The Phylogenetic Analysis Of MADS-box Gene Family In Brassiceae Plants

The MADS-box gene family is a kind of transcription factor widely existing in plants,which contains a highly conserved domain(MADS domain)with a function of specifically combining a[CArG](A-riched)DNA fragment.This family plays an important role in the processes of flower,fruit,leaf and root developments in plants.It's quite abundant in higher plants.For example,it has been confirmed that there are 109 MADS-box genes existed in A.thaliana.The study of the evolution of this family has been fruitful.The origins of the whole family and of SRF-like and MEF2-like genes have been obviously clear——a duplication of TOPOIIA encoded by an ancestral prokaryote resulted into the ancestor of the family and another duplication of this ancestor resulted into the ancestors of SRP-like and MEF2-like genes.Besides,a number of evolution conclusions of the family has been inferred by large scale phylogeny studies of it.But those former studies mostly concentrate on the distant evolutionary history of the family.So this study focus on the resent——the evolutionary history of MADS-box gene family in Brassicaceae plants,to enrich our understanding of this family.Firstly,The sequencing qualities of the proteomic data of 27 current completely sequenced Brassicaceae plants were analyzed and 16 representative species was finally chosen as samples base on the current Brassicaceae plants classification system.And the closest 7 sequenced relatives of Brassicaceae plants were chosen as outgroup.Secondly,2168 MADS-box genes were identified.Finally,phylogenetic analyses were proceeded with these genes.The results of those phylogenetic analyses suggested that there were 50 MADS-box genes existed in the earliest common ancestor of current extant Brassicaceae plants(CACEBP)——19 type ? genes and 31 type ?genes.After a long period of time,19 type ? genes evolved into 38 genes of the most resent CACEBP——13 Ma,4 M? and 18 M? genes.Then they evolved into 38 MADS-box genes lineages in current extant Brassicaceae plants(CEBP).And those type ? genes evolved into 41 lineages in CEBP,which constitute 14 type ? subgroups——MIKC*-S,MIKC*-P,SEP,RSB1(AGL6/13),API,AG,FLC,SOC1,ANRI,AGL15,XAL(AGL12),SVP,AP3/PI and ABS.The former 2 subgroups are MIKC*-like genes.The other 12 subgroups are MIKCC genes and 6 subgroups of them,from ANR1 to ABS,have 12 lineages existing in current Brassicaceae plants which all have an origin before the earliest CACEBP came up.The other 6 subgroups have 24 lineages and 10 of them are just like the lineages of the former 6 subgroups,originated before the earliest CACEBP came up.Whereas the other 14 lineages formed from duplication events happened in earlier CACEBP.The research clearly reveals the distribution situation of MADS-box genes,the origins of lineages of MADS-box genes and their evolutionary relationships of MADS-box gene family,which means,in some degree,this study fulfill the closer evolutionary history of this family.