Guy, R. and Krakowski, J. 2003. Autumn Colours – Nature's Canvas is a Silk Parasol. Davidsonia. 14(4):111-120.
The variety and widespread nature of leaf colour change in autumn has led to investigation of the biochemical pathways and compounds responsible. The synthesis of bright red colouration initiated by longer nights prior to leaf abscission in deciduous species points to some adaptive value for this expensive ephemeral trait. It is hypothesized that during the breakdown of the unstable chlorophyll and the dismantling of the nutrient-rich photosynthetic apparatus, red anthocyanins provide a more biochemically parsimonious alternative to the elaborate xanthophyll system. This alternative enables leaves to screen out excess light energy and circumvent photooxidative damage to leaf cells, while allowing photosynthesis to persist at low rates in support of metabolic processes and phloem loading required for nutrient resorption from leaves.
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