Evolution and function of Marchantia BBR/BPC proteins

• Applicant: Professor Dr. Dierk Wanke
• Subject Area: Plant Physiology
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443101600

This short term project addresses the question whether the molecular biochemical functions of BBR/BPC proteins were already established in the dioecious liverwort Marchantia, as one of the earliest land plants, and maintained throughout evolution, or not.Because of the conserved tripartide domain structure, it might be possible that Marchantia MpBBR1 and MpBBR2 can form homodimers and heterodimers with MpLHP1. Based on our data from the orthologous proteins in Arabidopsis, it might be possible that MpLHP1 can be recruited by MpBBR1 or MpBBR2 to GAGA-motif containing DNA-probes. The concerted action of the MpBBR-MpLHP1 complex will presumably target homeotic genes and, hence, might be important for the development of reproductive organs. Cross-species heterodimer formation between Arabidopsis LHP1 or group II BBR/BPCs and Marchantia LHP1 or group IV BBR/BPC members will disclose whether the molecular functional capacities were maintained throughout land plant evolution.Against the background of my hypotheses, I will address the following central questions:• Are MpBBR1 and MpBBR2 forming homodimers in vivo? Where do the proteins localize inside the nucleus? As a consequence of gametophytic dioecy, it is important to know whether MpBBR1 - MpBBR2 homotypic heterodimers can form in the zygote.• Are both MpBBR1 and MpBBR2 able to interact with MpLHP1? Is this interaction restricted to the nucleoplasm, similar to their Arabidopsis othologs?• Are orthologous proteins from Arabidopsis and Marchantia able to form dimers in vivo?• Are MpBBR1 and MpBBR2 binding to GAGA-DNA-motifs? If so, it is important to know whether MpLHP1 can be recruited by MpBBR1 or MpBBR2 to GAGA-motifs.• Are MpBBR1 and MpBBR2 targeting MADS-box gene promoters - similar to their Arabidopsis orthologs?

• DFG Programme: Research Grants