175,874 contigs. In the KEGG Orthology enrichment of differentially expressed genes, lipid metabolism pathways were highly represented categories. Using this data we identified 388 unigenes that may be involved in de novo fatty acid and triacylglycerol biosynthesis. In particular, three unigenes (SAD, FAD2 and FAD8) encoding fatty acid desaturase with high expression levels in the fast oil accumulation stage compared with the initial stage of seed development were identified.

Conclusions: This study provides the first comprehensive genomic resources characterizing tree peony seeds gene expression at the transcriptional level. These data lay the foundation for further understanding of molecular mechanism responsible for lipid biosynthesis and the high unsaturated fatty acids (especially ALA) accumulation. Meanwhile, it provides theoretical base for potential oilseed application in the respect of n-6 to n-3 ratio for human diets and future regulation of target healthy components of oils.

Show MeSH
Related in: MedlinePlus