title: Leaf epinasty and auxin: A biochemical and molecular overview.
abstract: Leaf epinasty involves the downward bending of leaves as a result of disturbances in their growth, with a greater expansion in adaxial cells as compared to abaxial surface cells. The co-ordinated anisotropy of growth in epidermal, palisade mesophyll and vascular tissues contributes to epinasty. This phenotype, which is regulated by auxin (indole-3-acetic acid, IAA), controls plant cell division and elongation by regulating the expression of a vast number of genes. Other plant hormones, such as ethylene, abscisic acid and brassinosteroids, also regulate epinasty and hyponasty. Reactive oxygen species (ROS) accumulation induced by auxins and 2,4-dichlorophenoxyacetic acid (2,4-D) triggers epinasty. The role of ROS and nitric oxide (NO) in the regulation of epinasty has recently been established. Thus, treatment with synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) induces disturbances in the actin cytoskeleton through ROS and NO-dependent post-translational modifications in actin by carbonylation and S-nitrosylation, which cause a reduction in the actin filament. Reorientation of microtubules has become a major feature of the response to auxin. The cytoskeleton is therefore a key player in epinastic development.
authors.affiliation: Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008, Granada, Spain. Electronic address: luisamaria.sandalio@eez.csic.es.
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Sandalio
authors.affiliation: Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008, Granada, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Rodríguez-Serrano
authors.affiliation: Department of Biochemistry and Molecular and Cellular Biology of Plants, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008, Granada, Spain.
authors.forename: María C
authors.initials: MC
authors.lastname: Romero-Puertas
mesh_terms: D003599:Cytoskeleton / Q000502:physiology; D007210:Indoleacetic Acids / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D018515:Plant Leaves / Q000254:growth & development*; D017382:Reactive Oxygen Species / Q000378:metabolism; D020239:Receptor Cross-Talk
chemical_list: D007210:Indoleacetic Acids; D017382:Reactive Oxygen Species; D009569:Nitric Oxide
keywords: 2,4-dichlorophenoxyacetic acid; Actin cytoskeleton; Auxin; Epinasty; Ethylene; Hyponasty; Microtubules; Nitric oxide; Reactive oxygen species