title: Abscisic acid controlled sex before transpiration in vascular plants.
abstract: Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fernCeratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.
authors: School of Biological Sciences, University of Tasmania, Hobart, TAS 7001, Australia.
authors: Scott A M
authors: SAM
authors: McAdam
authors: School of Biological Sciences, University of Tasmania, Hobart, TAS 7001, Australia; timothyb@utas.edu.au banksj@purdue.edu hedrich@botanik.uni-wuerzburg.de.
authors: Timothy J
authors: TJ
authors: Brodribb
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; timothyb@utas.edu.au banksj@purdue.edu hedrich@botanik.uni-wuerzburg.de.
authors: Jo Ann
authors: http://orcid.org/0000-0002-7762-7261
authors: JA
authors: Banks
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Wuerzburg, Germany; timothyb@utas.edu.au banksj@purdue.edu hedrich@botanik.uni-wuerzburg.de.
authors: Rainer
authors: R
authors: Hedrich
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907.
authors: Nadia M
authors: NM
authors: Atallah
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907.
authors: Chao
authors: C
authors: Cai
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Wuerzburg, Germany.
authors: Michael A
authors: MA
authors: Geringer
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Wuerzburg, Germany.
authors: Christof
authors: C
authors: Lind
authors: Central Science Laboratory, University of Tasmania, Hobart, TAS 7001, Australia.
authors: David S
authors: DS
authors: Nichols
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907.
authors: Kye
authors: K
authors: Stachowski
authors: Institute for Molecular Plant Physiology and Biophysics, University of Würzburg, D-97082 Wuerzburg, Germany.
authors: Dietmar
authors: http://orcid.org/0000-0003-0715-5710
authors: D
authors: Geiger
authors: School of Biological Sciences, University of Tasmania, Hobart, TAS 7001, Australia.
authors: Frances C
authors: FC
authors: Sussmilch
keywords: OST1; evolution; fern; sex determination; stomata