title: Rapid modulation of ultraviolet shielding in plants is influenced by solar ultraviolet radiation and linked to alterations in flavonoids.
abstract: The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) and the resultant decrease in epidermal UV transmittance (TUV ) are primary protective mechanisms employed by plants against potentially damaging solar UV radiation and are critical components of the overall acclimation response of plants to changing solar UV environments. Whether plants can adjust this UV sunscreen protection in response to rapid changes in UV, as occurs on a diurnal basis, is largely unexplored. Here, we use a combination of approaches to demonstrate that plants can modulate their UV-screening properties within minutes to hours, and these changes are driven, in part, by UV radiation. For the cultivated species Abelmoschus esculentus, large (30-50%) and reversible changes in TUV occurred on a diurnal basis, and these adjustments were associated with changes in the concentrations of whole-leaf UV-absorbing compounds and several quercetin glycosides. Similar results were found for two other species (Vicia faba and Solanum lycopersicum), but no such changes were detected in Zea mays. These findings reveal a much more dynamic UV-protection mechanism than previously recognized, raise important questions concerning the costs and benefits of UV-protection strategies in plants and have practical implications for employing UV to enhance crop vigor and quality in controlled environments.
authors.affiliation: Department of Biological Sciences and Environment Program, Loyola University New Orleans, New Orleans, LA, 70118, USA.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Barnes
authors.affiliation: Department of Biological Sciences and Environment Program, Loyola University New Orleans, New Orleans, LA, 70118, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Tobler
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Ken
authors.initials: K
authors.lastname: Keefover-Ring
authors.affiliation: Department of Forest, Rangeland and Fire Sciences, University of Idaho, Moscow, ID, 83844, USA.
authors.forename: Stephan D
authors.initials: SD
authors.lastname: Flint
authors.affiliation: Department of Biological Sciences and Environment Program, Loyola University New Orleans, New Orleans, LA, 70118, USA.
authors.forename: Anne E
authors.initials: AE
authors.lastname: Barkley
authors.affiliation: Department of Wildland Resources, Utah State University, Logan, UT, 84322, USA.
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Ryel
authors.affiliation: Department of Entomology, University of Wisconsin-Madison, Madison, WI, 53706, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Lindroth
mesh_terms: D028483:Abelmoschus / Q000502:physiology / Q000528:radiation effects*; D000064:Acclimatization; D002940:Circadian Rhythm; D005419:Flavonoids / Q000502:physiology / Q000528:radiation effects*; D031584:Hibiscus / Q000502:physiology / Q000528:radiation effects*; D018551:Solanum lycopersicum / Q000502:physiology / Q000528:radiation effects*; D019441:Plant Epidermis / Q000502:physiology / Q000528:radiation effects; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D013472:Sunlight; D014466:Ultraviolet Rays; D031307:Vicia faba / Q000502:physiology / Q000528:radiation effects*; D003313:Zea mays / Q000502:physiology / Q000528:radiation effects*
chemical_list: D005419:Flavonoids
keywords: UV protection; UV-A; UV-B; UV-absorbing compounds; acclimation; chlorophyll fluorescence; diurnal change; epidermal UV transmittance; quercetin