title: Dissecting Abscisic Acid Signaling Pathways Involved in Cuticle Formation.
abstract: The cuticle is the outer physical barrier of aerial plant surfaces and an important interaction point between plants and the environment. Many environmental stresses affect cuticle formation, yet the regulatory pathways involved remain undefined. We used a genetics and gene expression analysis in Arabidopsis thaliana to define an abscisic acid (ABA) signaling loop that positively regulates cuticle formation via the core ABA signaling pathway, including the PYR/PYL receptors, PP2C phosphatase, and SNF1-Related Protein Kinase (SnRK) 2.2/SnRK2.3/SnRK2.6. Downstream of the SnRK2 kinases, cuticle formation was not regulated by the ABA-responsive element-binding transcription factors but rather by DEWAX, MYB16, MYB94, and MYB96. Additionally, low air humidity increased cuticle formation independent of the core ABA pathway and cell death/reactive oxygen species signaling attenuated expression of cuticle-biosynthesis genes. In Physcomitrella patens, exogenous ABA suppressed expression of cuticle-related genes, whose Arabidopsis orthologs were ABA-induced. Hence, the mechanisms regulating cuticle formation are conserved but sophisticated in land plants. Signaling specifically related to cuticle deficiency was identified to play a major role in the adaptation of ABA signaling pathway mutants to increased humidity and in modulating their immunity to Botrytis cinerea in Arabidopsis. These results define a cuticle-specific downstream branch in the ABA signaling pathway that regulates responses to the external environment.
authors.affiliation: Division of Plant Biology, Viikki Plant Science Centre, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland. Electronic address: fuqiang.cui@helsinki.fi.
authors.forename: Fuqiang
authors.initials: F
authors.lastname: Cui
authors.affiliation: Division of Plant Biology, Viikki Plant Science Centre, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland; Institute of Technology, University of Tartu, Nooruse 1, Tartu 50411, Estonia.
authors.forename: Mikael
authors.initials: M
authors.lastname: Brosché
authors.affiliation: Department of Agricultural Sciences, University of Helsinki, PO Box 27, 00014 Helsinki, Finland.
authors.forename: Mikko T
authors.initials: MT
authors.lastname: Lehtonen
authors.affiliation: Division of Plant Biology, Viikki Plant Science Centre, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Ali
authors.initials: A
authors.lastname: Amiryousefi
authors.affiliation: Division of Plant Biology, Viikki Plant Science Centre, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Enjun
authors.initials: E
authors.lastname: Xu
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, Turku 20014, Finland.
authors.forename: Matleena
authors.initials: M
authors.lastname: Punkkinen
authors.affiliation: Department of Agricultural Sciences, University of Helsinki, PO Box 27, 00014 Helsinki, Finland.
authors.forename: Jari P T
authors.initials: JP
authors.lastname: Valkonen
authors.affiliation: Department of Biochemistry, Molecular Plant Biology, University of Turku, Turku 20014, Finland.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Fujii
authors.affiliation: Division of Plant Biology, Viikki Plant Science Centre, Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Kirk
authors.initials: K
authors.lastname: Overmyer
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D019068:Bryopsida / Q000378:metabolism / Q000502:physiology; D018506:Gene Expression Regulation, Plant
chemical_list: D029681:Arabidopsis Proteins; D000040:Abscisic Acid
keywords: Arabidopsis; Botrytis; Physcomitrella; abscisic acid; cuticle; land plants