Plant cell wall represents an enormous biomass resource,but its recalcitrance principally decides a costly biomass process for biofuels and chemical production.Hence,selection of bioenergy crops has been considered as a promising solution by genetic modification of plant cell wall composition and structure.Here,we identified the key factors of plant cell walls on biomass enzymatic saccharification under various physical and chemical pretreatments using systems biology approach that bases on a correlative and integrative analysis among large populations of natural germplasms of Miscanthus and sweet sorghum and genetic mutants of rice,wheat and corn.As a result,lignocellulose crystallinity was examined as the negative factor whereas arabinose substitution degree of xylans was the positive factor on biomass digestibility in all plants tested,suggesting that both factors may determine a fundamental cell wall structure in plants.Using atomic force microscopy,a groove structure of plant cell walls was observed in all five species,and three types of distinct candidate genes were identified that may involve in structure formation and modification.Therefore,a novel model was proposed for genetic modification of plant cell walls towards bioenergy crops selection.