Plants are thought to have started moving to land 500 million years ago. The algae are presumed to have been carrying the redundant genes since then. So did they then pre-exist the move to land?
From ScienceDaily:
500 million years ago, the first plants living in water took to land. The genetic adaptations associated with this transition can already be recognized in the genome of Chara braunii, a species of freshwater algae. An international research team headed by Marburg biologist Stefan Rensing reports on this in the journal Cell.
Rainer Hedrich and Dirk Becker from Julius-Maximilians-Universität Würzburg (JMU) in Bavaria, Germany, are also members of this team. “The genes of the Chara braunii alga comprises numerous evolutionary innovations that have been ascribed only to land plants so far,” Professor Hedrich explains; he is the head of JMU’s Chair of Molecular Plant-Physiology and Biophysics.
The stress hormone abscisic acid (ABA) is one of these innovations. It makes land plants switch to water saving mode during dry conditions. In water plants, this function is redundant. Still these early synthesis steps for ABA are already included in the genes of Chara braunii algae according to Hedrich. The matching hormone receptors in contrast are nowhere to be Paper. (paywall) – Tomoaki Nishiyama, Hidetoshi Sakayama, Jan de Vries, Henrik Buschmann, Denis Saint-Marcoux, Kristian K. Ullrich, Fabian B. Haas, Lisa Vanderstraeten, Dirk Becker, Daniel Lang, Stanislav Vosolsobě, Stephane Rombauts, Per K.I. Wilhelmsson, Philipp Janitza, Ramona Kern, Alexander Heyl, Florian Rümpler, Luz Irina A. Calderón Villalobos, John M. Clay, Roman Skokan, Atsushi Toyoda, Yutaka Suzuki, Hiroshi Kagoshima, Elio Schijlen, Navindra Tajeshwar, Bruno Catarino, Alexander J. Hetherington, Assia Saltykova, Clemence Bonnot, Holger Breuninger, Aikaterini Symeonidi, Guru V. Radhakrishnan, Filip Van Nieuwerburgh, Dieter Deforce, Caren Chang, Kenneth G. Karol, Rainer Hedrich, Peter Ulvskov, Gernot Glöckner, Charles F. Delwiche, Jan Petrášek, Yves Van de Peer, Jiri Friml, Mary Beilby, Liam Dolan, Yuji Kohara, Sumio Sugano, Asao Fujiyama, Pierre-Marc Delaux, Marcel Quint, Günter Theißen, Martin Hagemann, Jesper Harholt, Christophe Dunand, Sabine Zachgo, Jane Langdale, Florian Maumus, Dominique Van Der Straeten, Sven B. Gould, Stefan A. Rensing. The Chara Genome: Secondary Complexity and Implications for Plant Terrestrialization. Cell, 2018; 174 (2): 448 DOI: 10.1016/j.cell.2018.06.033 More.
File under: Maybe there is an evolutionary program of some sort.
See also: Did algae trigger complex cells before 650 million years ago?
Algae already possessed genes for land, while in water (2015)