Format: ORAL

Julian V. Garrecht1; Julian Ingelfinger2; Annette Becker1

1 Institute of Botany, Justus-Liebig University Gießen, 35392 Giessen, Germany 2 Technical University of Kaiserslautern, 67663 Kaiserslautern, Germany

The adaptation of reproductive strategies to the terrestrial environment was one of the crucial steps of the transition from water to land that plants had to overcome. During land plant evolution, various adaptations emerged, from the simple, water-dependent fertilization mechanism of bryophytes to the morphologically highly diverse flowers of angiosperms. This wide range of reproductive strategies makes it especially noteworthy that some of the essential regulators of flower development in angiosperms are present in all major land plant lineages. In Arabidopsis thaliana, the transcriptional regulators LEUNIG (LUG) and SEUSS (SEU) play an important role in flower development: LUG and SEU first form a heterodimer, which then can interact with floral organ identity proteins such as APETALA1, and other developmental regulators such as AINTEGUMENTA. The moss Physcomitrium patens encodes, like Arabidopsis, several homologs of LUG and SEU, raising the questions of (1) how exactly did these regulators co-evolve with each other and other transcriptional regulators to become such important floral regulators, and (2) if their ancestral function was also related to sexual development. We use Yeast-Two Hybrid and Bifluorescence Complementation assays to study protein interactions and the CRISPR-Cas system for multiplex Physcomitrium mutagenesis. We present our data on (1) the protein interaction of the Physcomitrium and other land plant LUG and SEU homologs and the protein domains important in the co-evolution between LUG and SEU and their interactors, heterodimer formation and for target protein interaction. Further, we show that removing LUG and SEU function from the Physcomitrium genomes results in growth retardation and will present detailed phenotypic analysis of the LUG and SEU mutants of Physcomitrium.