High oil accumulation in tuber of yellow nutsedge compared to purple nutsedge is associated with more abundant expression of genes involved in fatty acid synthesis and triacylglycerol storage

Abstract

Background Yellow nutsedge is a unique plant species that can accumulate up to 35% oil of tuber dry weight, perhaps the highest level observed in the tuber tissues of plant kingdom. To gain insight into the molecular mechanism that leads to high oil accumulation in yellow nutsedge, gene expression profiles of oil production pathways involved carbon metabolism, fatty acid synthesis, triacylglycerol synthesis, and triacylglycerol storage during tuber development were compared with purple nutsedge, the closest relative of yellow nutsedge that is poor in oil accumulation. Results Compared with purple nutsedge, high oil accumulation in yellow nutsedge was associated with significant up-regulation of specific key enzymes of plastidial RubisCO bypass as well as malate and pyruvate metabolism, almost all fatty acid synthesis enzymes, and seed-like oil-body proteins. However, overall transcripts for carbon metabolism toward carbon precursor for fatty acid synthesis were comparable and for triacylglycerol synthesis were similar in both species. Two seed-like master transcription factors ABI3 and WRI1 were found to display similar transcript patterns but were expressed at 6.5- and 14.3-fold higher levels in yellow nutsedge than in purple nutsedge, respectively. A weighted gene co-expression network analysis revealed that ABI3 was in strong transcriptional coordination with WRI1 and other key oil-related genes. Conclusions These results implied that pyruvate availability and fatty acid synthesis in plastid, along with triacylglycerol storage in oil bodies, rather than triacylglycerol synthesis in endoplasmic reticulum, are the major factors responsible for high oil production in tuber of yellow nutsedge, and ABI3 most likely plays a critical role in regulating oil accumulation. This study is of significance with regard to understanding the molecular mechanism controlling carbon partitioning toward oil production in oil-rich tuber and provides a valuable reference for enhancing oil accumulation in non-seed tissues of crops through genetic breeding or metabolic engineering.

Tiger nut (Cyperus esculentus L.) oil: A review of bioactive compounds, extraction technologies, potential hazards and applications

“…Polycyclic aromatic hydrocarbons (PAHs) are the organic compounds that contain more than one fused aromatic ring, which were mainly formed by the insufficient combustion of some organic substances, such as protein, carbohydrate and lipid ( Ji et al, 2020 ). Currently, there are more than 10,000 types of PAHs found in the natural environment.…”

RNA-Seq Reveals That Multiple Pathways Are Involved in Tuber Expansion in Tiger Nuts (Cyperus esculentus L.)

“…The tubers of the tiger nut not only contain a large amount of starch, oil, and carbohydrate, but also contain dietary fiber, vitamin C, vitamin E, flavonoids, and minerals [15]. Tiger nut oil is rich in unsaturated fatty acids, including oleic acid (64-68%), which have beneficial effects in patients with diabetes, cardiovascular disease, or obesity [16]. In recent years, several studies have used global transcriptome analysis to focus on the metabolism of sugars and the accumulation of reserve oil and starch in developing tiger nut tubers [17].…”