Gene Expression Profile Of BpNAC012 Regulating Xylem Development

The NAC transcription factor is one of the largest families of transcription factors in plants,and its distribution ranges from moss plants to higher dicotyledonous plants.Studies have shown that NAC transcription factors have many functions,such as participating in plant growth,cell division and plant senescence,hormone regulation and signal transduction,mineral element nutrition and crop quality improvement.Participate in plant defense response to biological stress and play a role in abiotic stress.In order to study whether the BpNAC012 gene regulates the xylem development and the synthesis of secondary cell wall of Betula platyphylla.the stem of BpNAC012 overexpression,wild-type and suppressive expression was analyzed by anatomical sections to observe the formation of secondary cell wall.The results showed that the degree of xylem development of three month old BpNAC012 overexpression B.platyphylla was higher than that of control,and the xylem development of inhibited expression line was lower than that of control,indicating that BpNAC012 played a role in regulating the xylem development in B.platyphylla.Determination of lignin,hemicellulose and cellulose content in transgenic white birch and wild type white birch.The results showed that when the wild type birch was used as control,the content of cellulose increased in the overexpression lines and decreased in the suppressive expression lines.The results showed that the BpNAC012 gene could regulate the synthesis of the secondary cell wall.In order to further study the molecular regulation mechanism of BpNAC012 regulating the xylem development and secondary cell wall synthesis of birch,the expression profiling was established using high-throughput sequencing technique,and the digital expression profiles of the trans genetic lines and wild-type controls.The results of expression profile analysis showed that 178983 single genes were obtained from the three transcriptional groups.The most annotated genes of GO are the cellular program,metabolism,cellular part,binding and catalytic activity.Carbohydrate metabolism is the most important pathway involved in gene metabolism.Compared with the control,there were 627 up-regulated genes,229 down-regulated genes,299 up-regulated genes and 207 down-regulated genes in OE.A total of 140 genes were differentially expressed in the two transcriptional groups.The expression patterns of differentially expressed genes can be divided into six categories,including up-regulation in over-expression and down-regulation in inhibition of expression.The expression patterns were down-regulated in over-expression lines,up-regulated in inhibition lines,and up-regulated or down-regulated in over-expression and suppressive expression lines.Overexpression of BpNAC012 can regulate more changes in gene expression.The inhibition of BpNAC012 expression is more likely to affect protein modification and transporter gene expression changes.In differentially expressed genes,genes involved in receptor signaling pathway,nutritional metabolism,amino acid synthesis,and phenylpropane biosynthesis related metabolic pathway are relatively enriched.The expression of BpNAC012 can regulate cellulose,lignin synthesis and the expression of genes related to xylem development.Some genes related to cellulose synthesis,such as cellulose synthase-like protein E6 isoform X1 cellulose synthase A catalytic subunit 5,were identified in BpNAC012 overexpression lines.Some cell wall synthase related enzymes such as Xyloglucan endotransglucosylase/hydrolase family protei,Fructose-1,6-bisphosphatase,glucan endo-1,3-beta-glucosidase 14-like probable beta-1,3-galactosyltransferase 19 fasciclin-like ara Binogalactan protein 2 et al.At the same time,some genes related to lignin synthesis and deposition,such as p-coumaryl-CoA 3-hydroxylasephenylalanine-tRNA ligase alpha subunit,peroxidase,were identified.In addition,some genes related to xylern development,such as wall-associated receptor kinase and Leucine-rich repeat protein kinase family protein,were identified.These genes may be induced by BpNAC012 and participate in the xylem development and secondary cell wall synthesis of transgenic birch.Some genes related to xylem development and cell wall synthesis were identified as down-regulated expression,such as those related to cellulosic synthesis,cell wall synthesis and xylem development,such as Cellulose synthase like G3.Endo-1,4-beta-glucanase 1 UTP-glucose-1-phosphate uridylyltransferase,UDP-glucoronosyl/UDP-glucosyl trans Ferase family protein,non-specific lipid-transfer protein-like protein,pectinesterase 29,extensin-like,laccase-7 et al.The down-regulation of these genes may be related to stunted xylem growth and blocked cellulose synthesis in the transgenic line of birch.The expression of BpNAC012 can regulate the expression of many transcription factors at the same time.Including AP2-EREBP,Tify WRKY,Orphans,bHLH,NAC,GRAS,C2H2,SWI/SNF,SET,MYB,HSF,AUX/IAA,ARF,Sigma70-like,m TERF,G2-like,C3H,HB,FAR1,CPP,ABI3VP1,TRAF,GNAT,C2C2-Dof and LOB and so on.The results showed that there were many levels of transcriptional regulation in transgenic lines regulated by BpNAC012,and BpNAC012 could regulate the expression of other transcription factors.There are different regulatory patterns in overexpression and suppression lines,and some specific transcription factors play a corresponding role in the changes of their characters.On this basis,the differentially expressed FLA gene in birch was transformed into Arabidopsis thaliana.Phenotypic observation showed that the stems of transgenic plants overexpressing BpFLA develop earlier,the inflorescence stems were higher and the leaves were larger than wild-type plants.These results suggest that the BpFLA gene was induced by BpNAC012 and has the function of promoting stem development.These results suggest that the expression of BpNAC012 regulates the metabolic pathway of xylem development and secondary cell wall synthesis,and then regulates the development of B.platyphylla xylem.