Abstract
BackgroundPaeonia lactiflora ‘Hangshao’ is widely cultivated in China as a traditional Chinese medicine ‘Radix Paeoniae Alba’. Due to the abundant unsaturated fatty acids in its seed, it can also be regarded as a new oilseed plant. However, the process of the biosynthesis of unsaturated fatty acids in it has remained unknown. Therefore, transcriptome analysis is helpful to better understand the underlying molecular mechanisms.ResultsFive main fatty acids were detected, including stearic acid, palmitic acid, oleic acid, linoleic acid and α-linolenic acid, and their absolute contents first increased and then decreased during seed development. A total of 150,156 unigenes were obtained by transcriptome sequencing. There were 15,005 unigenes annotated in the seven functional databases, including NR, NT, GO, KOG, KEGG, Swiss-Prot and InterPro. Based on the KEGG database, 1766 unigenes were annotated in the lipid metabolism. There were 4635, 12,304, and 18,291 DEGs in Group I (60 vs 30 DAF), Group II (90 vs 60 DAF) and Group III (90 vs 30 DAF), respectively. A total of 1480 DEGs were detected in the intersection of the three groups. In 14 KEGG pathways of lipid metabolism, 503 DEGs were found, belonging to 111 enzymes. We screened out 123 DEGs involved in fatty acid biosynthesis (39 DEGs), fatty acid elongation (33 DEGs), biosynthesis of unsaturated fatty acid (24 DEGs), TAG assembly (17 DEGs) and lipid storage (10 DEGs). Furthermore, qRT-PCR was used to analyze the expression patterns of 16 genes, including BBCP, BC, MCAT, KASIII, KASII, FATA, FATB, KCR, SAD, FAD2, FAD3, FAD7, GPAT, DGAT, OLE and CLO, most of which showed the highest expression at 45 DAF, except for DGAT, OLE and CLO, which showed the highest expression at 75 DAF.ConclusionsWe predicted that MCAT, KASIII, FATA, SAD, FAD2, FAD3, DGAT and OLE were the key genes in the unsaturated fatty acid biosynthesis and oil accumulation in herbaceous peony seed. This study provides the first comprehensive genomic resources characterizing herbaceous peony seed gene expression at the transcriptional level. These data lay the foundation for elucidating the molecular mechanisms of fatty acid biosynthesis and oil accumulation for herbaceous peony.
Highlights
Paeonia lactiflora ‘Hangshao’ is widely cultivated in China as a traditional Chinese medicine ‘Radix Paeoniae Alba’
We predicted that MCAT, 3-oxoacyl-ACP synthase III (KASIII), Fatty acyl-ACP thioesterase A (FATA), stearoyl-ACP desaturase (SAD), FAD2, FAD3, diacylglycerol acyltransferase (DGAT) and OLE were the key genes in the unsaturated fatty acid biosynthesis and oil accumulation in herbaceous peony seed
We identified 6 Differentially expressed gene (DEG) annotated to OLE, the FPKM values of which in the transcriptome were very high and increasing; the expression of OLE by quantitative real-time polymerase chain reaction (qRT-PCR) was highest at 75 days after flowering (DAF), which was consistent with the oil accumulation
Summary
Paeonia lactiflora ‘Hangshao’ is widely cultivated in China as a traditional Chinese medicine ‘Radix Paeoniae Alba’. As a well-known Chinese traditional flower, herbaceous peony (Paeonia lactiflora Pall.) was cultivated more than 4000 years. Herbaceous peony is cultivated as a medicinal and ornamental plant in China. As an important medicinal plant, herbaceous peony ‘Hangshao’, the root of which is the traditional Chinese medicine ‘Radix Paeoniae Alba’, is mainly cultivated in Zhejiang Province and widely cultivated in China [9]. It has a single lobe and a higher seed-setting rate. Herbaceous peony ‘Hangshao’ has the potential to be cultivated as a multifunctional plant, as an ornamental, medicinal plant and as an edible oil resource
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