AUTHOR=Chen Fei , Zhang Xingtan , Liu Xing , Zhang Liangsheng 

TITLE=Evolutionary Analysis of MIKCc-Type MADS-Box Genes in Gymnosperms and Angiosperms

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00895

DOI=10.3389/fpls.2017.00895

ISSN=1664-462X

ABSTRACT=<p>MIKC<sup>c</sup>-type MADS-box genes encode transcription factors that control floral organ morphogenesis and flowering time in flowering plants. Here, in order to determine when the subfamilies of MIKC<sup>c</sup> originated and their early evolutionary trajectory, we sampled and analyzed the genomes and large-scale transcriptomes representing all the orders of gymnosperms and basal angiosperms. Through phylogenetic inference, the MIKC<sup>c</sup>-type MADS-box genes were subdivided into 14 monophyletic clades. Among them, the gymnosperm orthologs of <italic>AGL6, SEP</italic>, <italic>AP1</italic>, <italic>GMADS</italic>, <italic>SOC1</italic>, <italic>AGL32</italic>, <italic>AP3</italic>/<italic>PI</italic>, <italic>SVP</italic>, <italic>AGL15</italic>, <italic>ANR1</italic>, and <italic>AG</italic> were identified. We identified and characterized the origin of a novel subfamily <italic>GMADS</italic> within gymnosperms but lost orthologs in monocots and Brassicaceae. ABCE model prototype genes were relatively conserved in terms of gene number in gymnosperms, but expanded in angiosperms, whereas <italic>SVP</italic>, <italic>SOC1</italic>, and <italic>GMADS</italic> had dramatic expansions in gymnosperms but conserved in angiosperms. Our results provided the most detailed evolutionary history of all MIKC<sup>c</sup> gene clades in gymnosperms and angiosperms. We proposed that although the near complete set of MIKC<sup>c</sup> genes had evolved in gymnosperms, the duplication and expressional transition of ABCE model MIKC<sup>c</sup> genes in the ancestor of angiosperms triggered the first flower.</p>