Does the photosynthetic light‐acclimation need change in leaf anatomy?

Abstract

There is a strong correlation between leaf thickness and the light-saturated rate of photosynthesis per unit leaf area ( P max ). However, when leaves are exposed to higher light intensities after maturation, P max often increases without increasing leaf thickness. To elucidate the mechanism with which mature leaves increase P max , the change in anatomical and physiological characteristics of mature leaves of Chenopodium album, which was transferred from low to high light condition, were examined. When compared with leaves subjected to low light continuously (LL leaves), the leaves transferred from low to high light (LH leaves) significantly increased P max . The transfer also increased the area of chloroplasts facing the intercellular space ( S c ) and maintained a strong correlation between P max and S c . The mesophyll cells of LL leaves had open spaces along cell walls where chloroplasts were absent, which enabled the leaves to increase P max when they were exposed to high light (LH). However, the LH leaves were not thick enough to allow further increase in P max to the level in HH leaves. Thus leaf thickness determines an upper limit of P max of leaves subjected to a change from low to high light conditions. Shade leaves would only increase P max when they have open space to accommodate chloroplasts which elongate after light conditions improve.

Evidence of higher photosynthetic plasticity in the early successional Guazuma ulmifolia Lam. compared to the late successional Hymenaea courbaril L. grown in contrasting light environments

“…Changes in parameters such as the chlorophyll a/b ratio, the PSII/PSI ratio, or A max per unit of chlorophyll are indicative of chloroplast level acclimation. Leaf level acclimation refers to the markedly different anatomies of high and low light leaves: the 'sun-type' morphology would generally consist of thicker leaves with more columnar mesophyll cells (Sims and Pearcy, 1992;Oguchi et al, 2003). Leaf level acclimation seems to be largely controlled by signals perceived, generated in mature leaves and transduced to newly developing leaves, whereas chloroplast level acclimation is regulated by environmental events (Yano and Terashima, 2001;Oguchi et al, 2003).…”

“…Leaf level acclimation refers to the markedly different anatomies of high and low light leaves: the 'sun-type' morphology would generally consist of thicker leaves with more columnar mesophyll cells (Sims and Pearcy, 1992;Oguchi et al, 2003). Leaf level acclimation seems to be largely controlled by signals perceived, generated in mature leaves and transduced to newly developing leaves, whereas chloroplast level acclimation is regulated by environmental events (Yano and Terashima, 2001;Oguchi et al, 2003). In leaves transferred from low to high light, successful light acclimation appears to be related to coordinated increases in both carboxylation and electron transport activity (Boardman, 1977;Langenheim et al, 1984;Thompson et al, 1992 for each species and light environment, under controlled temperature (about 27 °C) and CO 2 concentration (400 ± 1.2 μmol.mol -1 ).…”

Effects of low temperature acclimation on photosynthesis in three Chilean Proteaceae

“…It is notorious that G. avellana, in non-acclimated state, presents an intermediate behavior in the measured pigments parameters, while under cold-acclimation conditions it was more affected. A higher acclimation capacity would be advantageous when radiation or temperature suddenly increase having important effects on forest composition and regeneration (Oguchi et al 2003). NPQ in cold-acclimated E. coccineum and L. ferruginea showed a strong increase from 0 to 200 μmol photons m -2 s -1 .…”

Photosynthetic acclimation within individual Typha latifolia leaf segments

“…These changes may include adjustments in partitioning among carboxylation, electron transport and light harvesting, chloroplast ultrastructure, volume, and orientation (Sebaa et al, 1987;De la Torre and Burkey, 1990a;Sailaja and Rama Das, 1995;Frank et al, 2001;Oguchi et al, 2003Oguchi et al, , 2005. The high N content of shaded segments should not be viewed as wasteful.…”

“…The local light environment influences the morphological development of leaves in many species, resulting in comparatively thick leaves in bright locations Hikosaka, 1996;Niinemets, 2007). Fully expanded leaves have a limited capacity for morphological change (Sims and Pearcy, 1992;Evans and Porter, 2001;, and acclimation by these leaves requires biochemical changes in carboxylation, electron transport, and light harvesting, as well as modifications to chloroplast structure and orientation (Sebaa et al, 1987;De la Torre and Burkey, 1990a, b;Avalos and Mulkey, 1999;Frank et al, 2001;Murchie et al, 2002;Oguchi et al, 2003Oguchi et al, , 2005Walters, 2005).…”