Functional Analysis Of Cellulose Synthase Complexes In Cotton Fibers And Identification Of Lignocellulose Key Factors That Affect Biomass Digestibility In Plants

Lignocellulose-based biofuels are increasingly considered as the desire renewable bioenergy for partial replacement of fossil fuels.Due to lignocellulose recalcitrance,however,biomass conversion is unacceptably costly for biofuel production.Hence,this thesis contains three major research projects: cellulose biosynthesis in cotton fibers,lignocellulose enzymatic digestibility in grass plants,and cellulase productivity from fungi,as described below:1.Among all Gh CESAs proteins identified,CESA1,CESA2,CESA7,and CESA8 are characterized as the major isoforms involved in cellulose biosynthesis of secondary cell walls in cotton.Based on the integrative analyses in both Gossypium hirsutum(G.hirsutum)and Gossypium barbadense(G.barbadense)species including CESA gene expression patterns,CESAs protein levels,and cellulose productions in vivo,CESA8 is demonstrated as an enhancer specific for a rapid and massive cellulose production in cotton fibers.Meanwhile,relatively higher cellulose and callose biosynthesis activities in vitro are determined by adding commercial cellulase during the cotton fiber extraction process.As a consequence,a powerful approach has been established for functional identification of the components that are associated with cellulose and callose synthases complexes by performing a proteomic profiling of the cellulase-aid-extracted proteins in cotton fibers.2.Using a large population of Erianthus arundinaceus samples,a systems biology analysis was performed in this study.As a result,effective extraction of H-monomer(?-hydroxyphenyl monomer)in lignin could positively affect biomass enzymatic saccharification under various physical and chemical pretreatments,whereas effective hemicellulose extraction plays a negative role in determining biomass enzymatic saccharification by increasing the cellulose Cr I(crystallinity Index).3.Total 30 representative Miscanthus straws as substrates were applied to incubate with Rut-C30,a commonly used Trichoderma ressei strain.Correlative analysis indicates that the lignocellulose features of Miscanthus straws laregely affect cellulases production released from Rut-C30.By comparison,the crystalline cellulose and H-monomer(?-hydroxyphenyl monomer)of lignin in Miscanthus straws are the negative factors that affect cellulases production,whereas the non-KOH-extractable hemicellulosic arabinose and arabinose substitution degree in xylan(Arabinose/Xylose)play positive roles.