The impact of light intensity on shade‐induced leaf senescence

Abstract

Plants often have to cope with altered light conditions, which in leaves induce various physiological responses ranging from photosynthetic acclimation to leaf senescence. However, our knowledge of the regulatory pathways by which shade and darkness induce leaf senescence remains incomplete. To determine to what extent reduced light intensities regulate the induction of leaf senescence, we performed a functional comparison between Arabidopsis leaves subjected to a range of shading treatments. Individually covered leaves, which remained attached to the plant, were compared with respect to chlorophyll, protein, histology, expression of senescence-associated genes, capacity for photosynthesis and respiration, and light compensation point (LCP). Mild shading induced photosynthetic acclimation and resource partitioning, which, together with a decreased respiration, lowered the LCP. Leaf senescence was induced only under strong shade, coinciding with a negative carbon balance and independent of the red/farred ratio. Interestingly, while senescence was significantly delayed at very low light compared with darkness, phytochrome A mutant plants showed enhanced chlorophyll degradation under all shading treatments except complete darkness. Taken together, our results suggest that the induction of leaf senescence during shading depends on the efficiency of carbon fixation, which in turn appears to be modulated via light receptors such as phytochrome A.

Grain Yield Differences of Soybean Cultivars Due to Solar Radiation Interception

“…Thereby, there might be an energy imbalance in plants since the shaded structures spend energy in respiration, without producing through photosynthesis. Leaf senescence in the canopy lower part is accelerated due to a decrease in the proportion of red and far red light, signaling that light conditions would not satisfy the primary metabolism demands [14].…”

Comparative Performance of Three Tropical Turfgrasses Digitaria longiflora, Axonopus compressus and St. Augustinegrass under Simulated Shade Conditions

“…However, under 90% shade level, the low light condition has triggered leaf senescence in D. longiflora (as seen in the reduction of chlorophyll). Shade-induced leaf senescence has been suggested to be triggered by a negative carbon balance (respiration rate higher than photosynthetic rate) when the light intensity was lower than the photosynthetic light compensation point (Veierskov, 1987;Brouwer et al, 2012). On the other hand, no shade-induced senescence events were observed in St. Augustinegrass or A. compressus at 90% shade level.…”

“…In addition, leaf senescence was induced under severe shade conditions when plants were experiencing a net negative carbon balance i.e. increased respiration over photosynthesis (Brouwer et al, 2012).…”

Comparative Extraction of Chlorophylls in Selected Forest and Savanna Mosses Using Dimethylsulphoxide and Acetone

“…Chlorophyll, a natural pigment produced by green plants and algae, absorbs light energy from the sun, which is then used to synthesize carbohydrates from carbondioxide in a process called photosynthesis (Raven et al, 2005). Chlorophyll content can change in response to biotic and abiotic stresses such as pathogen infection (Mur et al, 2010) and light stress (Kitajima and Hogan, 2003;Brouwer et al, 2012).…”