Acclimation to UV‐B radiation and visible light in Lactuca sativa involves up‐regulation of photosynthetic performance and orchestration of metabolome‐wide responses

• Published in: Plant, cell and environment Vol. 38; no. 5; pp. 929 - 940
• Main Authors: WARGENT, J. J, NELSON, B. C. W, MCGHIE, T. K, BARNES, P. W
• Format: Journal Article
• Language: English
• Published: United States Blackwell Scientific Publications 01-05-2015; Wiley Subscription Services, Inc
• Subjects: acclimation; Acclimatization; chlorophyll; crops; fluorescence; Gas exchange; Lactuca - metabolism; Lactuca - radiation effects; Lactuca sativa; Liquid chromatography; Mass spectrometry; Metabolome; metabolomics; photomorphogenesis; photoprotection; photosynthesis; Photosynthesis - radiation effects; plant development; Plant Leaves - metabolism; Plant Leaves - radiation effects; Seedlings; solar radiation; Ultraviolet radiation; Ultraviolet Rays; photoprotection; photosynthesis
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.12392

UV‐B radiation is often viewed as a source of stress for higher plants. In particular, photosynthetic function has been described as a common target for UV‐B impairment; yet as our understanding of UV‐B photomorphogenesis increases, there are opportunities to expand the emerging paradigm of regulatory UV response. Lactuca sativa is an important dietary crop species and is often subjected to rapid sunlight exposure at field transfer. Acclimation to UV‐B and visible light conditions in L. sativa was dissected using gas exchange and chlorophyll fluorescence measurements, in addition to non‐destructive assessments of UV epidermal shielding (SUV). After UV‐B treatment, seedlings were subjected to wide‐range metabolomic analysis using liquid chromatography hybrid quadrupole time‐of‐flight high‐resolution mass spectrometry (LC‐QTOF‐HRMS). During the acclimation period, net photosynthetic rate increased in UV‐treated plants, epidermal UV shielding increased in both subsets of plants transferred to the acclimatory conditions (UV+/UV− plants) and Fᵥ/Fₘdeclined slightly in UV+/UV− plants. Metabolomic analysis revealed that a key group of secondary compounds was up‐regulated by higher light conditions, yet several of these compounds were elevated further by UV‐B radiation. In conclusion, acclimation to UV‐B radiation involves co‐protection from the effects of visible light, and responses to UV‐B radiation at a photosynthetic level may not be consistently viewed as damaging to plant development.