Format: ORAL

Yan Campos Rizzieri1,Fay-Wei Li2, Stacy Holt3, James Beck4, Brittany Sutherland5, Nicholas Kooyers3, and Erin M. Sigel6

1. Cornell University, Ithaca, New York, USA 2. Boyce Thompson Institute, Ithaca, New York, USA 3. University of Louisiana at Lafayette, Lafayette, Louisiana, USA 4. Wichita State University, Wichita, Kansas, USA 5. George Mason University, Fairfax, Virginia, USA 6. University of New Hampshire, Durham, NH, USA

Among the ferns, a group rife with exceptionally large genome sizes and high chromosome numbers, the heterosporous water ferns are distinct for their small genomes. It has been posited that hetersporous ferns, as well as heterosporous lycophytes and seed plants, have more dynamic genome evolution following whole genome duplication than homoploid lineages, often leading to rapid downsizing and diploidization. As a first attempt to assess genome evolution in neopolyploid heterosporous ferns, we present a draft haplotype-resolved genome assembly for the natural allopentaploid Salvinia molesta (1C=2.28Gb). By comparing genic content, synteny, and repetitive element composition to the previously published Salvinia cucullata (1C=0.25Gb) and Azolla filiculoides genomes (1C=0.75Gb), we assess genomic and subgenomic changes in this recently formed polyploid fern. Additionally, we discuss our findings relative to comparable studies of other heterosporous polyploid seed plants and lycophytes, as well as homosporous ferns, providing phylogenetic context for understanding post-WGD genomic changes.