Poster

         Development and Structure

Building a model system to study capitulum development and evolution in the Asteraceae

Presenting Author
Reid Selby
Description
With over 30,000 species, Asteraceae is the largest family of flowering plants. While the family displays remarkable ecological and morphological diversity, the highly compact inflorescence known as a capitulum is present in each species, forming a pseudanthium of many florets that functions as a single flower. These “false flowers” may be partially responsible for the family’s global expansion and success. While the evolutionary origin of this highly conserved structure is unclear, it is commonly thought to be derived from a raceme, with drastic reduction in inflorescence internode length. Understanding the developmental genetics underlying capitulum formation is key to understanding the Asteraceae; however, due to large genome sizes, resistance to stable genetic transformation, and lack of standardized lab protocols, relatively few genetic and genomic resources are available to researchers studying the Asteraceae. In the CapituLab at Auburn University, we are building a model system to explore the genetics of capitulum development using Bidens cv. Compact Yellow. Compact Yellow is a promising candidate model system as it has a compact growth habit and short generation times. Compact Yellow also has a relatively small genome, self-fertilizes, and easily propagates from cuttings. Here we present a highly contiguous, haplotype-resolved genome assembly of Compact Yellow using long-read PacBio HiFi sequencing coupled with Hi-C chromatin mapping. Along with these genome assemblies, we are identifying gene regulatory networks controlling flower development in Compact Yellow by using transcriptomics coupled with confocal microscopy targeting distinct stages of capitulum development. Finally, to test hypotheses about flower development via reverse genetics, we are also building reliable genetic transformation methods using in vitro tissue culture and Agrobacterium tumefaciens. A reference genome, transformation capabilities, and a foundational understanding of inflorescence development lay the groundwork for an exciting model system in which to study Asteraceae capitulum development.