Rapid modulation of ultraviolet shielding in plants is influenced by solar ultraviolet radiation and linked to alterations in flavonoids

• Published in: Plant, cell and environment Vol. 39; no. 1; pp. 222 - 230
• Main Authors: Barnes, Paul W, Tobler, Mark A, Keefover‐Ring, Ken, Flint, Stephan D, Barkley, Anne E, Ryel, Ronald J, Lindroth, Richard L
• Format: Journal Article
• Language: English
• Published: United States Blackwell Scientific Publications 01.01.2016; Wiley Subscription Services, Inc
• Subjects: Abelmoschus - physiology; Abelmoschus - radiation effects; Abelmoschus esculentus; acclimation; Acclimatization; chlorophyll fluorescence; Circadian Rhythm; diurnal change; epidermal UV transmittance; Flavonoids - physiology; Flavonoids - radiation effects; glycosides; Hibiscus - physiology; Hibiscus - radiation effects; Lycopersicon esculentum - physiology; Lycopersicon esculentum - radiation effects; phenylpropanoids; Plant Epidermis - physiology; Plant Epidermis - radiation effects; Plant Leaves - physiology; Plant Leaves - radiation effects; quercetin; Solanum lycopersicum; Sunlight; sunscreens; transmittance; ultraviolet radiation; Ultraviolet Rays; UV protection; UV‐A; UV‐absorbing compounds; UV‐B; Vicia faba; Vicia faba - physiology; Vicia faba - radiation effects; vigor; Zea mays; Zea mays - physiology; Zea mays - radiation effects; UV protection; UV-B; epidermal UV transmittance; UV-A; UV-absorbing compounds; acclimation; chlorophyll fluorescence; quercetin; diurnal change
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.12609

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.