The Evolution Mechanism Of The Key Genes GIGANTEA And CONSTANS In Photoperidic Pathway

GI and CO play an important role in the flowering induction of plant photoperiod.GI is an essential gene about biological clock output and regulate and controlthe expressionofCO positively.COcan carry out the integration of the optical signal and the biological clock signal,and activate the expression of downstream FT to induce plants flowering.Therefore,this study identified all GI and CO copies from 14 genomes by bioinformatics methods.The phylogenetic analysis of exon intron structure,domain and motif analysis,gene duplication and differential expression analysis was conducted to investigate the potential roles of GI and CO gene families in plants.1?GI and CO gene families of 14 species whose genomes have been sequenced(long day plants,short day plants and neutral each three kinds of plants,species of thallophytes,pteridophyta,bryophyta and gymnosperms each one,as well as the primitive angiosperms Amborella trichopoda)were studied.And theresultshowedthatthemembers of the family of GI and CO were 20 and 159 in theses 14 species,respectively.2? Phylogenetic analysis showed that 20 GIin 14 plant genomes can be divided into two clades which wereMonocotyledoneae and dicotyledon.The 159 CO can be divided into B1-B3 clades which were based on their domain clustering.And each representing had an original gene lineage.3?209 of the 20 GI are in introns,145 were phase 0 and phase 1 and phase 2 were only 31 and 32.A large number of symmetric exons are formed.In the subfamilies of B1-B3 ofCO,most genes existed in 2-4 exons.It especially showed the presence of 4 exons and 3 introns in each CO in the B2 subfamily,and they are also the same phase 0,0 and 2 arrangements.This indicated that the evolution of the CO structure on exome shuffling and intron deletion may play a certain role.4?Genome duplication plays a key role in the amplification and evolution of GI and CO genes families in plants.The gene structure,chromosomal location and genome-wideGI and CO showed that tandem and partial duplications,as well as the entire genome duplication may effect the amplification and evolution of plant gene families,eventually leading to the diversity of the gene numbers,structure and functionof GI and CO.In Arabidopsis thaliana,Phaseolus vulgaris and Ricinus communis,COfamily has extensive synteny.And syntenic regions containing multiple genes,suggests that these genes may have a common ancestor and known biological characteristics in evolution.