Hughes, Nicole M. , Smith, William K. .
Winter color change: The adaptive role of anthocyanin pigments in leaves of broadleaf evergreen species.
Leaves of many evergreen species turn red when exposed to high sunlight during winter due to production of photoprotective anthocyanin pigments, while leaves of other species, lacking anthocyanin, remain green. Why some species synthesize anthocyanin pigments while others do not is currently unknown. Furthermore, the relative photosynthetic performance of anthocyanic (red) and acyanic (green) evergreens has yet to be described. Here we present seasonal ecophysiological data for five red and green broadleaf evergreen species. We hypothesize that species which synthesize anthocyanins in winter leaves correspond to those with the most drastic seasonal photosynthetic declines, as reduced energy sinks increase vulnerability to photoinhibition and need for photoprotection. Our results did not support this hypothesis, as gas exchange measurements showed no difference in mean seasonal photosynthetic capacity between red and green-leaf species. Consistent with anthocyanin’s shading effect, red-leaf species had significantly higher chlorophyll content, lower chlorophyll a/b ratios, and higher maximum light capture efficiency of PSII (Fv/Fm) than green-leaf species during the winter, but not during the summer (when all leaves were green). We conclude that anthocyanin production during winter is likely not associated with diminished photosynthetic capacity, and may simply represent an alternative photoprotective strategy utilized by some species during winter.
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1 - Wake Forest University, Biology, Winston Hall 136, Winston-Salem, NC, 27109, USA
2 - Wake Forest University, Department of Biology, PO Box 7325, 226 Winston Hall, Winston-Salem, North Carolina, 27109-7325, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, July 29th, 2008
Time: 8:00 AM