Identifying transcription factors that reduce wood recalcitrance and improve enzymatic degradation of xylem cell wall in Populus

Abstract

Developing an efficient deconstruction step of woody biomass for biorefinery has been drawing considerable attention since its xylem cell walls display highly recalcitrance nature. Here, we explored transcriptional factors (TFs) that reduce wood recalcitrance and improve saccharification efficiency in Populus species. First, 33 TF genes up-regulated during poplar wood formation were selected as potential regulators of xylem cell wall structure. The transgenic hybrid aspens (Populus tremula × Populus tremuloides) overexpressing each selected TF gene were screened for in vitro enzymatic saccharification. Of these, four transgenic seedlings overexpressing previously uncharacterized TF genes increased total glucan hydrolysis on average compared to control. The best performing lines overexpressing Pt × tERF123 and Pt × tZHD14 were further grown to form mature xylem in the greenhouse. Notably, the xylem cell walls exhibited significantly increased total xylan hydrolysis as well as initial hydrolysis rates of glucan. The increased saccharification of Pt × tERF123-overexpressing lines could reflect the improved balance of cell wall components, i.e., high cellulose and low xylan and lignin content, which could be caused by upregulation of cellulose synthase genes upon the expression of Pt × tERF123. Overall, we successfully identified Pt × tERF123 and Pt × tZHD14 as effective targets for reducing cell wall recalcitrance and improving the enzymatic degradation of woody plant biomass.

CRISPR/Cas9‐mediated P‐CR domain‐specific engineering of CESA4 heterodimerization capacity alters cell wall architecture and improves saccharification efficiency in poplar

“…The lignocellulose composition, high cellulose DP and CrI could increase the biomass recalcitrance and hinder saccharification efficiency (De Meester et al ., 2020 ; Himmel et al ., 2007 ; Hori et al ., 2020 ; Hu et al ., 2018 a; Hu et al ., 2018 b; Jang et al ., 2021 ; Martarello et al ., 2021 ; Speicher et al ., 2018 ). Here, the saccharification potential of WT and three T0 mutant plants were further investigated based on cellulose‐to‐glucose conversion efficiency under the limited saccharification conditions, including acidic (1 M of HCl, 80 °C, 2 h), alkaline (62.5 m m of NaOH, 90 °C, 3 h), and no pretreatment.…”

“…However, lignocellulose recalcitrance is a major challenge in cellulose‐based industries that hinders the saccharification yield. To overcome this limitation, metabolic engineering and genetic manipulation of genes involved in SCW biosynthesis and lignocellulosic compounds in woody plants are the most magnificent fields that have been reported so far (Cao et al ., 2020 ; De Meester et al ., 2020 ; Himmel et al ., 2007 ; Hori et al ., 2020 ; Hu, et al ., 2018 ; Hu, et al ., 2018 ; Huang et al ., 2019 ). Among woody plants, poplar ( Populus sp.)…”

Overexpression of Plasma Membrane H+-ATPase in Guard Cells Enhances Light-Induced Stomatal Opening, Photosynthesis, and Plant Growth in Hybrid Aspen

“…Tissue-specific gene expression patterns of 13 Populus PM H + -ATPase genes were examined by re-analysing the RNA sequencing data (Shi et al, 2017). We normalised the raw count data set obtained by RNA sequencing (GSE81077) for xylem, phloem, leaf, shoot, and root with trimmed mean M-values using edgeR v. 3.18.1 (Robinson et al, 2010) in R software v. 3.3.2 (R Core Team, 2018Hori et al, 2020).…”

Mitigating biomass recalcitrance for plant‐based bioenergy production

“…Exploring novel approaches for digesting plant biomass requires a considerable understanding of these factors. Genetic transformation of plants can influence the biosynthesis of lignocellulosic polymers and can play a key role in reducing biomass recalcitrance 56–60 . The following sections detail the chemistry involved in cellulose recalcitrance, the structures, depicted synthetic routes of lignocellulosic polymers, and genetic transformation strategies that influence biomass composition.…”