© 2001 Heron Publishing—Victoria, Canada
Physiological significance of anthocyanins during autumnal leaf senescence
William A. Hoch (1), Eric L. Zeldin (1) and Brent H. McCown (1)
1. Department of Horticulture, University of Wisconsin-Madison, Madison, WI 53706, USA / Received August 10, 1999
Summary
The light screen hypothesis states that foliar anthocyanins shade the photosynthetic apparatus from excess light. In this
paper we extend the light screen hypothesis, postulating that plant species at risk of photoinhibitory conditions during autumnal
leaf senescence often utilize anthocyanins to protect the photosynthetic apparatus during the period of nutrient resorption.
When senescence-related photosynthetic instabilities are compounded by other environmental stresses, particularly low temperature,
severe photoinhibition may result in reduced resorption of critical foliar nutrients, which can significantly affect plant
fitness. There is evidence that environments where low and often freezing temperatures are common in autumn selectively favor
the production of anthocyanins in senescing foliage. The stimuli for, and the timing and location of, autumnal anthocyanin
production are all consistent with a photoprotective role for these pigments in senescing leaves. Furthermore, differences
in nitrogen allocation strategies between early and late successional species appear to affect photosynthetic stability during
leaf senescence, resulting in a reduced need for foliar autumnal anthocyanins in many early successional plants. The ecological
and physiological evidence presented in this paper suggest that, for many deciduous species, the production of anthocyanins
provides effective photoprotection during the critical period of foliar nutrient resorption.
Keywords:
light screen, photoinhibition, photoprotection, resorption, successional ecology.
