ID: 613 / 78

Category: Symposia

Track: Pending

Proposed Symposium Title: THE ROLE OF AGMATOPLOIDY AND SYMPLOIDY FOR DIVERSIFICATION OF FLOWERING PLANTS WITH HOLOCENTRIC CHROMOSOMES

Abstract: Polyploidisation is widely acknowledged as one of the most important processes driving evolution of flowering plants. On the contrary, the significance of agmatoploidy and symploidy for diversification of Angiosperms, i.e. concerted fission/fusion of holocentric chromosomes leading to increase/decrease in chromosome number, remains largely unknown and neglected in evolutionary studies. In holocentric chromosomes, spindle microtubules attach along the whole chromosome lengths through diffuse kinetochores. Therefore, their fusion/fragmentation is not necessarily deleterious, may affect genome-wide recombination rates, and can facilitate adaptation and speciation. Recurrent chromosomal fission/fusion during karyotype evolution can lead to a wide range of chromosome numbers, including continuous (dysploid) series. These processes have been evidenced in five angiosperm families (Convolvulaceae, Cyperaceae, Droseraceae, Juncaceae, and Melanthiaceae) but are likely more common. Most of the previous research has been dedicated to detection of agmato/symploidy in different species and uncovering underlying karyological processes, but evolutionary aspects such as frequency of chromosome fusions and fissions as well as their genetic basis remain largely understudied, or the knowledge limited to closed communities of botanists studying specific genera (e.g., Carex working group). We thus aim to bring together scientists working with different plant genera with incidence of agmato- or symploidy and thus bridge the gap in knowledge-flow regarding these processes and underlying mechanisms, for which the IBC provides a perfect platform. The symposium will provide theoretical backgrounds of agmato/symploidy from the cellular to the organismic level and beyond, and examine its importance for diversification of Carex and Luzula, the plant genera with high incidence of agmatoploidy. We invite especially speakers working with other families having holocentric chromosomes to provide insights on evolutionary aspects of agmato/symploidy for their diversification.

Speaker 1: František Zedek Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlárská 2, 61137, Brno, Czech Republic. E-mail: fzedek@gmail.com. Title: Evolutionary significance of holocentric chromosomes

Speaker 2: Carrie M. Tribble University of Hawai`i at Manoa, USA Email: ctribble09@gmail.com Title: The influence of chromosome evolution on diversification rates in Carex (Cyperaceae)

Speaker 3: Valentin Heimer Department of Botany, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria E-mail: valentin.heimer@student.uibk.ac.at. Title: Evolutionary and ecological aspects of agmatoploidy for diversification of Luzula sect. Luzula in the Eastern Alps

Topics (Up to three): Development and Structure

Topic 2: Systematics

Topic 3: Macroevolution

Justification: Our symposium bridges different topics, connecting developmental and structural grounds of development of holocentric chromosomes, macroevolutionary aspects of agmato/symploidy and their importance for diversification, and systematics and taxonomy of different lineages. The speakers are senior experienced scientist with several publications dedicated to agamato/symploidy, early-career scientist tackling these processes in Carex, and a PhD student disentangling evolutionary and ecological aspects of agmatoploidy in Luzula. We thus bring diversity of speakers in terms of gender, career stage, and geography. We also got a very positive feedback and interest in participation to this symposium from various colleagues conducting research on agmato/symploid genera.