title: Evolution of abscisic acid synthesis and signaling mechanisms.
abstract: The plant hormone abscisic acid (ABA) mediates seed dormancy, controls seedling development and triggers tolerance to abiotic stresses, including drought. Core ABA signaling components consist of a recently identified group of ABA receptor proteins of the PYRABACTIN RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family that act as negative regulators of members of the PROTEIN PHOSPHATASE 2C (PP2C) family. Inhibition of PP2C activity enables activation of SNF1-RELATED KINASE 2 (SnRK2) protein kinases, which target downstream components, including transcription factors, ion channels and NADPH oxidases. These and other components form a complex ABA signaling network. Here, an in depth analysis of the evolution of components in this ABA signaling network shows that (i) PYR/RCAR ABA receptor and ABF-type transcription factor families arose during land colonization of plants and are not found in algae and other species, (ii) ABA biosynthesis enzymes have evolved to plant- and fungal-specific forms, leading to different ABA synthesis pathways, (iii) existing stress signaling components, including PP2C phosphatases and SnRK kinases, were adapted for novel roles in this plant-specific network to respond to water limitation. In addition, evolutionarily conserved secondary structures in the PYR/RCAR ABA receptor family are visualized.
authors.affiliation: Division of Biological Sciences, Cell and Developmental Biology Section, University of California San Diego, La Jolla, CA 92093-0116, USA.
authors.forename: Felix
authors.initials: F
authors.lastname: Hauser
authors.forename: Rainer
authors.initials: R
authors.lastname: Waadt
authors.forename: Julian I
authors.initials: JI
authors.lastname: Schroeder
mesh_terms: D000040:Abscisic Acid / Q000096:biosynthesis* / Q000235:genetics; D000220:Adaptation, Biological / Q000235:genetics / Q000502:physiology*; D005075:Biological Evolution; D017124:Conserved Sequence / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D010944:Plants; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D050436:Regulatory Elements, Transcriptional / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013045:Species Specificity; D014867:Water
chemical_list: D008565:Membrane Proteins; D014867:Water; D000040:Abscisic Acid; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases