Format: ORAL

Manuel Waller1,2, Ueli Grossniklaus2,3, Karen Renzaglia4, Eftychios Frangedakis5, Keiko Sakakibara6, Kazune Ezaki6, Pter Szvnyi1,2 

1 Department of Systematic and Evolutionary Botany, University of Zurich, Zurich, Switzerland  2 Zurich-Basel Plant Science Center, Zurich, Switzerland  3 Department of Plant and Microbial Biology, University of Zurich, Zurich, Switzerland  4 Department of Plant Biology, Southern Illinois University, Illinois, USA 5 Department of Plant Sciences, University of Cambridge, Cambridge, UK 6 Department of Life Science, Rikkyo University, Tokyo, Japan

The diploid spore producing sporophyte of land plants is thought to have been interpolated into a primarily haplontic ancestral life cycle as an adaptation to life on dry land. However, between the two monophyletic land plant clades, the bryophytes and vascular plants, sporophyte evolution has followed contrasting trajectories. Bryophyte sporophytes are nutritionally dependent on the gametophyte, uniaxial and monosporangiate, while vascular plant sporophytes have evolved complex branched body plans with a variety of lateral organs to become nutritionally independent. Little is known about how regulatory processes of sporophyte development have evolved and contributed to the diversification of sporophyte functions and morphology. Comparative analyses on sporophyte development and conclusions on developmental homologies have primarily been drawn using the model moss Physcomitrium patens and the liverwort Marchantia polymorpha, in comparison to the well-studied development of flowering plants. However, sporophytes of the three lineages of bryophytes exhibit considerably different growth patterns and insights into shared regulatory mechanisms of sporophyte development can only be achieved by simultaneously investigating all three bryophyte lineages. With the recent establishment of Anthoceros agrestis as a hornwort model, genomic and sporophyte transcriptomic data has become available. Therefore, to gain insight into shared and divergent regulatory mechanisms among liverworts, mosses, and hornworts, we compared sporophyte specific gene expression across the three bryophyte models by creating and analyzing sporophyte and gametophyte enriched transcriptome datasets for M. polymorpha, P. patens and A. agrestis. Furthermore, using laser capture microdissection, we generated tissue-specific transcriptomes for distinct tissues within the A. agrestis sporophyte proliferative zone and analyzed differential gene expression between these sporophyte tissues, to provide the first insight into the genetic control of hornwort sporophyte development. Using fluorescent reporter and overexpression lines we provide our first results concerning the ancestral function of key developmental genes in the sporophyte development of bryophytes and land plants.