- Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
Kwantes, Michiel; Liebsch, Daniela; Verelst, Wim
Land plants have a remarkable life cycle that alternates between a diploid sporophytic and a haploid gametophytic generation, both of which are multicellular and changed drastically during evolution. Classical MIKC MADS-domain (MIKC(C)) transcription factors are famous for their role in sporophytic development and are considered crucial for its evolution. About the regulation of gametophyte development, in contrast, little is known. Recent evidence indicated that the closely related MIKC* MADS-domain proteins are important for the functioning of the Arabidopsis thaliana male gametophyte (pollen). Furthermore, also in bryophytes, several MIKC* genes are expressed in the haploid generation. Therefore, that MIKC* genes have a similar role in the evolution of the gametophytic phase as MIKC(C) genes have in the sporophyte is a tempting hypothesis. To get a comprehensive view of the involvement of MIKC* genes in gametophyte evolution, we isolated them from a broad variety of vascular plants, including the lycophyte Selaginella moellendorffii, the fern Ceratopteris richardii, and representatives of several flowering plant lineages. Phylogenetic analysis revealed an extraordinary conservation not found in MIKC(C) genes. Moreover, expression and interaction studies suggest that a conserved and characteristic network operates in the gametophytes of all tested model organisms. Additionally, we found that MIKC* genes probably evolved from an ancestral MIKC(C)-like gene by a duplication in the Keratin-like region. We propose that this event facilitated the independent evolution of MIKC* and MIKC(C) protein networks and argue that whereas MIKC(C) genes diversified and attained new functions, MIKC* genes retained a conserved role in the gametophyte during land plant evolution.
MIKC*; gametophyte; K-domain; evolution; gene duplication; MADS
Molecular Biology and Evolution
2012, Volume: 29, number: 1, pages: 293-302
Publisher: OXFORD UNIV PRESS
Biochemistry and Molecular Biology