The Evolutionary And Functional Analysis Of Maize NAC Transcription Factor And Potential Target Gene Glycosyltransferase 47

Drought is one of abiotic stresses can severely affect plant growth and development.Plants respond to stress signals by sensing stress signals,and transmitting stress signals.The response to stress signals might involve all aspects of the plant,such as transcription regulation,translation,and apparent modification.The NAC family plays important roles in the responses to abiotic stress.Glycosyltransferase family 47(GT47)genes encode ?-galactosyltransferases and ?-glucuronyltransferases that synthesize pectin,xyloglucans and xylan,which are important components of the plant cell wall.So GT47 family plays roles in cell wall biosynthesis.In the study,we research the evolution and function of NAC and GT47 gene family ranging from lower to higher plants(algae,moss,ferns,gymnosperms,monocots and dicots)using phylogenetic analysis.The results are as follows:1.In all,5779 sequences,were retrieved from 50 plants(moss,ferns,gymnosperms,monocots and dicots).The copy number of NAC genes varies considerably,ranging from 20 in the moss Selaginella moellendorffii to 275 in the dicots Malus x domestica.There was no NAC genes in the green algae Chlamydomonas reinhardtii.The copy number variation in plants was mainly due to whole genome duplication and/or tandem duplication.2.Phylogenetic analyses showed that the plant NAC genes can be divided into 12 subfamilies,names as clade I-XII.These clades can be further grouped into four categories: six shared by all land plant;one shared by gymnosperm and angiosperm;one shared by ferns;and four angiosperm specific clades.Meanwhile,the expansion of these clades was different between monocots and dicots.Then our study showed that different motifs and conserved amino acid sites in different clades.We identified five subclades which might respond to drought stress.3.The genomic synteny network showed that the NAC gene family was involved to complicated synteny network.The synteny network contained 3728 NAC genes that were linked by 34001 syntenic edges.We clustered the synteny networks and obtained 95 subnetworks,names as clusters1-95.Then we found that some clusters were conserved in angiosperms suggesting that some NAC subfamilies might have conserved function.In addition,we found some lineage-specific clusters in monocots or dicots.This indicted that the evolutionary pattern of some NAC subfamilies was different between monocots and dicots.4.The transcriptional expression profiling and ribosome profiling of maize NAC genes showed that drought stress differentially altered gene expression of NAC genes at both transcriptional and translational levels,and then changed the gene translational efficiency.We found that 50 genes showed significant responses to drought stress with different manners(three tissues and four stages)and we verified that 20 NAC genes are differentially expressed genes under drought stress using real-time quantitative PCR.In addition,our results indicated that NAC genes play roles in maize seed development.5.The transcriptional regulatory network analysis of maize NAC genes indicated that the target genes of NAC transcription factor were enriched in 18 biological processes that contained salt stress,heat stress and the biosynthetic and metabolic process of lignin,which is the major component of cell wall.The research of GT47 gene family that is relative to the biosynthetic of cell wall was very few.6.We identified 352 GT47 genes from 15 representative plants(algae,moss,ferns,gymnosperms,monocots and dicots).The phylogenetic analysis results showed that GT47 gene might originate in cyanobacteria.Further research in maize,we found that the 47 GT47 genes can divide into five subfamilies(clade I-V)with diverse exon–intron structures.Among these five clades,two clades were mainly composed of intron-poor genes.Gene duplication analysis revealed that the expansion of GT47 gene family in maize was significantly driven from tandem duplication events and segmental duplication events.Significantly,almost all duplicated genes were intron-poor genes.7.The transcriptional expression profiling and ribosome profiling of maize GT47 genes showed that several intron-poor GT47 genes might be involved in the drought stress response and seed development in maize.Then we found three GT47 genes that respond to drought stress using real-time quantitative PCR.