High‐level hemicellulosic arabinose predominately affects lignocellulose crystallinity for genetically enhancing both plant lodging resistance and biomass enzymatic digestibility in rice mutants

Abstract

These two authors contributed equally to this work.Keywords: rice, biomass digestibility, lodging resistance, cell wall, genetic modification, GH9B and XAT. SummaryRice is a major food crop with enormous biomass residue for biofuels. As plant cell wall recalcitrance basically decides a costly biomass process, genetic modification of plant cell walls has been regarded as a promising solution. However, due to structural complexity and functional diversity of plant cell walls, it becomes essential to identify the key factors of cell wall modifications that could not much alter plant growth, but cause an enhancement in biomass enzymatic digestibility. To address this issue, we performed systems biology analyses of a total of 36 distinct cell wall mutants of rice. As a result, cellulose crystallinity (CrI) was examined to be the key factor that negatively determines either the biomass enzymatic saccharification upon various chemical pretreatments or the plant lodging resistance, an integrated agronomic trait in plant growth and grain production. Notably, hemicellulosic arabinose (Ara) was detected to be the major factor that negatively affects cellulose CrI probably through its interlinking with b-1,4-glucans. In addition, lignin and G monomer also exhibited the positive impact on biomass digestion and lodging resistance. Further characterization of two elite mutants, Osfc17 and Osfc30, showing normal plant growth and high biomass enzymatic digestion in situ and in vitro, revealed the multiple GH9B candidate genes for reducing cellulose CrI and XAT genes for increasing hemicellulosic Ara level. Hence, the results have suggested the potential cell wall modifications for enhancing both biomass enzymatic digestibility and plant lodging resistance by synchronically overexpressing GH9B and XAT genes in rice.

Silica distinctively affects cell wall features and lignocellulosic saccharification with large enhancement on biomass production in rice

“…Although silica is a reported plant cell wall component [22][23][24]48], little is known about its effects on cell wall networks. Systems biology analysis based on correlations of large sample populations is a powerful approach to address these issues [44,45]. In this study, we have observed a significant positive correlation between silica and three major wall polymers (cellulose, hemicelluloses and lignin) using 42 distinct cell wall mutants.…”

“…However, in most cases, genetic manipulation could simply cause plant growth defects, and in particular, plant cell wall modification could largely affect plant morphogenesis and related agronomic traits due to the complexity of cell wall structures and the diversity of biological functions [4,47]. Selection of cell wall mutants is thus considered as a powerful approach because it is based on normal-phenotype screening [45]. For instance, we have selected mutants with normal plant growth and development similar to wild type (a classic cultivar), such as Osch11 and Osch12 mutants (Fig.…”

Shading Contributes to the Reduction of Stem Mechanical Strength by Decreasing Cell Wall Synthesis in Japonica Rice (Oryza sativa L.)

“…However, these investigations did not provide explanations of the mechanisms underlying those results in rice for shading between structural carbohydrates and lodging resistance. OsCesA1, OsCesA3 , and OsCesA8 ; and OsCesA4, OsCesA7 , and OsCesA9 genes are the major genes that are responsible for cellulose biosynthesis in the primary cell walls (Tanaka et al, 2003; Wang et al, 2010; Li et al, 2014) and secondary cell walls (Tanaka et al, 2003; Wang et al, 2010; Kotake et al, 2011; Li et al, 2014) of rice stems, respectively. Primary cell walls experience inward thickening formed by secondary cell walls.…”

Ammonium oxalate-extractable uronic acids positively affect biomass enzymatic digestibility by reducing lignocellulose crystallinity in Miscanthus

“…Correlative analysis has been well applied into accounting for three major wall polymers effects on biomass saccharification in Miscanthus and other plants (Xu et al, 2012;Zhang et al, 2013;Li et al, 2013Li et al, , 2014Wu et al, 2013;Jia et al, 2014). Using 179 Miscanthus samples, correlative analysis was performed among AO-extractable components and biomass digestibility upon 1% (v/v) H 2 SO 4 or 1% (w/v) NaOH pretreatment (Fig.…”