Isolation and characterization of new MIKC*-Type MADS-box genes from the moss Physcomitrella patens.

MADS-box genes encode for a large family of transcription-regulating proteins, which were isolated from all groups of eukaryotic organisms. The plant-specific MIKC-type MADS-box genes have been intensively analyzed for their roles in controlling developmental processes. Well-known are the MADS-box genes acting as homeotic selector genes in the differentiation of whorls of floral organs in seed plants. The MADS-box gene family has also been studied in non-flowering plants, such as lycophytes, pteridophytes, and bryophytes. The analysis of MADS-box genes in the moss Physcomitrella patens led to the identification of a new class of MIKC-type genes, designated as MIKC*-type genes. The MIKC*-type genes possess a number of structural features which clearly distinguish them from the already known MIKC-type genes. Recently, orthologues of the Physcomitrella MIKC*-type genes were found in Arabidopsis thaliana, demonstrating the conservation of these genes in tracheophytes. Here, we report the isolation of two new MIKC*-type MADS-box genes from Physcomitrella. Structural features and expression patterns of these genes were analyzed. The contribution of our findings to a better understanding of the evolution of MIKC*-type genes in land plants is discussed.