Ferns: The Final Frond-tier in Plant Model Systems

Abstract

Ferns are one of the most speciose lineages of land plants, and occupy an important phylogenetic position sister to seed plants. Despite this, ferns remain one of the last groups of land plants that do not have a fully developed model system. Here we review the biology and status of each emerging fern model. While reference genomes have been completed for Azolla filiculoides and Salvinia cucullata, they lack transformation capability. Meanwhile, other ferns including Marsilea vestita, Adiantum capillus-veneris, Pteris vittata, and Ceratopteris richardii have transformation methods, but lack genomic resources. Nevertheless, as genome sequencing becomes increasingly more affordable, we believe that M. vestita and C. richardii can become powerful fern models, which represent heterosporous and homosporous ferns, respectively.