Characterization Of MYB Transcription Factors Regulation On Cell Wall Biosynthesis And Identification Of Cell Wall Factors On Lignocellulose Digestibility In Rice

Rice is an important food crop with a large amount of biomass straws for biofuels.Plant cell wall is mainly composed of cellulose,hemicellulose and lignin.It plays a central role in plant growth and development including cell shape and size,mechanical strength,signal transduction and stress responses.As plant cell wall has a complex network structure,it makes biomass processing costly and results in with secondary pollution due to its recalcitrance.Genetic modification of plant cell wall structure has been considered a feasible approach to reduce biomass recalcitrance.However,cell wall modification may affect plant normal growth and development.In this study,a desired mutant was identified from a rice T-DNA mutant library.The key factors of cell wall affecting biomass enzymatic digestibility were identified by systems biological analysis of many cell wall mutants.The main results were described below:1.Osfc9 gene was identified as a R2R3-MYB transcription factor regulating the formation of secondary cell wall.The Osfc9 mutant was observed with fragile leaves and culms,but rolling leaves and abnormal pollen were found in the over-expression transgenic plant.The hexoses yield of Osfc9 mutant from enzymatic hydrolysis after pretreatment with NaOH or H2SO4 was higher than that of its wild type.2.Diverse cell wall compositions and features were detected in the 29 rice cell wall mutants.Varied biomass enzymatic digestibility was observed in the mutants after pretreatments with NaOH and H2SO4.Based on the systems biological analysis,the biomass enzymatic digestibility was found to be negatively affected by cellulose crystallinity(CrI)and,but positively affected by arabinose substitution degree(Ara/Xyl)and lignin monomer ratio(H/G).