Physiological significance of anthocyanins during autumnal leaf senescence

Abstract

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.

Generation of Hydrogen Peroxide in Chloroplasts of Arabidopsis Overexpressing Glycolate Oxidase as an Inducible System to Study Oxidative Stress

“…On the other hand, GO plants showed a reduced expression of genes involved in anthocyanin biosynthesis, such as PAL1, CHS, and DFR. This could be related to a suppression of the senescence program in which anthocyanin levels are elevated (Hoch et al, 2001). Both effects could be part of a mechanism that drives the acclimatory resistance in plants exposed to sublethal doses of H 2 O 2 that did not affect the viability of Arabidopsis plants but may play a regulatory role in the cellular network, leading to altered gene expression and the reconfiguration of metabolism in order to adapt to oxidative conditions.…”

Decoupling vigour and quality in the autumn colours game: Weak individuals can signal, cheating can pay

“…Red may protect the leaf from the damaging effects of light at low temperatures (photo-inhibition and photo-oxidation), allowing a more efficient resorption of nutrients, especially nitrogen (the photoprotection theory: Pringsheim, 1879-1882; Gould et al, 1995;Hoch et al, 2001;Feild et al, 2001;Lee et al, 2003).…”

Gene Expression in Autumn Leaves

“…The most obvious visual phenotype of senescence, the color changes from green to yellow, red, or orange, is the result of chlorophyll degradation, often combined with anthocyanin accumulation (Hoch et al, 2001). During senescence, photosynthesis declines and the leaf changes its metabolism from anabolism to catabolism and the chloroplasts turn into gerontoplasts.…”