Biodiv Sci ›› 2009, Vol. 17 ›› Issue (2): 188-194.  DOI: 10.3724/SP.J.1003.2009.09007

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Physiological functions of the red leaves of Wedelia trilobata induced by high irradiance in summer

Liying Song1, Lanlan Sun1, Zhan Shu2, Weihua Li1, Changlian Peng1,*()   

  1. 1 Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, College of Life Science, South China Normal University, Guangzhou 510631
    2 Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032
  • Received:2009-01-06 Accepted:2009-03-06 Online:2009-03-20 Published:2009-03-20
  • Contact: Changlian Peng

Abstract:

Wedelia trilobata, a creeping herb native to Central and South America, is one of the world’s 100 worst invasive alien species. It was introduced into South China and has become a noxious invasive weed in agricultural fields, plantations and natural forests. In natural communities, it is observed that the leaves of W. trilobata turn from green to red under high irradiance in summer. The aims of this study were to explore what causes the leaf color change in W. trilobata and what the physiological consequences are. Anthocyanin content was significantly higher in red than in green leaves of W. trilobata, suggesting that the accumulation of anthocyanin at high irradiance was related to the leaf color change. The increased content of anthocyanin contributed to a higher total antioxidant capability in red W. trilobata leaves . Consistent with the higher antioxidant capability, decreases in maximum quantum efficiency of photosystem II photochemistry and the effective PSII quantum yield caused by artificial photo-oxidative stress were respectively smaller in red (28.2% and 79.1%) than in green leaves of W. trilobata (70.9% and 93.8%). Leaf color change was not observed in native W. chinensis. Our results suggest that the color change may be a physiological mechanism employed by the invasive W. trilobata to acclimate to high irradiance in summer.

Key words: Wedelia trilobata, anthocyanin, methyl viologen, photooxidation, chlorophyll fluorescence, adaptive mechanism