Contrasting strategies for UV-B screening in sub-Arctic dwarf shrubs

• Published in: Plant, Cell & Environment
• Main Authors: Semerdjieva, S. I., Sheffield, E., Phoenix, G. K., Gwynn-Jones, D., Callaghan, T. V., Johnson, Giles N.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2003
• Subjects: Enhanced UV-B; Fluorescence microscopy; Phenolics; Vaccinium myrtillus; Vaccinium uliginosum; Vaccinium vitis-idaea; Arctic; North Sweden
• Online Access: https://research.manchester.ac.uk/en/publications/190385e5-9c59-4953-9761-d169f6fbd669; https://doi.org/10.1046/j.1365-3040.2003.01029.x

The content and distribution of UV-absorbing phenolic compounds was investigated in leaves of three species of Vaccinium co-existing at a site in north Sweden. Vaccinium myrtillus L., Vaccinium vitis-idaea L., and Vaccinium uliginosum L. exhibit markedly different strategies, in terms of localization and content of leaf phenolics and in their responses to UV-B enhancement. Plants were exposed to either ambient radiation or to enhancement of UV-B corresponding to 15% (clear sky) depletion of stratospheric ozone for approximately 10 years prior to commencement of this study. Vaccinium myrtillus contained the highest concentration of methanol-extractable UV-B-absorbing compounds, which was elevated in plants exposed to enhanced UV-B. Fluorescence and confocal laser scanning microscopy showed that these compounds were distributed throughout the leaf, and were particularly concentrated in chlorophyll-containing cells. In V. vitisidaea, most phenolic compounds were cell wall-bound and concentrated in the walls of the epidermis; this pool increased in response to UV-B enhancement. It is suggested that these two plants represent extreme forms of two divergent strategies for UV-B screening, the different responses possibly being related to leaf longevity in the two species. The response of V. uliginosum was intermediate between the other two, with high concentrations of cell wall-bound phenolics in the epidermis but with this pool decreasing, and the methanol-soluble pool tending to increase, after exposure to enhanced UV-B. One explanation for this response is that this plant is deciduous, like V. myrtillus, but has leaves that are structurally similar to those of V. vitis-idaea.