title: Expansion and Functional Divergence of AP2 Group Genes in Spermatophytes Determined by Molecular Evolution andArabidopsisMutant Analysis.
abstract: TheAPETALA2(AP2) genes represent the AP2 group within a large group of DNA-binding proteins called AP2/EREBP. TheAP2gene is functional and necessary for flower development, stem cell maintenance, and seed development, whereas the other members of AP2 group redundantly affect flowering time. Here we study the phylogeny of AP2 group genes in spermatophytes. Spermatophyte AP2 group genes can be classified into AP2 and TOE types, six clades, and we found that the AP2 group homologs in gymnosperms belong to the AP2 type, whereas TOE types are absent, which indicates the AP2 type gene are more ancient and TOE type was split out of AP2 type and losing the major function. In Brassicaceae, the expansion of AP2 and TOE type lead to the gene number of AP2 group were up to six. Purifying selection appears to have been the primary driving force of spermatophyte AP2 group evolution, although positive selection occurred in the AP2 clade. The transition from exon to intron ofAtAP2inArabidopsismutant leads to the loss of gene function and the same situation was found inAtTOE2. Combining this evolutionary analysis and published research, the results suggest that typical AP2 group genes may first appear in gymnosperms and diverged in angiosperms, following expansion of group members and functional differentiation. In angiosperms,AP2genes (AP2 clade) inherited key functions from ancestors and other genes of AP2 group lost most function but just remained flowering time controlling in gene formation. In this study, the phylogenies of AP2 group genes in spermatophytes was analyzed, which supported the evidence for the research of gene functional evolution of AP2 group.
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry UniversityNanjing, China; Suzhou Polytechnic Institute of AgricultureSuzhou, China.
authors.forename: Pengkai
authors.initials: P
authors.lastname: Wang
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Tielong
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Laboratory of Biotechnology, Chinese Academy of Forestry Beijing, China.
authors.forename: Mengzhu
authors.initials: M
authors.lastname: Lu
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Guangxin
authors.initials: G
authors.lastname: Liu
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Meiping
authors.initials: M
authors.lastname: Li
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Jisen
authors.initials: J
authors.lastname: Shi
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Institute of Biology III, University of Freiburg Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Laux
authors.affiliation: Ministry of Education, Key Laboratory of Forest Genetics and Biotechnology, Nanjing Forestry University Nanjing, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Chen
keywords: AP2 group gene; arabidopsis mutants; functional divergence; phyllogeny; selective pressures; spermatophyte