Based on systems biology analyses of total 179 representative Miscanthus accessions, ammonium oxalate (AO)-extractable uronic acids could either positively affect biomass digestibility or negatively alter lignocellulose crystallinity at p < 0.01 or 0.05. Comparative analysis of four typical pairs of Miscanthus samples indicated that the AO-extractable uronic acids, other than hexoses and pentoses, play a predominant role in biomass enzymatic saccharification upon various chemical pretreatments, consistent with observations of strong cell tissue destruction in situ and rough biomass residue surface in vitro in the unique Msa24 sample rich in uronic acids. Notably, AO-extraction of uronic acids could significantly increase lignocellulose CrI at p < 0.05, indicating that uronic acids-rich polymers may have the interactions with beta-1,4-glucan chains that reduce cellulose crystallinity. It has also suggested that increasing of uronic acids should be a useful approach for enhancing biomass enzymatic digestibility in Miscanthus and beyond. (C) 2015 Elsevier Ltd. All rights reserved.