Resorption Protection. Anthocyanins Facilitate Nutrient Recovery in Autumn by Shielding Leaves from Potentially Damaging Light Levels

Abstract

The resorption protection hypothesis, which states that anthocyanins protect foliar nutrient resorption during senescence by shielding photosynthetic tissues from excess light, was tested using wild-type (WT) and anthocyanin-deficient mutants of three deciduous woody species, Cornus sericea, Vaccinium elliottii (Chapmn.), and Viburnum sargentii (Koehne). WT Betula papyrifera (Marsh) was included to compare the senescence performance of a species that does not produce anthocyanins in autumn. Plants were subjected to three environmental regimes during senescence: an outdoor treatment; a 5-d high-stress (high light and low temperature) treatment followed by transfer to a low-stress environment and a low-stress treatment that served as control. In the outdoor treatment, the appearance of anthocyanins in senescing leaves of WT plants was concomitant with the development of photo-inhibition in mutant plants of all three anthocyanin-producing species. In the high-stress environment, WT plants maintained higher photochemical efficiencies than mutants and were able to recover when transferred to the low-stress environment, whereas mutant leaves dropped while still green and displayed signs of irreversible photooxidative damage. Nitrogen resorption efficiencies and proficiencies of all mutants in both stressful treatments were significantly lower than the WT counterparts. B. papyrifera displayed photochemical efficiencies and nitrogen resorption performance comparable with the highest of the anthocyanin-producing species in all three senescing environments, indicating a photoprotective strategy divergent from the other species studied. These results strongly support the resorption protection hypothesis of anthocyanins in senescing leaves.The role of anthocyanins in plant foliage has long been the subject of study and speculation (for review, see Chalker-Scott, 1999;Steyn et al., 2002). Foliar anthocyanins arise in a great diversity of plant species across a broad range of environments, often occurring in response to environmental stresses such as nutrient deficiency, drought, and low temperature (Steyn et al., 2002). In many species, anthocyanins are produced at specific physiological stages, appearing in expanding, mature, or senescing leaves exposed to high light. Observations over a century ago led to the light screen hypothesis, which states that foliar anthocyanins shade the photosynthetic apparatus from excess light (for review, see Wheldale, 1916).The resorption protection hypothesis (Hoch et al., 2001) proposed that the shading of photosynthetic tissues by anthocyanins produced during senescence helps protect the plant's ability to resorb foliar nutrients by shielding leaves from potentially harmful light levels. This hypothesis is based on the ideas that senescence-related processes lead to increased vulnerability to damage from visible light, resulting in reduced photosynthetic capacity (photo-inhibition) and that severe photo-inhibition during senescence can significantly affect a plant's ability to resorb foli...

Ecophysiological responses of two dominant subalpine tree species Betula albo-sinensis and Abies faxoniana to intra- and interspecific competition under elevated temperature

“…Our conclusion is reinforced by the fact that the leaves of A. faxoniana from interspecific competition displayed a higher maximal PSII quantum yield and higher effective quantum yield of PSII than did plants growing alone, resulting in a high foliar N resorption. Shading facilitates the recovery of foliar nutrients by shielding photosynthetic tissues from excess light under ET, because resorption is dependent on a competent photosynthetic system to supply the energy needed for the catabolic activity (Hoch et al, 2003). In contrast, in B. albo-sinensis, A 1400 , relative height growth rate and relative diameter growth rate were negatively affected by interspecific competition under ET.…”

A Cellular Timetable of Autumn Senescence

“…Carotenoids are not the only pigments responsible for autumn colors; anthocyanins often accumulate (Lee et al, 2003), giving rise to dark-reddish leaf colors, and have been proposed to function as light protectants during the nutrient recycling of senescing leaves (Feild et al, 2001;Hoch et al, 2003). Therefore, we quantified anthocyanin levels to see whether they changed during autumn senescence in aspen leaves.…”

Members of theLBDFamily of Transcription Factors Repress Anthocyanin Synthesis and Affect Additional Nitrogen Responses inArabidopsis

“…They give color to flowers and fruits (Winkel-Shirley, 2001) and are important antioxidants (Gould et al, 2002). Their antioxidant properties have nutritional value for humans and help to protect plants from oxidative damage (Nagata et al, 2003), allowing nutrient recovery in aging and senescing leaves (Hoch et al, 2003). Synthesis of flavonoids and especially anthocyanins, which are responsible for purple coloration of leaves, is stimulated by abiotic and biotic stresses (Dixon and Paiva, 1995), including cold, high irradiance, excess sugar (Tsukaya et al, 1991), or limitation of inorganic macronutrients like phosphorous (P) and N Morcuende et al, 2007).…”