Oil Biosynthesis in Underground Oil-Rich Storage Vegetative Tissue: Comparison ofCyperus esculentusTuber with Oil Seeds and Fruits

Abstract

Cyperus esculentus is unique in that it can accumulate rich oil in its tubers. However, the underlying mechanism of tuber oil biosynthesis is still unclear. Our transcriptional analyses of the pathways from pyruvate production up to triacylglycerol (TAG) accumulation in tubers revealed many distinct species-specific lipid expression patterns from oil seeds and fruits, indicating that in C. esculentus tuber: (i) carbon flux from sucrose toward plastid pyruvate could be produced mostly through the cytosolic glycolytic pathway; (ii) acetyl-CoA synthetase might be an important contributor to acetyl-CoA formation for plastid fatty acid biosynthesis; (iii) the expression pattern for stearoyl-ACP desaturase was associated with high oleic acid composition; (iv) it was most likely that endoplasmic reticulum (ER)-associated acyl-CoA synthetase played a significant role in the export of fatty acids between the plastid and ER; (v) lipid phosphate phosphatase (LPP)-δ was most probably related to the formation of the diacylglycerol (DAG) pool in the Kennedy pathway; and (vi) diacylglyceroltransacylase 2 (DGAT2) and phospholipid:diacylglycerolacyltransferase 1 (PDAT1) might play crucial roles in tuber oil biosynthesis. In contrast to oil-rich fruits, there existed many oleosins, caleosins and steroleosins with very high transcripts in tubers. Surprisingly, only a single ortholog of WRINKLED1 (WRI1)-like transcription factor was identified and it was poorly expressed during tuber development. Our study not only provides insights into lipid metabolism in tuber tissues, but also broadens our understanding of TAG synthesis in oil plants. Such knowledge is of significance in exploiting this oil-rich species and manipulating other non-seed tissues to enhance storage oil production.

Sucrose metabolism in developing oil-rich tubers of Cyperus esculentus: comparative transcriptome analysis

“…In this study, we indeed observed the high Suc-to-hexose ratios over the tuber development of C. esculentus (Fig. 1 ), where oil accumulation began at around 50 DAS [ 40 ].…”

“…Our previous transcriptome analyses of C. esculentus tubers from three representative samples at 50, 85 and 120 DAS of developmental stages (i.e. the early stage of 40–50 DAS, the middle stage of 50–85 DAS and the late stage of 85–120 DAS, corresponding to the stage of low oil level and oil accumulation rate, medium oil level but high oil accumulation rate, and high oil level with low oil accumulation rate, respectively) have indicated that 41.05% of total 99,558 transcripts were successfully annotated [ 40 ]. Among them, 488 annotated transcripts were involved in carbohydrate metabolism, of which 355 unigenes were found to be expressed in the developing C. esculentus tubers (Additional file 1 : Table S1d).…”

Systems biology approach identifies functional modules and regulatory hubs related to secondary metabolites accumulation after transition from autotrophic to heterotrophic growth condition in microalgae

“…Further analysis of connectivity in the none-preserved module at the PR phase reveals another gene, LACS7, a part of peroxisome proliferator-activated receptors (PPAR) and Adipocytokine signaling pathways [55], as another important gene. Newly synthesized free fatty acids (FAs) need to activate to acyl-CoA form by LACS to involves in the glycerolipid metabolic pathways, indicating the critical roles of LACS in FA metabolism [56]. In Arabidopsis, a family of nine genes encoding LACS protein has been identified to play their roles in various aspects of lipid metabolism at different subcellular localizations.…”

Review: Omics and Strategic Yield Improvement in Oil Crops

“…Some studies have used comparative proteomics approaches on lipid regulation between different types of oilseeds [14,47]. In a recent study, Yang et al [48] conducted a comprehensive and systematic transcriptome analysis of Cyperus esculentus, along with a comparative analysis of other oil-rich tissues of seeds and mesocarp to understand oil biosynthesis in vegetative tissues of diverse species. Cyperus esculentus is unique in that it can accumulate oil in its tubers.…”

“…However, upon maturation, chlorophyll content continued to increase, but leaf nitrogen decreased dramatically until leaf 32. No significant changes in either chlorophyll and nitrogen content were observed in leaves [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. Following this study, the distribution of natural 13 C in oil palm leaves was investigated.…”