Transcriptome analyses reveals the dynamic nature of oil accumulation during seed development of Plukenetia volubilis L.

Abstract

Sacha inchi (Plukenetia volubilis L.) is a shrub native to Amazon rainforests that’s of commercial interest as its seeds contain 35–60% edible oil (dry weight). This oil is one of the healthiest vegetable oils due to its high polyunsaturated fatty acid content and favourable ratio of omega-6 to omega-3 fatty acids. De novo transcriptome assembly and comparative analyses were performed on sacha inchi seeds from five stages of seed development in order to identifying genes associated with oil accumulation and fatty acid production. Of 30,189 unigenes that could be annotated in public databases, 20,446 were differentially expressed unigenes. A total of 14 KEGG pathways related to lipid metabolism were found, and 86 unigenes encoding enzymes involved in α-linolenic acid (ALA) biosynthesis were obtained including five unigenes encoding FATA (Unigene0008403), SAD (Unigene0012943), DHLAT (Unigene0014324), α-CT (Unigene0022151) and KAS II (Unigene0024371) that were significantly up-regulated in the final stage of seed development. A total of 66 unigenes encoding key enzymes involved in the synthesis of triacylglycerols (TAGs) were found, along with seven unigenes encoding PDCT (Unigene0000909), LPCAT (Unigene0007846), Oleosin3 (Unigene0010027), PDAT1 (Unigene0016056), GPDH (Unigene0022660), FAD2 (Unigene0037808) and FAD3 (Unigene0044238); these also proved to be up-regulated in the final stage of seed development.

Overexpression of PvFAD3 Gene from Plukenetia volubilis Promotes the Biosynthesis of α-Linolenic Acid in Transgenic Tobacco Seeds

“…To explore the possible molecular mechanism by which PvFAD3 positively regulates the biosynthesis of α-linolenic acid, we investigated the regulating effects of PvFAD3 on the expression levels of two stages of developing seeds (the initial stage, Pv-1 and the fast oil accumulation stage, Pv-2) in P. volubilis. The expression of PvFAD3 was downregulated at Pv-1 and significantly upregulated at Pv-2, consistent with the dynamic change of α-linolenic acid content at various stages of seed development [21], thus further demonstrating the close correlation between PvFAD3 expression and α-linolenic acid accumulation. To further validate the biological function of the PvFAD3, a vector overexpressing the PvFAD3 was constructed and overexpressed in tobacco seeds, which significantly increased the content of α-linolenic acid (2.13%), significantly decreased the content of linoleic acid (6.78%), and obviously increased the oil content (24.22%) and palmitic acid (2.77%).…”

“…In this study, the PvFAD3 gene was obtained by PCR homologous cloning based on the transcriptome data of P. volubilis in our previous studies [ 21 ]. The bioinformatics analysis of PvFAD3 showed that the full-length DNA sequence of PvFAD3 was 1871 bp, including eight exons and seven introns, encoding 379 amino acids, with a molecular weight of 43.53 kDa and an isoelectric point of 7.79.…”

“…Our research team analyzed the transcriptomic data of P. volubilis seeds at various growth stages obtained using second-generation high-throughput sequencing technology and discovered that the PvFAD3 gene in P. volubilis seeds was overexpressed during the rapid period of oil accumulation. [ 21 ]. We presumed that the extremely high expression level of PvFAD3 was closely related to the efficient accumulation of α-linolenic acid, which is consistent with the findings of Wang et al [ 22 , 23 ] on P. volubilis seeds.…”

Integrated Transcriptome and Proteome Analysis Provides Insight into the Ribosome Inactivating Proteins in Plukenetia volubilis Seeds

“…These phytotoxins might become unstable under heat treatment, suggesting that the long-term consumption of large quantities of fresh seeds and leaves of P. volubilis should be avoided [ 18 , 19 ]. In addition, Liu et al [ 20 ] and Wang et al [ 21 ] performed the transcriptome analysis of five and two developmental stages of P. volubilis seeds, respectively. Surprisingly, the amounts of RIPs transcripts were the highest at the maturity stage or the fast oil accumulation stage, and the expression levels of those transcripts were greater than 10 6 .…”

Transcriptional Basis for Haustorium Formation and Host Establishment in Hemiparasitic Psittacanthus schiedeanus Mistletoes

“…Several recent studies have used next-generation RNA sequencing technology (RNA-seq) for many plant species to generate transcriptome information (e.g., Liu et al, 2020 ; Xu et al, 2020 ; Mei et al, 2021 ; Nguyen et al, 2021 ; Pérez-Torres et al, 2021 ). As the transcriptome actively changes depending on factors such as developmental stage and environmental conditions (e.g., Girke et al, 2000 ; Dong et al, 2004 ), researchers can determine when and where genes are turned on or off across types of cells and tissues.…”