Identification And Comparative Evolution Of CONSTANS-like Gene Families In Four Cruciferous Plants And Expression Patterns Of COL Genes In Arabidopsis Pumila

The proteins encoded by CONSTANS(CO)and CONSTANS-like(COL)genes are photoperiod transcription factors involved in regulating plant growth and development and responding to adversity stress.CO gene is a key gene that regulates photoperiod flowering in plants,which regulates the floral transition by promoting or inhibiting the expression of downstream genes.In this study,we used comparative genomics and bioinformatics methods to study the characteristics ofCOL gene family from four Brassicaceae,Arabidopsis thaliana,Arabidopsis lyrata,Arabidopsis pumila and Camelina sativa.TheCOL transcription factor family genes of four cruciferous plants were analyzed by phylogenetic analysis,gene structure,conserved motif,chromosome distribution and collinearity.The expression patterns of Arabidopsis pumilaCOL genes in 15 different tissues,five different developmental stages,and under high salt stress were analyzed using RNA-seq data of Arabidopsis pumila.The expression patterns of ApCOL gene members under long-day and short-day conditions,as well as abiotic stresses were analyzed by q RT-PCR.The main research contents and results of this thesis are as follows:1.Genome-wide identification and comparative evolutionary analysis ofCOL gene families in four cruciferous plants(1)The genome-wide analysis identified 17,17,34,and 51COL genes from Arabidopsis thaliana,Arabidopsis lyrata,Arabidopsis pumila,and Camelina sativa,respectively.(2)Phylogenetic analysis showed thatCOL genes in the four Brassicaceae species were divided into three subgroups,?,?and?.(3)Each group ofCOL proteins contains a typical B-box and CCT domain.The subgroup?contained 43COL genes,and subgroup?and subgroup?contained 28 and 48 ApCOL genes,respectively.(4)The exon-intron and conserved motifs ofCOL members in the same subgroup are highly similar,and each subgroup has its own unique motif.(5)101 pairs of paralogous genes and 269 pairs of orthologous genes were identified from the four species.Ka/Ks analysis showed that theCOL genes mainly underwent purification selection during evolution.(6)Molecular evolution and collinearity analysis revealed that tandem duplication and whole genome duplication(WGD)events played important roles in the expansion ofCOL family in the four species.2.2.Expression profile analysis ofCOL genes in Arabidopsis pumila(1)There are various cis-acting elements in the upstream promoter sequence of ApCOL genes,such as light response,environmental stress,growth and development,and hormone response.(2)Analysis of the RNA-seq data from 15 different tissues demonstrateded that 7 ApCOL genes(ApCO1,ApCOL1.1,ApCOL1.2,ApCOL2.1,ApCOL2.2,ApCOL7.1,and ApCOL7.2)possessed higher expression levels in cotyledon;ApCOL11.1,ApCOL12.1,and ApCOL12.2 had higher expression levels in bud.The expression levels of ApCOL11.2 and ApCOL12.2 were higher in flowers than other tissues.(3)The RNA-seq data of the five growth and development stages revealed that the expression of ApCOLs were gradually up-regulated in the five different development stages.(4)q RT-PCR confirmed that the expression of four ApCOL genes(ApCOL1.1,ApCOL1.2,ApCOL2.1 and ApCOL13.2)responded to salt(250 mmol·L^-1 Na Cl),drought(15%PEG6000),methylviologen(1?mo/L MV),and abscisic acid(1?mo/L ABA).(5)Rhythm expression analysis showed that the expression levels of ApCOL1.1/1.2,ApCOL2.1/2.2 and ApCOL5.1/5.2were firstly increased and then decreased under short-day conditions(8 h light,16 h dark),showing an obvious diurnal circadian expression pattern.In this study,a total of 119COL genes were identified from the genomes of four Brassicaceae species.WGD/fragment duplication was the main reason for the expansion of the AtCOL,AlCOL,ApCOL,and CsCOL genes,and purification selection is the main force for theCOL gene family evolution.Some of the ApCOL replicating genes have structural differences,which may lead to functional differences.ApCOL1.1,ApCOL1.2,ApCOL2.1,and ApCOL13.2 genes play important roles in regulating the growth and development of Arabidopsis pumila and its response to abiotic stress.Six ApCOL genes(ApCOL1.1/1.2,ApCOL2.1/2.2,and ApCOL5.1/5.2)probably function in the photoperiod flowering pathway of Arabidopsis pumila.