Metabolic engineering of energycane to hyperaccumulate lipids in vegetative biomass

Abstract

Background The metabolic engineering of high-biomass crops for lipid production in their vegetative biomass has recently been proposed as a strategy to elevate energy density and lipid yields for biodiesel production. Energycane and sugarcane are highly polyploid, interspecific hybrids between Saccharum officinarum and Saccharum spontaneum that differ in the amount of ancestral contribution to their genomes. This results in greater biomass yield and persistence in energycane, which makes it the preferred target crop for biofuel production. Results Here, we report on the hyperaccumulation of triacylglycerol (TAG) in energycane following the overexpression of the lipogenic factors Diacylglycerol acyltransferase1-2 (DGAT1-2) and Oleosin1 (OLE1) in combination with RNAi suppression of SUGAR-DEPENDENT1 (SDP1) and Trigalactosyl diacylglycerol1 (TGD1). TAG accumulated up to 1.52% of leaf dry weight (DW,) a rate that was 30-fold that of non-modified energycane, in addition to almost doubling the total fatty acid content in leaves to 4.42% of its DW. Pearson’s correlation analysis showed that the accumulation of TAG had the highest correlation with the expression level of ZmDGAT1-2, followed by the level of RNAi suppression for SDP1. Conclusions This is the first report on the metabolic engineering of energycane and demonstrates that this resilient, high-biomass crop is an excellent target for the further optimization of the production of lipids from vegetative tissues.

Cell‐type‐specific metabolism in plants

“…However, whilst the spatial characterization of lipids in sink cells, especially in seeds, has been investigated by isolating embryos or using magnetic resonance imaging (MRI) analysis, information on lipid metabolism in isolated source cells is less abundant. The possibility of producing biodiesel from C4 leaves (Luo et al., 2022; Zale et al., 2016) creates a demand to understand the spatial resolution and regulation of lipid metabolism in photosynthetic cells. For instance, histochemical and MS‐based lipidomics analysis have revealed the dynamic of lipid droplet degradation in guard cells and their role in stomatal opening (McLachlan et al., 2016).…”

Triacylglycerol, total fatty acid, and biomass accumulation of metabolically engineered energycane grown under field conditions confirms its potential as feedstock for drop‐in fuel production

“…However, metabolic engineering strategies combining the simultaneous optimization of fatty acid synthesis, TAG assembly and protection from degradation termed "push, pull, protect strategy" resulted in more drastic increases of TAG levels in vegetative tissues (Vanhercke, El Tahchy, et al, 2014). To date, vegetative tissues of both model plants (Fan et al, 2013;Vanhercke et al, 2013;Vanhercke, El Tahchy, et al, 2014;Vanhercke, Petrie, et al, 2014;Yang et al, 2015) and high biomass plants such as sugarcane, energycane, maize, sorghum, potato, duckweed, and perennial ryegrass (Alameldin et al, 2017;Beechey-Gradwell et al, 2020;Cao et al, 2023;Hofvander et al, 2016;Liang et al, 2023;Liu et al, 2017;Luo et al, 2022;Parajuli et al, 2020;Vanhercke et al, 2019;Xu et al, 2012;Zale et al, 2016) have been metabolically engineered for hyperaccumulation of TAG. This involved overexpression of WRI1, DGAT1, and OLE1, and/or suppression of SUGAR-DEPENDENT1 (SDP1) and TRIGA LAC TOS YLD IAC YLG LYCEROL1 (TGD1) or PEROXISOMAL TRANSPORTER1 (PXA1).…”

Microbiome differences in sugarcane and metabolically engineered oilcane accessions and their implications for bioenergy production

“…Breeding efforts to maintain the quality and agronomic performance of elite cultivars have improved sugar yield and quality [8][9][10], disease resistance [11][12][13][14][15], and ratoon ability [16]. Sugarcane has also been modified through transgenic routes, gene editing, and molecular breeding to improve productivity or its potential as a biofuel crop [17][18][19][20][21][22]. Specifically, energycane has been engineered to hyperaccumulate lipids in its vegetative biomass through WRI1 and DGAT 1 gene modification [17][18][19][20].…”

“…Sugarcane has also been modified through transgenic routes, gene editing, and molecular breeding to improve productivity or its potential as a biofuel crop [17][18][19][20][21][22]. Specifically, energycane has been engineered to hyperaccumulate lipids in its vegetative biomass through WRI1 and DGAT 1 gene modification [17][18][19][20]. These efforts have resulted in metabolically engineered oilcane, which hyper-accumulates energy-dense triacylglycerol (TAG) at levels exceeding the non-modified sugarcane by 30-to 400-fold in vegetable tissues [20,21].…”

“…Specifically, energycane has been engineered to hyperaccumulate lipids in its vegetative biomass through WRI1 and DGAT 1 gene modification [17][18][19][20]. These efforts have resulted in metabolically engineered oilcane, which hyper-accumulates energy-dense triacylglycerol (TAG) at levels exceeding the non-modified sugarcane by 30-to 400-fold in vegetable tissues [20,21]. Production of TAGs and other lipids in high biomass crops has been proposed as a strategy to meet the demands for plant lipid and biodiesel production [17,21,22].…”