Silencing of a BAHD acyltransferase in sugarcane increases biomass digestibility

Abstract

Background Sugarcane ( Saccharum spp.) covers vast areas of land (around 25 million ha worldwide), and its processing is already linked into infrastructure for producing bioethanol in many countries. This makes it an ideal candidate for improving composition of its residues (mostly cell walls), making them more suitable for cellulosic ethanol production. In this paper, we report an approach to improving saccharification of sugarcane straw by RNAi silencing of the recently discovered BAHD01 gene responsible for feruloylation of grass cell walls. Results We identified six BAHD genes in the sugarcane genome (Sac BAHD s) and generated five lines with substantially decreased SacBAHD01 expression. To find optimal conditions for determining saccharification of sugarcane straw, we tried multiple combinations of solvent and temperature pretreatment conditions, devising a predictive model for finding their effects on glucose release. Under optimal conditions, demonstrated by Organosolv pretreatment using 30% ethanol for 240 min, transgenic lines showed increases in saccharification efficiency of up to 24%. The three lines with improved saccharification efficiency had lower cell-wall ferulate content but unchanged monosaccharide and lignin compositions. Conclusions The silencing of SacBAHD01 gene and subsequent decrease of cell-wall ferulate contents indicate a promising novel biotechnological approach for improving the suitability of sugarcane residues for cellulosic ethanol production. In addition, the Organosolv pretreatment of the genetically modified biomass and the optimal conditions for the enzymatic hydrolysis presented here might be incorporated in the sugarcane industry for bioethanol production. Electronic supplementary material The online version of this article (10.1186/s13068-019-1450-7) contains supplementary material, which is available to authorized users.

Suppression of a BAHD acyltransferase decreases p‐coumaroyl on arabinoxylan and improves biomass digestibility in the model grass Setaria viridis

“…Recent studies highlight that lowering p CA and FA in grass cell walls leads to a decrease in biomass recalcitrance and thereby an increase in biomass digestibility (Li et al ., 2018; de Souza et al ., 2019). Thus, decreasing p CA or FA contents of grass biomass is a promising strategy for increasing digestibility for biofuel production or animal feeding (Oliveira et al ., 2019b).…”

“…These results suggest that SvBAHD01 is a feruloyl transferase responsible for the addition of FA onto Ara f residues linked to AXs. Furthermore, we recently showed that silencing of SvBAHD01 ortholog in sugarcane ( SacBAHD01 ) led to similar results to those demonstrated in S. viridis (de Souza et al ., 2019). We were interested in characterizing the other BAHD gene in S. viridis and, for that, we selected SvBAHD05 , the ortholog of BdAT1 that appears to act in the addition of FA to AX in Brachypodium distachyon (Buanafina et al ., 2016).…”

Genome-wide comparative analysis of the BAHD superfamily in seven Rosaceae species and expression analysis in pear (Pyrus☓ bretschneideri)

“…The BAHD superfamily has members in various ester synthetic pathways. The functions of several BAHD genes have been reported [43][44][45]. Here, by detecting their HXXXD and DFGWG motifs using a HMMER search, we identified 717 BAHD genes from seven Rosaceae species.…”

Grass secondary cell walls, Brachypodium distachyon as a model for discovery

“…Overexpression of BdBAHD05 (also called BdAT1) caused a moderate increase in FA content and downregulation showed a moderate decrease (Buanafina et al, 2016;de Souza et al, 2018). Analysis in sugarcane revealed six BAHD genes, one of which is homologous to SvBAHD01, and downregulation of SacBAHD01 similarly reduced stem FA content and increased biomass digestibility (de Souza et al, 2019).…”