Fern genomes elucidate land plant evolution and cyanobacterial symbioses
Li, Fay-Wei; Brouwer, Paul; Carretero-Paulet, Lorenzo; Cheng, Shifeng; De Vries, Jan; Delaux, Pierre-Marc; Eily, Ariana; Koppers, Nils; Kuo, Li-Yaung; Li, Zheng; Simenc, Mathew; Small, Ian; Wafula, Eric; Angarita, Stephany; Barker, Michael S.; Brautigam, Andrea; DePamphilis, Claude; Gould, Sven; Hosmani, Prashant S.; Huang, Yao-Moan; Huettel, Bruno; Kato, Yoichiro; Liu, Xin; Maere, Steven; McDowell, Rose; Mueller, Lukas A.; Nierop, Klaas G.J.; Rensing, Stefan A.; Robison, Tanner; Rothfels, Carl J.; Sigel, Erin M.; Song, Yue; Timilsena, Prakash R.; Van de Peer, Yves; Wang, Hongli; Wilhelmsson, Per K.I.; Wolf, Paul G.; Xu, Xun; Der, Joshua P.; Schluepmann, Henriette; Wong, Gane K.-S.; Pryer, Kathleen M.
Date:
2018-07-02
Abstract:
Ferns are the closest sister group to all seed plants, yet little is known about their genomes other than that they are generally
colossal. Here, we report on the genomes of Azolla filiculoides and Salvinia cucullata (Salviniales) and present evidence for
episodic whole-genome duplication in ferns—one at the base of ‘core leptosporangiates’ and one specific to Azolla. One fernspecific
gene that we identified, recently shown to confer high insect resistance, seems to have been derived from bacteria
through horizontal gene transfer. Azolla coexists in a unique symbiosis with N2-fixing cyanobacteria, and we demonstrate a
clear pattern of cospeciation between the two partners. Furthermore, the Azolla genome lacks genes that are common to arbuscular
mycorrhizal and root nodule symbioses, and we identify several putative transporter genes specific to Azolla–cyanobacterial
symbiosis. These genomic resources will help in exploring the biotechnological potential of Azolla and address fundamental
questions in the evolution of plant life.
