| In our previous report,total six genes(GH9A1,GH9B6,GH10-4,GT61-3,GT61-4,GT61-11)have been proposed to involve in plant cell wall ’groove structure’ formation and modification.In particular,GH9A1 and GH9B6 are respectively involved in cellulose biosynthesis and post-modification,whereas GT61-3,GT61-4,GT61-11 and GH10-4 are associated with hemciellulsoe formation and modification.To explore those gene functions,this study first identified their upstream promoter sequences,and then observed the related GUS expression patterns using those promoters.Finally,the relevant bioinformatics analysiswas performed to verify those promoters.The main results were described below.1.The promoter sequences of six genes were cloned and their sequence lengths are 2050bp,1971 bp,2271bp,2323bp,2455bp,1567bp,respectively.2.The expression patterns of six genes were observed in rice whole life cycles using public database.As a comparison,GH9A1 and GH9B6 exhibit a similar expression pattern,whereas GH10-4 expresses at low level in whole life cycle of rice.Notably,GT61-3 has a constitutive expression,GT61-4 is highly expressed in callus tissue,embryos,radicle,spike,root,stamens,and GT61-11 is mainly expressed in leaves and young stem tissues.3.Based on GUS staining,GH9A1 and GH9B6 are obviously expressed in rice leaf,husk,the first and third internodes of stem(from top to bottom),GH10-4 has a weak expression in the third internode of stem,and GT61-3 is mainly expressed in the leaf or in the first,second and third internodes of stem.In addition,GT61-4 mainly expressed in the leaf veins and primary phloem of the third section of stem,whereas GT61-11 mainly expressed in the leaf veins and primary phloem of third internode of stem.Hence,the GUS staining has indicated six gene distinct expression patterns,which are consistent with the bioinformatics analysis.4.MYBPLANT element related to vascular specific expression and mannose-related POLLEN1LELAT52 element,and storage protein associated SEF4MOTIFGM7S and CGACGOSAMY3 elementare further identified by analyzing cis-acting elements in the promoter sequences.Common reed(Phragmitesaustralis)is one of the most widespread wetland plants with high biomass yield for biofuel purpose.As an initial step for biomass process towards bioethanol production,various distinct physical and chemical pretreatmentswere performedfor wall polymer disassociation in this study.The main results were described below.1.In this study,three major wall polymers(cellulose,hemicelluloses and lignin)levels were initially determined at 35%,26%and 21%in the mature stem tissues(raw materials)of reed.Steam explosion was then performed with the raw materials,leading to hemicelluloses and lignin extractions by 76%and 41%,respectively.2.The steam explosion significantly altered wall polymers features.Cellulose CrI value was increased by 13%,whereas cellulose DP was reduced by 45%in the steam-exploded residues.In addition,the steam explosion caused a high percentage of glucose(Glu)extraction with relatively reduced Xyl and Ara proportions.Three monomers proportions of lignin were not much altered in the steam-exploded residues.3.As a comparison,the raw materials under various pretreatments,exhibited the hexoses yields at 9.94%(control),34.68%(2%H2SO4),83.89%(8%NaOH),43.41%(10%CaO),37.13%(8minLHW),whereasthe steam-exploded residues exhibited the hexoses yields at 52.11%(control),75.9%(0.5%H2SO4),88.31%(4%NaOH),70.32%(5%CaO),66.83%(2minLHW).Thereby,the physical(steam-explosion)and chemical pretreatments performed in this study could cause a distinctive enhancement on biomass enzymatic saccharification in reed,but the steam explosion combined with other pretreatments(such as NaOH,H2SO4,CaO,LHW)could enhance hexoses yields released from enzymatic hydrolysisin different degrees.4.Furthermore,the 1%Tween-80 supplement is extremely effective for enhancing biomass enzymatic saccharification of steam-exploded residues. |
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